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arxiv_dataset-59001501.03252 | Muonless Events in ICAL at INO
physics.ins-det hep-ex
The primary physics signal events in the ICAL at INO are the ${\nu}_{\mu}$
charged current (CC) interactions with a well defined muon track. Apart from
these events, ICAL can also detect other types of neutrino interactions, i.e.
the electron neutrino charged current interactions and the neutral current
events. It is possible to have a dataset containing mostly ${\nu}_e$CC events,
by imposing appropriate selection cuts on the events. The ${\nu}_{\mu}$ CC and
the neutral current events form the background to these events. This study uses
the Monte Carlo generated neutrino events, to design the necessary selection
cuts to obtain a ${\nu}_e$ CC rich dataset. An optimized set of constraints are
developed which balance the need for improving the purity of the sample and
having a large enough event sample. Depending on the constraints used, one can
obtain a neutrino data sample, with the purity of ${\nu}_e$ events varying
between 55% to 70%.
| arxiv topic:physics.ins-det hep-ex |
arxiv_dataset-59011501.03352 | Capability of Quasar Selection by Combining the SCUSS and SDSS
Observations
astro-ph.GA
The South Galactic Cap $u$-band Sky Survey (SCUSS) provides a deep $u$-band
imaging of about 5000 deg$^2$ in south Galactic cap. It is about 1.5 mag deeper
than the SDSS $u$-band. In this paper we evaluate the capability of quasar
selection using both SCUSS and SDSS data, based on considerations of the deep
SCUSS $u$-band imaging and two-epoch $u$-band variability. We find that the
combination of the SCUSS $u$-band and the SDSS $griz$ band allows us to select
more faint quasars and more quasars at redshift around 2.2 than the selection
only with the SDSS $ugriz$ data. Quasars have significant $u$-band
variabilities. The fraction of quasars with large two-epoch variability is much
higher than that of stars. The selection by variability can select both
low-redshift quasars with ultraviolet excess and mid-redshift ($2 < z <3.5$)
quasars where quasar selection by optical colors is inefficient. The above two
selections are complementary and make full use of the SCUSS u-band advantages.
| arxiv topic:astro-ph.GA |
arxiv_dataset-59021501.03452 | Bright but slow - Type II supernovae from OGLE-IV - Implications for
magnitude limited surveys
astro-ph.HE astro-ph.CO
We study a sample of 11 Type II supernovae (SNe) discovered by the OGLE-IV
survey. All objects have well sampled I-band light curves, and at least one
spectrum. We find that 2 or 3 of the 11 SNe have a declining light curve, and
spectra consistent with other SNe II-L, while the rest have plateaus that can
be as short as 70d, unlike the 100d typically found in nearby galaxies. The
OGLE SNe are also brighter, and show that magnitude limited surveys find SNe
that are different than usually found in nearby galaxies. We discuss this
sample in the context of understanding Type II SNe as a class and their
suggested use as standard candles.
| arxiv topic:astro-ph.HE astro-ph.CO |
arxiv_dataset-59031501.03552 | Higgs data constraints on the minimal supersymmetric standard model
hep-ph
We perform global fits to the most recent data (after summer 2014) on Higgs
boson signal strengths in the framework of the minimal supersymmetric standard
model (MSSM). We further impose the existing limits on the masses of charginos,
staus, stops and sbottoms together with the current Higgs mass constraint
$|M_{H_1} - 125.5\,{\rm GeV}| < 6$ GeV. The heavy supersymmetric (SUSY)
particles such as squarks enter into the loop factors of the $Hgg$ and
$H\gamma\gamma$ vertices while other SUSY particles such as sleptons and
charginos also enter into that of the $H\gamma\gamma$ vertex. We also take into
account the possibility of other light particles such as other Higgs bosons and
neutralinos, such that the 125.5 GeV Higgs boson can decay into. We use the
data from the ATLAS, CMS, and the Tevatron, with existing limits on SUSY
particles, to constrain on the relevant SUSY parameters. We obtain allowed
regions in the SUSY parameter space of squark, slepton and chargino masses, and
the $\mu$ parameter. We find that $|\Delta S^\gamma/S^\gamma_{\rm SM}|\lsim
0.1$ at $68\%$ confidence level when $M_{\tilde{\chi}^{\pm}_1}>300$ GeV and
$M_{\tilde{\tau}_1}>300$ GeV, irrespective of the squarks masses. Furthermore,
$|\Delta S^\gamma/S^\gamma_{\rm SM}|\lsim 0.03 $ when
$M_{\tilde{\chi}^\pm_1,{\tilde{\tau}_1}} > 500$ GeV and $M_{{\tilde
t}_1,{\tilde b}_1} \gsim 600$ GeV.
| arxiv topic:hep-ph |
arxiv_dataset-59041501.03652 | Aharonov Bohm effect in 2D topological insulator
cond-mat.mes-hall
We present magnetotransport measurements in HgTe quantum well with inverted
band structure, which expected to be a two-dimensional topological insulator
having the bulk gap with helical gapless states at the edge. The negative
magnetoresistance is observed in the local and nonlocal resistance
configuration followed by the periodic oscillations damping with magnetic
field. We attribute such behaviour to Aharonov-Bohm effect due to magnetic flux
through the charge carrier puddles coupled to the helical edge states. The
characteristic size of these puddles is about 100 nm.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-59051501.03752 | Boundary Effects in Bosonic and Fermionic Field Theories
hep-th math-ph math.MP quant-ph
The dynamics of quantum field theories on bounded domains requires the
introduction of boundary conditions on the quantum fields. We address the
problem from a very general perspective by using charge conservation as a
fundamental principle for scalar and fermionic quantum field theories.
Unitarity arises as a consequence of the choice of charge preserving boundary
conditions. This provides a powerful framework for the analysis of global
geometrical and topological properties of the space of physical boundary
conditions. Boundary conditions which allow the existence of edge states can
only arise in theories with a mass gap which is also a physical requirement for
topological insulators.
| arxiv topic:hep-th math-ph math.MP quant-ph |
arxiv_dataset-59061501.03852 | High Pressure Measurements of the Resistivity of $\beta$-YbAlB$_4$
cond-mat.str-el
The electric resistivity $\rho(T)$ under hydrostatic pressure up to 8 GPa was
measured above 2 K using a high-quality single crystal of the Yb-based heavy
fermion system $\beta$-YbAlB$_4$. We found pressure-induced magnetic ordering
above the critical pressure $P_{\rm c} \approx $ 2.4 GPa. This phase transition
temperature $T_M$ is enhanced with pressure and reaches 30 K at a pressure of 8
GPa, which is the highest transition temperature for the Yb-based heavy fermion
compounds. In contrast, the resistivity is insensitive to pressure below $P_c$
and exhibits the $T$-linear behavior in the temperature range between 2 and 20
K. Our results indicate that quantum criticality for $\beta$-YbAlB$_4$ is also
located near $P_{\rm c}$ in addition to the ambient pressure.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-59071501.03952 | Mind the Gap: Subspace based Hierarchical Domain Adaptation
cs.CV
Domain adaptation techniques aim at adapting a classifier learnt on a source
domain to work on the target domain. Exploiting the subspaces spanned by
features of the source and target domains respectively is one approach that has
been investigated towards solving this problem. These techniques normally
assume the existence of a single subspace for the entire source / target
domain. In this work, we consider the hierarchical organization of the data and
consider multiple subspaces for the source and target domain based on the
hierarchy. We evaluate different subspace based domain adaptation techniques
under this setting and observe that using different subspaces based on the
hierarchy yields consistent improvement over a non-hierarchical baseline
| arxiv topic:cs.CV |
arxiv_dataset-59081501.04052 | Convexity of Energy-Like Functions: Theoretical Results and Applications
to Power System Operations
math.OC
Power systems are undergoing unprecedented transformations with the
incorporation of larger amounts of renewable energy sources, distributed
generation and demand response. All these changes, while potentially making
power grids more responsive, efficient and resilient, also pose significant
implementation challenges. In particular, operating the new power grid will
require new tools and algorithms capable of predicting if the current state of
the system is operationally safe. In this paper we study and generalize the
so-called energy function as a tool to design algorithms to test if a
high-voltage power transmission system is within the allowed operational
limits. In the past the energy function technique was utilized primarily to
access the power system transient stability. In this manuscript, we take a new
look at energy functions and focus on an aspect that has previously received
little attention: Convexity. We characterize the domain of voltage magnitudes
and phases within which the energy function is convex. We show that the domain
of the energy function convexity is sufficiently large to include most
operationally relevant and practically interesting cases. We show how the
energy function convexity can be used to analyze power flow equations, e.g. to
certify solution uniqueness or non-existence within the domain of convexity.
This and other useful features of the generalized energy function are described
and illustrated on IEEE 14 and 118 bus models.
| arxiv topic:math.OC |
arxiv_dataset-59091501.04152 | Efficient Sensor Fault Detection Using Group Testing
cs.SY
When faulty sensors are rare in a network, diagnosing sensors individually is
inefficient. This study introduces a novel use of concepts from group testing
and Kalman filtering in detecting these rare faulty sensors with significantly
fewer number of tests. By assigning sensors to groups and performing Kalman
filter-based fault detection over these groups, we obtain binary detection
outcomes, which can then be used to recover the fault state of all sensors. We
first present this method using combinatorial group testing. We then present a
novel adaptive group testing method based on Bayesian inference. This adaptive
method further reduces the number of required tests and is suitable for noisy
group test systems. Compared to non-group testing methods, our algorithm
achieves similar detection accuracy with fewer tests and thus lower
computational complexity. Compared to other adaptive group testing methods, the
proposed method achieves higher accuracy when test results are noisy. We
perform extensive numerical analysis using a set of real vibration data
collected from the New Carquinez Bridge in California using an 18-sensor
network mounted on the bridge. We also discuss how the features of the Kalman
filter-based group test can be exploited in forming groups and further
improving the detection accuracy.
| arxiv topic:cs.SY |
arxiv_dataset-59101501.04252 | On the thermodynamics of hairy black holes
hep-th gr-qc
We investigate the thermodynamics of a general class of exact 4-dimensional
asymptotically Anti-de Sitter hairy black hole solutions and show that, for a
fixed temperature, there are small and large hairy black holes similar to the
Schwarzschild-AdS black hole. The large black holes have positive specific heat
and so they can be in equilibrium with a thermal bath of radiation at the
Hawking temperature. The relevant thermodynamic quantities are computed by
using the Hamiltonian formalism and counterterm method. We explicitly show that
there are first order phase transitions similar to the Hawking-Page phase
transition.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-59111501.04352 | Solving the Infinite-horizon Constrained LQR Problem using Accelerated
Dual Proximal Methods
math.OC
This work presents an algorithmic scheme for solving the infinite-time
constrained linear quadratic regulation problem. We employ an accelerated
version of a popular proximal gradient scheme, commonly known as the
Forward-Backward Splitting (FBS), and prove its convergence to the optimal
solution in our infinite-dimensional setting. Each iteration of the algorithm
requires only finite memory, is computationally cheap, and makes no use of
terminal invariant sets; hence, the algorithm can be applied to systems of very
large dimensions. The acceleration brings in optimal convergence rates O(1/k^2)
for function values and O(1/k) for primal iterates and renders the proposed
method a practical alternative to model predictive control schemes for setpoint
tracking. In addition, for the case when the true system is subject to
disturbances or modelling errors, we propose an efficient warm-starting
procedure, which significantly reduces the number of iterations when the
algorithm is applied in closed-loop. Numerical examples demonstrate the
approach.
| arxiv topic:math.OC |
arxiv_dataset-59121501.04452 | Secure sequential transmission of quantum information
quant-ph
We propose a quantum communication protocol that can be used to transmit any
quantum state, one party to another via several intermediate nodes, securely on
quantum communication network. The scheme makes use of the sequentially chained
and approximate version of private quantum channels satisfying certain
commutation relation of $n$-qubit Pauli operations. In this paper, we study the
sequential structure, security analysis, and efficiency of the quantum
sequential transmission (QST) protocol in depth.
| arxiv topic:quant-ph |
arxiv_dataset-59131501.04552 | Solving the Klein-Gordon equation using Fourier spectral methods: A
benchmark test for computer performance
cs.PF cs.DC math.NA
The cubic Klein-Gordon equation is a simple but non-trivial partial
differential equation whose numerical solution has the main building blocks
required for the solution of many other partial differential equations. In this
study, the library 2DECOMP&FFT is used in a Fourier spectral scheme to solve
the Klein-Gordon equation and strong scaling of the code is examined on
thirteen different machines for a problem size of 512^3. The results are useful
in assessing likely performance of other parallel fast Fourier transform based
programs for solving partial differential equations. The problem is chosen to
be large enough to solve on a workstation, yet also of interest to solve
quickly on a supercomputer, in particular for parametric studies. Unlike other
high performance computing benchmarks, for this problem size, the time to
solution will not be improved by simply building a bigger supercomputer.
| arxiv topic:cs.PF cs.DC math.NA |
arxiv_dataset-59141501.04652 | Integrating quantum groups over surfaces
math.QA math.AG math.RT
We apply the mechanism of factorization homology to construct and compute
category-valued two-dimensional topological field theories associated to
braided tensor categories, generalizing the $(0,1,2)$-dimensional part of
Crane-Yetter-Kauffman 4D TFTs associated to modular categories. Starting from
modules for the Drinfeld-Jimbo quantum group $U_q(\mathfrak g)$ we obtain in
this way an aspect of topologically twisted 4-dimensional ${\mathcal N}=4$
super Yang-Mills theory, the setting introduced by Kapustin-Witten for the
geometric Langlands program.
