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0801.0323
|
The influence of a possible non zero chemical potential $\mu$ on the nature
of dark energy is investigated by assuming that the dark energy is a
relativistic perfect simple fluid obeying the equation of state (EoS),
$p=\omega \rho$ ($\omega <0, constant$). The entropy condition, $S \geq 0$,
implies that the possible values of $\omega$ are heavily dependent on the
magnitude, as well as on the sign of the chemical potential. For $\mu >0$, the
$\omega$-parameter must be greater than -1 (vacuum is forbidden) while for $\mu
< 0$ not only the vacuum but even a phantomlike behavior ($\omega <-1$) is
allowed. In any case, the ratio between the chemical potential and temperature
remains constant, that is, $\mu/T=\mu_0/T_0$. Assuming that the dark energy
constituents have either a bosonic or fermionic nature, the general form of the
spectrum is also proposed. For bosons $\mu$ is always negative and the extended
Wien's law allows only a dark component with $\omega < -1/2$ which includes
vacuum and the phantomlike cases. The same happens in the fermionic branch for
$\mu <0$. However, fermionic particles with $\mu >0$ are permmited only if $-1
< \omega < -1/2$. The thermodynamics and statistical arguments constrain the
EoS parameter to be $\omega < -1/2$, a result surprisingly close to the maximal
value required to accelerate a FRW type universe dominated by matter and dark
energy ($\omega \lesssim -10/21$).
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
1111.1656
|
We investigate the QCD phase diagram as a function of isospin chemical
potential at a fixed temperature by directly putting large numbers of \pi^+s
into the system. Correlation functions of N \pi^+s systems involves N!N!
contractions, and become extremely expensive when N is large. In order to
alleviate this problem, a recursion relation of correlation functions has been
derived in Ref. [1] that substantially reduces the number of independent
contractions needed and makes the study of many pions systems be possible. In
this proceeding this method is investigated numerically. We have also
constructed a new method that is even more efficient, enabling us to study
systems of up to 72 \pi^+s.
|
[
"hep-lat"
] |
hep-lat
|
High Energy Physics - Lattice
| 3,092High Energy Physics - Lattice
|
|
gr-qc/0010055
|
Classical black holes are defined by the property that things can go in, but
don't come out. However, Stephen Hawking calculated that black holes actually
radiate quantum mechanical particles. The two important ingredients that result
in back hole evaporation are (1) the spacetime geometry, in particular the
black hole horizon, and (2) the fact that the notion of a "particle" is not an
invariant concept in quantum field theory. These notes contain a step-by-step
presentation of Hawking's calculation. We review portions of quantum field
theory in curved spacetime and basic results about static black hole
geometries, so that the discussion is self-contained. Calculations are
presented for quantum particle production for an accelerated observer in flat
spacetime, a black hole which forms from gravitational collapse, an eternal
Schwarzschild black hole, and charged black holes in asymptotically deSitter
spacetimes. The presentation highlights the similarities in all these
calculations. Hawking radiation from black holes also points to a profound
connection between black hole dynamics and classical thermodynamics. A theory
of quantum gravity must predicting and explain black hole thermodynamics. We
briefly discuss these issues and point out a connection between black hole
evaportaion and the positive mass theorems in general relativity.
|
[
"gr-qc"
] |
gr-qc
|
General Relativity and Quantum Cosmology
| 2,674General Relativity and Quantum Cosmology
|
|
2209.04934
|
Partial differential equations (PDEs) see widespread use in sciences and
engineering to describe simulation of physical processes as scalar and vector
fields interacting and coevolving over time. Due to the computationally
expensive nature of their standard solution methods, neural PDE surrogates have
become an active research topic to accelerate these simulations. However,
current methods do not explicitly take into account the relationship between
different fields and their internal components, which are often correlated.
Viewing the time evolution of such correlated fields through the lens of
multivector fields allows us to overcome these limitations. Multivector fields
consist of scalar, vector, as well as higher-order components, such as
bivectors and trivectors. Their algebraic properties, such as multiplication,
addition and other arithmetic operations can be described by Clifford algebras.
To our knowledge, this paper presents the first usage of such multivector
representations together with Clifford convolutions and Clifford Fourier
transforms in the context of deep learning. The resulting Clifford neural
layers are universally applicable and will find direct use in the areas of
fluid dynamics, weather forecasting, and the modeling of physical systems in
general. We empirically evaluate the benefit of Clifford neural layers by
replacing convolution and Fourier operations in common neural PDE surrogates by
their Clifford counterparts on 2D Navier-Stokes and weather modeling tasks, as
well as 3D Maxwell equations. For similar parameter count, Clifford neural
layers consistently improve generalization capabilities of the tested neural
PDE surrogates. Source code for our PyTorch implementation is available at
https://microsoft.github.io/cliffordlayers/.
|
[
"cs.LG",
"cs.CV",
"physics.flu-dyn"
] |
cs.LG
|
cs.CV
|
Machine Learning;Computer Vision and Pattern Recognition;Fluid Dynamics
| 7,267longtail
|
1705.06625
|
We introduce a weighed-loop algorithm that is applicable to any weighed graph
network. It is designed to prefer a route of energetically unfavourable bonds
in the lattice that can then be flipped without changing the structure inside
and outside the enclosed loop. Due to this property there are effectively no
energy barriers thus making this algorithm very suitable for finding low energy
states in very rough energy landscapes. We apply this algorithm to the random
bond Ising model with domain walls and show that the weighed-loop algorithm can
outperform Niedermayer's algorithm for low enough temperatures and high enough
disorder. We consolidate the high-temperature behaviour of the roughness of a
domain-wall with a low-temperature expansion presented in this paper and show
agreement with results from our simulations. The effects of temperature,
disorder, and system size on the roughness of domain-walls is also
investigated.
|
[
"cond-mat.stat-mech"
] |
cond-mat.stat-mech
|
Statistical Mechanics
| 6,821Statistical Mechanics
|
|
2006.06054
|
Sample-based planning is a powerful family of algorithms for generating
intelligent behavior from a model of the environment. Generating good candidate
actions is critical to the success of sample-based planners, particularly in
continuous or large action spaces. Typically, candidate action generation
exhausts the action space, uses domain knowledge, or more recently, involves
learning a stochastic policy to provide such search guidance. In this paper we
explore explicitly learning a candidate action generator by optimizing a novel
objective, marginal utility. The marginal utility of an action generator
measures the increase in value of an action over previously generated actions.
We validate our approach in both curling, a challenging stochastic domain with
continuous state and action spaces, and a location game with a discrete but
large action space. We show that a generator trained with the marginal utility
objective outperforms hand-coded schemes built on substantial domain knowledge,
trained stochastic policies, and other natural objectives for generating
actions for sampled-based planners.
|
[
"cs.AI"
] |
cs.AI
|
Artificial Intelligence
| 361Artificial Intelligence
|
|
2110.08501
|
Implicit knowledge, such as common sense, is key to fluid human
conversations. Current neural response generation (RG) models are trained to
generate responses directly, omitting unstated implicit knowledge. In this
paper, we present Think-Before-Speaking (TBS), a generative approach to first
externalize implicit commonsense knowledge (think) and use this knowledge to
generate responses (speak). We expect that externalizing implicit knowledge
allows more efficient learning, produces more informative responses, and
enables more explainable models. We analyze different choices to collect
knowledge-aligned dialogues, represent implicit knowledge, and transition
between knowledge and dialogues. Empirical results show TBS models outperform
end-to-end and knowledge-augmented RG baselines on most automatic metrics and
generate more informative, specific, and commonsense-following responses, as
evaluated by human annotators. TBS also generates knowledge that makes sense
and is relevant to the dialogue around 85\% of the time.
|
[
"cs.CL"
] |
cs.CL
|
Computation and Language
| 1,168Computation and Language
|
|
1007.5456
|
The one-shot classical capacity of a quantum channel quantifies the amount of
classical information that can be transmitted through a single use of the
channel such that the error probability is below a certain threshold. In this
work, we show that this capacity is well approximated by a
relative-entropy-type measure defined via hypothesis testing. Combined with a
quantum version of Stein's lemma, our results give a conceptually simple proof
of the well-known Holevo-Schumacher-Westmoreland theorem for the capacity of
memoryless channels. More generally, we obtain tight capacity formulas for
arbitrary (not necessarily memoryless) channels.
|
[
"quant-ph"
] |
quant-ph
|
Quantum Physics
| 5,985Quantum Physics
|
|
cond-mat/0407162
|
The anisotropy of wood within the radial-tangential (RT) growth plane has a
major influence on the cracking behavior perpendicular to grain. Within the
scope of this work, a two-dimensional discrete element model is developed,
consisting of beam elements for the representation of the micro structure of
wood. Molecular dynamics simulation is used to follow the time evolution of the
model system during the damage evolution in the RT plane under various loading
conditions. It is shown that the results are in good agreement with experiments
on spruce wood, and that the presented discrete element approach is applicable
for detailed studies of the dependence of the micro structure on mesoscopic
damage mechanism and dynamics of crack propagation in micro structured and
cellular materials like wood.
|
[
"cond-mat.mtrl-sci"
] |
cond-mat.mtrl-sci
|
Materials Science
| 4,287Materials Science
|
|
1211.0896
|
Monte Carlo (MC) simulations have been carried out to study the adsorption on
square and triangular lattices of particles with two bonding sites that, by
decreasing temperature or increasing density, polymerize reversibly into chains
with a discrete number of allowed directions and, at the same time, undergo a
continuous isotropic-nematic (IN) transition. The process has been monitored by
following the behavior of the adsorption isotherms for different values of
lateral interaction energy/temperature. The numerical data were compared with
mean-field analytical predictions and exact functions for noninteracting and 1D
systems. The obtained results revealed the existence of three adsorption
regimes in temperature. (1) At high temperatures, above the critical one
characterizing the IN transition at full coverage Tc(\theta=1), the particles
are distributed at random on the surface and the adlayer behaves as a
noninteracting 2D system. (2) At very low temperatures, the asymmetric monomers
adsorb forming chains over almost the entire range of coverage, and the
adsorption process behaves as a 1D problem. (3) In the intermediate regime, the
system exhibits a mixed regime and the filling of the lattice proceeds
according to two different processes. In the first stage, the monomers adsorb
isotropically on the lattice until the IN transition occurs in the system and,
from this point, particles adsorb forming chains so that the adlayer behaves as
a 1D fluid. The two adsorption processes are present in the adsorption
isotherms, and a marked singularity can be observed that separates both
regimes. Thus, the adsorption isotherms appear as sensitive quantities with
respect to the IN phase transition, allowing us (i) to reproduce the phase
diagram of the system for square lattices and (ii) to obtain an accurate
determination of the phase diagram for triangular lattices.
|
[
"cond-mat.stat-mech",
"physics.chem-ph",
"physics.comp-ph"
] |
cond-mat.stat-mech
|
physics.chem-ph
|
Statistical Mechanics;Chemical Physics;Computational Physics
| 6,850Statistical Mechanics;Chemical Physics;Computational Physics
|
1904.12192
|
Metal absorption line systems in distant quasar spectra probe of the history
of gas content in the universe. The MgII $\lambda \lambda$ 2796, 2803 doublet
is one of the most important absorption lines since it is a proxy of the star
formation rate and a tracer of the cold gas associated with high redshift
galaxies. Machine learning algorithms have been used to detect absorption lines
systems in large sky surveys, such as Principle Component Analysis (PCA),
Gaussian Process (GP) and decision trees. A very powerful algorithm in the
field of machine learning called deep neural networks, or '' deep learning'' is
a new structure of neural network that automatically extracts semantic features
from raw data and represents them at a high level. In this paper, we apply a
deep convolutional neural network for absorption line detection. We use the
previously published DR7 MgII catalog (Zhu et al. 2013) as the training and
validation sample and the DR12 MgII catalog as the test set. Our deep learning
algorithm is capable of detecting MgII absorption lines with an accuracy of
$\sim$94% . It takes only $\sim 9$ seconds to analyze $\sim$ 50000 quasar
spectra with our deep neural network, which is ten thousand times faster than
traditional methods, while preserving high accuracy with little human
interference. Our study shows that Mg II absorption line detection accuracy of
a deep neutral network model strongly depends on the filter size in the filter
layer of the neural network, and the best results are obtained when the filter
size closely matches the absorption feature size.
