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arxiv_dataset-38001210.6206 | Results on Jet Spectra and Structure from ALICE
nucl-ex
Full jet reconstruction in ALICE uses the combined information from charged
and neutral particles. Essentially all jet constituents can be measured with
large efficiency down to very low transverse momenta (pT > 150 MeV/c). This has
the advantage to introduce a minimum bias on the jet fragmentation, in
particular for low jet momenta and in the presence of quenching. In this
article, we present preliminary results from reconstruction of charged jets in
Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV. The inclusive charged jet spectrum,
the jet nuclear modification factors (R_AA, R_CP), the ratio of spectra
measured with different resolution parameters and hadron-jet correlations are
discussed. For pp data at the same center of mass energy, the inclusive
spectrum of fully reconstructed jets and its resolution parameter dependence
are reported.
| arxiv topic:nucl-ex |
arxiv_dataset-38011210.6306 | Adiabatic piston in a temperature gradient
cond-mat.stat-mech
The steady states of two gases of hard spheres or disks separated by an
adiabatic piston in presence of a temperature gradient are discussed. The
temperature field is generated by two thermal walls at different temperatures,
each of them in contact with one of the gases. The presence of the piston
strongly affects the hydrodynamic fields, inducing a jump in its vicinity. A
simple kinetic theory model is formulated. Its predictions are shown to be in
good agreement with molecular dynamics simulation results. The applicability of
the minimum entropy production principle is analyzed, and it is found that it
only provides an accurate description of the system in the limit of a small
temperature gradient.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-38021210.6406 | Strongly Stable Automorphisms of the Categories of the Finitely
Generated Free Algebras of the some Varieties of Linear Algebras
math.RA
In this paper we consider some classical varieties of linear algebras over
the field which has characteristic 0. For every considered variety we take a
category of the finite generated free algebras of this variety. And for every
this category we calculate the quotient group of the group of the all
automorphisms of this category over the subgroup of the all inner
automorphisms. This quotient group measures difference between the geometric
equivalence and automorphic equivalence of algebras from this variety.
| arxiv topic:math.RA |
arxiv_dataset-38031210.6506 | Metric-enriched categories and approximate Fra\"{i}ss\'{e} limits
math.CT math.FA math.GN
We develop the theory of approximate Fra\"{i}ss\'{e} limits in the context of
categories enriched over metric spaces. Among applications, we construct a
generic projection on the Gurarii space and we present a simpler proof of a
characterization of the pseudo-arc, due to Irwin and Solecki.
| arxiv topic:math.CT math.FA math.GN |
arxiv_dataset-38041210.6606 | On the magnetic field required for driving the observed angular-velocity
variations in the solar convection zone
astro-ph.SR
A putative temporally varying circulation-free magnetic-field configuration
is inferred in an equatorial segment of the solar convection zone from the
helioseismologically inferred angular-velocity variation, assuming that the
predominant dynamics is angular acceleration produced by the azimuthal Maxwell
stress exerted by a field whose surface values are consistent with photospheric
line-of-sight measurements.
| arxiv topic:astro-ph.SR |
arxiv_dataset-38051210.6706 | Quantifying properties of ICM inhomogeneities
astro-ph.HE astro-ph.CO
We present a new method to identify and characterize the structure of the
intracluster medium (ICM) in simulated galaxy clusters. The method uses the
median of gas properties, such as density and pressure, which we show to be
very robust to the presence of gas inhomogeneities. In particular, we show that
the radial profiles of median gas properties are smooth and do not exhibit
fluctuations at locations of massive clumps in contrast to mean and mode
properties. It is shown that distribution of gas properties in a given radial
shell can be well described by a log-normal PDF and a tail. The former
corresponds to a nearly hydrostatic bulk component, accounting for ~99% of the
volume, while the tail corresponds to high density inhomogeneities. We show
that this results in a simple and robust separation of the diffuse and clumpy
components of the ICM. The FWHM of the density distribution grows with radius
and varies from ~0.15 dex in cluster centre to ~0.5 dex at 2r_500 in relaxed
clusters. The small scatter in the width between relaxed clusters suggests that
the degree of inhomogeneity is a robust characteristic of the ICM. It broadly
agrees with the amplitude of density perturbations in the Coma cluster. We
discuss the origin of ICM density variations in spherical shells and show that
less than 20% of the width can be attributed to the triaxiality of the cluster
gravitational potential. As a link to X-ray observations of real clusters we
evaluated the ICM clumping factor with and without high density
inhomogeneities. We argue that these two cases represent upper and lower limits
on the departure of the observed X-ray emissivity from the median value. We
find that the typical value of the clumping factor in the bulk component of
relaxed clusters varies from ~1.1-1.2 at r_500 up to ~1.3-1.4 at r_200, in
broad agreement with recent observations.
| arxiv topic:astro-ph.HE astro-ph.CO |
arxiv_dataset-38061210.6806 | SQUIDs based set-up for probing current noise and correlations in
three-terminal devices
cond-mat.mes-hall
We have implemented a new experimental set-up for precise measurements of
current fluctuations in three-terminal devices. The system operates at very low
temperatures (30 mK) and is equipped with three SQUIDs as low noise current
amplifiers. A SQUID input coil is connected to each terminal of a sample
allowing the acquisition of time-dependent current everywhere in the circuit.
From these traces, we can measure the current mean value, the noise and
cross-correlations between different branches of a device. In this paper we
present calibration results of noise and cross-correlations obtained using low
impedance macroscopic resistors. From these results we can extract the noise
level of the set-up and show that there are no intrinsic correlations due to
the measurement scheme. We also studied noise and correlations as a function of
a DC current and estimated the electronic temperature of various macroscopic
resistors.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-38071210.6906 | Coherence expansion and polariton condensate formation in a
semiconductor microcavity
cond-mat.mes-hall
The dynamics of the expansion of the first order spatial coherence g(1) for a
polariton system in a high-Q GaAs microcavity was investigated on the basis of
Young's double slit experiment under 3 ps pulse excitation at the conditions of
polariton Bose-Einstein condensation. It was found that in the process of
condensate formation the coherence expands with a constant velocity of about
10^8 cm/s. The measured coherence is smaller than that in thermally equilibrium
system during the growth of condensate density and well exceeds it at the end
of condensate decay. The onset of spatial coherence is governed by polariton
relaxation while condensate amplitude and phase fluctuations are not
suppressed.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-38081210.7006 | A Multi-Criteria Framework with Voxel-Dependent Parameters for
Radiotherapy Treatment Plan Optimization
physics.med-ph
In a treatment plan optimization problem for radiotherapy, a clinically
acceptable plan is usually generated by an optimization process with weighting
factors or reference doses adjusted for organs. Recent discoveries indicate
that adjusting parameters associated with each voxel may lead to better plan
quality. However, it is still unclear regarding the mathematical reasons behind
it. To answer questions related to this problem, we establish in this work a
new mathematical framework equipped with two theorems. The new framework
clarifies the different consequences of adjusting organ-dependent and
voxel-dependent parameters for the treatment plan optimization of radiation
therapy, as well as the different effects of adjusting weighting factors versus
reference doses in the optimization process. The main discoveries are
threefold: 1) While in the organ-based model the selection of the objective
function has an impact on the quality of the optimized plans, this is no longer
an issue for the voxel-based model since the entire Pareto surface could be
generated regardless the specific form of the objective function as long as it
satisfies certain mathematical conditions; 2) A larger Pareto surface is
explored by adjusting voxel-dependent parameters than by adjusting
organ-dependent parameters, possibly allowing for the generation of plans with
better trade-offs among different clinical objectives; 3) Adjusting voxel
weighting factors is preferred to adjusting the voxel reference doses since the
Pareto optimality can be maintained.
| arxiv topic:physics.med-ph |
arxiv_dataset-38091210.7106 | Spatially Resolved Observations of the Bipolar Optical Outflow from the
Brown Dwarf 2MASSJ12073347-3932540
astro-ph.SR
Studies of brown dwarf (BD) outflows provide information pertinent to
questions on BD formation, as well as allowing outflow mechanisms to be
investigated at the lowest masses. Here new observations of the bipolar outflow
from the 24 M$_{JUP}$ BD, 2MASSJ12073347-3932540 are presented. The outflow was
originally identified through the spectro-astrometric analysis of the
[OI]$\lambda$6300 emission line. Follow-up observations consisting of spectra
and [SII], R-band and I-band images were obtained. The new spectra confirm the
original results and are used to constrain the outflow PA at $\sim$
65$^{\circ}$. The [OI]$\lambda$6300 emission line region is spatially resolved
and the outflow is detected in the [SII] images. The detection is firstly in
the form of an elongation of the point spread function along the direction of
the outflow PA. Four faint knot-like features (labelled {\it A-D}) are also
observed to the south-west of 2MASSJ12073347-3932540 along the same PA
suggested by the spectra and the elongation in the PSF. Interestingly, {\it D},
the feature furthest from the source is bow-shaped with the apex pointing away
from 2MASSJ12073347-3932540. A color-color analysis allows us to conclude that
at least feature {\it D} is part of the outflow under investigation while {\it
A} is likely a star or galaxy. Follow-up observations are needed to confirm the
origin of {\it B} and {\it C}. This is a first for a BD, as BD optical outflows
have to date only been detected using spectro-astrometry. This result also
demonstrates for the first time that BD outflows can be collimated and
episodic.
| arxiv topic:astro-ph.SR |
arxiv_dataset-38101210.7206 | Baseline study for higher moments of net-charge distribution at RHIC
energies
nucl-ex hep-ex hep-ph
Lattice QCD models predict the presence of a critical point in the QCD phase
diagram where the first order phase transition between the hadron gas and
Quark-Gluon Plasma ceases to exist. Higher moments of conserved quantities,
such as net-charge, net-baryon number and net-strangeness, are proposed to be
sensitive probes for locating the critical point. The moments of net-charge
distributions have been studied as a function of centrality for {Au+Au}
collisions at $\sqrt{s_{\rm NN}}$ = 7.7 to 200 GeV using three event
generators, {\it viz.}, UrQMD, HIJING, and THERMINATOR-2. The effect of
centrality selection, resonance production, as well as contributions from
particle species to the net-charge moments and their products have been
studied. It is observed that mean of the net-charge distributions are dominated
by net-protons, whereas standard deviation, skewness and kurtosis closely
follow net-pion distributions. These results, along with the predictions from
Hadron Resonance Gas (HRG) model, are presented.
| arxiv topic:nucl-ex hep-ex hep-ph |
arxiv_dataset-38111210.7306 | Cosmology constrains gravitational four-fermion interaction
astro-ph.CO gr-qc
If torsion exists, it generates gravitational four-fermion interaction
(GFFI). This interaction gets dominating on the Planck scale. If one confines
to the regular, axial-axial part of this interaction, the results do not comply
with the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology for the spatial
flat or closed Universe. In principle, the anomalous, vector-vector interaction
could restore the agreement.
| arxiv topic:astro-ph.CO gr-qc |
arxiv_dataset-38121210.7406 | Wannier-Stark states and Bloch oscillations in the honeycomb lattice
cond-mat.str-el quant-ph
We study a quantum particle in a tilted honeycomb lattice in the
tight-binding approximation. First we discuss the particle eigenstates, i.e.,
the stationary Wannier-Stark states. These states are proved to be extended
states for the rational directions of the static field and localized states for
the irrational directions. We find energy bands of the extended states and
analyze the localized states. It is shown, in particular, that the localized
`honeycomb' Wannier-Stark states are chaotic states with irregular dependence
of the localization length on the static field magnitude. Second we discuss
Bloch oscillations of the quantum particle. Irregular Bloch oscillations for
irrational directions are observed.
| arxiv topic:cond-mat.str-el quant-ph |
arxiv_dataset-38131210.7506 | Convolutional Compressed Sensing Using Deterministic Sequences
cs.IT cs.MM math.IT
In this paper, a new class of circulant matrices built from deterministic
sequences is proposed for convolution-based compressed sensing (CS). In
contrast to random convolution, the coefficients of the underlying filter are
given by the discrete Fourier transform of a deterministic sequence with good
autocorrelation. Both uniform recovery and non-uniform recovery of sparse
signals are investigated, based on the coherence parameter of the proposed
sensing matrices. Many examples of the sequences are investigated, particularly
the Frank-Zadoff-Chu (FZC) sequence, the \textit{m}-sequence and the Golay
sequence. A salient feature of the proposed sensing matrices is that they can
not only handle sparse signals in the time domain, but also those in the
frequency and/or or discrete-cosine transform (DCT) domain.
| arxiv topic:cs.IT cs.MM math.IT |
arxiv_dataset-38141210.7606 | On Lower Bounds of the First Eigenvalue of Finsler-Laplacian
math.DG math.AP
By using Bochner technique and gradient estimate, we give the lower bound
estimates of the first eigenvalue of Finsler-Laplacian on Finsler manifolds.