For punctured surfaces, in particular, we produce explicit categories which
quantize character varieties (moduli of $G$-local systems) on the surface;
these give uniform constructions of a variety of well-known algebras in quantum
group theory. From the annulus, we recover the reflection equation algebra
associated to $U_q(\mathfrak g)$, and from the punctured torus we recover the
algebra of quantum differential operators associated to $U_q(\mathfrak g)$.
From an arbitrary surface we recover Alekseev's moduli algebras. Our
construction gives an intrinsically topological explanation for well-known
mapping class group symmetries and braid group actions associated to these
algebras, in particular the elliptic modular symmetry (difference Fourier
transform) of quantum $\mathcal D$-modules.
| arxiv topic:math.QA math.AG math.RT |
arxiv_dataset-59151501.04752 | Shape optimization of an electric motor subject to nonlinear
magnetostatics
math.OC
The goal of this paper is to improve the performance of an electric motor by
modifying the geometry of a specific part of the iron core of its rotor. To be
more precise, the objective is to smooth the rotation pattern of the rotor. A
shape optimization problem is formulated by introducing a tracking-type cost
functional to match a desired rotation pattern. The magnetic field generated by
permanent magnets is modeled by a nonlinear partial differential equation of
magnetostatics. The shape sensitivity analysis is rigorously performed for the
nonlinear problem by means of a new shape-Lagrangian formulation adapted to
nonlinear problems.
| arxiv topic:math.OC |
arxiv_dataset-59161501.04852 | Entropy spectrum of (1+1) dimensional stringy black holes
gr-qc
We explore the entropy spectrum of $(1+1)$ dimensional dilatonic stringy
black holes via the adiabatic invariant integral method and the Bohr-Sommerfeld
quantization rule. It is found that the corresponding spectrum depends on black
hole parameters like charge, ADM mass and more interestingly on the dilatonic
field. We calculate the entropy of the present black hole system via the
Euclidean treatment of quantum gravity and study the thermodynamics of the
black hole and find that the system does not undergo any phase transition.
| arxiv topic:gr-qc |
arxiv_dataset-59171501.04952 | Early thermalization, hydrodynamics and energy loss in AdS/CFT
nucl-th gr-qc hep-th
Gauge/gravity duality has provided unprecedented opportunities to study
dynamics in certain strongly coupled gauge theories. This review aims to
highlight several applications to heavy ion collisions including
far-from-equilibrium dynamics, hydrodynamics and jet energy loss at strong
coupling.
| arxiv topic:nucl-th gr-qc hep-th |
arxiv_dataset-59181501.05052 | Theory of angular dispersive imaging hard x-ray spectrographs
physics.optics
A spectrograph is an optical instrument that disperses photons of different
energies into distinct directions and space locations, and images photon
spectra on a position-sensitive detector. Spectrographs consist of collimating,
angular dispersive, and focusing optical elements. Bragg reflecting crystals
arranged in an asymmetric scattering geometry are used as the dispersing
elements. A ray-transfer matrix technique is applied to propagate x-rays
through the optical elements. Several optical designs of hard x-ray
spectrographs are proposed and their performance is analyzed. Spectrographs
with an energy resolution of 0.1 meV and a spectral window of imaging up to a
few tens of meVs are shown to be feasible for inelastic x-ray scattering (IXS)
spectroscopy applications. In another example, a spectrograph with a 1-meV
spectral resolution and 85-meV spectral window of imaging is considered for Cu
K-edge resonant IXS (RIXS).
| arxiv topic:physics.optics |
arxiv_dataset-59191501.05152 | Mirror, mirror on the wall, tell me, is the error small?
cs.CV
Do object part localization methods produce bilaterally symmetric results on
mirror images? Surprisingly not, even though state of the art methods augment
the training set with mirrored images. In this paper we take a closer look into
this issue. We first introduce the concept of mirrorability as the ability of a
model to produce symmetric results in mirrored images and introduce a
corresponding measure, namely the \textit{mirror error} that is defined as the
difference between the detection result on an image and the mirror of the
detection result on its mirror image. We evaluate the mirrorability of several
state of the art algorithms in two of the most intensively studied problems,
namely human pose estimation and face alignment. Our experiments lead to
several interesting findings: 1) Surprisingly, most of state of the art methods
struggle to preserve the mirror symmetry, despite the fact that they do have
very similar overall performance on the original and mirror images; 2) the low
mirrorability is not caused by training or testing sample bias - all algorithms
are trained on both the original images and their mirrored versions; 3) the
mirror error is strongly correlated to the localization/alignment error (with
correlation coefficients around 0.7). Since the mirror error is calculated
without knowledge of the ground truth, we show two interesting applications -
in the first it is used to guide the selection of difficult samples and in the
second to give feedback in a popular Cascaded Pose Regression method for face
alignment.
| arxiv topic:cs.CV |
arxiv_dataset-59201501.05252 | Long-Range Atom-Wall Interactions and Mixing Terms: Metastable Hydrogen
quant-ph physics.atom-ph
We investigate the interaction of metastable 2S hydrogen atoms with a
perfectly conducting wall, including parity-breaking S-P mixing terms (with
full account of retardation). The neighboring 2P_1/2 and 2P_3/2 levels are
found to have a profound effect on the transition from the short-range,
nonrelativistic regime, to the retarded form of the Casimir-Polder interaction.
The corresponding P state admixtures to the metastable 2S state are calculated.
We find the long-range asymptotics of the retarded Casimir-Polder potentials
and mixing amplitudes, for general excited states, including a fully quantum
electrodynamic treatment of the dipole-quadrupole mixing term. The decay width
of the metastable 2S state is roughly doubled even at a comparatively large
distance of 918 atomic units (Bohr radii) from the perfect conductor. The
magnitude of the calculated effects is compared to the unexplained Sokolov
effect.
| arxiv topic:quant-ph physics.atom-ph |
arxiv_dataset-59211501.05352 | Optimizing affinity-based binary hashing using auxiliary coordinates
cs.LG cs.CV math.OC stat.ML
In supervised binary hashing, one wants to learn a function that maps a
high-dimensional feature vector to a vector of binary codes, for application to
fast image retrieval. This typically results in a difficult optimization
problem, nonconvex and nonsmooth, because of the discrete variables involved.
Much work has simply relaxed the problem during training, solving a continuous
optimization, and truncating the codes a posteriori. This gives reasonable
results but is quite suboptimal. Recent work has tried to optimize the
objective directly over the binary codes and achieved better results, but the
hash function was still learned a posteriori, which remains suboptimal. We
propose a general framework for learning hash functions using affinity-based
loss functions that uses auxiliary coordinates. This closes the loop and
optimizes jointly over the hash functions and the binary codes so that they
gradually match each other. The resulting algorithm can be seen as a corrected,
iterated version of the procedure of optimizing first over the codes and then
learning the hash function. Compared to this, our optimization is guaranteed to
obtain better hash functions while being not much slower, as demonstrated
experimentally in various supervised datasets. In addition, our framework
facilitates the design of optimization algorithms for arbitrary types of loss
and hash functions.
| arxiv topic:cs.LG cs.CV math.OC stat.ML |
arxiv_dataset-59221501.05452 | Band edge noise spectroscopy of a magnetic tunnel junction
cond-mat.mes-hall
We propose a conceptually new way to gather information on the electron bands
of buried metal(semiconductor)/insulator interfaces. The bias dependence of low
frequency noise in Fe$_{1-x}$V$_{x}$/MgO/Fe (0 $<$ x $<$ 0.25) tunnel junctions
show clear anomalies at specific applied voltages, reflecting electron
tunneling to the band edges of the magnetic electrodes. The change in magnitude
of these noise anomalies with the magnetic state allows evaluating the degree
of spin mixing between the spin polarized bands at the ferromagnet/insulator
interface. Our results are in qualitative agreement with numerical
calculations.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-59231501.05552 | Estimating the Intrinsic Dimension of Hyperspectral Images Using an
Eigen-Gap Approach
stat.AP cs.CV
Linear mixture models are commonly used to represent hyperspectral datacube
as a linear combinations of endmember spectra. However, determining of the
number of endmembers for images embedded in noise is a crucial task. This paper
proposes a fully automatic approach for estimating the number of endmembers in
hyperspectral images. The estimation is based on recent results of random
matrix theory related to the so-called spiked population model. More precisely,
we study the gap between successive eigenvalues of the sample covariance matrix
constructed from high dimensional noisy samples. The resulting estimation
strategy is unsupervised and robust to correlated noise. This strategy is
validated on both synthetic and real images. The experimental results are very
promising and show the accuracy of this algorithm with respect to
state-of-the-art algorithms.
| arxiv topic:stat.AP cs.CV |
arxiv_dataset-59241501.05652 | Modeling giant extrasolar ring systems in eclipse and the case of
J1407b: sculpting by exomoons?
astro-ph.SR astro-ph.EP astro-ph.IM
The light curve of 1SWASP J140747.93-394542.6, a $\sim$16 Myr old star in the
Sco-Cen OB association, underwent a complex series of deep eclipses that lasted
56 days, centered on April 2007. This light curve is interpreted as the transit
of a giant ring system that is filling up a fraction of the Hill sphere of an
unseen secondary companion, J1407b. We fit the light curve with a model of an
azimuthally symmetric ring system, including spatial scales down to the
temporal limit set by the star's diameter and relative velocity. The best ring
model has 37 rings and extends out to a radius of 0.6 AU (90 million km), and
the rings have an estimated total mass on the order of $100 M_{Moon}$. The ring
system has one clearly defined gap at 0.4 AU (61 million km), which we
hypothesize is being cleared out by a $< 0.8 M_{\oplus}$ exosatellite orbiting
around J1407b. This eclipse and model implies that we are seeing a
circumplanetary disk undergoing a dynamic transition to an
exosatellite-sculpted ring structure and is one of the first seen outside our
Solar system.
| arxiv topic:astro-ph.SR astro-ph.EP astro-ph.IM |
arxiv_dataset-59251501.05752 | On structural properties of trees with minimal atom-bond connectivity
index II
cs.DM math.CO
The {\em atom-bond connectivity (ABC) index} is a degree-based graph
topological index that found chemical applications. The problem of complete
characterization of trees with minimal $ABC$ index is still an open problem.