|
[
"astro-ph.GA",
"astro-ph.IM"
] |
astro-ph.GA
|
astro-ph.IM
|
Astrophysics of Galaxies;Instrumentation and Methods for Astrophysics
| 495Astrophysics of Galaxies;Instrumentation and Methods for Astrophysics
|
1302.2458
|
How do magnetohydrodynamic waves travel from the fully ionized corona, into
and through the underlying partially ionized chromosphere, and what are the
consequences for solar flares? To address these questions, we have developed a
2-fluid model (of plasma and neutrals) and used it to perform 1D simulations of
Alfv\'en waves in a solar atmosphere with realistic density and temperature
structure. Studies of a range of solar features (faculae, plage, penumbra and
umbra) show that energy transmission from corona to chromosphere can exceed 20%
of incident energy for wave periods of one second or less. Damping of waves in
the chromosphere depends strongly on wave frequency: waves with periods 10
seconds or longer pass through the chromosphere with relatively little damping,
however, for periods of 1 second or less, a substantial fraction (37%-100%) of
wave energy entering the chromosphere is damped by ion-neutral friction in the
mid and upper chromosphere, with electron resistivity playing some role in the
lower chromosphere and in umbras. We therefore conclude that Alfv\'enic waves
with periods of a few seconds or less are capable of heating the chromosphere
during solar flares, and speculate that they could also contribute to electron
acceleration or exciting sunquakes.
|
[
"astro-ph.SR"
] |
astro-ph.SR
|
Solar and Stellar Astrophysics
| 6,668Solar and Stellar Astrophysics
|
|
1210.5447
|
We study the multiwavelength properties of an optically selected sample of
Low Ionization Nuclear Emission-line Regions (LINERs), in an attempt to
determine the accretion mechanism powering their central engine. We show how
their X-ray spectral characteristics, and their spectral energy distribution
compare to luminous AGN, and briefly discuss their connection to their less
massive counter-parts galactic black-hole X-ray binaries.
|
[
"astro-ph.HE",
"astro-ph.GA"
] |
astro-ph.HE
|
astro-ph.GA
|
High Energy Astrophysical Phenomena;Astrophysics of Galaxies
| 2,991High Energy Astrophysical Phenomena;Astrophysics of Galaxies
|
2002.02127
|
There have been recent works on enabling in-band full-duplex operation using
millimeter-wave (mmWave) transceivers. These works are based solely on creating
sufficient isolation between a transceiver's transmitter and receiver via
multiple-input multiple-output (MIMO) precoding and combining. In this work, we
propose supplementing these beamforming strategies with analog
self-interference cancellation (A-SIC). By leveraging A-SIC, a portion of the
self-interference is cancelled without the need for beamforming, allowing for
more optimal beamforming strategies to be used in serving users. We use
simulation to demonstrate that even with finite resolution A-SIC solutions,
there are significant gains to be had in sum spectral efficiency. With a single
bit of A-SIC resolution, improvements over a beamforming-only design are
present. With 8 bits of A-SIC resolution, our design nearly approaches that of
ideal full-duplex operation. To the best of our knowledge, this is the first
mmWave full-duplex design that combines both beamforming and A-SIC to achieve
simultaneous transmission and reception in-band.
|
[
"eess.SP"
] |
eess.SP
|
Signal Processing
| 6,402Signal Processing
|
|
1901.04232
|
Self-organization is an ubiquitous phenomenon in nature which can be observed
in a variety of different contexts and scales, with examples ranging from fish
schools, swarms of birds or locusts, to flocks of bacteria. The observation of
such global patterns can often be reproduced in models based on simple
interactions between neighboring particles. In this paper we focus on two
particular interaction dynamics closely related to the one described in the
seminal paper of Vicsek and collaborators. After reviewing the current state of
the art in the subject, we study a numerical scheme for the kinetic equation
associated with the Vicsek models which has the specificity of reproducing many
physical properties of the continuous models, like the preservation of energy
and positivity and the diminution of an entropy functional. We describe a
stable pattern of bands emerging in the dynamics proposed by
Degond-Frouvelle-Liu dynamics and give some insights about their formation.
|
[
"math.NA",
"physics.comp-ph"
] |
math.NA
|
physics.comp-ph
|
Numerical Analysis;Computational Physics
| 5,026Numerical Analysis;Computational Physics
|
1811.09498
|
Carbon, a basic versatile element in our universe, exhibits rich varieties of
allotropic phases, most of which possess promising nontrivial topological
fermions. In this work, we identify a distinct topological phonon phase in a
realistic carbon allotrope with a body-centered cubic structure, termed
bcc-C$_{8}$. We show by symmetry arguments and effective model analysis that
there are three intersecting phonon nodal rings perpendicular to each other in
different planes. The intersecting phonon nodal rings are protected by
time-reversal and inversion symmetries, which quantize the corresponding Berry
phase into integer multiples of $\pi$. Unlike the electron systems, the phonon
nodal rings in bcc-C$_{8}$ are guaranteed to remain gapless due to the lack of
spin-orbital coupling. The nearly flat drumhead surface states projected on
semi-infinite (001) and (110) surfaces of bcc-C$_{8}$ are clearly visible. Our
findings not only discover promising nodal ring phonons in a carbon allotrope,
but also provide emergent avenues for exploring topological phonons beyond
fermionic electrons in carbon-allotropic structures with attractive features.
|
[
"cond-mat.mtrl-sci",
"cond-mat.mes-hall"
] |
cond-mat.mtrl-sci
|
cond-mat.mes-hall
|
Materials Science;Mesoscale and Nanoscale Physics
| 4,330Materials Science;Mesoscale and Nanoscale Physics
|
1905.05745
|
This paper gives a universal definition of $\mathbb{F}_q [t]$ in
$\mathbb{F}_q (t)$ using 89 quantifiers, more direct than those that exist in
the current literature. The language $\mathcal{L}_{\mbox{rings}, t}$ we
consider here is the language of rings $\{0, 1, +, -, \cdot\}$ with an
additional constant symbol $t$. We then modify this definition marginally to
universally define $\mathbb{F}_q [t]$ in $\mathbb{F}_q (t)$ without parameters,
using 90 quantifiers. We assume throughout that the characteristic of
$\mathbb{F}_q$ is odd.
|
[
"math.LO"
] |
math.LO
|
Logic
| 3,800Logic
|
|
gr-qc/0609110
|
A number of different methods have been proposed to identify unanticipated
burst sources of gravitational waves in data arising from LIGO and other
gravitational wave detectors. When confronted with such a wide variety of
methods one is moved to ask if they are all necessary, i.e. given detector data
that is assumed to have no gravitational wave signals present, do they
generally identify the same events with the same efficiency, or do they each
'see' different things in the detector? Here we consider three different
methods, which have been used within the LIGO Scientific Collaboration as part
of its search for unanticipated gravitational wave bursts. We find that each of
these three different methods developed for identifying candidate gravitational
wave burst sources are, in fact, attuned to significantly different features in
detector data, suggesting that they may provide largely independent lists of
candidate gravitational wave burst events.
|
[
"gr-qc"
] |
gr-qc
|
General Relativity and Quantum Cosmology
| 2,674General Relativity and Quantum Cosmology
|
|
2104.14318
|
The decoupling of heavy fields as required by the Appelquist-Carazzone
theorem plays a fundamental role in the construction of any effective field
theory. However, it is not a trivial task to implement a renormalization
prescription that produces the expected decoupling of massive fields, and it is
even more difficult in curved spacetime. Focused on this idea, we consider the
renormalization of the one-loop effective action for the Yukawa interaction
with a background scalar field in curved space. We compute the beta functions
within a generalized DeWitt-Schwinger subtraction procedure and discuss the
decoupling in the running of the coupling constants. For the case of a
quantized scalar field, all the beta function exhibit decoupling, including
also the gravitational ones. For a quantized Dirac field, decoupling appears
almost for all the beta functions. We obtain the anomalous result that the mass
of the background scalar field does not decouple.
|
[
"gr-qc",
"hep-th"
] |
gr-qc
|
hep-th
|
General Relativity and Quantum Cosmology;High Energy Physics - Theory
| 2,746General Relativity and Quantum Cosmology;High Energy Physics - Theory
|
2106.09220
|
Under the validity of the positive mass theorem, the Yamabe flow on a smooth
compact Riemannian manifold of dimension $N \ge 3$ is known to exist for all
time $t$ and converges to a solution to the Yamabe problem as $t \to \infty$.
We prove that if a suitable perturbation, which may be smooth and arbitrarily
small, is imposed on the Yamabe flow on any given Riemannian manifold $M$ of
dimension $N \ge 5$, the resulting flow may blow up at multiple points on $M$
in the infinite time. Our proof is constructive, and indeed we construct such a
flow by using solutions of the Yamabe problem on the unit sphere $\mathbb{S}^N$
as blow-up profiles. We also examine the stability of the blow-up phenomena
under a negativity condition on the Ricci curvature at blow-up points.
|
[
"math.AP",
"math.DG"
] |
math.AP
|
math.DG
|
Analysis of PDEs;Differential Geometry
| 224Analysis of PDEs;Differential Geometry
|
1212.6260
|
Detailed deducing of formulas for longitudinal electric conductivity and
dielectric permeability in the quantum degenerate collisional plasma with
constant collision frequency in Mermin' approach is given. The kinetic
Schr\"{o}dinger-Boltzmann equation in momentum space in relaxation
approximation is used. It is shown that when collision frequency of plasma
particles tends to zero (plasma passes to collisionless one), the deduced
formula for dielectric function passes to the known Lindhard' formula for
collisionless plasmas. It is shown that the deduced formula for dielectric
permeability coincides with known Mermin's formula. Graphic research of the
real and imaginary parts of dielectric function is made. Graphic comparison of
the real and imaginary parts of dielectric function for quantum and classical
plasma also is made. The module of derivative dielectric function also has been
investigated graphically.
|
[
"physics.plasm-ph",
"quant-ph"
] |
physics.plasm-ph
|
quant-ph
|
Plasma Physics;Quantum Physics
| 5,600Plasma Physics;Quantum Physics
|
astro-ph/9805194
|
I present a specific worked example of evolution through inflation to the
initial conditions for an isocurvature CDM model for structure formation. The
model invokes three scalar fields, one that drives power law inflation, one
that survives to become the present-day CDM, and one that gives the CDM field a
mass that slowly decreases during inflation and so ``tilts'' the primeval mass
fluctuation spectrum of the CDM. The functional forms for the potentials and
the parameter values that lead to an observationally acceptable model for
structure formation do not seem to be out of line with current ideas about the
physics of the very early universe. I argue in an accompanying paper that the
model offers an acceptable fit to main observational constraints.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
2107.10891
|
The paper provides a stochastic model useful for assessing the capital
requirement for demographic risk. The model extends to the market consistent
context classical methodologies developed in a local accounting framework. In
particular we provide a unique formulation for different non-participating life
insurance contracts and we prove analytically that the valuation of demographic
profit can be significantly affected by the financial conditions in the market.
A case study has been also developed considering a portfolio of life insurance
contracts. Results prove the effectiveness of the model in highlighting main
drivers of capital requirement evaluation, also compared to local GAAP
framework.
|
[
"q-fin.RM"
] |
q-fin.RM
|
Risk Management
| 6,311Risk Management
|
|
astro-ph/0212519
|
We examine the stability of self-similar solutions for an accelerating
relativistic blast wave which is generated by a point explosion in an external
medium with a steep radial density profile of a power-law index > 4.134. These
accelerating solutions apply, for example, to the breakout of a gamma-ray burst
outflow from the boundary of a massive star, as assumed in the popular
collapsar model. We show that short wavelength perturbations may grow but only
by a modest factor <~ 10.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
2112.05454
|
It is known that the deconfining transition of QCD is accompanied by the
appearance of localized eigenmodes at the low end of the Dirac spectrum. In the
quenched case localization appears exactly at the critical temperature of
deconfinement. In the present work, using quenched simulations exactly at the
critical temperature, we show that the localization properties of low Dirac
modes change abruptly between the confined and deconfined phase. This means
that in the real Polyakov loop sector, the mobility edge has a discontinuity at
the critical temperature. In contrast, in the complex sector, there is no such
discontinuity at $T_c$, even the lowest Dirac modes remain delocalized at the
critical temperature in the deconfined phase.
|
[
"hep-lat",
"hep-ph",
"hep-th"
] |
hep-lat
|
hep-ph
|
High Energy Physics - Lattice;High Energy Physics - Phenomenology;High Energy Physics - Theory
| 3,106High Energy Physics - Lattice;High Energy Physics - Phenomenology;High Energy Physics - Theory
|
1201.3816
|
Let $\nu\in M^1([0,\infty[)$ be a fixed probability measure. For each
dimension $p\in\b N$, let $(X_n^p)_{n\ge1}$ be i.i.d. $\b R^p$-valued radial
random variables with radial distribution $\nu$. We derive two central limit
theorems for $ \|X_1^p+...+X_n^p\|_2$ for $n,p\to\infty$ with normal limits.
