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arxiv_dataset-46001309.2992 | Precision near-infrared radial velocity instrumentation I: Absorption
Gas Cells
astro-ph.IM astro-ph.SR
We have built and commissioned gas absorption cells for precision
spectroscopic radial velocity measurements in the near-infrared in the H and K
bands. We describe the construction and installation of three such cells filled
with 13CH4, 12CH3D, and 14NH3 for the CSHELL spectrograph at the NASA Infrared
Telescope Facility (IRTF). We have obtained their high-resolution laboratory
Fourier Transform spectra, which can have other practical uses. We summarize
the practical details involved in the construction of the three cells, and the
thermal and mechanical control. In all cases, the construction of the cells is
very affordable. We are carrying out a pilot survey with the 13CH4 methane gas
cell on the CSHELL spectrograph at the IRTF to detect exoplanets around low
mass and young stars. We discuss the current status of our survey, with the aim
of photon-noise limited radial velocity precision. For adequately bright
targets, we are able to probe a noise floor of 7 m/s with the gas cell with
CSHELL at cassegrain focus. Our results demonstrate the feasibility of using a
gas cell on the next generation of near-infrared spectrographs such as iSHELL
on IRTF, iGRINS, and an upgraded NIRSPEC at Keck.
| arxiv topic:astro-ph.IM astro-ph.SR |
arxiv_dataset-46011309.3092 | Study of interface phenomena in a topological-insulator/Mott-insulator
heterostructure
cond-mat.str-el
We theoretically investigate a two-dimensional heterostructure composed of a
topological insulator (TI) and a Mott insulator (MI), and clarify what kind of
electronic states can be realized at the interface. By using inhomogeneous
dynamical mean-field theory, we confirm that the topological edge state
penetrating into the MI region induces a heavy-fermion like mid-gap state. We
further elucidate the nature of the spatially-modulated quasi-particle weight
of the mid-gap state, and discuss the effects of local correlation in the TI
region. The optical conductivity and the Drude weight are also computed with
changing the electron tunneling near the interface.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-46021309.3192 | Light Sterile Neutrinos in Cosmology and Short-Baseline Oscillation
Experiments
hep-ph astro-ph.CO hep-ex
We analyze the most recent cosmological data, including Planck, taking into
account the possible existence of a sterile neutrino with a mass at the eV
scale indicated by short-baseline neutrino oscillations data in the 3+1
framework. We show that the contribution of local measurements of the Hubble
constant induces an increase of the value of the effective number of
relativistic degrees of freedom above the Standard Model value, giving an
indication in favor of the existence of sterile neutrinos and their
contribution to dark radiation. Furthermore, the measurements of the local
galaxy cluster mass distribution favor the existence of sterile neutrinos with
eV-scale masses, in agreement with short-baseline neutrino oscillations data.
In this case there is no tension between cosmological and short-baseline
neutrino oscillations data, but the contribution of the sterile neutrino to the
effective number of relativistic degrees of freedom is likely to be smaller
than one. Considering the Dodelson-Widrow and thermal models for the
statistical cosmological distribution of sterile neutrinos, we found that in
the Dodelson-Widrow model there is a slightly better compatibility between
cosmological and short-baseline neutrino oscillations data and the required
suppression of the production of sterile neutrinos in the early Universe is
slightly smaller.
| arxiv topic:hep-ph astro-ph.CO hep-ex |
arxiv_dataset-46031309.3292 | MacWilliams' Extension Theorem for Bi-Invariant Weights over Finite
Principal Ideal Rings
math.RA cs.IT math.IT
A finite ring R and a weight w on R satisfy the Extension Property if every
R-linear w-isometry between two R-linear codes in R^n extends to a monomial
transformation of R^n that preserves w. MacWilliams proved that finite fields
with the Hamming weight satisfy the Extension Property. It is known that finite
Frobenius rings with either the Hamming weight or the homogeneous weight
satisfy the Extension Property. Conversely, if a finite ring with the Hamming
or homogeneous weight satisfies the Extension Property, then the ring is
Frobenius.
This paper addresses the question of a characterization of all bi-invariant
weights on a finite ring that satisfy the Extension Property. Having solved
this question in previous papers for all direct products of finite chain rings
and for matrix rings, we have now arrived at a characterization of these
weights for finite principal ideal rings, which form a large subclass of the
finite Frobenius rings. We do not assume commutativity of the rings in
question.
| arxiv topic:math.RA cs.IT math.IT |
arxiv_dataset-46041309.3392 | Some aspects of shift-like automorphisms of C^k
math.DS
The goal of this article is two fold. First, using transcendental shift-like
automorphisms of C^k, k > 2 we construct two examples of non-degenerate entire
mappings with prescribed ranges. The first example exhibits an entire mapping
of C^k, k > 2 whose range avoids a given polydisc but contains the complement
of a slightly larger concentric polydisc. This generalizes a result of
Dixon-Esterle in C^2. The second example shows the existence of a
Fatou--Bieberbach domain in C^k,k > 2 that is constrained to lie in a
prescribed region. This is motivated by similar results of Buzzard and
Rosay-Rudin. In the second part we compute the order and type of entire
mappings that parametrize one dimensional unstable manifolds for shift-like
polynomial automorphisms and show how they can be used to prove a Yoccoz type
inequality for this class of automorphisms.
| arxiv topic:math.DS |
arxiv_dataset-46051309.3492 | Numerical multi-loop calculations with SecDec
hep-ph
The new version 2.1 of the program SecDec is described, which can be used for
the factorisation of poles and subsequent numerical evaluation of multi-loop
integrals, in particular massive two-loop integrals. The program is not
restricted to scalar master integrals; more general parametric integrals can
also be treated in an automated way.
| arxiv topic:hep-ph |
arxiv_dataset-46061309.3592 | Thermodynamic properties of a diluted triangular Ising antiferromagnet
in a field
cond-mat.stat-mech
Within the framework of the effective-field theory with correlations we
investigate effects of an external magnetic field and random site dilution on
basic thermodynamic quantities, such as the magnetization and the magnetic
susceptibility, of the geometrically frustrated triangular lattice Ising
antiferromagnet. Behavior of these quantities is presented in the
temperaturefield parameter space for selected mild degrees of dilution. It is
found that, besides the anomalies associated with phase transitions from the
ferrimagnetic to the paramagnetic state, in some regions of the parameter space
these functions display some more anomalies and peculiarities, as a result of
joint effects of the geometrical frustration, magnetic dilution, thermal
fluctuations and the applied magnetic field.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-46071309.3692 | Sufficient Conditions on the Optimality of Myopic Sensing in
Opportunistic Channel Access: A Unifying Framework
cs.IT math.IT
This paper considers a widely studied stochastic control problem arising from
opportunistic spectrum access (OSA) in a multi-channel system, with the goal of
providing a unifying analytical framework whereby a number of prior results may
be viewed as special cases. Specifically, we consider a single wireless
transceiver/user with access to $N$ channels, each modeled as an iid
discrete-time two-state Markov chain. In each time step the user is allowed to
sense $k\leq N$ channels, and subsequently use up to $m\leq k$ channels out of
those sensed to be available. Channel sensing is assumed to be perfect, and for
each channel use in each time step the user gets a unit reward. The user's
objective is to maximize its total discounted or average reward over a finite
or infinite horizon. This problem has previously been studied in various
special cases including $k=1$ and $m=k\leq N$, often cast as a restless bandit
problem, with optimality results derived for a myopic policy that seeks to
maximize the immediate one-step reward when the two-state Markov chain model is
positively correlated. In this paper we study the general problem with $1\leq
m\leq k\leq N$, and derive sufficient conditions under which the myopic policy
is optimal for the finite and infinite horizon reward criteria, respectively.
It is shown that these results reduce to those derived in prior studies under
the corresponding special cases, and thus may be viewed as a set of unifying
optimality conditions. Numerical examples are also presented to highlight how
and why an optimal policy may deviate from the otherwise-optimal myopic sensing
given additional exploration opportunities, i.e., when $m<k$.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-46081309.3792 | Exact Complexity: The Spectral Decomposition of Intrinsic Computation
cond-mat.stat-mech cs.IT math.IT nlin.CD nlin.CG
We give exact formulae for a wide family of complexity measures that capture
the organization of hidden nonlinear processes. The spectral decomposition of
operator-valued functions leads to closed-form expressions involving the full
eigenvalue spectrum of the mixed-state presentation of a process's
epsilon-machine causal-state dynamic. Measures include correlation functions,
power spectra, past-future mutual information, transient and synchronization
informations, and many others. As a result, a direct and complete analysis of
intrinsic computation is now available for the temporal organization of
finitary hidden Markov models and nonlinear dynamical systems with generating
partitions and for the spatial organization in one-dimensional systems,
including spin systems, cellular automata, and complex materials via chaotic
crystallography.
| arxiv topic:cond-mat.stat-mech cs.IT math.IT nlin.CD nlin.CG |
arxiv_dataset-46091309.3892 | Weighing matrices and spherical codes
math.CO
Mutually unbiased weighing matrices (MUWM) are closely related to an
antipodal spherical code with 4 angles. In the present paper, we clarify the
relationship between MUWM and the spherical sets, and give the complete
solution about the maximum size of a set of MUWM of weight 4 for any order.
Moreover we describe some natural generalization of a set of MUWM from the
viewpoint of spherical codes, and determine several maximum sizes of the
generalized sets. They include an affirmative answer of the problem of Best,
Kharaghani, and Ramp.
| arxiv topic:math.CO |
arxiv_dataset-46101309.3992 | ArDM: first results from underground commissioning
physics.ins-det
The Argon Dark Matter experiment is a ton-scale double phase argon Time
Projection Chamber designed for direct Dark Matter searches. It combines the
detection of scintillation light together with the ionisation charge in order
to discriminate the background (electron recoils) from the WIMP signals
(nuclear recoils). After a successful operation on surface at CERN, the
detector was recently installed in the underground Laboratorio Subterr\'aneo de
Canfranc, and the commissioning phase is ongoing. We describe the status of the
installation and present first results from data collected underground with the
detector filled with gas argon at room temperature.
| arxiv topic:physics.ins-det |
arxiv_dataset-46111309.4092 | WIMP-nucleon scattering with heavy WIMP effective theory
hep-ph astro-ph.CO hep-lat
The discovery of a Standard Model-like Higgs boson and the hitherto absence
of evidence for other new states may indicate that if WIMPs comprise
cosmological dark matter, they are heavy compared to electroweak scale
particles, $M \gg m_{W^\pm}, m_{Z^0}$. In this limit, the absolute cross
section for a WIMP of given electroweak quantum numbers to scatter from a
nucleon becomes computable in terms of Standard Model parameters. We develop
effective field theory techniques to analyze the heavy WIMP limit of
WIMP-nucleon scattering, and present the first complete calculation of the
leading spin-independent cross section in Standard Model extensions consisting
of one or two electroweak $SU(2)_W \times U(1)_Y$ multiplets.
| arxiv topic:hep-ph astro-ph.CO hep-lat |
arxiv_dataset-46121309.4192 | New lower bounds for the topological complexity of aspherical spaces
math.AT
We show that the topological complexity of an aspherical space $X$ is bounded
below by the cohomological dimension of the direct product $A\times B$,
whenever $A$ and $B$ are subgroups of $\pi_1(X)$ whose conjugates intersect
trivially. For instance, this assumption is satisfied whenever $A$ and $B$ are
complementary subgroups of $\pi_1(X)$. This gives computable lower bounds for
the topological complexity of many groups of interest (including semidirect
products, pure braid groups, certain link groups, and Higman's acyclic
four-generator group), which in some cases improve upon the standard lower
bounds in terms of zero-divisors cup-length. Our results illustrate an intimate
relationship between the topological complexity of an aspherical space and the
subgroup structure of its fundamental group.
| arxiv topic:math.AT |
arxiv_dataset-46131309.4292 | Continuous and discontinuous transitions in generalized p-spin glass
models
cond-mat.stat-mech cond-mat.dis-nn
We investigate the generalized p-spin models that contain arbitrary diagonal
operators U with no reflection symmetry. We derive general equations that give
an opportunity to uncover the behavior of the system near the glass transition
at different (continuous) p. The quadrupole glass with J=1 is considered as an
illustrating example. It is shown that the crossover from continuous to
discontinuous glass transition to one-step replica breaking solution takes
place at p=3.3 for this model. For p <2+\Delta p, where \Delta p= 0.5 is a
finite value, stable 1RSB-solution disappears. This behaviour is strongly
different from that of the p-spin Ising glass model.
