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arxiv_dataset-45001307.8272 | Discrete exact and quasi-resonances of Rossby/drift waves on $\b$-plane
with periodic boundary conditions
physics.flu-dyn
Analysis of resonance clustering in weakly nonlinear dispersive wave systems,
also called discrete wave turbulent systems, is a new methodology successfully
used in the last years for characterizing energy transport due to exact and
quasi-resonances. Quite recently this methodology has been used in the paper by
M. D. Bustamante, U. Hayat "Complete classification of discrete resonant
Rossby/drift wave triads on periodic domains", \cite{BH13}, in order to show
that resonance clustering is very sparse and quasi-resonances (that is,
resonances with small enough detuning) play major role in the energy transport
in this specific wave system. On the other hand, in the paper by M. Yamada, T.
Yoneda "Resonant interaction of Rossby waves in two-dimensional flow on
$\beta$-plane", \cite{YaYo13}, the same physical system is studied and a
mathematically rigorous theorem is proven: at high $\b$, the flow dynamics is
governed exclusively by resonant interactions. In our present paper we
demonstrate that this seeming contradiction between numerical results
\cite{BH13} and analytical results \cite{YaYo13} are due to some pitfalls in
numerical studies of exact and quasi-resonances presented in \cite{BH13}. We
also demonstrate that resonance clustering of drift waves on periodic
$\b$-plane differs substantially from characteristic resonance clustering in
other 3-wave systems: instead of a usual set of isolated triads and a few
bigger clusters, there exists \emph{no isolated triads} in this case. Resonant
triads are interconnected in a complicated way and the smallest cluster
consists of 6 connected triads.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-45011307.8372 | Helioseismology from SODISM and HMI Intensity Images
astro-ph.SR
Continuum intensity images from PICARD/SODISM and SDO/HMI covering a 209 days
period in 2011 are analyzed in order to extract mode parameters for spherical
harmonics up to $l=100$. SODISM helioseismology signal is affected by the low
orbit of PICARD and by important gaps and CCD persistence effects. SODISM
intensity signal has a lower signal to noise ratio and duty cycle than HMI and
less modes were successfully fitted over the same period. A comparison of the
rotation profiles obtained from both sets of continuum images shows however
that the results remain compatible within one standard deviation of HMI formal
errors.
| arxiv topic:astro-ph.SR |
arxiv_dataset-45021308.0025 | Higgs mass naturalness and scale invariance in the UV
hep-ph
It has been suggested that electroweak symmetry breaking in the Standard
Model may be natural if the Standard Model merges into a conformal field theory
(CFT) at short distances. In such a scenario the Higgs mass would be protected
from quantum corrections by the scale invariance of the CFT. In order for the
Standard Model to merge into a CFT at least one new ultraviolet (UV) scale is
required at which the couplings turn over from their usual Standard Model
running to the fixed point behavior. We argue that the Higgs mass is sensitive
to such a turn-over scale even if there are no associated massive particles and
the scale arises purely from dimensional transmutation. We demonstrate this
sensitivity to the turnover scale explicitly in toy models. Thus if scale
invariance is responsible for Higgs mass naturalness, then the transition to
CFT dynamics must occur near the TeV scale with observable consequences at
colliders. In addition, the UV fixed point theory in such a scenario must be
interacting because logarithmic running near a free fixed point constitutes
hard breaking of scale invariance and spoils the Higgs mass protection.
| arxiv topic:hep-ph |
arxiv_dataset-45031308.0125 | Recent RHIC in-situ coating technology developments
physics.acc-ph physics.ins-det
To rectify the problems of electron clouds observed in RHIC and unacceptable
ohmic heating for superconducting magnets that can limit future machine
upgrades, we started developing a robotic plasma deposition technique for
$in-situ$ coating of the RHIC 316LN stainless steel cold bore tubes based on
staged magnetrons mounted on a mobile mole for deposition of Cu followed by
amorphous carbon (a-C) coating. The Cu coating reduces wall resistivity, while
a-C has low SEY that suppresses electron cloud formation. Recent RF resistivity
computations indicate that 10 {\mu}m of Cu coating thickness is needed. But, Cu
coatings thicker than 2 {\mu}m can have grain structures that might have lower
SEY like gold black. A 15-cm Cu cathode magnetron was designed and fabricated,
after which, 30 cm long samples of RHIC cold bore tubes were coated with
various OFHC copper thicknesses; room temperature RF resistivity measured.
Rectangular stainless steel and SS discs were Cu coated. SEY of rectangular
samples were measured at room; and, SEY of a disc sample was measured at
cryogenic temperatures.
| arxiv topic:physics.acc-ph physics.ins-det |
arxiv_dataset-45041308.0225 | Engineering three-body interaction and Pfaffian states in circuit QED
systems
quant-ph cond-mat.str-el cond-mat.supr-con
We demonstrate a scheme to engineer the three-body interaction in circuit-QED
systems by tuning a fluxonium qubit. Connecting such qubits in a square lattice
and controlling the tunneling dynamics, in the form of a synthesized magnetic
field, for the photon-like excitations of the system, allows the implementation
of a parent Hamiltonian whose ground state is the Pfaffian wave function.