The first CLT for $n>>p$ follows from known estimates of convergence in the CLT
on $\b R^p$, while the second CLT for $n<<p$ will be a consequence of
asymptotic properties of Bessel convolutions. Both limit theorems are
considered also for $U(p)$-invariant random walks on the space of $p\times q$
matrices instead of $\b R^p$ for $p\to\infty$ and fixed dimension $q$.
|
[
"math.PR",
"math.CA"
] |
math.PR
|
math.CA
|
Probability;Classical Analysis and ODEs
| 5,721Probability;Classical Analysis and ODEs
|
2109.12589
|
We study the role of atomic hydrogen (HI) in regulating size growth of local
galaxies. The size of a galaxy, $D_{\rm r,~25}$, is characterized by the
diameter at which the $r-$band surface brightness reaches $\mu_{\rm r}=25.0~\rm
mag~arcsec^{-2}$. We find that the positions of galaxies in the size ($D_{\rm
r,~25}$)$-$stellar mass ($M_{\ast}$) plane strongly depend on their
HI-to-stellar mass ratio ($M_{\rm HI}/M_{\ast}$). In the HI-rich regime,
galaxies that are more rich in HI tend to have larger sizes. Such a trend is
not seen in the HI-poor regime, suggesting that size growth is barely affected
by the HI content when it has declined to a sufficiently low level. An
investigation of the relations between size, $M_{\rm HI}/M_{\ast}$ and star
formation rate (SFR) suggests that size is more intrinsically linked with
$M_{\rm HI}/M_{\ast}$, rather than SFR. We further examine the HI-to-stellar
disk size ratio ($D_{\rm HI}/D_{\rm r,~25}$) of galaxies and find that at
log($M_{\rm HI}/M_{\ast})>-0.7$, $D_{\rm HI}/D_{\rm r,~25}$ is weakly
correlated with $M_{\ast}$. These findings support a picture in which the
HI-rich galaxies live in an inside-out disk growing phase regulated by gas
accretion and star formation. The angular momentum of the accreted materials is
probably the key parameter in shaping the size of an HI-rich galaxy.
|
[
"astro-ph.GA",
"astro-ph.CO"
] |
astro-ph.GA
|
astro-ph.CO
|
Astrophysics of Galaxies;Cosmology and Nongalactic Astrophysics
| 470Astrophysics of Galaxies;Cosmology and Nongalactic Astrophysics
|
2106.00267
|
Object orientation has become the predominant paradigm for conceptual
modeling (e.g., UML), where the notions of class and object form the primitive
building blocks of thought. Classes act as templates for objects that have
attributes and methods (actions). The modeled systems are not even necessarily
software systems: They can be human and artificial systems of many different
kinds (e.g., teaching and learning systems). The UML class diagram is described
as a central component of model-driven software development. It is the most
common diagram in object-oriented models and used to model the static design
view of a system. Objects both carry data and execute actions. According to
some authorities in modeling, a certain degree of difficulty exists in
understanding the semantics of these notions in UML class diagrams. Some
researchers claim class diagrams have limited use for conceptual analysis and
that they are best used for logical design. Performing conceptual analysis
should not concern the ways facts are grouped into structures. Whether a fact
will end up in the design as an attribute is not a conceptual issue. UML leads
to drilling down into physical design details (e.g., private/public attributes,
encapsulated operations, and navigating direction of an association). This
paper is a venture to further the understanding of object-orientated concepts
as exemplified in UML with the aim of developing a broad comprehension of
conceptual modeling fundamentals. Thinging machine (TM) modeling is a new
modeling language employed in such an undertaking. TM modeling interlaces
structure (components) and actionality where actions infiltrate the attributes
as much as the classes. Although space limitations affect some aspects of the
class diagram, the concluding assessment of this study reveals the class
description is a kind of shorthand for a richer sematic TM construct.
|
[
"cs.SE"
] |
cs.SE
|
Software Engineering
| 6,626Software Engineering
|
|
1602.05760
|
We propose a new three-dimensional map that demonstrates the two- and
three-frequency quasi-periodicity. For this map all basic quasi-periodic
bifurcations are possible. The study was realized by using method of Lyapunov
charts completed by plots of Lyapunov exponents, phase portraits and
bifurcation trees illustrating the quasi-periodic bifurcations. The features of
the three-parameter structure associated with quasi-periodic Hopf bifurcation
are discussed. The comparison with non-autonomous model is carried out.
|
[
"nlin.CD"
] |
nlin.CD
|
Chaotic Dynamics
| 810Chaotic Dynamics
|
|
2202.06783
|
We establish a general condition on the cost function to obtain uniqueness
and Monge solutions in the multi-marginal optimal transport problem, under the
assumption that a given collection of the marginals are absolutely continuous
with respect to local coordinates. When only the first marginal is assumed to
be absolutely continuous, our condition is equivalent to the twist on splitting
sets condition found in [23]. In addition, it is satisfied by the special cost
functions in our earlier work [32, 33], when absolute continuity is imposed on
certain other collections of marginals. We also present several new examples of
cost functions which violate the twist on splitting sets condition but satisfy
the new condition introduced here; we therefore obtain Monge solution and
uniqueness results for these cost functions, under regularity conditions on an
appropriate subset of the marginals.
|
[
"math.OC"
] |
math.OC
|
Optimization and Control
| 5,234Optimization and Control
|
|
hep-ph/9512444
|
If neutrinos have mass, we give reasons for a possible pattern of three
(squared) mass eigenvalues: $m_1^2 \simeq (2.8 - 5.8) \, \mbox{(eV)}^2 $,
$m_2^2 \simeq 0.01 \, \mbox{(eV)}^2 $, $m_3^2 \simeq (1.5 - 1) \times 10^{-4}
\mbox{(eV)}^2 $. The flavor states $\nu_{\mu} $ and $\nu_e $ are mixtures of
the eigen\-states with $m_2 $ and $m_3 $ with a significant mixing,
corresponding to an effective mixing angle of about 0.45. The $\nu_{\tau} $ is
nearly the state with $m_1 $; the other two effective mixing angles are about
an order of magnitude smaller than 0.45. There is a marked similarity to mixing
in the quark sector.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
2304.11642
|
Over the last few years, there has been an increasing interest in sub-solar
mass black holes due to their potential to provide valuable information about
cosmology or the black hole population. Motivated by this, we study observable
phenomena connected to the merger of a sub-solar mass black hole with a neutron
star. For this purpose, we perform new numerical-relativity simulations of a
binary system composed of a black hole with mass $0.5M_\odot$ and a neutron
star with mass $1.4 M_\odot$. We investigate the merger dynamics of this exotic
system and provide information about the connected gravitational-wave and
kilonova signals. Our study indicates that current gravitational-waveform
models are unable to adequately describe such systems and that phenomenological
relations connecting the binary parameters with the ejecta and remnant
properties are not applicable to our system. Furthermore, we find a dependence
of the kilonova signal on the azimuthal viewing angle due to the asymmetric
mass ejection. This first-of-its-kind simulation opens the door for the study
of sub-solar mass black hole - neutron star mergers and could serve as a
testing ground for future model development.
|
[
"gr-qc",
"astro-ph.HE"
] |
gr-qc
|
astro-ph.HE
|
General Relativity and Quantum Cosmology;High Energy Astrophysical Phenomena
| 2,729General Relativity and Quantum Cosmology;High Energy Astrophysical Phenomena
|
2007.10758
|
This paper studies continuous-time optimal contracting in a hierarchy problem
which generalises the model of Sung (2015). The hierarchy is modeled by a
series of interlinked principal-agent problems, leading to a sequence of
Stackelberg equilibria. More precisely, the principal can contract with the
managers to incentivise them to act in her best interest, despite only
observing the net benefits of the total hierarchy. Managers in turn subcontract
with the agents below them. Both agents and managers independently control in
continuous time a stochastic process representing their outcome. First, we show
through a continuous-time adaptation of Sung's model that, even if the agents
only control the drift of their outcome, their manager controls the volatility
of their continuation utility. This first simple example justifies the use of
recent results on optimal contracting for drift and volatility control, and
therefore the theory of second-order backward stochastic differential
equations, developed in the theoretical part of this paper, dedicated to a more
general model. The comprehensive approach we outline highlights the benefits of
considering a continuous-time model and opens the way to obtain comparative
statics. We also explain how the model can be extended to a large-scale
principal-agent hierarchy. Since the principal's problem can be reduced to only
an $m$-dimensional state space and a $2m$-dimensional control set, where $m$ is
the number of managers immediately below her, and is therefore independent of
the size of the hierarchy below these managers, the dimension of the problem
does not explode.
|
[
"math.OC",
"econ.TH",
"math.PR"
] |
math.OC
|
econ.TH
|
Optimization and Control;Theoretical Economics;Probability
| 7,267longtail
|
cond-mat/0602019
|
We study the transport properties of a quantum dot (QD) with highly resistive
gate electrodes, and show that the QD displays a quantum phase transition
analogous to the famous dissipative phase transition first identified by S.
Chakravarty [Phys. Rev. Lett. {\bf 49}, 681 (1982)]; for a review see [A. J.
Leggett {\em et al.}, Rev. Mod. Phys. {\bf 59}, 1 (1987)]. At temperature T=0,
the charge on the central island of a conventional QD changes smoothly as a
function of gate voltage, due to quantum fluctuations. However, for
sufficiently large gate resistance charge fluctuations on the island can freeze
out even at the degeneracy point, causing the charge on the island to change in
sharp steps as a function of gate voltage. For $R_g<R_C$ the steps remain
smeared out by quantum fluctuations. The Coulomb blockade peaks in conductance
display anomalous scaling at intermediate temperatures, and at very low
temperatures a sharp step develops in the QD conductance.
|
[
"cond-mat.mes-hall",
"cond-mat.str-el"
] |
cond-mat.mes-hall
|
cond-mat.str-el
|
Mesoscale and Nanoscale Physics;Strongly Correlated Electrons
| 4,545Mesoscale and Nanoscale Physics;Strongly Correlated Electrons
|
1902.02049
|
In this paper, we are interested in the decomposition of the tensor product
of two representations of a symmetrizable Kac-Moody Lie algebra g, and more
precisely in the tensor cone of g. Let P + be the set of dominant integral
weights. For $\lambda$ $\in$ P + , L($\lambda$) denotes the (irreducible)
integrable, highest weight representation of g with highest weight $\lambda$.
Let P +,Q be the rational convex cone generated by P +. Consider the tensor
cone $\Gamma$(g) := {($\lambda$ 1 , $\lambda$ 2 , $\mu$) $\in$ P 3 +,Q :
$\exists$N $\ge$ 1 such that L(N$\mu$) $\subset$ L(N$\lambda$
1)$\otimes$L(N$\lambda$ 2)}. If g is finite dimensional, $\Gamma$(g) is a
polyhedral convex cone described in [BK06] by an explicit finite list of
inequalities. In [Res10] this list of inequalities is proved to be irredundant:
each inequality corresponds to a codimension one face. In general, $\Gamma$(g)
is neither polyhedral, nor closed. Brown-Kumar [BK14] obtained a list of
inequalities that describe $\Gamma$(g) conjecturally. Here, we prove that each
of Brown-Kumar's inequalities corresponds to a codimension one face of
$\Gamma$(g).
|
[
"math.AG",
"math.RT"
] |
math.AG
|
math.RT
|
Algebraic Geometry;Representation Theory
| 149Algebraic Geometry;Representation Theory
|
1509.03644
|
We investigate in this short article the fundamental function for the
so-called Grand Lebesgue Spaces (GLS) and show in particular a one-to-one and
mutually continuous accordance between its fundamental and generating function.
|
[
"math.FA"
] |
math.FA
|
Functional Analysis
| 2,549Functional Analysis
|
|
0904.4603
|
The origin of the cooperative Jahn-Teller distortion and orbital-order in
LaMnO3 is central to the physics of the manganites. The question is complicated
by the simultaneous presence of tetragonal and GdFeO3-type distortions and the
strong Hund's rule coupling between e_g and t_2g electrons. To clarify the
situation we calculate the transition temperature for the Kugel-Khomskii
superexchange mechanism by using the local density approximation+dynamical
mean-field method, and disentangle the effects of super-exchange from those of
lattice distortions. We find that super-exchange alone would yield T_KK=650 K.
