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arxiv_dataset-35001206.3907 | On the excess of ultra-high energy cosmic rays in the direction of
Centaurus A
astro-ph.HE
A posteriori anisotropy study of ultra-high energy cosmic rays (UHECRs) with
the Pierre Auger Observatory (PAO) has shown evidence of excess of cosmic ray
particles above 55 EeV within $18^{\circ}$ of the direction of the radio galaxy
Centaurus A. However, the origin of the excess remains elusive. We simulate the
propagation of different species of particles coming from the direction of
Centaurus A in the Galactic magnetic fields, and find that only particles of
nuclear charge $Z\la 10$ can avoid being deflected outside of the $18^{\circ}$
window of Centaurus A. On the other hand, considering the increasingly heavy
composition of UHECRs at the highest energies measured by PAO, a plausible
scenario for cosmic rays from the direction of Centaurus A can be found if they
consist of intermediate-mass nuclei. The chemical composition of cosmic rays
can be further constrained by lower-energy cosmic rays of the same rigidity. We
find that cosmic ray acceleration in the lobes of Centaurus A is not favored,
while acceleration in the stellar winds that are rich in intermediate-mass
nuclei, could meet the requirement. This suggests that the observed excess may
originate from cosmic ray accelerators induced by stellar explosions in the
star-forming regions of Centaurus A and/or the Centaurus cluster located behind
Centaurus A.
| arxiv topic:astro-ph.HE |
arxiv_dataset-35011206.4007 | Consecutive Sequential Probability Ratio Tests of Multiple Statistical
Hypotheses
math.ST math.PR stat.TH
In this paper, we develop a simple approach for testing multiple statistical
hypotheses based on the observations of a number of probability ratios
enumerated consecutively with respect to the index of hypotheses. Explicit and
tight bounds for the probability of making wrong decisions are obtained for
choosing appropriate parameters for the proposed tests. In the special case of
testing two hypotheses, our tests reduce to Wald's sequential probability ratio
tests.
| arxiv topic:math.ST math.PR stat.TH |
arxiv_dataset-35021206.4107 | Turyn-type sequences: Classification, Enumeration and Construction
math.CO
Turyn-type sequences, TT(n), are quadruples of {+,-1}-sequences (A;B;C;D),
with lengths n,n,n,n-1 respectively, where the sum of the nonperiodic
autocorrelation functions of A,B and twice that of C,D is a delta-function
(i.e., vanishes everywhere except at 0). Turyn-type sequences TT(n) are known
to exist for all even n not larger than 36. We introduce a definition of
equivalence to construct a canonical form for TT(n) in general. By using this
canonical form, we enumerate the equivalence classes of TT(n) for n up to and
including 32. We also construct the first example of Turyn-type sequences
TT(38).
| arxiv topic:math.CO |
arxiv_dataset-35031206.4207 | An introduction to d-manifolds and derived differential geometry
math.DG math.AG math.SG
This is a survey of the author's book "D-manifolds and d-orbifolds: a theory
of derived differential geometry", available at
http://people.maths.ox.ac.uk/~joyce/dmanifolds.html
We introduce a 2-category dMan of "d-manifolds", new geometric objects which
are 'derived' smooth manifolds, in the sense of the 'derived algebraic
geometry' of Toen and Lurie. They are a 2-category truncation of the 'derived
manifolds' of Spivak (see arXiv:0810.5174, arXiv:1212.1153). The category of
manifolds Man embeds in dMan as a full subcategory. We also define 2-categories
dMan^b,dMan^c of "d-manifolds with boundary" and "d-manifolds with corners",
and orbifold versions of these dOrb,dOrb^b,dOrb^c, "d-orbifolds". For brevity,
this survey concentrates mostly on d-manifolds without boundary. A longer and
more detailed summary of the book is given in arXiv:1208.4948.
Much of differential geometry extends very nicely to d-manifolds and
d-orbifolds -- immersions, submersions, submanifolds, transverse fibre
products, orientations, etc. Compact oriented d-manifolds and d-orbifolds have
virtual classes.
There are truncation functors to d-manifolds and d-orbifolds from essentially
every geometric structures on moduli spaces used in enumerative invariant
problems in differential geometry or complex algebraic geometry, including
Fredholm sections of Banach vector bundles over Banach manifolds, the
"Kuranishi spaces" of Fukaya, Oh, Ohta and Ono and the "polyfolds" of Hofer,
Wysocki and Zehnder in symplectic geometry, and C-schemes with perfect
obstruction theories in algebraic geometry. Thus, results in the literature
imply that many important classes of moduli spaces are d-manifolds or
d-orbifolds, including moduli spaces of J-holomorphic curves in symplectic
geometry.
D-manifolds and d-orbifolds will have applications in symplectic geometry,
and elsewhere.
| arxiv topic:math.DG math.AG math.SG |
arxiv_dataset-35041206.4307 | Parsec-scale dust emission from the polar region in the type 2 nucleus
of NGC 424
astro-ph.CO
Advancements in infrared IR open up the possibility to spatially resolve AGN
on the parsec-scale level and study the circumnuclear dust distribution,
commonly referred to as the "dust torus", that is held responsible for the type
1/type 2 dichotomy of AGN. We used the mid-IR beam combiner MIDI together with
the 8m telescopes at the VLTI to observe the nucleus of the Seyfert 2 galaxy
NGC 424, achieving an almost complete coverage of the uv-plane accessible by
the available telescope configurations. We detect extended mid-IR emission with
a relatively baseline- and model-independent mid-IR half-light radius of (2.0
\pm 0.2) pc \times (1.5 \pm 0.3) pc (averaged over the 8-13 {\mu}m wavelength
range). The extended mid-IR source shows an increasing size with wavelength.
The orientation of the major axis in position angle -27deg is closely aligned
with the system axis as set by optical polarization observations. Torus models
typically favor extension along the mid-plane at mid-IR wavelengths instead.
Therefore, we conclude that the majority of the pc-scale mid-IR emission
(>~60%) in this type 2 AGN originates from optically-thin dust in the polar
region of the AGN, a scenario consistent with the near- to far-IR SED. We
suggest that a radiatively-driven dusty wind, possibly launched in a puffed-up
region of the inner hot part of the torus, is responsible for the polar dust.
In this picture, the torus dominates the near-IR emission up to about 5 {\mu}m,
while the polar dust is the main contributor to the mid-IR flux. Our results of
NGC 424 are consistent with recent observations of the AGN in the Circinus
galaxy and resemble large-scale characteristics of other objects. If our
results reflect a general property of the AGN population, the current paradigm
for interpreting and modeling the IR emission of AGN have to be revised.
(abridged)
| arxiv topic:astro-ph.CO |
arxiv_dataset-35051206.4407 | Two-dimensional transition metal dichalcogenides under electron
irradiation: defect production and doping
cond-mat.mtrl-sci cond-mat.mes-hall
Using first-principles atomistic simulations, we study the response of
atomically-thin layers of transition metal dichalcogenides (TMDs) - a new class
of two-dimensional inorganic materials with unique electronic properties - to
electron irradiation. We calculate displacement threshold energies for atoms in
21 different compounds and estimate the corresponding electron energies
required to produce defects. For a representative structure of MoS2, we carry
out high-resolution transmission electron microscopy experiments and validate
our theoretical predictions via observations of vacancy formation under
exposure to a 80 keV electron beam. We further show that TMDs can be doped by
filling the vacancies created by the electron beam with impurity atoms.
Thereby, our results not only shed light on the radiation response of a system
with reduced dimensionality, but also suggest new ways for engineering the
electronic structure of TMDs.
| arxiv topic:cond-mat.mtrl-sci cond-mat.mes-hall |
arxiv_dataset-35061206.4507 | Controlling chemical reactions of a single particle
physics.atom-ph cond-mat.quant-gas quant-ph
The control of chemical reactions is a recurring theme in physics and
chemistry. Traditionally, chemical reactions have been investigated by tuning
thermodynamic parameters, such as temperature or pressure. More recently,
physical methods such as laser or magnetic field control have emerged to
provide completely new experimental possibilities, in particular in the realm
of cold collisions. The control of reaction pathways is also a critical
component to implement molecular quantum information processing. For these
undertakings, single particles provide a clean and well-controlled experimental
system. Here, we report on the experimental tuning of the exchange reaction
rates of a single trapped ion with ultracold neutral atoms by exerting control
over both their quantum states. We observe the influence of the hyperfine
interaction on chemical reaction rates and branching ratios, and monitor the
kinematics of the reaction products. These investigations advance chemistry
with single trapped particles towards achieving quantum-limited control of
chemical reactions and indicate limits for buffer gas cooling of single ion
clocks.
| arxiv topic:physics.atom-ph cond-mat.quant-gas quant-ph |
arxiv_dataset-35071206.4607 | Distributed Tree Kernels
cs.LG stat.ML
In this paper, we propose the distributed tree kernels (DTK) as a novel
method to reduce time and space complexity of tree kernels. Using a linear
complexity algorithm to compute vectors for trees, we embed feature spaces of
tree fragments in low-dimensional spaces where the kernel computation is
directly done with dot product. We show that DTKs are faster, correlate with
tree kernels, and obtain a statistically similar performance in two natural
language processing tasks.
| arxiv topic:cs.LG stat.ML |
arxiv_dataset-35081206.4707 | Prime ends rotation numbers and periodic points
math.DS
We study the problem of existence of a periodic point in the boundary of an
invariant domain for a surface homeomorphism. In the area-preserving setting, a
complete classification is given in terms of rationality of Carath\'eordory's
prime ends rotation number, similar to Poincar\'e's theory for circle
homeomorphisms. In particular, we prove the converse of a classic result of
Cartwright and Littlewood. This has a number of consequences for generic area
preserving surface diffeomorphisms. For instance, we extend previous results of
J. Mather on the boundary of invariant open sets for $C^r$-generic area
preserving diffeomorphisms. Most results are proved in a general context, for
homeomorphisms of arbitrary surfaces with a weak nonwandering-type hypothesis.
This allows us to prove a conjecture of R. Walker about co-basin boundaries,
and it also has applications in holomorphic dynamics.
| arxiv topic:math.DS |
arxiv_dataset-35091206.4807 | Distances between Poisson k-flats
math.PR math.MG
The distances between flats of a Poisson $k$-flat process in the
$d$-dimensional Euclidean space with $k<d/2$ are discussed. Continuing an
approach originally due to Rolf Schneider, the number of pairs of flats having
distance less than a given threshold and midpoint in a fixed compact and convex
set is considered. For a family of increasing convex subsets, the asymptotic
variance is computed and a central limit theorem with an explicit rate of
convergence is proven. Moreover, the asymptotic distribution of the $m$-th
smallest distance between two flats is investigated and it is shown that the
ordered distances form asymptotically after suitable rescaling an inhomogeneous
Poisson point process on the positive real axis. A similar result with a
homogeneous limiting process is derived for distances around a fixed, strictly
positive value. Our proofs rely on recent findings based on the Wiener-It\^o
chaos decomposition and the Malliavin-Stein method.
| arxiv topic:math.PR math.MG |
arxiv_dataset-35101206.4907 | Mean-Field Gauge Interactions in Five Dimensions II. The Orbifold
hep-lat
We study Gauge-Higgs Unification in five dimensions on the lattice by means
of the mean-field expansion. We formulate it for the case of an SU(2) pure
gauge theory and orbifold boundary conditions along the extra dimension, which
explicitly break the gauge symmetry to U(1) on the boundaries. Our main result
is that the gauge boson mass computed from the static potential along
four-dimensional hyperplanes is nonzero implying spontaneous symmetry breaking.