In~\cite{d-sptmabci-2014}, it was shown that trees with minimal ABC index do
not contain so-called {\em $B_k$-branches}, with $k \geq 5$, and that they do
not have more than four $B_4$-branches. Our main results here reveal that the
number of $B_1$ and $B_2$-branches are also bounded from above by small fixed
constants. Namely, we show that trees with minimal ABC index do not contain
more than four $B_1$-branches and more than eleven $B_2$-branches.
| arxiv topic:cs.DM math.CO |
arxiv_dataset-59261501.05852 | Vacuum Fluctuations of a Scalar Field during Inflation: Quantum versus
Stochastic Analysis
gr-qc astro-ph.CO hep-th
We consider an infrared truncated massless minimally coupled scalar field
with a quartic self-interaction in the locally de Sitter background of an
inflating universe. We compute the two-point correlation function of the scalar
at one and two-loop order applying quantum field theory. The tree-order
correlator at a fixed comoving separation (that is at increasing physical
distance) freezes in to a nonzero value. At a fixed physical distance, it grows
linearly with comoving time. The one-loop correlator, which is the dominant
quantum correction, implies a negative temporal growth in the correlation
function, at this order, at a fixed comoving separation and at a fixed physical
distance. We also obtain quantitative results for variance in space and time of
one and two-loop correlators and infer that the contrast between the vacuum
expectation value and the variance becomes less pronounced when the loop
corrections are included. Finally, we repeat the analysis of the model applying
a stochastic field theory and reach the same conclusions.
| arxiv topic:gr-qc astro-ph.CO hep-th |
arxiv_dataset-59271501.05952 | Astrophysical Constraints on Dark Energy
astro-ph.CO astro-ph.GA gr-qc hep-ph
Dark energy (i.e., a cosmological constant) leads, in the Newtonian
approximation, to a repulsive force which grows linearly with distance and
which can have astrophysical consequences. For example, the dark energy force
overcomes the gravitational attraction from an isolated object (e.g., dwarf
galaxy) of mass $10^7 M_\odot$ at a distance of $~ 23$ kpc. Observable
velocities of bound satellites (rotation curves) could be significantly
affected, and therefore used to measure or constrain the dark energy density.
Here, {\it isolated} means that the gravitational effect of large nearby
galaxies (specifically, of their dark matter halos) is negligible; examples of
isolated dwarf galaxies include Antlia or DDO 1903
| arxiv topic:astro-ph.CO astro-ph.GA gr-qc hep-ph |
arxiv_dataset-59281501.06052 | Macroscopic non-contextuality as a principle for Almost Quantum
Correlations
quant-ph
Quantum mechanics allows only certain sets of experimental results (or
"probabilistic models") for Bell-type quantum non-locality experiments. A
derivation of this set from simple physical or information theoretic principles
would represent an important step forward in our understanding of quantum
mechanics, and this problem has been intensely investigated in recent years.
"Macroscopic locality," which requires the recovery of locality in the limit of
large numbers of trials, is one of several principles discussed in the
literature that place a bound on the set of quantum probabilistic models.
A similar question can also be asked about probabilistic models for the more
general class of quantum contextuality experiments. Here, we extend the
Macroscopic Locality principle to this more general setting, using the
hypergraph approach of Ac\'in, Fritz, Leverrier and Sainz [Comm. Math. Phys.
334(2), 533-628 (2015)], which provides a framework to study both phenomena of
nonlocality and contextuality in a unified manner. We find that the set of
probabilistic models allowed by our Macroscopic Non-Contextuality principle is
equivalent to an important and previously studied set in this formalism, which
is slightly larger than the quantum set. In the particular case of Bell
Scenarios, this set is equivalent to the set of "Almost Quantum" models, which
is of particular interest since the latter was recently shown to satisfy all
but one of the principles that have been proposed to bound quantum
probabilistic models, without being implied by any of them (or even their
conjunction). Our condition is the first characterisation of the almost quantum
set from a simple physical principle.
| arxiv topic:quant-ph |
arxiv_dataset-59291501.06152 | Amenability of groups and semigroups characterized by Configuration
math.FA
In 2005, Abdollahi and Rejali, studied the relations between paradoxical
decompositions and configurations for semigroups. In the present paper, we
introduce another concept of amenability on semigroups and groups which
includes amenability of semigroups and inner-amenability of groups. We have the
previous known results to semigroups and groups satisfying this concept.
| arxiv topic:math.FA |
arxiv_dataset-59301501.06252 | First-principles study of the Kondo physics of a single Pu impurity in a
Th host
cond-mat.str-el
Based on its condensed-matter properties, crystal structure, and metallurgy,
which includes a phase diagram with six allotropic phases, plutonium is one of
the most complicated pure elements in its solid state. Its anomalous
properties, which are indicative of a very strongly correlated state, are
related to its special position in the periodic table, which is at the boundary
between the light actinides that have itinerant 5$f$ electrons and the heavy
actinides that have localized 5$f$ electrons. As a foundational study to probe
the role of local electronic correlations in Pu, we use the local-density
approximation together with a continuous-time quantum Monte Carlo simulation to
investigate the electronic structure of a single Pu atom that is either
substitutionally embedded in the bulk and or adsorbed on the surface of a Th
host. This is a simpler case than the solid phases of Pu metal, which must also
include the interactions between Pu 5$f$ electrons on different Pu atoms. For
the Pu impurity atom we have found a Kondo resonance peak, which is an
important signature of electronic correlations, in the local density of states
around the Fermi energy. Furthermore, we show that the peak width of this
resonance is narrower for Pu atoms at the surface of Th than for those in the
bulk due to a weakened Pu 5$f$-ligand hybridization at the surface.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-59311501.06352 | The Link Between Morphology and Structure of Brightest Cluster Galaxies:
Automatic Identification of cDs
astro-ph.GA
We study a large sample of 625 low-redshift brightest cluster galaxies (BCGs)
and link their morphologies to their structural properties. We derive visual
morphologies and find that ~57% of the BCGs are cD galaxies, ~13% are
ellipticals, and ~21% belong to the intermediate classes mostly between E and
cD. There is a continuous distribution in the properties of the BCG's
envelopes, ranging from undetected (E class) to clearly detected (cD class),
with intermediate classes (E/cD and cD/E) showing the increasing degrees of the
envelope presence. A minority (~7%) of BCGs have disk morphologies, with
spirals and S0s in similar proportions, and the rest (~2%) are mergers. After
carefully fitting the galaxies light distributions by using one-component
(Sersic) and two-component (Sersic+Exponential) models, we find a clear link
between the BCGs morphologies and their structures and conclude that a
combination of the best-fit parameters derived from the fits can be used to
separate cD galaxies from non-cD BCGs. In particular, cDs and non-cDs show very
different distributions in the $R_e$--$RFF$ plane, where $R_e$ is the effective
radius and $RFF$ (the residual flux fraction) measures the proportion of the
galaxy flux present in the residual images after subtracting the models. In
general, cDs have larger $R_e$ and $RFF$ values than ellipticals. Therefore we
find, in a statistically robust way, a boundary separating cD and non-cD BCGs
in this parameter space. BCGs with cD morphology can be selected with
reasonably high completeness (~75%) and low contamination (~20%). This
automatic and objective technique can be applied to any current or future BCG
sample with good quality images.
| arxiv topic:astro-ph.GA |
arxiv_dataset-59321501.06452 | A Hofmann-Mislove Theorem for Scott open sets
math.LO
We consider the intersection map on the family of non-empty
$\omega$-Scott-open sets of the lattice of opens of a topological space. We
prove that in a certain class of topological spaces the intersection map forms
a continuous retraction onto the space of countably compact subsets of the
space equipped with (the sequentialisation of) the upper Vietoris topology.
This class consists of all sequential spaces which are sequentially Hausdorff.
| arxiv topic:math.LO |
arxiv_dataset-59331501.06552 | The Hidden Geometry of Attention Diffusion
physics.soc-ph
We propose a geometric model to quantify the dynamics of attention in online
communities. Using clicks as a proxy of attention, we find that the diffusion
of collective attention in Web forums and news sharing sites forms
time-invariant "fields" whose density vary solely with distance from the center
of the fields that represents the input of attention from the physical world.
As time goes by, old information pieces are pushed farther from the center by
new pieces, receive fewer and fewer clicks, and eventually become invisible in
the virtual world. The discovered "attention fields" not only explain the fast
decay of attention to information pieces, but also predict the accelerating
growth of clicks against the active user population, which is a universal
pattern relevant to the economics of scales of online interactions.
| arxiv topic:physics.soc-ph |
arxiv_dataset-59341501.06652 | Intranight optical variability of radio-quiet BL Lacertae objects
astro-ph.GA astro-ph.HE
Aims: Intranight variation (or microvariation) is a common phenomenon of
radio-loud BL Lac objects. However, it is not clear whether the recently found
radio-quiet BL Lac objects have the same properties. The occurrence rate of
intranight variation is helpful in distinguishing the mechanism of the
continuum of radio-quiet BL Lac objects.
Methods: We conducted a photometric monitoring of 8 radio-quiet BL Lac
objects by the Xinglong 2.16m and Lijiang 2.4m telescopes. The differential
light curves are calculated between each target and two comparison stars. To
quantify the variation, the significance of variation is examined by a scaled
$F$-test.
Results: No significant variation is found in the 11 sessions of light curves
of 8 radio-quiet BL Lac objects (one galactic source is excluded). The lack of
microvariation in radio-quiet BL Lac objects is consistent with the detection
rate of microvariation in normal radio-quiet AGNs, but much lower than for
radio-loud AGNs. This result indicates that the continua of the radio-quiet BL
Lac objects are not dominated by jets that will induce frequent
microvariations.
| arxiv topic:astro-ph.GA astro-ph.HE |
arxiv_dataset-59351501.06752 | On the irrationality measure of certain numbers
math.NT
The paper presents upper estimates for the irrationality measure and the
non-quadraticity measure for the numbers
$\alpha_k=\sqrt{2k+1}\ln\frac{\sqrt{2k+1}-1}{\sqrt{2k+1}+1}, \ k\in\mathbb N.$
| arxiv topic:math.NT |
arxiv_dataset-59361501.06852 | Development and Analysis of a Block-Preconditioner for the Phase-Field
Crystal Equation
physics.comp-ph math.NA
We develop a preconditioner for the linear system arising from a finite
element discretization of the Phase Field Crystal (PFC) equation. The PFC model
serves as an atomic description of crystalline materials on diffusive time
scales and thus offers the opportunity to study long time behaviour of
materials with atomic details. This requires adaptive time stepping and
efficient time discretization schemes, for which we use an embedded Rosenbrock
scheme. To resolve spatial scales of practical relevance, parallel algorithms
are also required, which scale to large numbers of processors. The developed
preconditioner provides such a tool. It is based on an approximate
factorization of the system matrix and can be implemented efficiently. The
preconditioner is analyzed in detail and shown to speed up the computation
drastically.
| arxiv topic:physics.comp-ph math.NA |
arxiv_dataset-59371501.06952 | Fast Bayesian Inference for Exoplanet Discovery in Radial Velocity Data
astro-ph.IM astro-ph.EP physics.data-an stat.AP
Inferring the number of planets $N$ in an exoplanetary system from radial
velocity (RV) data is a challenging task. Recently, it has become clear that RV
data can contain periodic signals due to stellar activity, which can be
difficult to distinguish from planetary signals. However, even doing the
inference under a given set of simplifying assumptions (e.g. no stellar
activity) can be difficult. It is common for the posterior distribution for the
planet parameters, such as orbital periods, to be multimodal and to have other
awkward features. In addition, when $N$ is unknown, the marginal likelihood (or
evidence) as a function of $N$ is required. Rather than doing separate runs
with different trial values of $N$, we propose an alternative approach using a
trans-dimensional Markov Chain Monte Carlo method within Nested Sampling. The
posterior distribution for $N$ can be obtained with a single run. We apply the
method to $\nu$ Oph and Gliese 581, finding moderate evidence for additional
signals in $\nu$ Oph with periods of 36.11 $\pm$ 0.034 days, 75.58 $\pm$ 0.80
days, and 1709 $\pm$ 183 days; the posterior probability that at least one of
these exists is 85%. The results also suggest Gliese 581 hosts many (7-15)
"planets" (or other causes of other periodic signals), but only 4-6 have well
determined periods. The analysis of both of these datasets shows phase
transitions exist which are difficult to negotiate without Nested Sampling.
| arxiv topic:astro-ph.IM astro-ph.EP physics.data-an stat.AP |
arxiv_dataset-59381501.07052 | Single and double spin asymmetries for deeply virtual Compton scattering
measured with CLAS and a longitudinally polarized proton target
hep-ex nucl-ex
Single-beam, single-target, and double-spin asymmetries for hard exclusive
photon production on the proton $\vec{e}\vec{p} \to e' p'\gamma$ are presented.