| arxiv topic:cond-mat.stat-mech cond-mat.dis-nn |
arxiv_dataset-46141309.4392 | Regularized perturbative series for the ionization potential of atomic
ions
physics.atom-ph
We study $N$-electron atoms with nuclear charge $Z$. It is well known that,
in the cationic ($Z > N$) high-$Z$ region, the atom behaves as a weakly
interacting system. The anionic ($Z < N$) regime, on the other hand, is
characterized by an instability threshold at $Z_c \lesssim N-1$, below which
the atom spontaneously emits an electron. We construct a regularized
perturbative series (RPS) for the ionization potential of ions in an
isoelectronic sequence that exactly reproduces both, the large $Z$ and the $Z$
near $Z_c$ limits. The large-$Z$ expansion coefficients are analytically
computed from perturbation theory, whereas the slope of the energy curve at
$Z=N-1$ is computed from a kind of zero-range forces theory that uses as input
the electron affinity and the covalent radius of the neutral atom with $N-1$
electrons. Relativistic effects, at the level of first-order perturbation
theory, are considered. Our RPS formula is to be used in order to check the
consistency of the ionization potential values for atomic ions contained in the
NIST database.
| arxiv topic:physics.atom-ph |
arxiv_dataset-46151309.4492 | Observing supernova neutrino light curve in future dark matter detectors
astro-ph.HE astro-ph.SR hep-ph
The possibility of observing supernova (SN) neutrinos through the process of
coherent elastic neutrino-nucleus scattering (CENNS) in future ton scale
detectors designed primarily for direct detection of dark matter is
investigated. In particular, we focus on the possibility of distinguishing the
various phases of the SN neutrino emission. The neutrino emission rates from
the recent long term Basel/Darmstadt simulations are used to calculate the
expected event rates. The recent state-of-the-art SN simulations predict closer
fluxes among different neutrino flavors and lower average energies compared to
the earlier simulation models. We find that our estimated total event rates are
typically a factor of two lower than those predicted using older simulation
models. We further find that, with optimistic assumptions on the detector's
time resolution (~ 10 ms) and energy threshold (~ 0.1 keV), the neutrinos
associated with the accretion phase of the SN can in principle be demarcated
out with, for example, a 10-ton Xe detector, although distinguishing the
neutrinos associated with the neutronization burst phase of the explosion would
typically require several tens of ton detectors. We also comment on the
possibility of studying the properties of non-electron flavor neutrinos from
the CENNS of SN neutrinos.
| arxiv topic:astro-ph.HE astro-ph.SR hep-ph |
arxiv_dataset-46161309.4592 | The velocity operator in quantum mechanics in noncommutative space
math-ph math.MP
We tested in the framework of quantum mechanics the consequences of a
noncommutative (NC from now on) coordinates. We restricted ourselves to 3D
rotationally invariant NC configuration spaces with dynamics specified by the
Hamiltonian H = H(kin) + U, H(kin) is an analogue of kinetic energy and U =
U(r) denotes an arbitrary rotationally invariant potential. We introduced the
velocity operator by Heisenberg relation using the commutator of the coordinate
and the Hamiltonian operators. We found that the NC velocity operator possesses
various general, independent of potential, properties: 1) uncertainty relations
indicate an existence of a natural kinetic energy cut-off, 2) vanishing
commutator relations for velocity components, which is non-trivial in the NC
case, 3) modified relation between the velocity operator and H(kin) that
indicates the existence of maximal velocity and confirms the kinetic energy
cut-off, 4) All these results sum up in canonical (general, not depending on a
particular form of the central potential) commutation relations of the
Euclidean group E(4), 5) NC Heisenberg equation for the velocity operator,
relating acceleration to derivatives of the potential.
| arxiv topic:math-ph math.MP |
arxiv_dataset-46171309.4692 | An Analysis of the 'Blind Variation and Selective Retention' Theory of
Creativity
q-bio.NC q-bio.PE
Picasso's Guernica sketches continue to provide a fruitful testing ground for
examining and assessing the Blind Variation Selective Retention (BVSR) theory
of creativity. Nonmonotonicity--e.g. as indicated by a lack of similarity of
successive sketches--is not evidence of a selectionist process; Darwin's theory
explains adaptive change, not nonmonotonicity. Although the notion of blindness
originally implied randomness, it now encompasses phenomena that bias idea
generation, e.g. the influence of remote associations on sketch ideas. However,
for a selectionist framework is to be applicable, such biases must be
negligible, otherwise evolutionary change is attributed to those biases, not to
selection. The notion of 'variants' should not be applied to creativity;
without a mechanism of inheritance, there is no basis upon which to delineate,
for example, which sketch ideas are or are not variants of a given sketch idea.
The notion of selective retention is also problematic. Selection provides an
explanation when acquired change is not transmitted; it cannot apply to
Picasso's painting (or other creative acts) because his ideas acquired
modifications as he thought them through that were incorporated into paintings
and viewed by others. The generation of one sketch affects the criteria by
which the next is judged, so sequentially generated sketches cannot be treated
as members of a generation, and selected amongst. Although BVSR is
inappropriate as a theoretical framework for creativity, exploring to what
extent selectionism explains the generation of not just biological form but
masterpieces such as Picasso's Guernica is useful for gaining insight into
creativity.
| arxiv topic:q-bio.NC q-bio.PE |
arxiv_dataset-46181309.4792 | Feedback in a cavity QED system for control of quantum beats
quant-ph
Conditional measurements on the undriven mode of a two-mode cavity QED system
prepare a coherent superposition of ground states which generate quantum beats.
The continuous system drive induces decoherence through the phase interruptions
from Rayleigh scattering, which manifests as a decrease of the beat amplitude
and an increase of the frequency of oscillation. We report recent experiments
that implement a simple feedback mechanism to protect the quantum beat. We
continuously drive the system until a photon is detected, heralding the
presence of a coherent superposition. We then turn off the drive and let the
superposition evolve in the dark, protecting it against decoherence. At a later
time we reinstate the drive to measure the amplitude, phase, and frequency of
the beats. The amplitude can increase by more than fifty percent, while the
frequency is unchanged by the feedback.
| arxiv topic:quant-ph |
arxiv_dataset-46191309.4892 | Microscopic identification of dissipative modes in relativistic field
theories
hep-ph cond-mat.stat-mech
We present an argument to support the existence of dissipative modes in
relativistic field theories. In an O(N) $\varphi^4$ theory in spatial dimension
$d\le 3$, a relaxation constant $\Gamma$ of a two-point function in an infrared
region is shown to be finite within the two-particle irreducible (2PI)
framework at the next-leading order (NLO) of 1/N expansion. This immediately
implies that a slow dissipative mode with a dispersion $p_0\sim i\Gamma \p^2$
is microscopically identified in the two-point function. Contrary, NLO
calculation in the one-particle irreducible (1PI) framework fails to yield a
finite relaxation constant. Comparing the results in 1PI and 2PI frameworks,
one concludes that dissipation emerges from multiple scattering of a particle
with a heat bath, which is appropriately treated in the 2PI-NLO calculation
through the resummation of secular terms to improve long-time behavior of the
two-point function. Assuming that this slow dissipative mode survives at the
critical point, one can identify the dynamic critical exponent $z$ for the
two-point function as $z=2-\eta$. We also discuss possible improvement of the
result.
| arxiv topic:hep-ph cond-mat.stat-mech |
arxiv_dataset-46201309.4992 | Localization on round sphere revisited
hep-th
We consider supersymmetric gauge theories on round 3-sphere with a certain
background gauge field. The Lagrangians break the usual symmetry because the
background gauge field which we have turned on violates the isometry. In order
to maintain the supersymmetry, we choose unfamiliar charged Killing spinors as
N = 2 SUSY parameters. We perform localization calculous within this setup and
find the double sine function as we expected. We comment on more direct
relationship between theories on round sphere and squashed sphere via Weyl
transformation.
| arxiv topic:hep-th |
arxiv_dataset-46211309.5092 | Constraining Globular Cluster Formation Through Studies of Young Massive
Clusters: I. A lack of ongoing star formation within young clusters
astro-ph.CO
We present a survey of 130 Galactic and extragalactic young massive clusters
(YMCs, $10^4 < M/\msun < 10^8$, $10 < t/{\rm Myr} < 1000$) with integrated
spectroscopy or resolved stellar photometry (40 presented here and 90 from the
literature) and use the sample to search for evidence of ongoing star-formation
within the clusters. Such episodes of secondary (or continuous) star-formation
are predicted by models that attempt to explain the observed chemical and
photometric anomalies observed in globular clusters as being due to the
formation of a second stellar population within an existing first population.
Additionally, studies that have claimed extended star-formation histories
within LMC/SMC intermediate age clusters (1-2 Gyr), also imply that many young
massive clusters should show ongoing star-formation. Based on visual inspection
of the spectra and/or the colour-magnitude diagrams, we do not find evidence
for ongoing star-formation within any of the clusters, and use this to place
constraints on the above models. Models of continuous star-formation within
clusters, lasting for hundreds of Myr, are ruled out at high significance
(unless stellar IMF variations are invoked). Models for the (nearly
instantaneous) formation of a secondary population within an existing first
generation are not favoured, but are not formally discounted due to the finite
sampling of age/mass-space.
| arxiv topic:astro-ph.CO |
arxiv_dataset-46221309.5192 | A skew Gaussian decomposable graphical model
stat.ME math.ST stat.TH
This paper propose a novel decomposable graphical model to accommodate skew
Gaussian graphical models. We encode conditional independence structure among
the components of the multivariate closed skew normal random vector by means of
a decomposable graph and so that the pattern of zero off-diagonal elements in
the precision matrix corresponds to the missing edges of the given graph. We
present conditions that guarantee the propriety of the posterior distributions
under the standard noninformative priors for mean vector and precision matrix,
and a proper prior for skewness parameter. The identifiability of the
parameters is investigated by a simulation study. Finally, we apply our
methodology to two data sets.
| arxiv topic:stat.ME math.ST stat.TH |
arxiv_dataset-46231309.5292 | Speeding up Deciphering by Hypergraph Ordering
cs.CR math.CO
The "Gluing Algorithm" of Semaev [Des.\ Codes Cryptogr.\ 49 (2008), 47--60]
--- that finds all solutions of a sparse system of linear equations over the
Galois field $GF(q)$ --- has average running time $O(mq^{\max \left\vert
\cup_{1}^{k}X_{j}\right\vert -k}), $ where $m$ is the total number of
equations, and $\cup_{1}^{k}X_{j}$ is the set of all unknowns actively
occurring in the first $k$ equations. Our goal here is to minimize the exponent
of $q$ in the case where every equation contains at most three unknowns.
%Applying hypergraph-theoretic methods we prove The main result states that if
the total number $\left\vert \cup_{1}^{m}X_{j}\right\vert$ of unknowns is equal
to $m$, then the best achievable exponent is between $c_1m$ and $c_2m$ for some
positive constants $c_1$ and $c_2.$
| arxiv topic:cs.CR math.CO |
arxiv_dataset-46241309.5392 | Design optimization of mode-matched bulk-mode piezoelectric
micro-gyroscopes through modal analysis
physics.ins-det physics.optics
Bulk piezoelectric micro-gyroscope is a miniaturized inertial sensor that
uses a differential thickness-shear bulk mode of a PZT block as the drive mode
of the gyroscope. In the paper, a second differential thickness-extensional
mode is identified for the sense mode and mode-matching is proposed for the
first time by proper design of the device geomtries. Through finite element
modal analysis, the frequencies of drive mode and sense mode are obtained when
the length of the PZT block varies from 4.8mm to 5.6mm and the width of the PZT
block varies from 3.0mm to 4.0mm. Using a fitting method, the empirical
formulae with an excellent fit are induced to predict the influence of the
length and the width of the PZT block on the drive and sense mode frequencies.