This observation supports earlier data from Monte Carlo simulations [12].
| arxiv topic:hep-lat |
arxiv_dataset-35111206.5007 | Detecting the Rise and Fall of the First Stars by Their Impact on Cosmic
Reionization
astro-ph.CO
The intergalactic medium was reionized before redshift z~6, most likely by
starlight which escaped from early galaxies. The very first stars formed when
hydrogen molecules (H2) cooled gas inside the smallest galaxies, minihalos of
mass between 10^5 and 10^8 solar masses. Although the very first stars began
forming inside these minihalos before redshift z~40, their contribution has, to
date, been ignored in large-scale simulations of this cosmic reionization. Here
we report results from the first reionization simulations to include these
first stars and the radiative feedback that limited their formation, in a
volume large enough to follow the crucial spatial variations that influenced
the process and its observability. We show that, while minihalo stars stopped
far short of fully ionizing the universe, reionization began much earlier with
minihalo sources than without, and was greatly extended, which boosts the
intergalactic electron-scattering optical depth and the large-angle
polarization fluctuations of the cosmic microwave background significantly.
Although within current WMAP uncertainties, this boost should be readily
detectable by Planck. If reionization ended as late as z_ov<~7, as suggested by
other observations, Planck will thereby see the signature of the first stars at
high redshift, currently undetectable by other probes.
| arxiv topic:astro-ph.CO |
arxiv_dataset-35121206.5107 | Electron-phonon bound states in graphene in a perpendicular magnetic
field
cond-mat.mes-hall
The spectrum of electron-phonon complexes in a monolayer graphene is
investigated in the presence of a perpendicular quantizing magnetic field.
Despite the small electron-phonon coupling, usual perturbation theory is
inapplicable for calculation of the scattering amplitude near the threshold of
the optical phonon emission. Our findings beyond perturbation theory show that
the true spectrum near the phonon emission threshold is completely governed by
new branches, corresponding to bound states of an electron and an optical
phonon with a binding energy of the order of $\alpha \omega_{0}$ where $\alpha$
is the electron-phonon coupling and $\omega_{0}$ the phonon energy.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-35131206.5207 | Titan's transport-driven methane cycle
astro-ph.EP
The strength of Titan's methane cycle, as measured by precipitation and
evaporation, is key to interpreting fluvial erosion and other indicators of the
surface-atmosphere exchange of liquids. But the mechanisms behind the
occurrence of large cloud outbursts and precipitation on Titan have been
disputed. A gobal- and annual-mean estimate of surface fluxes indicated only 1%
of the insolation, or $\sim$0.04 W/m$^2$, is exchanged as sensible and/or
latent fluxes. Since these fluxes are responsible for driving atmospheric
convection, it has been argued that moist convection should be quite rare and
precipitation even rarer, even if evaporation globally dominates the
surface-atmosphere energy exchange. In contrast, climate simulations that allow
atmospheric motion indicate a robust methane cycle with substantial cloud
formation and/or precipitation. We argue the top-of-atmosphere radiative
imbalance -- a readily observable quantity -- is diagnostic of horizontal heat
transport by Titan's atmosphere, and thus constrains the strength of the
methane cycle. Simple calculations show the top-of-atmosphere radiative
imbalance is $\sim$0.5-1 W/m$^2$ in Titan's equatorial region, which implies
2-3 MW of latitudinal heat transport by the atmosphere. Our simulation of
Titan's climate suggests this transport may occur primarily as latent heat,
with net evaporation at the equator and net accumulation at higher latitudes.
Thus the methane cycle could be 10-20 times previous estimates. Opposing
seasonal transport at solstices, compensation by sensible heat transport, and
focusing of precipitation by large-scale dynamics could further enhance the
local, instantaneous strength of Titan's methane cycle by a factor of several.
| arxiv topic:astro-ph.EP |
arxiv_dataset-35141206.5307 | A hot Uranus transiting the nearby M dwarf GJ3470. Detected with HARPS
velocimetry. Captured in transit with TRAPPIST photometry
astro-ph.EP
We report on the discovery of GJ3470b, a transiting hot Uranus of mass m_p =
14.0+-1.8 Mearth, radius R_p = 4.2+-0.6 Rearth and period P=3.3371+-0.0002 day.
Its host star is a nearby (d=25.2+-2.9pc) M1.5 dwarf of mass M_s=0.54+-0.07
Msol and radius R_s=0.50+-0.06 Rsol. The detection originates from a
radial-velocity campaign with HARPS that focused on the search for short-period
planets orbiting M dwarfs. Once the planet was discovered and the
transit-search window narrowed to about 10% of an orbital period, a photometric
search started with TRAPPIST and quickly detected the ingress of the planet.
Additional observations with TRAPPIST, EulerCam and NITES definitely confirmed
the transiting nature of GJ3470b and allow for the determination of its true
mass and radius. The star's visible or infrared brightness (V=12.3, K=8.0 mag),
together with a large eclipse depth D=0.57+-0.05%, ranks GJ3470b among the most
favorable planets for follow-up characterizations.
| arxiv topic:astro-ph.EP |
arxiv_dataset-35151206.5407 | Modeling quantum noise for efficient testing of fault-tolerant circuits
quant-ph
Understanding fault-tolerant properties of quantum circuits is important for
the design of large-scale quantum information processors. In particular,
simulating properties of encoded circuits is a crucial tool for investigating
the relationships between the noise model, encoding scheme, and threshold
value. For general circuits and noise models, these simulations quickly become
intractable in the size of the encoded circuit. We introduce methods for
approximating a noise process by one which allows for efficient Monte Carlo
simulation of properties of encoded circuits. The approximations are as close
to the original process as possible without overestimating their ability to
preserve quantum information, a key property for obtaining more honest
estimates of threshold values. We numerically illustrate the method with
various physically relevant noise models.
| arxiv topic:quant-ph |
arxiv_dataset-35161206.5507 | Cosmological pseudobulge formation
astro-ph.CO astro-ph.GA
Bulges can be classified into classical and pseudobulges; the former are
considered to be end products of galactic mergers and the latter to form via
secular evolution of galactic disks. Observationally, bulges of disk galaxies
are mostly pseudobulges, including the Milky Way's. We here show, by using
self-consistent cosmological simulations of galaxy formation, that the
formation of pseudobulges of Milky Way-sized disk galaxies has mostly completed
before disk formation; thus the main channel of pseudobulge formation is not
secular evolution of disks. Our pseudobulges form by rapid gas supply at
high-redshift and their progenitors would be observed as high-redshift disks.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-35171206.5607 | Phase transitions in strongly coupled 3d Z(N) lattice gauge theories at
finite temperature
hep-lat cond-mat.stat-mech
We perform an analytical and numerical study of the phase transitions in
three-dimensional Z(N) lattice gauge theories at finite temperature for N>4
exploiting equivalence of these models with a generalized version of the
two-dimensional vector Potts models in the limit of vanishing spatial coupling.
In this limit the Polyakov loops play the role of Z(N) spins. The effective
couplings of these two-dimensional spin models are calculated explicitly. It is
argued that the effective spin models have two phase transitions of BKT type.
This is confirmed by large-scale Monte Carlo simulations. Using a cluster
algorithm we locate the position of the critical points and study the critical
behavior across both phase transitions in details. In particular, we determine
various critical indices, compute the helicity modulus, the average action and
the specific heat. A scaling formula for the critical points with N is
proposed.
| arxiv topic:hep-lat cond-mat.stat-mech |
arxiv_dataset-35181206.5707 | More on the Frattini Subalgebra of a Leibniz Algebra
math.RA
We study the Frattini subalgebra of Leibniz algebras generated by one
element. We also investigate Leibniz algebras all of whose proper subalgebras
are elementary.
| arxiv topic:math.RA |
arxiv_dataset-35191206.5807 | The Zurich Environmental Study (ZENS) of Galaxies in Groups along the
Cosmic Web. I. Which Environment Affects Galaxy Evolution?
astro-ph.CO
The Zurich Environmental Study (ZENS) is based on a sample of ~1500 galaxy
members of 141 groups in the mass range ~10^12.5-14.5 M_sun within the narrow
redshift range 0.05<z<0.0585. ZENS adopts novel approaches, here described, to
quantify four different galactic environments, namely: (1) the mass of the host
group halo; (2) the projected halo-centric distance; (3) the rank of galaxies
as central or satellites within their group halos; and (4) the filamentary
large-scale structure (LSS) density. No self-consistent identification of a
central galaxy is found in ~40% of <10^13.5 M_sun groups, from which we
estimate that ~15% of groups at these masses are dynamically unrelaxed systems.
Central galaxies in relaxed and unrelaxed groups have in general similar
properties, suggesting that centrals are regulated by their mass and not by
their environment. Centrals in relaxed groups have however ~30% larger sizes
than in unrelaxed groups, possibly due accretion of small satellites in
virialized group halos. At M>10^10 M_sun, satellite galaxies in relaxed and
unrelaxed groups have similar size, color and (specific) star formation rate
distributions; at lower galaxy masses, satellites are marginally redder in
relaxed relative to unrelaxed groups, suggesting quenching of star formation in
low-mass satellites by physical processes active in relaxed halos. Finally,
relaxed and unrelated groups show similar stellar mass conversion efficiencies,
peaking at halo masses around 10^12.5 M_sun. In the enclosed ZENS catalogue we
publish all environmental diagnostics as well as the galaxy structural and
photometric measurements described in companion ZENS papers II and III.
| arxiv topic:astro-ph.CO |
arxiv_dataset-35201206.5907 | Notes on generalizations of local Ogus-Vologodsky correspondence
math.NT math.AG
Given a smooth scheme over $\Z/p^n\Z$ with a lift of relative Frobenius to
$\Z/p^{n+1}\Z$, we construct a functor from the category of Higgs modules to
that of modules with integrable connections as the composite of the level
raising inverse image functors from the category of modules with integrable
$p^{m}$-connections to that of modules with integrable $p^{m-1}$-connections
for $1 \leq m \leq n$. In the case $m=1$, we prove that the level raising
inverse image functor is an equivalence when restricted to quasi-nilpotent
objects, which generalizes a local result of Ogus-Vologodsky. We also prove
that the above level raising inverse image functor for a smooth $p$-adic formal
scheme induces an equivalence of $\Q$-linearized categories for general $m$
when restricted to nilpotent objects (in strong sense), under a strong
condition on Frobenius lift. We also prove a similar result for the category of
modules with integrable $p^{m}$-Witt-connections.
| arxiv topic:math.NT math.AG |
arxiv_dataset-35211206.6007 | "Cooling by heating" - demonstrating the significance of the
longitudinal specific heat
cond-mat.soft
Heating a solid sphere at the surface induces mechanical stresses inside the
sphere. If a finite amount of heat is supplied, the stresses gradually
disappear as temperature becomes homogeneous throughout the sphere. We show
that before this happens, there is a temporary lowering of pressure and density
in the interior of the sphere, inducing a transient lowering of the temperature
here. For ordinary solids this effect is small because c_p is almost equal to
c_V. For fluent liquids the effect is negligible because their dynamic shear
modulus vanishes. For a liquid at its glass transition, however, the effect is
generally considerably larger than in solids. This paper presents analytical
solutions of the relevant coupled thermoviscoelastic equations. In general,
there is a difference between the isobaric specific heat, c_p, measured at
constant isotropic pressure and the longitudinal specific heat, c_l, pertaining
to mechanical boundary conditions that confine the associated expansion to be
longitudinal. In the exact treatment of heat propagation the heat diffusion
constant contains c_l rather than c_p. We show that the key parameter
controlling the magnitude of the "cooling-by-heating" effect is the relative
difference between these two specific heats. For a typical glass-forming
liquid, when temperature at the surface is increased by 1 K, a lowering of the
temperature in the sphere center of order 5 mK is expected if the experiment is
performed at the glass transition. The cooling-by-heating effect is confirmed
by measurements on a 19 mm diameter glucose sphere at the glass transition.
| arxiv topic:cond-mat.soft |
arxiv_dataset-35221206.6107 | An Empirical Relation between Sodium Absorption and Dust Extinction
astro-ph.IM astro-ph.CO astro-ph.GA
Dust extinction and reddening are ubiquitous in astronomical observations and
are often a major source of systematic uncertainty. We present here a study of
the correlation between extinction in the Milky Way and the equivalent width of
the NaI D absorption doublet. Our sample includes more than 100 high resolution
spectra from the KECK telescopes and nearly a million low resolution spectra
from the Sloan Digital Sky Survey (SDSS). We measure the correlation to
unprecedented precision, constrain its shape, and derive an empirical relation
between these quantities with a dispersion of order 0.15 magnitude in E(B-V).