The data were taken at Jefferson Lab using the CLAS detector and a
longitudinally polarized ${}^{14}$NH$_3$ target. The three asymmetries were
measured in 165 4-dimensional kinematic bins, covering the widest kinematic
range ever explored simultaneously for beam and target-polarization observables
in the valence quark region. The kinematic dependences of the obtained
asymmetries are discussed and compared to the predictions of models of
Generalized Parton Distributions. The measurement of three DVCS spin
observables at the same kinematic points allows a quasi-model-independent
extraction of the imaginary parts of the $H$ and $\tilde{H}$ Compton Form
Factors, which give insight into the electric and axial charge distributions of
valence quarks in the proton.
| arxiv topic:hep-ex nucl-ex |
arxiv_dataset-59391501.07152 | Compatibility fans for graphical nested complexes
math.CO math.MG
Graph associahedra are natural generalizations of the classical associahedra.
They provide polytopal realizations of the nested complex of a graph $G$,
defined as the simplicial complex whose vertices are the tubes (i.e. connected
induced subgraphs) of $G$ and whose faces are the tubings (i.e. collections of
pairwise nested or non-adjacent tubes) of $G$. The constructions of M. Carr and
S. Devadoss, of A. Postnikov, and of A. Zelevinsky for graph associahedra are
all based on the nested fan which coarsens the normal fan of the permutahedron.
In view of the combinatorial and geometric variety of simplicial fan
realizations of the classical associahedra, it is tempting to search for
alternative fans realizing graphical nested complexes.
Motivated by the analogy between finite type cluster complexes and graphical
nested complexes, we transpose in this paper S. Fomin and A. Zelevinsky's
construction of compatibility fans from the former to the latter setting. For
this, we define a compatibility degree between two tubes of a graph $G$. Our
main result asserts that the compatibility vectors of all tubes of $G$ with
respect to an arbitrary maximal tubing on $G$ support a complete simplicial fan
realizing the nested complex of $G$. In particular, when the graph $G$ is
reduced to a path, our compatibility degree lies in $\{-1,0,1\}$ and we recover
F. Santos' Catalan many simplicial fan realizations of the associahedron.
| arxiv topic:math.CO math.MG |
arxiv_dataset-59401501.07252 | In-plane anisotropy effect on critical transition field in nanogranular
films with perpendicular anisotropy
cond-mat.mes-hall
The influence of the in-plane anisotropy on the magnetization of a
nanogranular film with perpendicular anisotropy has been studied. It is shown
that if a magnetic field is tilted with respect to the film normal, a critical
transition from the inhomogeneous magnetic state of granules with noncollinear
directions of their moments to the homogeneous one with parallel orientation of
granular magnetic moments takes place. The in-plane anisotropy is found to
affect the angular dependence of the critical field. The ensemble of oriented
biaxial particles is theoretically described in the double-well potential
approximation. Despite the biaxial magnetic anisotropy of particles, their
ensemble, if in the inhomogeneous state, is divided into two subensembles, with
the magnetic moments of particles being collinear in each of them. In the
critical field, a transition from the inhomogeneous state with two subensembles
into the homogeneous one takes place. The results of theoretical calculations
are compared with experimental data for a nanogranular Co/Al2On film with
perpendicular anisotropy containing 74.5 at.% Co, which exceeds the percolation
threshold. The magnetic moment of this film is a sum of two contributions: from
nanogranules with biaxial anisotropy and a phase forming the percolation
cluster. The magnetic properties of nanogranules, whose contribution is
separated from the total film magnetization, agree well with the calculation
data.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-59411501.07352 | High Temperature Enthalpy Increment and Thermodynamic Functions of ZrCo:
An Experimental and Theoretical Study
cond-mat.mtrl-sci
The ZrCo intermetallic was proposed as tritium storage material in the
International Thermonuclear Experimental Reactors (ITER) project. The
thermodynamic properties of ZrCo intermetallic were investigated both
experimentally and theoretically to determine its applicability for the storage
of hydrogen isotopes. The enthalpy increments of ZrCo were measured using a
high temperature inverse drop calorimeter in the temperature range 645-1500 K.
A set of thermodynamic functions such as entropy, Gibbs energy function, heat
capacity, Gibbs energy and enthalpy values for ZrCo were calculated using the
data obtained in this study. The polynomial expression of enthalpy increments
and heat capacity obtained for ZrCo(s) in the temperature range 642-1497 K are
given as: H(T) - H(298.15 K) (J/mol) = 25.682x(T/K) + 29.804x10e-4 (T/K)**2+
2.1864x10e+5 (K/T) - 8655.5 Cp (J/K/mol) =25.682 + 5.916x10e-3 (T/K) -
2.1864x10e+5 (K/T)**2 The enthalpy of formation of ZrCo at 0 K was calculated
as -55 kJ mol-1 using the ab-initio method. The entropy (S) and specific heat
capacities (Cv and Cp) of ZrCo were also computed using Debye-Gr\"uneisen
quasi-harmonic approximation. A good agreement between the experimental and
theoretically calculated values of specific heat (CP) and entropy was obtained.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-59421501.07452 | Purcell factor of Mie resonators featuring electric and magnetic modes
physics.optics
We present a modal approach to compute the Purcell factor in Mie resonators
exhibiting both electric and magnetic resonances. The analytic expressions of
the normal modes are used to calculate the effective volumes. We show that
important features of the effective volume can be predicted thanks to the
translation-addition coefficients of a displaced dipole. Using our formalism,
it is easy to see that, in general, the Purcell factor of Mie resonators is not
dominated by a single mode, but rather by a large superposition. Finally we
consider a silicon resonator homogeneously doped with electric dipolar
emitters, and we show that the average electric Purcell factor dominates over
the magnetic one.
| arxiv topic:physics.optics |
arxiv_dataset-59431501.07552 | Teichm\"uller harmonic map flow from cylinders
math.AP math.DG
We define a geometric flow that is designed to change surfaces of cylindrical
type spanning two disjoint boundary curves into solutions of the
Douglas-Plateau problem of finding minimal surfaces with given boundary curves.
We prove that also in this new setting and for arbitrary initial data,
solutions of the Teichm\"uller harmonic map flow exist for all times.
Furthermore, for solutions for which a three-point-condition does not
degenerate as $t\to\infty$, we show convergence along a sequence $t_i\to\infty$
to a critical point of the area given either by a minimal cylinder or by two
minimal discs spanning the given boundary curves.
| arxiv topic:math.AP math.DG |
arxiv_dataset-59441501.07652 | The QCD Equation of State
hep-lat
Results for the equation of state in 2+1 flavor QCD at zero net baryon
density using the Highly Improved Staggered Quark (HISQ) action by the HotQCD
collaboration are presented. The strange quark mass was tuned to its physical
value and the light (up/down) quark masses fixed to $m_l = 0.05m_s$
corresponding to a pion mass of 160 MeV in the continuum limit. Lattices with
temporal extent $N_t=6$, 8, 10 and 12 were used. Since the cutoff effects for
$N_t>6$ were observed to be small, reliable continuum extrapolations of the
lattice data for the phenomenologically interesting temperatures range $130
\mathord{\rm MeV} < T < 400 \mathord{\rm MeV}$ could be performed. We discuss
statistical and systematic errors and compare our results with other published
works.
| arxiv topic:hep-lat |
arxiv_dataset-59451501.07752 | Ground states for a coupled nonlinear Schr\"odinger system
math.AP
We study the existence of ground states for the coupled Schr\"odinger system
\begin{equation} \label{ellipticabstract} \left\{ \begin{array}{llll} -\Delta
u+u&=&|u|^{2q-2}u+b|v|^q|u|^{q-2}u\\ -\Delta
v+\omega^2v&=&|v|^{2q-2}v+b|u|^q|v|^{q-2}v \end{array}\right. \end{equation} in
$\mathbf{R}^n$, for $\omega \geq 1$, $b>0$ (the so-called "attractive case")
and $q>1$ ($q<\frac n{n-2}$ if $n\geq 3$). We improve for several ranges of
$(q,n,\omega)$ the known results concerning the existence of positive ground
state solutions with non-trivial components. In particular, we prove that for
$1<q<2$ such ground states exist in all dimensions and for all values of
$\omega$, which constitutes a drastic change of behaviour with respect to the
case $q\geq 2$.
Furthermore, in the one-dimensional case $n=1$, we improve the results
present in the literature for $q>2$.
| arxiv topic:math.AP |
arxiv_dataset-59461501.07852 | Alignment and resolution studies of a MARS scanner
physics.ins-det
The MARS scanner is designed for the x-ray spectroscopic study of samples
with the aid of computer tomography methods. Computer tomography allows the
reconstruction of slices of an investigated sample using a set of shadow
projections obtained for different angles. Projections in the MARS scanner are
produced using a cone x-ray beam geometry. Correct reconstruction in this
scheme requires precise knowledge of several geometrical parameters of a
tomograph, such as displacement of a rotation axis, x-ray source position with
respect to a camera, and camera inclinations. Use of inaccurate parameters
leads to a poor sample reconstruction. Non-ideal positioning of camera, x-ray
source and cylindrical rotating frame (gantry) itself on which these parts are
located, leads to the need for tomograph alignment. In this note we describe
the alignment procedure that was used to get different geometrical corrections
for the reconstruction. Also, several different estimations of the final
spatial resolution for reconstructed images are presented.
| arxiv topic:physics.ins-det |
arxiv_dataset-59471502.0004 | Multiple-pulse lasing from an optically induced harmonic confinement in
a highly photoexcited microcavity
cond-mat.mes-hall physics.optics quant-ph
We report the observation of macroscopic harmonic states in an optically
induced confinement in a highly photoexcited semiconductor microcavity at room
temperature. The spatially photomodulated refractive index changes result in
the visualization of harmonic states in a micrometer-scale optical potential at
quantized energies up to 4 meV even in the weak-coupling plasma limit. We
characterize the time evolution of the harmonic states directly from the
consequent pulse radiation and identify sequential multiple $\sim$10 ps pulse
lasing with different emitting angles and frequencies.
| arxiv topic:cond-mat.mes-hall physics.optics quant-ph |
arxiv_dataset-59481502.0014 | Regression version of the Matsumoto-Yor type characterization of the
gamma and Kummer distributions
math.PR math.ST stat.TH
In this paper we study a Matsumoto-Yor type property for the gamma and Kummer
inde- pendent variables discovered in Koudou and Vallois (2012). We prove that
constancy of regressions of U = (1 + 1/(X + Y ))=(1 + 1/X) given V = X + Y and
of 1/U given V , where X and Y are indepen- dent and positive random variables,
characterizes the gamma and Kummer distributions. This result completes
characterizations by independence of U and V obtained, under smoothness
assumptions for densities, in Koudou and Vallois (2011, 2012). Since we work
with differential equations for the Laplace transforms, no density assumptions
are needed.