These results generalize the corresponding famous theorems in the Riemannian
geometry.
| arxiv topic:math.DG math.AP |
arxiv_dataset-38151210.7706 | The Effect of Density on the Thermal Structure of
Gravitationally-Darkened Be Star Disks
astro-ph.SR
The effects of gravitational darkening on the thermal structure of Be star
disks of differing densities are systematically examined. Gravitational
darkening is the decrease of the effective temperature near the equator and the
corresponding increase near the poles of a star caused by rapid rotation. We
also include the rotational distortion of the star using the Roche Model.
Increasing the disk density increases the optical depths in the equatorial
plane, resulting in the formation of an inner cool region near the equatorial
plane of the disk. High rotation rates result in disks that have temperatures
similar to those of a denser disk, namely cooler overall. However the effect of
increasing rotation produces additional heating in the upper disk due to the
hotter stellar pole. Cool regions in the equatorial plane normally associated
with high density are seen in low density models at high rotation rates.
Gravitational darkening increases the amount of very cool and very hot material
in the disk and decreases the amount of disk material at moderate temperatures.
We also present models which study the effect of gravitational darkening on
hydrostatically-converged disks, in which the temperature structure is
consistent with vertical hydrostatic equilibrium. Because the equatorial
regions become cooler, hydrostatically converged models that include gravity
darkening have smaller vertical scale heights, and $H/R$ is smaller by as much
as 56% near $v_{\rm crit}$. Finally we explore differences in disk temperatures
when alternate formulations of gravitational darkening, which lower the
temperature difference between the pole and the equator, are used.
| arxiv topic:astro-ph.SR |
arxiv_dataset-38161210.7806 | MSSM: Cornered and Correlated
hep-ph hep-ex
Inspired by the latest results of ATLAS and CMS on the search for the
standard model (SM) Higgs scalar, we discuss in this article the correlations
between Higgs-boson properties, low-energy observables, such as B -> X_sgamma,
B_s -> mu^+mu^-, and (g-2)_mu, and the dark matter (DM) relic density. We focus
on the corners of the MSSM parameter space where the pp -> h -> gammagamma
signal is enhanced due to the presence of a light stau state. In this region
tan(beta), M_A, A_t, and mu take large values, and we find striking
correlations between many of the considered observables. In particular, the B
-> X_sgamma branching fraction is enhanced, while the B_s -> mu^+mu^- rate
tends to be below the SM expectation. In contrast, the Higgs-boson couplings
show good overall agreement with the preliminary experimental determinations,
the DM abundance is consistent with observation, and the discrepancy in
(g-2)_mu is reduced. The predicted deviations and found correlations could be
tested in the near future and hence may become very valuable as guidelines and
consistency checks.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-38171210.7906 | Synthesis-by-analysis of BCH Codes
cs.IT math.IT
In this paper we propose a technique to blindly synthesize the generator
polynomial of BCH codes. The proposed technique involves finding Greatest
Common Divisor (GCD) among different codewords and block lengths. Based on this
combinatorial GCD calculation, correlation values are found. For a valid block
length, the iterative GCD calculation results either into generator polynomial
or some of its higher order multiples. These higher order polynomials are
factorized under modulo-2 operation, and one of the resulting factors is always
the generator polynomial which further increases the correlation value. The
resulting correlation plot for different polynomials shows very high values for
correct block length and valid generator polynomial. Knowing the valid block
length and generator polynomial, all other parameters including number of
parity-check digits (n-k), minimum distance dmin and error correcting
capability t are readily exposed.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-38181210.8006 | Three-dimensional isolated quotient singularities in odd characteristic
math.AG math.AC
Let a finite group G act linearly on a finite dimensional vector space V over
an algebraically closed field k of characteristic p>2. Assume that the quotient
V/G is an isolated singularity. In the case when p does not divide the order of
G, isolated singularities V/G are completely classified and their
classification reduces to Zassenhaus-Vincent-Wolf classification of isolated
quotient singularities over the field of complex numbers. In the present paper
we show that if dimension of V is 3, then also in the modular case (p divides
the order of G) classification of isolated quotient singularities reduces to
Zassenhaus-Vincent-Wolf classification. Some remarks on modular quotient
singularities in other dimensions and in even characteristic are also given.
| arxiv topic:math.AG math.AC |
arxiv_dataset-38191210.8106 | Late Time Acceleration of the 3-Space in a Higher Dimensional Steady
State Universe in Dilaton Gravity
gr-qc astro-ph.CO
We present cosmological solutions for (1+3+n)-dimensional steady state
universe in dilaton gravity with an arbitrary dilaton coupling constant w and
exponential dilaton self-interaction potentials in the string frame. We focus
particularly on the class in which the 3-space expands with a time varying
deceleration parameter. We discuss the number of the internal dimensions and
the value of the dilaton coupling constant to determine the cases that are
consistent with the observed universe and the primordial nucleosynthesis. The
3-space starts with a decelerated expansion rate and evolves into accelerated
expansion phase subject to the values of w and n, but ends with a Big Rip in
all cases. We discuss the cosmological evolution in further detail for the
cases w=1 and w=1/2 that permit exact solutions. We also comment on how the
universe would be conceived by an observer in four dimensions who is unaware of
the internal dimensions and thinks that the conventional general relativity is
valid at cosmological scales.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-38201210.8206 | Tiling branching multiplicity spaces with GL2 pattern blocks
math.RT
We study branching multiplicity spaces of complex classical groups in terms
of GL(2) representations. In particular, we show how combinatorics of GL(2)
representations are intertwined to make branching rules under the restriction
of GL(n) to GL(n-2). We also discuss analogous results for the symplectic and
orthogonal groups.
| arxiv topic:math.RT |
arxiv_dataset-38211210.8306 | Fourth-order perturbative equations in Lagrangian perturbation theory
for a cosmological dust fluid
astro-ph.CO
We have derived fourth-order perturbative equations in Lagrangian
perturbation theory for a cosmological dust fluid. These equations are derived
under the supposition of Newtonian cosmology in the
Friedmann-Lema\^{i}tre-Robertson-Walker Universe model. Even if we consider the
longitudinal mode in the first-order perturbation, the transverse mode appears
in the third-order perturbation. Furthermore, in this case, six
longitudinal-mode equations and four transverse-mode equations appear in the
fourth-order perturbation. The application of the fourth-order perturbation
leads to a precise prediction of the large-scale structure.
| arxiv topic:astro-ph.CO |
arxiv_dataset-38221210.8406 | Neutral stability, rate propagation, and critical branching in
feedforward networks
q-bio.NC
Recent experimental and computational evidence suggests that several
dynamical properties may characterize the operating point of functioning neural
networks: critical branching, neutral stability, and production of a wide range
of firing patterns. We seek the simplest setting in which these properties
emerge, clarifying their origin and relationship in random, feedforward
networks of McCullochs-Pitts neurons. Two key parameters are the thresholds at
which neurons fire spikes, and the overall level of feedforward connectivity.
When neurons have low thresholds, we show that there is always a connectivity
for which the properties in question all occur: that is, these networks
preserve overall firing rates from layer to layer and produce broad
distributions of activity in each layer. This fails to occur, however, when
neurons have high thresholds. A key tool in explaining this difference is
eigenstructure of the resulting mean-field Markov chain, as this reveals which
activity modes will be preserved from layer to layer. We extend our analysis
from purely excitatory networks to more complex models that include inhibition
and 'local' noise, and find that both of these features extend the parameter
ranges over which networks produce the properties of interest.
| arxiv topic:q-bio.NC |
arxiv_dataset-38231211.0054 | Applications of the Defect of a Finitely Presented Functor
math.CT math.RT
For an abelian category $\mathcal{A}$, the defect sequence $$0\longrightarrow
F_0\longrightarrow F\overset{\varphi}{\longrightarrow}
\big(w(F),\hspace{0.05cm}\underline{\ \ }\hspace{0.1cm} \big)\longrightarrow
F_1\longrightarrow 0$$ of a finitely presented functor is used to establish the
CoYoneda Lemma. An application of this result is the $\textsf{fp}$-dual formula
which states that for any covariant finitely presented functor $F$, $F^*\cong
\big(\hspace{0.05cm}\underline{\ \ }\hspace{0.1cm} , w(F)\big)$. The defect
sequence is shown to be isomorphic to both the double dual sequence
$$0\longrightarrow \textsf{Ext}^1(\textsf{Tr} F,\textsf{Hom})\longrightarrow
F\longrightarrow F^{**}\longrightarrow \textsf{Ext}^2(\textsf{Tr}
F,\textsf{Hom})\longrightarrow 0$$ and the injective stabilization sequence
$$0\longrightarrow \overline{F}\longrightarrow F\longrightarrow
R^0F\longrightarrow \tilde F\longrightarrow 0$$ establishing the
$\textsf{fp}$-injective stabilization formula $\overline{F}\cong
\textsf{Ext}^1(\textsf{Tr} F,\textsf{Hom})$ for any finitely presented functor
$F$. The injectives of $\textsf{fp}(\textsf{Mod}(R),\textsf{Ab})$ are used to
compute the left derived functors $L^k(\hspace{0.05cm}\underline{\ \
}\hspace{0.1cm} )^*$. These functors are shown to detect certain short exact
sequences.
| arxiv topic:math.CT math.RT |
arxiv_dataset-38241211.0154 | Dynamics of Dark Matter in Baryon-Radiation Plasma: Perspectives using
Meschersky equation
astro-ph.CO gr-qc
With an aim to argue for the truly collisionless nature of cold dark matter
between epochs of equality and recombination, we assume a model, wherein
strongly coupled baryon-radiation plasma ejects out of small regions of
concentrated cold dark matter without losing its equilibrium. We use the
Meschersky equation to describe the dynamics of cold dark matter in the
presence of varying mass of strongly coupled baryon-radiation plasma. Based on
this model, we discuss the growth of perturbations in cold dark matter both in
the Jeans theory and in the expanding universe using Newton's theory. We see
the effect of the perturbations in the cold dark matter potential on the cosmic
microwave background anisotropy that originated at redshifts between equality
and recombination i.e. $1100 < z < z_{eq}$. Also we obtain an expression for
the Sachs-Wolfe effect, i.e. the CMB temperature anisotropy at decoupling in
terms of the perturbations in cold dark matter potential. We obtain similar
solutions both in the static and in the expanding universe, for epochs of
recombination. From this, we infer about the time scale when the dark energy
starts to dominate.