The tetragonal and GdFeO3-type distortions, however, reduce T_KK to 550 K. Thus
electron-phonon coupling is essential to explain the persistence of local
Jahn-Teller distortions to at least 1150 K and to reproduce the occupied
orbital deduced from neutron scattering.
|
[
"cond-mat.str-el",
"cond-mat.mtrl-sci"
] |
cond-mat.str-el
|
cond-mat.mtrl-sci
|
Strongly Correlated Electrons;Materials Science
| 7,006Strongly Correlated Electrons;Materials Science
|
1810.12879
|
We explore the perspectives of machine learning techniques in the context of
quantum field theories. In particular, we discuss two-dimensional complex
scalar field theory at nonzero temperature and chemical potential -- a theory
with a nontrivial phase diagram. A neural network is successfully trained to
recognize the different phases of this system and to predict the value of
various observables, based on the field configurations. We analyze a broad
range of chemical potentials and find that the network is robust and able to
recognize patterns far away from the point where it was trained. Aside from the
regressive analysis, which belongs to supervised learning, an unsupervised
generative network is proposed to produce new quantum field configurations that
follow a specific distribution. An implicit local constraint fulfilled by the
physical configurations was found to be automatically captured by our
generative model. We elaborate on potential uses of such a generative approach
for sampling outside the training region.
|
[
"hep-lat",
"hep-ph",
"physics.data-an"
] |
hep-lat
|
hep-ph
|
High Energy Physics - Lattice;High Energy Physics - Phenomenology;Data Analysis, Statistics and Probability
| 7,267longtail
|
1609.05147
|
In February 2014, the SHARK-VIS (System for High contrast And coronography
from R to K at VISual bands) Forerunner, a high contrast experimental imager
operating at visible wavelengths, was installed at LBT (Large Binocular
Telescope). Here we report on the first results obtained by recent on-sky
tests. These results show the extremely good performance of the LBT ExAO
(Extreme Adaptive Optics) system at visible wavelengths, both in terms of
spatial resolution and contrast achieved. Similarly to what was done by (Amara
et al. 2012), we used the SHARK-VIS Forerunner data to quantitatively assess
the contrast enhancement. This is done by injecting several different synthetic
faint objects in the acquired data and applying the ADI (angular differential
imaging) technique. A contrast of the order of $5 \times 10^{-5}$ is obtained
at 630 nm for angular separations from the star larger than 100 mas. These
results are discussed in light of the future development of SHARK-VIS and
compared to those obtained by other high contrast imagers operating at similar
wavelengths.
|
[
"astro-ph.IM"
] |
astro-ph.IM
|
Instrumentation and Methods for Astrophysics
| 3,689Instrumentation and Methods for Astrophysics
|
|
2012.02394
|
Why do biased predictions arise? What interventions can prevent them? We
evaluate 8.2 million algorithmic predictions of math performance from
$\approx$400 AI engineers, each of whom developed an algorithm under a randomly
assigned experimental condition. Our treatment arms modified programmers'
incentives, training data, awareness, and/or technical knowledge of AI ethics.
We then assess out-of-sample predictions from their algorithms using randomized
audit manipulations of algorithm inputs and ground-truth math performance for
20K subjects. We find that biased predictions are mostly caused by biased
training data. However, one-third of the benefit of better training data comes
through a novel economic mechanism: Engineers exert greater effort and are more
responsive to incentives when given better training data. We also assess how
performance varies with programmers' demographic characteristics, and their
performance on a psychological test of implicit bias (IAT) concerning gender
and careers. We find no evidence that female, minority and low-IAT engineers
exhibit lower bias or discrimination in their code. However, we do find that
prediction errors are correlated within demographic groups, which creates
performance improvements through cross-demographic averaging. Finally, we
quantify the benefits and tradeoffs of practical managerial or policy
interventions such as technical advice, simple reminders, and improved
incentives for decreasing algorithmic bias.
|
[
"econ.GN",
"cs.CY",
"q-fin.EC"
] |
econ.GN
|
cs.CY
|
General Economics;Computers and Society;Economics
| 2,606General Economics;Computers and Society;Economics
|
2401.01648
|
The notion of "pseudocompactness" was introduced by Hewitt. The concept of
relatively countably compact subspaces were explored by Marjanovic to show that
a $\Psi$-space is pseudocompact.
A topological space is said to be DRC (DRS) iff it possesses a dense,
relatively countably compact (or relatively sequentially compact, respectively)
subspace.
The concept of selectively pseudocompact game Sp(X) and the selectively
sequentially pseudocompact game Ssp(X) were introduced by Dorantes-Aldama and
Shakhmatov. They explored the relationship between the existence of a winning
strategy and a stationary winning strategy for player P in these games. In
particular, they observed that there exists a stationary winning strategy in
the game Sp(X) (Ssp(X)) for Player P iff $X$ is DRC (or DRS, respectively).
In this paper we introduce natural weakening of the properties DRC and DRS: a
space $X$ is DRCo ( DRSo) iff there is a sequence $(D_n:n \in { \omega})$ of
dense subsets of $X$ such that every sequence $(d_n:n \in { \omega} )$ with
$d_n \in D_n$ has an accumulation point (or contains a convergent subsequence,
respectively).
These properties are also equivalent to the existence of some limited
knowledge winning strategy on the corresponding games $Sp(X)$ and $Ssp(X)$.
Clearly, DRS implies DRC and DRSo, DRC or DRSo imply DRCo. The main part of
this paper is devoted to prove that apart from these trivial implications,
consistently there are no other implications between these properties.
|
[
"math.GN"
] |
math.GN
|
General Topology
| 2,781General Topology
|
|
1012.3524
|
We prove a result about partitioning an absolute continuous measure in
$\mathbb R^d$ into 2d equal parts by a system of cones with common vertex,
where $d$ is an odd prime power. The proof is topological and based on the
calculation of the equivariant Euler class of a certain vector bundle.
|
[
"math.CO",
"math.AT",
"math.MG"
] |
math.CO
|
math.AT
|
Combinatorics;Algebraic Topology;Metric Geometry
| 1,025Combinatorics;Algebraic Topology;Metric Geometry
|
2203.12736
|
Artificial intelligence (AI) has been widely applied to music generation
topics such as continuation, melody/harmony generation, genre transfer and
music infilling application. Although with the burst interest to apply AI to
music, there are still few interfaces for the musicians to take advantage of
the latest progress of the AI technology. This makes those tools less valuable
in practice and harder to find its advantage/drawbacks without utilizing them
in the real scenario. This work builds a max patch for interactive music
infilling application with different levels of control, including track
density/polyphony/occupation rate and bar tonal tension control. The user can
select the melody/bass/harmony track as the infilling content up to 16 bars.
The infilling algorithm is based on the author's previous work, and the
interface sends/receives messages to the AI system hosted in the cloud. This
interface lowers the barrier of AI technology and can generate different
variations of the selected content. Those results can give several alternatives
to the musicians' composition, and the interactive process realizes the value
of the AI infilling system.
|
[
"cs.SD",
"cs.HC",
"cs.MM",
"eess.AS"
] |
cs.SD
|
cs.HC
|
Sound;Human-Computer Interaction;Multimedia;Audio and Speech Processing
| 7,267longtail
|
0708.0304
|
We report improved measurements of time-dependent CP violation parameters for
$B^0(\bar{B}^0) \to J/\psi \pi^0$ decay. This analysis is based on 535 million
$B\bar{B}$ pairs accumulated at the $\Upsilon(4S)$ resonance with the Belle
detector at the KEKB asymmetric-energy e^+e^- collider. From the distribution
of proper time intervals between the two B decays, we obtain the following CP
violation parameters $\mathcal{S}_{J/\psi \pi^0} = -0.65\pm0.21
(\rm{stat})\pm0.05 (\rm{syst})$ and $\mathcal{A}_{J/\psi \pi^0} = +0.08\pm0.16
(\rm{stat})\pm0.05 (\rm{syst})$, which are consistent with Standard Model
expectations.
|
[
"hep-ex"
] |
hep-ex
|
High Energy Physics - Experiment
| 3,059High Energy Physics - Experiment
|
|
1305.2458
|
The classical Erd{\" o}s-Turan Inequality bounds how far a sequence of points
in the circle is from being equidistributed in terms of its exponential
moments. We prove an analogous inequality for all compact simply-connected
semisimple Lie groups, bounding how far a sequence is from being
equidistributed in the conjugacy classes of the group in terms of the moments
of irreducible characters.
|
[
"math.RT"
] |
math.RT
|
Representation Theory
| 6,217Representation Theory
|
|
math/0504425
|
By studying the reciprocity property of linear Diophantine systems in light
of Malcev-Neumann series, we present in this paper a new approach to and a
generalization of Stanley's monster reciprocity theorem. A formula for the
"error term" is given in the case when the system does not have the reciprocity
property. We also give a short proof of Stanley's reciprocity theorem for
linear homogeneous Diophantine systems.
|
[
"math.CO",
"math.AC"
] |
math.CO
|
math.AC
|
Combinatorics;Commutative Algebra
| 1,032Combinatorics;Commutative Algebra
|
1706.02757
|
Recognition of social signals, from human facial expressions or prosody of
speech, is a popular research topic in human-robot interaction studies. There
is also a long line of research in the spoken dialogue community that
investigates user satisfaction in relation to dialogue characteristics.
However, very little research relates a combination of multimodal social
signals and language features detected during spoken face-to-face human-robot
interaction to the resulting user perception of a robot. In this paper we show
how different emotional facial expressions of human users, in combination with
prosodic characteristics of human speech and features of human-robot dialogue,
correlate with users' impressions of the robot after a conversation. We find
that happiness in the user's recognised facial expression strongly correlates
with likeability of a robot, while dialogue-related features (such as number of
human turns or number of sentences per robot utterance) correlate with
perceiving a robot as intelligent. In addition, we show that facial expression,
emotional features, and prosody are better predictors of human ratings related
to perceived robot likeability and anthropomorphism, while linguistic and
non-linguistic features more often predict perceived robot intelligence and
interpretability. As such, these characteristics may in future be used as an
online reward signal for in-situ Reinforcement Learning based adaptive
human-robot dialogue systems.
|
[
"cs.RO",
"cs.CL",
"cs.HC"
] |
cs.RO
|
cs.CL
|
Robotics;Computation and Language;Human-Computer Interaction
| 6,353Robotics;Computation and Language;Human-Computer Interaction
|
2306.06777
|
In classification and forecasting with tabular data, one often utilizes
tree-based models. Those can be competitive with deep neural networks on
tabular data [cf. Grinsztajn et al., NeurIPS 2022, arXiv:2207.08815] and, under
some conditions, explainable. The explainability depends on the depth of the
tree and the accuracy in each leaf of the tree. Decision trees containing
leaves with unbalanced accuracy can provide misleading explanations.
Low-accuracy leaves give less valid explanations, which could be interpreted as
unfairness among explanations. Here, we train a shallow tree with the objective
of minimizing the maximum misclassification error across each leaf node. Then,
we extend each leaf with a separate tree-based model. The shallow tree provides
a global explanation, while the overall statistical performance of the shallow
tree with extended leaves improves upon decision trees of unlimited depth
trained using classical methods (e.g., CART) and is comparable to
state-of-the-art methods (e.g., well-tuned XGBoost).
|
[
"cs.LG",
"cs.AI",
"math.OC"
] |
cs.LG
|
cs.AI
|
Machine Learning;Artificial Intelligence;Optimization and Control
| 3,972Machine Learning;Artificial Intelligence;Optimization and Control
|
2011.06178
|
For the multiple Fourier series of the periodization of some radial functions
on $\mathbb{R}^d$, we investigate the behavior of the spherical partial sum. We
show the Gibbs-Wilbraham phenomenon, the Pinsky phenomenon and the third
phenomenon for the multiple Fourier series, involving the convergence
properties of them. The third phenomenon is closely related to the lattice
point problems, which is a classical theme of the analytic number theory. We
also prove that, for the case of two or three dimension, the convergence
problem on the Fourier series is equivalent to the lattice point problems in a
sense. In particular, the convergence problem at the origin in two dimension is
equivalent to Hardy's conjecture on Gauss's circle problem.
|
[
"math.FA",
"math.NT"
] |
math.FA
|
math.NT
|
Functional Analysis;Number Theory
| 2,588Functional Analysis;Number Theory
|
2201.10652
|
We introduce simple quadrature rules for the family of nonparametric
nonconforming quadrilateral element with four degrees of freedom. Our
quadrature rules are motivated by the work of Meng {\it et al.}
\cite{meng2018new}. First, we introduce a family of MVP (Mean Value
Property)-preserving four DOFs nonconforming elements on the intermediate
reference domain introduced by Meng {\it et al.}. Then we design two--points
and three--points quadrature rules on the intermediate reference domain. Under
the assumption on equal quadrature weights, the deviation from the
quadrilateral center of the Gauss points for the two points and three points
rules assumes the same quadratic polynomials with constant terms modified.
