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arxiv_dataset-61001503.07286 | Feasibility study of online tuning of the luminosity in a circular
collider with the robust conjugate direction search method
physics.acc-ph
The robust conjugate direction search (RCDS) method has high tolerance to
noise in beam experiments. It has been demonstrated that this method can be
used to optimize the machine performance of a light source online. In our
study, taking BEPCII as an example, the feasibility of online tuning of the
luminosity in a circular collider is explored, through numerical simulation and
preliminary online experiments. It is shown that the luminosity that is
artificially decreased by a deviation of beam orbital offset from optimal
trajectory can be recovered with this method.
| arxiv topic:physics.acc-ph |
arxiv_dataset-61011503.07386 | Darboux normal form theorem as an example of Liouville integrability
theorem
math.SG
The note offers a proof of Darboux and Liouville theorems from a symplectic
group action perspective.
| arxiv topic:math.SG |
arxiv_dataset-61021503.07486 | On the viability of m**2 phi**2 and natural inflation
astro-ph.CO hep-ph hep-th
In the context of single field inflation, models with a quadratic potential
and models with a natural potential with subplanckian decay constant are in
tension with the Planck data. We show that, when embedded in a two-field model
with an additional super massive field, they can become consistent with
observations. Our results follow if the inflaton is the phase of a complex
field (or an angular variable) protected by a mildly broken U(1) symmetry, and
the radial component, whose mass is much greater than the Hubble scale, is
stabilized at subplanckian values. The presence of the super massive field,
besides modifying the effective single field potential, causes a reduction in
the speed of sound of the inflaton fluctuations, which drives the prediction
for the primordial spectrum towards the allowed experimental values. We discuss
these effects also for the linear potential, and show that this model increases
its agreement with data as well
| arxiv topic:astro-ph.CO hep-ph hep-th |
arxiv_dataset-61031503.07586 | Characterization of Low-mass, Wide-separation Substellar Companions to
Stars in Upper Scorpius: Near-infrared Photometry and Spectroscopy
astro-ph.SR
We present new 0.9-2.45 $\mu$m spectroscopy ($R \sim 1000$), and $Y$, $J$,
$H$, $K_s$, $L^\prime$ photometry, obtained at Gemini North, of three low-mass
brown dwarf companions on wide orbits around young stars of the Upper Scorpius
OB association: HIP 78530 B, [PGZ2001] J161031.9-191305 B, and GSC 06214-00210
B. We use these data to assess the companions' spectral type, temperature,
surface gravity and mass, as well as the ability of the BT-Settl and
Drift-Phoenix atmosphere models to reproduce the spectral features of young
substellar objects. For completeness, we also analyze the archival spectroscopy
and photometry of the Upper Scorpius planetary mass companion 1RXS
J160929.1-210524 b. Based on a comparison with model spectra we find that the
companions, in the above order, have effective temperatures of 2700, 2500, 2300
and 1700 K. These temperatures are consistent with our inferred spectral types,
respectively M7 $\beta$, M9 $\gamma$, M9 $\gamma$, and L4 $\gamma$. From
bolometric luminosities estimated from atmosphere model spectra adjusted to our
photometry, and using evolution models at 5-10 Myr, we estimate masses of
21-25, 28-70, 14-17 and 7-12 $M_{\rm Jup}$, respectively. J1610-1913 B appears
significantly over-luminous for its inferred temperature, which explains its
higher mass estimate. Synthetic spectra based on the BT-Settl and Drift-Phoenix
atmosphere models generally offer a good fit to our observed spectra, although
our analysis has highlighted a few problems. For example, the best fits in the
individual near-infrared bands occur at different model temperatures. Also,
temperature estimates based on a comparison of the broadband magnitudes and
colors of the companions to synthetic magnitudes from the models are
systematically lower than the temperature estimates based on a comparison with
synthetic spectra.
| arxiv topic:astro-ph.SR |
arxiv_dataset-61041503.07686 | How to model the covariance structure in a spatial framework: variogram
or correlation function?
math.ST stat.TH
The basic Kriging's model assumes a Gaussian distribution with stationary
mean and stationary variance. In such a setting, the joint distribution of the
spatial process is characterized by the common variance and the correlation
matrix or, equivalently, by the common variance and the variogram matrix. We
discuss in in detail the option to actually use the variogram as a
parameterization.
| arxiv topic:math.ST stat.TH |
arxiv_dataset-61051503.07786 | Measurement of the cosmic ray spectrum above $4{\times}10^{18}$ eV using
inclined events detected with the Pierre Auger Observatory
astro-ph.HE hep-ex
A measurement of the cosmic-ray spectrum for energies exceeding
$4{\times}10^{18}$ eV is presented, which is based on the analysis of showers
with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$
eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with
index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by
a smooth suppression region. For the energy ($E_\text{s}$) at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
$E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$
eV.
| arxiv topic:astro-ph.HE hep-ex |
arxiv_dataset-61061503.07886 | The Geometry of Supermanifolds and New Supersymmetric Actions
hep-th math-ph math.MP
We construct the Hodge dual for supermanifolds by means of the Grassmannian
Fourier transform of superforms. In the case of supermanifolds it is known that
the superforms are not sufficient to construct a consistent integration theory
and that the integral forms are needed. They are distribution-like forms which
can be integrated on supermanifolds as a top form can be integrated on a
conventional manifold. In our construction of the Hodge dual of superforms they
arise naturally. The compatibility between Hodge duality and supersymmetry is
exploited and applied to several examples. We define the irreducible
representations of supersymmetry in terms of integral and superforms in a new
way which can be easily generalised to several models in different dimensions.
The construction of supersymmetric actions based on the Hodge duality is
presented and new supersymmetric actions with higher derivative terms are
found. These terms are required by the invertibility of the Hodge operator.
| arxiv topic:hep-th math-ph math.MP |
arxiv_dataset-61071503.07986 | Generating clones with conservative near-unanimity operation
math.LO
Due to the Baker-Pixley theorem we know that every clone over a finite domain
$A$ containing a near-unanimity operation $g$ is finitely generated. Therefore
there exists an integer $k$ such that the clone is generated by its $k$-ary
part. In this paper we are interested in the size of $k$ for a fixed $A$ and
fixed arity of a conservative $g$. We obtain lower bounds for all arities and
they turn out to be sharp for arity three.
| arxiv topic:math.LO |
arxiv_dataset-61081503.08086 | A simple renormalization flow for FK-percolation models
math.PR math-ph math.MP
We present a setup that enables to define in a concrete way a renormalization
flow for the FK-percolation models from statistical physics (that are closely
related to Ising and Potts models). In this setting that is applicable in any
dimension of space, one can interpret perturbations of the critical
(conjectural) scaling limits in terms of stationary distributions for rather
simple Markov processes on spaces of abstract discrete weighted graphs.
| arxiv topic:math.PR math-ph math.MP |
arxiv_dataset-61091503.08186 | Riemannian metrics on an infinite dimensional symplectic group
math.DG math.OA
The aim of this paper is the geometric study of the symplectic operators
which are a perturbation of the identity by a Hilbert-Schmidt operator. This
subgroup of the symplectic group was introduced in Pierre de la Harpe's
classical book of Banach-Lie groups. Throughout this paper we will endow the
tangent spaces with different Riemannian metrics. We will use the minimal
curves of the unitary group and the positive invertible operators to compare
the length of the geodesic curves in each case. Moreover we will study the
completeness of the symplectic group with the geodesic distance.
| arxiv topic:math.DG math.OA |
arxiv_dataset-61101503.08286 | The Necessary And Sufficient Condition for Generalized Demixing
cs.SY math.OC
Demixing is the problem of identifying multiple structured signals from a
superimposed observation. This work analyzes a general framework, based on
convex optimization, for solving demixing problems. We present a new solution
to determine whether or not a specific convex optimization problem built for
generalized demixing is successful. This solution will also bring about the
possibility to estimate the probability of success by the approximate kinematic
formula.
| arxiv topic:cs.SY math.OC |
arxiv_dataset-61111503.08386 | Prime Vertex Labelings of Several Families of Graphs
math.CO
A simple and connected $n$-vertex graph has a prime vertex labeling if the
vertices can be injectively labeled with the integers $1, 2, 3,\ldots, n$, such
that adjacent vertices have relatively prime labels. We will present previously
unknown prime vertex labelings for new families of graphs including cycle
pendant stars, cycle chains, prisms, and generalized books.
| arxiv topic:math.CO |
arxiv_dataset-61121503.08486 | Extremely Thin Dielectric Metasurface for Carpet Cloaking
physics.optics
We demonstrate a novel and simple approach to cloaking a scatterer on a
ground plane. We use an extremely thin dielectric metasurface ({\lambda}/12) to
reshape the wavefronts distorted by a scatterer in order to mimic the
reflection pattern of a flat ground plane. To achieve such carpet cloaking, the
reflection angle has to be equal to the incident angle everywhere on the
scatterer. We use a graded metasurface and calculate the required phase
gradient to achieve cloaking. Our metasurface locally provides additional phase
to the wavefronts to compensate for the phase difference amongst light paths
induced by the geometrical distortion. We design our metasurface in the
microwave range using highly sub-wavelength dielectric resonators. We verify
our design by full-wave time-domain simulations using micro-structured
resonators and show that results match theory very well. This approach can be
applied to hide any scatterer on a ground plane not only at microwave
frequencies, but also at higher frequencies up to the near infrared.
| arxiv topic:physics.optics |
arxiv_dataset-61131503.08586 | New class of distortion risk measures and their tail asymptotics with
emphasis on VaR
q-fin.RM
Distortion risk measures are extensively used in finance and insurance
applications because of their appealing properties. We present three methods to
construct new class of distortion functions and measures. The approach involves
the composting methods, the mixing methods and the approach that based on the
theory of copula. Subadditivity is an important property when aggregating risks
in order to preserve the benefits of diversification. However, Value at risk
(VaR), as the most well-known example of distortion risk measure is not always
globally subadditive, except of elliptically distributed risks. In this paper,
instead of study subadditivity we investigate the tail subadditivity for VaR
and other distortion risk measures. In particular, we demonstrate that VaR is
tail subadditive for the case where the support of risk is bounded. Various
examples are also presented to illustrate the results.
| arxiv topic:q-fin.RM |
arxiv_dataset-61141503.08686 | An eigenproblem approach to optimal equal-precision sample allocation in
subpopulations
math.ST stat.TH
Allocation of samples in stratified and/or multistage sampling is one of the
central issues of sampling theory. In a survey of a population often the
constraints for precision of estimators of subpopulations parameters have to be
taken care of during the allocation of the sample. Such issues are often solved
with mathematical programming procedures. In many situations it is desirable to
allocate the sample, in a way which forces the precision of estimates at the
subpopulations level to be both: optimal and identical, while the constraints
of the total (expected) size of the sample (or samples, in two-stage sampling)
are imposed. Here our main concern is related to two-stage sampling schemes. We
show that such problem in a wide class of sampling plans has an elegant
mathematical and computational solution. This is done due to a suitable
definition of the optimization problem, which enables to solve it through a
linear algebra setting involving eigenvalues and eigenvectors of matrices
defined in terms of some population quantities. As a final result we obtain a
very simple and relatively universal method for calculating the subpopulation
optimal and equal-precision allocation which is based on one of the most
standard algorithms of linear algebra (available e.g. in R software).