Furthermore, we show that the addition of the next-nearest neighbor tunneling
stabilizes the ground state, recovering the expected topological degeneracy
even for small lattices. Finally, we discuss the implementation of these ideas
with the current technology.
| arxiv topic:quant-ph cond-mat.str-el cond-mat.supr-con |
arxiv_dataset-45051308.0325 | Noether gauge symmetry for the Bianchi type I model in f(T) gravity
gr-qc
In this paper, we present the Noether symmetries of a class of the Bianchi
type I anisotropic model in the context of f(T) gravity. By solving the system
of equations obtained from the Noether symmetry condition, we obtain the form
of f(T) as a teleparallel form. This analysis shows that teleparallel gravity
has the maximum number of Noether symmetries. We derive the symmetry generators
and show that there are five kinds of symmetries, including time and scale
invariance under metric coefficients. We classify the symmetries and we obtain
the corresponding invariants.
| arxiv topic:gr-qc |
arxiv_dataset-45061308.0425 | A perturbation result for the $Q_{\ gamma}$ curvature problem on
$\mathbb{S}^n$
math.AP math.DG math.FA
We consider the problem of prescribing the $Q_{\ gamma}$ curvature on
$\mathbb{S}^n$. Using a perturbation method, we obtain existence results for
curvatures close to a positive constant.
| arxiv topic:math.AP math.DG math.FA |
arxiv_dataset-45071308.0525 | In vivo interactions between tungsten microneedles and peripheral nerves
cond-mat.soft physics.med-ph
Tungsten microneedles are currently used to insert neural electrodes into
living peripheral nerves. However, the biomechanics underlying these procedures
is not yet well characterized. For this reason, the aim of this work was to
model the interactions between these microneedles and living peripheral nerves.
A simple mathematical framework was especially provided to model both
compression of the external layer of the nerve (epineurium) and the
interactions resulting from penetration of the main shaft of the microneedle
inside the living nerves. The instantaneous Young's modulus, compression force,
the work needed to pierce the tissue, puncturing pressure, and the dynamic
friction coefficient between the tungsten microneedles and living nerves were
quantified starting from acute experiments, aiming to reproduce the physical
environment of real implantations. Indeed, a better knowledge of the
interactions between microneedles and peripheral nerves may be useful to
improve the effectiveness of these insertion techniques, and could represent a
key factor for designing robot-assisted procedures tailored for peripheral
nerve insertion.
| arxiv topic:cond-mat.soft physics.med-ph |
arxiv_dataset-45081308.0625 | TCP-Aware Backpressure Routing and Scheduling
cs.NI
In this work, we explore the performance of backpressure routing and
scheduling for TCP flows over wireless networks. TCP and backpressure are not
compatible due to a mismatch between the congestion control mechanism of TCP
and the queue size based routing and scheduling of the backpressure framework.
We propose a TCP-aware backpressure routing and scheduling that takes into
account the behavior of TCP flows. TCP-aware backpressure (i) provides
throughput optimality guarantees in the Lyapunov optimization framework, (ii)
gracefully combines TCP and backpressure without making any changes to the TCP
protocol, (iii) improves the throughput of TCP flows significantly, and (iv)
provides fairness across competing TCP flows.
| arxiv topic:cs.NI |
arxiv_dataset-45091308.0725 | A Rough Computing based Performance Evaluation Approach for Educational
Institutions
cs.CY cs.AI
Performance evaluation of various organizations especially educational
institutions is a very important area of research and needs to be cultivated
more. In this paper, we propose a performance evaluation for educational
institutions using rough set on fuzzy approximation spaces with ordering rules
and information entropy. In order to measure the performance of educational
institutions, we construct an evaluation index system. Rough set on fuzzy
approximation spaces with ordering is applied to explore the evaluation index
data of each level. Furthermore, the concept of information entropy is used to
determine the weighting coefficients of evaluation indexes. Also, we find the
most important indexes that influence the weighting coefficients. The proposed
approach is validated and shows the practical viability. Moreover, the proposed
approach can be applicable to any organizations.
| arxiv topic:cs.CY cs.AI |
arxiv_dataset-45101308.0825 | Growth and fragmentation of centimetre-sized dust aggregates: the
dependence on aggregate size and porosity
astro-ph.EP astro-ph.SR
We carry out three-dimensional Smoothed Particle Hydrodynamics simulations of
spherical homogeneous SiO2 dust aggregates to investigate how the mass and the
porosity of the aggregates affects their ability to survive an impact at
various different collision velocities (between 1 - 27.5m/s). We explore how
the threshold velocities for fragmentation vary with these parameters.