From the shape of the curve of growth we further show that a typical sight line
through the Galaxy, as seen within the SDSS footprint, crosses about three dust
clouds. We provide a brief guide on how to best estimate extinction to
extragalactic sources such as supernovae, using the NaI D absorption feature,
under a variety of circumstances.
| arxiv topic:astro-ph.IM astro-ph.CO astro-ph.GA |
arxiv_dataset-35231206.6207 | An Optimal Fully Distributed Algorithm to Minimize the Resource
Consumption of Cloud Applications
cs.DC
According to the pay-per-use model adopted in clouds, the more the resources
consumed by an application running in a cloud computing environment, the
greater the amount of money the owner of the corresponding application will be
charged. Therefore, applying intelligent solutions to minimize the resource
consumption is of great importance. Because centralized solutions are deemed
unsuitable for large-distributed systems or large-scale applications, we
propose a fully distributed algorithm (called DRA) to overcome the scalability
issues. Specifically, DRA migrates the inter-communicating components of an
application, such as processes or virtual machines, close to each other to
minimize the total resource consumption. The migration decisions are made in a
dynamic way and based only on local information. We prove that DRA achieves
convergence and results always in the optimal solution.
| arxiv topic:cs.DC |
arxiv_dataset-35241206.6307 | On sets of finite perimeter in Wiener spaces: reduced boundary and
convergence to halfspaces
math.CA
We study sets of finite perimeter in Wiener space, and prove that at almost
every point (with respect to the perimeter measure) a set of finite perimeter
blows-up to a halfspace.
| arxiv topic:math.CA |
arxiv_dataset-35251206.6407 | Large-Scale Feature Learning With Spike-and-Slab Sparse Coding
cs.LG stat.ML
We consider the problem of object recognition with a large number of classes.
In order to overcome the low amount of labeled examples available in this
setting, we introduce a new feature learning and extraction procedure based on
a factor model we call spike-and-slab sparse coding (S3C). Prior work on S3C
has not prioritized the ability to exploit parallel architectures and scale S3C
to the enormous problem sizes needed for object recognition. We present a novel
inference procedure for appropriate for use with GPUs which allows us to
dramatically increase both the training set size and the amount of latent
factors that S3C may be trained with. We demonstrate that this approach
improves upon the supervised learning capabilities of both sparse coding and
the spike-and-slab Restricted Boltzmann Machine (ssRBM) on the CIFAR-10
dataset. We use the CIFAR-100 dataset to demonstrate that our method scales to
large numbers of classes better than previous methods. Finally, we use our
method to win the NIPS 2011 Workshop on Challenges In Learning Hierarchical
Models? Transfer Learning Challenge.
| arxiv topic:cs.LG stat.ML |
arxiv_dataset-35261206.6507 | Correlation functions for Schr\"odinger backgrounds
hep-th
We work out the holographic dictionary for the three-dimensional
Schr\"odinger spacetimes. The first step in our analysis involves the correct
identification of the dual sources from the radial expansion of the bulk
fields, which turns out to be surprisingly subtle. We discuss in detail the
holographic renormalization procedure at the linearized level and
holographically compute the two-point functions of the energy-momentum tensor
and an irrelevant vector operator. We discuss the appearance of multi-trace
counterterms, parametrize the scheme dependence in our results, identify the
non-relativistic Ward identities and compare them with expectations in the
literature. Our results lead to valuable general insights regarding holography
for spacetimes that are not of an asymptotically AdS form.
| arxiv topic:hep-th |
arxiv_dataset-35271206.6607 | Divisibility Relations for the Dimensions and Hilbert series of Nichols
Algebras of Non-Abelian Group Type
math.QA
We present a divisibility relation for the dimensions and Hilbert series of
certain classes of Nichols algebras of non-abelian group type, which
generalizes Nichols algebras over Coxeter groups with constant cocycle -1. For
this we introduce three groups of isomorphisms acting on Nichols algebras,
which generalize the exchange operator introduced by Milinski and Schneider for
Coxeter groups in "Pointed indecomposable Hopf algebras over Coxeter groups".
| arxiv topic:math.QA |
arxiv_dataset-35281206.6707 | Optical conductivity study of screening of many-body effects in graphene
interfaces
cond-mat.mes-hall cond-mat.str-el
Theoretical studies have shown that electron-electron (e-e) and electron-hole
(e-h) interactions play important roles in many observed quantum properties of
graphene making this an ideal system to study many body effects. In this report
we show that spectroscopic ellipsometry can enable us to measure this
interactions quantitatively. We present spectroscopic data in two extreme
systems of graphene on quartz (GOQ), an insulator, and graphene on copper
(GOC), a metal which show that for GOQ, both e-e and e-h interactions dominate
while for GOC e-h interactions are screened. The data further enables the
estimation of the strength of the many body interaction through the effective
fine structure constant, $\alpha_{g}^{*}$. The $\alpha_{g}^{*}$ for GOQ
indicates a strong correlation with an almost energy independent value of about
1.37. In contrast, $\alpha_{g}^{*}$ value of GOC is photon energy dependent, is
almost two orders of magnitude lower at low energies indicating very weak
correlation.
| arxiv topic:cond-mat.mes-hall cond-mat.str-el |
arxiv_dataset-35291206.6807 | The influence of jet geometry on light curves and spectra of GRB
afterglows
astro-ph.HE
We have performed detailed calculations of spectra and light curves of GRB
afterglows assuming that the observed GRBs can have a jet geometry. The
calculations are based on an expanding relativistic shock GRB afterglow model
where the afterglow is the result of synchrotron radiation of relativistic
electrons with power-law energy distribution at the front of external shock
being decelerated in a circumstellar medium. To determine the intensity on the
radiation surface we solve numerically the full time-, angle-, and
frequency-dependent special relativistic transfer equation in the comoving
frame using the method of long characteristics.
| arxiv topic:astro-ph.HE |
arxiv_dataset-35301206.6907 | K-orbit closures on G/B as universal degeneracy loci for flagged vector
bundles with symmetric or skew-symmetric bilinear form
math.AG math.AT math.RT
We use equivariant localization and divided difference operators to determine
formulas for the torus-equivariant fundamental cohomology classes of $K$-orbit
closures on the flag variety $G/B$, where $G = GL(n,\C)$, and where $K$ is one
of the symmetric subgroups $O(n,\C)$ or $Sp(n,\C)$. We realize these orbit
closures as universal degeneracy loci for a vector bundle over a variety
equipped with a single flag of subbundles and a nondegenerate symmetric or
skew-symmetric bilinear form taking values in the trivial bundle. We describe
how our equivariant formulas can be interpreted as giving formulas for the
classes of such loci in terms of the Chern classes of the various bundles.
| arxiv topic:math.AG math.AT math.RT |
arxiv_dataset-35311206.7007 | Inclusive Deep Inelastic Scattering at High Q2 with Longitudinally
Polarised Lepton Beams at HERA
hep-ex
Inclusive e\pmp single and double differential cross sections for neutral and
charged current deep inelastic scattering processes are measured with the H1
detector at HERA. The data were taken at a centre-of-mass energy of \surds =
319GeV with a total integrated luminosity of 333.7 pb-1 shared between two
lepton beam charges and two longitudinal lepton polarisation modes. The
differential cross sections are measured in the range of negative fourmomentum
transfer squared, Q2, between 60 and 50 000GeV2, and Bjorken x between 0.0008
and 0.65. The measurements are combined with earlier published unpolarised H1
data to improve statistical precision and used to determine the structure
function xF_3^gammaZ. A measurement of the neutral current parity violating
structure function F_2^gammaZ is presented for the first time. The polarisation
dependence of the charged current total cross section is also measured. The new
measurements are well described by a next-to-leading order QCD fit based on all
published H1 inclusive cross section data which are used to extract the parton
distribution functions of the proton.
| arxiv topic:hep-ex |
arxiv_dataset-35321206.7107 | Radius of a Photon Beam with Orbital Angular Momentum
physics.optics
We analyze the transverse structure of the Gouy phase shift in light beams
carrying orbital angular momentum and show that the Gouy radius $r_G$
characterizing the transverse structure grows as $\sqrt{2p+|\ell|+1}$ with the
nodal number $p$ and photon angular momentum number $\ell$. The Gouy radius is
shown to be closely related to the root-mean-square radius of the beam, and the
divergence of the radius away from the focal plane is determined. Finally, we
analyze the rotation of the Poynting vector in the context of the Gouy radius.
| arxiv topic:physics.optics |
arxiv_dataset-35331207.0086 | Semispectral Measures and Feller markov Kernels
math.FA
We give a characterization of commutative semispectral measures by means of
Feller and Strong Feller Markov kernels. In particular:
{itemize} we show that a semispectral measure $F$ is commutative if and only
if there exist a self-adjoint operator $A$ and a Markov kernel
$\mu_{(\cdot)}(\cdot):\Gamma\times\mathcal{B}(\mathbb{R})\to[0,1]$,
$\Gamma\subset\sigma(A)$, $E(\Gamma)=\mathbf{1}$, such that
$$F(\Delta)=\int_{\Gamma}\mu_{\Delta}(\lambda)\,dE_{\lambda},$$ \noindent and
$\mu_{(\Delta)}$ is continuous for each $\Delta\in R$ where,
$R\subset\mathcal{B}(\mathbb{R})$ is a ring which generates the Borel
$\sigma$-algebra of the reals $\mathcal{B}(\mathbb{R})$. Moreover,
$\mu_{(\cdot)}(\cdot)$ is a Feller Markov kernel and separates the points of
$\Gamma$. we prove that $F$ admits a strong Feller Markov kernel
$\mu_{(\cdot)}(\cdot)$, if and only if $F$ is uniformly continuous. Finally, we
prove that if $F$ is absolutely continuous with respect to a regular finite
measure $\nu$ then, it admits a strong Feller Markov kernel. {itemize} The
mathematical and physical relevance of the results is discussed giving a
particular emphasis to the connections between $\mu$ and the imprecision of the
measurement apparatus.
| arxiv topic:math.FA |
arxiv_dataset-35341207.0186 | Single-valued harmonic polylogarithms and the multi-Regge limit
hep-th hep-ph
We argue that the natural functions for describing the multi-Regge limit of
six-gluon scattering in planar N=4 super Yang-Mills theory are the
single-valued harmonic polylogarithmic functions introduced by Brown. These
functions depend on a single complex variable and its conjugate, (w,w*). Using
these functions, and formulas due to Fadin, Lipatov and Prygarin, we determine
the six-gluon MHV remainder function in the leading-logarithmic approximation
(LLA) in this limit through ten loops, and the next-to-LLA (NLLA) terms through
nine loops. In separate work, we have determined the symbol of the four-loop
remainder function for general kinematics, up to 113 constants. Taking its
multi-Regge limit and matching to our four-loop LLA and NLLA results, we fix
all but one of the constants that survive in this limit. The multi-Regge limit
factorizes in the variables (\nu,n) which are related to (w,w*) by a
Fourier-Mellin transform. We can transform the single-valued harmonic
polylogarithms to functions of (\nu,n) that incorporate harmonic sums,
systematically through transcendental weight six. Combining this information
with the four-loop results, we determine the eigenvalues of the BFKL kernel in
the adjoint representation to NNLLA accuracy, and the MHV product of impact
factors to NNNLLA accuracy, up to constants representing beyond-the-symbol
terms and the one symbol-level constant. Remarkably, only derivatives of the
polygamma function enter these results. Finally, the LLA approximation to the
six-gluon NMHV amplitude is evaluated through ten loops.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-35351207.0286 | Type-II Bose-Mott insulators
cond-mat.str-el cond-mat.supr-con
The Mott insulating state formed from bosons is ubiquitous in solid He-4,
cold atom systems, Josephson junction networks and perhaps underdoped high-Tc
superconductors. We predict that close to the quantum phase transition to the
superconducting state the Mott insulator is not at all as featureless as is
commonly believed. In three dimensions there is a phase transition to a low
temperature state where, under influence of an external current, a
superconducting state consisting of a regular array of 'wires' that each carry
a quantized flux of supercurrent is realized. This prediction of the "type-II
Mott insulator" follows from a field theoretical weak-strong duality, showing
that this 'current lattice' is the dual of the famous Abrikosov lattice of
magnetic fluxes in normal superconductors. We argue that this can be exploited
to investigate experimentally whether preformed Cooper pairs exist in high-Tc
superconductors.