Theoretical solutions are illustrated through a numerical example based on the
Labour Force Survey. Finally, we would like to stress that the method we
describe, allows to accommodate quite automatically for different levels of
precision priority for subpopulations.
| arxiv topic:math.ST stat.TH |
arxiv_dataset-61151503.08786 | Automorphism groups of endomorphism semigroups of free periodic groups
math.GR
In this paper we describe the automorphism groups of the endomorphism
semigroups of free Burnside groups $B(m,n)$ for odd exponents $n\ge1003$. We
prove, that the groups $Aut(End(B(m,n)))$ and $Aut(B(m,n))$ are isomorphic. In
particular, if the groups $Aut(End(B(m,n)))$ and $Aut(End(B(k,n)))$ are
isomorphic, then $m=k$.
| arxiv topic:math.GR |
arxiv_dataset-61161503.08886 | A Bayesian Change Point Model for Detecting Land Cover Changes in MODIS
Time Series
stat.AP stat.ME
As both a central task in Remote Sensing and a common problem in many other
situations involving time series data, change point detection boasts a thorough
and well-documented history of study. However, the treatment of missing data
and proper exploitation of the structure in multivariate time series during
change point detection remains lacking. Multispectral, high temporal resolution
time series data from NASA's Moderate Resolution Imaging Spectroradiometer
(MODIS) instruments provide an attractive and challenging context to contribute
to the change point detection literature. In an effort to better monitor change
in land cover using MODIS data, we present a novel approach to identifying
periods of time in which regions experience some conversion-type of land cover
change. That is, we propose a method for parameter estimation and change point
detection in the presence of missing data which capitalizes on the high
dimensionality of MODIS data. We test the quality of our method in a simulation
study alongside a contemporary change point method and apply it in a case study
at the Xingu River Basin in the Amazon. Not only does our method maintain a
high accuracy, but can provide insight into the types of changes occurring via
land cover conversion probabilities. In this way we can better characterize the
amount and types of forest disturbance in our study area in comparison to
traditional change point methods.
| arxiv topic:stat.AP stat.ME |
arxiv_dataset-61171503.08986 | Constant-intensity waves and their modulation instability in
non-Hermitian potentials
physics.optics nlin.CD quant-ph
In all of the diverse areas of science where waves play an important role,
one of the most fundamental solutions of the corresponding wave equation is a
stationary wave with constant intensity. The most familiar example is that of a
plane wave propagating in free space. In the presence of any Hermitian
potential, a wave's constant intensity is, however, immediately destroyed due
to scattering. Here we show that this fundamental restriction is conveniently
lifted when working with non-Hermitian potentials. In particular, we present a
whole new class of waves that have constant intensity in the presence of linear
as well as of nonlinear inhomogeneous media with gain and loss. These solutions
allow us to study, for the first time, the fundamental phenomenon of modulation
instability in an inhomogeneous environment. Our results pose a new challenge
for the experiments on non-Hermitian scattering that have recently been put
forward.
| arxiv topic:physics.optics nlin.CD quant-ph |
arxiv_dataset-61181503.09086 | First observation and measurement of the branching fraction for the
decay $B^0_s \to D_s^{*\mp} K^{\pm}$
hep-ex
The first observation of the $B^0_s \to D_s^{*\mp} K^{\pm}$ decay is reported
using 3.0$fb^{-1}$ of proton-proton collision data collected by the LHCb
experiment. The $D_s^{*\mp}$ mesons are reconstructed through the decay chain
$D_s^{*\mp} \to \gamma D_s^{\mp}(K^{\mp}K^{\pm}\pi^{\mp})$. The branching
fraction relative to that for $B^0_s \to D_s^{*-} \pi^{+}$ is measured to be
$0.068 \pm 0.005 ^{+0.003}_{-0.002}$, where the first uncertainty is
statistical and the second is systematic. Using a recent measurement of
$BR(B^0_s \to D_s^{*-} \pi^{+})$ the absolute branching fraction of $B^0_s \to
D_s^{*\mp} K^{\pm}$ is measured as ( 16.3 $\pm$ 1.2 (stat) $^{+0.7}_{-0.5}$
(syst) $\pm$ 4.8 (norm) ) $\times$ 10$^{-5}$, where the third uncertainty is
due to the uncertainty on the branching fraction of the normalisation channel.
| arxiv topic:hep-ex |
arxiv_dataset-61191503.09186 | Electron localization and optical absorption of polygonal quantum rings
cond-mat.mes-hall
We investigate theoretically polygonal quantum rings and focus mostly on the
triangular geometry where the corner effects are maximal. Such rings can be
seen as short core-shell nanowires, a generation of semiconductor
heterostructures with multiple applications. We show how the geometry of the
sample determines the electronic energy spectrum, and also the localization of
electrons, with effects on the optical absorption. In particular, we show that
irrespective of the ring shape low-energy electrons are always attracted by
corners and are localized in their vicinity. The absorption spectrum in the
presence of a magnetic field shows only two peaks within the corner-localized
state domain, each associated with different circular polarization. This
picture may be changed by an external electric field which allows previously
forbidden transitions, and thus enables the number of corners to be determined.
We show that polygonal quantum rings allow absorption of waves from distant
ranges of the electromagnetic spectrum within one sample.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-61201504.00095 | Inverse design and demonstration of a compact and broadband on-chip
wavelength demultiplexer
physics.optics
Integrated photonic devices are poised to play a key role in a wide variety
of applications, ranging from optical interconnects and sensors to quantum
computing. However, only a small library of semi-analytically designed devices
are currently known. In this paper, we demonstrate the use of an inverse design
method that explores the full design space of fabricable devices and allows us
to design devices with previously unattainable functionality, higher
performance and robustness, and smaller footprints compared to conventional
devices. We designed a silicon wavelength demultiplexer that splits
$1300~\mathrm{nm}$ and $1550~\mathrm{nm}$ light from an input waveguide into
two output waveguides, and fabricated and characterized several devices. The
devices display low insertion loss $\left(2 - 4~\mathrm{dB}\right)$, high
contrast $\left(12 - 17~\mathrm{dB}\right)$, and wide bandwidths $\left(\sim
100~\mathrm{nm} \right)$. The device footprint is $2.8 \times 2.8 ~\mathrm{\mu
m}$, making this the smallest dielectric wavelength splitter to date.
| arxiv topic:physics.optics |
arxiv_dataset-61211504.00195 | Ultralong Lifetime Plasmons on Picosecond Time Scale Enabled by Hybrid
Plasmon-Phonon Polaritons
cond-mat.mtrl-sci cond-mat.mes-hall
Graphene plasmonics is of great interest for compact optical devices working
in broad frequency domains with ultrahigh speed and very low energy
consumption. However, graphene plasmons damp out quickly on most substrates
mainly due to scattering loss from substrate surface phonons and impurities.
Here we discover a new hybridized plasmon-phonon polariton mode in
graphene/h-BN van der Waals heterostructures, which enables ultralong hybrid
plasmon lifetime up to 1.6 picosecond, the longest plasmon lifetime ever
demonstrated. Such remarkably long lifetime arises from the coupling of
long-lifetime h-BN transverse optical phonon with graphene plasmons, which
uniquely exists in monolayer heterostructures. Our findings and understanding
of this unexploited hybrid mode offer a novel approach to tune the plasmon
behaviours in the frequency, time and space domains. This can potentially
introduce a new paradigm to generate highly-confined plasmons with ultra-long
lifetime for various applications, such as deep-subwavelength metamaterials,
ultra-low-loss waveguides, and ultrafast optical switches.
| arxiv topic:cond-mat.mtrl-sci cond-mat.mes-hall |
arxiv_dataset-61221504.00295 | Tensor perturbations in a general class of Palatini theories
gr-qc astro-ph.CO hep-th
We study a general class of gravitational theories formulated in the Palatini
approach and derive the equations governing the evolution of tensor
perturbations. In the absence of torsion, the connection can be solved as the
Christoffel symbols of an auxiliary metric which is non-trivially related to
the space-time metric. We then consider background solutions corresponding to a
perfect fluid and show that the tensor perturbations equations (including
anisotropic stresses) for the auxiliary metric around such a background take an
Einstein-like form. This facilitates the study in a homogeneous and isotropic
cosmological scenario where we explicitly establish the relation between the
auxiliary metric and the space-time metric tensor perturbations. As a general
result, we show that both tensor perturbations coincide in the absence of
anisotropic stresses.
| arxiv topic:gr-qc astro-ph.CO hep-th |
arxiv_dataset-61231504.00395 | Introduction \`a l'\'equation de Burgers stochastique et \`a la
burgulence
math.AP
This paper is an introduction to the theory of 1d stochastic Burgers equation
under periodic boundary conditions and with a stochastic force, sufficiently
smooth in the space variable. We prove the classical results on the existence
and uniqueness of solutions, study their regularity and discuss their
properties when the time goes to infinity or the viscosity goes to zero. The
latter limit describes the turbulence in the Burgers equation, named by U.
Frish "the burgulence". Our paper may be used as an elementary introduction to
the modern methods of stochastic PDE.
| arxiv topic:math.AP |
arxiv_dataset-61241504.00495 | Exploring the complex pattern of information spreading in online blog
communities
physics.soc-ph cs.SI
Information spreading in online social communities has attracted tremendous
attention due to its utmost practical values in applications. Despite that
several individual-level diffusion data have been investigated, we still lack
the detailed understanding of the spreading pattern of information. Here, by
comparing information flows and social links in a blog community, we find that
the diffusion processes are induced by three different spreading mechanisms:
social spreading, self-promotion and broadcast. Although numerous previous
studies have employed epidemic spreading models to simulate information
diffusion, we observe that such models fail to reproduce the realistic
diffusion pattern. In respect to users behaviors, strikingly, we find that most
users would stick to one specific diffusion mechanism. Moreover, our
observations indicate that the social spreading is not only crucial for the
structure of diffusion trees, but also capable of inducing more subsequent
individuals to acquire the information. Our findings suggest new directions for
modeling of information diffusion in social systems and could inform design of
efficient propagation strategies based on users behaviors.
| arxiv topic:physics.soc-ph cs.SI |
arxiv_dataset-61251504.00595 | Adaptive Density Estimation on the Circle by Nearly-Tight Frames
math.ST stat.TH
This work is concerned with the study of asymptotic properties of
nonparametric density estimates in the framework of circular data. The
estimation procedure here applied is based on wavelet thresholding methods: the
wavelets used are the so-called Mexican needlets, which describe a nearly-tight
frame on the circle. We study the asymptotic behaviour of the $L^{2}$-risk
function for these estimates, in particular its adaptivity, proving that its
rate of convergence is nearly optimal.
| arxiv topic:math.ST stat.TH |
arxiv_dataset-61261504.00695 | Trading query complexity for sample-based testing and multi-testing
scalability
cs.CC
We show here that every non-adaptive property testing algorithm making a
constant number of queries, over a fixed alphabet, can be converted to a
sample-based (as per [Goldreich and Ron, 2015]) testing algorithm whose average
number of queries is a fixed, smaller than $1$, power of $n$. Since the query
distribution of the sample-based algorithm is not dependent at all on the
property, or the original algorithm, this has many implications in scenarios
where there are many properties that need to be tested for concurrently, such
as testing (relatively large) unions of properties, or converting a
Merlin-Arthur Proximity proof (as per [Gur and Rothblum, 2013]) to a proper
testing algorithm.