Crucially, we find that the porosity plays a part of utmost importance in
determining the outcome of collisions. In particular, we find that aggregates
with filling factors >37% are significantly weakened and that the velocity
regime in which the aggregates grow is reduced or even non-existent (instead,
the aggregates either rebound off each other or break apart). At filling
factors less than ~37% we find that more porous objects are weaker but not as
weak as highly compact objects with filling factors >37%. In addition we find
that (for a given aggregate density) collisions between very different mass
objects have higher threshold velocities than those between very similar mass
objects. We find that fragmentation velocities are higher than the typical
values of 1m/s and that growth can even occur for velocities as high as
27.5m/s. Therefore, while the growth of aggregates is more likely if collisions
between different sized objects occurs or if the aggregates are porous with
filling factor <37%, it may also be hindered if the aggregates become too
compact.
| arxiv topic:astro-ph.EP astro-ph.SR |
arxiv_dataset-45111308.0925 | Unveiling correlations between financial variables and topological
metrics of trading networks: Evidence from a stock and its warrant
q-fin.ST
Traders adopt different trading strategies to maximize their returns in
financial markets. These trading strategies not only results in specific
topological structures in trading networks, which connect the traders with the
pairwise buy-sell relationships, but also have potential impacts on market
dynamics. Here, we present a detailed analysis on how the market behaviors are
correlated with the structures of traders in trading networks based on audit
trail data for the Baosteel stock and its warrant at the transaction level from
22 August 2005 to 23 August 2006. In our investigation, we divide each trade
day into 48 time windows with a length of five minutes, construct a trading
network within each window, and obtain a time series of over 1,100 trading
networks. We find that there are strongly simultaneous correlations between the
topological metrics (including network centralization, assortative index, and
average path length) of trading networks that characterize the patterns of
order execution and the financial variables (including return, volatility,
intertrade duration, and trading volume) for the stock and its warrant. Our
analysis may shed new lights on how the microscopic interactions between
elements within complex system affect the system's performance.
| arxiv topic:q-fin.ST |
arxiv_dataset-45121308.1025 | Bohr Hamiltonian with deformation-dependent mass term for the Kratzer
potential
nucl-th
The Deformation Dependent Mass (DDM) Kratzer model is constructed by
considering the Kratzer potential in a Bohr Hamiltonian, in which the mass is
allowed to depend on the nuclear deformation, and solving it by using
techniques of supersymmetric quantum mechanics (SUSYQM), involving a deformed
shape invariance condition. Analytical expressions for spectra and wave
functions are derived for separable potentials in the cases of gamma-unstable
nuclei, axially symmetric prolate deformed nuclei, and triaxial nuclei,
implementing the usual approximations in each case. Spectra and B(E2)
transition rates are compared to experimental data. The dependence of the mass
on the deformation, dictated by SUSYQM for the potential used, moderates the
increase of the moment of inertia with deformation, removing a main drawback of
the model.
| arxiv topic:nucl-th |
arxiv_dataset-45131308.1125 | Creation of the inverse population in the $^{229}$Th ground-state
doublet
nucl-th physics.atom-ph
A new method for obtaining of inverse population between quadrupole sublevels
of the ground state $5/2^+(0.0)$ and the isomeric state $3/2^+(7.6$ eV) of the
$^{229}$Th nucleus in a dielectric crystal with a large band gap by means of
external source of the VUV radiation is proposed. The method is based on an
efficient depopulation of the upper sublevels of the ground state of $^{229}$Th
by resonant photons from narrowband laser or broader tunable free electron
laser. Sublevels of the isomeric state play the role of intermediate states. In
addition, we have considered a case of excitation of the isomeric state
(without creation of inverse population) by broadband source of light with the
anti-Stokes scattering. The proposed scheme of optical pumping results in (1)
inverse population of nuclear sublevels without using extremely low
temperatures, and (2) shows a new way for the creation of the gamma-ray laser
of optical range at the nuclear transition in $^{229}$Th (a) in crystals with
isovalent substitution of host ions (eg Si$^{4+}$ ions in the SiO$_2$ crystal
replaced by the $^{229}$Th$^{4+}$ ions) and (b) in crystals such as
Na$_2$ThF$_6$, where the substitution is not necessary.
| arxiv topic:nucl-th physics.atom-ph |
arxiv_dataset-45141308.1225 | Electron rescattering at metal nanotips induced by ultrashort laser
pulses
cond-mat.mes-hall
We theoretically investigate the interaction of moderate intensity
near-infrared few cycle laser pulses with nano-scale metal tips. Local field
enhancement in a nanometric region around the tip apex triggers coherent
electron emission on the nanometer length and femtosecond time scale. The
quantum dynamics at the surface are simulated with time-dependent density
functional theory (TDDFT) and interpreted based on the simple man's model. We
investigate the dependence of the emitted electron spectra on the laser
wavelength.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-45151308.1325 | On the conformal structure of the extremal Reissner-Nordstr\"om
spacetime
gr-qc
We analyse various conformal properties of the extremal Reissner-Nordstr\"om
spacetime. In particular, we obtain conformal representations of the
neighbourhoods of spatial infinity, timelike infinity and the cylindrical end
---the so-called cylinders at spatial infinity and at the horizon,
respectively--- which are regular with respect to the conformal Einstein field
equations and their associated initial data sets. We discuss possible
implications of these constructions for the propagation of test fields and
non-linear perturbations of the gravitational field close to the horizon.
| arxiv topic:gr-qc |
arxiv_dataset-45161308.1425 | Microwave control of the interaction between two optical photons
physics.atom-ph
A microwave field is used to control the interaction between pairs of optical
photons stored in highly excited collective states (Rydberg polaritons). We
show that strong dipole-dipole interactions induced by the microwave field
destroy the coherence of polariton modes with more than one Rydberg excitation.