| arxiv topic:cond-mat.str-el cond-mat.supr-con |
arxiv_dataset-35361207.0386 | Vortex-Bright Soliton Dipoles: Bifurcations, Symmetry Breaking and
Soliton Tunneling in a Vortex-Induced Double Well
cond-mat.quant-gas nlin.PS
The emergence of vortex-bright soliton dipoles in two-component Bose-Einstein
condensates through bifurcations from suitable eigenstates of the underlying
linear system is examined. These dipoles can have their bright solitary
structures be in phase (symmetric) or out of phase (anti-symmetric). The
dynamical robustness of each of these two possibilities is considered and the
out-of-phase case is found to exhibit an intriguing symmetry-breaking
instability that can in turn lead to tunneling of the bright wavefunction
between the two vortex "wells". We interpret this phenomenon by virtue of a
vortex-induced double well system, whose spontaneous symmetry breaking leads to
asymmetric vortex-bright dipoles, in addition to the symmetric and
anti-symmetric ones. The theoretical prediction of these states is corroborated
by detailed numerical computations.
| arxiv topic:cond-mat.quant-gas nlin.PS |
arxiv_dataset-35371207.0486 | Wind driven 3D Navier-Stokes circulation in the Atlantic
math.NA
A finite element method for the numerical solution of the anisotropic
Navier-Stokes equations in shallow domain is presented. This method take into
account aspect ratio in the hydrostatic approximation of the Navier-Stokes
equations \cite{beslay,azthese,azgui}. A projection method \cite{guermond,shen}
is used for the time discretization. The linear systems are solved via a some
preconditioned conjugate algorithm, well adapted to massively parallel
computers \cite{julien_these,julien_precond,julien_precond_paral}. Some results
are presented for the wind driven water circulation in the North Atlantic.
| arxiv topic:math.NA |
arxiv_dataset-35381207.0586 | Fast shape reconstruction of perfectly conducting cracks by using a
multi-frequency topological derivative strategy
math-ph math.MP
This paper concerns a fast, one-step iterative technique of imaging extended
perfectly conducting cracks with Dirichlet boundary condition. In order to
reconstruct the shape of cracks from scattered field data measured at the
boundary, we introduce a topological derivative-based electromagnetic imaging
function operated at several nonzero frequencies. The properties of the imaging
function are carefully analyzed for the configurations of both symmetric and
non-symmetric incident field directions. This analysis explains why the
application of incident fields with symmetric direction operated at multiple
frequencies guarantees a successful reconstruction. Various numerical
simulations with noise-corrupted data are conducted to assess the performance,
effectiveness, robustness, and limitations of the proposed technique.
| arxiv topic:math-ph math.MP |
arxiv_dataset-35391207.0686 | Fermionic Wigs for AdS-Schwarzschild Black Holes
hep-th gr-qc
We provide the metric, the gravitino fields and the gauge fields to all
orders in the fermionic zero modes for D=5 and D=4, N=2 gauged supergravity
solutions starting from non-extremal AdS--Schwarzschild black holes. We compute
the Brown-York stress--energy tensor on the boundary of AdS_5 / AdS_4 spaces
and we discuss some implications of the fermionic corrections to perfect fluid
interpretation of the boundary theory. The complete non-linear solution, which
we denote as fermionic wig, is achieved by acting with supersymmetry
transformations upon the supergravity fields and that expansion naturally
truncates at some order in the fermionic zero modes.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-35401207.0786 | A combinatorial formula for fusion coefficient
math.CO math.QA
Using the expansion of the inverse of the Kostka matrix in terms of tabloids
as presented by Egecioglu and Remmel, we show that the fusion coefficients can
be expressed as an alternating sum over cylindric tableaux. Cylindric tableaux
are skew tableaux with a certain cyclic symmetry. When the skew shape of the
tableau has a cutting point, meaning that the cylindric skew shape is not
connected, or if its weight has at most two parts, we give a positive
combinatorial formula for the fusion coefficients. The proof uses a slight
modification of a sign-reversing involution introduced by Remmel and Shimozono.
We discuss how this approach may work in general.
| arxiv topic:math.CO math.QA |
arxiv_dataset-35411207.0886 | Emergent Space and the Example of AdS_5XS^5
hep-th
We explain how to build field theoretic observables from which the
geometrical properties of a dual holographic formulation can be read off
straightforwardly. In some cases this construction yields explicit and
calculable models of emergent space. We illustrate the idea on the type IIB
background generated by N D3-branes in the near horizon limit, for which a full
derivation from first principles can be presented. The six transverse
dimensions emerge at large N and we find the full AdS_5XS^5 metric and
self-dual Ramond-Ramond field strength on the resulting ten dimensional
space-time, with the correct radii and quantization law. We briefly discuss
possible applications and generalizations.
| arxiv topic:hep-th |
arxiv_dataset-35421207.0986 | Reexamining the "finite-size" effects in isobaric yield ratios using a
statistical abrasion-ablation model
nucl-th nucl-ex
The "finite-size" effects in the isobaric yield ratio (IYR), which are shown
in the standard grand-canonical and canonical statistical ensembles (SGC/CSE)
method, is claimed to prevent obtaining the actual values of physical
parameters. The conclusion of SGC/CSE maybe questionable for neutron-rich
nucleus induced reaction. To investigate whether the IYR has "finite-size"
effects, the IYR for the mirror nuclei [IYR(m)] are reexamined using a modified
statistical abrasion-ablation (SAA) model. It is found when the projectile is
not so neutron-rich, the IYR(m) depends on the isospin of projectile, but the
size dependence can not be excluded. In reactions induced by the very
neutron-rich projectiles, contrary results to those of the SGC/CSE models are
obtained, i.e., the dependence of the IYR(m) on the size and the isospin of the
projectile is weakened and disappears both in the SAA and the experimental
results.
| arxiv topic:nucl-th nucl-ex |
arxiv_dataset-35431207.1086 | Realistic fluids as source for dynamically accreting black holes in a
cosmological background
gr-qc astro-ph.CO
We show that a single imperfect fluid can be used as a source to obtain the
generalized McVittie metric as an exact solution to Einstein's equations. The
mass parameter in this metric varies with time thanks to a mechanism based on
the presence of a temperature gradient. This fully dynamical solution is
interpreted as an accreting black hole in an expanding universe if the metric
asymptotes to Schwarzschild-de Sitter at temporal infinity. We present a simple
but instructive example for the mass function and briefly discuss the structure
of the apparent horizons and the past singularity.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-35441207.1186 | Periodic and Quasiperiodic Motion of an Elongated Microswimmer in
Poiseuille Flow
cond-mat.soft physics.bio-ph physics.flu-dyn
We study the dynamics of a prolate spheroidal microswimmer in Poiseuille flow
for different flow geometries. When moving between two parallel plates or in a
cylindrical microchannel, the swimmer performs either periodic swinging or
periodic tumbling motion. Although the trajectories of spherical and elongated
swimmers are qualitatively similar, the swinging and tumbling frequency
strongly depends on the aspect ratio of the swimmer. In channels with reduced
symmetry the swimmers perform quasiperiodic motion which we demonstrate
explicitely for swimming in a channel with elliptical cross section.
| arxiv topic:cond-mat.soft physics.bio-ph physics.flu-dyn |
arxiv_dataset-35451207.1286 | Do stochastic inhomogeneities affect dark-energy precision measurements?
astro-ph.CO gr-qc hep-th
The effect of a stochastic background of cosmological perturbations on the
luminosity-redshift relation is computed to second order through a recently
proposed covariant and gauge-invariant light-cone averaging procedure. The
resulting expressions are free from both ultraviolet and infrared divergences,
implying that such perturbations cannot mimic a sizable fraction of dark
energy. Different averages are estimated and depend on the particular function
of the luminosity distance being averaged. The energy flux, being minimally
affected by perturbations at large z, is proposed as the best choice for
precision estimates of dark-energy parameters. Nonetheless, its irreducible
(stochastic) variance induces statistical errors on \Omega_{\Lambda}(z)
typically lying in the few-percent range.
| arxiv topic:astro-ph.CO gr-qc hep-th |
arxiv_dataset-35461207.1386 | Metrics for Markov Decision Processes with Infinite State Spaces
cs.AI
We present metrics for measuring state similarity in Markov decision
processes (MDPs) with infinitely many states, including MDPs with continuous
state spaces. Such metrics provide a stable quantitative analogue of the notion
of bisimulation for MDPs, and are suitable for use in MDP approximation. We
show that the optimal value function associated with a discounted infinite
horizon planning task varies continuously with respect to our metric distances.
| arxiv topic:cs.AI |
arxiv_dataset-35471207.1486 | Cross Sections from 800 MeV Proton Irradiation of Terbium
nucl-ex nucl-th
A single terbium foil was irradiated with 800 MeV protons to ascertain the
potential for production of lanthanide isotopes of interest in medical,
astrophysical, and basic science research and to contribute to nuclear data
repositories. Isotopes produced in the foil were quantified by gamma
spectroscopy. Cross sections for 36 isotopes produced in the irradiation are
reported and compared with predictions by the MCNP6 transport code using the
CEM03.03, Bertini, and INCL+ABLA event generators. Our results indicate the
need to accurately consider fission and fragmentation of relatively light
target nuclei like terbium in the modeling of nuclear reactions at 800 MeV. The
predictive power of the code was found to be different for each event generator
tested but was satisfactory for most of the product yields in the mass region
where spallation reactions dominate. However, none of the event generators'
results are in complete agreement with measured data.
| arxiv topic:nucl-ex nucl-th |
arxiv_dataset-35481207.1586 | Topologies of (strong) uniform convergence on bornologies
math.GN
We continue the study of topologies of strong uniform convergence on
bornologies initiated in [G. Beer and S. Levi, Strong uniform continuity, J.