| arxiv topic:astro-ph.CO gr-qc |
arxiv_dataset-38251211.0254 | Improving VERITAS Sensitivity by Fitting 2D Gaussian Image Parameters
astro-ph.IM
Our goal is to improve the acceptance and angular resolution of VERITAS by
implementing a camera image-fitting algorithm. Elliptical image parameters are
extracted from 2D Gaussian distribution fits using a (chi)^2 minimization
instead of the standard technique based on the principle moments of an island
of pixels above threshold. We optimize the analysis cuts and then characterize
the improvements using simulations. We find an improvement of 20% less
observing time to reach 5-sigma for weak point sources.
| arxiv topic:astro-ph.IM |
arxiv_dataset-38261211.0354 | Isotopic Equivalence from Bezier Curve Subdivision
math.GT
We prove that the control polygon of a Bezier curve B becomes homeomorphic
and ambient isotopic to B via subdivision, and we provide closed-form formulas
to compute the number of iterations to ensure these topological
characteristics. We first show that the exterior angles of control polygons
converge exponentially to zero under subdivision.
| arxiv topic:math.GT |
arxiv_dataset-38271211.0454 | Local dimensions for the random beta-transformation
math.DS
The random beta-transformation K is isomorphic to a full shift. This relation
gives an invariant measure for K that yields the Bernoulli convolution by
projection. We study the local dimension of the invariant measure for K for
special values of beta and use the projection to obtain results on the local
dimension of the Bernoulli convolution.
| arxiv topic:math.DS |
arxiv_dataset-38281211.0554 | A paucity of proto-hot Jupiters on super-eccentric orbits
astro-ph.EP
Gas giant planets orbiting within 0.1 AU of their host stars, unlikely to
have formed in situ, are evidence for planetary migration. It is debated
whether the typical hot Jupiter smoothly migrated inward from its formation
location through the proto-planetary disk or was perturbed by another body onto
a highly eccentric orbit, which tidal dissipation subsequently shrank and
circularized during close stellar passages. Socrates and collaborators
predicted that the latter class of model should produce a population of
super-eccentric proto-hot Jupiters readily observable by Kepler. We find a
paucity of such planets in the Kepler sample, inconsistent with the theoretical
prediction with 96.9% confidence. Observational effects are unlikely to explain
this discrepancy. We find that the fraction of hot Jupiters with orbital period
P > 3 days produced by the star-planet Kozai mechanism does not exceed (at
two-sigma) 44%. Our results may indicate that disk migration is the dominant
channel for producing hot Jupiters with P > 3 days. Alternatively, the typical
hot Jupiter may have been perturbed to a high eccentricity by interactions with
a planetary rather than stellar companion and began tidal circularization much
interior to 1 AU after multiple scatterings. A final alternative is that tidal
circularization occurs much more rapidly early in the tidal circularization
process at high eccentricities than later in the process at low eccentricities,
contrary to current tidal theories.
| arxiv topic:astro-ph.EP |
arxiv_dataset-38291211.0654 | On Threshold Models over Finite Networks
cs.DM cs.GT cs.SI
We study a model for cascade effects over finite networks based on a
deterministic binary linear threshold model. Our starting point is a networked
coordination game where each agent's payoff is the sum of the payoffs coming
from pairwise interactions with each of the neighbors. We first establish that
the best response dynamics in this networked game is equivalent to the linear
threshold dynamics with heterogeneous thresholds over the agents. While the
previous literature has studied such linear threshold models under the
assumption that each agent may change actions at most once, a study of best
response dynamics in such networked games necessitates an analysis that allows
for multiple switches in actions. In this paper, we develop such an analysis
and construct a combinatorial framework to understand the behavior of the
model. To this end, we establish that the agents behavior cycles among
different actions in the limit and provide three sets of results.
We first characterize the limiting behavioral properties of the dynamics. We
determine the length of the limit cycles and reveal bounds on the time steps
required to reach such cycles for different network structures. We then study
the complexity of decision/counting problems that arise within the context.
Specifically, we consider the tractability of counting the number of limit
cycles and fixed-points, and deciding the reachability of action profiles. We
finally propose a measure of network resilience that captures the nature of the
involved dynamics. We prove bounds and investigate the resilience of different
network structures under this measure.
| arxiv topic:cs.DM cs.GT cs.SI |
arxiv_dataset-38301211.0754 | Coding of nonlinear states for the Gross-Pitaevskii equation with
periodic potential
nlin.PS cond-mat.quant-gas math-ph math.MP nlin.CD
We study nonlinear states for NLS-type equation with additional periodic
potential U(x) (called the Gross-Pitaevskii equation, GPE, in theory of
Bose-Einstein Condensate, (BEC)). We prove that if the nonlinearity is
defocusing (repulsive, in BEC context) then under certain conditions there
exists a homeomorphism between the set of nonlinear states for GPE (i.e. real
bounded solutions of some nonlinear ODE) and the set of bi-infinite sequences
of numbers from 1 to N for some integer N. These sequences can be viewed as
codes of the nonlinear states. Sufficient conditions for the homeomorphism to
exist are given in the form of three hypotheses. For a given U(x), the
verification of the hypotheses should be done numerically. We report on
numerical results for the case of GPE with cosine potential and describe
regions in the plane of parameters where this coding is possible.
| arxiv topic:nlin.PS cond-mat.quant-gas math-ph math.MP nlin.CD |
arxiv_dataset-38311211.0854 | Twelve type II-P supernovae seen with the eyes of Spitzer
astro-ph.SR
Core-collapse supernovae (CC SNe), especially those of type II-plateau
(II-P), are thought to be important contributors to cosmic dust production. The
most obvious indicator of the presence of newly-formed and/or pre-existing dust
is the time-dependent mid-infrared (MIR) excess coming from the environment of
SNe. Our goal was to collect publicly available, previously unpublished
measurements on type II-P (or peculiar IIP) SNe from the Spitzer database. The
temporal changes of the observed fluxes may be indicative of the underlying
supernova, while spectral energy distribution (SED) fitting to the fluxes in
different IRAC channels may reveal the physical parameters of the mid-IR
radiation, presumably due to warm dust. IRS spectra were extracted and
calibrated with SPICE, while photometric SEDs were assembled using IRAF and
MOPEX. Calculated SEDs from observed fluxes were fit with simple dust models to
get basic information on the dust presumed as the source of MIR radiation. We
found twelve SNe satisfying the criterion above, observed at late-time epochs
(typically after +300 days). In three cases we could not identify any point
source at the SN position on late time IRAC images. We found two SNe, 2005ad
and 2005af, which likely have newly-formed dust in their environment, while in
the other seven cases the observed MIR flux may originate from pre-existing
circumstellar or interstellar dust. Our results support the previous
observational conclusions that warm new dust in the environment of SNe
contributes only marginally to cosmic dust content.
| arxiv topic:astro-ph.SR |
arxiv_dataset-38321211.0954 | Jointly Optimal Sensing and Resource Allocation for Multiuser Overlay
Cognitive Radios
cs.NI cs.IT cs.SY math.IT
Successful deployment of cognitive radios requires efficient sensing of the
spectrum and dynamic adaptation of the available resources according to the
sensed (imperfect) information. While most works design these two tasks
separately, in this paper we address them jointly. In particular, we
investigate an overlay cognitive radio with multiple secondary users that
access orthogonally a set of frequency bands originally devoted to primary
users. The schemes are designed to minimize the cost of sensing, maximize the
performance of the secondary users (weighted sum rate), and limit the
probability of interfering the primary users. The joint design is addressed
using dynamic programming and nonlinear optimization techniques. A two-step
strategy that first finds the optimal resource allocation for any sensing
scheme and then uses that solution as input to solve for the optimal sensing
policy is implemented. The two-step strategy is optimal, gives rise to
intuitive optimal policies, and entails a computational complexity much lower
than that required to solve the original formulation.
| arxiv topic:cs.NI cs.IT cs.SY math.IT |
arxiv_dataset-38331211.1054 | The Calderon problem with partial data on manifolds and applications
math.AP math.DG
We consider Calderon's inverse problem with partial data in dimensions $n
\geq 3$. If the inaccessible part of the boundary satisfies a (conformal)
flatness condition in one direction, we show that this problem reduces to the
invertibility of a broken geodesic ray transform. In Euclidean space, sets
satisfying the flatness condition include parts of cylindrical sets, conical
sets, and surfaces of revolution. We prove local uniqueness in the Calderon
problem with partial data in admissible geometries, and global uniqueness under
an additional concavity assumption. This work unifies two earlier approaches to
this problem (\cite{KSU} and \cite{I}) and extends both. The proofs are based
on improved Carleman estimates with boundary terms, complex geometrical optics
solutions involving reflected Gaussian beam quasimodes, and invertibility of
(broken) geodesic ray transforms. This last topic raises questions of
independent interest in integral geometry.
| arxiv topic:math.AP math.DG |
arxiv_dataset-38341211.1154 | The validation of (advanced) bibliometric indicators through peer
assessments: A comparative study using data from InCites and F1000
cs.DL stat.AP
The data of F1000 provide us with the unique opportunity to investigate the
relationship between peers' ratings and bibliometric metrics on a broad and
comprehensive data set with high-quality ratings. F1000 is a post-publication
peer review system of the biomedical literature. The comparison of metrics with
peer evaluation has been widely acknowledged as a way of validating metrics.
Based on the seven indicators offered by InCites, we analyzed the validity of
raw citation counts (Times Cited, 2nd Generation Citations, and 2nd Generation
Citations per Citing Document), normalized indicators (Journal Actual/Expected
Citations, Category Actual/Expected Citations, and Percentile in Subject Area),
and a journal based indicator (Journal Impact Factor). The data set consists of
125 papers published in 2008 and belonging to the subject category cell biology
or immunology. As the results show, Percentile in Subject Area achieves the
highest correlation with F1000 ratings; we can assert that for further three
other indicators (Times Cited, 2nd Generation Citations, and Category
Actual/Expected Citations) the 'true' correlation with the ratings reaches at
least a medium effect size.
| arxiv topic:cs.DL stat.AP |
arxiv_dataset-38351211.1254 | Towards Rapid Parameter Estimation on Gravitational Waves from Compact
Binaries using Interpolated Waveforms
astro-ph.HE astro-ph.IM gr-qc
Accurate parameter estimation of gravitational waves from coalescing compact
binary sources is a key requirement for gravitational-wave astronomy.