Consequently single-polariton modes, which correspond to single stored photons,
are preferentially retrieved from the sample. Measurements of the photon
statistics of the retrieved light field also reveal non-trivial propagation
dynamics of the interacting polaritons.
| arxiv topic:physics.atom-ph |
arxiv_dataset-45171308.1525 | Composite Particles and the Szilard Engine
quant-ph
The Szilard engine is the simplest possible engine, composed only of one or
more particles in a box. The box is then immersed in a heat bath and
partitioned into two parts by a wall. It is known that in the cold temperature
limit, one may extract more work out of elementary boson than out of elementary
fermions. In this paper, we consider the amount of work that can be extracted
out of a system of composite particles -- particles which are composed of two
interacting elementary fermions of different species. We demonstrate that the
amount of work extracted is closely tied to the amount of entanglement within
the composite particles
| arxiv topic:quant-ph |
arxiv_dataset-45181308.1625 | Four families of Weyl group orbit functions of B_3 and C_3
math-ph math.MP
The properties of the four families of special functions of three real
variables, called here C-, S-, S^s- and S^l-functions, are studied. The S^s-
and S^l-functions are considered in all details required for their exploitation
in Fourier expansions of digital data, sampled on finite fragment of lattices
of any density and of the 3D symmetry imposed by the weight lattices of B_3 and
C_3 simple Lie algebras/groups. The continuous interpolations, which are
induced by the discrete expansions, are exemplified and compared for some model
functions.
| arxiv topic:math-ph math.MP |
arxiv_dataset-45191308.1725 | State Estimation over Sensor Networks with Correlated Wireless Fading
Channels
math.OC cs.IT cs.SY math.IT
Stochastic stability for centralized time-varying Kalman filtering over a
wireles ssensor network with correlated fading channels is studied. On their
route to the gateway, sensor packets, possibly aggregated with measurements
from several nodes, may be dropped because of fading links. To study this
situation, we introduce a network state process, which describes a finite set
of configurations of the radio environment. The network state characterizes the
channel gain distributions of the links, which are allowed to be correlated
between each other. Temporal correlations of channel gains are modeled by
allowing the network state process to form a (semi-)Markov chain. We establish
sufficient conditions that ensure the Kalman filter to be exponentially
bounded. In the one-sensor case, this new stability condition is shown to
include previous results obtained in the literature as special cases. The
results also hold when using power and bit-rate control policies, where the
transmission power and bit-rate of each node are nonlinear mapping of the
network state and channel gains.
| arxiv topic:math.OC cs.IT cs.SY math.IT |
arxiv_dataset-45201308.1825 | Higgs Boson Phenomenology in a Simple Model with Vector Resonances
hep-ph
In this paper we consider a simple scenario where the Higgs boson and two
vector resonances are supposed to arise from a new strong interacting sector.
We use the ATLAS measurements of the dijet spectrum to set limits on the masses
of the resonances. Additionally we compute the Higgs boson decay to two photons
and found, when compare to the Standard Model prediction, a small excess which
is compatible with ATLAS measurements. Finally we make prediction for
Higgs-strahlung processes for the LHC running at 14 TeV.
| arxiv topic:hep-ph |
arxiv_dataset-45211308.1925 | Calculation of the Autocorrelation Function of the Stochastic Single
Machine Infinite Bus System
physics.soc-ph nlin.CD
Critical slowing down (CSD) is the phenomenon in which a system recovers more
slowly from small perturbations. CSD, as evidenced by increasing signal
variance and autocorrelation, has been observed in many dynamical systems
approaching a critical transition, and thus can be a useful signal of proximity
to transition. In this paper, we derive autocorrelation functions for the state
variables of a stochastic single machine infinite bus system (SMIB). The
results show that both autocorrelation and variance increase as this system
approaches a saddle-node bifurcation. The autocorrelation functions help to
explain why CSD can be used as an indicator of proximity to criticality in
power systems revealing, for example, how nonlinearity in the SMIB system
causes these signs to appear.
| arxiv topic:physics.soc-ph nlin.CD |
arxiv_dataset-45221308.2025 | Electromagnetic Shower Properties in a Lead-Scintillator Sampling
Calorimeter
physics.ins-det hep-ex
The Collider Detector at Fermilab (CDF) is a general-purpose experimental
apparatus with an inner tracking detector for measuring charged particles,
surrounded by a calorimeter for measurements of electromagnetic and hadronic
showers. We describe a {\sc geant4} simulation and parameterization of the
response of the CDF central electromagnetic calorimeter (CEM) to incident
electrons and photons. The detector model consists of a detailed description of
the CEM geometry and material in the direction of the incident particle's
trajectory, and of the passive material between the tracker and the CEM. We use
{\sc geant4} to calculate the distributions of: the energy that leaks from the
back of the CEM, the energy fraction sampled by the scintillators, and the
energy dependence of the response. We parameterize these distributions to
accurately model electron and photon response and resolution in a custom
simulation for the measurement of the $W$ boson mass.