Math Anal. Appl., 350:568-589, 2009] and [G. Beer and S. Levi, Uniform
continuity, uniform convergence and shields, Set-Valued and Variational
Analysis, 18:251-275, 2010]. We study cardinal invariants of topologies of
(strong) uniform convergence on bornologies on the space of continuous
real-valued functions and we also generalize some known results from the
literature.
| arxiv topic:math.GN |
arxiv_dataset-35491207.1686 | Large-mass neutron stars with hyperonization
astro-ph.SR nucl-th
Within a density-dependent relativistic mean-field model using in-medium
meson-hadron coupling constants and meson masses, we explore effects of
in-medium hyperon interactions on properties of neutron stars. It is found that
the hyperonic constituents in large-mass neutron stars can not be simply ruled
out, while the recently measured mass of the millisecond pulsar J1614-2230 can
constrain significantly the in-medium hyperon interactions. Moreover, effects
of nuclear symmetry energy on hyperonization in neutron stars are also
discussed.
| arxiv topic:astro-ph.SR nucl-th |
arxiv_dataset-35501207.1786 | Ricci-quadratic homogeneous Randers spaces
math.DG
A Finsler space is called Ricci-quadratic if its Ricci curvature $Ric(x,y)$
is quadratic in $y$. It is called a Berwald space if its Chern connection
defines a linear connection directly on the underlying manifold $M$. In this
article, we prove that a homogeneous Randers space is Ricci-quadratic if and
only if it is of Berwald type.
| arxiv topic:math.DG |
arxiv_dataset-35511207.1886 | Does quark number scaling breakdown in Pb+Pb collisions at Root_s = 2.76
TeV?
nucl-ex nucl-th
The anisotropy coefficient $v_2$, for unidentified and identified charged
hadrons [pions ($\pi$), kaons ($K$) and protons ($p$)] measured in Au+Au
collisions at $\sqrt{s_{NN}}= 0.20$ TeV (RHIC) and Pb+Pb collisions at
$\sqrt{s_{NN}}= 2.76$ TeV (LHC), are compared for several collision
centralities ($\text{cent}$) and particle transverse momenta $p_T$. In contrast
to the measurements for charged hadrons, the comparisons indicate a sizable
increase of $v_2(p_T)$ for $\pi,K$ and $p$, as well as a blueshift of proton
$v_2(p_T)$, from RHIC to LHC. When this blueshift is accounted for, the LHC
data [for $\pi$, $K$, $p$] show excellent scaling of $v_2({KE}_T)$ with the
number of valence quarks ($n_q$), for a broad range of transverse kinetic
energies (${KE}_T$) and collision centralities. These observations suggest a
larger mean sound speed $<c_s(T)>$ for the plasma created in LHC collisions,
and significant radial flow generation after its hadronization.
| arxiv topic:nucl-ex nucl-th |
arxiv_dataset-35521207.1986 | On the Capacity Region of Two-User Linear Deterministic Interference
Channel and Its Application to Multi-Session Network Coding
cs.IT math.IT
In this paper, we study the capacity of the two-user multiple-input
multiple-output (MIMO) linear deterministic interference channel (IC), with
possible correlations within/between the channel matrices. The capacity region
is characterized in terms of the rank of the channel matrices. It is shown that
\emph{linear precoding} with Han-Kobayashi type of rate-splitting, i.e.,
splitting the information-bearing symbols of each user into common and private
parts, is sufficient to achieve all the rate pairs in the derived capacity
region. The capacity result is applied to obtain an achievable rate region for
the double-unicast networks with random network coding at the intermediate
nodes, which can be modeled by the two-user MIMO linear deterministic IC
studied. It is shown that the newly proposed achievable region is strictly
larger than the existing regions in the literature.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-35531207.2086 | Cosmological Inflation and the Quantum Measurement Problem
hep-th astro-ph.CO gr-qc hep-ph quant-ph
According to cosmological inflation, the inhomogeneities in our universe are
of quantum mechanical origin. This scenario is phenomenologically very
appealing as it solves the puzzles of the standard hot big bang model and
naturally explains why the spectrum of cosmological perturbations is almost
scale invariant. It is also an ideal playground to discuss deep questions among
which is the quantum measurement problem in a cosmological context. Although
the large squeezing of the quantum state of the perturbations and the
phenomenon of decoherence explain many aspects of the quantum to classical
transition, it remains to understand how a specific outcome can be produced in
the early universe, in the absence of any observer. The Continuous Spontaneous
Localization (CSL) approach to quantum mechanics attempts to solve the quantum
measurement question in a general context. In this framework, the wavefunction
collapse is caused by adding new non linear and stochastic terms to the
Schroedinger equation. In this paper, we apply this theory to inflation, which
amounts to solving the CSL parametric oscillator case. We choose the
wavefunction collapse to occur on an eigenstate of the Mukhanov-Sasaki variable
and discuss the corresponding modified Schroedinger equation. Then, we compute
the power spectrum of the perturbations and show that it acquires a universal
shape with two branches, one which remains scale invariant and one with nS=4, a
spectral index in obvious contradiction with the Cosmic Microwave Background
(CMB) anisotropy observations. The requirement that the non-scale invariant
part be outside the observational window puts stringent constraints on the
parameter controlling the deviations from ordinary quantum mechanics...
(Abridged).
| arxiv topic:hep-th astro-ph.CO gr-qc hep-ph quant-ph |
arxiv_dataset-35541207.2186 | Warp Features in DBI Inflation
astro-ph.CO hep-th
In Dirac-Born-Infeld inflation, changes in the sound speed that transiently
break the slow roll approximation lead to features in the power spectrum. We
develop and test the generalized slow roll approximation for calculating such
effects and show that it can be extended to treat order unity features. As in
slow-roll, model independent constraints on the potential of canonical
inflation can be directly reinterpreted in the DBI context through this
approximation. In particular, a sharp horizon scale step in the warped brane
tension can explain oscillatory features in the WMAP7 CMB power spectrum as
well as features in the potential. Differences appear only as a small
suppression of power on horizon scales and larger.
| arxiv topic:astro-ph.CO hep-th |
arxiv_dataset-35551207.2286 | The chain rule implies Tsirelson's bound: an approach from generalized
mutual information
quant-ph
In order to analyze an information theoretical derivation of Tsirelson's
bound based on information causality, we introduce a generalized mutual
information (GMI), defined as the optimal coding rate of a channel with
classical inputs and general probabilistic outputs. In the case where the
outputs are quantum, the GMI coincides with the quantum mutual information. In
general, the GMI does not necessarily satisfy the chain rule. We prove that
Tsirelson's bound can be derived by imposing the chain rule on the GMI. We
formulate a principle, which we call the no-supersignalling condition, which
states that the assistance of nonlocal correlations does not increase the
capability of classical communication. We prove that this condition is
equivalent to the no-signalling condition. As a result, we show that
Tsirelson's bound is implied by the nonpositivity of the quantitative
difference between information causality and no-supersignalling.
| arxiv topic:quant-ph |
arxiv_dataset-35561207.2386 | Sequential multi-sensor change-point detection
math.ST stat.TH
We develop a mixture procedure to monitor parallel streams of data for a
change-point that affects only a subset of them, without assuming a spatial
structure relating the data streams to one another. Observations are assumed
initially to be independent standard normal random variables. After a
change-point the observations in a subset of the streams of data have nonzero
mean values. The subset and the post-change means are unknown. The procedure we
study uses stream specific generalized likelihood ratio statistics, which are
combined to form an overall detection statistic in a mixture model that
hypothesizes an assumed fraction $p_0$ of affected data streams. An analytic
expression is obtained for the average run length (ARL) when there is no change
and is shown by simulations to be very accurate. Similarly, an approximation
for the expected detection delay (EDD) after a change-point is also obtained.
Numerical examples are given to compare the suggested procedure to other
procedures for unstructured problems and in one case where the problem is
assumed to have a well-defined geometric structure. Finally we discuss
sensitivity of the procedure to the assumed value of $p_0$ and suggest a
generalization.
| arxiv topic:math.ST stat.TH |
arxiv_dataset-35571207.2486 | Inner functions on the bidisk and associated Hilbert spaces
math.FA math.CV
Matrix valued inner functions on the bidisk have a number of natural
subspaces of the Hardy space on the torus associated to them. We study their
relationship to Agler decompositions, regularity up to the boundary, and
restriction maps into one variable spaces. We give a complete description of
the important spaces associated to matrix rational inner functions. The
dimension of some of these spaces can be computed in a straightforward way, and
this ends up having an application to the study of three variable rational
inner functions. Examples are included to highlight the differences between the
scalar and matrix cases.
| arxiv topic:math.FA math.CV |
arxiv_dataset-35581207.2586 | The similarity problem for indefinite Sturm-Liouville operators and the
HELP inequality
math.SP math.AP math.CA
We study two problems. The first one is the similarity problem for the
indefinite Sturm-Liouville operator \[ A=-(\sgn\, x)\frac{d}{wdx}\frac{d}{rdx}
\] acting in $L^2_{w}(-b,b)$. It is assumed that $w,r\in L^1_{\loc}(-b,b)$ are
even and positive a.e. on $(-b,b)$.
The second object is the so-called HELP inequality
\[(\int_{0}^b\frac{1}{\tilde{r}}|f'|\, dx)^2 \le K^2
\int_{0}^b|f|^2\tilde{w}\,dx\int_{0}^b\Big|\frac{1}{\tilde{w}}\big(\frac{1}{\tilde{r}}f'\big)'\Big|^2\tilde{w}\,
dx, \] where the coefficients $\tilde{w},\tilde{r}\in L^1_{\loc}[0,b)$ are
positive a.e. on $(0,b)$.
Both problems are well understood when the corresponding Sturm-Liouville
differential expression is regular. The main objective of the present paper is
to give criteria for both the validity of the HELP inequality and the
similarity to a self-adjoint operator in the singular case. Namely, we
establish new criteria formulated in terms of the behavior of the corresponding
Weyl-Titchmarsh $m$-functions at 0 and at $\infty$. As a biproduct of this
result we show that both problems are closely connected. Namely, the operator
$A$ is similar to a self-adjoint one precisely if the HELP inequality with
$\tilde{w}=r$ and $\tilde{r}=w$ is valid.
Next we characterize the behavior of $m$-functions in terms of coefficients
and then these results enable us to reformulate the obtained criteria in terms
of coefficients. Finally, we apply these results for the study of the two-way
diffusion equation, also known as the time-independent Fokker-Plank equation.
| arxiv topic:math.SP math.AP math.CA |
arxiv_dataset-35591207.2686 | Well-established nucleon resonances revisited by double-polarization
measurements
nucl-ex
The first measurement is reported of the double-polarization observable G in
photoproduction of neutral pions off protons, covering the photon energy range
from 620 to 1120 MeV and the full solid angle. G describes the correlation
between the photon polarization plane and the scattering plane for protons
polarized along the direction of the incoming photon. The observable is highly
sensitive to contributions from baryon resonances. The new results are compared
to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of
the long-lasting efforts to understand {\gamma}p -> p{\pi} 0 as the simplest
photoproduction reaction, surprisingly large differences between the new data
and the latest predictions are observed which are traced to different
contributions of the N (1535) with spin-parity J^P = 1/2^- and N (1520) with
J^P = 3/2^- . In the third resonance region, where N (1680) with J^P = 5/2^+
production dominates, the new data are reasonably close to the predictions.
| arxiv topic:nucl-ex |
arxiv_dataset-35601207.2786 | Comment on `A scattering quantum circuit for measuring Bell's time
inequality: a nuclear magnetic resonance demonstration using maximally mixed
states'
quant-ph
A recent paper by Souza, Oliveira and Sarthour (SOS) reports the experimental
violation of a Leggett-Garg inequality (sometimes referred to as a temporal
Bell inequality). The inequality tests for quantum mechanical superposition: if
the inequality is violated, the dynamics cannot be explained by a large class
of classical theories under the heading of macrorealism. Experimental tests of
the LG inequality are beset by the difficulty of performing the necessary
so-called 'non-invasive' measurements (which for the macrorealist will extract
information from a system of interest without disturbing it). SOS argue that
they nevertheless achieve this difficult goal by putting the system in a
maximally mixed state. The system then allegedly undergoes no perturbation
during their experiment. Unfortunately the method is ultimately unconvincing to
a skeptical macrorealist, and so the conclusions drawn by SOS are unjustified.
| arxiv topic:quant-ph |
arxiv_dataset-35611207.2886 | Optimal stopping for partially observed piecewise-deterministic Markov
processes
math.PR
This paper deals with the optimal stopping problem under partial observation
for piecewise-deterministic Markov processes. We first obtain a recursive
formulation of the optimal filter process and derive the dynamic programming
equation of the partially observed optimal stopping problem. Then, we propose a
numerical method, based on the quantization of the discrete-time filter process
and the inter-jump times, to approximate the value function and to compute an
actual $\epsilon$-optimal stopping time. We prove the convergence of the
algorithms and bound the rates of convergence.
| arxiv topic:math.PR |
arxiv_dataset-35621207.2986 | One-dimensional hard rod fluid in a disordered porous medium: scaled
particle theory
cond-mat.soft
The scaled particle theory is applied to a description of thermodynamic
properties of one-dimensional hard rod fluid in disordered porous media. To
this end, we extended the SPT2 approach, which had been developed previously.