| arxiv topic:math.PR math.ST stat.TH |
arxiv_dataset-59491502.0024 | A Comprehensive Study of Broad Absorption Line Quasars: I. Prevalence of
HeI* Absorption Line Multiplets in Low-Ionization Objects
astro-ph.GA astro-ph.CO
Neutral Helium multiplets, HeI*3189,3889,10830 are very useful diagnostics to
the geometry and physical conditions of the absorbing gas in quasars. So far
only a handful of HeI* detections have been reported. Using a newly developed
method, we detected HeI*3889 absorption line in 101 sources of a well-defined
sample of 285 MgII BAL quasars selected from the SDSS DR5. This has increased
the number of HeI* BAL quasars by more than one order of magnitude. We further
detected HeI*3189 in 50% (52/101) quasars in the sample. The detection fraction
of HeI* BALs in MgII BAL quasars is about 35% as a whole, and increases
dramatically with increasing spectral signal-to-noise ratios, from 18% at S/N
<= 10 to 93% at S/N >= 35. This suggests that HeI* BALs could be detected in
most MgII LoBAL quasars, provided spectra S/N is high enough. Such a
surprisingly high HeI* BAL fraction is actually predicted from photo-ionization
calculations based on a simple BAL model. The result indicates that HeI*
absorption lines can be used to search for BAL quasars at low-z, which cannot
be identified by ground-based optical spectroscopic survey with commonly seen
UV absorption lines. Using HeI*3889, we discovered 19 BAL quasars at z<0.3 from
available SDSS spectral database. The fraction of HeI* BAL quasars is similar
to that of LoBAL objects.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-59501502.0034 | Lattices in potentially semi-stable representations and weak
$(\varphi,\hat{G})$-modules
math.NT
Let $p$ be a prime number and $r$ a non-negative integer. In this paper, we
prove that there exists an anti-equivalence between the category of weak
$(\varphi,\hat{G})$-modules of height $r$ and a certain subcategory of the
category of Galois stable lattices in potentially semi-stable $p$-adic
representations with Hodge-Tate weights in $[0,r]$. This gives an answer to a
Tong Liu's question about the essential image of a functor on weak
$(\varphi,\hat{G})$-modules. For a proof, following Liu's methods, we construct
linear algebraic data which classify lattices in potentially semi-stable
representations.
| arxiv topic:math.NT |
arxiv_dataset-59511502.0044 | Type and cotype of multilinear operators
math.FA
The aim of this paper is to start the study of multilinear generalizations of
the classical ideals of linear operators of type $p$ and cotype $q$. As a first
step in a theory we believe will be long and fruitful, we propose a notion of
type and cotype of multilinear operators and the resulting classes of such
mappings are studied in the setting of the theory of Banach/quasi-Banach ideals
of multilinear operators. Distinctions between the linear and the multilinear
theories are pointed out, typical multilinear features of the theory are
emphasized and many illustrative examples are provided. The classes we
introduce are related to the multi-ideals generated by the linear ideals of
operators of some type/cotype and are proved to be maximal and Aron-Berner
stable.
| arxiv topic:math.FA |
arxiv_dataset-59521502.0054 | Multichannel one-to-two transition amplitudes in a finite volume
hep-lat hep-ph nucl-th
We derive a model-independent expression for finite-volume matrix elements.
Specifically, we present a relativistic, non-perturbative analysis of the
matrix element of an external current between a one-scalar in-state and a
two-scalar out-state. Our result, which is valid for energies below
higher-particle inelastic thresholds, generalizes the Lellouch-Luscher formula
in two ways: we allow the external current to inject arbitrary momentum into
the system and we allow for the final state to be composed an arbitrary number
of strongly coupled two-particle states with arbitrary partial waves (including
partial-wave mixing induced by the volume). We also illustrate how our general
result can be applied to some key examples, such as heavy meson decays and
meson photo production. Finally, we point out complications that arise
involving unstable resonance states, such as $B\rightarrow K^*\ell^+\ell^-$
when staggered or mixed-action/partially-quenched calculations are performed.
| arxiv topic:hep-lat hep-ph nucl-th |
arxiv_dataset-59531502.0064 | ALMA constraints on the faint millimetre source number counts and their
contribution to the cosmic infrared background
astro-ph.GA
We have analysed 18 ALMA continuum maps in Bands 6 and 7, with rms down to
7.8$\mu$Jy, to derive differential number counts down to 60$\mu$Jy and
100$\mu$Jy at $\lambda=$1.3 mm and $\lambda=$1.1 mm, respectively. The area
covered by the combined fields is $\rm 9.5\times10^{-4}deg^2$ at 1.1mm and $\rm
6.6\times10^{-4}deg^{2}$ at 1.3mm. We improved the source extraction method by
requiring that the dimension of the detected sources be consistent with the
beam size. This method enabled us to remove spurious detections that have
plagued the purity of the catalogues in previous studies. We detected 50 faint
sources with S/N$>$3.5 down to 60$\mu$Jy, hence improving the statistics by a
factor of four relative to previous studies. The inferred differential number
counts are $\rm dN/d(Log_{10}S)=1\times10^5~deg^2$ at a 1.1 mm flux $S_{\lambda
= 1.1~mm} = 130~\mu$Jy, and $\rm dN/d(Log_{10}S)=1.1\times10^5~deg^2$ at a 1.3
mm flux $\rm S_{\lambda = 1.3~mm} = 60~\mu$Jy. At the faintest flux limits,
i.e. 30$\mu$Jy and 40$\mu$Jy, we obtain upper limits on the differential number
counts of $\rm dN/d(Log_{10}S) < 7\times10^5~deg^2$ and $\rm
dN/d(Log_{10}S)<3\times10^5~deg^2$, respectively. Our results provide a new
lower limit to CIB intensity of 17.2${\rm Jy\ deg^{-2}}$ at 1.1mm and of
12.9${\rm Jy\ deg^{-2}}$ at 1.3mm. Moreover, the flattening of the integrated
number counts at faint fluxes strongly suggests that we are probably close to
the CIB intensity. Our data imply that galaxies with SFR$<40~M_{\odot}/yr$
certainly contribute less than 50% to the CIB while more than 50% of the CIB
must be produced by galaxies with $\rm SFR>40~M_{\odot}/yr$. The differential
number counts are in nice agreement with recent semi-analytical models of
galaxy formation even as low as our faint fluxes. Consequently, this supports
the galaxy evolutionary scenarios and assumptions made in these models.
| arxiv topic:astro-ph.GA |
arxiv_dataset-59541502.0074 | Schr\"odinger geometries arising from Yang-Baxter deformations
hep-th gr-qc math-ph math.MP nlin.SI
We present further examples of the correspondence between solutions of type
IIB supergravity and classical $r$-matrices satisfying the classical
Yang-Baxter equation (CYBE). In the previous works, classical $r$-matrices have
been composed of generators of only one of either $\mathfrak{so}(2,4)$ or
$\mathfrak{so}(6)$. In this paper, we consider some examples of $r$-matrices
with both of them. The $r$-matrices of this kind contain (generalized)
Schr\"odinger spacetimes and gravity duals of dipole theories. It is known that
the generalized Schr\"odinger spacetimes can also be obtained via a certain
class of TsT transformations called null Melvin twists. The metric and NS-NS
two-form are reproduced by following the Yang-Baxter sigma-model description.
| arxiv topic:hep-th gr-qc math-ph math.MP nlin.SI |
arxiv_dataset-59551502.0084 | Tree pressure for hyperbolic and non-exceptional upper semi-continuous
potentials
math.DS
In this note, we investigate the tree pressure for multi-modal interval maps
with a certain class of hyperbolic and non-exceptional upper semi-continuous
functions. In particular, we obtain a generalized version of Corollary 2.2 in
the paper \cite{LRL14} by Li and Rivera-Letelier. This property will be used to
prove the existence of a conformal measure for the geometric potential in the
negative spectrum.
| arxiv topic:math.DS |
arxiv_dataset-59561502.0094 | Phase Diagrams of Systems of 2 and 3 levels in the presence of a
Radiation Field
quant-ph
We study the structure of the phase diagram for systems consisting of 2- and
3- level particles dipolarly interacting with a 1-mode electromagnetic field,
inside a cavity, paying particular attention to the case of a finite number of
particles, and showing that the divergences that appear in other treatments are
a consequence of the mathematical approximations employed and can be avoided by
studying the system in an exact manner quantum-mechanically or via a
catastrophe formalism with variational trial states that satisfy the symmetries
of the appropriate Hamiltonians. These variational states give an excellent
approximation not only to the exact quantum phase space, but also to the energy
spectrum and the expectation values of the atomic and field operators.
Furthermore, they allow for analytic expressions in many of the cases studied.
We find the loci of the transitions in phase space from one phase to the other,
and the order of the quantum phase transitions are determined explicitly for
each of the configurations, with and without detuning. We also derive the
critical exponents for the various systems, and the phase structure at the
triple point present in the {\Xi}-configuration of 3-level systems is studied.
| arxiv topic:quant-ph |
arxiv_dataset-59571502.0104 | Cox rings of du Val singularities
math.AG
In this note we introduce Cox rings of singularities and explicitly compute
them in the case of du Val singularities
$\mathbb{D}_n,\mathbb{E}_6,\mathbb{E}_7$ and $\mathbb{E}_8$.
| arxiv topic:math.AG |
arxiv_dataset-59581502.0114 | Ultimate Informational Capacity of a Volume Photosensitive Media
cond-mat.mtrl-sci physics.optics
The ultimate information capacity of a three-dimensional hologram for the
case of an optimal use of the dynamic range of a storage medium, number of
pages, the readout conditions is considered. The volume hologram is regarded as
an object of the information theory. For the first time the formalism of the
reciprocal lattice has been introduced in order to estimate the informational
properties of the hologram. The diffraction-limited holographic recording is
analyzed in the framework of the reciprocal lattice formalism. Calculations of
the information capacity of a three-dimensional hologram involve analysis of a
set of multiplexed holograms, each of which has a finite signal-to-noise ratio
determined by the dynamic range of the holographic medium and the geometry of
recording and readout. An optimal number of pages that provides a maxi-mum
information capacity at angular multiplexing is estimated.
| arxiv topic:cond-mat.mtrl-sci physics.optics |
arxiv_dataset-59591502.0124 | A Predictive Framework for Cyber Security Analytics using Attack Graphs
cs.CR
Security metrics serve as a powerful tool for organizations to understand the
effectiveness of protecting computer networks. However majority of these
measurement techniques don't adequately help corporations to make informed risk
management decisions. In this paper we present a stochastic security framework
for obtaining quantitative measures of security by taking into account the
dynamic attributes associated with vulnerabilities that can change over time.