| arxiv topic:physics.ins-det hep-ex |
arxiv_dataset-45231308.2125 | Detection of antiferromagnetic ordering in heavily doped LaFeAsO1-xHx
pnictide superconductors using nuclear-magnetic-resonance techniques
cond-mat.supr-con
We studied double superconducting (SC) domes in LaFeAsO1-xHx by using 75As-
and 1H-nuclear magnetic resonance techniques, and unexpectedly discovered that
a new antiferromagnetic (AF) phase follows the double SC domes on further H
doping, forming a symmetric alignment of AF and SC phases in the electronic
phase diagram. We demonstrated that the new AF ordering originates from the
nesting between electron pockets, unlike the nesting between electron and hole
pockets as seen in the majority of undoped pnictides. The new AF ordering is
derived from the features common to high-Tc pnictides: however, it has not been
reported so far for other high-Tc pnictides because of their poor electron
doping capability.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-45241308.2225 | Probing the nature of the Higgs-gluon coupling
hep-ph
One and two-jet observables of dimension-7 Higgs-gluon coupling operators are
studied as probes of possible deviations from the top-loop induced gluon-Higgs
coupling. We discuss the case of both a scalar as well as a pseudo-scalar Higgs
boson and show that higher order operators can give visible deviations from
Standard Model distribution shapes.
| arxiv topic:hep-ph |
arxiv_dataset-45251308.2325 | CESR Test Accelerator
physics.acc-ph
The Cornell Electron Storage Ring (CESR) was reconfigured in 2008 as a test
accelerator to investigate the physics of ultra-low emittance damping rings.
During the approximately 40 days/year available for dedicated operation as a
test accelerator, specialized instrumentation is used to measure growth and
mitigation of the electron cloud, emittance growth due to electron cloud,
intra-beam scattering, and ions, and single and multi-bunch instabilities
generated by collective effects. The flexibility of the CESR guide field optics
and the integration of accelerator modeling codes with the control system have
made possible an extraordinary range of experiments. Findings at CesrTA with
respect to electron cloud effects, emittance tuning techniques, and beam
instrumentation for measuring electron cloud, beam sizes, and beam positions
are the basis for much of the design of the ILC damping rings as documented in
the ILC-Technical Design Report. The program has allowed the Cornell group to
cultivate the kind of talent and expertise that will be absolutely essential to
the final engineering design, and commissioning of the damping rings for a
linear collider.
| arxiv topic:physics.acc-ph |
arxiv_dataset-45261308.2425 | Proton Kinetic Effects and Turbulent Energy Cascade Rate in the Solar
Wind
physics.space-ph physics.plasm-ph
The first observed connection between kinetic instabilities driven by proton
temperature anisotropy and estimated energy cascade rates in the turbulent
solar wind is reported using measurements from the Wind spacecraft at 1 AU. We
find enhanced cascade rates are concentrated along the boundaries of the
($\beta_{\parallel}$, $T_{\perp}/T_{\parallel}$)-plane, which includes regions
theoretically unstable to the mirror and firehose instabilities. A strong
correlation is observed between the estimated cascade rate and kinetic effects
such as temperature anisotropy and plasma heating, resulting in protons 5-6
times hotter and 70-90% more anisotropic than under typical isotropic plasma
conditions. These results offer new insights into kinetic processes in a
turbulent regime.
| arxiv topic:physics.space-ph physics.plasm-ph |
arxiv_dataset-45271308.2525 | Picard numbers of quintic surfaces
math.AG math.NT
We solve the Picard number problem for complex quintic surfaces by proving
that every number between 1 and 45 occurs as Picard number of a quintic surface
over the rationals. Our main technique consists in arithmetic deformations of
Delsarte surfaces, but we also use K3 surfaces and wild automorphisms.
| arxiv topic:math.AG math.NT |
arxiv_dataset-45281308.2625 | Sufficient Conditions for Feasibility and Optimality of Real-Time
Optimization Schemes - II. Implementation Issues
math.OC
The idea of iterative process optimization based on collected output
measurements, or "real-time optimization" (RTO), has gained much prominence in
recent decades, with many RTO algorithms being proposed, researched, and
developed. While the essential goal of these schemes is to drive the process to
its true optimal conditions without violating any safety-critical, or "hard",
constraints, no generalized, unified approach for guaranteeing this behavior
exists. In this two-part paper, we propose an implementable set of conditions
that can enforce these properties for any RTO algorithm. This second part
examines the practical side of the sufficient conditions for feasibility and
optimality (SCFO) proposed in the first and focuses on how they may be enforced
in real application, where much of the knowledge required for the conceptual
SCFO is unavailable. Methods for improving convergence speed are also
considered.
| arxiv topic:math.OC |
arxiv_dataset-45291308.2725 | Adaptive and Iterative Multi-Branch MMSE Decision Feedback Detection
Algorithms for MIMO Systems
cs.IT math.IT
In this work, decision feedback (DF) detection algorithms based on multiple
processing branches for multi-input multi-output (MIMO) spatial multiplexing
systems are proposed. The proposed detector employs multiple cancellation
branches with receive filters that are obtained from a common matrix inverse
and achieves a performance close to the maximum likelihood detector (MLD).