Analytical expressions are obtained for the chemical potential and pressure of
a hard-rod fluid in hard rod and overlapping hard rod matrices. A series of new
approximations for SPT2 are proposed. It is shown that apart from two well
known porosities such as geometrical porosity and specific probe particle
porosity, a new type of porosity defined by the maximum value of packing
fraction of fluid particles in porous medium should be taken into account. The
grand canonical Monte-Carlo simulations are performed to verify the accuracy of
the SPT2 approach in combination with the new approximations. It is observed
that the theoretical description proposed in this study essentially improves
the results up to the highest values of fluid densities.
| arxiv topic:cond-mat.soft |
arxiv_dataset-35631207.3086 | Superconducting instabilities of R-charged black branes
hep-th
We explore superconducting instabilities of black branes in SO(6) gauged
supergravity at finite temperature and finite R-charge densities. We compute
the critical temperatures for homogeneous neutral and superconducting
instabilities in a truncation of 20 scalars and 15 gauge fields as a function
of the chemical potentials conjugate to the three U(1) charges in SO(6). We
find that despite the imbalance provided by multiple chemical potentials there
is always at least one superconducting black brane branch, emerging at a
temperature where the normal phase is locally thermodynamically stable. We
emphasise that the three-equal charge solution, Reissner-Nordstrom, is
subdominant to a thermodynamically unstable black brane at sufficiently low
temperatures --- a feature which is hidden in an equal charge truncation.
| arxiv topic:hep-th |
arxiv_dataset-35641207.3186 | Chandra observations and classification of AGN-candidates correlated
with Auger UHECRs
astro-ph.HE astro-ph.CO
We report on Chandra X-ray observations of possible-AGNs which have been
correlated with Ultra-high Energy Cosmic Rays (UHECRs) observed by the Pierre
Auger Collaboration. Combining our X-ray observations with optical
observations, we conclude that one-third of the 21 Veron-Cetty Veron (VCV)
galaxies correlating with UHECRs in the first Auger data-release are actually
not AGNs. We review existing optical observations of the 20 VCV galaxies
correlating with UHECRs in the second Auger data-release and determine that
three of them are not AGNs and two are uncertain. Overall, of the 57 published
UHECRs with |b|>10 degrees, 22 or 23 correlate with true AGNs using the Auger
correlation parameters. We also measured the X-ray luminosity of ESO139-G12 to
complete the determination of the bolometric luminosities of AGNs correlating
with UHECRs in the first data-set. Apart from two candidate sources which
require further observation, we determined bolometric luminosities for the
candidate galaxies of the second dataset. We find that only two of the total of
69 published UHECRs correlate with AGNs (IC5135 and IC4329a) which are powerful
enough in their steady-state to accelerate protons to the observed energies of
their correlated UHECRs. The GZK expectation is that about 45% of the sources
of UHECRs above 60 EeV should be contained within the z<0.018 volume defined by
the Auger scan analysis, so an observed level of 30-50% correlation with weak
AGNs is compatible with the suggestion that AGNs experience transient
high-luminosity states during which they accelerate UHECRs.
| arxiv topic:astro-ph.HE astro-ph.CO |
arxiv_dataset-35651207.3286 | The second homology group of the homological Goldman Lie algebra
math.GT
We determine the second homology group of the homological Goldman Lie algebra
for an oriented surface.
| arxiv topic:math.GT |
arxiv_dataset-35661207.3386 | Numerical modeling of the disruption of Comet D/1993 F2 Shoemaker-Levy 9
representing the progenitor by a gravitationally bound assemblage of randomly
shaped polyhedra
astro-ph.EP
We advance the modeling of rubble-pile solid bodies by re-examining the tidal
breakup of comet Shoemaker-Levy 9, an event that occurred during a 1.33 Jupiter
radii encounter with that planet in July 1992. Tidal disruption of the comet
nucleus led to a chain of sub-nuclei about 100-1000 m in diameter; these went
on to collide with the planet two years later (Chodas & Yeomans 1996). They
were intensively studied prior to and during the collisions, making SL9 the
best natural benchmark for physical models of small body disruption. For the
first time in the study of this event, we use numerical codes treating
rubble-piles as collections of polyhedra (Korycansky & Asphaug 2009). This
introduces forces of dilatation and friction, and inelastic response. As in our
previous studies (Asphaug & Benz 1994,1996) we conclude that the progenitor
must have been a rubble-pile, and we obtain approximately the same pre-breakup
diameter (about 1.5 km) in our best fits to the data. We find that the
inclusion of realistic fragment shapes leads to grain locking and dilatancy, so
that even in the absence of friction or other dissipation we find that
disruption is overall more difficult than in our spheres-based simulations. We
constrain the comet's bulk density at about 300-400 kg/m^3, half that of our
spheres-based predictions and consistent with recent estimates derived from
spacecraft observations.
| arxiv topic:astro-ph.EP |
arxiv_dataset-35671207.3486 | Evolution from a nodeless gap to d(x2-y2) form in underdoped
La(2-x)SrxCuO4
cond-mat.supr-con cond-mat.str-el
Using angle-resolved photoemission (ARPES), it is revealed that the
low-energy electronic excitation spectra of highly underdoped superconducting
and non-superconducting La(2-x)SrxCuO4 cuprates are gapped along the entire
underlying Fermi surface at low temperatures. We show how the gap function
evolves to a d(x2-y2) form as increasing temperature or doping, consistent with
the vast majority of ARPES studies of cuprates. Our results provide essential
information for uncovering the symmetry of the order parameter(s) in strongly
underdoped cuprates, which is a prerequisite for understanding the pairing
mechanism and how superconductivity emerges from a Mott insulator.
| arxiv topic:cond-mat.supr-con cond-mat.str-el |
arxiv_dataset-35681207.3586 | Directed Acyclic Subgraph Problem Parameterized above the Poljak-Turzik
Bound
cs.DS cs.CC
An oriented graph is a directed graph without directed 2-cycles. Poljak and
Turz\'{i}k (1986) proved that every connected oriented graph $G$ on $n$
vertices and $m$ arcs contains an acyclic subgraph with at least
$\frac{m}{2}+\frac{n-1}{4}$ arcs. Raman and Saurabh (2006) gave another proof
of this result and left it as an open question to establish the parameterized
complexity of the following problem: does $G$ have an acyclic subgraph with
least $\frac{m}{2}+\frac{n-1}{4}+k$ arcs, where $k$ is the parameter? We answer
this question by showing that the problem can be solved by an algorithm of
runtime $(12k)!n^{O(1)}$. Thus, the problem is fixed-parameter tractable. We
also prove that there is a polynomial time algorithm that either establishes
that the input instance of the problem is a Yes-instance or reduces the input
instance to an equivalent one of size $O(k^2)$.
| arxiv topic:cs.DS cs.CC |
arxiv_dataset-35691207.3686 | Two-fold symmetry flattens Dirac cone of surface state at W(110)
cond-mat.mes-hall
The $C_{2v}$ symmetry of the W(110) surface influences strongly the
spin-polarized Dirac-cone-like surface state within a spin-orbit-induced
symmetry gap. We present a detailed angle-resolved photoemission study with
$s$- and $p$-polarized light along three different symmetry lines. The
Dirac-cone-like feature appears along $\bar{\Gamma}\bar{H}$ and
$\bar{\Gamma}\bar{S}$, while it is strongly deformed along
$\bar{\Gamma}\bar{N}$. A two-fold $\Sigma_{3}$ symmetry of the $d$-type surface
state is identified from photoemission experiments using linear polarized
light. Our results are well described by model calculations based on an
effective Hamiltonian with $C_{2v}$ symmetry including Rashba parameters up to
third order. The flattened Dirac cone of the surface state is caused by
hybridization with bulk continuum states of $\Sigma_{1}$ and $\Sigma_{2}$
symmetry. The spin texture of this state obtained from the model calculations
shows a quasi-one dimensional behavior. This finding opens a new avenue in the
study of $d$-electron-based persistent spin helix systems and/or weak
topological insulators.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-35701207.3786 | Bounce and cyclic cosmology in extended nonlinear massive gravity
astro-ph.CO gr-qc hep-th
We investigate non-singular bounce and cyclic cosmological evolutions in a
universe governed by the extended nonlinear massive gravity, in which the
graviton mass is promoted to a scalar-field potential. The extra freedom of the
theory can lead to certain energy conditions violations and drive cyclicity
with two different mechanisms: either with a suitably chosen scalar-field
potential under a given Stuckelberg-scalar function, or with a suitably chosen
Stuckelberg-scalar function under a given scalar-field potential. Our analysis
shows that extended nonlinear massive gravity can alter significantly the
evolution of the universe at both early and late times.
| arxiv topic:astro-ph.CO gr-qc hep-th |
arxiv_dataset-35711207.3886 | Bipolar-Driven Large Magnetoresistance in Silicon
cond-mat.mtrl-sci
Large linear magnetoresistance (MR) in electron-injected p-type silicon at
very low magnetic field is observed experimentally at room temperature. The
large linear MR is induced in electron-dominated space-charge transport regime,
where the magnetic field modulation of electron-to-hole density ratio controls
the MR, as indicated by the magnetic field dependence of Hall coefficient in
the silicon device. Contrary to the space-charge-induced MR effect in unipolar
silicon device, where the large linear MR is inhomogeneity-induced, our results
provide a different insight into the mechanism of large linear MR in
non-magnetic semiconductors that is not based on the inhomogeneity model. This
approach enables homogeneous semiconductors to exhibit large linear MR at low
magnetic fields that until now has only been appearing in semiconductors with
strong inhomogeneities.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-35721207.3986 | Persistency of entanglement and nonlocality in multipartite quantum
systems
quant-ph
The behaviour under particle loss of entanglement and nonlocality is
investigated in multipartite quantum systems. In particular, we define a notion
of persistency of nonlocality, which leads to device-independent tests of
persistent entanglement. We investigate the persistency of various classes of
multipartite quantum states, exhibiting a variety of different behaviours. A
particular attention is devoted to states featuring maximal persistency.