Thus, the two--points rule and three--points rule are constructed at one
stroke. The quadrature rules are asymptotically optimal as the mesh size is
sufficiently small. Several numerical experiments are carried out, which show
efficiency and convergence properties of the new quadrature rules.
|
[
"math.NA",
"cs.NA"
] |
math.NA
|
cs.NA
|
Numerical Analysis;Numerical Analysis
| 5,059Numerical Analysis;Numerical Analysis
|
1805.06285
|
We study the quantum quench dynamics in an extended version of the Dicke
model where an additional parameter allows a smooth transition to the
integrable Tavis-Cummings regime. We focus on the influence of various quantum
phases and excited-state quantum phase transitions (ESQPTs) on the survival
probability of the initial state. We show that, depending on the quench
protocol, an ESQPT can either stabilize the initial state or, on the contrary,
speed up its decay to the equilibrated regime. Quantum chaos smears out the
manifestations of ESQPTs in quench dynamics, therefore significant effects can
only be observed in integrable or weakly chaotic settings. Similar features are
present also in the post-quench dynamics of some observables.
|
[
"quant-ph"
] |
quant-ph
|
Quantum Physics
| 5,985Quantum Physics
|
|
1510.07173
|
We study nonnnegative radially symmetric solutions of the parabolic-elliptic
Keller-Segel whole space system \begin{align*}
\left\{\begin{array}{c@{\,}l@{\quad}l@{\,}c} u_{t}&=\Delta
u-\nabla\!\cdot(u\nabla v),\ &x\in\mathbb{R}^n,& t>0,\\ 0 &=\Delta v+u+f(x),\
&x\in\mathbb{R}^n,& t>0,\\ u(x,0)&=u_{0}(x),\ &x\in\mathbb{R}^n,&
\end{array}\right. \end{align*} with prototypical external signal production
\begin{align*} f(x):=\begin{cases} f_0\vert x\vert^{-\alpha},&\text{ if }\vert
x\vert \leq R-\rho,\\ 0,&\text{ if } \vert x\vert\geq R+\rho,\\ \end{cases}
\end{align*} for $R\in(0,1)$ and $\rho\in\left(0,\frac{R}{2}\right)$, which is
still integrable but not of class
$\text{L}^{\frac{n}{2}+\delta_0}(\mathbb{R}^n)$ for some $\delta_0\in[0,1)$.
For corresponding parabolic-parabolic Neumann-type boundary-value problems in
bounded domains $\Omega$, where
$f\in\text{L}^{\frac{n}{2}+\delta_0}(\Omega)\cap C^{\alpha}(\Omega)$ for some
$\delta_0\in(0,1)$ and $\alpha\in(0,1)$, it is known that the system does not
emit blow-up solutions if the quantities
$\|u_0\|_{\text{L}^{\frac{n}{2}+\delta_0}(\Omega)},
\|f\|_{\text{L}^{\frac{n}{2}+\delta_0}(\Omega)}$ and
$\|v_0\|_{\text{L}^{\theta}(\Omega)}$, for some $\theta>n$, are all bounded by
some $\varepsilon>0$ small enough.
We will show that whenever $f_0>\frac{2n}{\alpha}(n-2)(n-\alpha)$ and
$u_0\equiv c_0>0$ in $\overline{B_1(0)}$, a measure-valued global-in-time weak
solution to the system above can be constructed which blows up immediately.
Since these conditions are independent of $R\in(0,1)$ and $c_0>0$, we will thus
prove the criticality of $\delta_0=0$ for the existence of global bounded
solutions under a smallness conditions as described above.
|
[
"math.AP"
] |
math.AP
|
Analysis of PDEs
| 205Analysis of PDEs
|
|
2206.03899
|
Based on recently-taken and archival HARPS, FEROS and HIRES radial velocities
(RVs), we present evidence for a new planet orbiting the first ascent red giant
star HD33142 (with an improved mass estimate of 1.52$\pm$0.03 M$_\odot$),
already known to host two planets. We confirm the Jovian mass planets HD33142 b
and c with periods of $P_{\rm b}$ = 330.0$_{-0.4}^{+0.4}$ d and $P_{\rm c}$ =
810.2$_{-4.2}^{+3.8}$ d and minimum dynamical masses of $m_{\rm b}\sin{i}$ =
1.26$_{-0.05}^{+0.05}$ M$_{\rm Jup}$ and $m_{\rm c}\sin{i}$ =
0.89$_{-0.05}^{+0.06}$ M$_{\rm Jup}$. Furthermore, our periodogram analysis of
the precise RVs shows strong evidence for a short-period Doppler signal in the
residuals of a two-planet Keplerian fit, which we interpret as a third,
Saturn-mass planet with $m_\mathrm{d}\sin{i}$ = 0.20$_{-0.03}^{+0.02}$ M$_{\rm
Jup}$ on a close-in orbit with an orbital period of $P_{\rm d}$
=89.9$_{-0.1}^{+0.1}$ d. We study the dynamical behavior of the three-planet
system configurations with an N-body integration scheme, finding it long-term
stable with the planets alternating between low and moderate eccentricities
episodes. We also performed N-body simulations, including stellar evolution and
second-order dynamical effects such as planet-stellar tides and stellar
mass-loss on the way to the white dwarf phase. We find that planets HD33142 b,
c and d are likely to be engulfed near the tip of the red giant branch phase
due to tidal migration. These results make the HD33142 system an essential
benchmark for the planet population statistics of the multiple-planet systems
found around evolved stars.
|
[
"astro-ph.EP"
] |
astro-ph.EP
|
Earth and Planetary Astrophysics
| 2,351Earth and Planetary Astrophysics
|
|
1209.6318
|
New mixing structures between chiral generations of elementary particles at
low energy are shown in a vectorlike model with a horizontal symmetry SU(1,1).
In this framework the chiral model including odd number chiral generations is
realized via the spontaneous symmetry breaking of the horizontal symmetry. It
is shown that the Yukawa coupling matrices of chiral generations have naturally
hierarchical patterns, and in some cases the overall factors of their Yukawa
coupling matrices, e.g. the Yukawa coupling constants of the bottom quark and
tau lepton are naturally suppressed.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
2011.05058
|
Let $G$ be a finite non-abelian group and $m=|G|/|Z(G)|$. In this paper we
investigate $m$-centralizer group $G$ with cyclic center and we will prove that
if $G$ is a finite non-abelian $m$-centralizer $CA$-group, then there exists an
integer $r>1$ such that $m=2^r.$ It is also prove that if $G$ is an
$m$-centralizer non-abelian finite group which is not a $CA$-group and its
derived subgroup $G'$ is of order 2, then there exists an integer $s>1$ such
that $m=2^{2s}.$
|
[
"math.GR"
] |
math.GR
|
Group Theory
| 2,913Group Theory
|
|
0809.0650
|
N-body simulations have shown that the dynamical decay of the young (~1 Myr)
Orion Nebula cluster could be responsible for the loss of at least half of its
initial content of OB stars. This result suggests that other young stellar
systems could also lose a significant fraction of their massive stars at the
very beginning of their evolution. To confirm this expectation, we used the
Mid-Infrared Galactic Plane Survey (completed by the Midcourse Space Experiment
satellite) to search for bow shocks around a number of young ($\la$ several
Myr) clusters and OB associations. We discovered dozens of bow shocks generated
by OB stars running away from these stellar systems, supporting the idea of
significant dynamical loss of OB stars. In this paper, we report the discovery
of three bow shocks produced by O-type stars ejected from the open cluster
NGC6611 (M16). One of the bow shocks is associated with the O9.5Iab star
HD165319, which was suggested to be one of "the best examples for isolated
Galactic high-mass star formation" (de Wit et al. 2005, A&A, 437, 247).
Possible implications of our results for the origin of field OB stars are
discussed.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
2012.09277
|
The domain wall dynamics driven by an out of plane magnetic field was
measured for a series of magnetic trilayers with different strengths of the
interfacial Dzyaloshinskii-Moriya interaction (DMI). The features of the
field-driven domain wall velocity curves strongly depend on the amplitude of
the HD field stabilising chiral N\'eel walls. The measured Walker velocity,
which in systems with large DMI is maintained after the Walker field giving
rise to a velocity plateau up to the Slonczewski field HS, can be easily
related to the DMI strength. Yet, when the DMI field HD and the domain wall
demagnetising field HDW have comparable values, a careful analysis needs to be
done in order to evaluate the impact of the DMI on the domain wall velocity. By
means of a one-dimensional model and 2D simulations, we successfully extend
this method to explain experimental results to cases where HD and HDW are
comparable.
|
[
"cond-mat.mes-hall"
] |
cond-mat.mes-hall
|
Mesoscale and Nanoscale Physics
| 4,450Mesoscale and Nanoscale Physics
|
|
hep-ph/0212244
|
We study soft supersymmetry breaking parameters in a supersymmetric unified
model which potentially solves the doublet-triplet splitting problem. In the
model the doublet-triplet splitting is solved by the discrete symmetry which is
allowed to be introduced due to the direct product structure of the gauge
group. The messenger fields for the gauge mediated supersymmetry breaking are
naturally embedded in the model. The discrete symmetry required by the
doublet-triplet splitting makes the gaugino masses non-universal and also
induces a different mass spectrum for the scalar masses from the ordinary
minimal gauge mediation model. Independent physical CP phases can remain in the
gaugino sector even after the R-transformation.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
1907.08842
|
The underlying event is an important part of high-energy collision events. In
the event generators, the underlying event is tuned by fits to collision data.
Usually, the underlying event observables are affected by the existence of
extra jets and it is difficult to find a part of the phase space which is
dominated by the underlying event. In this paper, we suggest to veto the jets
in the considered region to disentangle these effects. The idea is verified to
work on CMS Open Data. To our knowledge, it is the first time that such ideas
are tested on real collision data.
|
[
"hep-ph",
"hep-ex"
] |
hep-ph
|
hep-ex
|
High Energy Physics - Phenomenology;High Energy Physics - Experiment
| 3,198High Energy Physics - Phenomenology;High Energy Physics - Experiment
|
2112.02767
|
Most of the existing methods for debaising in click-through rate (CTR)
prediction depend on an oversimplified assumption, i.e., the click probability
is the product of observation probability and relevance probability. However,
since there is a complicated interplay between these two probabilities, these
methods cannot be applied to other scenarios, e.g. query auto completion (QAC)
and route recommendation. We propose a general debiasing framework without
simplifying the relationships between variables, which can handle all scenarios
in CTR prediction. Simulation experiments show that: under the simplest
scenario, our method maintains a similar AUC with the state-of-the-art methods;
in other scenarios, our method achieves considerable improvements compared with
existing methods. Meanwhile, in online experiments, the framework also gains
significant improvements consistently.
|
[
"cs.IR",
"cs.AI"
] |
cs.IR
|
cs.AI
|
Information Retrieval;Artificial Intelligence
| 3,579Information Retrieval;Artificial Intelligence
|
1012.0931
|
Conjectures of Suciu relate the fundamental group of the complement M = C^n\A
of a hyperplane arrangement A to the first resonance variety of H^*(M,Z). We
describe a connection between the first resonance variety and the Orlik-Terao
algebra C(A) of the arrangement. In particular, we show that non-local
components of R^1(A) give rise to determinantal syzygies of C(A). As a result,
Proj(C(A)) lies on a scroll, placing geometric constraints on R^1(A). The key
observation is that C(A) is the homogeneous coordinate ring associated to a nef
but not ample divisor on the blowup of P^2 at the singular points of A.
|
[
"math.AG"
] |
math.AG
|
Algebraic Geometry
| 47Algebraic Geometry
|
|
0812.3422
|
We present results about spaces of holomorphic functions associated to the
classical Dirichlet space. The spaces we consider have roles similar to the
roles of $H^{1}$ and $BMO$ in the Hardy space theory and we emphasize those
analogies.
|
[
"math.CV",
"math.FA"
] |
math.CV
|
math.FA
|
Complex Variables;Functional Analysis
| 1,154Complex Variables;Functional Analysis
|
2101.07230
|
We present a calculation of the contribution of the $\Theta$-term to the
neutron and proton electric dipole moments using seven 2+1+1-flavor HISQ
ensembles. We also estimate the topological susceptibility for the 2+1+1 theory
to be $\chi_Q = (66(9)(4) \rm MeV)^4$ in the continuum limit at $M_\pi = 135$
MeV. The calculation of the nucleon three-point function is done using
Wilson-clover valence quarks. The CP-violating form factor $F_3$ is calculated
by expanding in small $\Theta$. We show that lattice artifacts introduce a term
proportional to $a$ that does not vanish in the chiral limit, and we include
this in our chiral-continuum fits. A chiral perturbation theory analysis shows
that the $N(0) \pi(0)$ state should provide the leading excited state
contribution, and we study the effect of such a state. Detailed analysis of the
contributions to the neutron and proton electric dipole moment using two
strategies for removing excited state contamination are presented. Using the
excited state spectrum from fits to the two-point function, we find
$d_n^\Theta$ is small, $|d_n^\Theta| \lesssim 0.01 \overline \Theta e$ fm,
whereas for the proton we get $|d_p^\Theta| \sim 0.02 \overline \Theta e$ fm.
