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arxiv_dataset-40001301.341 | Fractures in complex fluids: the case of transient networks
cond-mat.soft
We present a comprehensive review of the current state of fracture phenomena
in transient networks, a wide class of viscoelastic fluids. We will first
define what is a fracture in a complex fluid, and recall the main structural
and rheological properties of transient networks. Secondly, we review
experimental reports on fractures of transient networks in several
configurations: shear-induced fractures, fractures in Hele-Shaw cells and
fracture in extensional geometries (filament stretching rheometry and pendant
drop experiments), including fracture propagation. The tentative extension of
the concepts of brittleness and ductility to the fracture mechanisms in
transient networks is also discussed. Finally, the different and apparently
contradictory theoretical approaches developed to interpret fracture nucleation
will be addressed and confronted to experimental results. Rationalized criteria
to discriminate the relevance of these different models will be proposed.
| arxiv topic:cond-mat.soft |
arxiv_dataset-40011301.351 | Polynomials with no zeros on a face of the bidisk
math.CV math.FA
We present a Hilbert space geometric approach to the problem of
characterizing the positive bivariate trigonometric polynomials that can be
represented as the square of a two variable polynomial possessing a certain
stability requirement, namely no zeros on a face of the bidisk. Two different
characterizations are given using a Hilbert space structure naturally
associated to the trigonometric polynomial; one is in terms of a certain
orthogonal decomposition the Hilbert space must possess called the "split-shift
orthogonality condition" and another is an operator theoretic or matrix
condition closely related to an earlier characterization due to the first two
authors. This approach allows several refinements of the characterization and
it also allows us to prove a sums of squares decomposition which at once
generalizes the Cole-Wermer sums of squares result for two variable stable
polynomials as well as a sums of squares result related to the Schur-Cohn
method for counting the roots of a univariate polynomial in the unit disk.
| arxiv topic:math.CV math.FA |
arxiv_dataset-40021301.361 | Effects of Magnetic Field and FUV Radiation on the Structures of
Bright-rimmed Clouds
astro-ph.SR
The bright-rimmed cloud SFO 22 was observed with the 45 m telescope of
Nobeyama Radio Observatory in the ^{12}CO (J = 1-0), ^{13}CO (J = 1-0), and
C^{18}O (J = 1-0) lines, where well-developed head-tail structure and small
line widths were found. Such features were predicted by radiation-driven
implosion models, suggesting that SFO 22 may be in a quasi-stationary
equilibrium state. We compare the observed properties with those from numerical
models of a photo-evaporating cloud, which include effects of magnetic pressure
and heating due to strong far-ultraviolet (FUV) radiation from an exciting
star. The magnetic pressure may play a more important role in the density
structures of bright-rimmed clouds, than the thermal pressure that is enhanced
by the FUV radiation. The FUV radiation can heat the cloud surface to near 30
K, however, its effect is not enough to reproduce the observed density
structure of SFO 22. An initial magnetic field of 5 \mu G in our numerical
models produces the best agreement with the observations, and its direction can
affect the structures of bright-rimmed clouds.
| arxiv topic:astro-ph.SR |
arxiv_dataset-40031301.371 | Creation of Ghost Illusions Using Metamaterials in Wave Dynamics
physics.optics
The creation of wave-dynamic illusion functionality is of great interests to
various scientific communities, which can potentially transform an actual
perception into the pre-controlled perception, thus empowering unprecedented
applications in the advanced-material science, camouflage, cloaking, optical
and/or microwave cognition, and defense security, etc. By using the space
transformation theory and engineering capability of metamaterials, we propose
and realize a functional ghost illusion device, which is capable of creating
wave-dynamic virtual ghost images off the original object's position under the
illumination of electromagnetic waves. The scattering signature of the object
is thus ghosted and perceived as multiple ghost targets with different
geometries and compositions. The ghost-illusion material, being inhomogeneous
and anisotropic, was realized by thousands of varying unit cells working at
non-resonance. The experimental demonstration of the ghost illusion validates
our theory of scattering metamorphosis and opens a novel avenue to the
wave-dynamic illusion, cognitive deception, manipulate strange light or matter
behaviors, and design novel optical and microwave devices.
| arxiv topic:physics.optics |
arxiv_dataset-40041301.381 | Orthogonal Polynomials on the Unit Circle with quasiperiodic Verblunsky
Coefficients have generic purely singular continuous spectrum
math.SP math-ph math.DS math.MP
As an application of the Gordon lemma for orthogonal polynomials on the unit
circle, we prove that for a generic set of quasiperiodic Verblunsky
coefficients the corresponding two-sided CMV operator has purely singular
continuous spectrum. We use a similar argument to that of the
Boshernitzan-Damanik result that establishes the corresponding theorem for the
discrete Schr\"odinger operator.
| arxiv topic:math.SP math-ph math.DS math.MP |
arxiv_dataset-40051301.391 | Hybrid methods in planetesimal dynamics: Formation of protoplanetary
systems and the mill condition
astro-ph.EP astro-ph.SR
The formation and evolution of protoplanetary discs remains a challenge from
both a theoretical and numerical standpoint. In this work we first perform a
series of tests of our new hybrid algorithm presented in Glaschke, Amaro-Seoane
and Spurzem 2011 (henceforth Paper I) that combines the advantages of high
accuracy of direct-summation N-body methods with a statistical description for
the planetesimal disc based on Fokker-Planck techniques. We then address the
formation of planets, with a focus on the formation of protoplanets out of
planetesimals. We find that the evolution of the system is driven by encounters
as well as direct collisions and requires a careful modelling of the evolution
of the velocity dispersion and the size distribution over a large range of
sizes. The simulations show no termination of the protoplanetary accretion due
to gap formation, since the distribution of the planetesimals is only subjected
to small fluctuations. We also show that these features are weakly correlated
with the positions of the protoplanets. The exploration of different impact
strengths indicates that fragmentation mainly controls the overall mass loss,
which is less pronounced during the early runaway growth. We prove that the
fragmentation in combination with the effective removal of collisional
fragments by gas drag sets an universal upper limit of the protoplanetary mass
as a function of the distance to the host star, which we refer to as the mill
condition.
| arxiv topic:astro-ph.EP astro-ph.SR |
arxiv_dataset-40061301.401 | Approximating Bin Packing within O(log OPT * log log OPT) bins
cs.DS math.CO
For bin packing, the input consists of n items with sizes s_1,...,s_n in
[0,1] which have to be assigned to a minimum number of bins of size 1. The
seminal Karmarkar-Karp algorithm from '82 produces a solution with at most OPT
+ O(log^2 OPT) bins.
We provide the first improvement in now 3 decades and show that one can find
a solution of cost OPT + O(log OPT * log log OPT) in polynomial time. This is
achieved by rounding a fractional solution to the Gilmore-Gomory LP relaxation
using the Entropy Method from discrepancy theory. The result is constructive
via algorithms of Bansal and Lovett-Meka.
| arxiv topic:cs.DS math.CO |
arxiv_dataset-40071301.411 | Note on the hydrodynamic description of thin nematic films: strong
anchoring model
physics.flu-dyn cond-mat.soft
We discuss the long-wave hydrodynamic model for a thin film of nematic liquid
crystal in the limit of strong anchoring at the free surface and at the
substrate. We rigorously clarify how the elastic energy enters the evolution
equation for the film thickness in order to provide a solid basis for further
investigation: several conflicting models exist in the literature that predict
qualitatively different behaviour. We consolidate the various approaches and
show that the long-wave model derived through an asymptotic expansion of the
full nemato-hydrodynamic equations with consistent boundary conditions agrees
with the model one obtains by employing a thermodynamically motivated gradient
dynamics formulation based on an underlying free energy functional. As a
result, we find that in the case of strong anchoring the elastic distortion
energy is always stabilising. To support the discussion in the main part of the
paper, an appendix gives the full derivation of the evolution equation for the
film thickness via asymptotic expansion.
| arxiv topic:physics.flu-dyn cond-mat.soft |
arxiv_dataset-40081301.421 | Bivariant Algebraic Cobordism
math.AG
We associate a bivariant theory to any suitable oriented Borel-Moore homology
theory on the category of algebraic schemes or the category of algebraic
G-schemes. Applying this to the theory of algebraic cobordism yields
operational cobordism rings and operational G-equivariant cobordism rings
associated to all schemes in these categories. In the case of toric varieties,
the operational T-equivariant cobordism ring may be described as the ring of
piecewise graded power series on the fan with coefficients in the Lazard ring.
| arxiv topic:math.AG |
arxiv_dataset-40091301.431 | Fluctuation corrections on thermodynamic functions: Finite size effect
quant-ph
The explicit thermodynamic functions, in particular, the specific heat of a
spin system interacting with a spin bath which exerts finite dissipation on the
system are determined. We show that the specific heat is a sum of the products
of a thermal equilibration factor that carries the temperature dependence and a
dynamical correction factor, characteristic of the dissipative energy flow
under steady state from the system. The variation of specific heat with
temperature is accompanied by an abrupt transition that depends on these
dynamical factors characteristic of the finite system size.
| arxiv topic:quant-ph |
arxiv_dataset-40101301.441 | First observation of $^{13}$Li ground state
nucl-ex
The ground state of neutron-rich unbound $^{13}$Li was observed for the first
time in a one-proton removal reaction from $^{14}$Be at a beam energy of 53.6
MeV/u. The $^{13}$Li ground state was reconstructed from $^{11}$Li and two
neutrons giving a resonance energy of 120$^{+60}_{-80}$ keV. All events
involving single and double neutron interactions in the Modular Neutron Array
(MoNA) were analyzed, simulated, and fitted self-consistently. The three-body
($^{11}$Li+$n+n$) correlations within Jacobi coordinates showed strong
dineutron characteristics. The decay energy spectrum of the intermediate
$^{12}$Li system ($^{11}$Li+$n$) was described with an s-wave scattering length
of greater than -4 fm, which is a smaller absolute value than reported in a
previous measurement.
| arxiv topic:nucl-ex |
arxiv_dataset-40111301.451 | Geometric nullstellensatz and symbolic powers on arbitrary varieties
math.AG math.AC
In recent years, a multiplier ideal defined on arbitrary varieties, so called
Mather multiplier ideal, has been developed independently by Ein-Ishii-Mustata,
and de Fernex-Docampo. With this new tool, we have a chance of extending some
classical results proved in nonsingular case to arbitrary varieties to
establish their general forms. In this paper, we first extend a result of
geometric nullstellensatz due to Ein-Lazarsfeld in nonsingular case to any
projective varieties. Then we prove a result on comparison of symbolic powers
with ordinary powers on any varieties, which extends results of
Ein-Lazarsfeld-Smith and Hochster-Huneke.
| arxiv topic:math.AG math.AC |
arxiv_dataset-40121301.461 | On the Weyl-Titchmarsh and Liv\v{s}ic functions
math.SP
We establish a mutual relationship between main analytic objects for the
dissipative extension theory of a symmetric operator $\dot A$ with deficiency
indices $(1,1)$. In particular, we introduce the Weyl-Titchmarsh function $\cM$
of a maximal dissipative extension $\hat A$ of the symmetric operator $\dot A$.