Evaluating the posterior probability density function of the binary's
parameters (component masses, sky location, distance, etc.) requires computing
millions of waveforms. The computational expense of parameter estimation is
dominated by waveform generation and scales linearly with the waveform
computational cost. Previous work showed that gravitational waveforms from
non-spinning compact binary sources are amenable to a truncated singular value
decomposition, which allows them to be reconstructed via interpolation at fixed
computational cost. However, the accuracy requirement for parameter estimation
is typically higher than for searches, so it is crucial to ascertain that
interpolation does not lead to significant errors. Here we provide a proof of
principle to show that interpolated waveforms can be used to recover posterior
probability density functions with negligible loss in accuracy with respect to
non-interpolated waveforms. This technique has the potential to significantly
increase the efficiency of parameter estimation.
| arxiv topic:astro-ph.HE astro-ph.IM gr-qc |
arxiv_dataset-38361211.1354 | An Extension of the Quantum Theory of Cosmological Perturbations to the
Planck Era
gr-qc astro-ph.CO hep-th math-ph math.MP
Cosmological perturbations are generally described by quantum fields on
(curved but) classical space-times. While this strategy has a large domain of
validity, it can not be justified in the quantum gravity era where curvature
and matter densities are of Planck scale. Using techniques from loop quantum
gravity, the standard theory of cosmological perturbations is extended to
overcome this limitation. The new framework sharpens conceptual issues by
distinguishing between the true and apparent trans-Planckian difficulties and
provides sufficient conditions under which the true difficulties can be
overcome within a quantum gravity theory. In a companion paper, this framework
is applied to the standard inflationary model, with interesting implications to
theory as well as observations.
| arxiv topic:gr-qc astro-ph.CO hep-th math-ph math.MP |
arxiv_dataset-38371211.1454 | A Novel String Field Theory Solving String Theory by Liberating Left and
Right Mover
hep-th
We put forward ideas to a novel string field theory based on making some
"objects" that essentially describe "liberated" left- and right- mover fields
$X^{\mu}_{L}(\tau + \sigma)$ and $X^{\mu}_{R}(\tau - \sigma)$ on the string.
The main progress is that we manage to make our novel string field theory
provide the correct mass square spectrum for the string. An interesting detail
is that we have to dispense of a species doubler caused by the discretization
we introduced in our string field theory of the string right- and left- mover
variables. We finally suggest how to obtain the Veneziano amplitude in our
model.
| arxiv topic:hep-th |
arxiv_dataset-38381211.1554 | Semiclassical equivalence of Green-Schwarz and Pure-Spinor/Hybrid
formulations of superstrings in AdS(5) x S(5) and AdS(2) x S(2) x T(6)
hep-th
We demonstrate the equivalence between the worldsheet one-loop partition
functions computed near classical string solutions in the Green-Schwarz and in
the pure-spinor formulations of superstrings in AdS(5) x S(5). While their
bosonic sectors are the same in the conformal gauge, their fermionic sectors
superficially appear to be very different (first vs second derivative kinetic
terms, presence vs absence of fermionic gauge symmetry). Still, we show that
the quadratic fluctuation spectrum of sixteen fermionic modes of the
pure-spinor formulation is the same as in the Green-Schwarz superstring and the
contribution of the extra "massless" fermionic modes cancels against that of
the pure-spinor ghosts. We also provide evidence for a similar semiclassical
equivalence between the Green-Schwarz and the hybrid formulations of
superstrings in AdS(2) x S(2) x T(6) by studying several particular examples of
string solutions.
| arxiv topic:hep-th |
arxiv_dataset-38391211.1654 | A New Randomness Evaluation Method with Applications to Image Shuffling
and Encryption
cs.CR cs.CV stat.AP
This letter discusses the problem of testing the degree of randomness within
an image, particularly for a shuffled or encrypted image. Its key contributions
are: 1) a mathematical model of perfectly shuffled images; 2) the derivation of
the theoretical distribution of pixel differences; 3) a new $Z$-test based
approach to differentiate whether or not a test image is perfectly shuffled;
and 4) a randomized algorithm to unbiasedly evaluate the degree of randomness
within a given image. Simulation results show that the proposed method is
robust and effective in evaluating the degree of randomness within an image,
and may often be more suitable for image applications than commonly used
testing schemes designed for binary data like NIST 800-22. The developed method
may be also useful as a first step in determining whether or not a shuffling or
encryption scheme is suitable for a particular cryptographic application.
| arxiv topic:cs.CR cs.CV stat.AP |
arxiv_dataset-38401211.1754 | The idempotents in cyclotomic Hecke algebras and periodic property of
the Jucys-Murphy elements
math.RT
This paper proves a periodic property of Jucys-Murphy elements of the
degenerate and non-degenerate cy- clotomic Hecke algebras of type A. We do this
by first giving a new closed formula for the KLR idempotents e(i) which, it
tuns out, is very efficient computationally.
| arxiv topic:math.RT |
arxiv_dataset-38411211.1854 | Half-page derivation of the Thomas precession
physics.class-ph gr-qc quant-ph
Instantaneous derivation of the Thomas precession with only basic vector
calculus.
| arxiv topic:physics.class-ph gr-qc quant-ph |
arxiv_dataset-38421211.1954 | Holey Random Walks: Optics of Heterogeneous Turbid Composites
cond-mat.dis-nn cond-mat.stat-mech physics.optics
We present a probabilistic theory of random walks in turbid media with
non-scattering regions. It is shown that important characteristics such as
diffusion constants, average step lengths, crossing statistics and void
spacings can be analytically predicted. The theory is validated using Monte
Carlo simulations of light transport in heterogeneous systems in the form of
random sphere packings, and good agreement is found. The role of step
correlations is discussed, and differences between unbounded and bounded
systems are investigated. Our results are relevant to the optics of
heterogeneous systems in general, and represent an important step forward in
the understanding of media with strong (fractal) heterogeneity in particular.
| arxiv topic:cond-mat.dis-nn cond-mat.stat-mech physics.optics |
arxiv_dataset-38431211.2054 | Detection of an exoplanet around the evolved K giant HD 66141
astro-ph.SR astro-ph.EP
Aims. We have been carrying out a precise radial velocity (RV) survey for K
giants to search for and study the origin of the lowamplitude and long-periodic
RV variations.
Methods. We present high-resolution RV measurements of the K2 giant HD 66141
from December 2003 to January 2011 using the fiber-fed Bohyunsan Observatory
Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO).
Results. We find that the RV measurements for HD 66141 exhibit a periodic
variation of 480.5 +/- 0.5 days with a semi-amplitude of 146.2 +/- 2.7 m/s. The
Hipparcos photometry and bisector velocity span (BVS) do not show any obvious
correlations with RV variations. We find indeed 706.4 +/- 35.0 day variations
in equivalent width (EW) measurements of H_alpha line and 703.0 +/- 39.4 day
variations in a space-born measurements 1.25{\mu} flux of HD 66141 measured
during COBE/DIRBE experiment. We reveal that a mean value of long-period
variations is about 705 +/- 53 days and the origin is a rotation period of the
star and variability that is caused by surface inhomogeneities. For the 480 day
periods of RV variations an orbital motion is the most likely explanation.
Assuming a stellar mass of 1.1 +/- 0.1 M_Sun? for HD 66141, we obtain a minimum
mass for the planetary companion of 6.0 +/- 0.3 M_Jup with an orbital
semi-major axis of 1.2 +/- 0.1 AU and an eccentricity of 0.07 +/- 0.03.
| arxiv topic:astro-ph.SR astro-ph.EP |
arxiv_dataset-38441211.2154 | Testing standard and non-standard neutrino physics with cosmological
data
astro-ph.CO hep-ph
Cosmological constraints on the sum of neutrino masses and on the effective
number of neutrino species in standard and non-standard scenarios are computed
using the most recent available cosmological data. Our cosmological data sets
include the measurement of the Baryonic Acoustic Oscillation (BAO) feature in
the Data Release 9 CMASS sample of the Baryon Oscillation Spectroscopic Survey
(BOSS). We study in detail the different degeneracies among the parameters, as
well as the impact of the different data sets used in the analyses. When
considering bounds on the sum of the three active neutrino masses, the
information in the BAO signal from galaxy clustering measurements is
approximately equally powerful as the shape information from the matter power
spectrum. The most stringent bound we find is sum m_nu<0.32 eV at 95 % CL. When
non-standard neutrino scenarios with neff massless or massive neutrino species
are examined, power spectrum shape measurements provide slightly better bounds
than the BAO signal only, due to the breaking of parameter degeneracies. Recent
BOSS data combined with CMB and Hubble Space Telescope measurements give
neff=3.66^{+0.20 +0.73}_{-0.21 -0.69} in the massless neutrino scenario, and
similar results are obtained in the massive case. The evidence for extra
radiation neff>3 often claimed in the literature therefore remains at the 2
sigma level when considering up-to-date cosmological data sets. Measurements
from the Wilkinson Microwave Anisotropy Probe combined with a prior on the
Hubble parameter from the Hubble Space Telescope are very powerful in
constraining either the sum of the three active neutrino masses or the number
of massless neutrino species. If the former two parameters are allowed to
freely vary, however, the bounds from the combination of these two cosmological
probes get worse by an order of magnitude.
| arxiv topic:astro-ph.CO hep-ph |
arxiv_dataset-38451211.2254 | Illuminating Dark Matter at the ILC
hep-ph
The WIMP (weakly interacting massive particle) paradigm for dark matter is
currently being probed via many different experiments. Direct detection,
indirect detection and collider searches are all hoping to catch a glimpse of
these elusive particles. Here, we examine the potential of the ILC
(International Linear Collider) to shed light on the origin of dark matter. By
using an effective field theory approach we are also able to compare the reach
of the ILC with that of the other searches. We find that for low mass dark
matter (< 10 GeV), the ILC offers a unique opportunity to search for WIMPS
beyond any other experiment. In addition, if dark matter happens to only couple
to leptons or via a spin dependent interaction, the ILC can give an unrivalled
window to these models. We improve on previous ILC studies by constructing a
comprehensive list of effective theories that allows us to move beyond the
non-relativistic approximation.
| arxiv topic:hep-ph |
arxiv_dataset-38461211.2354 | Privacy Preserving Web Query Log Publishing: A Survey on Anonymization
Techniques
cs.DB cs.CR
Releasing Web query logs which contain valuable information for research or
marketing, can breach the privacy of search engine users. Therefore rendering
query logs to limit linking a query to an individual while preserving the data
usefulness for analysis, is an important research problem. This survey provides
an overview and discussion on the recent studies on this direction.
| arxiv topic:cs.DB cs.CR |
arxiv_dataset-38471211.2454 | Wolff-Denjoy theorems in non-smooth convex domains
math.CV math.DS
We give a short proof of Wolff-Denjoy theorem for (not necessarily smooth)
strictly convex domains. With similar techniques we are also able to prove a
Wolff-Denjoy theorem for weakly convex domains, again without any smoothness
assumption on the boundary.
| arxiv topic:math.CV math.DS |
arxiv_dataset-38481211.2554 | Discovery of Volcanic Activity on Io. A Historical Review
physics.hist-ph astro-ph.EP physics.pop-ph
In the 2 March 1979 issue of Science 203 S. J. Peale, P. Cassen and R. T.