The proof method involves preparing the original testing algorithm for a
combinatorial analysis, which in turn involves a new result about the existence
of combinatorial structures (essentially generalized sunflowers) that allow the
sample-based tester to replace the original constant query complexity tester.
| arxiv topic:cs.CC |
arxiv_dataset-61271504.00795 | On regular Stein neighborhoods of a union of two totally real planes in
$\mathbb{C}^2$
math.CV
In this paper we find regular Stein neighborhoods for a union of totally real
planes $M=(A+iI)\mathbb{R}^2$ and $N=\mathbb{R}^2$ in $\mathbb{C}^2$ provided
that the entries of a real $2 \times 2$ matrix $A$ are sufficiently small. A
key step in our proof is a local construction of a suitable function $\rho$
near the origin. The sublevel sets of $\rho$ are strongly Levi pseudoconvex and
admit strong deformation retraction to $M\cup N$.
| arxiv topic:math.CV |
arxiv_dataset-61281504.00895 | The effect of the magnon dispersion on the longitudinal spin Seebeck
effect in yttrium iron garnets (YIG)
cond-mat.mtrl-sci
We study the temperature dependence of the longitudinal spin-Seebeck effect
(LSSE) in a yttrium iron garnet Y3Fe5O12 (YIG) / Pt system for samples of
different thicknesses. In this system, the thermal spin torque is
magnon-driven. The LSSE signal peaks at a specific temperature that depends on
the YIG sample thickness. We also observe freeze-out of the LSSE signal at high
magnetic fields, which we attribute to the opening of an energy gap in the
magnon dispersion. We observe partial freeze-out of the LSSE signal even at
room temperature, where kBT is much larger than the gap. This suggests that a
subset of the magnon population with an energy below kB x TC (TC about 40 K)
contribute disproportionately to the LSSE; at temperatures below TC, we label
these magnons subthermal magnons. The T-dependence of the LSSE at temperatures
below the maximum is interpreted in terms of a new empirical model that
ascribes most of the temperature dependence to that of the thermally driven
magnon flux.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-61291504.00995 | Dyakonov surface waves in lossy metamaterials
physics.optics
We analyze the existence of localized waves in the vicinities of the
interface between two dielectrics, provided one of them is uniaxial and lossy.
We found two families of surface waves, one of them approaching the well-known
Dyakonov surface waves (DSWs). In addition, a new family of wave fields exists
which are tightly bound to the interface. Although its appearance is clearly
associated with the dissipative character of the anisotropic material, the
characteristic propagation length of such surface waves might surpasses the
working wavelength by nearly two orders of magnitude.
| arxiv topic:physics.optics |
arxiv_dataset-61301504.01095 | Kodaira dimension of algebraic fiber spaces over abelian varieties
math.AG
In this short article we provide a proof of the Iitaka conjecture for
algebraic fiber spaces over abelian varieties.
| arxiv topic:math.AG |
arxiv_dataset-61311504.01195 | Constraints on the basic parameters of dark matter using the Planck data
astro-ph.CO
Dark Matter annihilation or decay can affect the anisotropy of the cosmic
microwave background (CMB). Therefore, the CMB data can be used to constrain
the properties of a dark matter particle. In this work, we use the new CMB data
obtained by the Planck satellite to investigate the limits on the basic
parameters of a dark matter particle. The parameters are the dark matter mass
($m_{\chi}$) and the thermally averaged cross section ($\langle\sigma
v\rangle$) for dark matter annihilation and the decay rate ($\Gamma$) (or
lifetime $\tau = 1/\Gamma$) for dark matter decay. For dark matter annihilation
we also consider the impact of the structure formation process which is
neglected by the recent work. We find that for DM annihilation, the constraints
on the parameters are $f_{ann}=\langle \sigma v\rangle /m_{\chi}< 0.16 \times
10^{-26} \mathrm{cm^{3}s^{-1}GeV^{-1}}$(or $f_{ann}<0.89 \times 10^{-6}
\mathrm{m^{3}s^{-1}kg^{-1}}$, $95\%$ C.L.). For DM decay, the constraints on
the decay rate are $\Gamma < 0.28 \times 10^{-25} \mathrm{s^{-1}}$($95\%$
C.L.).
| arxiv topic:astro-ph.CO |
arxiv_dataset-61321504.01295 | Axion Induced Oscillating Electric Dipole Moments
hep-ph astro-ph.CO hep-ex hep-th nucl-ex
The axion electromagnetic anomaly induces an oscillating electric dipole for
{\em any} static magnetic dipole. Static electric dipoles do not produce
oscillating magnetic moments. This is a low energy theorem which is a
consequence of the space-time dependent cosmic background field of the axion in
the limit that it is only locally time dependent $(\overrightarrow{\beta}=0)$.
The electron will acquire an oscillating electric dipole of frequency $m_a$ and
strength $\sim 10^{-32}$ e-cm, three orders of magnitude above the nucleon, and
within four orders of magnitude of the present standard model DC limit. This
may suggest sensitive new experimental venues for the axion dark matter search.
| arxiv topic:hep-ph astro-ph.CO hep-ex hep-th nucl-ex |
arxiv_dataset-61331504.01395 | Dark Matter Searches with a Mono-Z' jet
hep-ph
We study collider signatures of a class of dark matter models with a
GeV-scale dark Z'. At hadron colliders, the production of dark matter particles
naturally leads to associated production of the Z', which can appear as a
narrow jet after it decays hadronically. Contrary to the usual mono-jet signal
from initial state radiation, the final state radiation of dark matter can
generate the signature of a mono-Z' jet plus missing transverse energy.
Performing a jet-substructure analysis to tag the Z' jet, we show that these Z'
jets can be distinguished from QCD jets at high significance. Compared to
mono-jets, a dedicated search for mono-Z' jet events can lead to over an order
of magnitude stronger bounds on the interpreted dark matter-nucleon scattering
cross sections.
| arxiv topic:hep-ph |
arxiv_dataset-61341504.01495 | Second Order perturbation Theory: A covariant approach involving a
barotropic equation of state
gr-qc
We present a covariant and gauge invariant formalism suited to the study of
second-order effects associated with higher order tensor perturbations. The
analytical method we have developed enables us to characterize pure
second-order tensor perturbations about FLRW model having different kinds of
equations of state. Our analysis of the radiation case suggests that it may be
feasible to examine the CMB polarization arising from higher order
perturbations.
| arxiv topic:gr-qc |
arxiv_dataset-61351504.01595 | Construction of multi-solitons for the energy-critical wave equation in
dimension 5
math.AP
We construct 2-solitons of any speed of the focusing energy-critical
nonlinear wave equation in dimension 5. The existence result also holds for the
case of K-solitons, for any K >2, assuming that the speeds are collinear. The
main difficulty of the construction is the strong interaction between the
solitons due to the slow spatial decay of the single soliton. This is in
contrast with previous constructions of multi-solitons for other nonlinear
models (like generalized KdV and nonlinear Schrodinger equations in energy
subcritical cases), where the interactions are exponentially small in time due
to the exponential decay of the solitons.
| arxiv topic:math.AP |
arxiv_dataset-61361504.01695 | Quasirelativistic calculation of 4s$^2$4p$^5$, 4s$^2$4p$^4$4d and
4s4p$^6$ configuration spectroscopic parameters for the W$^{39+}$ ion
physics.atom-ph
The ab initio quasirelativistic Hartree-Fock method developed specifically
for the calculation of spectral parameters of heavy atoms and highly charged
ions is used to derive spectral data for the 4s$^2$4p$^5$, 4s$^2$4p$^4$4d and
4s4p$^6$ configurations of the multicharged tungsten ion W$^{39+}$. The
relativistic effects are taken into account in the Breit-Pauli approximation
for the quasirelativistic Hartree-Fock radial orbitals. The configuration
interaction method is applied to include the electron correlation effects.
Produced data are compared with existing experimental measurements and
theoretical calculations.
| arxiv topic:physics.atom-ph |
arxiv_dataset-61371504.01795 | Skyrmion-number dependence of spin-transfer torque on magnetic bubbles
cond-mat.mes-hall
We theoretically study the skyrmion-number dependence of spin-transfer torque
acting on magnetic bubbles. The skymrion number of magnetic bubbles can take
any integer value depending on the magnetic profile on its circumference and
the size of the bubble. We find that the transverse motion of a bubble with
respect to the charge current is greatly suppressed as the absolute value of
skyrmion number departs from unity, whereas the longitudinal motion is less
sensitive.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-61381504.01895 | Maximal green sequences for preprojective algebras
math.RT hep-th
Maximal green sequences were introduced as combinatorical counterpart for
Donaldson-Thomas invariants for 2-acyclic quivers with potential by B. Keller.
We take the categorical notion and introduce maximal green sequences for hearts
of bounded t-structures of triangulated categories that can be tilted
indefinitely. We study the case where the heart is the category of modules over
the preprojective algebra of a quiver without loops. The combinatorical
counterpart of maximal green sequences for Dynkin quivers are maximal chains in
the Hasse quiver of basic support \tau -tilting modules.
We show that a quiver has a maximal green sequence if and only if it is of
Dynkin type. More generally, we study module categories for finite- dimensional
algebras with finitely many bricks.
| arxiv topic:math.RT hep-th |
arxiv_dataset-61391504.01995 | Solving the Closest Vector Problem in $2^n$ Time--- The Discrete
Gaussian Strikes Again!
cs.DS
We give a $2^{n+o(n)}$-time and space randomized algorithm for solving the
exact Closest Vector Problem (CVP) on $n$-dimensional Euclidean lattices. This
improves on the previous fastest algorithm, the deterministic
$\widetilde{O}(4^{n})$-time and $\widetilde{O}(2^{n})$-space algorithm of
Micciancio and Voulgaris.
We achieve our main result in three steps. First, we show how to modify the
sampling algorithm from [ADRS15] to solve the problem of discrete Gaussian
sampling over lattice shifts, $L- t$, with very low parameters. While the
actual algorithm is a natural generalization of [ADRS15], the analysis uses
substantial new ideas. This yields a $2^{n+o(n)}$-time algorithm for
approximate CVP for any approximation factor $\gamma = 1+2^{-o(n/\log n)}$.
Second, we show that the approximate closest vectors to a target vector $t$ can
be grouped into "lower-dimensional clusters," and we use this to obtain a
recursive reduction from exact CVP to a variant of approximate CVP that
"behaves well with these clusters." Third, we show that our discrete Gaussian
sampling algorithm can be used to solve this variant of approximate CVP.