Given a reference self-adjoint extension $A$ of $\dot A$, we introduce a von
Neumann parameter $\kappa$, $|\kappa|<1$, characterizing the domain of the
dissipative extension $\hat A$ against $\Dom (A)$ and show that the pair
$(\kappa, \cM)$ is a complete unitary invariant of the triple $(\dot A, A, \hat
A)$, unless $\kappa=0$. As a by-product of our considerations we obtain a
relevant functional model for a dissipative operator and get an analog of the
formula of Krein for its resolvent.
| arxiv topic:math.SP |
arxiv_dataset-40131301.471 | Character clusters for Lie algebra modules over a field of non-zero
characteristic
math.RA
For a Lie algebra L over an algebraically closed field of non-zero
characteristic, every finite-dimensional L-module can be decomposed into a
direct sum of submodules such that all composition factors of a summand have
the same character. Using the concept of a character cluster, this result is
generalised to fields which are not algebraically closed. Clusters are used to
generalise the construction of induced modules.
| arxiv topic:math.RA |
arxiv_dataset-40141301.481 | A note on local gradient estimate on Alexandrov spaces
math.MG
In this note, we prove Cheng-Yau type local gradient estimate for harmonic
functions on Alexandrov spaces with Ricci curvature bounded below. We adopt a
refined version of Moser's iteration which is based on Zhang-Zhu's Bochner type
formula. Our result improves the previous one of Zhang-Zhu in the case of
negative Ricci lower bound.
| arxiv topic:math.MG |
arxiv_dataset-40151301.491 | Computational Aspects of the Calculus of Structure
cs.LO cs.AI
Logic is the science of correct inferences and a logical system is a tool to
prove assertions in a certain logic in a correct way. There are many logical
systems, and many ways of formalizing them, e.g., using natural deduction or
sequent calculus. Calculus of structures (CoS) is a new formalism proposed by
Alessio Guglielmi in 2004 that generalizes sequent calculus in the sense that
inference rules can be applied at any depth inside a formula, rather than only
to the main connective. With this feature, proofs in CoS are shorter than in
any other formalism supporting analytical proofs. Although it is great to have
the freedom and expressiveness of CoS, under the point of view of proof search
more freedom means a larger search space. And that should be restricted when
looking for complete automation of deductive systems. Some efforts were made to
reduce this non-determinism, but they are all basically operational approaches,
and no solid theoretical result regarding the computational behaviour of CoS
has been achieved so far. The main focus of this thesis is to discuss ways to
propose a proof search strategy for CoS suitable to implementation. This
strategy should be theoretical instead of purely operational. We introduce the
concept of incoherence number of substructures inside structures and we use
this concept to achieve our main result: there is an algorithm that, according
to our conjecture, corresponds to a proof search strategy to every provable
structure in the subsystem of FBV (the multiplicative linear logic MLL plus the
rule mix) containing only pairwise distinct atoms. Our algorithm is implemented
and we believe our strategy is a good starting point to exploit the
computational aspects of CoS in more general systems, like BV itself.
| arxiv topic:cs.LO cs.AI |
arxiv_dataset-40161301.501 | Mass segregation in the diffuse outer-halo globular cluster Palomar 14
astro-ph.GA
We present an analysis of the radial dependence of the stellar mass function
in the diffuse outer-halo globular cluster Palomar 14. Using archival HST/WFPC2
data of the cluster's central 39 pc (corresponding to ~0.85*r_h) we find that
the mass function in the mass range of 0.55 to 0.85 solar masses is well
approximated by a power-law at all radii. The mass function steepens with
increasing radius, from a shallow power-law slope of 0.66+/-0.32 in the
cluster's centre to a slope of 1.61+/-0.33 beyond the core radius, showing that
the cluster is mass-segregated. This is seemingly in conflict with its long
present-day half-mass relaxation time of ~20 Gyr, and with the recent finding
by Beccari et al. (2011), who interpret the cluster's non-concentrated
population of blue straggler stars as evidence that dynamical segregation has
not affected the cluster yet. We discuss this apparent conflict and argue that
the cluster must have either formed with primordial mass segregation, or that
its relaxation time scale must have been much smaller in the past, i.e. that
the cluster must have undergone a significant expansion.
| arxiv topic:astro-ph.GA |
arxiv_dataset-40171301.511 | On the Concept of Law in Physics
physics.hist-ph gr-qc
I discuss the main features of the concept of law in physics. Fundamental
laws from Newtonian mechanics to general relativity are reviewed. I end with an
outlook on the new form of laws in the emerging theory of quantum gravity.
| arxiv topic:physics.hist-ph gr-qc |
arxiv_dataset-40181301.521 | Studying the Interplay of Strong and Electromagnetic Forces in Heavy Ion
Collisions with NICA
nucl-th hep-ex hep-ph nucl-ex
In the following we stress the advantages of the NICA research programme in
the context of studying the spectator-induced electromagnetic phenomena present
in proton-nucleus and heavy ion collisions. We point at the specific interest
of using these phenomena as a new, independent source of information on the
space-time evolution of the reaction and of the non-perturbative process of
particle production. We propose an extended series of measurements of
well-defined observables to be performed in different types of nuclear
reactions and in the whole range of collision energies available to NICA. We
expect these measurements to bring very valuable new insight into the mechanism
of non-perturbative strong interactions, complementary to the studies made at
the SPS at CERN, RHIC at BNL, and the LHC.
| arxiv topic:nucl-th hep-ex hep-ph nucl-ex |
arxiv_dataset-40191301.531 | Dual quantum information splitting with degenerate graph states
quant-ph
We propose a protocol for secret sharing, called dual quantum information
splitting (DQIS), that reverses the roles of state and channel in standard
quantum information splitting. In this method, a secret is shared via
teleportation of a fiducial input state over an entangled state that encodes
the secret in a graph state basis. By performing a test of violation of a Bell
inequality on the encoded state, the legitimate parties determine if the
violation is sufficiently high to permit distilling secret bits. Thus, the code
space must be maximally and exclusively nonlocal. To this end, we propose two
ways to obtain code words that are degenerate with respect to a Bell operator.
The security of DQIS comes from monogamy of nonlocal correlations, which we
illustrate by means of a simple single-qubit attack model. The nonlocal basis
of security of our protocol makes it suitable for security in general
monogamous theories and in the more stringent, device-independent cryptographic
scenario.
| arxiv topic:quant-ph |
arxiv_dataset-40201301.541 | Cancellativization of dimer models
math.AG
We show that any dimer model can be made cancellative without changing the
characteristic polygon.
| arxiv topic:math.AG |
arxiv_dataset-40211301.551 | Statistical testing of shared genetic control for potentially related
traits
q-bio.GN stat.AP
Integration of data from genome-wide single nucleotide polymorphism (SNP)
association studies of different traits should allow researchers to disentangle
the genetics of potentially related traits within individually associated
regions. Formal statistical colocalisation testing of individual regions, which
requires selection of a set of SNPs summarizing the association in a region. We
show that the SNP selection method greatly affects type 1 error rates, with
published studies having used methods expected to result in substantially
inflated type 1 error rates. We show that either avoiding variable selection
and instead testing the most informative principal components or integrating
over variable selection using Bayesian model averaging can lead to correct
control of type 1 error rates. Application to data from Graves' disease and
Hashimoto's thyroiditis reveals a common genetic signature across seven regions
shared between the diseases, and indicates that in five of six regions
associated with Graves' disease and not Hashimoto's thyroiditis, this more
likely reflects genuine absence of association with the latter rather than lack
of power. Our examination, by simulation, of the performance of colocalisation
tests and associated software will foster more widespread adoption of formal
colocalisation testing. Given the increasing availability of large expression
and genetic association data sets from disease-relevant tissue and purified
cell populations, coupled with identification of regulatory sequences by
projects such as ENCODE, colocalisation analysis has the potential to reveal
both shared genetic signatures of related traits and causal disease genes and
tissues.
| arxiv topic:q-bio.GN stat.AP |
arxiv_dataset-40221301.561 | Routing quantum information in spin chains
quant-ph
Two different models for performing efficiently routing of a quantum state
are presented. Both cases involve an XX spin chain working as data bus and
additional spins that play the role of sender and receivers, one of which is
selected to be the target of the quantum state transmission protocol via a
coherent quantum coupling mechanism making use of local/global magnetic fields.
Quantum routing is achieved, in the first of the models considered, by weakly
coupling the sender and the receiver to the data bus. In the second model,
strong magnetic fields acting on additional spins located between the
sender/receiver and the data bus allow us to perform high fidelity routing.
| arxiv topic:quant-ph |
arxiv_dataset-40231301.571 | Characteristics Analysis and State Transfer for non-Markovian Open
Quantum Systems
quant-ph
The weak-coupled two-level open quantum system described by non-Markovian
Time-convolution-less master equation is investigated in this paper. The
cut-off frequency, coupling constant and transition frequency, which impact on
the system's decay rate, coherence factor and purity, are investigated. The
appropriate parameters used in system simulation experiments are determined by
comparing analysis results of different values of parameters for the effects of
system performance. The control laws used to transfer the system states are
designed on the basis of the Lyapunov stability theorem. Numerical simulation
experiments are implemented under the MATLAB environment. The features of the
free evolution trajectory of the non-Markovian systems and the states transfer
from a pure state to a desired pure state under the action of the proposed
control laws are studied, respectively. By comparing the experimental results,
the effectiveness of the proposed quantum Lyapunov control method applied to
the state transfer in non-Markovian open quantum systems is verified.