Constrained minimum mean-squared error (MMSE) receive filters designed with
constraints on the shape and magnitude of the feedback filters for the
multi-branch MMSE DF (MB-MMSE-DF) receivers are presented. An adaptive
implementation of the proposed MB-MMSE-DF detector is developed along with a
recursive least squares-type algorithm for estimating the parameters of the
receive filters when the channel is time-varying. A soft-output version of the
MB-MMSE-DF detector is also proposed as a component of an iterative detection
and decoding receiver structure. A computational complexity analysis shows that
the MB-MMSE-DF detector does not require a significant additional complexity
over the conventional MMSE-DF detector, whereas a diversity analysis discusses
the diversity order achieved by the MB-MMSE-DF detector. Simulation results
show that the MB-MMSE-DF detector achieves a performance superior to existing
suboptimal detectors and close to the MLD, while requiring significantly lower
complexity.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-45301308.2825 | Approach to Equilibrium of a Nondegenerate Quantum System: Decay of
Oscillations and Detailed Balance as Separate Effects of a Reservoir
cond-mat.stat-mech
The approach to equilibrium of a nondegenerate quantum system involves the
damping of microscopic population oscillations, and, additionally, the bringing
about of detailed balance, i.e. the achievement of the correct Boltzmann
factors relating the populations. These two are separate effects of interaction
with a reservoir. One stems from the randomization of phases and the other from
phase space considerations. Even the meaning of the word `phase' differs
drastically in the two instances in which it appears in the previous statement.
In the first case it normally refers to quantum phases whereas in the second it
describes the multiplicity of reservoir states that corresponds to each system
state. The generalized master equation theory for the time evolution of such
systems is here developed in a transparent manner and both effects of reservoir
interactions are addressed in a unified fashion. The formalism is illustrated
in simple cases including in the standard spin-boson situation wherein a
quantum dimer is in interaction with a bath consisting of harmonic oscillators.
The theory has been constructed for application in energy transfer in molecular
aggregates and in photosynthetic reaction centers.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-45311308.2925 | Glueball and meson spectrum in large-N massless QCD
hep-th hep-lat hep-ph
We provide outstanding numerical evidence that in large-N massless QCD the
joint spectrum of the masses squared, for fixed integer spin s and unspecified
parity and charge conjugation, obeys exactly the following laws: m_k^2 =
(k+s/2) Lambda_QCD^2 for s even, m_k^2 = 2(k+s/2) Lambda_QCD^2 for s odd, k =
1,2,... for glueballs, and m_n^2 = 1/2 (n+s/2) Lambda_QCD^2, n = 0,1,... for
mesons. One of the striking features of these laws is that they imply that the
glueball and meson masses squared form exactly-linear Regge trajectories in the
large-N limit of massless QCD, all the way down to the low-lying states: A fact
unsuspected so far. The numerical evidence is based on lattice computations by
Meyer-Teper in SU(8) YM for glueballs, and by Bali et al. in SU(17) quenched
massless QCD for mesons, that we analyze systematically. The aforementioned
spectrum for spin-0 glueballs is implied by a Topological Field Theory
underlying the large-N limit of YM, whose glueball propagators satisfy as well
fundamental universal constraints arising from the asymptotic freedom and the
renormalization group. No other presently existing model meets both the
infrared spectrum and the ultraviolet constraints. We argue that some features
of the aforementioned spectrum of glueballs and mesons of any spin could be
explained by the existence of a Topological String Theory dual to the
Topological Field Theory.
| arxiv topic:hep-th hep-lat hep-ph |
arxiv_dataset-45321308.3025 | Effect of assessment error and private information on stern-judging in
indirect reciprocity
physics.soc-ph cs.SI q-bio.PE
Stern-judging is one of the best-known assessment rules in indirect
reciprocity. Indirect reciprocity is a fundamental mechanism for the evolution
of cooperation. It relies on mutual monitoring and assessments, i.e.,
individuals judge, following their own assessment rules, whether other
individuals are "good" or "bad" according to information on their past
behaviors. Among many assessment rules, stern-judging is known to provide
stable cooperation in a population, as observed when all members in the
population know all about others' behaviors (public information case) and when
the members never commit an assessment error. In this paper, the effect of
assessment error and private information on stern-judging is investigated. By
analyzing the image matrix, which describes who is good in the eyes of whom in
the population, we analytically show that private information and assessment
error cause the collapse of stern-judging: all individuals assess other
individuals as "good" at random with a probability of 1/2.
| arxiv topic:physics.soc-ph cs.SI q-bio.PE |
arxiv_dataset-45331308.3125 | Subrecoil cavity cooling towards degeneracy: A numerical study
quant-ph cond-mat.quant-gas
We present a detailed numerical analysis of the temperature limit and
timescale of cavity cooling of a dilute gas in the quantum regime for particles
and light. For a cavity with a linewidth smaller than the recoil frequency
efficient cooling towards quantum degeneracy is facilitated by applying a
tailored sequence of laser pulses transferring the particles towards lower
momenta. Two-particle Monte Carlo wave function simulations reveal strongly
improved cooling properties for a ring versus a standing-wave geometry.