On the other hand, if the dominant excited-state contribution is from the $N
\pi$ state, then $|d_n^\Theta|$ could be as large as $0.05 \overline \Theta e$
fm and $|d_p^\Theta| \sim 0.07 \overline \Theta e$ fm. Our overall conclusion
is that present lattice QCD calculations do not provide a reliable estimate of
the contribution of the $\Theta$-term to the nucleon electric dipole moments,
and a factor of ten higher statistics data are needed to get better control
over the systematics and possibly a $3\sigma$ result.
|
[
"hep-lat",
"hep-ph"
] |
hep-lat
|
hep-ph
|
High Energy Physics - Lattice;High Energy Physics - Phenomenology
| 3,105High Energy Physics - Lattice;High Energy Physics - Phenomenology
|
1505.04702
|
We discuss the potential impacts on the CMSSM of future LHC runs and possible
electron-positron and higher-energy proton-proton colliders, considering
searches for supersymmetry via MET events, precision electroweak physics, Higgs
measurements and dark matter searches. We validate and present estimates of the
physics reach for exclusion or discovery of supersymmetry via MET searches at
the LHC, which should cover the low-mass regions of the CMSSM parameter space
favoured in a recent global analysis. As we illustrate with a low-mass
benchmark point, a discovery would make possible accurate LHC measurements of
sparticle masses using the MT2 variable, which could be combined with
cross-section and other measurements to constrain the gluino, squark and stop
masses and hence the soft supersymmetry-breaking parameters m_0, m_{1/2} and
A_0 of the CMSSM. Slepton measurements at CLIC would enable m_0 and m_{1/2} to
be determined with high precision. If supersymmetry is indeed discovered in the
low-mass region, precision electroweak and Higgs measurements with a future
circular electron-positron collider (FCC-ee, also known as TLEP) combined with
LHC measurements would provide tests of the CMSSM at the loop level. If
supersymmetry is not discovered at the LHC, is likely to lie somewhere along a
focus-point, stop coannihilation strip or direct-channel A/H resonance funnel.
We discuss the prospects for discovering supersymmetry along these strips at a
future circular proton-proton collider such as FCC-hh. Illustrative benchmark
points on these strips indicate that also in this case FCC-ee could provide
tests of the CMSSM at the loop level.
|
[
"hep-ph",
"hep-ex"
] |
hep-ph
|
hep-ex
|
High Energy Physics - Phenomenology;High Energy Physics - Experiment
| 3,198High Energy Physics - Phenomenology;High Energy Physics - Experiment
|
hep-th/0206109
|
We study non-supersymmetric orbifold singularities from the point of view of
D-brane probes. We present a description of the decay of such singularities
from considerations of the toric geometry of the probe branes.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
2112.11235
|
Adversarial robustness is one of the most challenging problems in Deep
Learning and Computer Vision research. All the state-of-the-art techniques
require a time-consuming procedure that creates cleverly perturbed images. Due
to its cost, many solutions have been proposed to avoid Adversarial Training.
However, all these attempts proved ineffective as the attacker manages to
exploit spurious correlations among pixels to trigger brittle features
implicitly learned by the model. This paper first introduces a new image
filtering scheme called Image-Graph Extractor (IGE) that extracts the
fundamental nodes of an image and their connections through a graph structure.
By leveraging the IGE representation, we build a new defense method, Filtering
As a Defense, that does not allow the attacker to entangle pixels to create
malicious patterns. Moreover, we show that data augmentation with filtered
images effectively improves the model's robustness to data corruption. We
validate our techniques on CIFAR-10, CIFAR-100, and ImageNet.
|
[
"cs.CV"
] |
cs.CV
|
Computer Vision and Pattern Recognition
| 1,498Computer Vision and Pattern Recognition
|
|
hep-ph/0401145
|
The transverse momentum spectra of the Z and Higgs bosons are studied, as
probes of the consequences of multiple parton emissions in hadronic events.
Emphasis is put on constraints, present in showers, that go beyond conventional
leading log. It is shown that, if such constraints are relaxed, better
agreement can be obtained with experimental data and with resummation
descriptions.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
1805.02572
|
In this work we study the space complexity of computable real numbers
represented by fast convergent Cauchy sequences. We show the existence of
families of trascendental numbers which are logspace computable, as opposed to
algebraic irrational numbers which seem to required linear space. We
characterized the complexity of space-bounded real numbers by quantifying the
space complexities of tally sets. The latter result introduces a technique to
prove the space complexity of real numbers by studying its corresponding tally
sets, which is arguably a more natural approach. Results of this work present a
new approach to study real numbers whose transcendence is unknown.
|
[
"cs.CC"
] |
cs.CC
|
Computational Complexity
| 1,280Computational Complexity
|
|
2305.14297
|
In recent years, many positivity-preserving schemes for initial value
problems have been constructed by modifying a Runge--Kutta (RK) method by
weighting the right-hand side of the system of differential equations with
solution-dependent factors. These include the classes of modified
Patankar--Runge--Kutta (MPRK) and Geometric Conservative (GeCo) methods.
Compared to traditional RK methods, the analysis of accuracy and stability of
these methods is more complicated. In this work, we provide a comprehensive and
unifying theory of order conditions for such RK-like methods, which differ from
original RK schemes in that their coefficients are solution-dependent. The
resulting order conditions are themselves solution-dependent and obtained using
the theory of NB-series, and thus, can easily be read off from labeled N-trees.
We present for the first time order conditions for MPRK and GeCo schemes of
arbitrary order; For MPRK schemes, the order conditions are given implicitly in
terms of the stages. From these results, we recover as particular cases all
known order conditions from the literature for first- and second-order GeCo as
well as first-, second- and third-order MPRK methods. Additionally, we derive
sufficient and necessary conditions in an explicit form for 3rd and 4th order
GeCo schemes as well as 4th order MPRK methods.
|
[
"math.NA",
"cs.NA"
] |
math.NA
|
cs.NA
|
Numerical Analysis;Numerical Analysis
| 5,059Numerical Analysis;Numerical Analysis
|
math/0309073
|
In this paper we prove the equivalence of two conjectures on linear systems
through fat points on a generic K3 surface. The first conjecture is exactly as
Segre conjecture on the projective plane. Whereas the second characterizes such
linear system and can be compared to the Gimigliano-Harbourne-Hirschowitz
conjecture.
|
[
"math.AG"
] |
math.AG
|
Algebraic Geometry
| 47Algebraic Geometry
|
|
hep-th/9309049
|
We show that the renormalized vacuum expectation value of the Wilson loop for
topologically massive abelian gauge theory in $\RR^3$ can be defined so that
its large-mass limit be the renormalized vacuum expectation value of the Wilson
loop for abelian Chern-Simons theory also in $\RR^3$.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
0910.3848
|
Lattice protein models, as the Hydrophobic-Polar (HP) model, are a common
abstraction to enable exhaustive studies on structure, function, or evolution
of proteins. A main issue is the high number of optimal structures, resulting
from the hydrophobicity-based energy function applied. We introduce an
equivalence relation on protein structures that correlates to the energy
function. We discuss the efficient enumeration of optimal representatives of
the corresponding equivalence classes and the application of the results.
|
[
"cs.CE",
"q-bio.BM"
] |
cs.CE
|
q-bio.BM
|
Computational Engineering, Finance, and Science;Biomolecules
| 1,316Computational Engineering, Finance, and Science;Biomolecules
|
hep-ph/0407020
|
The properties of cosmic rays with energies above 10**6 GeV have to be
deduced from the spacetime structure and particle content of the air showers
which they initiate. In this review we summarize the phenomenology of these
giant air showers. We describe the hadronic interaction models used to
extrapolate results from collider data to ultra high energies, and discuss the
prospects for insights into forward physics at the LHC. We also describe the
main electromagnetic processes that govern the longitudinal shower evolution,
as well as the lateral spread of particles. Armed with these two principal
shower ingredients and motivation from the underlying physics, we provide an
overview of some of the different methods proposed to distinguish primary
species. The properties of neutrino interactions and the potential of
forthcoming experiments to isolate deeply penetrating showers from baryonic
cascades are also discussed. We finally venture into a terra incognita endowed
with TeV-scale gravity and explore anomalous neutrino-induced showers.
|
[
"hep-ph",
"astro-ph",
"hep-th"
] |
hep-ph
|
astro-ph
|
High Energy Physics - Phenomenology;Astrophysics;High Energy Physics - Theory
| 3,143High Energy Physics - Phenomenology;Astrophysics;High Energy Physics - Theory
|
1608.04724
|
Levitated nanodiamonds containing nitrogen vacancy centres in high vacuum are
a potential test bed for numerous phenomena in fundamental physics. However,
experiments so far have been limited to low vacuum due to heating arising from
optical absorption of the trapping laser. We show that milling pure diamond
creates nanodiamonds that do not heat up as the optical intensity is raised
above 700 GW/m$^2$ below 5 mbar of pressure. This advance now means that the
level of attainable vacuum for nanodiamonds in optical dipole traps is no
longer temperature limited.
|
[
"physics.optics",
"cond-mat.mes-hall",
"cond-mat.mtrl-sci",
"quant-ph"
] |
physics.optics
|
cond-mat.mes-hall
|
Optics;Mesoscale and Nanoscale Physics;Materials Science;Quantum Physics
| 5,209Optics;Mesoscale and Nanoscale Physics;Materials Science;Quantum Physics
|
1702.06605
|
Weak amenability of a weighted group algebra, or a Beurling algebra, is a
long-standing open problem. The commutative case has been extensively
investigated and fully characterized. We study the non-commutative case. Given
a weight function $\omega$ on a locally compact group $G$, we characterize
derivations from $L^1(G,\omega)$ into its dual in terms of certain functions.
Then we show that for a locally compact IN group $G$, if there is a non-zero
continuous group homomorphism $\varphi$: $G\to \mathbb{C}$ such that
$\varphi(x)/\omega(x)\omega(x^{-1})$ is bounded on $G$, then $L^1(G,\omega)$ is
not weakly amenable. Some useful criteria that rule out weak amenability of
$L^1(G,\omega)$ are established. Using them we show that for many polynomial
type weights the weighted Heisenberg group algebra is not weakly amenable,
neither is the weighted $\boldsymbol{ax+b}$ group algebra. We further study
weighted quotient group algebra $L^1(G/H,\hat\omega)$, where $\hat\omega$ is
the canonical weight on $G/H$ induced by $\omega$. We reveal that the kernel of
the canonical homomorphism from $L^1(G,\omega)$ to $L^1(G/H,\hat\omega)$ is
complemented. This allows us to obtain some sufficient conditions under which
$L^1(G/H,\hat\omega)$ inherits weak amenability of $L^1(G,\omega)$. We study
further weak amenability of Beurling algebras of subgroups. In general, weak
amenability of a Beurling algebra does not pass to the Beurling algebra of a
subgroup. However, in some circumstances this inheritance can happen. We also
give an example to show that weak amenability of both $L^1(H,\omega|_H)$ and
$L^1(G/H,\hat\omega)$ does not ensure weak amenability of $L^1(G,\omega)$.
|
[
"math.FA"
] |
math.FA
|
Functional Analysis
| 2,549Functional Analysis
|
|
cond-mat/0603187
|
Two conformations of isolated single TBrPP-Co molecules on a Cu(111) surface
are switched by applying +2.2 V voltage pulses from a scanning tunneling
microscope tip at 4.6 K. The TBrPP-Co has a spin-active cobalt atom caged at
its center and the interaction between the spin of this cobalt atom and free
electrons from the Cu(111) substrate can cause a Kondo resonance. Tunneling
spectroscopy data reveal that switching from the saddle to a planar molecular
conformation enhances spin-electron coupling, which increases the associated
Kondo temperature from 130 K to 170 K. This result demonstrates that the Kondo
temperature can be manipulated just by changing molecular conformation without
altering chemical composition of the molecule.
|
[
"cond-mat.mtrl-sci"
] |
cond-mat.mtrl-sci
|
Materials Science
| 4,287Materials Science
|
|
1907.12607
|
Conventional approaches to probing ultrafast molecular dynamics rely on the
use of synchronized laser pulses with a well-defined time delay. Typically, a
pump pulse excites a wavepacket in the molecule. A subsequent probe pulse can
then dissociates or ionizes the molecule, and measurement of the molecular
fragments provides information about where the wavepacket was for each time
delay. In this work, we propose to exploit the ultrafast
nuclear-position-dependent emission obtained due to large light-matter coupling
in plasmonic nanocavities to image wavepacket dynamics using only a single pump
pulse. We show that the time-resolved emission from the cavity provides
information about when the wavepacket passes a given region in nuclear
configuration space. This approach can image both cavity-modified dynamics on
polaritonic (hybrid light-matter) potentials in the strong light-matter
coupling regime as well as bare-molecule dynamics in the intermediate coupling
regime of large Purcell enhancements, and provides a new route towards
ultrafast molecular spectroscopy with plasmonic nanocavities.