Meanwhile, the influences of different control parameters and cut-off
frequencies on the system performance are analyzed.
| arxiv topic:quant-ph |
arxiv_dataset-40241301.581 | Studies of highly-boosted top quarks near the TeV scale using jet masses
at the LHC
hep-ph
Studies of highly-boosted top quarks produced inclusively in pp collisions at
14 TeV are discussed. The hadronic decays of boosted top quarks was studied in
a data-driven approach by analysing shapes of jet-mass distributions. Using
Monte Carlo models after a fast detector simulation, it is shown that inclusive
production of boosted top quarks can be observed if it has a cross section at
least twice larger than the prediction from the approximate
next-to-next-to-leading-order (aNNLO) calculation for the ttbar process. The
ttbar process with the nominal aNNLO strength can be measured using the masses
of jets after a b-tagging.
| arxiv topic:hep-ph |
arxiv_dataset-40251301.591 | The Zariski-Lipman conjecture for log canonical spaces
math.AG math.AC
In this paper we prove the Zariski-Lipman conjecture for log canonical
spaces.
| arxiv topic:math.AG math.AC |
arxiv_dataset-40261301.601 | Analysis of the triplet production by the circularly polarized photon at
high energies
hep-ph
The possibility in principle of the determining high energy photon circular
polarization by the measurement of the created electron polarization in the
process of triplet photoproduction $\gamma +e^-\rightarrow e^+e^- +e^-$ is
investigated. The respective event number which depend on polarization states
of photon and created electron does not decrease with the growth of the photon
energy, and this circumstance can ensure the high efficiency in such kind of
experiments. We study different double and single distributions of the created
electron (or positron), which allow to probe the photon circular polarization
and to measure its magnitude (the Stock's parameter $\xi_2$), using the
technique of the Sudakov's variables. Some experimental setups with different
rules for event selection are studied and corresponding numerical estimations
are presented.
| arxiv topic:hep-ph |
arxiv_dataset-40271301.611 | N-body simulations of oligarchic growth of Mars: Implications for Hf-W
chronology
astro-ph.EP
Dauphas and Pourmand (2011) [Nature 473, 489--492] estimated the accretion
timescale of Mars to be 1.8 $^{+0.9}_{-1.0}$ Myr from the W isotopes of martian
meteorites. This timescale was derived assuming perfect metal-silicate
equilibration between the impactor and the target's mantle. However, in the
case of a small impactor most likely only a fraction of the target's mantle is
involved in the equilibration, while only a small part of the impactor's core
equilibrates in the case of a giant impact. We examined the effects of
imperfect equilibration using results of high-resolution $N$-body simulations
for the oligarchic growth stage. These effects were found to be small as long
as a planetary embryo has a deep liquid magma ocean during its accretion. The
effect due to partial involvement of the target's mantle in equilibration is
small due to the low metal-silicate partition coefficient for W suggested from
the low Hf/W ratio of the martian mantle. The effect due to partial involvement
of the impactor's core is also small because a large fraction of the embryo
mass is delivered from small planetesimals, which are likely to fully
equilibrate in the deep magma ocean on the embryo. The accretion timescale of
Mars estimated by the Hf-W chronology is shorter than that expected for the
minimum mass solar nebula model as long as more than 10% of each impactor's
core re-equilibrates with the martian mantle and the final stages of accretion
are prolonged. This probably indicates that accretion of Mars proceeded rapidly
due to solid and gas surface densities significantly larger than those for the
minimum mass solar nebula or due to accretion of small fragments or pebbles.
| arxiv topic:astro-ph.EP |
arxiv_dataset-40281301.621 | Embedding loop quantum cosmology without piecewise linearity
gr-qc
An important goal is to understand better the relation between full loop
quantum gravity (LQG) and the simplified, reduced theory known as loop quantum
cosmology (LQC), {\em directly at the quantum level}. Such a firmer
understanding would increase confidence in the reduced theory as a tool for
formulating predictions of the full theory, as well as permitting lessons from
the reduced theory to guide further development in the full theory. The present
paper constructs an embedding of the usual state space of LQC into that of
standard LQG, that is, LQG based on \textit{piecewise analytic paths}. The
embedding is well-defined even prior to solving the diffeomorphism constraint,
at no point is a graph fixed, and at no point is the piecewise linear category
used. This motivates for the first time a definition of operators in LQC
corresponding to holonomies along non-piecewise-linear paths, without changing
the usual kinematics of LQC in any way. The new embedding intertwines all
operators corresponding to such holonomies, and all elements in its image
satisfy an operator equation which classically implies homogeneity and
isotropy. The construction is made possible by a recent result proven by
Fleischhack.
| arxiv topic:gr-qc |
arxiv_dataset-40291301.631 | One-Particle Measurement of the Antiproton Magnetic Moment
physics.atom-ph
\DeclareRobustCommand{\pbar}{\HepAntiParticle{p}{}{}\xspace}
\DeclareRobustCommand{\p}{\HepParticle{p}{}{}\xspace}
\DeclareRobustCommand{\mup}{$\mu_{p}${}{}\xspace}
\DeclareRobustCommand{\mupbar}{$\mu_{\pbar}${}{}\xspace}
\DeclareRobustCommand{\muN}{$\mu_N${}{}\xspace
For the first time a single trapped \pbar is used to measure the \pbar
magnetic moment ${\bm\mu}_{\pbar}$. The moment ${\bm\mu}_{\pbar} = \mu_{\pbar}
{\bm S}/(\hbar/2)$ is given in terms of its spin ${\bm S}$ and the nuclear
magneton (\muN) by $\mu_{\pbar}/\mu_N = -2.792\,845 \pm 0.000\,012$. The 4.4
parts per million (ppm) uncertainty is 680 times smaller than previously
realized. Comparing to the proton moment measured using the same method and
trap electrodes gives $\mu_{\pbar}/\mu_p = -1.000\,000 \pm 0.000\,005$ to 5
ppm, for a proton moment ${\bm{\mu}}_{p} = \mu_{p} {\bm S}/(\hbar/2)$,
consistent with the prediction of the CPT theorem.
| arxiv topic:physics.atom-ph |
arxiv_dataset-40301301.641 | Linear Programming Decoding of Spatially Coupled Codes
cs.IT math.IT
For a given family of spatially coupled codes, we prove that the LP threshold
on the BSC of the graph cover ensemble is the same as the LP threshold on the
BSC of the derived spatially coupled ensemble. This result is in contrast with
the fact that the BP threshold of the derived spatially coupled ensemble is
believed to be larger than the BP threshold of the graph cover ensemble as
noted by the work of Kudekar et al. (2011, 2012). To prove this, we establish
some properties related to the dual witness for LP decoding which was
introduced by Feldman et al. (2007) and simplified by Daskalakis et al. (2008).
More precisely, we prove that the existence of a dual witness which was
previously known to be sufficient for LP decoding success is also necessary and
is equivalent to the existence of certain acyclic hyperflows. We also derive a
sublinear (in the block length) upper bound on the weight of any edge in such
hyperflows, both for regular LPDC codes and for spatially coupled codes and we
prove that the bound is asymptotically tight for regular LDPC codes. Moreover,
we show how to trade crossover probability for "LP excess" on all the variable
nodes, for any binary linear code.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-40311301.651 | Zero noise limits using local times
math.PR
We consider a well-known family of SDEs with irregular drifts and the
correspondent zero noise limits. Using (mollified) local times, we show which
trajectories are selected. The approach is completely probabilistic and relies
on elementary stochastic calculus only.
| arxiv topic:math.PR |
arxiv_dataset-40321301.661 | Compressed correlation functions and fast aging dynamics in metallic
glasses
cond-mat.soft cond-mat.dis-nn
We present x-ray photon correlation spectroscopy measurements of the atomic
dynamics in a Zr67Ni33 metallic glass, well below its glass transition
temperature. We find that the decay of the density fluctuations can be well
described by compressed, thus faster than exponential, correlation functions
which can be modeled by the well-known Kohlrausch-Williams-Watts function with
a shape exponent {\beta} larger than one. This parameter is furthermore found
to be independent of both waiting time and wave-vector, leading to the
possibility to rescale all the correlation functions to a single master curve.
The dynamics in the glassy state is additionally characterized by different
aging regimes which persist in the deep glassy state. These features seem to be
universal in metallic glasses and suggest a non diffusive nature of the
dynamics. This universality is supported by the possibility of describing the
fast increase of the structural relaxation time with waiting time using a
unique model function, independently of the microscopic details of the system.
| arxiv topic:cond-mat.soft cond-mat.dis-nn |
arxiv_dataset-40331301.671 | On Supervised Selection of Bayesian Networks
cs.LG stat.ML
Given a set of possible models (e.g., Bayesian network structures) and a data
sample, in the unsupervised model selection problem the task is to choose the
most accurate model with respect to the domain joint probability distribution.
In contrast to this, in supervised model selection it is a priori known that
the chosen model will be used in the future for prediction tasks involving more
``focused' predictive distributions. Although focused predictive distributions
can be produced from the joint probability distribution by marginalization, in
practice the best model in the unsupervised sense does not necessarily perform
well in supervised domains. In particular, the standard marginal likelihood
score is a criterion for the unsupervised task, and, although frequently used
for supervised model selection also, does not perform well in such tasks. In
this paper we study the performance of the marginal likelihood score
empirically in supervised Bayesian network selection tasks by using a large
number of publicly available classification data sets, and compare the results
to those obtained by alternative model selection criteria, including empirical
crossvalidation methods, an approximation of a supervised marginal likelihood
measure, and a supervised version of Dawids prequential(predictive sequential)
principle.The results demonstrate that the marginal likelihood score does NOT
perform well FOR supervised model selection, WHILE the best results are
obtained BY using Dawids prequential r napproach.
| arxiv topic:cs.LG stat.ML |
arxiv_dataset-40341301.681 | On novel string theories from 4d gauge theories
hep-th
We investigate strings theories as defined from four dimensional gauge
theories. It is argued that novel (super)string theories exist up to 26
dimensions. Some of them may support weakly curved geometries.
| arxiv topic:hep-th |
arxiv_dataset-40351301.691 | Models of mixed hadron-quark-gluon matter
hep-ph nucl-th
The problem of the possible creation of mixed hadron-quark-gluon matter, that
can arise at nuclear or heavy-ion collisions, is addressed. It is shown that
there can exist several different kinds of such a mixed matter. The main types
of this matter can be classified onto macroscopic mixture, mesoscopic mixture,
and microscopic mixture. Different types of these mixtures require principally
different descriptions. Before comparing theoretical results with experiments,
one has to analyze thermodynamic stability of all these mixed states,
classifying them onto unstable, metastable, and stable. Only the most stable
mixed state should be compared with experiment. Mixed states also need to be
checked with regard to stratification instability. In addition to the static
stratification instability, there can happen dynamic instability occurring in a
mixture of components moving with respect to each other. This effect, called
counterflow instability, has also to be taken into account, since it can lead
to the stratification of mixed matter.
| arxiv topic:hep-ph nucl-th |
arxiv_dataset-40361301.701 | Metal silicide/poly-Si Schottky diodes for uncooled microbolometers
cond-mat.mtrl-sci physics.ins-det physics.optics
Nickel silicide Schottky diodes formed on polycrystalline Si<P> films are
proposed as temperature sensors of monolithic uncooled microbolometer IR focal
plane arrays. Structure and composition of nickel silicide/polycrystalline
silicon films synthesized in a low-temperature process are examined by means of
transmission electron microscopy. The Ni silicide is identified as multi-phase
compound composed by 20 to 40% of Ni3Si, 30 to 60% of Ni2Si and 10 to 30% of
NiSi with probable minor content of NiSi2 at the silicide/poly-Si interface.