Finally we discuss a link between the symmetry of a state and its persistency,
illustrating the fact that too much symmetry reduces the strength of
correlations among subsystems. These ideas also lead to a device-independent
estimation of the asymmetry of a quantum state.
| arxiv topic:quant-ph |
arxiv_dataset-35731207.4086 | The Hopf conjecture for manifolds with low cohomogeneity or high
symmetry rank
math.DG
We prove that the Euler characteristic of an even-dimensional compact
manifold with positive (nonnegative) sectional curvature is positive
(nonnegative) provided that the manifold admits an isometric action of a
compact Lie group $G$ with principal isotropy group $H$ and cohomogeneity $k$
such that $k - (\rank G - \rank H)\le 5$. Moreover, we prove that the Euler
characteristic of a compact Riemannian manifold $M^{4l+4}$ or $M^{4l+2}$ with
positive sectional curvature is positive if $M$ admits an effective isometric
action of a torus $T^l$, i.e., if the symmetry rank of $M$ is $\ge l$.
| arxiv topic:math.DG |
arxiv_dataset-35741207.4186 | Modeling Dust and Starlight in Galaxies Observed by Spitzer and
Herschel: NGC 628 and NGC 6946
astro-ph.CO astro-ph.GA
We characterize the dust in NGC628 and NGC6946, two nearby spiral galaxies in
the KINGFISH sample. With data from 3.6um to 500um, dust models are strongly
constrained. Using the Draine & Li (2007) dust model, (amorphous silicate and
carbonaceous grains), for each pixel in each galaxy we estimate (1) dust mass
surface density, (2) dust mass fraction contributed by polycyclic aromatic
hydrocarbons (PAH)s, (3) distribution of starlight intensities heating the
dust, (4) total infrared (IR) luminosity emitted by the dust, and (5) IR
luminosity originating in regions with high starlight intensity. We obtain maps
for the dust properties, which trace the spiral structure of the galaxies. The
dust models successfully reproduce the observed global and resolved spectral
energy distributions (SEDs). The overall dust/H mass ratio is estimated to be
0.0082+/-0.0017 for NGC628, and 0.0063+/-0.0009 for NGC6946, consistent with
what is expected for galaxies of near-solar metallicity. Our derived dust
masses are larger (by up to a factor 3) than estimates based on
single-temperature modified blackbody fits. We show that the SED fits are
significantly improved if the starlight intensity distribution includes a
(single intensity) "delta function" component. We find no evidence for
significant masses of cold dust T<12K. Discrepancies between PACS and MIPS
photometry in both low and high surface brightness areas result in large
uncertainties when the modeling is done at PACS resolutions, in which case
SPIRE, MIPS70 and MIPS160 data cannot be used. We recommend against attempting
to model dust at the angular resolution of PACS.
| arxiv topic:astro-ph.CO astro-ph.GA |
arxiv_dataset-35751207.4286 | Transfer Function Synthesis without Quantifier Elimination
cs.LO
Traditionally, transfer functions have been designed manually for each
operation in a program, instruction by instruction. In such a setting, a
transfer function describes the semantics of a single instruction, detailing
how a given abstract input state is mapped to an abstract output state. The net
effect of a sequence of instructions, a basic block, can then be calculated by
composing the transfer functions of the constituent instructions. However,
precision can be improved by applying a single transfer function that captures
the semantics of the block as a whole. Since blocks are program-dependent, this
approach necessitates automation. There has thus been growing interest in
computing transfer functions automatically, most notably using techniques based
on quantifier elimination. Although conceptually elegant, quantifier
elimination inevitably induces a computational bottleneck, which limits the
applicability of these methods to small blocks. This paper contributes a method
for calculating transfer functions that finesses quantifier elimination
altogether, and can thus be seen as a response to this problem. The
practicality of the method is demonstrated by generating transfer functions for
input and output states that are described by linear template constraints,
which include intervals and octagons.
| arxiv topic:cs.LO |
arxiv_dataset-35761207.4386 | Hecke Transformations of Conformal Blocks in WZW Theory. I. KZB
Equations for Non-Trivial Bundles
math-ph hep-th math.MP math.RT nlin.SI
We describe new families of the Knizhnik-Zamolodchikov-Bernard (KZB)
equations related to the WZW-theory corresponding to the adjoint $G$-bundles of
different topological types over complex curves $\Sigma_{g,n}$ of genus $g$
with $n$ marked points. The bundles are defined by their characteristic classes
- elements of $H^2(\Sigma_{g,n},\mathcal{Z}(G))$, where $\mathcal{Z}(G)$ is a
center of the simple complex Lie group $G$. The KZB equations are the
horizontality condition for the projectively flat connection (the KZB
connection) defined on the bundle of conformal blocks over the moduli space of
curves. The space of conformal blocks has been known to be decomposed into a
few sectors corresponding to the characteristic classes of the underlying
bundles. The KZB connection preserves these sectors. In this paper we construct
the connection explicitly for elliptic curves with marked points and prove its
flatness.
| arxiv topic:math-ph hep-th math.MP math.RT nlin.SI |
arxiv_dataset-35771207.4486 | Detection of Iron K{\alpha} Emission from a Complete Sample of
Submillimeter Galaxies
astro-ph.CO
We present an X-ray stacking analysis of a sample of 38 submillimeter
galaxies with <z>=2.6 discovered at >4{\sigma} significance in the Lockman Hole
North with the MAMBO array. We find a 5{\sigma} detection in the stacked soft
band (0.5-2.0 keV) image, and no significant detection in the hard band (2.0-8
keV). We also perform rest-frame spectral stacking based on spectroscopic and
photometric redshifts and find a ~4{\sigma} detection of Fe K{\alpha} emission
with an equivalent width of EW>1 keV. The centroid of the Fe K{\alpha} emission
lies near 6.7 keV, indicating a possible contribution from highly ionized Fe
XXV or Fe XXVI; there is also a slight indication that the line emission is
more spatially extended than the X-ray continuum. This is the first X-ray
analysis of a complete, flux-limited sample of SMGs with statistically robust
radio counterparts.
| arxiv topic:astro-ph.CO |
arxiv_dataset-35781207.4586 | Persistent and anti-persistent pattern in stride-to-stride variability
of treadmill walking: influence of rhythmic auditory cueing
q-bio.NC
It has been observed that long time series of Stride Time (ST), Stride Length
(SL) and Stride Speed (SS=SL/ST) exhibited statistical persistence (long-range
auto-correlation) in overground walking. Rhythmic auditory cueing induced
anti-persistent (or anti-correlated) pattern in ST series, while SL and SS
remained persistent. On the other hand, it has been shown that SS became
anti-persistent in treadmill walking, while ST and SL remained persistent. The
aim of this study was to analyze the effect of the combination of treadmill
walking (imposed speed) and auditory cueing (imposed cadence) on gait dynamics.
Twenty middle-aged subjects performed 6 x 5min walking trials at various
imposed speeds on an instrumented treadmill. Freely-chosen walking cadences
were measured during the first three trials, and then imposed accordingly in
the last three trials by using a metronome. Detrended fluctuation analysis
(DFA) was performed on the times series of ST, SL, and SS. Treadmill induced
anti-persistent dynamics in the time series of SS, but preserved the
persistence of ST and SL. On the contrary, all the three parameters were
anti-persistent under dual-constraints condition. Anti-persistent dynamics may
be related to a tighter control: deviations are followed by a rapid
over-correction, what produces oscillations around target values. Under single
constraint condition, while SS is tightly regulated in order to follow the
treadmill speed, redundancy between ST and SL would likely allow persistent
pattern to occur. Conversely, under dual constraint conditions, the absence of
redundancy among SL, ST and SS would explain the generalized anti-persistent
pattern.
| arxiv topic:q-bio.NC |
arxiv_dataset-35791207.4686 | Search for top and bottom squarks from gluino pair production in final
states with missing transverse energy and at least three b-jets with the
ATLAS detector
hep-ex
This letter reports the results of a search for top and bottom squarks from
gluino pair production in 4.7 fb^-1 of pp collisions at sqrt(s) = 7 TeV using
the ATLAS detector at the LHC. The search is performed in events with large
missing transverse momentum and at least three jets identified as originating
from a b-quark. Exclusion limits are presented for a variety of gluino-mediated
models with gluino masses up to 1 TeV excluded.
| arxiv topic:hep-ex |
arxiv_dataset-35801207.4786 | Defense mechanisms of empathetic players in the spatial ultimatum game
physics.soc-ph cond-mat.stat-mech physics.bio-ph q-bio.PE
Experiments on the ultimatum game have revealed that humans are remarkably
fond of fair play. When asked to share an amount of money, unfair offers are
rare and their acceptance rate small. While empathy and spatiality may lead to
the evolution of fairness, thus far considered continuous strategies have
precluded the observation of solutions that would be driven by pattern
formation. Here we introduce a spatial ultimatum game with discrete strategies,
and we show that this simple alteration opens the gate to fascinatingly rich
dynamical behavior. Besides mixed stationary states, we report the occurrence
of traveling waves and cyclic dominance, where one strategy in the cycle can be
an alliance of two strategies. The highly webbed phase diagram, entailing
continuous and discontinuous phase transitions, reveals hidden complexity in
the pursuit of human fair play.
| arxiv topic:physics.soc-ph cond-mat.stat-mech physics.bio-ph q-bio.PE |
arxiv_dataset-35811207.4886 | Efficient computation with a linear mixed model on large-scale data sets
with applications to genetic studies
stat.AP
Motivated by genome-wide association studies, we consider a standard linear
model with one additional random effect in situations where many predictors
have been collected on the same subjects and each predictor is analyzed
separately. Three novel contributions are (1) a transformation between the
linear and log-odds scales which is accurate for the important genetic case of
small effect sizes; (2) a likelihood-maximization algorithm that is an order of
magnitude faster than the previously published approaches; and (3) efficient
methods for computing marginal likelihoods which allow Bayesian model
comparison. The methodology has been successfully applied to a large-scale
association study of multiple sclerosis including over 20,000 individuals and
500,000 genetic variants.
| arxiv topic:stat.AP |
arxiv_dataset-35821207.4986 | Parafermion excitations in superfluid of quasi-molecular chains
cond-mat.other cond-mat.quant-gas
We study a quantum phase transition in a system of dipoles confined in a
stack of $N$ identical one-dimensional lattices (tubes) polarized
perpendicularly to the lattices. In this arrangement the intra-lattice
interaction is purely repulsive preventing the system collapse and the
inter-lattice one is attractive. The dipoles may represent polar molecules or
indirect excitons. The transition separates two phases; in one of them
superfluidity (understood as algebraic decay of the corresponding correlation
functions) takes place in each individual lattice, in the other (chain
superfluid) the order parameter is the product of bosonic operators from all
lattices. We argue that in the presence of finite inter-lattice tunneling the
transition belongs to the universality class of the $q=N$ two-dimensional
classical Potts model. For $N=2,3,4$ the corresponding low energy field theory
is the model of Z$_N$ parafermions perturbed by the thermal operator. Results
of Monte Carlo simulations are consistent with these predictions. The detection
scheme for the chain superfluid of indirect excitons is outlined.
| arxiv topic:cond-mat.other cond-mat.quant-gas |
arxiv_dataset-35831207.5086 | Assume-Guarantee Abstraction Refinement for Probabilistic Systems
cs.LO cs.FL
We describe an automated technique for assume-guarantee style checking of
strong simulation between a system and a specification, both expressed as
non-deterministic Labeled Probabilistic Transition Systems (LPTSes). We first
characterize counterexamples to strong simulation as "stochastic" trees and
show that simpler structures are insufficient. Then, we use these trees in an
abstraction refinement algorithm that computes the assumptions for
assume-guarantee reasoning as conservative LPTS abstractions of some of the
system components. The abstractions are automatically refined based on tree
counterexamples obtained from failed simulation checks with the remaining
components. We have implemented the algorithms for counterexample generation
and assume-guarantee abstraction refinement and report encouraging results.
| arxiv topic:cs.LO cs.FL |
arxiv_dataset-35841207.5186 | The Surface Tension of Quark Matter in a Geometrical Approach
hep-ph astro-ph.HE cond-mat.other nucl-th
The surface tension of quark matter plays a crucial role for the possibility
of quark matter nucleation during the formation of compact stellar objects,
because it determines the nucleation rate and the associated critical size.
However, this quantity is not well known and the theoretical estimates fall
within a wide range, $\gamma_0 \approx 5-300 MeV/fm^2$. We show here that once
the equation of state is available one may use a geometrical approach to obtain
a numerical value for the surface tension that is consistent with the model
approximations adopted. We illustrate this method within the two-flavor linear
\sigma model and the Nambu--Jona-Lasinio model with two and three flavors.
Treating these models in the mean-field approximation, we find $\gamma_0
\approx 7-30 MeV/fm^2$. Such a relatively small surface tension would favor the
formation of quark stars and may thus have significant astrophysical
implications. We also investigate how the surface tension decreases towards
zero as the temperature is raised from zero to its critical value.
| arxiv topic:hep-ph astro-ph.HE cond-mat.other nucl-th |
arxiv_dataset-35851207.5286 | Backward stochastic partial differential equations with quadratic growth
math.PR math.OC
This paper is concerned with the existence and uniqueness of weak solutions
to the Cauchy-Dirichlet problem of backward stochastic partial differential
equations (BSPDEs) with nonhomogeneous terms of quadratic growth in both the
gradient of the first unknown and the second unknown. As an example, we
consider a non-Markovian stochastic optimal control problem with cost
functional formulated by a quadratic BSDE, where the corresponding value
function satisfies the above quadratic BSPDE.
| arxiv topic:math.PR math.OC |
arxiv_dataset-35861207.5386 | Verification of state and entanglement with incomplete tomography
quant-ph
There exists, in general, a convex set of quantum state estimators that
maximize the likelihood for informationally incomplete data. We propose an
estimation scheme, catered to measurement data of this kind, to search for the
exact maximum-likelihood-maximum-entropy estimator using semidefinite
programming and a standard multi-dimensional function optimization routine.