Our model is novel as existing research in attack graph analysis do not
consider the temporal aspects associated with the vulnerabilities, such as the
availability of exploits and patches which can affect the overall network
security based on how the vulnerabilities are interconnected and leveraged to
compromise the system. In order to have a more realistic representation of how
the security state of the network would vary over time, a nonhomogeneous model
is developed which incorporates a time dependent covariate, namely the
vulnerability age. The daily transition-probability matrices are estimated
using Frei's Vulnerability Lifecycle model. We also leverage the trusted CVSS
metric domain to analyze how the total exploitability and impact measures
evolve over a time period for a given network.
| arxiv topic:cs.CR |
arxiv_dataset-59601502.0134 | Competing Abelian and non-Abelian topological orders in $\nu = 1/3+1/3$
quantum Hall bilayers
cond-mat.str-el
Bilayer quantum Hall systems, realized either in two separated wells or in
the lowest two sub-bands of a wide quantum well, provide an experimentally
realizable way to tune between competing quantum orders at the same filling
fraction. Using newly developed density matrix renormalization group techniques
combined with exact diagonalization, we return to the problem of quantum Hall
bilayers at filling $\nu = 1/3 + 1/3$. We first consider the Coulomb
interaction at bilayer separation $d$, bilayer tunneling energy
$\Delta_\textrm{SAS}$, and individual layer width $w$, where we find a phase
diagram which includes three competing Abelian phases: a bilayer-Laughlin phase
(two nearly decoupled $\nu = 1/3$ layers); a bilayer-spin singlet phase; and a
bilayer-symmetric phase. We also study the order of the transitions between
these phases. A variety of non-Abelian phases have also been proposed for these
systems. While absent in the simplest phase diagram, by slightly modifying the
interlayer repulsion we find a robust non-Abelian phase which we identify as
the "interlayer-Pfaffian" phase. In addition to non-Abelian statistics similar
to the Moore-Read state, it exhibits a novel form of bilayer-spin charge
separation. Our results suggest that $\nu = 1/3 + 1/3$ systems merit further
experimental study.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-59611502.0144 | Constraints on non-standard flavor-dependent interactions from
Superkamiokande and Hyperkamiokande
hep-ph
We investigate the constraint on the flavor-dependent neutral current
Non-Standard Interactions in propagation from atmospheric neutrino experiments
Superkamiokande and Hyperkamiokande. With the ansatz where the parameters which
have strong constraints from other experiments are neglected, we show how these
experiments put constraints on the remaining parameters of the Non-Standard
Interactions.
| arxiv topic:hep-ph |
arxiv_dataset-59621502.0154 | Semantic Embedding Space for Zero-Shot Action Recognition
cs.CV
The number of categories for action recognition is growing rapidly. It is
thus becoming increasingly hard to collect sufficient training data to learn
conventional models for each category. This issue may be ameliorated by the
increasingly popular 'zero-shot learning' (ZSL) paradigm. In this framework a
mapping is constructed between visual features and a human interpretable
semantic description of each category, allowing categories to be recognised in
the absence of any training data. Existing ZSL studies focus primarily on image
data, and attribute-based semantic representations. In this paper, we address
zero-shot recognition in contemporary video action recognition tasks, using
semantic word vector space as the common space to embed videos and category
labels. This is more challenging because the mapping between the semantic space
and space-time features of videos containing complex actions is more complex
and harder to learn. We demonstrate that a simple self-training and data
augmentation strategy can significantly improve the efficacy of this mapping.
Experiments on human action datasets including HMDB51 and UCF101 demonstrate
that our approach achieves the state-of-the-art zero-shot action recognition
performance.
| arxiv topic:cs.CV |
arxiv_dataset-59631502.0164 | Spaces of smooth embeddings and configuration categories
math.AT
In the homotopical study of spaces of smooth embeddings, the functor calculus
method (Goodwillie-Klein-Weiss manifold calculus) has opened up important
connections to operad theory. Using this and a few simplifying observations, we
arrive at an operadic description of the obstructions to deforming smooth
immersions into smooth embeddings. We give an application which in some
respects improves on recent results of Arone-Turchin and Dwyer-Hess concerning
high-dimensional variants of spaces of long knots.
| arxiv topic:math.AT |
arxiv_dataset-59641502.0174 | Effect of charging on CdSe/CdS dot-in-rods single-photon emission
quant-ph cond-mat.mes-hall
The photon statistics of CdSe/CdS dot-in-rods nanocrystals is studied with a
method involving post-selection of the photon detection events based on the
photoluminescence count rate. We show that flickering between two states needs
to be taken into account to interpret the single-photon emission properties.
With post-selection we are able to identify two emitting states: the exciton
and the charged exciton (trion), characterized by different lifetimes and
different second order correlation functions. Measurements of the second order
autocorrelation function at zero delay with post- selection shows a degradation
of the single photon emission for CdSe/CdS dot-in-rods in a charged state that
we explain by deriving the neutral and charged biexciton quantum yields.
| arxiv topic:quant-ph cond-mat.mes-hall |
arxiv_dataset-59651502.0184 | Perturbations of time optimal control problems for a class of abstract
parabolic systems
math.OC
In this work we study the asymptotic behavior of the solutions of a class of
abstract parabolic time optimal control problems when the generators converge,
in an appropriate sense, to a given strictly negative operator. Our main
application to PDEs systems concerns the behavior of optimal time and of the
associated optimal controls for parabolic equations with highly oscillating
coefficients, as we encounter in homogenization theory. Our main results assert
that, provided that the target is a closed ball centered at the origin and of
positive radius, the solutions of the time optimal control problems for the
systems with oscillating coefficients converge, in the usual norms, to the
solution of the corresponding problem for the homogenized system. In order to
prove our main theorem, we provide several new results, which could be of a
broader interest, on time and norm optimal control problems.
| arxiv topic:math.OC |
arxiv_dataset-59661502.0194 | Elko and mass dimension one field of spin one half: causality and Fermi
statistics
hep-th hep-ph math-ph math.MP
We review how Elko arise as an extension of complex valued four-component
Majorana spinors. This is followed by a discussion that constrains certain
elements of phase freedom. A proof is reviewed that unambiguously establishes
that Elko, and for that matter the indicated Majorana spinors, cannot satisfy
Dirac equation. They, however do, as they must, satisfy spinorial Klein-Gordon
equation. We then introduce a quantum field with Elko as its expansion
coefficients and show that it is causal, satisfies Fermi statistics, and then
refer to the existing literature to remind that its mass dimensionally is one.
We conclude by providing an up-to-date bibliography on the subject.
| arxiv topic:hep-th hep-ph math-ph math.MP |
arxiv_dataset-59671502.0204 | The Pseudo-zodi Problem for Edge-on Planetary Systems
astro-ph.SR astro-ph.EP
Future direct observations of extrasolar Earth-sized planets in the habitable
zone could be hampered by a worrisome source of noise, starlight-reflecting
exozodiacal dust. Mid-infrared surveys are currently underway to constrain the
amount of exozodiacal dust in the habitable zones around nearby stars. However,
at visible wavelengths another source of dust, invisible to these surveys, may
dominate over exozodiacal dust. For systems observed near edge-on, a cloud of
dust with face-on optical depth 10^-7 beyond ~5 AU can mimic the surface
brightness of a cloud of exozodiacal dust with equal optical depth if the dust
grains are sufficiently forward-scattering. We posit that dust migrating inward
from cold debris belts via Poynting-Robertson drag could produce this
"pseudo-zodiacal" effect, potentially making it ~50% as common as exozodiacal
clouds. We place constraints on the disk radii and scattering phase function
required to produce the effect.
| arxiv topic:astro-ph.SR astro-ph.EP |
arxiv_dataset-59681502.0214 | Notes on Central Extensions
math.GR math.NT math.RT
These are the notes for some lectures given by this author at Harish-Chandra
Research Institute, Allahabad in March 2014 for a workshop on Schur
multipliers. The lectures aimed at giving an overview of the subject with
emphasis on groups of Lie type over finite, real and $p$-adic fields.
| arxiv topic:math.GR math.NT math.RT |
arxiv_dataset-59691502.0224 | On the K-theory of linear groups
math.AT math.KT
We prove that for a finitely generated linear group G over a field of
positive characteristic the family of quotients by finite subgroups has finite
asymptotic dimension. We use this to show that the K-theoretic assembly map for
the family of finite subgroups is split injective for every finitely generated
linear group G over a commutative ring with unit under the assumption that G
admits a finite-dimensional model for the classifying space for the family of
finite subgroups. Furthermore, we prove that this is the case if and only if an
upper bound on the rank of the solvable subgroups of G exists.
| arxiv topic:math.AT math.KT |
arxiv_dataset-59701502.0234 | BSW process of the slowly evaporating charged black hole
gr-qc
In this paper, we study the BSW process of the slowly evaporating charged
black hole. It can be found that the BSW process will also arise near black
hole horizon when the evaporation of charged black hole is very slow. But now
the background black hole does not have to be an extremal black hole, and it
will be approximately an extremal black hole unless it is nearly a huge
stationary black hole.
| arxiv topic:gr-qc |
arxiv_dataset-59711502.0244 | Generalized switching signals for input-to-state stability of switched
systems
cs.SY math.OC
This article deals with input-to-state stability (ISS) of continuous-time
switched nonlinear systems. Given a family of systems with exogenous inputs
such that not all systems in the family are ISS, we characterize a new and
general class of switching signals under which the resulting switched system is
ISS. Our stabilizing switching signals allow the number of switches to grow
faster than an affine function of the length of a time interval, unlike in the
case of average dwell time switching. We also recast a subclass of average
dwell time switching signals in our setting and establish analogs of two
representative prior results.
| arxiv topic:cs.SY math.OC |
arxiv_dataset-59721502.0254 | Dissipation and decoherence by ideal quantum gas
cond-mat.stat-mech hep-th
The effective Lagrangian of a test particle, interacting with an ideal gas,
is calculated with in the closed time path formalism in the one-loop and the
leading order of the particle trajectory. The expansion in the time derivative
is available for slow enough motion and it uncovers diffusive effective forces
and decoherence for the coordinate and the momentum. A pure Newtonian friction
force and an anisotrop coordinate decoherence are found for zero temperature
ideal gas of fermions.
| arxiv topic:cond-mat.stat-mech hep-th |
arxiv_dataset-59731502.0264 | Inversion of the spherical means transform in corner-like domains by
reduction to the classical Radon transform
math.AP
We consider an inverse problem arising in thermo-/photo- acoustic tomography
that amounts to reconstructing a function $f$ from its circular or spherical
means with the centers lying on a given measurement surface. (Equivalently,
these means can be expressed through the solution $u(t,x)$ of the wave equation
with the initial pressure equal to $f$.) An explicit solution of this inverse
problem is obtained in 3D for the surface that is the boundary of an open
octet, and in 2D for the case when the centers of integration circles lie on
two rays starting at the origin and intersecting at the angle equal to $\pi/N$,
$N=2,3,4,...$. Our formulas reconstruct the Radon projections of a function
closely related to $f$, from the values of $u(t,x)$ on the measurement surface.
Then, function $f$ can be found by inverting the Radon transform.
| arxiv topic:math.AP |
arxiv_dataset-59741502.0274 | Gas flow in barred potentials
astro-ph.GA
We use a Cartesian grid to simulate the flow of gas in a barred Galactic
potential and investigate the effects of varying the sound speed in the gas and
the resolution of the grid. For all sound speeds and resolutions, streamlines
closely follow closed orbits at large and small radii. At intermediate radii
shocks arise and the streamlines shift between two families of closed orbits.
The point at which the shocks appear and the streamlines shift between orbit
families depends strongly on sound speed and resolution. For sufficiently large
values of these two parameters, the transfer happens at the cusped orbit as
hypothesised by Binney et al. over two decades ago. For sufficiently high
resolutions the flow downstream of the shocks becomes unsteady. If this
unsteadiness is physical, as appears to be the case, it provides a promising
explanation for the asymmetry in the observed distribution of CO.
| arxiv topic:astro-ph.GA |
arxiv_dataset-59751502.0284 | An Integrated Semantic Web Service Discovery and Composition Framework
cs.AI cs.SE
In this paper we present a theoretical analysis of graph-based service
composition in terms of its dependency with service discovery. Driven by this
analysis we define a composition framework by means of integration with
fine-grained I/O service discovery that enables the generation of a graph-based
composition which contains the set of services that are semantically relevant
for an input-output request. The proposed framework also includes an optimal
composition search algorithm to extract the best composition from the graph
minimising the length and the number of services, and different graph
optimisations to improve the scalability of the system. A practical
implementation used for the empirical analysis is also provided. This analysis
proves the scalability and flexibility of our proposal and provides insights on
how integrated composition systems can be designed in order to achieve good
performance in real scenarios for the Web.
| arxiv topic:cs.AI cs.SE |
arxiv_dataset-59761502.0294 | The Hilbert Space of Probability Mass Functions and Applications on
Probabilistic Inference
cs.IT math.IT math.PR
The Hilbert space of probability mass functions (pmf) is introduced in this
thesis. A factorization method for multivariate pmfs is proposed by using the
tools provided by the Hilbert space of pmfs. The resulting factorization is
special for two reasons. First, it reveals the algebraic relations between the
involved random variables. Second, it determines the conditional independence
relations between the random variables. Due to the first property of the
resulting factorization, it can be shown that channel decoders can be employed
in the solution of probabilistic inference problems other than decoding. This
approach might lead to new probabilistic inference algorithms and new hardware
options for the implementation of these algorithms. An example of new inference
algorithms inspired by the idea of using channel decoder for other inference
tasks is a multiple-input multiple-output (MIMO) detection algorithm which has
a complexity of the square-root of the optimum MIMO detection algorithm.
| arxiv topic:cs.IT math.IT math.PR |
arxiv_dataset-59771502.0304 | Amp\`ere-Class Pulsed Field Emission from Carbon-Nanotube Cathodes in a
Radiofrequency Resonator
physics.acc-ph
Pulsed field emission from cold carbon-nanotube cathodes placed in a
radiofrequency resonant cavity was observed. The cathodes were located on the
backplate of a conventional $1+\frac{1}{2}$-cell resonant cavity operating at
1.3-GHz and resulted in the production of bunch train with maximum average
current close to 0.7 Amp\`ere. The measured Fowler-Nordheim characteristic,
transverse emittance, and pulse duration are presented and, when possible,
compared to numerical simulations. The implications of our results to
high-average-current electron sources are briefly discussed.
| arxiv topic:physics.acc-ph |
arxiv_dataset-59781502.0314 | Synchronization Patterns in Geometrically Frustrated Turing Rings
nlin.PS
Coupled nonlinear oscillators can exhibit a wide variety of patterns. We
study the Brusselator as a prototypical autocatalytic reaction diffusion model.