Based on these empirical formulae, the mode-matching equations are introduced.
The analysis results show that for a given thickness of the PZT block, the
effect of the width on the drive mode frequency is prominant. Conversly, the
effect of length on the sense mode frequency is dominant. The resonance
frequencies, kinetic energy ratios, scale factors of gyroscope are compared to
evaluate the mode quality. The results show that the kinetic energy in y-axis
direction of the drive mode and the kinetic energy in z-axis direction of the
sense mode increase with the thickness of the PZT block, and consequently the
scale factor of the gyroscope increases. For a constant thickness of the PZT
block the scale factor will decrease as the length increases. Through design
optimization we present a 20 times improvement in the scale factor of the
mode-matched gyroscope. Given the thickness of PZT block, the length and the
width will be determined by the mode-matching equations mentioned. Generally,
the analysis suggests that the resolution of the gyroscope improves by
increasing the thickness PZT block.
| arxiv topic:physics.ins-det physics.optics |
arxiv_dataset-46251309.5492 | Photon flux and distance from the source: consequences for quantum
foundations and technologies
quant-ph
The paper explores the fundamental physical principles of quantum mechanics
(in fact, quantum field theory) which limit the bit rate for long distances.
Propagation of photons in optical fibers is modeled using methods of quantum
electrodynamics. We define photon "duration" as the standard deviation of the
photon arrival time; we find its asymptotics for long distances and then obtain
the main result of the paper: the linear dependence of photon duration on the
distance. This effect puts the limit to joint increasing of the photon flux and
the distance from the source and it has important consequences both for quantum
information technologies and quantum foundations. Once quantum communication
develops into a real technology, it would be appealing to the engineers to
increase both the photon flux and the distance. And here our "photon
flux/distance effect" has to be taken into account (at least if successively
emitted photons are considered as independent). This effect also has to be
taken into account in a loophole free test of Bell's type -- to close jointly
the detection and locality loopholes.
| arxiv topic:quant-ph |
arxiv_dataset-46261309.5592 | A nice lima\c{c}on-like spiral
math.DG
A lima\c{c}on-like curve, allowing 2{\pi}-transition with monotone curvature
between concentric curvature elements, is presented. The curve is 4th degree
algebraic, 4th degree rational, and shares other common features with Pascal's
lima\c{c}on.
| arxiv topic:math.DG |
arxiv_dataset-46271309.5692 | Axion as a Cold Dark Matter Candidate: Proof to Second order
astro-ph.CO gr-qc hep-th
We prove that the axion as a coherently oscillating scalar field acts as a
cold dark matter (CDM) to the second-order perturbations in all cosmological
scales including the super-horizon scale. The proof is made in the
axion-comoving gauge. For a canonical mass, the axion pressure term causes
deviation from the CDM only on scales smaller than the Solar System size.
Beyond such a small scale the equations of the axion fluid are the same as the
ones of the CDM based on the CDM-comoving gauge which are exactly identical to
the Newtonian equations to the second order. We also show that the axion fluid
does not generate the rotational (vector-type) perturbation even to the second
order. Thus, in the case of axion fluid, we have the relativistic/Newtonian
correspondence to the second order, even considering the rotational
perturbation. Our analysis is made in the presence of the cosmological
constant, and can be easily extended to the realistic situation including other
components of fluids and fields.
| arxiv topic:astro-ph.CO gr-qc hep-th |
arxiv_dataset-46281309.5792 | Lie algebroids, non-associative structures and non-geometric fluxes
hep-th
In the first part of this article, the geometry of Lie algebroids as well as
the Moyal-Weyl star product and some of its generalizations in open string
theory are reviewed. A brief introduction to T-duality and non-geometric fluxes
is given. Based on these foundations, more recent results are discussed in the
second part of the article. On the world-sheet level, we will analyse closed
string theory with flat background and constant H-flux. After an odd number of
T-dualities, correlation functions allow to extract a three-product having a
pattern similar to the Moyal-Weyl product. We then focus on the target space
and the local appearance of the various fluxes. An algebra based on vector
fields is proposed, whose structure functions are given by the fluxes.
Jacobi-identities for vector fields allow for the computation of
Bianchi-identities. Based on the latter, we give a proof for a special Courant
algebroid structure on the generalized tangent bundle, where the fluxes are
realized by the commutation relations of a basis of sections. As reviewed in
the first part of this work, in the description of non-geometric Q- and
R-fluxes, the B-field gets replaced by a bi-vector \beta, which is supposed to
serve as the dual object to B under T-duality. A natural question is about the
existence of a differential geometric framework allowing the construction of
actions manifestly invariant under coordinate- and gauge transformations, which
couple the \beta-field to gravity. It turns out that Lie algebroids are the
right language to answer this question positively. We conclude by giving an
outlook on future directions.
| arxiv topic:hep-th |
arxiv_dataset-46291309.5892 | Regularity for the supercritical fractional Laplacian with drift
math.AP math.PR
We consider the linear stationary equation defined by the fractional
Laplacian with drift. In the supercritical case, that is the case when the
dominant term is given by the drift instead of the diffusion component, we
prove local regularity of solutions in Sobolev spaces em- ploying tools from
the theory of pseudo-differential operators. The regularity of solutions in the
supercritical case is as expected in the subcritical case, when the diffusion
is at least as strong as the drift component, and the operator defined by the
fractional Laplacian with drift can be viewed as an elliptic operator, which is
not the case in the supercritical regime. We compute the leading singularity
for the Green's kernel in the supercritical range, which displays some unusual
behavior: it is more singular in the half plane into which the drift vector
points, than in the complementary half plane.
| arxiv topic:math.AP math.PR |
arxiv_dataset-46301309.5992 | Hydrodynamics of Euler incompressible fluid and the Fractional Quantum
Hall Effect
cond-mat.str-el cond-mat.mes-hall
We show that the Fractional Quantum Hall Effect can be phenomenologically
described as a special flow of a quantum incompressible Euler liquid. This flow
consists of a large number of vortices of the same chirality. In this approach
each vortex is identified with an electron while the fluid is neutral. We show
that the Laughlin wave function emerges as a stationary flow of the system of
vortices in quantum fluid dynamics. Subtle features of FQHE such as effects of
Lorentz shear stress, the spectral function, the Hall current in a modulated
electric fields, etc., naturally follow from the hydrodynamics approach. In the
paper we develop the hydrodynamics of the vortex liquid, and able consistently
quantize it. As a demonstration of the efficiency of the hydrodynamics we
discuss some new results for FQHE in a non-uniform magnetic field and a curved
space.
| arxiv topic:cond-mat.str-el cond-mat.mes-hall |
arxiv_dataset-46311309.6092 | Comparison of polarization switching in ferroelectric TGS and relaxor
SBN crystals
cond-mat.mtrl-sci
The comparative experimental analysis of polarization reversal kinetics in
conventional homogeneous triglycine sulfate ((NH_{2}CH_{2}COOH)_{3} \cdot
H_{2}SO_{4}; TGS) and relaxor strontium barium niobate
(Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}; SBN) crystals have been performed in a broad
range of measurement conditions. The experimental data have been collected from
microscopic observation of the domain structure, switching current and D-E
hysteresis loop registration. The hysteresis loop and dielectric spectra have a
strong link to the configuration of ferroelectric microdomains. The domain
structure dynamics was examined by the nematic liquid crystal (NLC) method.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-46321309.6192 | Entangling quantum and classical states of light
quant-ph
Entanglement between quantum and classical objects is of special interest in
the context of fundamental studies of quantum mechanics and potential
applications to quantum information processing. In quantum optics, single
photons are treated as light quanta while coherent states are considered the
most classical among all pure states. Recently, entanglement between a single
photon and a coherent state in a free-traveling field was identified to be a
useful resource for optical quantum information processing. However, it was
pointed out to be extremely difficult to generate such states since it requires
a clean cross-Kerr nonlinear interaction. Here, we devise and experimentally
demonstrate a scheme to generate such hybrid entanglement by implementing a
coherent superposition of two distinct quantum operations. The generated states
clearly show entanglement between the two different types of states. Our work
opens a way to generate hybrid entanglement of a larger size and to develop
efficient quantum information processing using such a new type of qubits.
| arxiv topic:quant-ph |
arxiv_dataset-46331309.6292 | A Fundamental System of Seminorms for $A(K)$
math.FA
Let $K\subset\R^d$ be compact and $A(K)$ the space of germs of real analytic
functions on $K$ with its natural (LF)-topology. This topology can be given by
$A(K)=\limind_{k\to+\infty} A_k$ where $A_k=\{(f_\alpha)_{\alpha\in\N_0^d}\in
C(K)^{\N_0^d}\,:\, \|f\|_k:=\sup_{x\in K} \frac{|f^{(\alpha)}(x)|}{\alpha!}
k^{-|\alpha|}< +\infty\}.$ Based on this description we give in the present
note an explicit fundamental system of seminorms for $A(K)$.
| arxiv topic:math.FA |
arxiv_dataset-46341309.6392 | Peeking Inside the Black Box: Visualizing Statistical Learning with
Plots of Individual Conditional Expectation
stat.AP
This article presents Individual Conditional Expectation (ICE) plots, a tool
for visualizing the model estimated by any supervised learning algorithm.
Classical partial dependence plots (PDPs) help visualize the average partial
relationship between the predicted response and one or more features. In the
presence of substantial interaction effects, the partial response relationship
can be heterogeneous. Thus, an average curve, such as the PDP, can obfuscate
the complexity of the modeled relationship. Accordingly, ICE plots refine the
partial dependence plot by graphing the functional relationship between the
predicted response and the feature for individual observations. Specifically,
ICE plots highlight the variation in the fitted values across the range of a
covariate, suggesting where and to what extent heterogeneities might exist. In
addition to providing a plotting suite for exploratory analysis, we include a
visual test for additive structure in the data generating model. Through
simulated examples and real data sets, we demonstrate how ICE plots can shed
light on estimated models in ways PDPs cannot. Procedures outlined are
available in the R package ICEbox.
| arxiv topic:stat.AP |
arxiv_dataset-46351309.6492 | Investigation of the Casimir interaction between two magnetic metals in
comparison with nonmagnetic test bodies
cond-mat.other quant-ph
We present the complete results for the dynamic experiment on measuring the
gradient of the Casimir force between magnetic (Ni-coated) surfaces of a plate
and a sphere. Special attention is paid to the description of some details of
the setup, its calibration, error analysis and background effects. Computations
are performed in the framework of the Lifshitz theory at nonzero temperature
with account of analytic corrections to the proximity force approximation and
of surface roughness using both the Drude and the plasma model approaches. The
theory of magnetic interaction between a sphere and a plate due to domain
structure of their surfaces is developed for both out-of-plane and in-plane
magnetizations in the absence and in the presence of spontaneous magnetization.