Rectification ratios of the Schottky diodes vary from ~100 to ~20 for the
temperature increasing from 22 to 70C; they exceed 1000 at 80K. A barrier of
~0.95 eV is found to control the photovoltage spectra at room temperature. A
set of barriers is observed in photo-emf spectra at 80K and attributed to the
Ni-silicide/poly-Si interface. Absolute values of temperature coefficients of
voltage and current are found to vary from 0.3 to 0.6%/K for forward biasing
and around 2.5%/K for reverse biasing of the diodes.
| arxiv topic:cond-mat.mtrl-sci physics.ins-det physics.optics |
arxiv_dataset-40371301.711 | Entanglement-free certification of entangling gates
quant-ph
Not all quantum protocols require entanglement to outperform their classical
alternatives. The nonclassical correlations that lead to this quantum advantage
are conjectured to be captured by quantum discord. Here we demonstrate that
discord can be explicitly used as a resource: certifying untrusted entangling
gates without generating entanglement at any stage. We implement our protocol
in the single-photon regime, and show its success in the presence of high
levels of noise and imperfect gate operations. Our technique offers a practical
method for benchmarking entangling gates in physical architectures in which
only highly-mixed states are available.
| arxiv topic:quant-ph |
arxiv_dataset-40381301.721 | Detection of a multi-shell planetary nebula around the hot subdwarf
O-type star 2MASS J19310888+4324577
astro-ph.SR
(Abridged) The origin of hot subdwarf O-type stars (sdOs) remains unclear
since their discovery in 1947. Among others, a post-Asymptotic Giant Branch
(post-AGB) origin is possible for a fraction of sdOs. We are involved in a
comprehensive ongoing study to search for and to analyze planetary nebulae
(PNe) around sdOs with the aim of establishing the fraction and properties of
sdOs with a post-AGB origin. We use deep Halpha and [OIII] images of sdOs to
detect nebular emission and intermediate resolution, long-slit optical
spectroscopy of the detected nebulae and their sdO central stars. These data
are complemented with other observations for further analysis of the detected
nebulae. We report the detection of an extremely faint, complex PN around 2MASS
J19310888+4324577 (2M1931+4324), a star classified as sdO in a binary system.
The PN shows a bipolar and an elliptical shell, whose major axes are oriented
perpendicular to each other, and high-excitation structures outside the two
shells. WISE archive images show faint, extended emission at 12 and 22 microns
in the inner nebular regions. The internal nebular kinematics is consistent
with a bipolar and a cylindrical/ellipsoidal shell, in both cases with the main
axis mainly perpendicular to the line of sight. The nebular spectrum only
exhibits Halpha, Hbeta and [OIII]4959,5007 emission lines, but suggests a very
low-excitation ([OIII]/Hbeta = 1.5), in strong contrast with the absence of
low-excitation emission lines. The spectrum of 2M1931+4324 presents narrow,
ionized helium absorptions that confirm the previous sdO classification and
suggest an effective temperature >= 60000 K. The binary nature of 2M1931+4324,
its association with a complex PN, and several properties of the system provide
strong support for the idea that binary central stars are a crucial ingredient
in the formation of complex PNe.
| arxiv topic:astro-ph.SR |
arxiv_dataset-40391301.731 | Second order QCD corrections to jet production at hadron colliders: the
all-gluon contribution
hep-ph
We report the calculation of next-to-next-to-leading order (NNLO) QCD
corrections in the purely gluonic channel to dijet production and related
observables at hadron colliders. Our result represents the first NNLO
calculation of a massless jet observable at hadron colliders, and opens the
path towards precision QCD phenomenology with the LHC.
| arxiv topic:hep-ph |
arxiv_dataset-40401301.741 | Decision Theoretic Foundations of Graphical Model Selection
cs.AI
This paper describes a decision theoretic formulation of learning the
graphical structure of a Bayesian Belief Network from data. This framework
subsumes the standard Bayesian approach of choosing the model with the largest
posterior probability as the solution of a decision problem with a 0-1 loss
function and allows the use of more general loss functions able to trade-off
the complexity of the selected model and the error of choosing an
oversimplified model. A new class of loss functions, called disintegrable, is
introduced, to allow the decision problem to match the decomposability of the
graphical model. With this class of loss functions, the optimal solution to the
decision problem can be found using an efficient bottom-up search strategy.
| arxiv topic:cs.AI |
arxiv_dataset-40411301.751 | Analytic structure of one-loop coefficients
hep-ph hep-th
By the unitarity cut method, analytic expressions of one-loop coefficients
have been given in spinor forms. In this paper, we present one-loop
coefficients of various bases in Lorentz-invariant contraction forms of
external momenta. Using these forms, the analytic structure of these
coefficients becomes manifest. Firstly, coefficients of bases contain only
second-type singularities while the first-type singularities are included
inside scalar bases. Secondly, the highest degree of each singularity is
correlated with the degree of the inner momentum in the numerator. Thirdly, the
same singularities will appear in different coefficients, thus our explicit
results could be used to provide a clear physical picture under various limits
(such as soft or collinear limits) when combining contributions from all bases.
| arxiv topic:hep-ph hep-th |
arxiv_dataset-40421301.761 | Dynamical kurtosis of net and total proton distributions in STAR at RHIC
nucl-ex hep-ex
We report the energy and centrality dependence of dynamical kurtosis for Au +
Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV at
RHIC. The dynamical kurtosis of net-proton is compared to that of total-proton.
The results are also compared with AMPT model calculations.
| arxiv topic:nucl-ex hep-ex |
arxiv_dataset-40431301.771 | Studying the Peculiar Velocity Bulk Flow in a Sparse Survey of Type-Ia
SNe
astro-ph.CO
Studies of the peculiar velocity bulk flow based on different tools and
datasets have been consistent so far in their estimation of the direction of
the flow, which also happens to lie in close proximity to several features
identified in the cosmic microwave background, providing motivation to use new
compilations of type-Ia supernovae measurements to pinpoint it with better
accuracy and up to higher redshift. Unfortunately, the peculiar velocity field
estimated from the most recent Union2.1 compilation suffers from large
individual errors, poor sky coverage and low redshift-volume density. We show
that as a result, any naive attempt to calculate the best-fit bulk flow and its
significance will be severely biased. Instead, we introduce an iterative method
which calculates the amplitude and the scatter of the direction of the best-fit
bulk flow as deviants are successively removed and take into account the
sparsity of the data when estimating the significance of the result. Using 200
supernovae up to a redshift of z=0.2, we find that while the amplitude of the
bulk flow is marginally consistent with the value expected in a LCDM universe
given the large bias, the scatter of the direction is significantly low (at >=
99.5 C.L.) when compared to random simulations, supporting the quest for a
cosmological origin.
| arxiv topic:astro-ph.CO |
arxiv_dataset-40441302.006 | Collision Kernels from Velocity-Selective Optical Pumping with Magnetic
Depolarization
physics.atom-ph astro-ph.IM
We experimentally demonstrate how magnetic depolarization of
velocity-selective optical pumping can be used to single out the collisional
cusp kernel best describing spin and velocity relaxing collisions between
potassium atoms and low pressure helium. The range of pressures and transverse
fields used simulate the novel optical pumping regime pertinent to sodium
guidestars employed in adaptive optics. We measure the precession of
spin-velocity modes under the application of transverse magnetic fields,
simulating the natural configuration of mesospheric sodium optical pumping in
the geomagnetic field. We also provide a full theoretical account of the
experimental data using the recently developed cusp kernels, which
realistically quantify velocity damping collisions in this novel optical
pumping regime. A single cusp kernel with a sharpness $s=13\pm 2$ provides a
global fit to the K-He data.
| arxiv topic:physics.atom-ph astro-ph.IM |
arxiv_dataset-40451302.016 | Polyhedrality in Pieces
math.FA
The aim of this paper is to present two tools, Theorems 4 and 7, that make
the task of finding equivalent polyhedral norms on certain Banach spaces easier
and more transparent. The hypotheses of both tools are based on countable
decompositions, either of the unit sphere S_X or of certain subsets of the dual
ball of a given Banach space X. The sufficient conditions of Theorem 4 are
shown to be necessary in the separable case. Using Theorem 7, we can unify two
known results regarding the polyhedral renorming of certain C(K) spaces, and
spaces having an (uncountable) unconditional basis. New examples of spaces
having equivalent polyhedral norms are given in the final section.
| arxiv topic:math.FA |
arxiv_dataset-40461302.026 | TASI Lectures on Jet Substructure
hep-ph
Jet physics is a rich and rapidly evolving field, with many applications to
physics in and beyond the Standard Model. These notes, based on lectures
delivered at the June 2012 Theoretical Advanced Study Institute, provide an
introduction to jets at the Large Hadron Collider. Topics covered include
sequential jet algorithms, jet shapes, jet grooming, and boosted Higgs and top
tagging.
| arxiv topic:hep-ph |
arxiv_dataset-40471302.036 | On Weighted Low-Rank Approximation
stat.AP
Our main interest is the low-rank approximation of a matrix in R^m.n under a
weighted Frobenius norm. This norm associates a weight to each of the (m x n)
matrix entries. We conjecture that the number of approximations is at most
min(m, n).
We also investigate how the approximations depend on the weight-values.
| arxiv topic:stat.AP |
arxiv_dataset-40481302.046 | Is the Higgs a sign of extra dimensions?
hep-ph hep-th
We introduce a 4-dimensional cutoff in the scenario of gauge-Higgs
unification to control the ultraviolet behavior. A one-loop effective potential
for a Higgs field and the Higgs mass are obtained with the cutoff. We find an
{\it interrelation} between the 4-dimensional cutoff and the scale of extra
dimensions, which is concretized through the Higgs mass. Combining this
interrelation and the recently discovered Higgs boson at LHC, we obtain an
interesting constraint for the 4-dimensional cutoff and the extra dimensional
scale.
| arxiv topic:hep-ph hep-th |
arxiv_dataset-40491302.056 | X-ray behaviour of GRBs detected by INTEGRAL/JEM-X
astro-ph.HE astro-ph.CO
INTEGRAL's JEM-X instrument offers a very rare opportunity to observe the
full prompt X-ray emission from GRBs and the transition to the afterglow phase.
A study of prompt X-ray flares in some bursts from the INTEGRAL GRB sample and
the early X-ray post-GRB emission from 3-35 keV is presented here. Significant
post-GRB emission above 10 keV is observed for GRB 041219A and GRB 081003A.
| arxiv topic:astro-ph.HE astro-ph.CO |
arxiv_dataset-40501302.066 | Andreev experiments on superconductor/ferromagnet point contacts
cond-mat.mes-hall cond-mat.supr-con
Andreev reflection is a smart tool to investigate the spin polarisation P of
the current through point contacts between a superconductor and a ferromagnet.