|
[
"cond-mat.mes-hall",
"physics.chem-ph",
"quant-ph"
] |
cond-mat.mes-hall
|
physics.chem-ph
|
Mesoscale and Nanoscale Physics;Chemical Physics;Quantum Physics
| 4,466Mesoscale and Nanoscale Physics;Chemical Physics;Quantum Physics
|
1212.6653
|
We study the disorder potential induced by random Coulomb impurities at the
surface of a topological insulator (TI). We use a simple model in which
positive and negative impurities are distributed uniformly throughout the bulk
of the TI, and we derive the magnitude of the disorder potential at the TI
surface using a self-consistent theory based on the Thomas-Fermi approximation
for screening by the Dirac mode. Simple formulas are presented for the mean
squared potential both at the Dirac point and far from it, as well as for the
characteristic size of electron/hole puddles at the Dirac point and the total
concentration of electrons/holes that they contain. We also derive an
expression for the autocorrelation function for the potential at the surface
and show that it has an unusually slow decay, which can be used to verify the
bulk origin of disorder. The implications of our model for the electron
conductivity of the surface are also presented.
|
[
"cond-mat.mes-hall",
"cond-mat.dis-nn"
] |
cond-mat.mes-hall
|
cond-mat.dis-nn
|
Mesoscale and Nanoscale Physics;Disordered Systems and Neural Networks
| 4,471Mesoscale and Nanoscale Physics;Disordered Systems and Neural Networks
|
1207.3003
|
The Swift era has posed a challenge to the standard blast-wave model of Gamma
Ray Burst (GRB) afterglows. The key observational features expected within the
model are rarely observed, such as the achromatic steepening (`jet-break') of
the light curves. The observed afterglow light curves showcase additional
complex features requiring modifications within the standard model. Here we
present optical/NIR observations, millimeter upper limits and comprehensive
broadband modelling of the afterglow of the bright GRB 0505025A, detected by
Swift. This afterglow cannot be explained by the simplistic form of the
standard blast-wave model. We attempt modelling the multi-wavelength light
curves using (i) a forward-reverse shock model, (ii) a two-component outflow
model and (iii) blast-wave model with a wind termination shock. The
forward-reverse shock model cannot explain the evolution of the afterglow. The
two component model is able to explain the average behaviour of the afterglow
very well but cannot reproduce the fluctuations in the early X-ray light curve.
The wind termination shock model reproduces the early light curves well but
deviates from the global behaviour of the late-time afterglow.
|
[
"astro-ph.HE"
] |
astro-ph.HE
|
High Energy Astrophysical Phenomena
| 2,990High Energy Astrophysical Phenomena
|
|
cond-mat/0606063
|
Basic experimental facts related to ARPES, tunnelling, optics ad neutron
scattering measurements are discussed. They give evidence for the relevance of
the electron-phonon interaction (EPI) in pairing mechanism of HTSC cuprates. A
controllable theory for strong correlations and their effects on EPI is
discussed which is based on the 1/N expansion method in the t-J model. Strong
correlations renormalize EPI and other charge-fluctuation properties (by
including nonmagnetic impurity scattering) and the forward scattering peak
(FSP) appears in the effective interactions. Pronounced FSP in EPI of HTSC
cuprates reconciles many puzzling results. The theory of EPI with FSP gives
that the couplings in the s- and d-wave pairing channel are of the same
magnitude near and below the optimal hole doping. FSP in the nonmagnetic
impurity scattering potential is responsible for robustness of d-wave pairing
in cuprates. The ARPES kink and the isotope effect in the nodal and anti-nodal
points and the collapse of the elastic impurity scattering in the
superconducting state, are explained by this theory. It also explains why the
nodal kink is not-shifted in the superconducting state while the anti-nodal
kink is shifted by the maximal superconducting gap. In systems with FSP in EPI
besides the classical phase fluctuations there are also internal fluctuations
of Cooper pairs giving rise to an additional contribution to the pseudogap.
|
[
"cond-mat.supr-con"
] |
cond-mat.supr-con
|
Superconductivity
| 7,066Superconductivity
|
|
astro-ph/0411560
|
The gapless color-flavor locked (gCFL) phase is the second-densest phase of
matter in the QCD phase diagram, making it a plausible constituent of the core
of neutron stars. We show that even a relatively small region of gCFL matter in
a star will dominate both the heat capacity C_V and the heat loss by neutrino
emission L_\nu. The gCFL phase is characterized by an unusual quasiparticle
dispersion relation that makes both its specific heat c_V and its neutrino
emissivity epsilon_\nu parametrically larger than in any other phase of nuclear
or quark matter. During the epoch in which the cooling of the star is dominated
by direct Urca neutrino emission, the presence of a gCFL region does not
strongly alter the cooling history because the enhancements of C_V and L_\nu
cancel against each other. At late times, however, the cooling is dominated by
photon emission from the surface, so L_\nu is irrelevant, and the anomalously
large heat capacity of the gCFL region keeps the star warm. The temperature
drops with time as T\sim t^{-1.4} rather than the canonical T\sim t^{-5}. This
provides a unique and potentially observable signature of gCFL quark matter.
|
[
"astro-ph",
"hep-ph",
"nucl-th"
] |
astro-ph
|
hep-ph
|
Astrophysics;High Energy Physics - Phenomenology;Nuclear Theory
| 532Astrophysics;High Energy Physics - Phenomenology;Nuclear Theory
|
1811.03708
|
Questions of geography of various classes of $4$-manifolds have been a
central motivating question in $4$-manifold topology. Baykur and Korkmaz asked
which small, simply connected, minimal $4$-manifolds admit a genus $2$
Lefschetz fibration. They were able to classify all the possible homeomorphism
types and realize all but one with the exception of a genus $2$ Lefschetz
fibration on a symplectic $4$-manifold homeomorphic, but not diffeomorphic to
$3 \mathbb{CP}^2 \# 11\overline{\mathbb{CP}}^2$. We give a positive
factorization of type $(10,10)$ that corresponds to such a genus $2$ Lefschetz
fibration. Furthermore, we observe two restrictions on the geography of genus
$2$ Lefschetz fibrations, we find that they satisfy the Noether inequality and
a BMY like inequality. We then find positive factorizations that describe genus
$2$ Lefschetz fibrations on simply connected, minimal symplectic $4$-manifolds
for many of these points.
|
[
"math.GT",
"math.SG"
] |
math.GT
|
math.SG
|
Geometric Topology;Symplectic Geometry
| 2,864Geometric Topology;Symplectic Geometry
|
1506.04168
|
We study a queueing system with Poisson arrivals on a bus line indexed by
integers. The buses move at constant speed to the right and the time of service
per customer getting on the bus is fixed. The customers arriving at station i
wait for a bus if this latter is less than d\_i stations before, where d\_i is
non-decreasing. We determine the asymptotic behavior of a single bus and when
two buses eventually coalesce almost surely by coupling arguments. Three
regimes appear, two of which leading to a.s. coalescing of the buses.The
approach relies on a connection with aged structured branching processes with
immigration and varying environment. We need to prove a Kesten Stigum type
theorem, i.e. the a.s. convergence of the successive size of the branching
process normalized by its mean. The technics developed combines a spine
approach for multitype branching process in varying environment and geometric
ergodicity along the spine to control the increments of the normalized process.
|
[
"math.PR"
] |
math.PR
|
Probability
| 5,709Probability
|
|
1812.00122
|
In [Joyal] where the category $\Theta$ is first defined it is noted that the
dimensional shift on $\Theta$ suggests an elegant presentation of the unreduced
suspension on cellular sets. In this note we prove that the reduced suspension
associated to that presentation is left Quillen with respect to the Cisinski
model category structure presenting the $\left(\infty,1\right)$-category of
pointed spaces and enjoys the correct universal property. More, we go on to
describe how, in forthcoming work, inspired by the combinatorial spectra
described in [Kan], this suspension functor entails a description of spectra
which echoes the weaker form of the homotopy hypothesis, we describe the
development of a presentation of spectra as locally finite weak
$\mathbf{Z}$-groupoids.
|
[
"math.CT"
] |
math.CT
|
Category Theory
| 757Category Theory
|
|
hep-th/0004180
|
An $S$-matrix is proposed for the two dimensional O(3) $\sigma$-model with a
dynamical $\theta$-term (axion model). Exploiting an Abelian T-duality
transformation connecting the axion model to an integrable SU(2)$\times$U(1)
symmetric principal $\sigma$-model, strong evidence is presented for the
correctness of the proposed $S$-matrix by comparing the perturbatively
calculated free energies with the ones based on the Thermodynamical Bethe
Ansatz. This T-duality transformation also leads to a new Lax-pair for both
models. The quantum non-integrability of the O(3) $\sigma$-model with a {\sl
constant} $\theta$-term, in contradistinction to the axion model, is
illustrated by calculating the $2\to3$ particle production amplitude to lowest
order in $\theta$.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
1008.3526
|
Globular clusters are useful to test the validity of Newtonian dynamics in
the low acceleration regime typical of galaxies, without the complications of
non-baryonic dark matter. Specifically, in absence of disturbing effects, e.g.
tidal heating, their velocity dispersion is expected to vanish at large radii.
If such behaviour is not observed, and in particular if, as observed in
elliptical galaxies, the dispersion is found constant at large radii below a
certain threshold acceleration, this might indicate a break down of Newtonian
dynamics.
To minimise the effects of tidal heating in this paper we study the velocity
dispersion profile of two distant globular clusters, NGC 1851 and NGC 1904.
The velocity dispersion profile is derived from accurate radial velocities
measurements, obtained at the ESO 8m VLT telescope. Reliable data for 184 and
146 bona fide cluster star members, respectively for NGC 1851 and NGC 1904,
were obtained.
These data allow to trace the velocity dispersion profile up to ~2r0, where
r0 is the radius at which the cluster internal acceleration of gravity is a0 =
10e-8 cm/s/s. It is found that in both clusters the velocity dispersion becomes
constant beyond ~r0. These new results are fully in agreement with those found
for other five globular clusters previously investigated as part of this
project. Taken all together, these 7 clusters support the claim that the
velocity dispersion is constant beyond r0, irrespectively of the specific
physical properties of the clusters: mass, size, dynamical history, and
distance from the Milky Way. The strong similarly with the constant velocity
dispersion observed in elliptical galaxies beyond r0 is suggestive of a common
origin for this phenomenon in the two class of objects, and might indicate a
breakdown of Newtonian dynamics below a0.
|
[
"astro-ph.GA"
] |
astro-ph.GA
|
Astrophysics of Galaxies
| 464Astrophysics of Galaxies
|
|
cs/0604060
|
Lie group theory states that knowledge of a $m$-parameters solvable group of
symmetries of a system of ordinary differential equations allows to reduce by
$m$ the number of equation. We apply this principle by finding dilatations and
translations that are Lie point symmetries of considered ordinary differential
system. By rewriting original problem in an invariant coordinates set for these
symmetries, one can reduce the involved number of parameters. This process is
classically call nondimensionalisation in dimensional analysis. We present an
algorithm based on this standpoint and show that its arithmetic complexity is
polynomial in input's size.
|
[
"cs.SC"
] |
cs.SC
|
Symbolic Computation
| 7,107Symbolic Computation
|
|
1905.03389
|
Evolution and learning are two of the fundamental mechanisms by which life
adapts in order to survive and to transcend limitations. These biological
phenomena inspired successful computational methods such as evolutionary
algorithms and deep learning. Evolution relies on random mutations and on
random genetic recombination. Here we show that learning to evolve, i.e.
learning to mutate and recombine better than at random, improves the result of
evolution in terms of fitness increase per generation and even in terms of
attainable fitness. We use deep reinforcement learning to learn to dynamically
adjust the strategy of evolutionary algorithms to varying circumstances. Our
methods outperform classical evolutionary algorithms on combinatorial and
continuous optimization problems.
|
[
"cs.NE",
"cs.AI",
"cs.CV",
"cs.LG",
"stat.ML"
] |
cs.NE
|
cs.AI
|
Neural and Evolutionary Computing;Artificial Intelligence;Computer Vision and Pattern Recognition;Machine Learning;Machine Learning
| 7,267longtail
|
2110.15437
|
The spectral theory of random walks on networks of arbitrary topology can be
readily extended to study random walks and L\'evy flights subject to resetting
on these structures. When a discrete-time process is stochastically brought
back from time to time to its starting node, the mean search time needed to
reach another node of the network may be significantly decreased. In other
cases, however, resetting is detrimental to search. Using the eigenvalues and
eigenvectors of the transition matrix defining the process without resetting,
we derive a general criterion for finite networks that establishes when there
exists a non-zero resetting probability that minimizes the mean first passage
time at a target node. Right at optimality, the coefficient of variation of the
first passage time is not unity, unlike in continuous time processes with
instantaneous resetting, but above 1 and depends on the minimal mean first
passage time. The approach is general and applicable to the study of different
discrete-time ergodic Markov processes such as L\'evy flights, where the
long-range dynamics is introduced in terms of the fractional Laplacian of the
graph. We apply these results to the study of optimal transport on rings and
Cayley trees.
|
[
"cond-mat.stat-mech"
] |
cond-mat.stat-mech
|
Statistical Mechanics
| 6,821Statistical Mechanics
|
|
astro-ph/0602171
|
A long-standing problem for models of galaxy formation has been the mismatch
between the predicted shape of the mass function of dark matter halos and the
observed shape of the luminosity function of galaxies. The number of massive
halos is predicted to decrease as a power law (N proportional to M^-2) out to
very large masses, while the galaxy luminosity function cuts off exponentially
at luminosities above L*. This implies that the efficiency with which gas cools
onto massive systems is lower than expected. This letter investigates the role
of radio-loud active galactic nuclei (AGN) in continually re-heating the
cooling gas. By combining two observational results, the time-averaged energy
output associated with recurrent radio source activity is determined, as a
function of the black hole mass of the host galaxy: H = 10^21.4 (M_BH /
M_sun)^1.6 W. It is shown that for massive elliptical galaxies this
radio-source heating balances the radiative energy losses from the hot gas
surrounding the galaxy. The recurrent radio-loud AGN activity may therefore
provide a self-regulating feedback mechanism capable of controlling the rate of
growth of galaxies.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
hep-ph/9912313
|
Starting with the vacuum fluctuation, it is known that gravitinos will be
created just after inflation, with number density $\sim 10^{-2}M^3$ where $M$
is the mass of the inflaton. Here, we argue that creation may be expected to
continue, maintaining about the same number density, until a usually much later
epoch. This epoch is either the `intermediate epoch' when Hubble parameter
falls below the gravitino mass, or the reheat epoch if that is earlier. We
verify that such late-time creation indeed occurs if only a single chiral
superfield is relevant, using the description of the helicity 1/2 gravitino
provided recently by Kallosh et. al. (hep-th/9907124) and Giudice et. al.