It is shown that in all cases the magnetic contribution to the measured force
gradients is much smaller than the total experimental error. The comparison
between experiment and theory is done using the rigorous statistical method. It
is shown that the theoretical approach taking into account dissipation of free
electrons is excluded by the data at a 95% confidence level. The approach
neglecting dissipation is confirmed by the data at more than 90% confidence
level. We prove that the results of experiments with Ni-Ni, Ni-Au and Au-Au
surfaces taken together cannot be reconciled with the approach including free
electrons dissipation by the introduction of any unaccounted background force,
either attractive or repulsive.
| arxiv topic:cond-mat.other quant-ph |
arxiv_dataset-46361309.6592 | The prompt-early afterglow connection in GRBs
astro-ph.HE
We study the observed correlations between the duration and luminosity of the
early afterglow plateau and the isotropic gamma-ray energy release during the
prompt phase. We discuss these correlations in the context of two scenarios for
the origin of the plateaus. In the first one the afterglow is made by the
forward shock and the plateau results from variations of the microphysics
parameters while in the second one the early afterglow is made by a long-lived
reverse shock propagating in a low Lorentz factor tail of the ejecta.
| arxiv topic:astro-ph.HE |
arxiv_dataset-46371309.6692 | Signal transduction and directional sensing in eukaryotes
q-bio.CB
Control of the cytoskeleton and mechanical contacts with the extracellular
environment are essential component of motility in eukaryotic cells. In the
absence of signals, cells continuously rebuild the cytoskeleton and
periodically extend pseudopods or other protrusions at random membrane
locations. Extracellular signals bias the direction of movement by biasing the
extension of protrusions, but this involves another layer of biochemical
networks for signal detection, transduction, and control of the rebuilding of
the cytoskeleton. Here we develop a model for the latter processes that centers
on a Ras-based module that adapts to constant extracellular signals and
controls the downstream PI3K-PIP3-based module responsible for amplifying a
spatial gradient of the signal. The resulting spatial gradient can lead to
polarization, which enables cells to move in the preferred direction (up
gradient for attractants and down-gradient for repellents). We show that the
model can replicate many of the observed characteristics of the responses to
cAMP stimulation for Dictyostelium, and analyze how cell geometry and signaling
interact to produce the observed localization of some of the key components of
the amplification module. We show how polarization can emerge without
directional cues, and how it interacts with directional signals and leads to
directional persistence. Since other cells such as neutrophils use similar
pathways, the model is a generic one for a large class of eukaryotic cells.
| arxiv topic:q-bio.CB |
arxiv_dataset-46381309.6792 | The long helical jet of the Lighthouse nebula, IGR J11014-6103
astro-ph.HE
Jets from rotation-powered pulsars have so far only been observed in systems
moving subsonically trough their ambient medium and/or embedded in their
progenitor supernova remnant (SNR). Supersonic runaway pulsars are also
expected to produce jets, but they have not been confirmed so far. We
investigated the nature of the jet-like structure associated to the INTEGRAL
source IGR J11014-6103 (the "Lighthouse nebula"). The source is a neutron star
escaping its parent SNR MSH 11-61A supersonically at a velocity exceeding 1000
km/s. We observed the Lighthouse nebula and its jet-like X-ray structure
through dedicated high spatial resolution observations in X-rays (Chandra) and
radio band (ATCA). Our results show that the feature is a true pulsar's jet. It
extends highly collimated over >11pc, displays a clear precession-like
modulation, and propagates nearly perpendicular to the system direction of
motion, implying that the neutron star's spin axis in IGR J11014-6103 is almost
perpendicular to the direction of the kick received during the supernova
explosion. Our findings suggest that jets are common to rotation-powered
pulsars, and demonstrate that supernovae can impart high kick velocities to
misaligned spinning neutron stars, possibly through distinct, exotic,
core-collapse mechanisms.
| arxiv topic:astro-ph.HE |
arxiv_dataset-46391309.6892 | Comment on the Theory of the Stretching Experiments of RNA in Water
cond-mat.soft
Is is argued that the stretching experiments done on RNA in water can be
described as a reversible process by Classical Thermodynamics.
| arxiv topic:cond-mat.soft |
arxiv_dataset-46401309.6992 | Energy flux measurement from the dissipated energy in capillary wave
turbulence
physics.flu-dyn cond-mat.other nlin.CD physics.class-ph
We study experimentally the influence of dissipation on stationary capillary
wave turbulence on the surface of a fluid by changing its viscosity. We observe
that the frequency power law scaling of the capillary spectrum departs
significantly from its theoretical value when the dissipation is increased. The
energy dissipated by capillary waves is also measured and found to increase
nonlinearly with the mean power injected within the fluid. Here, we propose an
experimental estimation of the energy flux at every scale of the capillary
cascade. The latter is found to be non constant through the scales. For fluids
of low enough viscosity, we found that both capillary spectrum scalings with
the frequency and the newly defined mean energy flux are in good agreement with
wave turbulence theory. The Kolmogorov-Zakharov constant is then experimentally
estimated and compared to its theoretical value.
| arxiv topic:physics.flu-dyn cond-mat.other nlin.CD physics.class-ph |
arxiv_dataset-46411309.7092 | Generating Anisotropic Collapse and Expansion Solutions of Einstein's
Equations
gr-qc
Analytic gravitational collapse and expansion solutions with anisotropic
pressure are generated. Metric functions are found by requiring zero heat flow
scalar. It emerges that a single function generates the anisotropic solutions.
Each generating function contains an arbitrary function of time which can be
chosen to fit various astrophysical time profiles. Two examples are provided: a
bounded collapse metric and an expanding cosmological solution
| arxiv topic:gr-qc |
arxiv_dataset-46421309.7192 | A Torelli type problem for logarithmic bundles over projective varieties
math.AG
We investigate the logarithmic bundles associated to arrangements of
hypersurfaces with a fixed degree in a smooth projective variety. We then
specialize to the case when the variety is a quadric hypersurface and a
multiprojective space to prove a Torelli type theorem in some cases.
| arxiv topic:math.AG |
arxiv_dataset-46431309.7292 | Mapping continuous potentials to discrete forms
cond-mat.soft
The optimal conversion of a continuous inter-particle potential to a discrete
equivalent is considered here. Existing and novel algorithms are evaluated to
determine the best technique for creating accurate discrete forms using the
minimum number of discontinuities. This allows the event-driven molecular
dynamics technique to be efficiently applied to the wide range of continuous
force models available in the literature, and facilitates a direct comparison
of event-driven and time-driven molecular dynamics. The performance of the
proposed conversion techniques are evaluated through application to the
Lennard-Jones model. A surprising linear dependence of the computational cost
on the number of discontinuities is found, allowing accuracy to be traded for
speed in a controlled manner. Excellent agreement is found for static and
dynamic properties using a relatively low number of discontinuities. For the
Lennard-Jones potential, the optimized discrete form outperforms the original
continuous form at gas densities but is significantly slower at higher
densities.
| arxiv topic:cond-mat.soft |
arxiv_dataset-46441309.7392 | The International Pulsar Timing Array
astro-ph.IM
The International Pulsar Timing Array (IPTA) is an organisation whose raison
d'etre is to facilitate collaboration between the three main existing PTAs (the
EPTA in Europe, NANOGrav in North America and the PPTA in Australia) in order
to realise the benefits of combined PTA data sets in reaching the goals of PTA
projects. Currently, shared data sets for 39 pulsars are available for
IPTA-based projects. Operation of the IPTA is administered by a Steering
Committee consisting of six members, two from each PTA, plus the immediate past
Chair in a non-voting capacity. A Constitution and several Agreements define
the framework for the collaboration. Web pages provide information both to
members of participating PTAs and to the general public. With support from an
NSF PIRE grant, the IPTA facilitates the organisation of annual Student
Workshops and Science Meetings. These are very valuable both in training new
students and in communicating current results from IPTA-based research.
| arxiv topic:astro-ph.IM |
arxiv_dataset-46451309.7492 | Solar-energy conversion and light emission in an atomic monolayer p-n
diode
cond-mat.mes-hall
Two-dimensional (2D) atomic crystals, such as graphene and atomically thin
transition metal dichalcogenides (TMDCs), are currently receiving a lot of
attention. They are crystalline, and thus of high material quality, even so,
they can be produced in large areas and are bendable, thus providing
opportunities for novel applications. Here, we report a truly 2D p-n junction
diode, based on an electrostatically doped tungsten diselenide (WSe2)
monolayer. As p-n diodes are the basic building block in a wide variety of
optoelectronic devices, our demonstration constitutes an important advance
towards 2D optoelectronics. We present applications as (i) photovoltaic solar
cell, (ii) photodiode, and (iii) light emitting diode. Light power conversion
and electroluminescence efficiencies are ca. 0.5 % and 0.1 %, respectively.
Given the recent advances in large-scale production of 2D crystals, we expect
them to profoundly impact future developments in solar, lighting, and display
technologies.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-46461309.7592 | On the reducibility of Schlesinger isomonodromic families
math.CA
We obtain some sufficient conditions for reducibility of a Schlesinger
isomonodromic family with the (block) upper-triangular monodromy to the same
(block) upper-triangular form via a constant gauge transformation. We also
obtain integral representations of hypergeometric type for entries of
upper-triangular solutions of the Schlesinger equation.
| arxiv topic:math.CA |
arxiv_dataset-46471309.7692 | A Model of Colonic Crypts using SBML Spatial
cs.CE q-bio.MN
The Spatial Processes package enables an explicit definition of a spatial
environment on top of the normal dynamic modeling SBML capabilities. The
possibility of an explicit representation of spatial dynamics increases the
representation power of SBML. In this work we used those new SBML features to
define an extensive model of colonic crypts composed of the main cellular types
(from stem cells to fully differentiated cells), alongside their spatial
dynamics.
| arxiv topic:cs.CE q-bio.MN |
arxiv_dataset-46481309.7792 | Astrochemistry: Synthesis and Modelling
astro-ph.GA
We discuss models that astrochemists have developed to study the chemical
composition of the interstellar medium. These models aim at computing the
evolution of the chemical composition of a mixture of gas and dust under as-
trophysical conditions. These conditions, as well as the geometry and the
physical dynamics, have to be adapted to the objects being studied because
different classes of objects have very different characteristics (temperatures,
densities, UV radia- tion fields, geometry, history etc); e.g., proto-planetary
disks do not have the same characteristics as protostellar envelopes. Chemical
models are being improved continually thanks to comparisons with observations
but also thanks to laboratory and theoretical work in which the individual
processes are studied.
| arxiv topic:astro-ph.GA |
arxiv_dataset-46491309.7892 | Observation of a topological 3D Dirac semimetal phase in high-mobility
Cd3As2
cond-mat.mes-hall cond-mat.str-el
Experimental identification of three-dimensional (3D) Dirac semimetals in
solid state systems is critical for realizing exotic topological phenomena and
quantum transport such as the Weyl phases, high temperature linear quantum
magnetoresistance and topological magnetic phases. Using high resolution
angle-resolved photoemission spectroscopy, we performed systematic electronic
structure studies on well-known compound Cd3As2. For the first time, we observe
a highly linear bulk Dirac cone located at the Brillouin zone center projected
onto the (001) surface which is consistent with a 3D Dirac semimetal phase in
Cd3As2. Remarkably, an unusually high Dirac Fermion velocity up to 10.2
\textrm{\AA}{\cdot}$eV (1.5 \times 10^{6} ms^-1) is seen in samples where the
mobility far exceeds 40,000 cm^2/V.s suggesting that Cd3As2 can be a promising
candidate as a hypercone analog of graphene in many device-applications which
can also incorporate topological quantum phenomena in a large gap setting. Our
experimental identification of this novel topological 3D Dirac semimetal phase,
distinct from a 3D topological insulator phase discovered previously, paves the
way for exploring higher dimensional relativistic physics in bulk transport and
for realizing novel Fermionic matter such as a Fermi arc nodal metal.
| arxiv topic:cond-mat.mes-hall cond-mat.str-el |
arxiv_dataset-46501309.7992 | Bound entangled states with extremal properties
quant-ph
Following recent work of Beigi and Shor, we investigate PPT states that are
"heavily entangled." We first exploit volumetric methods to show that in a
randomly chosen direction, there are PPT states whose distance in trace norm
from separable states is (asymptotically) at least 1/4. We then provide
explicit examples of PPT states which are nearly as far from separable ones as
possible. To obtain a distance of 2-{\epsilon} from the separable states, we
need a dimension of 2^{poly(\log(1/\epsilon))}, as opposed to
2^{poly(1/\epsilon)} given by the construction of Beigi and Shor. We do so by
exploiting the so called {\it private states}, introduced earlier in the
context of quantum cryptography. We also provide a lower bound for the distance
between private states and PPT states and investigate the distance between pure
states and the set of PPT states.
| arxiv topic:quant-ph |
arxiv_dataset-46511310.0097 | Analysis of Amoeba Active Contours
cs.CV
Subject of this paper is the theoretical analysis of structure-adaptive
median filter algorithms that approximate curvature-based PDEs for image
filtering and segmentation. These so-called morphological amoeba filters are
based on a concept introduced by Lerallut et al. They achieve similar results
as the well-known geodesic active contour and self-snakes PDEs. In the present
work, the PDE approximated by amoeba active contours is derived for a general
geometric situation and general amoeba metric. This PDE is structurally similar
but not identical to the geodesic active contour equation. It reproduces the
previous PDE approximation results for amoeba median filters as special cases.