The analysis depends crucially on some new properties of the discrete
Gaussian distribution and approximate closest vectors, which might be of
independent interest.
| arxiv topic:cs.DS |
arxiv_dataset-61401504.02095 | Evidence of boosted 13CO/12CO ratio in early-type galaxies in dense
environments
astro-ph.GA
We present observations of $^{13}$CO(1-0) in 17 Combined Array for Research
in Millimeter Astronomy (CARMA) Atlas3D early-type galaxies (ETGs), obtained
simultaneously with $^{12}$CO(1-0) observations. The $^{13}$CO in six ETGs is
sufficiently bright to create images. In these 6 sources, we do not detect any
significant radial gradient in the $^{13}$CO/$^{12}$CO ratio between the
nucleus and the outlying molecular gas. Using the $^{12}$CO channel maps as 3D
masks to stack the $^{13}$CO emission, we are able to detect 15/17 galaxies to
$>3\sigma$ (and 12/17 to at least 5$\sigma$) significance in a spatially
integrated manner. Overall, ETGs show a wide distribution of
$^{13}$CO/$^{12}$CO ratios, but Virgo cluster and group galaxies preferentially
show a $^{13}$CO/$^{12}$CO ratio about 2 times larger than field galaxies,
although this could also be due to a mass dependence, or the CO spatial extent
($R_{\rm CO}/R_{\rm e}$). ETGs whose gas has a morphologically-settled
appearance also show boosted $^{13}$CO/$^{12}$CO ratios. We hypothesize that
this variation could be caused by (i) the extra enrichment of gas from
molecular reprocessing occurring in low-mass stars (boosting the abundance of
$^{13}$C to $^{12}$C in the absence of external gas accretion), (ii) much
higher pressure being exerted on the midplane gas (by the intracluster medium)
in the cluster environment than in isolated galaxies, or (iii) all but the
densest molecular gas clumps being stripped as the galaxies fall into the
cluster. Further observations of $^{13}$CO in dense environments, particularly
of spirals, as well as studies of other isotopologues, should be able to
distinguish between these hypotheses.
| arxiv topic:astro-ph.GA |
arxiv_dataset-61411504.02195 | Small data solutions of the Vlasov-Poisson system and the vector field
method
math.AP
The aim of this article is to demonstrate how the vector field method of
Klainerman can be adapted to the study of transport equations. After an
illustration of the method for the free transport operator, we apply the vector
field method to the Vlasov-Poisson system in dimension 3 or greater. The main
results are optimal decay estimates and the propagation of global bounds for
commuted fields associated with the conservation laws of the free transport
operators, under some smallness assumption. Similar decay estimates had been
obtained previously by Hwang, Rendall and Vel\'azquez using the method of
characteristics, but the results presented here are the first to contain the
global bounds for commuted fields and the optimal spatial decay estimates. In
dimension 4 or greater, it suffices to use the standard vector fields commuting
with the free transport operator while in dimension 3, the rate of decay is
such that these vector fields would generate a logarithmic loss. Instead, we
construct modified vector fields where the modification depends on the solution
itself. The methods of this paper, being based on commutation vector fields and
conservation laws, are applicable in principle to a wide range of systems,
including the Einstein-Vlasov and the Vlasov-Nordstr\"om system.
| arxiv topic:math.AP |
arxiv_dataset-61421504.02295 | Cosmological bounds on open FLRW solutions of massive gravity
gr-qc astro-ph.CO
In this work we have analysed some cosmological bounds concerning an open
FLRW solution of massive gravity. The constraints with recent observational
$H(z)$ data were found and the best fit values for the cosmological parameters
are in agreement with the $\Lambda$CDM model, and also point to a nearly open
spatial curvature, as expected from the model. The graviton mass dependence
with the constant parameters $\alpha_3$ and $\alpha_4$, related to the
additional lagrangians terms of the model, are also analysed, and we have
obtained a strong dependence with such parameters, although the condition
$m_g\simeq H_0^{-1}$ seems dominant for a long range of the parameters
$\alpha_3$ and $\alpha_4$.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-61431504.02395 | Bridging the gap between general probabilistic theories and the
device-independent framework for nonlocality and contextuality
quant-ph cs.CR cs.GT cs.LO math-ph math.MP
Characterizing quantum correlations in terms of information-theoretic
principles is a popular chapter of quantum foundations. Traditionally, the
principles adopted for this scope have been expressed in terms of conditional
probability distributions, specifying the probability that a black box produces
a certain output upon receiving a certain input. This framework is known as
"device-independent". Another major chapter of quantum foundations is the
information-theoretic characterization of quantum theory, with its sets of
states and measurements, and with its allowed dynamics. The different
frameworks adopted for this scope are known under the umbrella term "general
probabilistic theories". With only a few exceptions, the two programmes on
characterizing quantum correlations and characterizing quantum theory have so
far proceeded on separate tracks, each one developing its own methods and its
own agenda. This paper aims at bridging the gap, by comparing the two
frameworks and illustrating how the two programmes can benefit each other.
| arxiv topic:quant-ph cs.CR cs.GT cs.LO math-ph math.MP |
arxiv_dataset-61441504.02495 | Gerstenhaber algebra structure on the Hochschild cohomology of quadratic
string algebras
math.RA
We describe the Gerstenhaber algebra structure on the Hochschild cohomology
HH*$(A)$ when $A$ is a quadratic string algebra. First we compute the
Hochschild cohomology groups using Barzdell's resolution and we describe
generators of these groups. Then we construct comparison morphisms between the
bar resolution and Bardzell's resolution in order to get formulae for the cup
product and the Lie bracket. We find conditions on the bound quiver associated
to string algebras in order to get non-trivial structures.
| arxiv topic:math.RA |
arxiv_dataset-61451504.02595 | Error Estimates for Approximating Best Proximity Points for Cyclic
Contractive Maps
math.FA
We find a priori and a posteriori error estimates of the best proximity point
for the Picard iteration associated to a cyclic contraction map, which is
defined on a uniformly convex Banach space with modulus of convexity of power
type. We find the rate of convergence for the Picard sequence.
| arxiv topic:math.FA |
arxiv_dataset-61461504.02695 | Infinite friezes
math.CO
We provide a characterization of infinite frieze patterns of positive
integers via triangulations of an infinite strip in the plane. In the periodic
case, these triangulations may be considered as triangulations of annuli. We
also give a geometric interpretation of all entries of infinite friezes via
matching numbers.
| arxiv topic:math.CO |
arxiv_dataset-61471504.02795 | Condition for the burning of hadronic stars into quark stars
nucl-th astro-ph.SR
We will review the approach used for studying the conversion of a hadronic
star into a quark star based on the assumption of a infinitely thin combustion
zone and we will discuss why, in this scheme, the combustion stops before the
whole hadronic star is converted.
| arxiv topic:nucl-th astro-ph.SR |
arxiv_dataset-61481504.02895 | One-dimensional chain "melting" in incommensurate potassium
cond-mat.mtrl-sci
Between 19 and 54 GPa, potassium has a complex composite incommensurate
host-guest structure which undergoes two intraphase transitions over this
pressure range. The temperature dependence of these host-guest phases is
further complicated by the onset of an order-disorder transition in their guest
chains. Here, we report single crystal, quasi-single crystal, and powder
synchrotron X-ray diffraction measurements of this order-disorder phenomenon in
incommensurate potassium to 47 GPa and 750 K. The so-called chain "melting"
transition is clearly visible over a 22 GPa pressure range, and there are
significant changes in the slope of the phase boundary which divides the
ordered and disordered phases, one of which results from the intraphase
transitions in the guest structure.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-61491504.02995 | An Overview on the Estimation of Large Covariance and Precision Matrices
stat.ME
Estimating large covariance and precision matrices are fundamental in modern
multivariate analysis. The problems arise from statistical analysis of large
panel economics and finance data. The covariance matrix reveals marginal
correlations between variables, while the precision matrix encodes conditional
correlations between pairs of variables given the remaining variables. In this
paper, we provide a selective review of several recent developments on
estimating large covariance and precision matrices. We focus on two general
approaches: rank based method and factor model based method. Theories and
applications of both approaches are presented. These methods are expected to be
widely applicable to analysis of economic and financial data.
| arxiv topic:stat.ME |
arxiv_dataset-61501504.03095 | An Inference Attack Model for Flow Table Capacity and Usage: Exploiting
the Vulnerability of Flow Table Overflow in Software-Defined Network
cs.NI
As the most competitive solution for next-generation network,
software-defined network (SDN) and its dominant implementation OpenFlow, are
attracting more and more interests. But besides convenience and flexibility,
SDN/OpenFlow also introduces new kinds of limitations and security issues. Of
these limitations, the most obvious and maybe the most neglected one, is the
flow table capacity of SDN/OpenFlow switches.
In this paper, we proposed a novel inference attack targeting at SDN/OpenFlow
network, which is motivated by the limited flow table capacities of
SDN/OpenFlow switches and the following measurable network performance decrease
resulting from frequent interactions between data plane and control plane when
the flow table is full. To our best knowledge, this is the first proposed
inference attack model of this kind for SDN/OpenFlow. We also implemented an
inference attack framework according to our model and examined its efficiency
and accuracy. The simulation results demonstrate that our framework can infer
the network parameters(flow table capacity and flow table usage) with an
accuracy of 80% or higher. These findings give us a deeper understanding of
SDN/OpenFlow limitations and serve as guidelines to future improvements of
SDN/OpenFlow.
| arxiv topic:cs.NI |
arxiv_dataset-61511504.03195 | Upper Bounds on the Error of Sparse Vector and Low-Rank Matrix Recovery
cs.IT math.IT
Suppose that a solution $\widetilde{\mathbf{x}}$ to an underdetermined linear
system $\mathbf{b} = \mathbf{A} \mathbf{x}$ is given. $\widetilde{\mathbf{x}}$
is approximately sparse meaning that it has a few large components compared to
other small entries. However, the total number of nonzero components of
$\widetilde{\mathbf{x}}$ is large enough to violate any condition for the
uniqueness of the sparsest solution. On the other hand, if only the dominant
components are considered, then it will satisfy the uniqueness conditions. One
intuitively expects that $\widetilde{\mathbf{x}}$ should not be far from the
true sparse solution $\mathbf{x}_0$. We show that this intuition is the case by
providing an upper bound on $\| \widetilde{\mathbf{x}} - \mathbf{x}_0\|$ which
is a function of the magnitudes of small components of $\widetilde{\mathbf{x}}$
but independent from $\mathbf{x}_0$. This result is extended to the case that
$\mathbf{b}$ is perturbed by noise. Additionally, we generalize the upper
bounds to the low-rank matrix recovery problem.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-61521504.03295 | On boundary behavior of one class of mappings on Riemannian manifolds
math.CV
Theorems on continuous extension on boundary for one class of open discrete
mappings between Riemannian manifolds are obtained. In particular, there is
proved that, open discrete ring $Q$-mappings $f:D\rightarrow D^{\,\prime}$ are
extend to $\partial D$ whenever $\partial D$ is locally connected, $\partial
D^{\,\prime}$ is strongly accessible, and a function $Q$ has finite mean
oscillation at $\partial D.$
| arxiv topic:math.CV |
arxiv_dataset-61531504.03395 | Automated Detection of Solar Eruptions
astro-ph.SR astro-ph.IM
Observation of the solar atmosphere reveals a wide range of motions, from
small scale jets and spicules to global-scale coronal mass ejections.
Identifying and characterizing these motions are essential to advancing our
understanding the drivers of space weather. Both automated and visual
identifications are currently used in identifying CMEs. To date, eruptions near
the solar surface (which may be precursors to CMEs) have been identified
primarily by visual inspection. Here we report on EruptionPatrol (EP): a
software module that is designed to automatically identify eruptions from data
collected by SDO/AIA. We describe the method underlying the module and compare
its results to previous identifications found in the Heliophysics Event
Knowledgebase. EP identifies eruptions events that are consistent with those
found by human annotations, but in a significantly more consistent and
quantitative manner. Eruptions are found to be distributed within 15Mm of the
solar surface. They possess peak speeds ranging from 4 to 100 km/sec and
display a power-law probability distribution over that range. These
characteristics are consistent with previous observations of prominences.
| arxiv topic:astro-ph.SR astro-ph.IM |
arxiv_dataset-61541504.03495 | Exploring plasma evolution during Sagittarius A* flares
astro-ph.HE
We present a new way of describing the flares from Sgr A* with a
self-consistent calculation of the particle distribution. All relevant
radiative processes are taken into account in the evolution of the electron
distribution and resulting spectrum. We present spectral modelling for new
X-ray flares observed by NuSTAR, together with older observations in different
wavelengths, and discuss the changes in plasma parameters to produce a flare.