Working in the limit of strong nonlinearity provides a clear timescale
separation that leads to a canard explosion in a single Brusselator. In this
highly nonlinear regime it is numerically found that rings of coupled
Brusselators do not follow the predictions from Turning analysis. We find that
the behavior can be explained using a piecewise linear approximation.
| arxiv topic:nlin.PS |
arxiv_dataset-59791502.0324 | Conditional Random Fields as Recurrent Neural Networks
cs.CV
Pixel-level labelling tasks, such as semantic segmentation, play a central
role in image understanding. Recent approaches have attempted to harness the
capabilities of deep learning techniques for image recognition to tackle
pixel-level labelling tasks. One central issue in this methodology is the
limited capacity of deep learning techniques to delineate visual objects. To
solve this problem, we introduce a new form of convolutional neural network
that combines the strengths of Convolutional Neural Networks (CNNs) and
Conditional Random Fields (CRFs)-based probabilistic graphical modelling. To
this end, we formulate mean-field approximate inference for the Conditional
Random Fields with Gaussian pairwise potentials as Recurrent Neural Networks.
This network, called CRF-RNN, is then plugged in as a part of a CNN to obtain a
deep network that has desirable properties of both CNNs and CRFs. Importantly,
our system fully integrates CRF modelling with CNNs, making it possible to
train the whole deep network end-to-end with the usual back-propagation
algorithm, avoiding offline post-processing methods for object delineation. We
apply the proposed method to the problem of semantic image segmentation,
obtaining top results on the challenging Pascal VOC 2012 segmentation
benchmark.
| arxiv topic:cs.CV |
arxiv_dataset-59801502.0334 | Scalable two- and four-qubit parity measurement with a threshold photon
counter
quant-ph
Parity measurement is a central tool to many quantum information processing
tasks. In this Letter, we propose a method to directly measure two- and
four-qubit parity with low overhead in hard- and software, while remaining
robust to experimental imperfections. Our scheme relies on dispersive
qubit-cavity coupling and photon counting that is sensitive only to intensity;
both ingredients are widely realized in many different quantum computing
modalities. For a leading technology in quantum computing, superconducting
integrated circuits, we analyze the measurement contrast and the back action of
the scheme and show that this measurement comes close enough to an ideal parity
measurement to be applicable to quantum error correction.
| arxiv topic:quant-ph |
arxiv_dataset-59811502.0344 | Emission of Cosmic Radio-waves, $X$- or $\gamma$-rays by Moving Unstable
Particles at Late Times
astro-ph.HE quant-ph
A new quantum effect connected with the late time behavior of decaying states
is described and its possible observational consequences are analyzed: It is
shown that charged unstable particles as well as neutral unstable particles
with non--zero magnetic moment which live sufficiently long may emit
electromagnetic radiation. This mechanism is due to the nonclassical behavior
of unstable particles at late times (at the post exponential time region).
Analyzing the transition times region between exponential and non-exponential
form of the survival amplitude it is found that the instantaneous energy of the
unstable particle can take very large values, much larger than the energy of
this state at times from the exponential time region. Based on the results
obtained for the model considered, it is shown that this new purely quantum
mechanical effect may be responsible for causing unstable particles produced by
astrophysical sources and moving with relativistic velocities to emit
electromagnetic--, $X$-- or $\gamma$--rays at some time intervals from the
transition time regions.
| arxiv topic:astro-ph.HE quant-ph |
arxiv_dataset-59821502.0354 | Evaluating Matrix Circuits
cs.CC math.GR
The circuit evaluation problem (also known as the compressed word problem)
for finitely generated linear groups is studied. The best upper bound for this
problem is $\mathsf{coRP}$, which is shown by a reduction to polynomial
identity testing. Conversely, the compressed word problem for the linear group
$\mathsf{SL}_3(\mathbb{Z})$ is equivalent to polynomial identity testing. In
the paper, it is shown that the compressed word problem for every finitely
generated nilpotent group is in $\mathsf{DET} \subseteq \mathsf{NC}^2$. Within
the larger class of polycyclic groups we find examples where the compressed
word problem is at least as hard as polynomial identity testing for skew
arithmetic circuits.
| arxiv topic:cs.CC math.GR |
arxiv_dataset-59831502.0364 | Symmetry improvement of 3PI effective actions for O(N) scalar field
theory
hep-th hep-ph
[Abridged] n-Particle Irreducible Effective Actions ($n$PIEA) are a powerful
tool for extracting non-perturbative and non-equilibrium physics from quantum
field theories. Unfortunately, practical truncations of $n$PIEA can
unphysically violate symmetries. Pilaftsis and Teresi (PT) addressed this by
introducing a "symmetry improvement" scheme in the context of the 2PIEA for an
O(2) scalar theory, ensuring that the Goldstone boson is massless in the broken
symmetry phase [A. Pilaftsis and D. Teresi, Nuc.Phys. B 874, 2 (2013), pp.
594--619]. We extend this by introducing a symmetry improved 3PIEA for O(N)
theories, for which the basic variables are the 1-, 2- and 3-point correlation
functions. This requires the imposition of a Ward identity involving the
3-point function. The method leads to an infinity of physically distinct
schemes, though an analogue of d'Alembert's principle is used to single out a
unique scheme. The standard equivalence hierarchy of $n$PIEA no longer holds
with symmetry improvement and we investigate the difference between the
symmetry improved 3PIEA and 2PIEA. We present renormalized equations of motion
and counter-terms for 2 and 3 loop truncations of the effective action, leaving
their numerical solution to future work. We solve the Hartree-Fock
approximation and find that our method achieves a middle ground between the
unimproved 2PIEA and PT methods. The phase transition predicted by our method
is weakly first order and the Goldstone theorem is satisfied. We also show
that, in contrast to PT, the symmetry improved 3PIEA at 2 loops does not
predict the correct Higgs decay rate, but does at 3 loops. These results
suggest that symmetry improvement should not be applied to $n$PIEA truncated to
$<n$ loops. We also show that symmetry improvement is compatible with the
Coleman-Mermin-Wagner theorem, a check on the consistency of the formalism.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-59841502.0374 | Uniform stability of linear evolution equations, with applications to
parallel transports
math.DG math.AP math.DS
I prove the bistability of linear evolution equations $x' = A(t)x$ in a
Banach space $E$, where the operator-valued function $A$ is of the form $A(t) =
f'(t)G(t,f(t))$ for a binary operator-valued function $G$ and a scalar function
$f$. The constant that bounds the solutions of the equation is computed
explicitly; it is independent of $f$, in a sense.
Two geometric applications of the stability result are presented. Firstly, I
show that the parallel transport along a curve $\gamma$ in a manifold, with
respect to some linear connection, is bounded in terms of the length of the
projection of $\gamma$ to a manifold of one dimension lower. Secondly, I prove
an extendability result for parallel sections in vector bundles, thereby
answering a question by Antonio J. Di Scala.
| arxiv topic:math.DG math.AP math.DS |
arxiv_dataset-59851502.0384 | Market Dynamics and Indirect Network Effects in Electric Vehicle
Diffusion
q-fin.EC
The diffusion of electric vehicles (EVs) is studied in a two-sided market
framework consisting of EVs on the one side and EV charging stations (EVCSs) on
the other. A sequential game is introduced as a model for the interactions
between an EVCS investor and EV consumers. A consumer chooses to purchase an EV
or a conventional gasoline alternative based on the upfront costs of purchase,
the future operating costs and the availability of charging stations. The
investor, on the other hand, maximizes his profit by deciding whether to build
charging facilities at a set of potential EVCS sites or to defer his
investments. The solution of the sequential game characterizes the EV-EVCS
market equilibrium. The market solution is compared with that of a social
planner who invests in EVCSs with the goal of maximizing the social welfare. It
is shown that the market solution underinvests EVCSs, leading to slower EV
diffusion. The effects of subsidies for EV purchase and EVCSs are also
considered.
| arxiv topic:q-fin.EC |
arxiv_dataset-59861502.0394 | Room Temperature Operation of a Buried Heterostructure Photonic Crystal
Quantum Cascade Laser
physics.optics
High power single mode quantum cascade lasers with a narrow far field are
important for several applications including surgery or military
countermeasure. Existing technologies suffer from drawbacks such as operation
temperature and scalability. In this paper we introduce a fabrication approach
that potentially solves simultaneously these remaining limitations. We
demonstrate and characterize deep etched, buried photonic crystal quantum
cascade lasers emitting around a wavelength of 8.5 {\mu}m. The active region
was dry etched before being regrown with semi-insulating Fe:InP. This
fabrication strategy results in a refractive index contrast of 10% allowing
good photonic mode control, and simultaneously provides good thermal extraction
during operation. Single mode emission with narrow far field pattern and peak
powers up to 0.88 W at 263 K were recorded from the facet of the photonic
crystal laser, and lasing operation was maintained up to room temperature. The
lasing modes emitted from square photonic crystal mesas with a side length of
550{\mu}m, were identified as slow Bloch photonic crystal modes by means of
three-dimensional photonic simulations and measurements.
| arxiv topic:physics.optics |
arxiv_dataset-59871502.0404 | Hypersurfaces that are not stably rational
math.AG
We show that a wide class of hypersurfaces in all dimensions are not stably
rational. Namely, for all d at least about 2n/3, a very general complex
hypersurface of degree d in P^{n+1} is not stably rational. The statement
generalizes Colliot-Thelene and Pirutka's theorem that very general quartic
3-folds are not stably rational. The result covers all the degrees in which
Kollar proved that a very general hypersurface is non-rational, and a bit more.
For example, very general quartic 4-folds are not stably rational, whereas it
was not even known whether these varieties are rational.
| arxiv topic:math.AG |
arxiv_dataset-59881502.0414 | Flavorspin
hep-ph
We propose that the flavor structure of the quark sector of the Standard
Model is determined by a vectorial SU(2) flavor symmetry, which we dub
Flavorspin, under which quarks transform as triplets. The fundamental Yukawa
couplings are real and CP violation is not directly linked to the breaking of
the flavor symmetry. A CP-conserving scenario is naturally defined with the
feature that the Yukawa spurions are completely determined in terms of the
masses and mixings. CP violation may be introduced with negligible impact on
low-energy observables other than generating a large CP violating phase in the
Standard Model mixing matrix. The scale of flavor-symmetry violation must be
large in order to prevent sizable Flavor Changing Neutral Currents, which can
be partially suppressed if Flavorspin is a residual symmetry of a larger flavor
group.
| arxiv topic:hep-ph |
arxiv_dataset-59891502.0424 | Scheduling of unit-length jobs with cubic incompatibility graphs on
three uniform machines
cs.DM
In the paper we consider the problem of scheduling $n$ identical jobs on 3
uniform machines with speeds $s_1, s_2,$ and $s_3$ to minimize the schedule
length. We assume that jobs are subjected to some kind of mutual exclusion
constraints, modeled by a cubic incompatibility graph. We show that if the
graph is 2-chromatic then the problem can be solved in $O(n^2)$ time. If the
graph is 3-chromatic, the problem becomes NP-hard even if $s_1>s_2=s_3$.