Distinct quantum correlations and cooling limits for bosons and fermions
demonstrate quantum statistical effects. In particular, in ring cavities the
photon-mediated long-range interaction favours momentum-space pairing of
bosons, while fermion pairs exhibit anti-correlated or uncorrelated momenta.
The results are consistent with recent experiments and give encouraging
prospects to achieve sufficient conditions for the condensation of a wide class
of polarisable particles via cavity cooling.
| arxiv topic:quant-ph cond-mat.quant-gas |
arxiv_dataset-45341308.3225 | An interactive engine for multilingual video browsing using semantic
content
cs.MM cs.CV cs.IR
The amount of audio-visual information has increased dramatically with the
advent of High Speed Internet. Furthermore, technological advances in recent
years in the field of information technology, have simplified the use of video
data in various fields by the general public. This made it possible to store
large collections of video documents into computer systems. To enable efficient
use of these collections, it is necessary to develop tools to facilitate access
to these documents and handling them. In this paper we propose a method for
indexing and retrieval of video sequences in a video database of large
dimension, based on a weighting technique to calculate the degree of membership
of a concept in a video also a structuring of the data of the audio-visual
(context / concept / video) and a relevance feedback mechanism.
| arxiv topic:cs.MM cs.CV cs.IR |
arxiv_dataset-45351308.3325 | Lectures on Minimal Surface Theory
math.DG
An article based on a four-lecture introductory minicourse on minimal surface
theory given at the 2013 summer program of the Institute for Advanced Study and
the Park City Mathematics Institute.
| arxiv topic:math.DG |
arxiv_dataset-45361308.3425 | Experimental determination of conduction channels in atomic scale
conductors based on shot noise measurements
cond-mat.mes-hall
We present an experimental procedure for obtaining the conduction channels of
low-dimensional conductors based on shot noise measurements. The transmission
coefficient for each channel is determined numerically from the measured
conductance and Fano factor. The channel analysis is demonstrated for atomic
contacts of Ag, Au, Al and Pt, showing their channel evolution as a function of
conductance and mechanical elongation. This approach can be readily applied to
map the conduction channels in a wide range of nanoscale conductors under
different conditions.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-45371308.3525 | Direct test of the AdS/CFT correspondence by Monte Carlo studies of N=4
super Yang-Mills theory
hep-th hep-lat
We perform nonperturbative studies of N=4 super Yang-Mills theory by Monte
Carlo simulation. In particular, we calculate the correlation functions of
chiral primary operators to test the AdS/CFT correspondence. Our results agree
with the predictions obtained from the AdS side that the SUSY
non-renormalization property is obeyed by the three-point functions but
\emph{not} by the four-point functions investigated in this paper. Instead of
the lattice regularization, we use a novel regularization of the theory based
on an equivalence in the large-N limit between the N=4 SU(N) theory on RxS^3
and a one-dimensional SU(N) gauge theory known as the plane-wave (BMN) matrix
model. The equivalence extends the idea of large-N reduction to a curved space
and, at the same time, overcomes the obstacle related to the center symmetry
breaking. The adopted regularization preserves 16 SUSY, which is crucial in
testing the AdS/CFT correspondence with the available computer resources. The
only SUSY breaking effects, which come from the momentum cutoff $\Lambda$ in R
direction, are made negligible by using sufficiently large $\Lambda$.
| arxiv topic:hep-th hep-lat |
arxiv_dataset-45381308.3625 | Could $Z_{c}(4025)$ be a $J^{P}=1^{+}$ $D^{*}\bar{D^{*}}$ molecular
state?
hep-ph
We investigate whether the newly observed narrow resonance $Z_{c}(4025)$ can
be described as a $D^{*}\bar{D^{*}}$ molecular state with quantum numbers
$J^{P}=1^{+}$. Using QCD sum rules, we consider contributions up to dimension
six in the operator product expansion and work at leading order of
$\alpha_{s}$. The mass obtained for this state is $(4.05\pm 0.28) \mbox{GeV}$.