Furthermore, modifications of the basic amoeba active contour algorithm are
analysed that are related to the morphological force terms frequently used with
geodesic active contours. Experiments demonstrate the basic behaviour of amoeba
active contours and its similarity to geodesic active contours.
| arxiv topic:cs.CV |
arxiv_dataset-46521310.0197 | Compact quantum gates on electron-spin qubits assisted by diamond
nitrogen-vacancy centers inside cavities
quant-ph
Constructing compact quantum circuits for universal quantum gates on
solid-state systems is crucial for quantum computing. We present some compact
quantum circuits for a deterministic solid-state quantum computing, including
the CNOT, Toffoli, and Fredkin gates on the diamond nitrogen-vacancy centers
confined inside cavities, achieved by some input-output processes of a single
photon. Our quantum circuits for these universal quantum gates are simple and
economic. Moreover, additional electron qubits are not employed, but only a
single-photon medium. These gates have a long coherent time. We discuss the
feasibility of these universal solid-state quantum gates, concluding that they
are feasible with current technology.
| arxiv topic:quant-ph |
arxiv_dataset-46531310.0297 | Sampling generalized cat states with linear optics is probably hard
quant-ph
Boson-sampling has been presented as a simplified model for linear optical
quantum computing. In the boson-sampling model, Fock states are passed through
a linear optics network and sampled via number-resolved photodetection. It has
been shown that this sampling problem likely cannot be efficiently classically
simulated. This raises the question as to whether there are other quantum
states of light for which the equivalent sampling problem is also
computationally hard. We present evidence, without using a full complexity
proof, that a very broad class of quantum states of light --- arbitrary
superpositions of two or more coherent states --- when evolved via passive
linear optics and sampled with number-resolved photodetection, likely
implements a classically hard sampling problem.
| arxiv topic:quant-ph |
arxiv_dataset-46541310.0397 | Project 8: Using Radio-Frequency Techniques to Measure Neutrino Mass
physics.ins-det hep-ex nucl-ex
The Project 8 experiment aims to measure the neutrino mass using tritium beta
decays. Beta-decay electron energies will be measured with a novel technique:
as the electrons travel in a uniform magnetic field their cyclotron radiation
will be detected. The frequency of each electron's cyclotron radiation is
inversely proportional to its total relativistic energy; therefore, by
observing the cyclotron radiation we can make a precise measurement of the
electron energies. The advantages of this technique include scalability,
excellent energy resolution, and low backgrounds. The collaboration is using a
prototype experiment to study the feasibility of the technique with a
$^{83m}$Kr source. Demonstrating the ability to see the 17.8 keV and 30.2 keV
conversion electrons from $^{83m}$Kr will show that it may be possible to
measure tritium beta-decay electron energies ($Q \approx 18.6$ keV) with their
cyclotron radiation. Progress on the prototype, analysis and signal-extraction
techniques, and an estimate of the potential future of the experiment will be
discussed.
| arxiv topic:physics.ins-det hep-ex nucl-ex |
arxiv_dataset-46551310.0497 | Potentially Singular Solutions of the 3D Incompressible Euler Equations
physics.flu-dyn math.NA
Whether the 3D incompressible Euler equations can develop a singularity in
finite time from smooth initial data is one of the most challenging problems in
mathematical fluid dynamics. This work attempts to provide an affirmative
answer to this long-standing open question from a numerical point of view, by
presenting a class of potentially singular solutions to the Euler equations
computed in axisymmetric geometries. The solutions satisfy a periodic boundary
condition along the axial direction and no-flow boundary condition on the solid
wall. The equations are discretized in space using a hybrid 6th-order Galerkin
and 6th-order finite difference method, on specially designed adaptive (moving)
meshes that are dynamically adjusted to the evolving solutions. With a maximum
effective resolution of over $(3 \times 10^{12})^{2}$ near the point of the
singularity, we are able to advance the solution up to $\tau_{2} = 0.003505$
and predict a singularity time of $t_{s} \approx 0.0035056$, while achieving a
\emph{pointwise} relative error of $O(10^{-4})$ in the vorticity vector
$\omega$ and observing a $(3 \times 10^{8})$-fold increase in the maximum
vorticity $\|\omega\|_{\infty}$. The numerical data are checked against all
major blowup (non-blowup) criteria, including Beale-Kato-Majda,
Constantin-Fefferman-Majda, and Deng-Hou-Yu, to confirm the validity of the
singularity. A local analysis near the point of the singularity also suggests
the existence of a self-similar blowup in the meridian plane.
| arxiv topic:physics.flu-dyn math.NA |
arxiv_dataset-46561310.0597 | The basis property of generalized Jacobian elliptic functions
math.CA math.AP
The Jacobian elliptic functions are generalized to functions including the
generalized trigonometric functions. The paper deals with the basis property of
the sequence of generalized Jacobian elliptic functions in any Lebesgue space.
In particular, it is shown that the sequence of the classical Jacobian elliptic
functions is a basis in any Lebesgue space if the modulus $k$ satisfies $0 \le
k \le 0.99$.
| arxiv topic:math.CA math.AP |
arxiv_dataset-46571310.0697 | Possible consistent extra time dimensions in the early universe
physics.gen-ph
Gravity cannot be quantized unless the quantized theory is cast on a manifold
whose concomitant number of physical space dimensions and number of physical
time dimensions correspond to physical reality, and not simply to the
perception of reality. At present, the accepted number of physical time
dimensions is dictated more by folklore than by science. In this paper we
discuss a model of the early universe in which the number of physical time
dimensions is four, and formulate Theorem[\ref{tj}], which underlies an
explanation of why the extra time dimensions do not source unphysical effects.
In this paper we describe a new model of gravitational inflation that is
driven by dark energy and "mediated" by a real massless scalar inflaton field
$\varphi$ whose potential is identically equal to zero. The coupled Einstein
gravitational and inflaton field equations are formulated on an
eight-dimensional spacetime manifold of \textbf{four space} dimensions and
\textbf{four time} dimensions. We find explicit solutions to these field
equations that exhibit temporal exponential \textbf{deflation of three of the
four time dimensions}, and then study the dynamics of a massive complex scalar
field $\psi$ that propagates on the background ground state Einstein
gravitational field to determine whether its quantum fluctuations $\delta \psi$
are stable or unstable. We compute explicit approximate solutions to the
$\delta \psi$ field equations that are \textbf{stable}, meaning that the
quantum fluctuations $\delta \psi$ of the field $\psi$ do not grow
exponentially with time. \textbf{Instabilities} driven by the momenta
associated to the three extra time dimensions do not appear in the physical
solutions of the field equations of this model.
| arxiv topic:physics.gen-ph |
arxiv_dataset-46581310.0797 | The sedimentation of flexible filaments: Trajectories, particle clouds
and a buckling instability
physics.flu-dyn cond-mat.soft
In this fluid dynamics video we explore an array of different possible
dynamics for a flexible filament sedimenting in a viscous fluid. The
time-dependent shapes and trajectories of the filament are determined
analytically and numerically by balancing viscous, elastic and gravitational
forces in a slender-body theory for zero-Reynolds number flows. The dynamics
are characterized by a single dimensionless elasto-gravitation number. The
video shows the process of filament relaxation and reorientation, the formation
of particle clouds, and finally a buckling instability.
| arxiv topic:physics.flu-dyn cond-mat.soft |
arxiv_dataset-46591310.0897 | A New Generalization of Fermat's Last Theorem
math.NT
In this paper, we consider some hybrid Diophantine equations of addition and
multiplication. We first improve a result on new Hilbert-Waring problem. Then
we consider the equation \begin{equation}
\begin{cases}
A+B=C
ABC=D^n
\end{cases} \end{equation} where $A,B,C,D,n \in\ZZ_{+}$ and $n\geq3$, which
may be regarded as a generalization of Fermat's equation $x^n+y^n=z^n$. When
$\gcd(A,B,C)=1$, $(1)$ is equivalent to Fermat's equation, which means it has
no positive integer solutions. We discuss several cases for $\gcd(A,B,C)=p^k$
where $p$ is an odd prime. In particular, for $k=1$ we prove that $(1)$ has no
nonzero integer solutions when $n=3$ and we conjecture that it is also true for
any prime $n>3$. Finally, we consider equation $(1)$ in quadratic fields
$\mathbb{Q}(\sqrt{t})$ for $n=3$.
| arxiv topic:math.NT |
arxiv_dataset-46601310.0997 | Spectroscopic factor of the 1+, 25Al(p,g)26Si resonance at Ex=5.68 MeV
astro-ph.SR nucl-th
Nuclear shell model predictions for the proton spectroscopic factor of the
1+, Ex = 5.68 MeV level in 26Si are about fifty times smaller than the value
suggested by the measured (a,3He) cross section for the Ex = 5.69 MeV mirror
level in 26Mg, assuming purely single-particle transfer. Given that the 5.69
MeV level has been very weakly, if it all, populated in previous studies of the
simpler 25Mg(d,p) reaction, it is unclear if the (a,3He) result is a true
single-particle spectroscopic factor. If we assume the (a,3He) result, the
thermonuclear rate of the 25Al(p,g)26Si reaction would increase by factors of 6
- 50 over stellar temperatures of T = 0.05 - 0.2 GK. We examine the
implications of this enhanced rate for model predictions of nucleosynthesis in
classical nova explosions.
| arxiv topic:astro-ph.SR nucl-th |
arxiv_dataset-46611310.1097 | Comment on "Nonexistence of the final first integral in the
Zipoy-Voorhees space-time"
gr-qc astro-ph.SR
The accuracy of the numerical findings of Lukes-Gerakopoulos PRD 86, 044013
(2012), regarding the existence of additional first integrals in the
Zipoy-Voorhees space-time, was recently questioned by Maciejewski et al. PRD
88, 064003 (2013). In this comment, it is shown that the discrepancy between
the results of Lukes-Gerakopoulos (2012) and Maciejewski et al. (2013) is not
due to issues related to numerical accuracy, as claimed in Maciejewski et al
(2013), but due to different choice of coordinates used in Maciejewski et
al.(2013).
| arxiv topic:gr-qc astro-ph.SR |
arxiv_dataset-46621310.1197 | Second-Order Asymptotics for the Gaussian MAC with Degraded Message Sets
cs.IT math.IT
This paper studies the second-order asymptotics of the Gaussian
multiple-access channel with degraded message sets. For a fixed average error
probability $\varepsilon \in (0,1)$ and an arbitrary point on the boundary of
the capacity region, we characterize the speed of convergence of rate pairs
that converge to that boundary point for codes that have asymptotic error
probability no larger than $\varepsilon$. As a stepping stone to this local
notion of second-order asymptotics, we study a global notion, and establish
relationships between the two. We provide a numerical example to illustrate how
the angle of approach to a boundary point affects the second-order coding rate.