We compare different models to extract P from experimental data and investigate
the dependence of P on different contact parameters.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-40511302.076 | Blowing up extremal K\"ahler manifolds II
math.DG
This is a continuation of the work of Arezzo-Pacard-Singer and the author on
blowups of extremal K\"ahler manifolds. We prove the conjecture stated in [32],
and we relate this result to the K-stability of blown up manifolds. As an
application we prove that if a K\"ahler manifold M of dimension greater than 2
admits a cscK metric, then the blowup of M at a point admits a cscK metric if
and only if it is K-stable, as long as the exceptional divisor is sufficiently
small.
| arxiv topic:math.DG |
arxiv_dataset-40521302.086 | Incompatibility of the tunneling limit with laser fields
quant-ph physics.optics
The Schwinger limit refers to longitudinal electric fields that are
sufficiently strong to "polarize the vacuum" into electron-positron pairs by a
tunneling mechanism. Laser fields are transverse electromagnetic fields for
which the Schwinger limit has no relevance. Longitudinal and transverse fields
are fundamentally different because of the different values of the
F^{{\mu}{\nu}}F_{{\mu}{\nu}} Lorentz invariant that characterizes the fields.
One aspect of this difference is the zero-frequency limit, that exists for
longitudinal fields, but is ill-defined for transverse fields. The goal of
approaching the Schwinger limit with sufficiently strong lasers is thus not a
possibility. Tunneling transition rates are characterized by an exponential
behavior of the form exp(-C/E), where E is the magnitude of the applied
electric field and C is a system-dependent constant. Searches for such behavior
within a Coulomb-gauge treatment of laser-induced processes are shown to fail.
| arxiv topic:quant-ph physics.optics |
arxiv_dataset-40531302.096 | Azimuthal correlation among jets produced in association with a bottom
or top quark pair at the LHC
hep-ph hep-ex
Angular correlation of jets produced in association with a massive scalar,
vector or tensor boson is crucial in the determination of their spin and CP
properties. We study jet angular correlations in events with a high mass bottom
quark pair or a top quark pair and two jets at the LHC, whose cross-section is
dominated by the virtual gluon fusion sub-processes when appropriate kinematic
selection cuts (vector-boson fusion cuts) are applied. We evaluate helicity
amplitudes for sub-processes initiated by qq, qg and gg collisions in the limit
where the intermediate gluons are collinear to the initial partons. We first
obtain a general expression for the azimuthal angle correlations among the
dijets and t t-bar or b b-bar, in terms of the gg to t t-bar or b b-bar
helicity amplitudes in the real gluon approximation of the full matrix
elements, and find simple analytic expressions in the two kinematic limits, the
production of a heavy quark pair near the threshold, and in the relativistic
limit where the invariant mass of the heavy quark pair is much larger than the
quark mass. For b b-bar + 2 jets we find strong azimuthal angle correlations
which are distinct from those expected for events with a CP-even or odd scalar
boson which may decay into a b b-bar pair. For t t-bar + 2 jets we find that
the angular correlations are similar to that of a CP-odd scalar+2 jets near the
threshold M_(t t-bar) ~ 2 m_t, while in the relativistic limit they resemble
the distribution for b b-bar + 2 jets. These correlations in the standard QCD
processes will help establish the experimental technique to measure the spin
and CP properties of new particles produced via gluon fusion at the LHC.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-40541302.106 | Higgs decay into two photons from a 3HDM with flavor symmetry
hep-ph
In this short letter we show that the excess of events in the decay of Higgs
to two photons reported by ATLAS and CMS can be easily accommodated in a flavor
renormalizable three Higgs doublet model (3HDM). The model is consistent with
all fermion masses, mixing angles, and flavor changing neutral current
constraints.
| arxiv topic:hep-ph |
arxiv_dataset-40551302.116 | The near-infrared spectral energy distribution of {\beta} Pictoris b
astro-ph.EP
A gas giant planet has previously been directly seen orbiting at 8-10 AU
within the debris disk of the ~12 Myr old star {\beta} Pictoris. The {\beta}
Pictoris system offers the rare opportunity to study the physical and
atmospheric properties of an exoplanet placed on a wide orbit and to establish
its formation scenario. We obtained J (1.265 {\mu}m), H (1.66 {\mu}m), and M'
(4.78 {\mu}m) band angular differential imaging of the system between 2011 and
2012. We detect the planetary companion in our four-epoch observations. We
estimate J = 14.0 +- 0.3, H = 13.5 +- 0.2, and M' = 11.0 +- 0.3 mag. Our new
astrometry consolidates previous semi-major axis (sma=8-10 AU) and excentricity
(e <= 0.15) estimates of the planet. These constraints, and those derived from
radial velocities of the star provides independent upper limits on the mass of
{\beta} Pictoris b of 12 and 15.5 MJup for semi-major axis of 9 and 10 AU. The
location of {\beta} Pictoris b in color-magnitude diagrams suggests it has
spectroscopic properties similar to L0-L4 dwarfs. This enables to derive
Log10(L/Lsun) = -3.87 +- 0.08 for the companion. The analysis with 7
PHOENIX-based atmospheric models reveals the planet has a dusty atmosphere with
Teff = 1700 +- 100 K and log g = 4.0+- 0.5. "Hot-start" evolutionary models
give a new mass of 10+3-2 MJup from Teff and 9+3-2 MJup from luminosity.
Predictions of "cold-start" models are inconsistent with independent
constraints on the planet mass. "Warm-start" models constrain the mass to M >=
6MJup and the initial entropies to values (Sinit >= 9.3Kb/baryon), intermediate
between those considered for cold/hot-start models, but likely closer to those
of hot-start models.
| arxiv topic:astro-ph.EP |
arxiv_dataset-40561302.126 | Geometry of the momentum space: From wire networks to quivers and
monopoles
math-ph math.MP
A new nano--material in the form of a double gyroid has motivated us to study
(non-commutative $C^*$ geometry of periodic wire networks and the associated
graph Hamiltonians. Here we present the general abstract framework, which is
given by certain quiver representations, with special attention to the original
case of the gyroid as well as related cases, such as graphene. In these
geometric situations, the non- commutativity is introduced by a constant
magnetic field and the theory splits into two pieces: commutative and
non-commutative, both of which are governed by a $C^*$ geometry.
In the non-commutative case, we can use tools such as K-theory to make
statements about the band structure. In the commutative case, we give geometric
and algebraic methods to study band intersections; these methods come from
singularity theory and representation theory. We also provide new tools in the
study, using $K$-theory and Chern classes. The latter can be computed using
Berry connection in the momentum space. This brings monopole charges and issues
of topological stability into the picture.
| arxiv topic:math-ph math.MP |
arxiv_dataset-40571302.136 | Quantitative Determination of the Band-Gap of WS2 with Ambipolar Ionic
Liquid-Gated Transistors
cond-mat.mes-hall
We realized ambipolar Field-Effect Transistors by coupling exfoliated thin
flakes of tungsten disulphide (WS2) with an ionic liquid-dielectric. The
devices show ideal electrical characteristics, including very steep
sub-threshold slopes for both electrons and holes and extremely low OFF-state
currents. Thanks to these ideal characteristics, we determine with high
precision the size of the band-gap of WS2 directly from the gate-voltage
dependence of the source-drain current. Our results demonstrate how a careful
use of ionic liquid dielectrics offers a powerful strategy to study
quantitatively the electronic properties of nano-scale materials.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-40581302.146 | Statistical Analysis of Current Sheets in Three-Dimensional
Magnetohydrodynamic Turbulence
astro-ph.HE physics.plasm-ph physics.space-ph
We develop a framework for studying the statistical properties of current
sheets in numerical simulations of 3D magnetohydrodynamic (MHD) turbulence. We
describe an algorithm that identifies current sheets in a simulation snapshot
and then determines their geometrical properties (including length, width, and
thickness) and intensities (peak current density and total energy dissipation
rate). We then apply this procedure to simulations of reduced MHD turbulence
and perform a statistical analysis on the obtained population of current
sheets. We evaluate the role of reconnection by separately studying the
populations of current sheets which contain magnetic X-points and those which
do not. We find that the statistical properties of the two populations are
different in general. We compare the scaling of these properties to
phenomenological predictions obtained for the inertial range of MHD turbulence.
Finally, we test whether the reconnecting current sheets are consistent with
the Sweet-Parker model.
| arxiv topic:astro-ph.HE physics.plasm-ph physics.space-ph |
arxiv_dataset-40591302.156 | A Target Classification Decision Aid
cs.AI
A submarine's sonar team is responsible for detecting, localising and
classifying targets using information provided by the platform's sensor suite.
The information used to make these assessments is typically uncertain and/or
incomplete and is likely to require a measure of confidence in its reliability.
Moreover, improvements in sensor and communication technology are resulting in
increased amounts of on-platform and off-platform information available for
evaluation. This proliferation of imprecise information increases the risk of
overwhelming the operator. To assist the task of localisation and
classification a concept demonstration decision aid (Horizon), based on
evidential reasoning, has been developed. Horizon is an information fusion
software package for representing and fusing imprecise information about the
state of the world, expressed across suitable frames of reference. The Horizon
software is currently at prototype stage.
| arxiv topic:cs.AI |
arxiv_dataset-40601302.166 | Non-adiabatic time-dependent density functional theory of the impurity
resistivity of metals
cond-mat.str-el
We make use of the time-dependent density functional theory to derive a new
formally exact expression for the dc resistivity of metals with impurities.
This expression takes fully into account the dynamics of electron-electron
interactions. Correction to the conventional $T$-matrix (phase-shifts) theory
is treated within hydrodynamics of inhomogeneous viscous electron liquid. As a
first application, we present calculations of the residual resistivity of
aluminum as a function of the atomic number of the impurities. We show that the
inclusion of many-body corrections considerably improves the agreement between
theory and experiment.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-40611302.176 | Galaxy rotation curves in $f(R,\phi)$-gravity
gr-qc astro-ph.CO hep-th
We investigate the possibility to explain theoretically the galaxy rotation
curves by a gravitational potential in total absence of dark matter. To this
aim an analytic fourth-order theory of gravity, nonminimally coupled with a
massive scalar field is considered. Specifically, the interaction term is given
by an analytic function $f(R,\phi)$ where $R$ is the Ricci scalar and $\phi$ is
the scalar field. The gravitational potential is generated by a point-like
source and compared with the so called Sanders's potential that can be exactly
reproduced in this case. This result means that the problem of dark matter in
spiral galaxies could be fully addressed by revising general relativity at
galactic scales and requiring further gravitational degrees of freedom instead
of new material components that have not been found out up to now.
| arxiv topic:gr-qc astro-ph.CO hep-th |
arxiv_dataset-40621302.186 | On cosmic hair and "de Sitter breaking" in linearized quantum gravity
gr-qc hep-th
We quantize linearized Einstein-Hilbert gravity on de Sitter backgrounds in a
covariant gauge. We verify the existence of a maximally-symmetric (i.e.de
Sitter-invariant) Hadamard state $\Omega$ for all globally hyperbolic de Sitter
backgrounds in all spacetime dimensions $D \ge 4$ by constructing the state's
2-point function in closed form. This 2-pt function is explicitly maximally
symmetric. We prove an analogue of the Reeh-Schlieder theorem for linearized
gravity. Using these results we prove a cosmic no-hair theorem for linearized
gravitons: for any state in the Hilbert space constructed from $\Omega$, the
late-time behavior of local observable correlation functions reduces to those
of $\Omega$ at an exponential rate with respect to proper time. We also provide
the explicitly maximally-symmetric graviton 2-pt functions in a class of
generalized de Donder gauges suitable for use in non-linear perturbation
theory. Along the way we clarify a few technical aspects which led previous
authors to conclude that these 2-pt functions do not exist.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-40631302.196 | Electronic structure, phonon spectra and electron-phonon interaction in
HfB2
cond-mat.supr-con
The electronic structure, Fermi surface, angle dependence of the cyclotron
masses and extremal cross sections of the Fermi surface, phonon spectra,
electron-phonon Eliashberg and transport spectral functions, temperature
dependence of electrical resistivity of the HfB2 diboride were investigated
from first principles using the fully relativistic and full potential linear
muffin-tin orbital methods. The calculations of the dynamic matrix were carried
out within the framework of the linear response theory. A good agreement with
experimental data of electron-phonon spectral functions, electrical
resistivity, cyclotron masses and extremal cross sections of the Fermi surface
was achieved.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-40641302.206 | Tests For Complete Positivity of Quantum Channels
quant-ph
A quantum channel will have a Choi representation from which the complete
positivity (CP) can be determined in a number of different ways. Every method
relies on Choi's proof which relates CP to the positive semi-definiteness of a
specially constructed matrix (i.e. the "Choi representation of the channel").