Reynolds published their paper "Melting of Io by tidal dissipation" indicating
"the dissipation of tidal energy in Jupiter's moon Io is likely to have melted
a major fraction of the mass." The conclusion of their paper was that
"consequences of a largely molten interior may be evident in pictures of Io's
surface returned by Voyager 1." Just three days after that, the Voyager 1
spacecraft would pass within 0.3 Jupiter radii of Io. The Jet Propulsion
Laboratory navigation team's orbit estimation program as well as the team
members themselves performed flawlessly. In regards to the optical navigation
component image extraction of satellite centers in Voyager pictures taken for
optical navigation at Jupiter rms post fit residuals were less than 0.25
pixels. The cognizant engineer of the Optical Navigation Image Processing
System was astronomer Linda Morabito. Four days after the Voyager 1 encounter
with Jupiter, after preforming image processing on a picture of Io taken by the
spacecraft the day before, something anomalous emerged off the limb of Io. This
historical review written by the discoverer recounts her minute-by-minute quest
to identify what was a volcanic plume, the first evidence of active volcanism
seen beyond Earth. Many ingredients of the account reflect historic themes in
the process of scientific discovery.
| arxiv topic:physics.hist-ph astro-ph.EP physics.pop-ph |
arxiv_dataset-38491211.2654 | Diagrammatic approach to attosecond delays in photoionization
physics.atom-ph quant-ph
We study laser-assisted photoionization by attosecond pulses using a
time-independent formalism based on diagrammatic many-body perturbation theory.
Our aim is to provide an ab inito route to the "delays" for this
above-threshold ionization process, which is essential for a quantitative
understanding of attosecond metrology. We present correction curves for
characterization schemes of attosecond pulses, such as "streaking", that
account for the delayed atomic response in ionization from neon and argon. We
also verify that photoelectron delays from many-electron atoms can be measured
using similar schemes if, instead, the so-called continuum--continuum delay is
subtracted. Our method is general and it can be extended also to more complex
systems and additional correlation effects can be introduced systematically.
| arxiv topic:physics.atom-ph quant-ph |
arxiv_dataset-38501211.2754 | Coal Enterprise Management and Asynchronism of Return
q-fin.PM q-fin.ST
For researching the association between coal enterprise management and return
in financial market, this paper applies the method of time difference relevance
and PageRank method to seek the leader-index of a stock set containing 21 coal
enterprises in A-share market and score those stocks. Based on the return in
2011, the asynchronism of the return series is revealed and presents a
hierarchical structure of our stock set. Finally, we compare the result with
the firm-level variables and discuss the relation between them. The results
show that those large coal enterprises with a good management condition always
present an antecedence of stock return; there is a significant positive
association between company scale and the score given by PageRank method.
| arxiv topic:q-fin.PM q-fin.ST |
arxiv_dataset-38511211.2854 | Using ontology for resume annotation
cs.IR
Employers collect a large number of resumes from job portals, or from the
company's own website. These documents are used for an automated selection of
candidates satisfying the requirements and therefore reducing recruitment
costs. Various approaches for process documents have already been developed for
recruitment. In this paper we present an approach based on semantic annotation
of resumes for e-recruitment process. The most important task consists on
modelling the semantic content of these documents using ontology. The ontology
is built taking into account the most significant components of resumes
inspired from the structure of EUROPASS CV. This ontology is thereafter used to
annotate automatically the resumes.
| arxiv topic:cs.IR |
arxiv_dataset-38521211.2954 | The Futaki invariant on the blowup of K\"ahler surfaces
math.DG
We prove the expansion formula for the classical Futaki invariants on the
blowup of K\"ahler surfaces, which explains the balancing condition of
Arezzo-Pacard. The relation with Stoppa's result is also discussed.
| arxiv topic:math.DG |
arxiv_dataset-38531211.3054 | CTA and cosmic-ray diffusion in molecular clouds
astro-ph.HE
Molecular clouds act as primary targets for cosmic-ray interactions and are
expected to shine in gamma-rays as a by-product of these interactions. Indeed
several detected gamma-ray sources both in HE and VHE gamma-rays (HE: 100 MeV <
E < 100 GeV; VHE: E > 100 GeV) have been directly or indirectly associated with
molecular clouds. Information on the local diffusion coefficient and the local
cosmic-ray population can be deduced from the observed gamma-ray signals. In
this work we concentrate on the capability of the forthcoming Cherenkov
Telescope Array Observatory (CTA) to provide such measurements. We investigate
the expected emission from clouds hosting an accelerator, exploring the
parameter space for different modes of acceleration, age of the source, cloud
density profile, and cosmic ray diffusion coefficient. We present some of the
most interesting cases for CTA regarding this science topic. The simulated
gamma-ray fluxes depend strongly on the input parameters. In some cases, from
CTA data it will be possible to constrain both the properties of the
accelerator and the propagation mode of cosmic rays in the cloud.
| arxiv topic:astro-ph.HE |
arxiv_dataset-38541211.3154 | Charged black holes on the Taub-Bolt instanton
gr-qc hep-th
We construct a new exact solution of the Einstein-Maxwell-Dilaton field
equations in five dimensions, which describes a system of two general charged
and static black holes sitting at the two turning points of the Taub-bolt
instanton. We show that in this case the conical singularities can be
completely eliminated and the black hole system remains in static equilibrium.
We show how to recover some of the known solutions in particular cases and also
obtain as a new solution the extremal double-black hole solution on the
Taub-bolt instanton. Finally, we compute the conserved charges and investigate
some of the thermodynamic properties of this system.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-38551211.3254 | Stable "antiferromagnetic" vortex lattice imprinted into a type-II
superconductor
cond-mat.supr-con
In type-II superconductors, where vortices and antivortices tend to
annihilate, only a "ferromagnetic" vortex lattice, with the same orientation of
vortex magnetic moments, is usually formed in a homogeneous external magnetic
field. Using the time-dependent Ginzburg-Landau formalism, we demonstrate that
a checkerboard vortex-antivortex lattice ("antiferromagnetic vortex lattice"),
imprinted onto a superconducting film by a periodic array of underlying
clockwise and counterclockwise microcoils generating spatially periodic
positive and negative magnetic field pulses and then trapped by an array of
artificial pinning centers, remains stable even after the imprinting magnetic
field pulse is switched off.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-38561211.3354 | Analysis of Compatible Discrete Operator Schemes for Elliptic Problems
on Polyhedral Meshes
math.NA
Compatible schemes localize degrees of freedom according to the physical
nature of the underlying fields and operate a clear distinction between
topological laws and closure relations. For elliptic problems, the cornerstone
in the scheme design is the discrete Hodge operator linking gradients to fluxes
by means of a dual mesh, while a structure-preserving discretization is
employed for the gradient and divergence operators. The discrete Hodge operator
is sparse, symmetric positive definite and is assembled cellwise from local
operators. We analyze two schemes depending on whether the potential degrees of
freedom are attached to the vertices or to the cells of the primal mesh. We
derive new functional analysis results on the discrete gradient that are the
counterpart of the Sobolev embeddings. Then, we identify the two design
properties of the local discrete Hodge operators yielding optimal discrete
energy error estimates. Additionally, we show how these operators can be built
from local nonconforming gradient reconstructions using a dual barycentric
mesh. In this case, we also prove an optimal $L^2$-error estimate for the
potential for smooth solutions. Links with existing schemes (finite elements,
finite volumes, mimetic finite differences) are discussed. Numerical results
are presented on three-dimensional polyhedral meshes.
| arxiv topic:math.NA |
arxiv_dataset-38571211.3454 | On tensor products of semistable lattices
math.MG
We give an elementary proof of low rank cases of the conjecture that the
tensor product of two semistable Euclidean lattices is again semistable.
| arxiv topic:math.MG |
arxiv_dataset-38581211.3554 | The distribution of warm gas in the G327.3--0.6 massive star-forming
region
astro-ph.GA
Most studies of high-mass star formation focus on massive luminous clumps,
but the physical properties of their larger scale environment are poorly known.
In this work, we aim at characterising the effects of clustered star formation
and feedback of massive stars on the surrounding medium by studying the
distribution of warm gas through mid-J 12CO and 13CO data. We present APEX
12CO(6-5), (7-6), 13CO(6-5), (8-7) and HIFI 13CO(10-9) maps of the star forming
region G327.36-0.6. We infer the physical properties of the emitting gas on
large scales through a LTE analysis, while we apply a more sophisticated LVG
approach on selected positions. Maps of all lines are dominated in intensity by
the PDR around the Hii region G327.3-0.5. Mid-J 12CO emission is detected over
the whole extent of the maps with excitation temperatures ranging from 20K up
to 80K in the gas around the Hii region, and H2 column densities from few 10^21
cm-2 in the inter-clump gas to 3 10^22 cm-2 towards the hot core G327.3-0.6.
The warm gas (traced by 12 and 13CO(6-5) emission) is only a small percentage
(10%) of the total gas in the IRDC, while it reaches values up to 35% of the
total gas in the ring surrounding the Hii region. The 12CO ladders are
qualitatively compatible with PDR models for high density gas, but the much
weaker than predicted 13CO emission suggests that it comes from a large number
of clumps along the line of sight. All lines are detected in the inter-clump
gas when averaged over a large region with an equivalent radius of 50"
(~0.8pc), implying that the mid-J 12CO and 13CO inter-clump emission is due to
high density components with low filling factor. Finally, the detection of the
13CO(10-9) line allows to disentangle the effects of gas temperature and gas
density on the CO emission, which are degenerate in the APEX observations
alone.
| arxiv topic:astro-ph.GA |
arxiv_dataset-38591211.3654 | Non-anticommutativity in Presence of a Boundary
hep-th
In this paper we consider non-anticommutative field theories in $\mathcal{N}
=2$ superspace formalism on three-dimensional manifolds with a boundary. We
modify the original Lagrangian in such a way that it preserves half the
supersymmetry even in the presence of a boundary. We also analyse the partial
breaking of supersymmetry caused by non-anticommutativity between fermionic
coordinates. Unlike in four dimensions, in three dimensions a theory with
$\mathcal{N} =1/2$ supersymmetry cannot be obtained by a non-anticommutative
deformation of an $\mathcal{N} =1$ theory. However, in this paper we construct
a three dimensional theory with $\mathcal{N} =1/2$ supersymmetry by studying a
combination of non-anticommutativity and boundary effects, starting from
$\mathcal{N} =2$ supersymmetry.
| arxiv topic:hep-th |
arxiv_dataset-38601211.3754 | Recursive Robust PCA or Recursive Sparse Recovery in Large but
Structured Noise
cs.IT math.IT
This work studies the recursive robust principal components' analysis(PCA)
problem. Here, "robust" refers to robustness to both independent and correlated
sparse outliers. If the outlier is the signal-of-interest, this problem can be
interpreted as one of recursively recovering a time sequence of sparse vectors,
St, in the presence of large but structured noise, Lt. The structure that we
assume on Lt is that Lt is dense and lies in a low dimensional subspace that is
either fixed or changes "slowly enough". A key application where this problem
occurs is in video surveillance where the goal is to separate a slowly changing
background (Lt) from moving foreground objects (St) on-the-fly. To solve the
above problem, we introduce a novel solution called Recursive Projected CS
(ReProCS). Under mild assumptions, we show that, with high probability
(w.h.p.), ReProCS can exactly recover the support set of St at all times; and
the reconstruction errors of both St and Lt are upper bounded by a
time-invariant and small value at all times.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-38611211.3854 | Why is surface tension a force parallel to the interface?
physics.flu-dyn cond-mat.soft
A paperclip can float on water. Drops of mercury refuse to spread on a
surface. These capillary phenomena are macroscopic manifestations of molecular
interactions, and can be explained in terms of surface tension. For students,
the concept of surface tension is quite challenging since the microscopic
intuition is often in conflict with the common macroscopic interpretations. In
this paper we address a number of conceptual questions that are often
encountered when teaching capillarity. By answering these questions we provide
a perspective that reconciles the macroscopic viewpoints, from thermodynamics
or fluid mechanics, and the microscopic perspective from statistical physics.
| arxiv topic:physics.flu-dyn cond-mat.soft |
arxiv_dataset-38621211.3954 | Tunneling Spectroscopy of Quasiparticle Bound States in a Spinful
Josephson Junction
cond-mat.mes-hall cond-mat.supr-con
The spectrum of a segment of InAs nanowire, confined between two
superconducting leads, was measured as function of gate voltage and
superconducting phase difference using a third normal-metal tunnel probe.