We show that under certain conditions, the real particle distribution can
differ significantly from standard distributions assumed in most studies. We
conclude that the flares are likely generated by magnetized plasma consistent
with our understanding of the accretion flow. Including non-thermal
acceleration, injection, escape, and cooling losses produces a spectrum with a
break between the infrared and the X-ray, allowing a better simultaneous
description of the different wavelengths. We favour the non-thermal synchrotron
interpretation, assuming the infrared flare spectrum used is representative. We
also consider the effects on Sgr A*s quiescent spectrum in the case of a
density increase due to the G2 encounter with Sgr A*.
| arxiv topic:astro-ph.HE |
arxiv_dataset-61551504.03595 | Modeling and Characterization of Charged Particle Trajectories in an
Oscillating Magnetic Field
physics.class-ph
A constant magnetic field has frequently been discussed and has been known
that it can cause a charged particle to form interesting trajectories such as
cycloid and helix in presence of electric field, but a changing magnetic field
is rarely discussed. In this work, modeling and characterization of charged
particle trajectories in oscillating magnetic field is reported. The modeling
is performed using Euler method with speed corrector. The result shows that
there are two types of trajectory patterns that will recur for every $180 n
T_0$ ($n = 0, 1, 2, ..$) in increasing of magnetic field oscillation period,
where $T_0$ is about $6.25\times10^{-7}$ s.
| arxiv topic:physics.class-ph |
arxiv_dataset-61561504.03695 | On the chirality of the SM and the fermion content of GUTs
hep-ph hep-th
The Standard Model (SM) is a chiral theory, where right- and left-handed
fermion fields transform differently under the gauge group. Extra fermions, if
they do exist, need to be heavy otherwise they would have already been
observed. With no complex mechanisms at work, such as confining interactions or
extra-dimensions, this can only be achieved if every extra right-handed fermion
comes paired with a left-handed one transforming in the same way under the
Standard Model gauge group, otherwise the new states would only get a mass
after electroweak symmetry breaking, which would necessarily be small
($\sim100\textrm{ GeV}$). Such a simple requirement severely constrains the
fermion content of Grand Unified Theories (GUTs). It is known for example that
three copies of the representations $\mathbf{\overline{5}}+\mathbf{10}$ of
$SU(5)$ or three copies of the $\mathbf{16}$ of $SO(10)$ can reproduce the
Standard Model's chirality, but how unique are these arrangements? In a
systematic way, this paper looks at the possibility of having non-standard
mixtures of fermion GUT representations yielding the correct Standard Model
chirality. Family unification is possible with large special unitary groups ---
for example, the $\mathbf{171}$ representation of $SU(19)$ may decompose as
$3\left(\mathbf{16}\right)+\mathbf{120}+3\left(\mathbf{1}\right)$ under
$SO(10)$.
| arxiv topic:hep-ph hep-th |
arxiv_dataset-61571504.03795 | Cartan's Supersymmetry and the Decay of a $H^0(0^+)$
hep-ph
We compare the decay of a Higgs boson $H^0(0^+)\to\ell\bar\ell
\ell\bar\ell\to\gamma\gamma$, $H^0(0^+)\to W\bar W\to \ell\bar\nu\bar\ell\nu$,
and $H^0(0^+)\to Z\bar Z\to\ell\bar\ell\ell\bar\ell$ using Cartan's
supersymmetry, that defines coupling of a vector particle $x_i$ and Dirac
spinors $\psi$ and $\phi$.
Apparent discrepancy of $H^0(0^+)\to\gamma\gamma/\ell\bar\ell \ell\bar\ell$
experimental data of ATLAS and CMS collaborations disappears, since the sum of
transition to $\ell\bar\ell \ell\bar\ell$ and $\gamma\gamma$ have the meaning.
The trilinearity of leptons vector fields coupling and the initial wave
functions to be large components define Higgs-leptons couplings.
The ratio of Higgs boson decay branching ratios $H\to WW=21.6\pm 0.9$,
$H\to\gamma\gamma=0.228\pm 0.011$ can be reproduced when we multiply coupling
constant $\alpha_s\simeq 1$ for $WW$ and $\alpha_e=1/137$ for $\gamma\gamma$ to
the number of independent diagrams.
Comparison with Atiyah-Witten's quark-gluon dynamics on a manifold of $G_2$
holonomy theory is added.
| arxiv topic:hep-ph |
arxiv_dataset-61581504.03895 | Graph representation of balance sheets: from exogenous to endogenous
money
q-fin.EC q-fin.GN
The nature of monetary arrangements is often discussed without any reference
to its detailed construction. We present a graph representation that allows for
a clear understanding of modern monetary systems. First, we show that systems
based on commodity money are incompatible with credit. We then study the
current chartalist systems based on pure fiat money, and we discuss the
consolidation of the central bank with the Treasury. We obtain a visual
explanation about how commercial banks are responsible for endogenous money
creation whereas the Treasury and the central bank are in charge of the total
amount of net money. Finally we draw an analogy between systems based on gold
convertibility and currency pegs to show that fixed exchange rates can never be
maintained.
| arxiv topic:q-fin.EC q-fin.GN |
arxiv_dataset-61591504.03995 | Undecidability of Equality in the Free Locally Cartesian Closed Category
(Extended version)
cs.LO
We show that a version of Martin-L\"of type theory with an extensional
identity type former I, a unit type N1 , Sigma-types, Pi-types, and a base type
is a free category with families (supporting these type formers) both in a 1-
and a 2-categorical sense. It follows that the underlying category of contexts
is a free locally cartesian closed category in a 2-categorical sense because of
a previously proved biequivalence. We show that equality in this category is
undecidable by reducing it to the undecidability of convertibility in
combinatory logic. Essentially the same construction also shows a slightly
strengthened form of the result that equality in extensional Martin-L\"of type
theory with one universe is undecidable.
| arxiv topic:cs.LO |
arxiv_dataset-61601504.04095 | Asymptotic behavior of positive solutions to a degenerate elliptic
equation in the upper half space with a nonlinear boundary condition
math.AP
We consider positive solutions of the problem \begin{equation}
\left\{\begin{array}{l}-\mbox{div}(x_{n}^{a}\nabla u)=0\qquad
\mbox{in}\;\;\mathbb{R}_+^n,\\ \frac{\partial u}{\partial \nu^a}=u^{q} \qquad
\mbox{on}\;\;\partial \mathbb{R}_+^n,\\ \end{array} \right. \end{equation}
where $a\in (-1,0)\cup(0,1)$, $q>1$ and $\frac{\partial u}{\partial
\nu^a}:=-\lim_{x_{n}\rightarrow 0^+}x_{n}^{a}\frac{\partial u}{\partial
x_{n}}$.
We obtain some qualitative properties of positive axially symmetric solutions
in
$n\geq3$ for the case $a\in (-1,0)$ under the condition
$q\geq\frac{n-a}{n+a-2}$. In particular, we establish the asymptotic expansion
of positive axially symmetric solutions.
| arxiv topic:math.AP |
arxiv_dataset-61611504.04195 | Extremal problems on the Hamiltonicity of claw-free graphs
math.CO
In 1962, Erd\H{o}s proved that if a graph $G$ with $n$ vertices satisfies $$
e(G)>\max\left\{\binom{n-k}{2}+k^2,\binom{\lceil(n+1)/2\rceil}{2}+\left\lfloor
\frac{n-1}{2}\right\rfloor^2\right\}, $$ where the minimum degree
$\delta(G)\geq k$ and $1\leq k\leq(n-1)/2$, then it is Hamiltonian. For $n \geq
2k+1$, let $E^k_n=K_{k}\vee (kK_1+K_{n-2k})$, where "$\vee$" is the "join"
operation. One can observe $e(E^k_n)=\binom{n-k}{2}+k^2$ and $E^k_n$ is not
Hamiltonian. As $E^k_n$ contains induced claws for $k\geq 2$, a natural
question is to characterize all 2-connected claw-free non-Hamiltonian graphs
with the largest possible number of edges. We answer this question completely
by proving a claw-free analog of Erd\H{o}s' theorem. Moreover, as byproducts,
we establish several tight spectral conditions for a 2-connected claw-free
graph to be Hamiltonian. Similar results for the traceability of connected
claw-free graphs are also obtained. Our tools include Ryj\'a\v{c}ek's claw-free
closure theory and Brousek's characterization of minimal 2-connected claw-free
non-Hamiltonian graphs.
| arxiv topic:math.CO |
arxiv_dataset-61621504.04295 | An incompressible state of a photo-excited electron gas
cond-mat.mes-hall
Two dimensional electrons in a magnetic field can form new states of matter
characterized by topological properties and strong electronic correlations as
displayed in the integer and fractional quantum Hall states. In these states
the electron liquid displays several spectacular characteristics which manifest
themselves in transport experiments with the quantization of the Hall
resistance and a vanishing longitudinal conductivity or in thermodynamic
equilibrium when the electron fluid becomes incompressible. Several experiments
have reported that dissipation-less transport can be achieved even at weak,
non-quantizing magnetic fields when the electrons absorb photons at specific
energies related to their cyclotron frequency. Compressibility measurements on
electrons on liquid helium demonstrate the formation of an incompressible
electronic state under these resonant excitation conditions.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-61631504.04395 | On short recurrence Krylov type methods for linear systems with many
right-hand sides
math.NA
Block and global Krylov subspace methods have been proposed as methods
adapted to the situation where one iteratively solves systems with the same
matrix and several right hand sides. These methods are advantageous, since they
allow to cast the major part of the arithmetic in terms of matrix-block vector
products, and since, in the block case, they take their iterates from a
potentially richer subspace. In this paper we consider the most established
Krylov subspace methods which rely on short recurrencies, i.e. BiCG, QMR and
BiCGStab. We propose modifications of their block variants which increase
numerical stability, thus at least partly curing a problem previously observed
by several authors. Moreover, we develop modifications of the "global" variants
which almost halve the number of matrix-vector multiplications. We present a
discussion as well as numerical evidence which both indicate that the
additional work present in the block methods can be substantial, and that the
new "economic" versions of the "global" BiCG and QMR method can be considered
as good alternatives to the BiCGStab variants.
| arxiv topic:math.NA |
arxiv_dataset-61641504.04495 | Bivariant $K$-theory with $R/Z$-coefficients and rho classes of unitary
representations
math.OA math.KT
We construct equivariant $KK$-theory with coefficients in $\mathbb{R}$ and
$\mathbb{R}/\mathbb{Z}$ as suitable inductive limits over ${\rm II}_1$-factors.
We show that the Kasparov product, together with its usual functorial
properties, extends to $KK$-theory with real coefficients.
Let $\Gamma$ be a group. We define a $\Gamma$-algebra $A$ to be
$K$-theoretically free and proper (KFP) if the group trace ${\bf tr}$ of
$\Gamma$ acts as the unit element in $KK^{\Gamma}_{\mathbb{R}}(A,A)$. We show
that free and proper $\Gamma$-algebras (in the sense of Kasparov) have the
(KFP) property. Moreover, if $\Gamma$ is torsion free and satisfies the
$KK^\Gamma$-form of the Baum-Connes conjecture, then every $\Gamma$-algebra
satisfies (KFP).