It can be shown that different CP tests can be used in different situations to
avoid the computationally expensive brute force method of calculating the full
spectrum of the Choi representation, which is the traditional method for
testing whether or not a channel is CP. It is important to have quick, reliable
analytical and computational tests for CP as negative channels become more
prevalent in the study of quantum information.
| arxiv topic:quant-ph |
arxiv_dataset-40651302.216 | Superconducting Transition Temperatures for Spin-Fluctuation Promoted
Superconductivity in Heavy Fermion Compounds
cond-mat.supr-con
The quantum critical Antiferromagnetic (AFM) fluctuation spectra measured by
inelastic neutron scattering recently in two heavy fermion superconductors are
used together with their other measured properties to calculate their D-wave
superconducting transition temperatures $T_{\rm c}$. To this end, the
linearized Eliashberg equations for D-wave superconductivity induced by AFM
fluctuations are solved in models of fermions with various levels of nesting.
The results for the ratio of $T_{\rm c}$ to the characteristic spin-fluctuation
energy are well parametrized by a dimensionless coupling constant and the AFM
correlation length. Comparing the results with experiments suggests that one
may reasonably conclude that superconductivity in these compounds is indeed
caused by AFM fluctuations. This conclusion is strengthened by a calculation
with the same parameters of the measured coefficient of the normal state
quantum-critical resistivity $\propto T^{3/2}$ characteristic of {\it gaussian}
AFM quantum-critical fluctuations. The calculations give details of the
superconducting coupling as a function of the correlation length and the
integrated fluctuation spectra useful in other compounds.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-40661302.226 | Semiclassical inverse spectral theory for singularities of focus-focus
type
math-ph math.MP math.SG math.SP
We prove, assuming that the Bohr-Sommerfeld rules hold, that the joint
spectrum near a focus-focus critical value of a quantum integrable system
determines the classical Lagrangian foliation around the full focus-focus leaf.
The result applies, for instance, to h-pseudodifferential operators, and to
Berezin-Toeplitz operators on prequantizable compact symplectic manifolds.
| arxiv topic:math-ph math.MP math.SG math.SP |
arxiv_dataset-40671302.236 | Nambu sum rule in the NJL models: from superfluidity to top quark
condensation
hep-ph cond-mat.supr-con
It may appear that the recently found resonance at 125 GeV is not the only
Higgs boson. We point out the possibility that the Higgs bosons appear in
models of top-quark condensation, where the masses of the bosonic excitations
are related to the top quark mass by the sum rule similar to the Nambu sum rule
of the NJL models \cite{Nambu}. This rule was originally considered by Nambu
for superfluid $^3$He-B and for the BCS model of superconductivity. It relates
the two masses of bosonic excitations existing in each channel of Cooper
pairing to the fermion mass. An example of the Nambu partners is provided by
the amplitude and the phase modes in the BCS model describing Cooper pairing in
the s-wave channel. This sum rule suggests the existence of the Nambu partners
for the 125 GeV Higgs boson. Their masses can be predicted by the Nambu sum
rule under certain circumstances. For example, if there are only two states in
the given channel, the mass of the Nambu partner is $\sim$ 325 GeV. They
together satisfy the Nambu sum rule $M_1^2 + M_2^2 = 4 M_t^2$, where $M_t \sim
$174 GeV is the mass of the top quark. If there are two doubly degenerated
states, then the second mass is $\sim$ 210 GeV. In this case the Nambu sum rule
is $2 M_1^2 + 2 M_2^2 = 4 M_t^2$. In addition, the properties of the Higgs
modes in superfluid $^3$He-A, where the symmetry breaking is similar to that of
the Standard Model of particle physics, suggest the existence of two
electrically charged Higgs particles with masses around 245 GeV, which together
also obey the Nambu sum rule $M_+^2 + M_-^2 = 4 M_t^2$.
| arxiv topic:hep-ph cond-mat.supr-con |
arxiv_dataset-40681302.246 | Scheme of 2-dimensional atom localization for a three-level atom via
quantum coherence
quant-ph
We present a scheme for two-dimensional (2D) atom localization in a
three-level atomic system. The scheme is based on quantum coherence via
classical standing wave fields between the two excited levels. Our results show
that conditional position probability is significantly phase dependent of the
applied field and frequency detuning of spontaneously emitted photons. We
obtain a single localization peak having probability close to unity by
manipulating the control parameters. The effect of atomic level coherence on
the sub-wavelength localization has also been studied. Our scheme may be
helpful in systems involving atom-field interaction.
| arxiv topic:quant-ph |
arxiv_dataset-40691302.256 | Hamiltonian dynamics of several rigid bodies interacting with point
vortices
physics.flu-dyn math-ph math.MP
We derive the dynamics of several rigid bodies of arbitrary shape in a
2-dimensional inviscid and incompressible fluid, whose vorticity field is given
by point vortices. We adopt the idea of Vankerschaver et al. (2009) to derive
the Hamiltonian formulation via symplectic reduction from a canonical
Hamiltonian system. The reduced system is described by a non-canonical
symplectic form, which has previously been derived for a single, circular disk
using heavy differential-geometric machinery in an infinite-dimensional
setting. In contrast, our derivation makes use of the fact that the dynamics of
the fluid, and thus the point vortex dynamics, is determined from first
principles. Using this knowledge we can directly determine the dynamics on the
reduced, finite-dimensional phase space, using only classical mechanics.
Furthermore, our approach easily handles several bodies of arbitrary shapes.
From the Hamiltonian description we derive a Lagrangian formulation, which
enables the system for variational time integrators. We briefly describe how to
implement such a numerical scheme and simulate different configurations for
validation.
| arxiv topic:physics.flu-dyn math-ph math.MP |
arxiv_dataset-40701302.266 | Fabrication of high quality sub-micron Au gratings over large areas with
pulsed laser interference lithography for SPR sensors
physics.optics
Metallic gratings were fabricated using high energy laser interference
lithography with a frequency tripled Nd:YAG nanosecond laser. The grating
structures were first recorded in a photosensitive layer and afterwards
transferred to an Au film. High quality Au gratings with a period of 770 nm and
peak-to-valley heights of 20-60 nm exhibiting plasmonic resonance response were
successfully designed, fabricated and characterized.
| arxiv topic:physics.optics |
arxiv_dataset-40711302.276 | The transition towards immortality: non-linear autocatalytic growth of
citations to scientific papers
physics.soc-ph cond-mat.stat-mech cs.DL
We discuss microscopic mechanisms of complex network growth, with the special
emphasis of how these mechanisms can be evaluated from the measurements on real
networks. As an example we consider the network of citations to scientific
papers. Contrary to common belief that its growth is determined by the linear
preferential attachment, our microscopic measurements show that it is driven by
the nonlinear autocatalytic growth. This invalidates the scale-free hypothesis
for the citation network. The nonlinearity is responsible for a dramatic
dynamical phase transition: while the citation lifetime of majority of papers
is 6-10 years, the highly-cited papers have practically infinite lifetime.
| arxiv topic:physics.soc-ph cond-mat.stat-mech cs.DL |
arxiv_dataset-40721302.286 | Temporal variations of X-ray solar flare loops: length, corpulence,
position, temperature, plasma pressure and spectra
astro-ph.SR astro-ph.HE
The spatial and spectral properties of three solar flare coronal X-ray loops
are studied before, during and after the peak X-ray emission. Using
observations from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI),
we deduce the temporal changes in emitting X-ray length, corpulence, volume,
position, number density and thermal pressure. We observe a decrease in the
loop length, width and volume before the X-ray peak, and an increasing number
density and thermal pressure. After the X-ray peak, volume increases and loop
corpulence grows due to an increasing width. The volume variations are more
pronounced than the position variations, often known as magnetic line
contraction. We believe this is the first dedicated study of the temporal
evolution of X-ray loop lengths and widths. Collectively, the observations also
show for the first time three temporal phases given by peaks in temperature,
X-ray emission and thermal pressure, with minimum volume coinciding with the
X-ray peak. Although the volume of the flaring plasma decreases before the peak
in X-ray emission, the relationship between temperature and volume does not
support simple compressive heating in a collapsing magnetic trap model. Within
a low beta plasma, shrinking loop widths perpendicular to the guiding field can
be explained by squeezing the magnetic field threading the region. Plasma
heating leads to chromospheric evaporation and growing number density,
producing increasing thermal pressure and decreasing loop lengths as electrons
interact at shorter distances and we believe after the X-ray peak, the
increasing loop corpulence.
| arxiv topic:astro-ph.SR astro-ph.HE |
arxiv_dataset-40731302.296 | Towards Quantifying the electrostatic transduction mechanism in carbon
nanotube molecular sensors
cond-mat.mtrl-sci
Despite the great promise of carbon nanotube field effect transistors (CNT
FETs) for applications in chemical and biochemical detection, a quantitative
understanding of sensor responses is lacking. To explore the role of
electrostatics in sensor transduction, experiments were conducted with a set of
highly similar compounds designed to adsorb onto the CNT FET via a pyrene
linker group and take on a set of known charge states under ambient conditions.