Sub-gap resonances for odd electron occupancy---interpreted as bound states
involving a confined electron and a quasiparticle from the superconducting
leads, reminiscent of Yu-Shiba-Rusinov states---evolve into Kondo-related
resonances at higher magnetic fields. An additional zero bias peak of unknown
origin is observed to coexist with the quasiparticle bound states.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-38631211.4054 | Bounds on universal quantum computation with perturbed 2d cluster states
cond-mat.str-el quant-ph
Motivated by the possibility of universal quantum computation under noise
perturbations, we compute the phase diagram of the 2d cluster state Hamiltonian
in the presence of Ising terms and magnetic fields. Unlike in previous analysis
of perturbed 2d cluster states, we find strong evidence of a very well defined
cluster phase, separated from a polarized phase by a line of 1st and 2nd order
transitions compatible with the 3d Ising universality class and a tricritical
end point. The phase boundary sets an upper bound for the amount of
perturbation in the system so that its ground state is still useful for
measurement-based quantum computation purposes. Moreover, we also compute the
local fidelity with the unperturbed 2d cluster state. Besides a classical
approximation, we determine the phase diagram by combining series expansions
and variational infinite Projected entangled-Pair States (iPEPS) methods. Our
work constitutes the first analysis of the non-trivial effect of few-body
perturbations in the 2d cluster state, which is of relevance for experimental
proposals.
| arxiv topic:cond-mat.str-el quant-ph |
arxiv_dataset-38641211.4154 | Energy and regularity dependent stability estimates for near-field
inverse scattering in multidimensions
math.AP
We prove new global H\"older-logarithmic stability estimates for the
near-field inverse scattering problem in dimension $d\geq 3$. Our estimates are
given in uniform norm for coefficient difference and related stability
efficiently increases with increasing energy and/or coefficient regularity. In
addition, a global logarithmic stability estimate for this inverse problem in
dimension $d=2$ is also given.
| arxiv topic:math.AP |
arxiv_dataset-38651211.4254 | Minimum CSIT to achieve Maximum Degrees of Freedom for the MISO BC
cs.IT math.IT
Channel state information at the transmitter (CSIT) is a key ingredient in
realizing the multiplexing gain provided by distributed MIMO systems. For a
downlink multiple-input single output (MISO) broadcast channel, with M antennas
at the transmitters and K single antenna receivers, the maximum multiplexing
gain or the maximum degrees of freedom (DoF) is min(M,K). The optimal DoF of
min(M,K) is achievable if the transmitter has access to perfect, instantaneous
CSIT from all receivers. In this paper, we pose the question that what is
minimum amount of CSIT required per user in order to achieve the maximum DoF of
min(M,K). By minimum amount of CSIT per user, we refer to the minimum fraction
of time that the transmitter has access to perfect and instantaneous CSIT from
a user. Through a novel converse proof and an achievable scheme, it is shown
that the minimum fraction of time, perfect CSIT is required per user in order
to achieve the DoF of min(M,K) is given by min(M,K)/K.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-38661211.4354 | Convergent Analytic Solutions for Homoclinic Orbits in Reversible and
Non-reversible Systems
math.DS math-ph math.MP
In this paper, convergent, multi-infinite, series solutions are derived for
the homoclinic orbits of a canonical fourth-order ODE system, in both
reversible and non-reversible cases. This ODE includes traveling-wave
reductions of many important nonlinear PDEs or PDE systems, for which these
analytical solutions would correspond to regular or localized pulses of the
PDE. As such, the homoclinic solutions derived here are clearly topical, and
they are shown to match closely to earlier results obtained by homoclinic
numerical shooting. In addition, the results for the non-reversible case go
beyond those that have been typically considered in analyses conducted within
bifurcation-theoretic settings.
We also comment on generalizing the treatment here to parameter regimes where
solutions homoclinic to exponentially small periodic orbits are known to exist,
as well as another possible extension placing the solutions derived here within
the framework of a comprehensive categorization of ALL possible traveling-wave
solutions, both smooth and non-smooth, for our governing ODE.
| arxiv topic:math.DS math-ph math.MP |
arxiv_dataset-38671211.4454 | Semi-classical unitarity in 3-dimensional higher-spin gravity for
non-principal embeddings
hep-th gr-qc
Higher-spin gravity in three dimensions is efficiently formulated as a
Chern-Simons gauge-theory, typically with gauge algebra sl(N)+sl(N). The
classical and quantum properties of the higher-spin theory depend crucially on
the embedding into the full gauge algebra of the sl(2)+sl(2) factor associated
with gravity. It has been argued previously that non-principal embeddings do
not allow for a semi-classical limit (large values of the central charge)
consistent with unitarity. In this work we show that it is possible to
circumvent these conclusions. Based upon the Feigin-Semikhatov generalization
of the Polyakov-Bershadsky algebra, we construct infinite families of unitary
higher-spin gravity theories at certain rational values of the Chern-Simons
level that allow arbitrarily large values of the central charge up to c = N/4 -
1/8 - O(1/N), thereby confirming a recent speculation by us 1209.2860.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-38681211.4554 | Huneke-Wiegand Conjecture for Complete Intersection Numerical Semigroup
Rings
math.AC math.NT
We give a positive answer to the Huneke-Wiegand Conjecture for monomial
ideals over free numerical semigroup rings, and for two generated monomial
ideals over complete intersection numerical semigroup rings.
| arxiv topic:math.AC math.NT |
arxiv_dataset-38691211.4654 | Application of Data mining in Protein sequence Classification
cs.CE
Protein sequence classification involves feature selection for accurate
classification. Popular protein sequence classification techniques involve
extraction of specific features from the sequences. Researchers apply some
well-known classification techniques like neural networks, Genetic algorithm,
Fuzzy ARTMAP,Rough Set Classifier etc for accurate classification. This paper
presents a review is with three different classification models such as neural
network model, fuzzy ARTMAP model and Rough set classifier model. This is
followed by a new technique for classifying protein sequences. The proposed
model is typically implemented with an own designed tool and tries to reduce
the computational overheads encountered by earlier approaches and increase the
accuracy of classification
| arxiv topic:cs.CE |
arxiv_dataset-38701211.4754 | Generalized Newton transformation and its applications to extrinsic
geometry
math.DG
In this article we introduce a generalization of the Newton transformation to
the case of a system of endomorphisms. We show that it can be used in the
context of extrinsic geometry of foliations and distributions yielding new
integral formulas containing generalized extrinsic curvatures.
| arxiv topic:math.DG |
arxiv_dataset-38711211.4854 | Narrow and $\ell_2$-strictly singular operators from $L_p$
math.FA
In the first part of the paper we prove that for $2 < p, r < \infty$ every
operator $T: L_p \to \ell_r$ is narrow. This completes the list of sequence and
function Lebesgue spaces $X$ with the property that every operator $T:L_p \to
X$ is narrow.
Next, using similar methods we prove that every $\ell_2$-strictly singular
operator from $L_p$, $1<p<\infty$, to any Banach space with an unconditional
basis, is narrow, which partially answers a question of Plichko and Popov posed
in 1990.
A theorem of H. P. Rosenthal asserts that if an operator $T$ on $L_1[0,1]$
satisfies the assumption that for each measurable set $A \subseteq [0,1]$ the
restriction $T \bigl|_{L_1(A)}$ is not an isomorphic embedding, then $T$ is
narrow.
(Here $L_1(A) = \{x \in L_1: {\rm supp} \, x \subseteq A\}$.) Inspired by
this result, in the last part of the paper, we find a sufficient condition, of
a different flavor than being $\ell_2$-strictly singular, for operators on
$L_p[0,1]$, $1<p<2$, to be narrow. We define a notion of a "gentle" growth of a
function and we prove that for $1 < p < 2$ every operator $T$ on $L_p$ which,
for every $A\subseteq[0,1]$, sends a function of "gentle" growth supported on
$A$ to a function of arbitrarily small norm is narrow.
| arxiv topic:math.FA |
arxiv_dataset-38721211.4954 | Dissipation effect in the double-well Bose-Einstein Condensate
cond-mat.quant-gas
Dynamics of the double-well Bose-Einstein condensate subject to energy
dissipation is studied by solving a reduced one-dimensional time-dependent
Gross-Pitaevskii equation numerically. We first reproduce the phase space
diagram of the system without dissipation systematically, and then calculate
evolutionary trajectories of dissipated systems. It is clearly shown that the
dissipation can drive the system to evolve gradually from the $\pi$-mode
quantum macroscopic self-trapping state, a state with relatively higher energy,
to the lowest energy stationary state in which particles distribute equally in
the two wells. The average phase and phase distribution in each well are
discussed as well. We show that the phase distribution varies slowly in each
well but may exhibit abrupt changes near the barrier. This sudden change occurs
at the minimum position in particle density profile. We also note that the
average phase in each well varies much faster with time than the phase
difference between two wells.
| arxiv topic:cond-mat.quant-gas |
arxiv_dataset-38731211.5054 | Transfer of R-groups between p-adic inner forms of SL_n
math.RT
We study the Knapp-Stein $R$--groups for inner forms of the split group
$SL_n(F),$ with $F$ a $p$--adic field of characteristic zero. Thus, we consider
the groups $SL_m(D),$ with $D$ a central division algebra over $F$ of dimension
$d^2,$ and $m=n/d.$ We use the generalized Jacquet-Langlands correspondence and
results of the first named author to describe the zeros of Plancherel measures.
Combined with a study of the behavior of the stabilizer of representations by
elements of the Weyl group we are able to determine the Knapp-Stein $R$--groups
in terms of those for $SL_n(F).$ We show the $R$--group for the inner form
embeds as a subgroup of the $R$--group for the split form, and we characterize
the quotient. We are further able to show the Knapp-Stein $R$--group is
isomorphic to the Arthur, or Endoscopic $R$--group as predicted by Arthur.
Finally, we give some results on multiplicities and actions of Weyl groups on
$L$--packets.
| arxiv topic:math.RT |
arxiv_dataset-38741211.5154 | Neutralino dark matter and the Fermi gamma-ray lines
hep-ph astro-ph.CO astro-ph.HE
Motivated by recent claims of lines in the Fermi gamma-ray spectrum, we
critically examine means of enhancing neutralino annihilation into neutral
gauge bosons. The signal can be boosted while remaining consistent with
continuum photon constraints if a new singlet-like pseudoscalar is present. We
consider singlet extensions of the MSSM, focusing on the NMSSM, where a
`well-tempered' neutralino can explain the lines while remaining consistent
with current constraints. We adopt a complementary numerical and analytic
approach throughout in order to gain intuition for the underlying physics. The
scenario requires a rich spectrum of light neutralinos and charginos leading to
characteristic phenomenological signatures at the LHC whose properties we
explore. Future direct detection prospects are excellent, with sizeable
spin-dependent and spin-independent cross-sections.
| arxiv topic:hep-ph astro-ph.CO astro-ph.HE |
arxiv_dataset-38751211.5254 | III-V quantum light source and cavity-QED on Silicon
cond-mat.mes-hall cond-mat.mtrl-sci
Non-classical light sources offer a myriad of possibilities in fundamental
science and applications including quantum cryptography and quantum
lithography. Single photons can encode quantum information and multi-qubit
gates in silica waveguide circuits have been used to demonstrate linear optical
quantum computing. Scale-up requires miniaturisation of the waveguide circuit
and multiple photon sources. Silicon photonics, driven by the incentive of
optical interconnects, is a highly promising platform for the passive
components, but integrated light sources are limited by silicon's indirect
band-gap. III-V semiconductor quantum-dots, on the other hand, are proven
quantum emitters. Here we demonstrate single-photon emission from quantum-dots
coupled to photonic crystal nanocavities fabricated from III-V material grown
directly on silicon substrates. The high quality of the III-V material and
photonic structures is emphasized by observation of the strong-coupling regime.