If $\alpha:\Gamma\to U_n$ is a unitary representation and $A$ satisfies
property (KFP), we construct in a canonical way a rho class $\rho_\alpha^A\in
KK_{\mathbb{R}/\mathbb{Z}}^{1,\Gamma}(A,A)$. This construction generalizes the
Atiyah-Patodi-Singer $K$-theory class with $\mathbb{R}/\mathbb{Z}$ coefficients
associated to $\alpha$.
| arxiv topic:math.OA math.KT |
arxiv_dataset-61651504.04595 | Random-projection ensemble classification
stat.ME
We introduce a very general method for high-dimensional classification, based
on careful combination of the results of applying an arbitrary base classifier
to random projections of the feature vectors into a lower-dimensional space. In
one special case that we study in detail, the random projections are divided
into disjoint groups, and within each group we select the projection yielding
the smallest estimate of the test error. Our random projection ensemble
classifier then aggregates the results of applying the base classifier on the
selected projections, with a data-driven voting threshold to determine the
final assignment. Our theoretical results elucidate the effect on performance
of increasing the number of projections. Moreover, under a boundary condition
implied by the sufficient dimension reduction assumption, we show that the test
excess risk of the random projection ensemble classifier can be controlled by
terms that do not depend on the original data dimension and a term that becomes
negligible as the number of projections increases. The classifier is also
compared empirically with several other popular high-dimensional classifiers
via an extensive simulation study, which reveals its excellent finite-sample
performance.
| arxiv topic:stat.ME |
arxiv_dataset-61661504.04695 | On Noether approach in the cosmological model with scalar and gauge
fields: symmetries and the selection rule
gr-qc astro-ph.CO
In this paper, based on the works of Capozziello et al., we have studied the
Noether symmetry approach in the cosmological model with scalar and gauge
fields proposed recently by Soda et al. The correct Noether symmetries and
related Lie algebra are given according to the minisuperspace quantum
cosmological model. The Wheeler-De Witt (WDW) equation is presented after
quantization and the classical trajectories are then obtained in the
semi-classical limit. The oscillating features of the wave function in the
cosmic evolution recover the so-called Hartle criterion, and the selection rule
in minisuperspace quantum cosmology is strengthened. Then we have realized now
the proposition that Noether symmetries select classical universes.
| arxiv topic:gr-qc astro-ph.CO |
arxiv_dataset-61671504.04795 | An approximation principle for congruence subgroups II: application to
the limit multiplicity problem
math.NT math.RT math.SP
This is a sequel to arXiv:1308.3604. We study applications to limit
multiplicity generalizing the results of arXiv:1208.2257.
| arxiv topic:math.NT math.RT math.SP |
arxiv_dataset-61681504.04895 | Luminosity and spin-period evolution of GX 304$-$1 during outbursts from
2009 to 2013 observed with the MAXI/GSC, RXTE/PCA, and Fermi/GBM
astro-ph.HE
A report is made on the luminosity and pulse-period evolution of the Be
binary X-ray pulsar, GX 304$-$1, during a series of outbursts from 2009 to 2013
observed by MAXI/GSC, RXTE/PCA, and Fermi/GBM. In total, twelve outbursts
repeated by $\sim$ 132.2 days were observed, which is consistent with the X-ray
periodicity of this object observed in the 1970s. These 12 outbursts, together
with those in the 1970s, were found to all recur with a well defined period of
132.189$\pm$0.02 d, which can be identified with the orbital period. The pulse
period at $\sim 275$ s, obtained from the RXTE/PCA and Fermi/GBM data,
apparently exhibited a periodic modulation synchronized with the outburst
period, suggesting the pulsar orbital motion, which is superposed on a secular
spin-up trend throughout the entire active phase. The observed pulse-period
changes were successfully represented by a model composed of the binary orbital
modulation and pulsar spin up caused by mass accretion through an accretion
disk. The orbital elements obtained from the best-fit model, including the
projected orbital semi-major axis $a_{\rm x}\sin i \simeq 500-600$ light-s and
an eccentricity $e \simeq 0.5$, are typical of Be binary X-ray pulsars.
| arxiv topic:astro-ph.HE |
arxiv_dataset-61691504.04995 | Forward Modeling of Reduced Power Spectra From Three-Dimensional k-Space
physics.space-ph astro-ph.EP astro-ph.IM physics.plasm-ph
We present results from a numerical forward model to evaluate one-dimensional
reduced power spectral densities (PSD) from arbitrary energy distributions in
$\mathbf{k}$-space. In this model, we can separately calculate the diagonal
elements of the spectral tensor for incompressible axisymmetric turbulence with
vanishing helicity. Given a critically balanced turbulent cascade with
$k_\|\sim k_\perp^\alpha$ and $\alpha<1$, we explore the implications on the
reduced PSD as a function of frequency. The spectra are obtained under the
assumption of Taylor's hypothesis. We further investigate the functional
dependence of the spectral index $\kappa$ on the field-to-flow angle $\theta$
between plasma flow and background magnetic field from MHD to electron kinetic
scales. We show that critically balanced turbulence asymptotically develops
toward $\theta$-independent spectra with a slope corresponding to the
perpendicular cascade. This occurs at a transition frequency
$f_{2D}(L,\alpha,\theta)$, which is analytically estimated and depends on outer
scale $L$, critical balance exponent $\alpha$ and field-to-flow angle $\theta$.
We discuss anisotropic damping terms acting on the $\mathbf{k}$-space
distribution of energy and their effects on the PSD. Further, we show that the
spectral anisotropies $\kappa(\theta)$ as found by Horbury et al. (2008) and
Chen et al. (2010) in the solar wind are in accordance with a damped critically
balanced cascade of kinetic Alfv\'en waves. We also model power spectra
obtained by von Papen et al. (2014) in Saturn's plasma sheet and find that the
change of spectral indices inside $9\,R_\mathrm{s}$ can be explained by damping
on electron scales.
| arxiv topic:physics.space-ph astro-ph.EP astro-ph.IM physics.plasm-ph |
arxiv_dataset-61701504.05095 | Hybrid Genetic Algorithm and Lasso Test Approach for Inferring Well
Supported Phylogenetic Trees based on Subsets of Chloroplastic Core Genes
cs.AI cs.NE q-bio.PE q-bio.QM
The amount of completely sequenced chloroplast genomes increases rapidly
every day, leading to the possibility to build large scale phylogenetic trees
of plant species. Considering a subset of close plant species defined according
to their chloroplasts, the phylogenetic tree that can be inferred by their core
genes is not necessarily well supported, due to the possible occurrence of
"problematic" genes (i.e., homoplasy, incomplete lineage sorting, horizontal
gene transfers, etc.) which may blur phylogenetic signal. However, a
trustworthy phylogenetic tree can still be obtained if the number of
problematic genes is low, the problem being to determine the largest subset of
core genes that produces the best supported tree. To discard problematic genes
and due to the overwhelming number of possible combinations, we propose an
hybrid approach that embeds both genetic algorithms and statistical tests.
Given a set of organisms, the result is a pipeline of many stages for the
production of well supported phylogenetic trees. The proposal has been applied
to different cases of plant families, leading to encouraging results for these
families.
| arxiv topic:cs.AI cs.NE q-bio.PE q-bio.QM |
arxiv_dataset-61711504.05195 | Electroweak Baryogenesis from Exotic Electroweak Symmetry Breaking
hep-ph
We investigate scenarios in which electroweak baryogenesis can occur during
an exotic stage of electroweak symmetry breaking in the early Universe. This
transition is driven by the expectation value of a new electroweak scalar
instead of the standard Higgs field. A later, second transition then takes the
system to the usual electroweak minimum, dominated by the Higgs, while
preserving the baryon asymmetry created in the first transition. We discuss the
general requirements for such a two-stage electroweak transition to be suitable
for electroweak baryogenesis and present a toy model that illustrates the
necessary ingredients. We then apply these results to construct an explicit
realization of this scenario within the inert two Higgs doublet model. Despite
decoupling the Higgs from the symmetry-breaking transition required for
electroweak baryogenesis, we find that this picture generically predicts new
light states that are accessible experimentally.
| arxiv topic:hep-ph |
arxiv_dataset-61721504.05295 | Structural phase transition and electronic structure evolution in
Ir1-xPtxTe2 studied by scanning tunneling microscopy
cond-mat.supr-con cond-mat.mtrl-sci
The IrTe2 transition metal dichalcogenide undergoes a series of structural
and electronic phase transitions when doped with Pt. The nature of each phase
and the mechanism of the phase transitions have attracted much attention. In
this paper, we report scanning tunneling microscopy and spectroscopy studies of
Pt doped IrTe2 with varied Pt contents. In pure IrTe2, we find that the ground
state has a 1/6 superstructure, and the electronic structure is inconsistent
with Fermi surface nesting induced charge density wave order. Upon Pt doping,
the crystal structure changes to a 1/5 superstructure and then to a
quasi-periodic hexagonal phase. First principles calculations show that the
superstructures and electronic structures are determined by the global chemical
strain and local impurity states that can be tuned systematically by Pt doping.
| arxiv topic:cond-mat.supr-con cond-mat.mtrl-sci |
arxiv_dataset-61731504.05395 | The dual boundary complex of the $SL_2$ character variety of a punctured
sphere
math.AG
Suppose $C_1,\ldots , C_k$ are generic conjugacy classes in $SL_2({\mathbb
C})$. Consider the character variety of local systems on ${\mathbb P}^1-\{
y_1,\ldots , y_k\}$ whose monodromy transformations around the punctures $y_i$
are in the respective conjugacy classes $C_i$. We show that the dual boundary
complex of this character variety is homotopy equivalent to a sphere of
dimension $2(k-3)-1$.
| arxiv topic:math.AG |
arxiv_dataset-61741504.05495 | Graphene wrinkling induced by monodisperse nanoparticles: facile control
and quantification
cond-mat.mes-hall
Controlled wrinkling of single-layer graphene (1-LG) at nanometer scale was
achieved by introducing monodisperse nanoparticles (NPs), with size comparable
to the strain coherence length, underneath the 1-LG. Typical fingerprint of the
delaminated fraction of 1-LG is identified as substantial contribution to the
principal Raman modes of the 1-LG. Correlation analysis of the Raman shift of
the modes clearly resolved the 1-LG in contact and delaminated from the
substrate, respectively. Intensity of Raman features of the delaminated 1-LG
increases linearly with the amount of the wrinkles, determined by advanced
processing of atomic force microscopy data. Our study thus offers universal
approach for both fine tuning and facile quantification of the graphene
topography up to ~ 60% of wrinkling.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-61751504.05595 | Unveiling the nature of the gamma-ray emitting AGN PKS 0521-36
astro-ph.HE
PKS 0521-36 is an Active Galactic Nucleus (AGN) with uncertain
classification. We investigate the properties of this source from radio to
gamma rays. The broad emission lines in the optical and UV bands and steep
radio spectrum indicate a possible classification as an intermediate object
between broad-line radio galaxies (BLRG) and steep spectrum radio quasars
(SSRQ). On pc-scales PKS 0521-36 shows a knotty structure similar to misaligned
AGN. The core dominance and the gamma-ray properties are similar to those
estimated for other SSRQ and BLRG detected in gamma rays, suggesting an
intermediate viewing angle with respect to the observer. In this context the
flaring activity detected from this source by Fermi-LAT between 2010 June and
2012 February is very intriguing. We discuss the gamma-ray emission of this
source in the framework of the structured jet scenario, comparing the spectral
energy distribution (SED) of the flaring state in 2010 June with that of a low
state. We present three alternative models corresponding to three different
choices of the viewing angles theta_v = 6, 15, and 20 deg. We obtain a good fit
for the the first two cases, but the SED obtained with theta_v = 15 deg if
observed at a small angle does not resemble that of a typical blazar since the
synchrotron emission should dominate by a large factor (about 100) the inverse
Compton component. This suggests that a viewing angle between 6 and 15 deg is
preferred, with the rapid variability observed during gamma-ray flares
favouring a smaller angle. However, we cannot rule out that PKS 0521-36 is the
misaligned counterpart of a synchrotron-dominated blazar.