This is the first conclusive characterization of the second-order asymptotics
of a network information theory problem in which the capacity region is not a
polygon.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-46631310.1297 | Spectral Clustering for Divide-and-Conquer Graph Matching
stat.ML math.OC stat.CO
We present a parallelized bijective graph matching algorithm that leverages
seeds and is designed to match very large graphs. Our algorithm combines
spectral graph embedding with existing state-of-the-art seeded graph matching
procedures. We justify our approach by proving that modestly correlated, large
stochastic block model random graphs are correctly matched utilizing very few
seeds through our divide-and-conquer procedure. We also demonstrate the
effectiveness of our approach in matching very large graphs in simulated and
real data examples, showing up to a factor of 8 improvement in runtime with
minimal sacrifice in accuracy.
| arxiv topic:stat.ML math.OC stat.CO |
arxiv_dataset-46641310.1397 | The role of interference in unraveling the ZZ-couplings of the newly
discovered boson at the LHC
hep-ph hep-ex
We present a general procedure for measuring the tensor structure of the
coupling of the scalar Higgs-like boson recently discovered at the LHC to two Z
bosons, including the effects of interference among different operators. To
motivate our concern with this interference, we explore the parameter space of
the couplings in the effective theory describing these interactions and
illustrate the effects of interference on the differential dilepton mass
distributions. Kinematic discriminants for performing coupling measurements
that utilize the effects of interference are developed and described. We
present projections for the sensitivity of coupling measurements that use these
discriminants in future LHC operation in a variety of physics scenarios.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-46651310.1497 | Magnetospheric Accretions and the Inner Winds of Classical T Tauri Stars
astro-ph.SR
Recent spectropolarimetric observations suggest that young low-mass stars
such as classical T Tauri stars (CTTSs) possess relatively strong (~kG)
magnetic field. This supports a scenario in which the final accretion onto the
stellar surface proceeds through a magnetosphere, and the winds are formed in
magnetohydrodynamics (MHD) processes. We examine recent numerical simulations
of magnetospheric accretions via an inclined dipole and a complex magnetic
fields. The difference between a stable accretion regime, in which accretion
occurs in ordered funnel streams, and an unstable regime, in which gas
penetrates through the magnetosphere in several unstable streams due to the
magnetic Rayleigh-Taylor instability, will be discussed. We describe how MHD
simulation results can be used in separate radiative transfer (RT) models to
predict observable quantiles such as line profiles and light curves. The
plausibility of the accretion flows and outflows predicted by MHD simulations
(via RT models) can be tested against observations. We also address the issue
of outflows/winds that arise from the innermost part of CTTSs. First, we
discuss the line formations in a simple disk wind and a stellar wind models. We
then discuss the formation of the conically shaped magnetically driven outflow
that arises from the disk-magnetosphere boundary when the magnetosphere is
compressed into an X-type configuration.
| arxiv topic:astro-ph.SR |
arxiv_dataset-46661310.1597 | Cross-lingual Pseudo-Projected Expectation Regularization for Weakly
Supervised Learning
cs.CL cs.AI
We consider a multilingual weakly supervised learning scenario where
knowledge from annotated corpora in a resource-rich language is transferred via
bitext to guide the learning in other languages. Past approaches project labels
across bitext and use them as features or gold labels for training. We propose
a new method that projects model expectations rather than labels, which
facilities transfer of model uncertainty across language boundaries. We encode
expectations as constraints and train a discriminative CRF model using
Generalized Expectation Criteria (Mann and McCallum, 2010). Evaluated on
standard Chinese-English and German-English NER datasets, our method
demonstrates F1 scores of 64% and 60% when no labeled data is used. Attaining
the same accuracy with supervised CRFs requires 12k and 1.5k labeled sentences.
Furthermore, when combined with labeled examples, our method yields significant
improvements over state-of-the-art supervised methods, achieving best reported
numbers to date on Chinese OntoNotes and German CoNLL-03 datasets.
| arxiv topic:cs.CL cs.AI |
arxiv_dataset-46671310.1697 | Quantum Monte Carlo Simulations for Stacked Spin Ladder Systems
Containing Low Concentrations of Non-Magnetic Impurities; Application to the
Low Temperature Broadening of NMR-Spectra in SrCu2O3
cond-mat.str-el physics.comp-ph
We present a Quantum Monte Carlo study for Heisenberg spin-1/2 two leg ladder
systems doped with non magnetic impurities. The simulations are applied to the
doped spin ladder compound SrCu2O3 doped with Zn, where a large broadening of
the 65Cu NMR lines has been observed in experiment at low temperatures but far
above the Neel temperature. We find that interladder-couplings with a sizeable
coupling in stacking direction are required to describe the line broadening,
which can not be explained by considering a single ladder only. Around a single
impurity, spin correlations cause an exponentially decaying antiferromagnetic
local magnetization in a magnetic field. We develop an effective model for the
local magnetization of systems with many randomly distributed impurities, with
few parameters which can be extracted out of QMC calculations with a single
impurity. The broadening arises from a drag effect, where the magnetization
around an impurity works as an effective field for spins on the neighboring
ladders, causing a non-exponentially decaying magnetization cloud around the
impurity. Our results show that even for impurity concentrations as small as x
= 0.001 and x = 0.0025, the broadening effect is large, in good quantitative
agreement with experiment. We also develop a simple model for the effective
interaction of two impurity spins.
| arxiv topic:cond-mat.str-el physics.comp-ph |
arxiv_dataset-46681310.1797 | Quark Sector of the QCD Groundstate in Coulomb Gauge
hep-ph hep-th
The variational approach to Yang-Mills theory in Coulomb gauge is extended to
full QCD. For the quark sector we use a trial wave functional, which goes
beyond the previously used BCS-type state and which explicitly contains the
coupling of the quarks to transverse gluons. This quark wave functional
contains two variational kernels: One is related to the quark condensate and
occurs already in the BCS-type states. The other represents the form factor of
the coupling of the quarks to the transverse gluons. Minimization of the energy
density with respect to these kernels results in two coupled integral (gap)
equations. These equations are solved numerically using the confining part of
the non-Abelian color Coulomb potential and the lattice static gluon propagator
as input. With the additional coupling of quarks to transverse gluons included
the low energy chiral properties increase substantially towards their
phenomenological values. We obtain a reasonable description of the chiral
condensate, which for a vanishing current quark mass is obtained in the range
of 190-235 MeV. The coupling of the quarks to the transverse gluons enhances
the constituent quark mass by about 60% in comparison to the pure BCS ansatz.
| arxiv topic:hep-ph hep-th |
arxiv_dataset-46691310.1897 | Circuit QED - Lecture Notes
quant-ph cond-mat.supr-con
The new and rapidly growing field of circuit QED offers extremely exciting
prospects for learning about and exercising intimate control over quantum
systems, providing flexible, engineerable design and strong nonlinearities and
interactions in systems consisting of microwave radiation fields and fixed
artificial "atoms". These notes aim to provide a non-expert introduction to the
field of circuit QED, to give a basic appreciation of the promise and
challenges of the field, along with a number of key concepts that will
hopefully be useful for the reader who is new to the field and beginning to
explore the research literature. They were written as a pedagogical text
designed to complement a course delivered to third-year undergraduate students.
After a introductory section which discusses why studying circuit QED might
be worthwhile and interesting, I introduce the basic theory tools from quantum
optics and quantum information which are needed to understand the key elements
of circuit QED. I also provide a brief overview of superconductivity, focussing
on the concepts which are most relevant to operation in the regimes of interest
in circuit QED. I then describe the three main types of superconducting qubits,
and finally give a basic introduction to decoherence and mixture and how they
relate to quantum behaviour in electronic circuits.
| arxiv topic:quant-ph cond-mat.supr-con |
arxiv_dataset-46701310.1997 | Ferroelectric field effect of the bulk heterojunction in polymer solar
cells
cond-mat.mtrl-sci
A ferroelectric field effect in the bulk heterojunction was found when an
external electric field (EEF) was applied on the active layer of polymer solar
cells (PSCs) during the annealing process of the active layer spin-coated with
poly (3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM).
For one direction field, the short circuit current density of PSCs was improved
from 7.2 to 8.0 mA/cm2, the power conversion efficiency increased from 2.4 to
2.8%, and the incident photon-to-current conversion efficiency increased from
42 to 49% corresponding to the different EEF magnitude. For an opposite
direction field, the applied EEF brought a minus effect on the performance
mentioned above. EEF treatment can orientate molecular ordering of the polymer,
and change the morphology of the active layer. The authors suggest a
explanation that the ferroelectric field has been built in the active layer,
and therefore it plays a key role in PSCs system. A needle-like surface
morphology of the active film was also discussed.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-46711310.2097 | Interface dipoles of organic molecules on Ag(111) in hybrid
density-functional theory
cond-mat.mtrl-sci
We investigate the molecular acceptors 3,4,9,10-perylene-tetracarboxylic acid
dianhydride (PTCDA), 2,3,5,6-tetra uoro-7,7,8,8-tetracyanoquinodimethane
(F4TCNQ), and 4,5,9,10-pyrenetetraone (PYTON) on Ag(111) using
densityfunctional theory. For two groups of the HSE(\alpha, \omega) family of
exchange-correlation functionals (\omega = 0 and \omega = 0.2\AA) we study the
isolated components as well as the combined systems as a function of the amount
of exact-exchange (\alpha). We find that hybrid functionals favour electron
transfer to the adsorbate. Comparing to experimental work-function data, we
report for (\alpha) ca. 0.25 a notable but small improvement over (semi)local
functionals for the interface dipole. Although Kohn-Sham eigenvalues are only
approximate representations of ionization energies, incidentally, at this value
also the density of states agrees well with the photoelectron spectra. However,
increasing (\alpha) to values for which the energy of the lowest unoccupied
molecular orbital matches the experimental electron affinity in the gas phase
worsens both the interface dipole and the density of states. Our results imply
that semi-local DFT calculations may often be adequate for conjugated organic
molecules on metal surfaces and that the much more computationally demanding
hybrid functionals yield only small improvements.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-46721310.2197 | Why should we keep measuring zenital dependence of muon flux? Results
obtained at Campinas (SP) BR
astro-ph.IM hep-ex physics.ins-det
The zenital dependence of muon flux which reaches the earth's surface is well
known as proportional to cos^n(\theta). Generally, for practical purposes and
simplicity in calculations, n is taken as 2. However, compilations of
measurements show dependence on the geographical location of the experiments as
well as the muons energy range. Since analytical solutions appear to be
increasingly less necessary because of the higher accessibility to low cost
computational power, accurate and precise determination of the value of the
exponent n, under different conditions, can be useful in the necessary
calculations to estimate signals and backgrounds, either for terrestrial and
underground experiments. In this work we discuss a method for measuring n using
a simple muon telescope and the results obtained for measurements taken at
Campinas (SP), Brazil. After validation of the method, we intend to extend the
measurements for different geographic locations due to the simplicity of the
method, and thus collect more values of n that currently exist in compilations
of general data on cosmic rays.
| arxiv topic:astro-ph.IM hep-ex physics.ins-det |
arxiv_dataset-46731310.2297 | Producing type Iax supernovae from a specific class of helium-ignited WD
explosions?
astro-ph.SR
It has recently been proposed that one sub-class of type Ia supernovae (SNe
Ia) is sufficiently both distinct and common to be classified separately from
the bulk of SNe Ia, with a suggested class name of "type Iax supernovae" (SNe
Iax), after SN 2002cx. However, their progenitors are still uncertain. We study
whether the population properties of this class might be understood if the
events originate from a subset of sub-Chandrasekhar mass explosions. In this
potential progenitor population, a carbon--oxygen white dwarf (CO WD)
accumulates a helium layer from a non-degenerate helium star; ignition of that
helium layer then leads to ignition of the CO WD. We incorporated detailed
binary evolution calculations for the progenitor systems into a binary
population synthesis model to obtain rates and delay times for such events. The
predicted Galactic event rate of these explosions is ~1.5\times10^{-3}{yr}^{-1}
according to our standard model, in good agreement with the measured rates of
SNe Iax. In addition, predicted delay times are ~70Myr-800Myr, consistent with
the fact that most of SNe Iax have been discovered in late-type galaxies. If
the explosions are assumed to be double-detonations -- following current model
expectations -- then based on the CO WD masses at explosion we also estimate
the distribution of resulting SN brightness (-13 \gtrsim M_{bol} \gtrsim
-19mag), which can reproduce the empirical diversity of SNe Iax. We speculate
on why binaries with non-degenerate donor stars might lead to SNe Iax if
similar systems with degenerate donors do not. We suggest that the high mass of
the helium layer necessary for ignition at the lower accretion rates typically
delivered from non-degenerate donors might be necessary to produce SN
2002cx-like characteristics, perhaps even by changing the nature of the CO
ignition.
| arxiv topic:astro-ph.SR |
arxiv_dataset-46741310.2397 | On Minty's theorem in the Heisenberg group
math.CA math.FA
In this paper we extend some classical results of Convex Analysis to the
sub-Riemannian setting of the Heisenberg group. In particular, we provide a
horizontal version of Minty's theorem concerning maximal H-monotone operators
defined in the Heisenberg group with values in the first layer of its Lie
algebra.
| arxiv topic:math.CA math.FA |
arxiv_dataset-46751310.2497 | The symplectic properties of the PGL(n,C)-gluing equations
math.GT hep-th
In a previous article we studied PGL(n,C)-representations of a 3-manifold via
a generalization of Thurston's gluing equations. Neumann has proved some
symplectic properties of Thurston's gluing equations that play an important
role in recent developments of exact and perturbative Chern-Simons theory. In
this paper, we prove the symplectic properties of the PGL(n,C)-gluing equations
for all ideal triangulations of compact oriented 3-manifolds.