(hep-ph/9907510). Arguments are presented in favor of late-time creation in the
general case. For the usual inflation models, $M$ is rather large and
gravitinos from late-time creation are so abundant that a subsequent era of
thermal inflation is needed to dilute them.
|
[
"hep-ph",
"astro-ph",
"gr-qc",
"hep-th"
] |
hep-ph
|
astro-ph
|
High Energy Physics - Phenomenology;Astrophysics;General Relativity and Quantum Cosmology;High Energy Physics - Theory
| 3,137High Energy Physics - Phenomenology;Astrophysics;General Relativity and Quantum Cosmology;High Energy Physics - Theory
|
1909.01083
|
The conservation of energy and momentum have been viewed as undermining
Cartesian mental causation since the 1690s. Modern discussions of the topic
tend to use mid-19th century physics, neglecting both locality and Noether's
theorem and its converse. The relevance of General Relativity (GR) has rarely
been considered. But a few authors have proposed that the non-localizability of
gravitational energy and consequent lack of physically meaningful local
conservation laws answers the conservation objection to mental causation:
conservation already fails in GR, so there is nothing for minds to violate.
This paper is motivated by two ideas. First, one might take seriously the
fact that GR formally has an infinity of rigid symmetries of the action and
hence, by Noether's first theorem, an infinity of conserved energies-momenta
(thus answering Schr\"{o}dinger's 1918 false-negative objection). Second, Sean
Carroll has asked (rhetorically) how one should modify the
Dirac-Maxwell-Einstein equations to describe mental causation. This paper uses
the generalized Bianchi identities to show that General Relativity tends to
exclude, not facilitate, such Cartesian mental causation. In the simplest case,
Cartesian mental influence must be spatio-temporally constant, and hence 0. The
difficulty may diminish for more complicated models. Its persuasiveness is also
affected by larger world-view considerations.
The new general relativistic objection provides some support for realism
about gravitational energy-momentum in GR (taking pseudotensor laws seriously).
Such realism also answers an objection to theories of causation involving
conserved quantities, because energies-momenta would be conserved even in GR.
|
[
"physics.hist-ph",
"physics.pop-ph"
] |
physics.hist-ph
|
physics.pop-ph
|
History and Philosophy of Physics;Popular Physics
| 3,468History and Philosophy of Physics;Popular Physics
|
1303.4852
|
We show that optical second-harmonic generation (SHG) can be observed from
individual single-walled carbon nanotubes (SWCNTs) and, furthermore, allows
imaging of individual tubes. Detailed analysis of our results suggests that the
structural noncentrosymmetry, as required for SHG, arises from the non-zero
chiral angle of the SWCNT. SHG thus has potential as a fast, non-destructive,
and simple method for imaging of individual nanomolecules and for probing their
chiral properties. Even more, it opens the possibility to optically determine
the handedness of individual SWCNTs.
|
[
"cond-mat.mes-hall"
] |
cond-mat.mes-hall
|
Mesoscale and Nanoscale Physics
| 4,450Mesoscale and Nanoscale Physics
|
|
1905.03953
|
Alspach [{\sl Bull. Inst. Combin. Appl.}~{\bf 52} (2008), 7--20] defined the
maximal matching sequencibility of a graph $G$, denoted~$ms(G)$, to be the
largest integer $s$ for which there is an ordering of the edges of $G$ such
that every $s$ consecutive edges form a matching. In this paper, we consider
the natural analogue for hypergraphs of this and related results and determine
$ms(\lambda\mathcal{K}_{n_1,\ldots, n_k})$ where
$\lambda\mathcal{K}_{n_1,\ldots, n_k}$ denotes the multi-$k$-partite $k$-graph
with edge multiplicity $\lambda$ and parts of sizes $n_1,\ldots,n_k$,
respectively. It turns out that these invariants may be given surprisingly
precise and somewhat elegant descriptions, in a much more general setting.
|
[
"math.CO"
] |
math.CO
|
Combinatorics
| 1,014Combinatorics
|
|
1701.05896
|
T-branes, which are non-Abelian bound states of branes, were first introduced
by Cecotti, Cordova, Heckman and Vafa \cite{Cecotti:2010bp}. They are the
refined version of the monodromic branes that feature in the phenomenological
F-theory models. Here, we will be interested in the T-brane corresponding to
the $Z_3$ monodromy which is used to break the $E_8$ gauge group to obtain the
$SO(10)_{GUT}$. This extends the results of \cite{Cecotti:2010bp} to the case
of $Z_3$ monodromic T-branes used to break the $E_8$ gauge group to
$SO(10)\times SU(3)\times U(1)$ and compute the Yukawa coupling with the help
of the residue formula. We conclude that the Yukawa coupling,
${\bf{10}}_{H}\cdot {\bf{16}}_{M}\cdot {\bf{16}}_{M}$, is non-zero for $E_7$,
in complete agreement with \cite{Cecotti:2010bp}, but is zero for $E_8$.
Furthermore, the case of $Z_2$ monodromic T-branes used to break the $E_8$
gauge group to $E_{6}\times SU(2)\times U(1)$, nothing interesting can be
deduced by evaluating the Yukawa coupling ${\bf{27}}_{H}\cdot
{\bf{27}}_{M}\cdot {\bf{27}}_{M}$ which is dependent on whether the MSSM
fermion and electroweak Higgs fields can be included in the same ${\bf{27}}$
multiplet of a three-family $E_6$ GUT or assign the Higgs fields to a different
${\bf{27}}_{H}$ multiplet where only the Higgs doublets and singlets obtain the
electroweak scale energy.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
1901.07669
|
An array of spin torque oscillators (STOs) for practical applications such as
pattern recognition was recently proposed, where several STOs are connected by
a common nonmagnet. In this structure, in addition to the electric and/or
magnetic interactions proposed in previous works, the STOs are spontaneously
coupled to each other through the nonmagnetic connector, due to the injection
of spin current. Solving the Landau-Lifshitz-Gilbert equation numerically for
such system consisting of three STOs driven by the spin Hall effect, it is
found that both in-phase and antiphase synchronization of the STOs can be
achieved by adjusting the current density and appropriate distance between the
oscillators.
|
[
"cond-mat.mes-hall"
] |
cond-mat.mes-hall
|
Mesoscale and Nanoscale Physics
| 4,450Mesoscale and Nanoscale Physics
|
|
physics/9905061
|
Electron motion in an oblique shock wave is studied by means of a
one-dimensional, relativistic, electromagnetic, particle simulation code with
full ion and electron dynamics. It is found that an oblique shock can produce
electrons with ultra-relativistic energies; Lorentz factors with $\gamma \gto
100$ have been observed in our simulations. The physical mechanisms for the
reflection and acceleration are discussed, and the maximum energy is estimated.
If the electron reflection occurs near the end of a large-amplitude pulse,
those particles will then be trapped in the pulse and gain a great deal of
energy. The theory predicts that the electron energies can become especially
high at certain propagation angles. This is verified by the simulations.
|
[
"physics.plasm-ph",
"physics.space-ph"
] |
physics.plasm-ph
|
physics.space-ph
|
Plasma Physics;Space Physics
| 5,606Plasma Physics;Space Physics
|
0910.1355
|
We present a follow-up study of a series of papers concerning the role of
close interactions as a possible triggering mechanism of the activity of AGN
and starburst (SB) galaxies. We have already studied the close (<100 kpc) and
the large scale (<1 Mpc) environment of Sy1, Sy2 and Bright IRAS galaxies and
their respective control samples (Koulouridis et al.). The results led us to
the conclusion that a close encounter appears capable of activating a sequence
where a normal galaxy becomes first a starburst, then a Sy2 and finally a Sy1
galaxy. However since both galaxies of an interacting pair should be affected,
we present here optical spectroscopy and X-ray imaging of the neighbouring
galaxies around our Seyfert and BIRG galaxy samples. We find that more than 70%
of all neighbouring galaxies exhibit thermal or/and nuclear activity (namely
enhanced star formation, starbursting and/or AGN) and furthermore we discovered
various trends regarding the type and strength of the neighbour's activity with
respect to the activity of the central galaxy, the most important of which is
that the neighbours of Sy2 are systematically more ionized, and their straburst
is younger, than the neighbours of Sy1s. Our results not only strengthen the
link between close galaxy interactions and activity but also provide more clues
regarding the evolutionary sequence inferred by previous results.
|
[
"astro-ph.CO"
] |
astro-ph.CO
|
Cosmology and Nongalactic Astrophysics
| 1,725Cosmology and Nongalactic Astrophysics
|
|
2203.04244
|
Interfaces between dissimilar correlated oxides can offer devices with
versatile functionalities. In that respect, manipulating and measuring novel
physical properties of oxide heterointerfaces are highly desired. Yet, despite
extensive studies, obtaining direct information on their momentum-resolved
electronic structure remains a great challenge. This is because most correlated
interfacial phenomena appear within a few atomic layers from the interface,
thus limiting the application of available experimental probes. Here, we
utilize atomic-scale epitaxy and photoemission spectroscopy to demonstrate the
interface control of correlated electronic phases in atomic-scale
ruthenate--titanate heterostructures. While bulk SrRuO$_3$ is a ferromagnetic
metal, the heterointerfaces exclusively realize three distinct correlated
phases in the single-atomic-layer limit. Our theory reveals that atomic-scale
structural proximity effects lead to the emergence of Fermi liquid, Hund metal,
and Mott insulator phases in the quantum-confined SrRuO$_3$. These results
highlight the extensive interfacial tunability of electronic phases, hitherto
hidden in the atomically thin correlated heterostructure.
|
[
"cond-mat.str-el",
"cond-mat.mtrl-sci"
] |
cond-mat.str-el
|
cond-mat.mtrl-sci
|
Strongly Correlated Electrons;Materials Science
| 7,006Strongly Correlated Electrons;Materials Science
|
1107.3380
|
Given $d+1$ sets, or colours, $S_1, S_2,...,S_{d+1}$ of points in
$\mathbb{R}^d$, a {\em colourful} set is a set $S\subseteq\bigcup_i S_i$ such
that $|S\cap S_i|\leq 1$ for $i=1,...,d+1$. The convex hull of a colourful set
$S$ is called a {\em colourful simplex}. B\'ar\'any's colourful Carath\'eodory
theorem asserts that if the origin 0 is contained in the convex hull of $S_i$
for $i=1,...,d+1$, then there exists a colourful simplex containing 0. The
sufficient condition for the existence of a colourful simplex containing 0 was
generalized to 0 being contained in the convex hull of $S_i\cup S_j$ for $1\leq
i< j \leq d+1$ by Arocha et al. and by Holmsen et al. We further generalize the
sufficient condition and obtain new colourful Carath\'eodory theorems. We also
give an algorithm to find a colourful simplex containing 0 under the
generalized condition. In the plane an alternative, and more general, proof
using graphs is given. In addition, we observe that any condition implying the
existence of a colourful simplex containing 0 actually implies the existence of
$\min_i|S_i|$ such simplices.
|
[
"cs.CG",
"cs.DM",
"math.CO"
] |
cs.CG
|
cs.DM
|
Computational Geometry;Discrete Mathematics;Combinatorics
| 1,369Computational Geometry;Discrete Mathematics;Combinatorics
|
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