| arxiv topic:astro-ph.HE |
arxiv_dataset-61761504.05695 | Graphene-based perfect optical absorbers harnessing guided mode
resonances
physics.optics
We numerically and experimentally investigate graphene-based optical
absorbers that exploit guided mode resonances (GMRs) achieving perfect
absorption over a bandwidth of few nanometers (over the visible and
near-infrared ranges) with a 40-fold increase of the monolayer graphene
absorption. We analyze the influence of the geometrical parameters on the
absorption rate and the angular response for oblique incidence. Finally, we
experimentally verify the theoretical predictions in a one-dimensional,
dielectric grating and placing it near either a metallic or a dielectric
mirror.
| arxiv topic:physics.optics |
arxiv_dataset-61771504.05795 | Gromov meets Phylogenetics - new Animals for the Zoo of Biocomputable
Metrics on Tree Space
math.MG math.CO
We present a new class of metrics for unrooted phylogenetic $X$-trees derived
from the Gromov-Hausdorff distance for (compact) metric spaces. These metrics
can be efficiently computed by linear or quadratic programming. They are robust
under NNI-operations, too. The local behavior of the metrics shows that they
are different from any formerly introduced metrics. The performance of the
metrics is briefly analised on random weighted and unweighted trees as well as
random caterpillars.
| arxiv topic:math.MG math.CO |
arxiv_dataset-61781504.05895 | Semantic Enrichment of Mobile Phone Data Records Using Background
Knowledge
cs.AI cs.IT math.IT
Every day, billions of mobile network events (i.e. CDRs) are generated by
cellular phone operator companies. Latent in this data are inspiring insights
about human actions and behaviors, the discovery of which is important because
context-aware applications and services hold the key to user-driven,
intelligent services, which can enhance our everyday lives such as social and
economic development, urban planning, and health prevention. The major
challenge in this area is that interpreting such a big stream of data requires
a deep understanding of mobile network events' context through available
background knowledge. This article addresses the issues in context awareness
given heterogeneous and uncertain data of mobile network events missing
reliable information on the context of this activity. The contribution of this
research is a model from a combination of logical and statistical reasoning
standpoints for enabling human activity inference in qualitative terms from
open geographical data that aimed at improving the quality of human behaviors
recognition tasks from CDRs. We use open geographical data, Openstreetmap
(OSM), as a proxy for predicting the content of human activity in the area. The
user study performed in Trento shows that predicted human activities (top
level) match the survey data with around 93% overall accuracy. The extensive
validation for predicting a more specific economic type of human activity
performed in Barcelona, by employing credit card transaction data. The analysis
identifies that appropriately normalized data on points of interest (POI) is a
good proxy for predicting human economical activities, with 84% accuracy on
average. So the model is proven to be efficient for predicting the context of
human activity, when its total level could be efficiently observed from cell
phone data records, missing contextual information however.
| arxiv topic:cs.AI cs.IT math.IT |
arxiv_dataset-61791504.05995 | Natural Deduction for the Sheffer Stroke and Peirce's Arrow (And Any
Other Truth-Functional Connective)
math.LO
Methods available for the axiomatization of arbitrary finite-valued logics
can be applied to obtain sound and complete intelim rules for all
truth-functional connectives of classical logic including the Sheffer stroke
(NAND) and Peirce's arrow (NOR). The restriction to a single conclusion in
standard systems of natural deduction requires the introduction of additional
rules to make the resulting systems complete; these rules are nevertheless
still simple and correspond straightforwardly to the classical absurdity rule.
Omitting these rules results in systems for intuitionistic versions of the
connectives in question.
| arxiv topic:math.LO |
arxiv_dataset-61801504.06095 | On some characterizations of strong power graphs of finite groups
math.CO
Let $ G $ be a finite group of order $ n$. The strong power graph
$\mathcal{P}_s(G) $ of $G$ is the undirected graph whose vertices are the
elements of $G$ such that two distinct vertices $a$ and $b$ are adjacent if
$a^{{m}_1}$=$b^{{m}_2}$ for some positive integers ${m}_1 ,{m}_2 < n$. In this
article we classify all groups $G$ for which $\mathcal{P}_s(G)$ is line graph
and Caley graph. Spectrum and permanent of the Laplacian matrix of the strong
power graph $\mathcal{P}_s(G)$ are found for any finite group $G$.
| arxiv topic:math.CO |
arxiv_dataset-61811504.06195 | Influence of localised smooth steps on the instability of a boundary
layer
physics.flu-dyn
We consider a smooth forward facing step defined by the Gauss error function
of height 4-30\% and four times the width of the local boundary layer thickness
$\delta_{99}$. The boundary layer flow over a smooth forward-facing stepped
plate is studied with particular emphasis on stabilisation and destabilisation
of the Tollmien-Schlichting (TS) waves and subsequently on transition. The
interaction between TS waves at a range of frequencies and a base flow over a
single/two forward facing smooth steps is conducted by linear analysis. The
results indicate that for a high frequency TS wave, the amplitude of the TS
wave is attenuated in the unstable regime of the neutral stability curve
corresponding to a flat plate boundary layer. Furthermore, it is observed that
two smooth forward facing steps lead to a more acute reduction of the amplitude
of the TS wave. When the height of a step is increased to more than 20\% of the
local boundary layer thickness for a fixed width parameter, the TS wave is
amplified and thereby a destabilisation effect is introduced. Therefore,
stabilisation or destabilisation effect of a smooth step is typically dependent
on its shape parameters. To validate the results of the linear stability
analysis, where a high-frequency TS wave is damped by the forward facing smooth
steps direct numerical simulation (DNS) is performed. The results of the DNS
correlate favorably with the linear analysis and show that for the investigated
high frequency TS wave, the K-type transition process is altered whereas the
onset of the H-type transition is postponed. The results of the DNS suggest
that for a high-frequency perturbation $\mathcal{F}=150$ and in the absence of
other external perturbations, two forward facing steps of height 5\% and 12\%
of the boundary layer thickness delayed H-type transition scenario and
completely suppresses it for the K-type transition.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-61821504.06295 | Quantum-corrected self-dual black hole entropy in tunneling formalism
with GUP
hep-th gr-qc
In this paper we focus on the Hamilton-Jacobi method to determine the entropy
of a self-dual black hole by using linear and quadratic GUPs(generalized
uncertainty principles). We have obtained the Bekenstein-Hawking entropy of
self-dual black holes and its quantum corrections that are logarithm and also
of several other types.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-61831504.06395 | Resource Allocation with Reverse Pricing for Communication Networks
cs.NI
Reverse pricing has been recognized as an effective tool to handle demand
uncertainty in the travel industry (e.g., airlines and hotels). To investigate
its viability for communication networks, we study the practical limitations of
(operator-driven) time-dependent pricing that has been recently introduced,
taking into account demand uncertainty. Compared to (operator-driven)
time-dependent pricing, we show that the proposed pricing scheme can achieve
"triple-win" solutions: an increase in the total average revenue of the
operator; higher average resource utilization efficiency; and an increment in
the total average payoff of the users. Our findings provide a new outlook on
resource allocation, and design guidelines for adopting the reverse pricing
scheme.
| arxiv topic:cs.NI |
arxiv_dataset-61841504.06495 | Systematic Coarse-Graining in Nucleation Theory
nucl-th
In this work we show that the standard method to obtain nucleation
rate-predictions with the aid of atomistic Monte-Carlo simulations leads to
nucleation rate predictions that deviate $3-5$ orders of magnitude from the
recent brute-force molecular dynamics simulations [J. Diemand, R. Ang\'{e}lil,
K. K. Tanaka, and H. Tanaka, J. Chem. Phys. \textbf{139}, 074309 (2013)]
conducted in the experimental accessible supersaturation regime for
Lennard-Jones argon. We argue that this is due to the truncated state space
literature mostly relies on, where the number of atoms in a nucleus is
considered the only relevant order parameter. We here formulate the
nonequilibrium statistical mechanics of nucleation in an extended state space,
where the internal energy and momentum of the nuclei is additionally
incorporated. We show that the extended model explains the lack in agreement
between the molecular dynamics simulations by Diemand et al.\ and the truncated
state space. We demonstrate additional benefits of using the extended state
space; in particular, the definition of a nucleus temperature arrises very
naturally and can be shown without further approximation to obey the
fluctuation law of McGraw and Laviolette. In addition, we illustrate that our
theory conveniently allows to extend existing theories to richer sets of order
parameters.
| arxiv topic:nucl-th |
arxiv_dataset-61851504.06595 | Positive Maps and Separable Matrices
math.OC
A linear map between real symmetric matrix spaces is positive if all positive
semidefinite matrices are mapped to positive semidefinite ones. A real
symmetric matrix is separable if it can be written as a summation of Kronecker
products of positive semidefinite matrices. This paper studies how to check if
a linear map is positive or not and how to check if a matrix is separable or
not. We propose numerical algorithms, based on Lasserre type semidefinite
relaxations, for solving such questions. To check the positivity of a linear
map, we construct a hierarchy of semidefinite relaxations for minimizing the
associated bi-quadratic forms over the unit spheres. We show that the
positivity can be detected by solving a finite number of such semidefinite
relaxations. To check the separability of a matrix, we construct a hierarchy of
semidefinite relaxations. If it is not separable, we can get a mathematical
certificate for that; if it is, we can get a decomposition for the
separability.
| arxiv topic:math.OC |
arxiv_dataset-61861504.06695 | Top Quark Anomalous Electromagnetic Couplings in Photon-Photon
Scattering at the LHC
hep-ph
The capability of the LHC to study the electromagnetic dipole moments of the
top quark is discussed. In particular, the process $pp\to p\gamma\gamma p\to
pt\bar{t}p$, which is supposed to be tagged by the forward/backward detectors
at the LHC experiments, is used to explore the top quark electric and magnetic
moments. We perform analytical calculations and then a numerical analysis on
the sensitivity of the total cross section of the top quark pair production in
$\gamma\gamma$ scattering at the LHC to the anomalous top quark couplings with
photon. It is shown that improvements in the bounds on the electromagnetic
dipole moments of the top quark can be achieved in this channel in comparison
with the constraints from the former studies.
| arxiv topic:hep-ph |
arxiv_dataset-61871504.06795 | Equidistribution for higher-rank Abelian actions on Heisenberg
nilmanifolds
math.DS
We prove quantitative equidistribution results for actions of Abelian
subgroups of the $2g+1$ dimensional Heisenberg group acting on compact
$2g+1$-dimensional homogeneous nilmanifolds. The results are based on the study
of the $C^\infty$-cohomology of the action of such groups, on tame estimates of
the associated cohomological equations and on a renormalisation method
initially applied by Forni to surface flows and by Forni and the second author
to other parabolic flows. As an application we obtain bounds for finite Theta
sums defined by real quadratic forms in $g$ variables, generalizing the
classical results of Hardy and Littlewood \cite{MR1555099, MR1555214} and the
optimal result of Fiedler, Jurkat and K\"orner \cite{MR0563894} to higher
dimension.