| arxiv topic:math.GT hep-th |
arxiv_dataset-46761310.2597 | CXOGBS~J173620.2--293338: A Candidate Symbiotic X-ray Binary Associated
with a Bulge Carbon Star
astro-ph.HE astro-ph.SR
The Galactic Bulge Survey is a wide but shallow X-ray survey of regions above
and below the Plane in the Galactic Bulge. It was performed using the Chandra
X-ray Observatory's ACIS camera. The survey is primarily designed to find and
classify low luminosity X-ray binaries. The combination of the X-ray depth of
the survey and the accessibility of optical and infrared counterparts makes
this survey ideally suited to identification of new symbiotic X-ray binaries in
the Bulge. We consider the specific case of the X-ray source CXOGBS
J173620.2-293338. It is coincident to within 1 arcsec with a very red star,
showing a carbon star spectrum and irregular variability in the Optical
Gravitational Lensing Experiment data. We classify the star as a late C-R type
carbon star based on its spectral features, photometric properties, and
variability characteristics, although a low-luminosity C-N type cannot be ruled
out. The brightness of the star implies it is located in the Bulge, and its
photometric properties overall are consistent with the Bulge carbon star
population. Given the rarity of carbon stars in the Bulge, we estimate the
probability of such a close chance alignment of any Galactic Bulge Survey
source with a carbon star to be <1e-3 suggesting that this is likely to be a
real match. If the X-ray source is indeed associated with the carbon star, then
the X-ray luminosity is around 9e32 erg/s. Its characteristics are consistent
with a low luminosity symbiotic X-ray binary, or possibly a low accretion rate
white dwarf symbiotic.
| arxiv topic:astro-ph.HE astro-ph.SR |
arxiv_dataset-46771310.2697 | Low-energy electric dipole response of Sn isotopes
nucl-th nucl-ex
We study the low-energy dipole (LED) strength distribution along the Sn
isotopic chain in both the isoscalar (IS) and the isovector (IV, or E1)
electric channels, to provide testable predictions and guidance for new
experiments with stable targets and radioactive beams. We use the
self-consistent Quasi-particle Random-Phase Approximation (QRPA) with
finite-range interactions and mainly the Gogny D1S force. We analyze also the
performance of a realistic two-body interaction supplemented by a
phenomenological three-body contact term. We find that from N=50 and up to the
N=82 shell closure (132Sn) the lowest-energy part of the IS-LED spectrum is
dominated by a collective transition whose properties vary smoothly with
neutron number and which cannot be interpreted as a neutron-skin oscillation.
For the neutron-rich species this state contributes to the E1 strength below
particle threshold, but much more E1 strength is carried by other, weak but
numerous transitions around or above threshold. We find that strong structural
changes in the spectrum take effect beyond N=82, namely increased LED strength
and lower excitation energies. Our results with the Gogny interaction are
compatible with existing data. On this basis we predict that a) the summed IS
strength below particle threshold shall be of the same order of magnitude for
N=50-82, b) the summed E1 strength up to approximately 12 MeV shall be similar
for N=50-82 MeV, while c) the summed E1 strength below threshold shall be of
the same order of magnitude for N ~ 64 - 82 and much weaker for the lighter,
more-symmetric isotopes. We point out a general agreement of our results with
other non-relativistic studies, the absence of a collective IS mode in some of
those studies, and a possibly radical disagreement with relativistic models.
| arxiv topic:nucl-th nucl-ex |
arxiv_dataset-46781310.2797 | Lemma Mining over HOL Light
cs.AI cs.DL cs.LG cs.LO
Large formal mathematical libraries consist of millions of atomic inference
steps that give rise to a corresponding number of proved statements (lemmas).
Analogously to the informal mathematical practice, only a tiny fraction of such
statements is named and re-used in later proofs by formal mathematicians. In
this work, we suggest and implement criteria defining the estimated usefulness
of the HOL Light lemmas for proving further theorems. We use these criteria to
mine the large inference graph of all lemmas in the core HOL Light library,
adding thousands of the best lemmas to the pool of named statements that can be
re-used in later proofs. The usefulness of the new lemmas is then evaluated by
comparing the performance of automated proving of the core HOL Light theorems
with and without such added lemmas.
| arxiv topic:cs.AI cs.DL cs.LG cs.LO |
arxiv_dataset-46791310.2897 | A Classification of the Veldkamp Lines of the Near Hexagon L_3 times
GQ(2, 2)
math.CO math-ph math.AG math.MP
Using a standard technique sometimes (inaccurately) known as Burnside's
Lemma, it is shown that the Veldkamp space of the near hexagon L_3 times GQ(2,
2) features 156 different types of lines. We also give an explicit description
of each type of a line by listing the types of the three geometric hyperplanes
it consists of and describing the properties of its core set, that is the
subset of points of L_3 times GQ(2, 2) shared by the three geometric
hyperplanes in question.
| arxiv topic:math.CO math-ph math.AG math.MP |
arxiv_dataset-46801310.2997 | Bandits with Switching Costs: T^{2/3} Regret
cs.LG math.PR
We study the adversarial multi-armed bandit problem in a setting where the
player incurs a unit cost each time he switches actions. We prove that the
player's $T$-round minimax regret in this setting is
$\widetilde{\Theta}(T^{2/3})$, thereby closing a fundamental gap in our
understanding of learning with bandit feedback. In the corresponding
full-information version of the problem, the minimax regret is known to grow at
a much slower rate of $\Theta(\sqrt{T})$. The difference between these two
rates provides the \emph{first} indication that learning with bandit feedback
can be significantly harder than learning with full-information feedback
(previous results only showed a different dependence on the number of actions,
but not on $T$.)
In addition to characterizing the inherent difficulty of the multi-armed
bandit problem with switching costs, our results also resolve several other
open problems in online learning. One direct implication is that learning with
bandit feedback against bounded-memory adaptive adversaries has a minimax
regret of $\widetilde{\Theta}(T^{2/3})$. Another implication is that the
minimax regret of online learning in adversarial Markov decision processes
(MDPs) is $\widetilde{\Theta}(T^{2/3})$. The key to all of our results is a new
randomized construction of a multi-scale random walk, which is of independent
interest and likely to prove useful in additional settings.
| arxiv topic:cs.LG math.PR |
arxiv_dataset-46811310.3097 | A code space for a generalized IFS
math.GT math.DS
We study the concept of a code (or shift) space for a generalized iterated
function system (GIFS in short). We prove that relations between GIFSs and
their code spaces are analogous to the case of classical IFSs. As an
application, we consider the problem of connectedness of attractors of GIFSs.
Many of our results are strengthenings of the ones proved recently by Mihail,
Miculescu and Secelean, but some are completely new.
| arxiv topic:math.GT math.DS |
arxiv_dataset-46821310.3197 | Routes for breaching and protecting genetic privacy
q-bio.GN cs.CR stat.AP
We are entering the era of ubiquitous genetic information for research,
clinical care, and personal curiosity. Sharing these datasets is vital for
rapid progress in understanding the genetic basis of human diseases. However,
one growing concern is the ability to protect the genetic privacy of the data
originators. Here, we technically map threats to genetic privacy and discuss
potential mitigation strategies for privacy-preserving dissemination of genetic
data.
| arxiv topic:q-bio.GN cs.CR stat.AP |
arxiv_dataset-46831310.3297 | Bertini for Macaulay2
math.AG cs.MS
Numerical algebraic geometry is the field of computational mathematics
concerning the numerical solution of polynomial systems of equations. Bertini,
a popular software package for computational applications of this field,
includes implementations of a variety of algorithms based on polynomial
homotopy continuation. The Macaulay2 package Bertini.m2 provides an interface
to Bertini, making it possible to access the core run modes of Bertini in
Macaulay2. With these run modes, users can find approximate solutions to
zero-dimensional systems and positive-dimensional systems, test numerically
whether a point lies on a variety, sample numerically from a variety, and
perform parameter homotopy runs.
| arxiv topic:math.AG cs.MS |
arxiv_dataset-46841310.3397 | Regression techniques for Portfolio Optimisation using MOSEK
q-fin.PM math.OC
Regression is widely used by practioners across many disciplines. We
reformulate the underlying optimisation problem as a second-order conic program
providing the flexibility often needed in applications. Using examples from
portfolio management and quantitative trading we solve regression problems with
and without constraints. Several Python code fragments are given. The code and
data are available online at http://www.github.com/tschm/MosekRegression.
| arxiv topic:q-fin.PM math.OC |
arxiv_dataset-46851310.3497 | Herschel observations: contraints on dust attenuation and star formation
histories at high redshift
astro-ph.CO
SPICA is one of the key projects for the future. Not only its instrument
suite will open up a discovery window but they will also allow to physically
understand some of the phenomena that we still do not understand in the
high-redshift universe. Using new homogeneous luminosity functions (LFs) in the
Far-Ultraviolet (FUV) from VVDS and in the Far-Infrared (FIR) from Herschel/PEP
and Herschel/HerMES, we studied the evolution of the dust attenuation with
redshift. With this information, we are able to estimate the redshift evolution
of the total (FUV + FIR) star formation rate density (SFRD_TOT). Our main
conclusions are that: 1) the dust attenuation A_FUV is found to increase from z
= 0 to $z \sim 1.2 and then starts to decrease until our last data point at z =
3.6; 2) the estimated SFRD confirms published results to z \sim 2. At z > 2, we
observe either a plateau or a small increase up to z \sim 3 and then a likely
decrease up to z = 3.6; 3) the peak of A_FUV is delayed with respect to the
plateau of SFRD_TOT but the origin of this delay is not understood yet, and
SPICA instruments will provide clues to move further in the physical
understanding of this delay but also on the detection and redshift measurements
of galaxies at higher redshifts. This work is further detailed in Burgarella et
al. (2013).
| arxiv topic:astro-ph.CO |
arxiv_dataset-46861310.3597 | Heavy vs. light flavor energy loss within a partonic transport model
hep-ph nucl-th
The full space-time evolution of gluons, light and heavy quarks in
ultra-relativistic heavy-ion collisions is studied within the partonic
transport model Boltzmann Approach to MultiParton Scatterings (BAMPS). We
discuss for light and heavy quarks the elastic and radiative energy loss with a
running coupling. Radiative processes, in particular, are implemented through
an improved version of the Gunion-Bertsch matrix element, which is derived from
comparisons to the exact result, explicitly taking finite heavy quark masses
into account. Subsequently, we present results with and without radiative
processes and compare them to experimental data at LHC. A focus is put on the
nuclear modification factor of charged hadrons and D mesons.
| arxiv topic:hep-ph nucl-th |
arxiv_dataset-46871310.3697 | Variance Adjusted Actor Critic Algorithms
stat.ML cs.LG cs.SY
We present an actor-critic framework for MDPs where the objective is the
variance-adjusted expected return. Our critic uses linear function
approximation, and we extend the concept of compatible features to the
variance-adjusted setting. We present an episodic actor-critic algorithm and
show that it converges almost surely to a locally optimal point of the
objective function.
| arxiv topic:stat.ML cs.LG cs.SY |
arxiv_dataset-46881310.3797 | High temperature expansion for dynamical correlation functions in the
infinite-U Hubbard Model
cond-mat.str-el
We develop a diagrammatic approach for calculating the high temperature
expansion of dynamic correlation functions, such as the electron Green's
function and the time-dependent density-density and spin-spin correlation
functions, for the infinite-U Hubbard Model with any number of spin species.