This work opens-up the advantages of silicon photonics to the integration and
scale-up of solid-state quantum optical systems.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-38761211.5354 | Is dark matter made of mirror matter? Evidence from cosmological data
astro-ph.CO hep-ph
We present new fast numerical simulations of cosmic microwave background and
large scale structure in the case in which the cosmological dark matter is made
entirely or partly of mirror matter. We consider scalar adiabatic primordial
perturbations at linear scales in a flat Universe. The speed of the simulations
allows us for the first time to use Markov Chain Monte Carlo analyses to
constrain the mirror parameters. A Universe with pure mirror matter can fit
very well the observations, equivalently to the case of an admixture with cold
dark matter. In both cases, the analyses show a clear indication of the
presence of a consistent amount of mirror dark matter, $0.06 \lesssim
\Omega_{\rm mirror} h^2 \lesssim 0.12$.
| arxiv topic:astro-ph.CO hep-ph |
arxiv_dataset-38771211.5454 | A Newton method for simultaneous reconstruction of an interface and a
buried obstacle from far-field data
math.NA
This paper is concerned with the inverse problem of scattering of
time-harmonic acoustic waves from a penetrable and buried obstacles. By
introducing a related transmission scattering problem, a Newton iteration
method is proposed to simultaneously reconstruct both the penetrable interface
and the buried obstacle inside from far-field data. A main feature of our
method is that we do not need to know the type of boundary conditions on the
buried obstacle. In particular, the boundary condition on the buried obstacle
can also be determined simultaneously by the method. Finally, numerical
examples using multi-frequency data are carried out to illustrate the
effectiveness of our method.
| arxiv topic:math.NA |
arxiv_dataset-38781211.5554 | Quantum Hypergraph States
quant-ph
We introduce a class of multiqubit quantum states which generalizes graph
states. These states correspond to an underlying mathematical hypergraph, i.e.
a graph where edges connecting more than two vertices are considered. We derive
a generalised stabilizer formalism to describe this class of states. We
introduce the notion of k-uniformity and show that this gives rise to classes
of states which are inequivalent under the action of the local Pauli group.
Finally we disclose a one-to-one correspondence with states employed in quantum
algorithms, such as Deutsch-Jozsa's and Grover's.
| arxiv topic:quant-ph |
arxiv_dataset-38791211.5654 | Effects of Quantum Error Correction on Entanglement Sudden Death
quant-ph
We investigate the effects of error correction on non-local quantum coherence
as a function of time, extending the study by Sainz and Bj\"ork. We consider
error correction of amplitude damping, pure phase damping and combinations of
amplitude and phase damping as they affect both fidelity and quantum
entanglement. Initial two-qubit entanglement is encoded in arbitrary real
superpositions of both \Phi-type and \Psi-type Bell states. Our main focus is
on the possibility of delay or prevention of ESD (early stage decoherence, or
entanglement sudden death). We obtain the onset times for ESD as a function of
the state-superposition mixing angle. Error correction affects entanglement and
fidelity differently, and we exhibit initial entangled states for which error
correction increases fidelity but decreases entanglement, and vice versa.
| arxiv topic:quant-ph |
arxiv_dataset-38801211.5754 | Stability of Trionic States in Zigzag Carbon Nanotubes
cond-mat.mes-hall cond-mat.other cond-mat.str-el
The stability of trionic excitations in zigzag carbon nanotubes has been
estimated. A trion is shown to be unstable with respect to the ground excitonic
state and stable with respect to the excited one. So, trions in nanotubes of
this type can be formed by capturing an electron or a hole by an excited
exciton. In other words, the trion in a nanotube is an excimer complex, which
results in the formation of a system with three energy levels (unexcited
exciton--trion--excited exciton).
| arxiv topic:cond-mat.mes-hall cond-mat.other cond-mat.str-el |
arxiv_dataset-38811211.5854 | Feedback from High-Mass X-Ray Binaries on the High Redshift
Intergalactic Medium : Model Spectra
astro-ph.CO astro-ph.HE
Massive stars at redshifts z > 6 are predicted to have played a pivotal role
in cosmological reionization as luminous sources of ultra-violet (UV) photons.
However, the remnants of these massive stars could be equally important as
X-ray luminous (L_X 1e38 erg/s) high-mass X-ray binaries (HMXBs). Because the
absorption cross section of neutral hydrogen decreases sharply with photon
energy (proportional to the inverse cube), X-rays can escape more freely than
UV photons from the star-forming regions in which they are produced, allowing
HMXBs to make a potentially significant contribution to the ionizing X-ray
background during reionization. In this paper, we explore the ionizing power of
HMXBs at redshifts z > 6 using a Monte Carlo model for a coeval stellar
population of main sequence stars and HMXBs. Using the archetypal Galactic HMXB
Cygnus X-1 as our template, we propose a composite HMXB spectral energy
distribution consisting of black-body and power-law components, whose
contributions depend on the accretion state of the system. We determine the
time-dependent ionizing power of a combined population of UV-luminous stars and
X-ray luminous HMXBs, and deduce fitting formulae for the boost in the
population's ionizing power arising from HMXBs; these fits allow for simple
implementation of HMXB feedback in numerical simulations. Based on this
analysis, we estimate the contribution of high redshift HMXBs to the
present-day soft X-ray background, and we show that it is a factor of ~100-1000
smaller than the observed limit. Finally, we discuss the implications of our
results for the role of HMXBs in reionization and in high redshift galaxy
formation.
| arxiv topic:astro-ph.CO astro-ph.HE |
arxiv_dataset-38821211.5954 | Oversampling for the Multiscale Finite Element Method
math.NA
This paper reviews standard oversampling strategies as performed in the
Multiscale Finite Element Method (MsFEM). Common to those approaches is that
the oversampling is performed in the full space restricted to a patch but
including coarse finite element functions. We suggest, by contrast, to perform
local computations with the additional constraint that trial and test functions
are linear independent from coarse finite element functions. This approach
re-interprets the Variational Multiscale Method in the context of computational
homogenization. This connection gives rise to a general fully discrete error
analysis for the proposed multiscale method with constrained oversampling
without any resonance effects. In particular, we are able to give the first
rigorous proof of convergence for a MsFEM with oversampling.
| arxiv topic:math.NA |
arxiv_dataset-38831211.6054 | Integrally closed rings in birational extensions of two-dimensional
regular local rings
math.AC
Let $D$ be an integrally closed local Noetherian domain of Krull dimension 2,
and let $f$ be a nonzero element of $D$ such that $fD$ has prime radical. We
consider when an integrally closed ring $H$ between $D$ and $D_f$ is determined
locally by finitely many valuation overrings of $D$. We show such a local
determination is equivalent to a statement about the exceptional prime divisors
of normalized blow-ups of $D$, and, when $D$ is analytically normal, this
property holds for $D$ if and only if it holds for the completion of $D$. This
latter fact, along with MacLane's notion of key polynomials, allows us to prove
that in some central cases where $D$ is a regular local ring and $f$ is a
regular parameter of $D$, then $H$ is determined locally by a single valuation.
As a consequence, we show that if $H$ is also the integral closure of a
finitely generated $D$-algebra, then the exceptional prime ideals of the
extension $H/D$ are comaximal. Geometrically, this translates into a statement
about intersections of irreducible components in the closed fiber of the
normalization of a proper birational morphism.
| arxiv topic:math.AC |
arxiv_dataset-38841211.6154 | Hamiltonian dynamics of a particle interacting with a wave field
math-ph math.AP math.MP
We study the Hamiltonian equations of motion of a heavy tracer particle
interacting with a dense weakly interacting Bose-Einstein condensate in the
classical (mean-field) limit. Solutions describing ballistic subsonic motion of
the particle through the condensate are constructed. We establish asymptotic
stability of ballistic subsonic motion.
| arxiv topic:math-ph math.AP math.MP |
arxiv_dataset-38851211.6254 | Recognition of collapsible complexes is NP-complete
cs.CG
We prove that it is NP-complete to decide whether a given (3-dimensional)
simplicial complex is collapsible. This work extends a result of Malgouyres and
Franc\'{e}s showing that it is NP-complete to decide whether a given simplicial
complex collapses to a 1-complex.
| arxiv topic:cs.CG |
arxiv_dataset-38861211.6354 | An equation linking $\mathscr{W}$-entropy with reduced volume
math.DG math.AP
$\mathscr{W}$-entropy and reduced volume for the Ricci flow were introduced
by Perelman, which had proved their importance in the study of the Ricci flow.
L. Ni studied the analogous concepts for the linear heat equation on the static
manifolds, and established an equation which links the large time behavior of
these two. Due to the surprising similarity between those concepts in the Ricci
flow and the linear heat equation, a natural question whether such equation
holds for the Ricci flow ancient solution was asked by L. Ni. In this paper, we
gave an alternative proof to L. Ni's original equation based on a new method.
And following the same philosophy of this method, we answer L. Ni's question
positively for Type I $\kappa$-solutions of the Ricci flow.
| arxiv topic:math.DG math.AP |
arxiv_dataset-38871211.6454 | Anisotropic Impurity-States, Quasiparticle Scattering and Nematic
Transport in Underdoped Ca(Fe1-xCox)2As2
cond-mat.supr-con
Iron-based high temperature superconductivity develops when the `parent'
antiferromagnetic/orthorhombic phase is suppressed, typically by introduction
of dopant atoms. But their impact on atomic-scale electronic structure, while
in theory quite complex, is unknown experimentally. What is known is that a
strong transport anisotropy with its resistivity maximum along the crystal
b-axis, develops with increasing concentration of dopant atoms; this
`nematicity' vanishes when the `parent' phase disappears near the maximum
superconducting Tc. The interplay between the electronic structure surrounding
each dopant atom, quasiparticle scattering therefrom, and the transport
nematicity has therefore become a pivotal focus of research into these
materials. Here, by directly visualizing the atomic-scale electronic structure,
we show that substituting Co for Fe atoms in underdoped Ca(Fe1-xCox)2As2
generates a dense population of identical anisotropic impurity states. Each is
~8 Fe-Fe unit cells in length, and all are distributed randomly but aligned
with the antiferromagnetic a-axis. By imaging their surrounding interference
patterns, we further demonstrate that these impurity states scatter
quasiparticles in a highly anisotropic manner, with the maximum scattering rate
concentrated along the b-axis. These data provide direct support for the recent
proposals that it is primarily anisotropic scattering by dopant-induced
impurity states that generates the transport nematicity; they also yield simple
explanations for the enhancement of the nematicity proportional to the dopant
density and for the occurrence of the highest resistivity along the b-axis.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-38881211.6554 | Microwave Near-Field Quantum Control of Trapped Ions
quant-ph physics.atom-ph
Microwave near-field quantum control of spin and motional degrees of freedom
of 25Mg+ ions can be used to generate two-ion entanglement, as recently
demonstrated in Ospelkaus et al. [Nature 476, 181 (2011)]. Here, we describe
additional details of the setup and calibration procedures for these
experiments. We discuss the design and characteristics of the surface-electrode
trap and the microwave system, and compare experimental measurements of the
microwave near-fields with numerical simulations. Additionally, we present a
method that utilizes oscillating magnetic-field gradients to detect micromotion
induced by the ponderomotive radio-frequency potential in linear traps.