This scheme can be used to infer the expectation values of a set of
entanglement witnesses that can be used to verify the entanglement of the
unknown quantum state for composite systems. Next, we establish an alternative
numerical scheme that is more computationally robust for the sole purpose of
maximizing the likelihood and entropy.
| arxiv topic:quant-ph |
arxiv_dataset-35871207.5486 | Heavy Quarkonium in the Quark Gluon Plasma from Effective Field Theories
and Potentials
hep-ph nucl-ex nucl-th
The measurements of heavy quarkonium suppression at RHIC and LHC urge theory
to develop intuitive as well as quantitative methods for the description of
$Q\bar{Q}$ melting in the quark-gluon plasma. Here I will present a brief
sketch on the effective field theory strategies underlying the definition of
the heavy quark static potential and report on two recent advances in the
extraction and interpretation of such a potential. On the one side, progress
has been made in obtaining its values from lattice QCD, which promises to make
possible investigating its real and imaginary part non-perturbatively. On the
other side, the existence of an imaginary part emphasizes the dynamical nature
of the melting process and invites us to make a direct connection to the
framework of open quantum systems.
| arxiv topic:hep-ph nucl-ex nucl-th |
arxiv_dataset-35881207.5586 | Persistent current induced by quantum light
cond-mat.mes-hall cond-mat.supr-con
It is demonstrated that the strong coupling of an electron gas to photons in
systems with broken time-reversal symmetry results in bound electron-photon
states which cannot be backscattered elastically. As a consequence, the
electron gas can flow without dissipation. This quantum macroscopic phenomenon
leads to the unconventional superconductivity which is analyzed theoretically
for a two-dimensional electron system in a semiconductor quantum well exposed
to an in-plane magnetic field.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-35891207.5686 | Spectral Analysis and Long-Time Behaviour of a Fokker-Planck Equation
with a Non-Local Perturbation
math.AP math.SP
In this article we consider a Fokker-Planck equation with a non-local, mass
preserving perturbation. We show that the perturbed Fokker-Planck operator
generates a $C_0$-semigroup on an exponentially weighted $L^2$-space.
Surprisingly, the spectrum of the Fokker-Planck operator is not affected by the
perturbation. In particular there still exists a unique (normalized) stationary
solution of the perturbed equation. And we have convergence towards the
stationary state with exponential rate -1, the same rate as for the unperturbed
Fokker-Planck equation. Moreover, for any $k\in\mathbb N$ there exists an
invariant subspace with finite codimension in which the exponential decay rate
equals $-k$. As a byproduct of our analysis we characterize the spectrum of the
Fokker-Planck operator in $L^2$-spaces with exponential weights.
| arxiv topic:math.AP math.SP |
arxiv_dataset-35901207.5786 | Principal torus bundles of Lorentzian S-manifolds and the {\phi}-null
Osserman condition
math.DG
The main result we give in this brief note relates, under suitable
hypotheses, the {\phi}-null Osserman, the null Osserman and the classical
Osserman conditions to each other, via semi-Riemannian submersions as
projection maps of principal torus bundles arising from a Lorentzian
S-manifold.
| arxiv topic:math.DG |
arxiv_dataset-35911207.5886 | Modified holographic Ricci dark energy model and statefinder diagnosis
in flat universe
astro-ph.CO
Evolution of the universe with modified holographic Ricci dark energy model
is considered. Dependency of the equation of state parameter and deceleration
parameter on the redshift and model parameters are obtained. It is shown that
the density evolution of both non-relativistic matter and dark energy are the
same until recent times. The evolutionary trajectories of the model for
different model parameters are obtained in the statefinder planes, r-s and r-q
planes. The present statefinder parameters are obtained for different model
parameter values, using that the model is differentiated from other standard
models like $\Lambda$CDM model etc. We have also shown that the evolutionary
trajectories are depending on the model parameters, and at past times the dark
energy is behaving like cold dark matter, with equation of state equal to zero.
| arxiv topic:astro-ph.CO |
arxiv_dataset-35921207.5986 | The Pohozaev identity for the fractional Laplacian
math.AP
In this paper we prove the Pohozaev identity for the semilinear Dirichlet
problem $(-\Delta)^s u = f(u)$ in $\Omega$, $u \equiv 0$ in $\mathbb
R^n\setminus\Omega$. Here, $s\in(0,1)$, $(-\Delta)^s$ is the fractional
Laplacian in $\mathbb R^n$, and $\Omega$ is a bounded $C^{1,1}$ domain.
To establish the identity we use, among other things, that if $u$ is a
bounded solution then $u/\delta^s|_{\Omega}$ is $C^\alpha$ up to the boundary
$\partial\Omega$, where $\delta(x)={\rm dist}(x,\partial\Omega)$. In the
fractional Pohozaev identity, the function $u/\delta^s|_{\partial\Omega}$ plays
the role that $\partial u/\partial\nu$ plays in the classical one.
Surprisingly, from a nonlocal problem we obtain an identity with a boundary
term (an integral over $\partial\Omega$) which is completely local.
As an application of our identity, we deduce the nonexistence of nontrivial
solutions in star-shaped domains for supercritical nonlinearities.
| arxiv topic:math.AP |
arxiv_dataset-35931207.6086 | Bipolar jets launched from magnetically diffusive accretion disks. I.
Ejection efficiency vs field strength and diffusivity
astro-ph.HE astro-ph.SR
We investigate the launching of jets and outflows from magnetically diffusive
accretion disks. Using the PLUTO code we solve the time-dependent resistive MHD
equations taking into account the disk and jet evolution simultaneously. The
main question we address is which kind of disks do launch jets and which kind
of disks do not? In particular, we study how the magnitude and distribution of
the (turbulent) magnetic diffusivity affect mass loading and jet acceleration.
We have applied a turbulent magnetic diffusivity based on \alpha-prescription,
but have also investigate examples where the scale height of diffusivity is
larger than that of the disk gas pressure. We further investigate how the
ejection efficiency is governed by the magnetic field strength. Our simulations
last for up to 5000 dynamical time scales corresponding to 900 orbital periods
of the inner disk. As a general result we observe a continuous and robust
outflow launched from the inner part of the disk, expanding into a collimated
jet of super fast magneto-sonic speed. For long time scales the disk internal
dynamics changes, as due to outflow ejection and disk accretion the disk mass
decreases. For magneto-centrifugally driven jets we find that for i) less
diffusive disks, ii) a stronger magnetic field, iii) a low poloidal
diffusivity, or a iv) lower numerical diffusivity (resolution), the mass
loading of the outflow is increased - resulting in more powerful jets with high
mass flux. For weak magnetization the (weak) outflow is driven by the magnetic
pressure gradient. We further investigate the jet asymptotic velocity and the
jet rotational velocity in respect of the different launching scenarios. We
find a lower degree of jet collimation than previous studies, most probably due
to our revised outflow boundary condition.
| arxiv topic:astro-ph.HE astro-ph.SR |
arxiv_dataset-35941207.6186 | A Dynamical Model for Operational Risk in Banks
q-fin.RM
Operational risk is the risk relative to monetary losses caused by failures
of bank internal processes due to heterogeneous causes. A dynamical model
including both spontaneous generation of losses and generation via interactions
between different processes is presented; the efforts made by the bank to avoid
the occurrence of losses is also taken into account. Under certain hypotheses,
the model can be exactly solved and, in principle, the solution can be
exploited to estimate most of the model parameters from real data. The
forecasting power of the model is also investigated and proved to be
surprisingly remarkable.
| arxiv topic:q-fin.RM |
arxiv_dataset-35951207.6286 | Classical W-algebras and generalized Drinfeld-Sokolov bi-Hamiltonian
systems within the theory of Poisson vertex algebras
math-ph math.MP math.RA math.RT nlin.SI
We provide a description of the Drinfeld-Sokolov Hamiltonian reduction for
the construction of classical W-algebras within the framework of Poisson vertex
algebras. In this context, the gauge group action on the phase space is
translated in terms of (the exponential of) a Lie conformal algebra action on
the space of functions. Following the ideas of Drinfeld and Sokolov, we then
establish under certain sufficient conditions the applicability of the
Lenard-Magri scheme of integrability and the existence of the corresponding
integrable hierarchy of bi-Hamiltonian equations.
| arxiv topic:math-ph math.MP math.RA math.RT nlin.SI |
arxiv_dataset-35961207.6386 | Search for a Higgs boson in the diphoton final state using the full CDF
data set from proton-antiproton collisions at \surds = 1.96 TeV
hep-ex
A search for a narrow Higgs boson resonance in the diphoton mass spectrum is
presented based on data corresponding to 10 fb-1 of integrated luminosity from
proton-antiproton collisions at \surds = 1.96 TeV collected by the CDF
experiment. In addition to searching for a resonance in the diphoton mass
spectrum, we employ a multivariate discriminant technique for the first time in
this channel at CDF. No evidence of signal is observed, and upper limits are
set on the cross section times branching ratio of the resonant state as a
function of Higgs boson mass. The limits are interpreted in the context of the
standard model with an expected (observed) limit on the cross section times
branching ratio of 9.9 (17.0) times the standard model prediction at the 95%
credibility level for a Higgs boson mass of 125 GeV/c2. Moreover, a Higgs boson
with suppressed couplings to fermions is excluded for masses below 114 GeV/c2
at the 95% credibility level.
| arxiv topic:hep-ex |
arxiv_dataset-35971207.6486 | Reconstruction of the electron-phonon interaction function in Ta,
2H-NbSe2 and MgB2 from spectra of S - c - N point-contacts
cond-mat.supr-con
Using Ta, 2H-NbSe2 and MgB2 as an example it is shown that it is possible to
reconstruct qualitatively a function of the electron-phonon interaction from
point-contact spectra in a superconducting state. The limits and the
restrictions of this method are also shown. The results obtained are compared
with available literature data.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-35981207.6586 | Cross time-bin photonic entanglement for quantum key distribution
quant-ph
We report a fully fibered source emitting cross time-bin entangled photons at
1540 nm from type-II spontaneous parametric down conversion. Compared to
standard time-bin entanglement realizations, the preparation interferometer
requires no phase stabilization, simplifying its implementation in quantum key
distribution experiments. Franson/Bell-type tests of such a cross time-bin
state are performed and lead to two-photon interference raw visibilities
greater than 95%, which are only limited by the dark-counts in the detectors
and imperfections in the analysis system. Just by trusting the randomness of
the beam-splitters, the correlations generated by the source can be proved of
non-classical origin even in a passive implementation. The obtained results
confirm the suitability of this source for time-bin based quantum key
distribution.
| arxiv topic:quant-ph |
arxiv_dataset-35991207.6686 | Ultrafast optical control of magnetization in EuO thin films
cond-mat.mtrl-sci
All-optical pump-probe detection of magnetization precession has been
performed for ferromagnetic EuO thin films at 10 K. We demonstrate that the
circularly-polarized light can be used to control the magnetization precession
on an ultrafast time scale. This takes place within the 100 fs duration of a
single laser pulse, through combined contribution from two nonthermal
photomagnetic effects, i.e., enhancement of the magnetization and an inverse
Faraday effect. From the magnetic field dependences of the frequency and the
Gilbert damping parameter, the intrinsic Gilbert damping coefficient is
evaluated to be {\alpha} \approx 3\times10^-3.
| arxiv topic:cond-mat.mtrl-sci |
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