The formalism relies on the use of restricted lattice sums, in which distinct
vertices of the diagram represent distinct sites on the lattice. We derive a
new formula for the restricted lattice sum of a disconnected diagram consisting
of several connected components, and use it to prove the linked cluster theorem
with respect to "generalized connected diagrams", formed by overlapping the
original connected components on the lattice. This enables us to express all
quantities as a sum over these generalized connected diagrams. We compute the
Green's function to 4th order in \beta t for the case of m spin species on a
d-dimensional hypercube by hand. We take the m\to\infty limit, enabling us to
obtain expressions for the Dyson-Mori self-energy to 4th order in \beta t for
the case of an infinite number of spin species. This may have connections to
slave boson techniques used for the study of this model. Our approach is
computationally more efficient than any used previously for the calculation of
the high temperature expansion of dynamic correlation functions, and high order
results for both the Green's function and the time-dependent density-density
and spin-spin correlation functions shall be presented in a separate paper
[25].
| arxiv topic:cond-mat.str-el |
arxiv_dataset-46891310.3897 | Y Chromosomes of 40% Chinese Are Descendants of Three Neolithic
Super-grandfathers
q-bio.PE q-bio.GN
Demographic change of human populations is one of the central questions for
delving into the past of human beings. To identify major population expansions
related to male lineages, we sequenced 78 East Asian Y chromosomes at 3.9 Mbp
of the non-recombining region (NRY), discovered >4,000 new SNPs, and identified
many new clades. The relative divergence dates can be estimated much more
precisely using molecular clock. We found that all the Paleolithic divergences
were binary; however, three strong star-like Neolithic expansions at ~6 kya
(thousand years ago) (assuming a constant substitution rate of 1e-9/bp/year)
indicates that ~40% of modern Chinese are patrilineal descendants of only three
super-grandfathers at that time. This observation suggests that the main
patrilineal expansion in China occurred in the Neolithic Era and might be
related to the development of agriculture.
| arxiv topic:q-bio.PE q-bio.GN |
arxiv_dataset-46901310.3997 | Non-thermal radio emission from O-type stars. V. 9 Sgr
astro-ph.SR astro-ph.HE
The colliding winds in a massive binary system generate synchrotron emission
due to a fraction of electrons that have been accelerated to relativistic
speeds around the shocks in the colliding-wind region. We studied the radio
light curve of 9 Sgr = HD 164794, a massive O-type binary with a 9.1-yr period.
We investigated whether the radio emission varies consistently with orbital
phase and we determined some parameters of the colliding-wind region. We
reduced a large set of archive data from the Very Large Array (VLA) to
determine the radio light curve of 9 Sgr at 2, 3.6, 6 and 20 cm. We also
constructed a simple model that solves the radiative transfer in the
colliding-wind region and both stellar winds. The 2-cm radio flux shows clear
phase-locked variability with the orbit. The behaviour at other wavelengths is
less clear, mainly due to a lack of observations centred on 9 Sgr around
periastron passage. The high fluxes and nearly flat spectral shape of the radio
emission show that synchrotron radiation dominates the radio light curve at all
orbital phases. The model provides a good fit to the 2-cm observations,
allowing us to estimate that the brightness temperature of the synchrotron
radiation emitted in the colliding-wind region at 2 cm is at least 4 x 10^8 K.
The simple model used here already allows us to derive important information
about the colliding-wind region. We propose that 9 Sgr is a good candidate for
more detailed modelling, as the colliding-wind region remains adiabatic during
the whole orbit thus simplifying the hydrodynamics.
| arxiv topic:astro-ph.SR astro-ph.HE |
arxiv_dataset-46911310.4097 | A Clash-of-Symmetries Mechanism from Intersecting Domain-Wall Branes
hep-ph
We present a new Clash-of-Symmetries mechanism in the context of an
intersecting domain-wall brane model in 5+1-dimensional Minkowskian spacetime
recently proposed by the authors. This new application of the Dvali-Shifman
idea is designed for localizing gauge fields on a domain-wall intersection and
we employ it by adding a gauge group $G$ and giving the scalar fields which
form lump-like profiles gauge charges. These fields in turn break $G$ to two
different subgroups $H_{1}$ and $H_{2}$ on each domain wall, and the gauge
fields of these subgroups are taken to be localized to the respective walls by
the confinement dynamics of $G$. There is then a further breaking on the
domain-wall intersection to $H_{1}\cap{}H_{2}$ and gauge fields of this overlap
group can then be localized to the intersection if they belong inside
non-Abelian subgroups of both $H_{1}$ and $H_{2}$ which are spontaneously
broken on the intersection and confining in the 4+1D bulks of the respective
domain-wall branes. This mechanism has some similarities to the
Clash-of-Symmetries mechanism on a single domain wall except that in this case
$H_{1}$ and $H_{2}$ need not be isomorphic. We then give some interesting
examples of the mechanism in an SU(7) gauge theory, several of which result in
the localization of the Standard Model gauge group.
| arxiv topic:hep-ph |
arxiv_dataset-46921310.4197 | Maximum likelihood geometry in the presence of data zeros
math.AG
Given a statistical model, the maximum likelihood degree is the number of
complex solutions to the likelihood equations for generic data. We consider
discrete algebraic statistical models and study the solutions to the likelihood
equations when the data contain zeros and are no longer generic. Focusing on
sampling and model zeros, we show that, in these cases, the solutions to the
likelihood equations are contained in a previously studied variety, the
likelihood correspondence. The number of these solutions give a lower bound on
the ML degree, and the problem of finding critical points to the likelihood
function can be partitioned into smaller and computationally easier problems
involving sampling and model zeros. We use this technique to compute a lower
bound on the ML degree for $2 \times 2 \times 2 \times 2$ tensors of border
rank $\leq 2$ and $3 \times n$ tables of rank $\leq 2$ for $n=11, 12, 13, 14$,
the first four values of $n$ for which the ML degree was previously unknown.
| arxiv topic:math.AG |
arxiv_dataset-46931310.4297 | Enhanced two-photon absorption using true thermal light
quant-ph physics.optics
Two-photon excited fluorescence (TPEF) is a standard technique in modern
microscopy but still affected by photo-damage of the probe. It was proposed
that TPEF can be enhanced by using entangled photons, but has proven to be
challenging. Recently it was shown that some features of entangled photons can
be mimicked with thermal light, which finds application in ghost imaging,
sub-wavelength lithography and metrology. Here, we utilize true thermal light
from a super-luminescence diode to demonstrate enhanced TPEF compared to
coherent light using two common fluorophores and luminescent quantum dots. We
find that the two-photon absorption rate is directly proportional to the
measured degree of second-order coherence, as predicted by theory. Our results
show that photon bunching can be exploited in two-photon microscopy with the
photon statistic providing a new degree of freedom.
| arxiv topic:quant-ph physics.optics |
arxiv_dataset-46941310.4397 | Stable One-Dimensional Integral Representations of One-Loop N-Point
Functions in the General Massive Case: I - Three Point Functions
hep-ph
In this article we provide representations for the one-loop three point
functions in 4 and 6 dimensions in the general case with complex masses. The
latter are part of the GOLEM library used for the computation of one-loop
multileg amplitudes. These representations are one-dimensional integrals
designed to be free of instabilites induced by inverse powers of Gram
determinants, therefore suitable for stable numerical implementations.
| arxiv topic:hep-ph |
arxiv_dataset-46951310.4497 | The [alpha/Fe] ratios of very metal-poor stars within the IGIMF theory
astro-ph.GA astro-ph.CO
The aim of this paper is to quantify the amplitude of the predicted plateau
in [alpha/Fe] ratios associated with the most metal-poor stars of a galaxy. We
assume that the initial mass function in galaxies is steeper if the star
formation rate (SFR) is low -- as per the integrated galactic initial mass
function (IGIMF) theory. A variant of the theory, in which the IGIMF depends
upon the metallicity of the parent galaxy, is also considered. The IGIMF theory
predicts low [alpha/Fe] plateaus in dwarf galaxies, characterised by small
SFRs. The [alpha/Fe] plateau is up to 0.7dex lower than the corresponding
plateau of the Milky Way. For a universal IMF one should expect instead that
the [alpha/Fe] plateau is the same for all the galaxies, irrespective of their
masses or SFRs. Assuming a strong dependence of the IMF on the metallicity of
the parent galaxy, dwarf galaxies can show values of the [alpha/Fe] plateau
similar to those of the Milky Way, and almost independent on the SFR. The
[Mg/Fe] ratios of the most metal-poor stars in dwarf galaxies satellites of the
Milky Way can be reproduced either if we consider metallicity-dependent IMFs or
if the early SFRs of these galaxies were larger than we presently think.
Present and future observations of dwarf galaxies can help disentangle between
these different IGIMF formulations.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-46961310.4597 | Pseudogap and singlet formation in cuprate and organic superconductors
cond-mat.str-el cond-mat.mtrl-sci
The pseudogap phase occurring in cuprate and organic superconductors is
analyzed based on the dynamical cluster approximation (DCA) approach to the
Hubbard model. A cluster embedded in a self-consistent bath is studied. With
increasing Coulomb repulsion, U, the antinodal point [k=(pi,0)] displays a
gradual suppression of spectral density of states around the Fermi energy which
is not observed at the nodal point [k=(pi/2,pi/2)]. The opening of the
antinodal pseudogap is related to the internal structure of the cluster and the
much weaker bath-cluster couplings at the antinodal than nodal point. The role
played by internal cluster correlations is elucidated from a simple four-level
model. For small U, the cluster levels form Kondo singlets with their baths
leading to a peak in the spectral density. As U is increased a localized state
is formed localizing the electrons in the cluster. If this cluster localized
state is non-degenerate, the Kondo effect is destroyed and a pseudogap opens up
in the spectra at the anti-nodal point. The pseudogap can be understood in
terms of destructive interference between different paths for electrons hopping
between the cluster and the bath. However, electrons at the nodal points remain
in Kondo states up to larger U since they are more strongly coupled to the
bath. The strong correlation between the (pi,0) and (0,pi) cluster levels in
the localized state leads to a large correlation energy gain which is important
for localizing electrons and opening up a pseudogap. Such scenario is in
contrast with two independent Mott transitions found in two-band systems with
different bandwidths in which the localized cluster electron does not correlate
strongly with any other cluster electron for intermediate U. The important
intracluster sector correlations are associated with the resonating valence
bond (RVB) character of the cluster.
| arxiv topic:cond-mat.str-el cond-mat.mtrl-sci |
arxiv_dataset-46971310.4697 | Existence and regularity of maximal metrics for the first Laplace
eigenvalue on surfaces
math.AP
We investigate in this paper the existence of a metric which maximizes the
first eigenvalue of the Laplacian on Riemannian surfaces. We first prove that,
in a given conformal class, there always exists such a maximizing metric which
is smooth except at a finite set of conical singularities. This result is
similar to the beautiful result concerning Steklov eigenvalues recently
obtained by Fraser and Schoen. Then we get existence results among all metrics
on surfaces of a given genus, leading to the existence of minimal isometric
immersions of smooth compact Riemannian manifold $(M,g)$ of dimension 2 into
some $k$-sphere by first eigenfunctions. At last, we also answer a conjecture
of Friedlander and Nadirashvili which asserts that the supremum of the first
eigenvalue of the Laplacian on a conformal class can be taken as close as we
want of its value on the sphere on any orientable surface.
| arxiv topic:math.AP |
arxiv_dataset-46981310.4797 | Homotopy automorphisms of R-module bundles, and the K-theory of string
topology
math.AT
Let $R$ be a ring spectrum and $ E\to X$ an $R$-module bundle of rank $n$.
Our main result is to identify the homotopy type of the group-like monoid of
homotopy automorphisms of this bundle, $hAut^R(E)$. This will generalize the
result regarding $R$-line bundles previously proven by the authors. The main
application is the calculation of the homotopy type of $BGL_n(End ((L))$ where
$L \to X$ is any $R$-line bundle, and $End (L)$ is the ring spectrum of
endomorphisms. In the case when such a bundle is the fiberwise suspension
spectrum of a principal bundle over a manifold, $G \to P \to M$, this leads to
a description of the $K$-theory of the string topology spectrum in terms of the
mapping space from $M$ to $BGL (\Sigma^\infty (G_+))$.
| arxiv topic:math.AT |
arxiv_dataset-46991310.4897 | Nonlinear Integrated Microwave Photonics
physics.optics
Harnessing nonlinear optical effects in a photonic chip scale has been proven
useful for a number of key applications in optical communications. Microwave
photonics can also benefit from the adoption of such a technology, creating a
new concept of nonlinear integrated microwave photonics. Here, we discuss the
potential of on-chip nonlinear processing towards the creation of robust and
multifunctional microwave photonic (MWP) processors. We also highlight key
recent results in the field, including frequency agile MWP filters and
ultra-wideband signal generators.
| arxiv topic:physics.optics |
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