However, in this case there exists a $4/3$-approximation algorithm running in
$O(n^3)$ time. Moreover, this algorithm solves the problem almost surely to
optimality if $3s_1/4 \leq s_2 = s_3$.
| arxiv topic:cs.DM |
arxiv_dataset-59901502.0434 | On teaching sets of k-threshold functions
math.CO
Let $f$ be a $\{0,1\}$-valued function over an integer $d$-dimensional cube
$\{0,1,\dots,n-1\}^d$, for $n \geq 2$ and $d \geq 1$. The function $f$ is
called threshold if there exists a hyperplane which separates $0$-valued points
from $1$-valued points. Let $C$ be a class of functions and $f \in C$. A point
$x$ is essential for the function $f$ with respect to $C$ if there exists a
function $g \in C$ such that $x$ is a unique point on which $f$ differs from
$g$. A set of points $X$ is called teaching for the function $f$ with respect
to $C$ if no function in $C \setminus \{f\}$ agrees with $f$ on $X$. It is
known that any threshold function has a unique minimal teaching set, which
coincides with the set of its essential points. In this paper we study teaching
sets of $k$-threshold functions, i.e. functions that can be represented as a
conjunction of $k$ threshold functions. We reveal a connection between
essential points of $k$ threshold functions and essential points of the
corresponding $k$-threshold function. We note that, in general, a $k$-threshold
function is not specified by its essential points and can have more than one
minimal teaching set. We show that for $d=2$ the number of minimal teaching
sets for a 2-threshold function can grow as $\Omega(n^2)$. We also consider the
class of polytopes with vertices in the $d$-dimensional cube. Each polytope
from this class can be defined by a $k$-threshold function for some $k$. In
terms of $k$-threshold functions we prove that a polytope with vertices in the
$d$-dimensional cube has a unique minimal teaching set which is equal to the
set of its essential points. For $d=2$ we describe structure of the minimal
teaching set of a polytope and show that cardinality of this set is either
$\Theta(n^2)$ or $O(n)$ and depends on the perimeter and the minimum angle of
the polytope.
| arxiv topic:math.CO |
arxiv_dataset-59911502.0444 | Ergodicity and fluctuations of a fluid particle driven by diffusions
with jumps
math.PR
In this paper, we study the long-time behavior of a fluid particle immersed
in a turbulent fluid driven by a diffusion with jumps, that is, a Feller
process associated with a non-local operator. We derive the law of large
numbers and central limit theorem for the evolution process of the tracked
fluid particle in the cases when the driving process: (i) has periodic
coefficients, (ii) is ergodic or (iii) is a class of L\'evy processes. The
presented results generalize the classical and well-known results for fluid
flows driven by elliptic diffusion processes.
| arxiv topic:math.PR |
arxiv_dataset-59921502.0454 | Disjoint sparsity for signal separation and applications to hybrid
inverse problems in medical imaging
math.AP math.NA
The main focus of this work is the reconstruction of the signals $f$ and
$g_{i}$, $i=1,...,N$, from the knowledge of their sums $h_{i}=f+g_{i}$, under
the assumption that $f$ and the $g_{i}$'s can be sparsely represented with
respect to two different dictionaries $A_{f}$ and $A_{g}$. This generalizes the
well-known "morphological component analysis" to a multi-measurement setting.
The main result of the paper states that $f$ and the $g_{i}$'s can be uniquely
and stably reconstructed by finding sparse representations of $h_{i}$ for every
$i$ with respect to the concatenated dictionary $[A_{f},A_{g}]$, provided that
enough incoherent measurements $g_{i}$ are available. The incoherence is
measured in terms of their mutual disjoint sparsity.
This method finds applications in the reconstruction procedures of several
hybrid imaging inverse problems, where internal data are measured. These
measurements usually consist of the main unknown multiplied by other unknown
quantities, and so the disjoint sparsity approach can be directly applied. As
an example, we show how to apply the method to the reconstruction in
quantitative photoacoustic tomography, also in the case when the Gr\"uneisen
parameter, the optical absorption and the diffusion coefficient are all
unknown.
| arxiv topic:math.AP math.NA |
arxiv_dataset-59931502.0464 | The Lorentzian proper vertex amplitude: Classical analysis and quantum
derivation
gr-qc
Spin foam models, an approach to defining the dynamics of loop quantum
gravity, make use of the Plebanski formulation of gravity, in which gravity is
recovered from a topological field theory via certain constraints called
simplicity constraints. However, the simplicity constraints in their usual form
select more than just one gravitational sector as well as a degenerate sector.
This was shown, in previous work, to be the reason for the "extra" terms
appearing in the semiclassical limit of the Euclidean EPRL amplitude. In this
previous work, a way to eliminate the extra sectors, and hence terms, was
developed, leading to the what was called the Euclidean proper vertex
amplitude. In the present work, these results are extended to the Lorentzian
signature, establishing what is called the Lorentzian proper vertex amplitude.
This extension is non-trivial and involves a number of new elements since, for
Lorentzian bivectors, the split into self-dual and anti-self-dual parts, on
which the Euclidean derivation was based, is no longer available. In fact, the
classical parts of the present derivation provide not only an extension to the
Lorentzian case, but also, with minor modifications, provide a new, more four
dimensionally covariant derivation for the Euclidean case. The new elements in
the quantum part of the derivation are due to the different structure of
unitary representations of the Lorentz group.
| arxiv topic:gr-qc |
arxiv_dataset-59941502.0474 | Conditional Heteroskedasticity of Return Range Processes
stat.ME
Price range contains important information about the asset volatility, and
has long been considered an important indicator for it. In this paper, we
propose to jointly model the [low, high] price range as a random interval and
introduce an interval-valued GARCH (Int-GARCH) model for the corresponding
[low, high] return range process. Model properties are presented under the
general framework of random sets, and the parameters are estimated by a
metric-based conditional least squares (CLS) method. Our empirical analysis of
the daily return range data of Dow Jones component stocks yields very
interesting results.
| arxiv topic:stat.ME |
arxiv_dataset-59951502.0484 | Measurement of the cosmic ray all-particle and light-component energy
spectra with the ARGO-YBJ experiment
astro-ph.HE
ARGO-YBJ preliminary results of the measurements of the all-particle and
light-component (i.e. protons and helium) cosmic ray energy spectra between
approximately 5 TeV and 5 PeV are reported and discussed. The resulting
all-particle spectrum (measured in the energy range 100TeV - 3PeV) is in good
agreement with both theoretical parametrizations and previous measurements. The
light-component (i.e. p + He) has been measured with high resolution up to
about 5 PeV. The preliminary result is in agreement with direct measurements
and then show a clear indication of a bending below 1PeV. Improvements of event
selection/reconstruction with the full statistics and a complete analysis of
systematic uncertainties is currently under way.
| arxiv topic:astro-ph.HE |
arxiv_dataset-59961502.0494 | Stochastic Averaging in Discrete Time and Its Applications to Extremum
Seeking
math.OC
We investigate stochastic averaging theory for locally Lipschitz
discrete-time nonlinear systems with stochastic perturbation and its
applications to convergence analysis of discrete-time stochastic extremum
seeking algorithms. Firstly, by defining two average systems (one is continuous
time, the other is discrete time), we develop discrete-time stochastic
averaging theorem for locally Lipschitz nonlinear systems with stochastic
perturbation. Our results only need some simple and applicable conditions,
which are easy to verify, and remove a significant restriction present in
existing results: global Lipschitzness of the nonlinear vector field. Secondly,
we provide a discrete-time stochastic extremum seeking algorithm for a static
map, in which measurement noise is considered and an ergodic discrete-time
stochastic process is used as the excitation signal. Finally, for discrete-time
nonlinear dynamical systems, in which the output equilibrium map has an
extremum, we present a discrete-time stochastic extremum seeking scheme and,
with a singular perturbation reduction, we prove the stability of the reduced
system. Compared with classical stochastic approximation methods, while the
convergence that we prove is in a weaker sense, the conditions of the algorithm
are easy to verify and no requirements (e.g., boundedness) are imposed on the
algorithm itself.
| arxiv topic:math.OC |
arxiv_dataset-59971502.0504 | Design of a Framework to Facilitate Decisions Using Information Fusion
cs.AI
Information fusion is an advanced research area which can assist decision
makers in enhancing their decisions. This paper aims at designing a new
multi-layer framework that can support the process of performing decisions from
the obtained beliefs using information fusion. Since it is not an easy task to
cross the gap between computed beliefs of certain hypothesis and decisions, the
proposed framework consists of the following layers in order to provide a
suitable architecture (ordered bottom up): 1. A layer for combination of basic
belief assignments using an information fusion approach. Such approach exploits
Dezert-Smarandache Theory, DSmT, and proportional conflict redistribution to
provide more realistic final beliefs. 2. A layer for computation of pignistic
probability of the underlying propositions from the corresponding final
beliefs. 3. A layer for performing probabilistic reasoning using a Bayesian
network that can obtain the probable reason of a proposition from its pignistic
probability. 4. Ranking the system decisions is ultimately used to support
decision making. A case study has been accomplished at various operational
conditions in order to prove the concept, in addition it pointed out that: 1.
The use of DSmT for information fusion yields not only more realistic beliefs
but also reliable pignistic probabilities for the underlying propositions. 2.
Exploiting the pignistic probability for the integration of the information
fusion with the Bayesian network provides probabilistic inference and enable
decision making on the basis of both belief based probabilities for the
underlying propositions and Bayesian based probabilities for the corresponding
reasons. A comparative study of the proposed framework with respect to other
information fusion systems confirms its superiority to support decision making.
| arxiv topic:cs.AI |
arxiv_dataset-59981502.0514 | Measuring the equation of state of the high-z intergalactic medium using
curvature statistics
astro-ph.CO
Using hydrodynamical simulations, we explore the use of the mean and
percentiles of the curvature distribution function to recover the equation of
state of the high-$z$ ($2 < z < 4$) intergalactic medium (IGM). We find that
the mean and percentiles of the absolute curvature distribution exhibit tight
correlation with the temperatures measured at respective characteristic
overdensities $\bar{\Delta}_i$'s at each redshift. Hence, they provide
complementary probes of the same underlying temperature-density distribution,
and can in principle be used to simultaneously recover both parameters $T_0$
and $\gamma$ of the IGM effective equation of state. We quantify the associated
errors in the recovered parameters $T_0$ and $\gamma$ from the intrinsic
scatter in the characteristic overdensities and the uncertainties in the
curvature measurement.
| arxiv topic:astro-ph.CO |
arxiv_dataset-59991502.0524 | Non-commutative resolutions of quotient singularities
math.AG math.RT
In this paper we generalize standard results about non-commutative
resolutions of quotient singularities for finite groups to arbitrary reductive
groups. We show in particular that quotient singularities for reductive groups
always have non-commutative resolutions in an appropriate sense. Moreover we
exhibit a large class of such singularities which have (twisted)
non-commutative crepant resolutions.
We discuss a number of examples, both new and old, that can be treated using
our methods. Notably we prove that twisted non-commutative crepant resolutions
exist in previously unknown cases for determinantal varieties of symmetric and
skew-symmetric matrices.
In contrast to almost all prior results in this area our techniques are
algebraic and do not depend on knowing a commutative resolution of the
singularity.
| arxiv topic:math.AG math.RT |
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