| arxiv topic:math.DS |
arxiv_dataset-61881504.06895 | Single-photon nonlinear optics with a quantum dot in a waveguide
quant-ph physics.optics
Strong nonlinear interactions between photons enable logic operations for
both classical and quantum-information technology. Unfortunately, nonlinear
interactions are usually feeble and therefore all-optical logic gates tend to
be inefficient. A quantum emitter deterministically coupled to a propagating
mode fundamentally changes the situation, since each photon inevitably
interacts with the emitter, and highly correlated many-photon states may be
created . Here we show that a single quantum dot in a photonic-crystal
waveguide can be utilized as a giant nonlinearity sensitive at the
single-photon level. The nonlinear response is revealed from the intensity and
quantum statistics of the scattered photons, and contains contributions from an
entangled photon-photon bound state. The quantum nonlinearity will find
immediate applications for deterministic Bell-state measurements and
single-photon transistors and paves the way to scalable waveguide-based
photonic quantum-computing architectures.
| arxiv topic:quant-ph physics.optics |
arxiv_dataset-61891504.06995 | Emergent phenomena in multicomponent superconductivity: an introduction
to the focus issue
cond-mat.supr-con cond-mat.mes-hall cond-mat.str-el
Multicomponent superconductivity is a novel quantum phenomenon in many
different superconducting materials, such as multiband ones in which different
superconducting gaps open in different Fermi surfaces, films engineered at the
atomic scale to enter the quantum confined regime, multilayers, two-dimensional
electron gases at the oxide interfaces, and complex materials in which
different electronic orbitals or different carriers participate in the
formation of the superconducting condensate. In all these systems the increased
number of degrees of freedom of the multicomponent superconducting
wave-function allows for emergent quantum effects that are otherwise
unattainable in single-component superconductors. In this editorial paper we
introduce the present focus issue, exploring the complex but fascinating
physics of multicomponent superconductivity.
| arxiv topic:cond-mat.supr-con cond-mat.mes-hall cond-mat.str-el |
arxiv_dataset-61901504.07095 | Structure of conformal metrics on $\mathbb{R}^n$ with constant
$Q$-curvature
math.AP math.DG
In this article we study the nonlocal equation \begin{align}
(-\Delta)^{\frac{n}{2}}u=(n-1)!e^{nu}\quad \text{in $\mathbb{R}^n$},
\quad\int_{\mathbb{R}^n}e^{nu}dx<\infty, \notag \end{align} which arises in the
conformal geometry. Inspired by the previous work of C. S. Lin and L.
Martinazzi in even dimension and T. Jin, A. Maalaoui, L. Martinazzi, J. Xiong
in dimension three we classify all solutions to the above equation in terms of
their behavior at infinity.
| arxiv topic:math.AP math.DG |
arxiv_dataset-61911504.07195 | Energy Spread of the Proton Beam in the Fermilab Booster at its
Injection Energy
physics.acc-ph
We have measured the total energy spread (99 persent energy spread) of the
Booster beam at its injection energy of 400 MeV by three different methods - 1)
creating a notch of about 40 nsec wide in the beam immediately after multiple
turn injection and measuring the slippage time required for high and low
momentum particles for a grazing touch in line-charge distribution, 2)
injecting partial turn beam and letting it to debunch, and 3) comparing the
beam profile monitor data with predictions from MAD simulations for the 400 MeV
injection beam line. The measurements are repeated under varieties of
conditions of RF systems in the ring and in the beam transfer line.
| arxiv topic:physics.acc-ph |
arxiv_dataset-61921504.07295 | Document Classification by Inversion of Distributed Language
Representations
cs.CL cs.IR stat.AP
There have been many recent advances in the structure and measurement of
distributed language models: those that map from words to a vector-space that
is rich in information about word choice and composition. This vector-space is
the distributed language representation. The goal of this note is to point out
that any distributed representation can be turned into a classifier through
inversion via Bayes rule. The approach is simple and modular, in that it will
work with any language representation whose training can be formulated as
optimizing a probability model. In our application to 2 million sentences from
Yelp reviews, we also find that it performs as well as or better than complex
purpose-built algorithms.
| arxiv topic:cs.CL cs.IR stat.AP |
arxiv_dataset-61931504.07395 | Lexical Translation Model Using a Deep Neural Network Architecture
cs.CL cs.LG cs.NE
In this paper we combine the advantages of a model using global source
sentence contexts, the Discriminative Word Lexicon, and neural networks. By
using deep neural networks instead of the linear maximum entropy model in the
Discriminative Word Lexicon models, we are able to leverage dependencies
between different source words due to the non-linearity. Furthermore, the
models for different target words can share parameters and therefore data
sparsity problems are effectively reduced.
By using this approach in a state-of-the-art translation system, we can
improve the performance by up to 0.5 BLEU points for three different language
pairs on the TED translation task.
| arxiv topic:cs.CL cs.LG cs.NE |
arxiv_dataset-61941504.07495 | Decode-Forward Transmission for the Two-Way Relay Channels
cs.IT math.IT
We propose composite decode-forward (DF) schemes for the two-way relay
channel in both the full- and half-duplex modes by combining coherent relaying,
independent relaying and partial relaying strategies. For the full-duplex mode,
the relay partially decodes each user's information in each block and forwards
this partial information coherently with the source user to the destination
user in the next block as in block Markov coding. In addition, the relay
independently broadcasts a binning index of both users' decoded information
parts in the next block as in independent network coding. Each technique has a
different impact on the relay power usage and the rate region. We further
analyze in detail the independent partial DF scheme and derive in closed-form
link regimes when this scheme achieves a strictly larger rate region than just
time-sharing between its constituent techniques, direct transmission and
independent DF relaying, and when it reduces to a simpler scheme. For the
half-duplex mode, we propose a 6-phase time-division scheme that incorporates
all considered relaying techniques and uses joint decoding simultaneously over
all receiving phases. Numerical results show significant rate gains over
existing DF schemes, obtained by performing link adaptation of the composite
scheme based on the identified link regimes.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-61951504.07595 | nCk sequences and their difference sequences
cs.DS
A nCk sequence is a sequence of n-bit numbers with k bits set. Given such a
sequence C, the difference sequence D of C is subject to certain regularities
that make it possible to generate D in 2|C| time, and, hence, to generate C in
3|C| time.
| arxiv topic:cs.DS |
arxiv_dataset-61961504.07695 | Identification of Globular Cluster Stars in RAVE data I: Application to
Stellar Parameter Calibration
astro-ph.GA
We present the identification of potential members of nearby Galactic
globular clusters using radial velocities from the RAdial Velocity Experiment
Data Release 4 (RAVE-DR4) survey database. Our identifications are based on
three globular clusters -- NGC 3201, NGC 5139 ($\omega$ Cen) and NGC 362 -- all
of which are shown to have |RV|>100 km/s. The identification of globular
cluster stars in RAVE DR4 data offers a unique opportunity to test the
precision and accuracy of the stellar parameters determined with the currently
available Stellar Parameter Pipelines (SPPs) used in the survey, as globular
clusters are ideal testbeds for the validation of stellar atmospheric
parameters, abundances, distances and ages. For both NGC 3201 and $\omega$ Cen,
there is compelling evidence for numerous members (> 10) in the RAVE database;
in the case of NGC 362 the evidence is more ambiguous, and there may be
significant foreground and/or background contamination in our
kinematically-selected sample. A comparison of the RAVE-derived stellar
parameters and abundances with published values for each cluster and with BASTI
isochrones for ages and metallicities from the literature reveals overall good
agreement, with the exception of the apparent underestimation of surface
gravities for giants, in particular for the most metal-poor stars. Moreover, if
the selected members are part of the main body of each cluster our results
would also suggest that the distances from Binney et al. 2013, where only
isochrones more metal-rich than -0.9 dex were used, are typically
underestimated by ~ 40% with respect to the published distances for the
clusters, while the distances from Zwitter et al. 2010 show stars ranging from
1 to ~ 6.5 kpc -- with indications of a trend toward higher distances at lower
metallicities -- for the three clusters analysed in this study.
| arxiv topic:astro-ph.GA |
arxiv_dataset-61971504.07795 | An automated multiscale ensemble simulation approach for vascular blood
flow
cs.DC cs.CE
Cerebrovascular diseases such as brain aneurysms are a primary cause of adult
disability. The flow dynamics in brain arteries, both during periods of rest
and increased activity, are known to be a major factor in the risk of aneurysm
formation and rupture. The precise relation is however still an open field of
investigation. We present an automated ensemble simulation method for modelling
cerebrovascular blood flow under a range of flow regimes. By automatically
constructing and performing an ensemble of multiscale simulations, where we
unidirectionally couple a 1D solver with a 3D lattice-Boltzmann code, we are
able to model the blood flow in a patient artery over a range of flow regimes.
We apply the method to a model of a middle cerebral artery, and find that this
approach helps us to fine-tune our modelling techniques, and opens up new ways
to investigate cerebrovascular flow properties.
| arxiv topic:cs.DC cs.CE |
arxiv_dataset-61981504.07895 | String gravitational equations with Hermitian structure
hep-th
We consider a string model at one-loop related to a $\sigma$-model whose
antisymmetric tensor field is constructed as complex structure on the
background manifold, specially on a manifold $R\times N$ where $N$ is a complex
manifold. As an example, we consider a homogeneous anisotropic
$(1+4)$-dimensional $\sigma$-model where space part of the background is a
$4$-dimensional complex manifold. By solving the related one-loop
$\beta$-functions we obtain a static solution so that by reduction of this
solution to $(1+3)$-dimension we obtain a static solution of Einstein equation
where the matter sector is effectively interpreted as an inhomogeneous,
anisotropic and barotropic matter satisfying all the energy conditions.
Finally, the $T$-dual background of the solution is investigated and it is
shown that the duality transformation and reduction processes commute with each
other.
| arxiv topic:hep-th |
arxiv_dataset-61991504.07995 | An Empirically Derived Three-Dimensional Laplace Resonance in the Gliese
876 Planetary System
astro-ph.EP
We report constraints on the three-dimensional orbital architecture for all
four planets known to orbit the nearby M dwarf Gliese 876 based solely on
Doppler measurements and demanding long-term orbital stability. Our dataset
incorporates publicly available radial velocities taken with the ELODIE and
CORALIE spectrographs, HARPS, and Keck HIRES as well as previously unpublished
HIRES velocities. We first quantitatively assess the validity of the planets
thought to orbit GJ 876 by computing the Bayes factors for a variety of
different coplanar models using an importance sampling algorithm. We find that
a four-planet model is preferred over a three-planet model. Next, we apply a
Newtonian MCMC algorithm to perform a Bayesian analysis of the planet masses
and orbits using an n-body model in three-dimensional space. Based on the
radial velocities alone, we find that a 99% credible interval provides upper
limits on the mutual inclinations for the three resonant planets
($\Phi_{cb}<6.20^\circ$ for the "c" and "b" pair and $\Phi_{be}<28.5^\circ$ for
the "b" and "e" pair). Subsequent dynamical integrations of our posterior
sample find that the GJ 876 planets must be roughly coplanar
($\Phi_{cb}<2.60^\circ$ and $\Phi_{be}<7.87^\circ$), suggesting the amount of
planet-planet scattering in the system has been low. We investigate the
distribution of the respective resonant arguments of each planet pair and find
that at least one argument for each planet pair and the Laplace argument
librate. The libration amplitudes in our three-dimensional orbital model
supports the idea of the outer-three planets having undergone significant past
disk migration.
| arxiv topic:astro-ph.EP |
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