Acidic and basic species were observed to induce threshold voltage shifts of
opposite sign, consistent with gating of the CNT FET by local charges due to
protonation or deprotonation of pyrene compounds by interfacial water. The
magnitude of the gate voltage shift was controlled by the distance between the
charged group and the CNT. Additionally, functionalization with an un-charged
pyrene compound showed a threshold shift ascribed to its molecular dipole
moment. This work illustrates a method to produce CNT FETs with controlled
values of the turnoff gate voltage, and more generally, these results will
inform the development of quantitative models for the response of CNT FET
chemical and biochemical sensors.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-40741302.306 | Kirillov models and the Breuil-Schneider conjecture for GL_2(F)
math.RT math.NT
Let F be a local field of characteristic 0. The Breuil-Schneider conjecture
for GL_2(F) predicts which locally algebraic representations of this group
admit an integral structure. We extend the methods of [K-dS12], which treated
smooth representations only, to prove the conjecture for some locally algebraic
representations as well.
| arxiv topic:math.RT math.NT |
arxiv_dataset-40751302.316 | A New Construction of Multi-receiver Authentication Codes from
Pseudo-Symplectic Geometry over Finite Fields
cs.IT math.IT
Multi-receiver authentication codes allow one sender to construct an
authenticated message for a group of receivers such that each receiver can
verify authenticity of the received message. In this paper, we constructed one
multi-receiver authentication codes from pseudo-symplectic geometry over finite
fields. The parameters and the probabilities of deceptions of this codes are
also computed.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-40761302.326 | Measuring Black Hole Spin using X-ray Reflection Spectroscopy
astro-ph.HE gr-qc
I review the current status of X-ray reflection (a.k.a. broad iron line)
based black hole spin measurements. This is a powerful technique that allows us
to measure robust black hole spins across the mass range, from the stellar-mass
black holes in X-ray binaries to the supermassive black holes in active
galactic nuclei. After describing the basic assumptions of this approach, I lay
out the detailed methodology focusing on "best practices" that have been found
necessary to obtain robust results. Reflecting my own biases, this review is
slanted towards a discussion of supermassive black hole (SMBH) spin in active
galactic nuclei (AGN). Pulling together all of the available XMM-Newton and
Suzaku results from the literature that satisfy objective quality control
criteria, it is clear that a large fraction of SMBHs are rapidly-spinning,
although there are tentative hints of a more slowly spinning population at high
(M>5*10^7Msun) and low (M<2*10^6Msun) mass. I also engage in a brief review of
the spins of stellar-mass black holes in X-ray binaries. In general,
reflection-based and continuum-fitting based spin measures are in agreement,
although there remain two objects (GROJ1655-40 and 4U1543-475) for which that
is not true. I end this review by discussing the exciting frontier of
relativistic reverberation, particularly the discovery of broad iron line
reverberation in XMM-Newton data for the Seyfert galaxies NGC4151, NGC7314 and
MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk
reflection, this detection of reverberation demonstrates that future large-area
X-ray observatories such as LOFT will make tremendous progress in studies of
strong gravity using relativistic reverberation in AGN.
| arxiv topic:astro-ph.HE gr-qc |
arxiv_dataset-40771302.336 | Lower bounds for the circuit size of partially homogeneous polynomials
cs.CC math.AC math.LO
In this paper we associate to each multivariate polynomial $f$ that is
homogeneous relative to a subset of its variables a series of polynomial
families $P_\lambda (f)$ of $m$-tuples of homogeneous polynomials of equal
degree such that the circuit size of any member in $P_\lambda (f)$ is bounded
from above by the circuit size of $f$. This provides a method for obtaining
lower bounds for the circuit size of $f$ by proving $(s,r)$-(weak) elusiveness
of the polynomial mapping associated with $P_\lambda (f)$. We discuss some
algebraic methods for proving the $(s,r)$-(weak) elusiveness. We also improve
estimates in the normal homogeneous-form of an arithmetic circuit obtained by
Raz in \cite{Raz2009} which results in better lower bounds for circuit size
(Lemma \ref{lem:cor38}, Remark \ref{rem:cor38}).
Our methods yield non-trivial lower bound for the circuit size of several
classes of multivariate homogeneous polynomials (Corollary \ref{cor:412},
Example \ref{ex:bi}).
| arxiv topic:cs.CC math.AC math.LO |
arxiv_dataset-40781302.346 | On applications of Orlicz Spaces to Statistical Physics
math-ph math.MP
We present a new rigorous approach based on Orlicz spaces for the description
of the statistics of large regular statistical systems, both classical and
quantum. This approach has the advantage that statistical mechanics is much
better settled. In particular, a new kind of renormalization leading to states
having a well defined entropy function is presented.
| arxiv topic:math-ph math.MP |
arxiv_dataset-40791302.356 | Arguing for Decisions: A Qualitative Model of Decision Making
cs.AI
We develop a qualitative model of decision making with two aims: to describe
how people make simple decisions and to enable computer programs to do the
same. Current approaches based on Planning or Decisions Theory either ignore
uncertainty and tradeoffs, or provide languages and algorithms that are too
complex for this task. The proposed model provides a language based on rules, a
semantics based on high probabilities and lexicographical preferences, and a
transparent decision procedure where reasons for and against decisions
interact. The model is no substitude for Decision Theory, yet for decisions
that people find easy to explain it may provide an appealing alternative.
| arxiv topic:cs.AI |
arxiv_dataset-40801302.366 | On Zero Delay Source-Channel Coding
cs.IT math.IT
In this paper, we study the zero-delay source-channel coding problem, and
specifically the problem of obtaining the vector transformations that optimally
map between the m-dimensional source space and the k-dimensional channel space,
under a given transmission power constraint and for the mean square error
distortion. We first study the functional properties of this problem and show
that the objective is concave in the source and noise densities and convex in
the density of the input to the channel. We then derive the necessary
conditions for optimality of the encoder and decoder mappings. A well known
result in information theory pertains to the linearity of optimal encoding and
decoding mappings in the scalar Gaussian source and channel setting, at all
channel signal-to-noise ratios (CSNRs). In this paper, we study this result
more generally, beyond the Gaussian source and channel, and derive the
necessary and sufficient condition for linearity of optimal mappings, given a
noise (or source) distribution, and a specified power constraint. We also prove
that the Gaussian source-channel pair is unique in the sense that it is the
only source-channel pair for which the optimal mappings are linear at more than
one CSNR values. Moreover, we show the asymptotic linearity of optimal mappings
for low CSNR if the channel is Gaussian regardless of the source and, at the
other extreme, for high CSNR if the source is Gaussian, regardless of the
channel. Our numerical results show strict improvement over prior methods. The
numerical approach is extended to the scenario of source-channel coding with
decoder side information. The resulting encoding mappings are shown to be
continuous relatives of, and in fact subsume as special case, the Wyner-Ziv
mappings encountered in digital distributed source coding systems.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-40811302.376 | Exact Kahler Potential for Calabi-Yau Fourfolds
hep-th
We study quantum Kahler moduli space of Calabi-Yau fourfolds. Our analysis is
based on the recent work by Jockers et al. which gives a novel method to
compute the Kahler potential on the quantum Kahler moduli space of Calabi-Yau
manifold. In contrast to Calabi-Yau threefold, the quantum nature of higher
dimensional Calabi-Yau manifold is yet to be fully elucidated. In this paper we
focus on the Calabi-Yau fourfold. In particular, we conjecture the explicit
form of the quantum-corrected Kahler potential. We also compute the genus zero
Gromov-Witten invariants and test our conjecture by comparing the results with
predictions from mirror symmetry. Local toric Calabi-Yau varieties are also
discussed.
| arxiv topic:hep-th |
arxiv_dataset-40821302.386 | ScalienDB: Designing and Implementing a Distributed Database using Paxos
cs.DB cs.DC
ScalienDB is a scalable, replicated database built on top of the Paxos
algorithm. It was developed from 2010 to 2012, when the startup backing it
failed. This paper discusses the design decisions of the distributed database,
describes interesting parts of the C++ codebase and enumerates lessons learned
putting ScalienDB into production at a handful of clients. The source code is
available on Github under the AGPL license, but it is no longer developed or
maintained.
| arxiv topic:cs.DB cs.DC |
arxiv_dataset-40831302.396 | Earth Inner Core Periodic Motion due to Pressure Difference Induced by
Tidal Acceleration
astro-ph.EP
The inner structure of the earth is still a topic of discussion. Seismic
measurements showed a structure of solid, liquid, solid which describes the
mantle, outer core and inner core with the inner core in the center. The
analysis of waveform doublets suggests now that the inner core is out of center
and even of faster rotation than the mantel and crust. From the sum of Buoyancy
and Gravity on the earth inner core, the position energy is plotted and
together with the tangential tidal acceleration, it is derived that Earth Inner
Core cannot be in a center position without additional force. The Earth Core
System is explained as Hydrodynamic Bearing. The tidal acceleration is
identified as the reason for the periodic motion of the inner core and certain
frequencies of nutation. The Eccentricities out of nutation due to the effects
from the sun and moon are calculated as an approximation.
| arxiv topic:astro-ph.EP |
arxiv_dataset-40841302.406 | Raman Studies of Anisotropic Magnetic Excitations in Fluctuating Nematic
Striped La2-xSrxCuO4 and the Comparison to Uniform Nd2-xCexCuO4
cond-mat.supr-con
The mechanism of the high temperature hole-doped superconductivity was
investigated by Raman scattering. The Raman selection rule is unique, so that
anisotropic magnetic excitations in a fluctuating spin-charge stripe can be
detected as if it is static. We use different Raman selection rules for two
kinds of magnetic Raman scattering processes, two-magnon scattering and
high-energy electronic scattering. In order to confirm the difference, the
Raman spectra of striped La2-xSrxCuO4 (LSCO) and non-striped Nd2-xCexCuO4
(NCCO) were compared. The main results in LSCO are (1) magnetic excitations are
presented by individual energy dispersions for the k\parallel stripe and the
k\perp stripe, (2) the charge transfer is allowed only in the direction
perpendicular to the stripe. The direction is the same as the Burgers vector of
an edge dislocation. Hence we assume that a charge moves together with the edge
dislocation of the charge stripe. The superconducting coherence length is close
to the inter-charge stripe distance at x < 0.2. Therefore we propose a model
that superconducting pairs are formed in the edge dislocations. The binding
energy is related to the stripe formation energy.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-40851302.416 | Simple method of light-shift suppression in optical pumping systems
physics.atom-ph
We report a simple method to suppress the light shift in optical pumping
systems. This method uses only frequency modulation of a radio frequency or
microwave source, which is used to excite an atomic resonance, to
simultaneously lock the source frequency to the atomic resonance and lock the
pumping light frequency to suppress the light shift. We experimentally validate
the method in a vapor-cell atomic clock and verify the results through
numerical simulation. This technique can be applied to many optical pumping
systems that experience light shifts. It is especially useful for atomic
frequency standards because it improves long-term performance, reduces the
influence of the laser, and requires less equipment than previous methods.
| arxiv topic:physics.atom-ph |
arxiv_dataset-40861302.426 | Non-Markovian qubit dynamics induced by Coulomb crystals
quant-ph
We investigate the back-flow of information in a system with a second-order
structural phase transition, namely a quasi one-dimensional Coulomb crystal.