Finally, we discuss the present limitations of microwave-driven two-ion
entangling gates in our system.
| arxiv topic:quant-ph physics.atom-ph |
arxiv_dataset-38891211.6654 | Electron-photon correlations and the third moment of quantum noise
cond-mat.mes-hall
The radiation generated by a quantum conductor should be correlated with
electrons crossing it. We have measured the correlation between the
fluctuations of the high frequency electromagnetic power and the low frequency
transport in a tunnel junction. We have explored the regimes where
electromagnetic fluctuations correspond to real photons and where they
correspond to vacuum at very low temperature. We deduce from our data the
intrinsic third moment of quantum shot noise, which appears to be frequency
independent.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-38901211.6754 | Bar formation and evolution in disc galaxies with gas and a triaxial
halo: Morphology, bar strength and halo properties
astro-ph.CO astro-ph.GA
We follow the formation and evolution of bars in N-body simulations of disc
galaxies with gas and/or a triaxial halo. We find that both the relative gas
fraction and the halo shape play a major role in the formation and evolution of
the bar. In gas-rich simulations, the disc stays near-axisymmetric much longer
than in gas-poor ones, and, when the bar starts growing, it does so at a much
slower rate. Due to these two effects combined, large-scale bars form much
later in gas-rich than in gas-poor discs. This can explain the observation that
bars are in place earlier in massive red disc galaxies than in blue spirals. We
also find that the morphological characteristics in the bar region are strongly
influenced by the gas fraction. In particular, the bar at the end of the
simulation is much weaker in gas-rich cases. In no case did we witness bar
destruction.
Halo triaxiality has a dual influence on bar strength. In the very early
stages of the simulation it induces bar formation to start earlier. On the
other hand, during the later, secular evolution phase, triaxial haloes lead to
considerably less increase of the bar strength than spherical ones. The shape
of the halo evolves considerably with time. The inner halo parts may become
more elongated, or more spherical, depending on the bar strength. The main body
of initially triaxial haloes evolves towards sphericity, but in initially
strongly triaxial cases it stops well short of becoming spherical. Part of the
angular momentum absorbed by the halo generates considerable rotation of the
halo particles that stay located relatively near the disc for long periods of
time. Another part generates halo bulk rotation, which, contrary to that of the
bar, increases with time but stays small.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-38911211.6854 | Magnetic field induced valence band mixing in [111] grown semiconductor
quantum dots
cond-mat.mes-hall
We present a microscopic theory of the magnetic field induced mixing of
heavy-hole states +/- 3/2 in GaAs droplet dots grown on (111)A substrates. The
proposed theoretical model takes into account the striking dot shape with
trigonal symmetry revealed in atomic force microscopy. Our calculations of the
hole states are carried out within the Luttinger Hamiltonian formalism,
supplemented with allowance for the triangularity of the confining potential.
They are in quantitative agreement with the experimentally observed
polarization selection rules, emission line intensities and energy splittings
in both longitudinal and transverse magnetic fields for neutral and charged
excitons in all measured single dots.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-38921211.6954 | Structural Parameters of Galaxies in CANDELS
astro-ph.CO
We present global structural parameter measurements of 109,533 unique,
H_F160W-selected objects from the CANDELS multi-cycle treasury program. Sersic
model fits for these objects are produced with GALFIT in all available
near-infrared filters (H_F160W, J_F125W and, for a subset, Y_F105W). The
parameters of the best-fitting Sersic models (total magnitude, half-light
radius, Sersic index, axis ratio, and position angle) are made public, along
with newly constructed point spread functions for each field and filter. Random
uncertainties in the measured parameters are estimated for each individual
object based on a comparison between multiple, independent measurements of the
same set of objects. To quantify systematic uncertainties we create a mosaic
with simulated galaxy images with a realistic distribution of input parameters
and then process and analyze the mosaic in an identical manner as the real
data. We find that accurate and precise measurements -- to 10% or better -- of
all structural parameters can typically be obtained for galaxies with H_F160W <
23, with comparable fidelity for basic size and shape measurements for galaxies
to H_F160W ~ 24.5.
| arxiv topic:astro-ph.CO |
arxiv_dataset-38931211.7054 | Dark Energy or Modified Gravity? An Effective Field Theory Approach
astro-ph.CO gr-qc hep-th
We take an Effective Field Theory (EFT) approach to unifying existing
proposals for the origin of cosmic acceleration and its connection to
cosmological observations. Building on earlier work where EFT methods were used
with observations to constrain the background evolution, we extend this program
to the level of the EFT of the cosmological perturbations - following the
example from the EFT of Inflation. Within this framework, we construct the
general theory around an assumed background which will typically be chosen to
mimic Lambda-CDM, and identify the parameters of interest for constraining dark
energy and modified gravity models with observations. We discuss the
similarities to the EFT of Inflation, but we also identify a number of
subtleties including the relationship between the scalar perturbations and the
Goldstone boson of the spontaneously broken time translations. We present
formulae that relate the parameters of the fundamental Lagrangian to the speed
of sound, anisotropic shear stress, effective Newtonian constant, and
Caldwell's varpi parameter emphasizing the connection to observations. It is
anticipated that this framework will be of use in constraining individual
models, as well as for placing model-independent constraints on dark energy and
modified gravity model building.
| arxiv topic:astro-ph.CO gr-qc hep-th |
arxiv_dataset-38941211.7154 | Constrained metric variations and emergent equilibrium surfaces
cond-mat.soft gr-qc math-ph math.MP
Any surface is completely characterized by a metric and a symmetric tensor
satisfying the Gauss-Codazzi-Mainardi equations (GCM), which identifies the
latter as its curvature. We demonstrate that physical questions relating to a
surface described by any Hamiltonian involving only surface degrees of freedom
can be phrased completely in terms of these tensors without explicit reference
to the ambient space: the surface is an emergent entity. Lagrange multipliers
are introduced to impose GCM as constraints on these variables and equations
describing stationary surface states derived. The behavior of these multipliers
is explored for minimal surfaces, showing how their singularities correlate
with surface instabilities.
| arxiv topic:cond-mat.soft gr-qc math-ph math.MP |
arxiv_dataset-38951211.7254 | Geodesic distance for right invariant Sobolev metrics of fractional
order on the diffeomorphism group. II
math.DG math.AP
The geodesic distance vanishes on the group of compactly supported
diffeomorphisms of a Riemannian manifold $M$ of bounded geometry, for the right
invariant weak Riemannian metric which is induced by the Sobolev metric $H^s$
of order $0\le s<\tfrac12$ on the Lie algebra $\mathfrak X_c(M)$ of vector
fields with compact support.
| arxiv topic:math.DG math.AP |
arxiv_dataset-38961211.7354 | Chaos in the mixed even-spin models
math.PR math-ph math.MP
We consider a disordered system obtained by coupling two mixed even-spin
models together. The chaos problem is concerned with the behavior of the
coupled system when the external parameters in the two models, such as,
temperature, disorder, or external field, are slightly different. It is
conjectured that the overlap between two independently sampled spin
configurations from, respectively, the Gibbs measures of the two models is
essentially concentrated around a constant under the coupled Gibbs measure.
Using the extended Guerra replica symmetry breaking bound together with a
recent development of controlling the overlap using the Ghirlanda-Guerra
identities as well as a new family of identities, we present rigorous results
on chaos in temperature. In addition, chaos in disorder and in external field
are addressed.
| arxiv topic:math.PR math-ph math.MP |
arxiv_dataset-38971212.0084 | A survey of CO and its isotope lines for possible cloud-cloud collision
candidates
astro-ph.SR astro-ph.GA
In the 12CO (J=1-0) survey for the 1331 cold IRAS sources 214 sources show
profiles with multiple-peak profiles and are selected as cloud-cloud collision
candidates. In January 2005, 201 sources are detected with 12CO(1-0),
13CO(1-0), and C18O(1-0) emission by the 13.7m telescope at Purple Mount
Observatory. This is the first CO and its isotope lines directed toward
possible cloud-cloud collision regions. According to the statistics of the 201
sources in Galactic distribution, the 201 sources show a similar distribution
to the parent sample (1331 cold IRAS sources). These sources are located over a
wide range of the Galactocentric distances, and are partly associated with the
star formation region. Based on preliminary criteria which describe the
spectrum properties of the possible cloud-cloud collision region, the 201
sources are classified into four types by the fit of the spectral profiles
between the optically thick and thin lines toward each source. The survey is
focused on the possible cloud-cloud collision regions, and gives some evidences
to help us with selecting the target region. Then we will carry on the mapping
and multi-wavelength study for the selected region in future.
| arxiv topic:astro-ph.SR astro-ph.GA |
arxiv_dataset-38981212.0184 | Spectral and timing properties of the magnetar CXOU~J164710.2-455216
astro-ph.HE
We report on spectral and timing properties of the magnetar CXOU
J164710.2-455216 in the massive star cluster Westerlund 1. Using 11 archival
observations obtained with Chandra and XMM-Newton over approximately 1000 days
after the source's 2006 outburst, we study the flux and spectral evolution of
the source. We show that the hardness of the source, as quantified by hardness
ratio, blackbody temperature or power-law photon index, shows a clear
correlation with the 2--10 keV absorption-corrected flux and that the power-law
component flux decayed faster than the blackbody component for the first ~100
days. We also measure the timing properties of the source by analyzing data
spanning approximately 2500 days. The measured period and period derivative are
10.610644(17) s (MJD 53999.06) and <4 X 10^{-13} s s^-1 (90% confidence) which
imply that the spin-inferred dipolar magnetic field of the source is less than
7 X 10^{13} G. This is significantly smaller than was suggested previously. We
find evidence for a second flux increase, suggesting a second outburst between
MJDs 55068 and 55832. Finally, based on a crustal cooling model, we find that
the source's cooling curve can be reproduced if we assume that the energy was
deposited in the outer crust and that the temperature profile of the star right
after the 2006 outburst was relatively independent of density.
| arxiv topic:astro-ph.HE |
arxiv_dataset-38991212.0284 | Recent progress on the determination of the symmetry Energy
nucl-th astro-ph.SR nucl-ex
We summarize the current status on constraining the density dependence of the
symmetry energy from terrestrial laboratory measurements and astrophysical
observations. While the value $E_{sym}({\rho_{0}})$ and density slope $L$ of
the symmetry energy at saturation density $\rho_{0}$ can vary largely depending
on the data or methods, all the existing constraints are essentially consistent
with $E_{sym}({\rho_{0}}) = 31 \pm 2$ MeV and $L = 50 \pm 20$ MeV. The
determination of the supra-saturation density behavior of the symmetry energy
remains a big challenge.
| arxiv topic:nucl-th astro-ph.SR nucl-ex |
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