Using standard Ramsey interferometry which couples a target ion (the system) to
the rest of the chain (a phononic environment), we study the non-Markovian
character of the resulting open system dynamics. We study two different
time-scales and show that the back-flow of information pinpoints both the phase
transition and different dynamical features of the chain as it approaches
criticality. We also establish an exact link between the back-flow of
information and the Ramsey fringe visibility.
| arxiv topic:quant-ph |
arxiv_dataset-40871302.436 | On positive embeddings of C(K) spaces
math.FA
We investigate isomorphic embeddings $T: C(K)\to C(L)$ between Banach spaces
of continuous functions. We show that if such an embedding $T$ is a positive
operator then $K$ is an image of $L$ under a upper semicontinuous set-function
having finite values. Moreover we show that $K$ has a $\pi$-base of sets which
closures a continuous images of compact subspaces of $L$. Our results imply in
particular that if $C(K)$ can be positively embedded into $C(L)$ then some
topological properties of $L$, such as countable tightness of Frechetness, pass
to the space $K$. We show that some arbitrary isomorphic embeddings $C(K)\to
C(L)$ can be, in a sense, reduced to positive embeddings.
| arxiv topic:math.FA |
arxiv_dataset-40881302.446 | Magnetization and phase transition induced by circularly polarized laser
in quantum magnets
cond-mat.str-el
We theoretically predict a nonequilibrium phase transition in quantum spin
systems induced by a laser, which provides a purely quantum-mechanical way of
coherently controlling magnetization. Namely, when a circularly polarized laser
is applied to a spin system, the magnetic component of a laser is shown to
induce a magnetization normal to the plane of polarization, leading to an
ultrafast phase transition. We first demonstrate this phenomenon numerically
for an $S=1$ antiferromagnetic Heisenberg spin chain, where a new state emerges
with magnetization perpendicular to the polarization plane of the laser in
place of the topologically ordered Haldane state. We then elucidate its
physical mechanism by mapping the system to an effective static model. The
theory also indicates that the phenomenon should occur in general quantum spin
systems with a magnetic anisotropy. The required laser frequency is in the
terahertz range, with the required intensity being within a prospective
experimental feasibility.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-40891302.456 | Topological phases in two-dimensional arrays of parafermionic zero modes
cond-mat.str-el cond-mat.mes-hall
It has recently been realized that zero modes with projective non-Abelian
statistics, generalizing the notion of Majorana bound states, may exist at the
interface between a superconductor and a ferromagnet along the edge of a
fractional topological insulator (FTI). Here we study two-dimensional
architectures of these non-Abelian zero modes, whose interactions are generated
by the charging and Josephson energies of the superconductors. We derive
low-energy Hamiltonians for two different arrays of FTIs on the plane,
revealing an interesting interplay between the real-space geometry of the
system and its topological properties. On the one hand, in a geometry where the
length of the FTI edges is independent on the system size, the array has a
topologically ordered phase, giving rise to a qudit toric code Hamiltonian in
perturbation theory. On the other hand, in a geometry where the length of the
edges scales with system size, we find an exact duality to an Abelian lattice
gauge theory and no topological order.
| arxiv topic:cond-mat.str-el cond-mat.mes-hall |
arxiv_dataset-40901302.466 | Compressive Classification
cs.IT math.IT
This paper derives fundamental limits associated with compressive
classification of Gaussian mixture source models. In particular, we offer an
asymptotic characterization of the behavior of the (upper bound to the)
misclassification probability associated with the optimal Maximum-A-Posteriori
(MAP) classifier that depends on quantities that are dual to the concepts of
diversity gain and coding gain in multi-antenna communications. The diversity,
which is shown to determine the rate at which the probability of
misclassification decays in the low noise regime, is shown to depend on the
geometry of the source, the geometry of the measurement system and their
interplay. The measurement gain, which represents the counterpart of the coding
gain, is also shown to depend on geometrical quantities. It is argued that the
diversity order and the measurement gain also offer an optimization criterion
to perform dictionary learning for compressive classification applications.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-40911302.476 | Predicting Intermediate Storage Performance for Workflow Applications
cs.DC cs.PF
Configuring a storage system to better serve an application is a challenging
task complicated by a multidimensional, discrete configuration space and the
high cost of space exploration (e.g., by running the application with different
storage configurations). To enable selecting the best configuration in a
reasonable time, we design an end-to-end performance prediction mechanism that
estimates the turn-around time of an application using storage system under a
given configuration. This approach focuses on a generic object-based storage
system design, supports exploring the impact of optimizations targeting
workflow applications (e.g., various data placement schemes) in addition to
other, more traditional, configuration knobs (e.g., stripe size or replication
level), and models the system operation at data-chunk and control message
level.
This paper presents our experience to date with designing and using this
prediction mechanism. We evaluate this mechanism using micro- as well as
synthetic benchmarks mimicking real workflow applications, and a real
application.. A preliminary evaluation shows that we are on a good track to
meet our objectives: it can scale to model a workflow application run on an
entire cluster while offering an over 200x speedup factor (normalized by
resource) compared to running the actual application, and can achieve, in the
limited number of scenarios we study, a prediction accuracy that enables
identifying the best storage system configuration.
| arxiv topic:cs.DC cs.PF |
arxiv_dataset-40921302.486 | Subsonic Free Surface Waves in Linear Elasticity
math-ph math.MP
For general anisotropic linear elastic solids with smooth boundaries,
Rayleigh-type surface waves are studied. Using spectral factorizations of
matrix polynomials, a self-contained exposition of the case of a homogeneous
half-space is given first. The main result is about inhomogeneous anisotropic
bodies with curved surfaces. The existence of subsonic free surface waves is
shown by giving ray series asymptotic expansions, including formulas for the
transport equation.
| arxiv topic:math-ph math.MP |
arxiv_dataset-40931302.496 | Reasoning, Metareasoning, and Mathematical Truth: Studies of Theorem
Proving under Limited Resources
cs.AI
In earlier work, we introduced flexible inference and decision-theoretic
metareasoning to address the intractability of normative inference. Here,
rather than pursuing the task of computing beliefs and actions with decision
models composed of distinctions about uncertain events, we examine methods for
inferring beliefs about mathematical truth before an automated theorem prover
completes a proof. We employ a Bayesian analysis to update belief in truth,
given theorem-proving progress, and show how decision-theoretic methods can be
used to determine the value of continuing to deliberate versus taking immediate
action in time-critical situations.
| arxiv topic:cs.AI |
arxiv_dataset-40941302.506 | Fermionic Corrections to Fluid Dynamics from BTZ Black Hole
hep-th gr-qc
We reconstruct the complete fermionic orbit of the non-extremal BTZ black
hole by acting with finite supersymmetry transformations. The solution
satisfies the exact supergravity equations of motion to all orders in the
fermonic expansion and the final result is given in terms of fermionic
bilinears. By fluid/gravity correspondence, we derive linearized Navier-Stokes
equations and a set of new differential equations from Rarita-Schwinger
equation. We compute the boundary energy-momentum tensor and we interpret the
result as a perfect fluid with a modified definition of fluid velocity.
Finally, we derive the modified expression for the entropy of the black hole in
terms of the fermionic bilinears.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-40951302.516 | ATCA survey of water masers in the Large Magellanic Cloud
astro-ph.GA
We have analysed archival data taken with the Australia Telescope Compact
Array (ATCA) during 2001--2003 and detected nine new interstellar and
circumstellar water masers in the LMC. This takes the total number of star
formation water masers in the LMC to 23, spread over 14 different star forming
regions and three evolved stars. Three water maser sources (N105a/MC23,
N113/MC24, N157a/MC74) have been detected in all the previous observations that
targeted these sites, although all show significant variability on timescales
of decades. The total number of independent water maser sources now known in
the LMC means that through very long baseline interferometry astrometric
measurements it will be possible to construct a more precise model of the
galactic rotation of the LMC and its orbital motion around the Milky Way
Galaxy.
| arxiv topic:astro-ph.GA |
arxiv_dataset-40961302.526 | An incomplete model of RRATs and of nulls mode-changes and subpulses
astro-ph.HE
A model for pulsars with polar-cap magnetic flux density B antiparallel with
rotational spin is described. It recognizes the significance of two elementary
processes, proton production in electromagnetic showers and photoelectric
transitions in ions accelerated through the blackbody radiation field, which
must be present at the polar cap in the antiparallel case, but not for pulsars
of the opposite spin direction. The two populations are likely to be
indistinguishable observationally until curvature radiation pair creation
ceases to be possible. The model generates, and provides a physically realistic
framework for, the polar-cap potential fluctuations and their time-scales that
can produce mode-changes and nulls. The RRATs are then no more than an extreme
case of the more commonly observed nulls. The model is also able to support the
basic features of subpulse drift and to some extent the null-memory phenomenon
that is associated with it. Unfortunately, it appears that the most important
neutron-star parameter for quantitative predictive purposes is the
whole-surface temperature, a quantity which is not readily observable at the
neutron-star ages concerned.
| arxiv topic:astro-ph.HE |
arxiv_dataset-40971302.536 | Probing hot electron transport across an epitaxial Schottky interface of
SrRuO3/Nb:SrTiO3
cond-mat.str-el cond-mat.mtrl-sci
SrRuO3 (SRO), a conducting transition metal oxide, is commonly used for
engineering domains in BiFeO3. New oxide devices can be envisioned by
integrating SRO with an oxide semiconductor as Nb doped SrTiO3 (Nb:STO). Using
a three-terminal device configuration, we study vertical transport in a
SRO/Nb:STO device at the nanoscale and find local differences in transport,
that originate due to the high selectivity of SRO growth on the underlying
surface terminations in Nb:STO. This causes a change in the interface energy
band characteristics and is explained by the differences in the spatial
distribution of the interface-dipoles at the local Schottky interface.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-40981302.546 | CMOS-Compatible Nanowire Biosensors
cond-mat.mes-hall
In this chapter, silicon nanowires that are compatible with CMOS fabrication
processes have been described. It has been shown that these nanowires can be
functionalized by conjugating monoclonal antibodies to their surface in order
to build sensitive biochemical sensors. It has also been shown that by using
frequency-based signals, all the necessary components to interrogate these
nanowires can be built on low-cost CMOS processes.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-40991302.556 | Wormholes Threaded by Chiral Fields
gr-qc hep-th
We consider Lorentzian wormholes with a phantom field and chiral matter
fields. The chiral fields are described by the non-linear sigma model with or
without a Skyrme term. When the gravitational coupling of the chiral fields is
increased, the wormhole geometry changes. The single throat is replaced by a
double throat with a belly inbetween. For a maximal value of the coupling, the
radii of both throats reach zero. Then the interior part pinches off, leaving a
closed universe and two (asymptotically) flat spaces. A stability analysis
shows that all wormholes threaded by chiral fields inherit the instability of
the Ellis wormhole.
| arxiv topic:gr-qc hep-th |
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