It is concluded that $D^{*}\bar{D^{*}}$ molecular state is a possible candidate
for $Z_{c}(4025)$.
| arxiv topic:hep-ph |
arxiv_dataset-45391308.3725 | Refined intersection homology on non-Witt spaces
math.GT math.DG
We develop a generalization to non-Witt spaces of the intersection homology
theory of Goresky-MacPherson. The second author has described the self-dual
sheaves compatible with intersection homology, and the other authors have
described a generalization of Cheeger's L2 de Rham cohomology. In this paper we
extend both of these cohomologies by describing all sheaf complexes in the
derived category of constructible sheaves that are compatible with middle
perversity intersection cohomology, though not necessarily self-dual. On
Thom-Mather stratified spaces this refined intersection cohomology theory
coincides with the analytic de Rham theory.
| arxiv topic:math.GT math.DG |
arxiv_dataset-45401308.3825 | Higher hairy graph homology
math.AT math.GT math.KT math.RT
We study the hairy graph homology of a cyclic operad; in particular we show
how to assemble corresponding hairy graph cohomology classes to form cocycles
for ordinary graph homology, as defined by Kontsevich. We identify the part of
hairy graph homology coming from graphs with cyclic fundamental group as the
dihedral homology of a related associative algebra with involution. For the
operads Comm, Assoc and Lie we compute this algebra explicitly, enabling us to
apply known results on dihedral homology to the computation of hairy graph
homology. In addition we determine the image in hairy graph homology of the
trace map defined in [CKV], as a symplectic representation.
For the operad Lie assembling hairy graph cohomology classes yields all known
non-trivial rational homology of Out(F_n). The hairy graph homology of Lie is
also useful for constructing elements of the cokernel of the Johnson
homomomorphism of a once-punctured surface.
| arxiv topic:math.AT math.GT math.KT math.RT |
arxiv_dataset-45411308.3925 | Distance Correlation Methods for Discovering Associations in Large
Astrophysical Databases
astro-ph.CO math.ST stat.AP stat.ML stat.TH
High-dimensional, large-sample astrophysical databases of galaxy clusters,
such as the Chandra Deep Field South COMBO-17 database, provide measurements on
many variables for thousands of galaxies and a range of redshifts. Current
understanding of galaxy formation and evolution rests sensitively on
relationships between different astrophysical variables; hence an ability to
detect and verify associations or correlations between variables is important
in astrophysical research. In this paper, we apply a recently defined
statistical measure called the distance correlation coefficient which can be
used to identify new associations and correlations between astrophysical
variables. The distance correlation coefficient applies to variables of any
dimension; it can be used to determine smaller sets of variables that provide
equivalent astrophysical information; it is zero only when variables are
independent; and it is capable of detecting nonlinear associations that are
undetectable by the classical Pearson correlation coefficient. Hence, the
distance correlation coefficient provides more information than the Pearson
coefficient. We analyze numerous pairs of variables in the COMBO-17 database
with the distance correlation method and with the maximal information
coefficient. We show that the Pearson coefficient can be estimated with higher
accuracy from the corresponding distance correlation coefficient than from the
maximal information coefficient. For given values of the Pearson coefficient,
the distance correlation method has a greater ability than the maximal
information coefficient to resolve astrophysical data into highly concentrated
V-shapes, which enhances classification and pattern identification. These
results are observed over a range of redshifts beyond the local universe and
for galaxies from elliptical to spiral.
| arxiv topic:astro-ph.CO math.ST stat.AP stat.ML stat.TH |
arxiv_dataset-45421308.4025 | Supersymmetric Custodial Triplets
hep-ph
We analyze the extension of the Minimal Supersymmetric Standard Model which
includes extra Y=(0,\pm 1) supersymmetric triplets with a global SU(2)_L
\otimes SU(2)_R symmetry spontaneousy broken to the custodial SU(2)_V by the
vacuum expectation value of the neutral scalar components of doublets and
triplets. The model is the supersymmetrization of the non-supersymmetric model
introduced long ago by Georgi and Machacek where the \rho-parameter is kept to
unity at the tree-level by the custodial symmetry. Accordingly the scalar
sector is classified into degenerate SU(2)_V multiplets: singlets, triplets
(including the one containing the Godstone bosons) and fiveplets. The singly
and doubly charged chiral superfields play a key role in the unitarization of
the theory. The couplings of the Standard Model-like Higgs to vector bosons
(including \gamma\gamma) and fermions, and the corresponding Higgs signal
strengths, are in agreement with LHC experimental data for a large region of
the parameter space. Breaking of custodial invariance by radiative corrections
suggests a low-scale mechanism of supersymmetry breaking.
| arxiv topic:hep-ph |
arxiv_dataset-45431308.4125 | Understanding Rulelog Computations in Silk
cs.SE cs.PL
Rulelog is a knowledge representation and reasoning language based on logic
programming under the well-founded semantics. It is an extension of the
language of Flora-2 and so supports inheritance and other object-oriented
features, as well as the higher-order syntax of Hilog. However, Rulelog rules
may also contain quantifiers and may be contra-positional. In addition, these
rules are evaluated in the presence of defeasibility mechanisms that include
rule cancellation, rule priorities, and other aspects. Rulelog programs are
sometimes developed by loosely coordinated teams of knowledge engineers (KEs)
who are not necessarily programmers. This requires not only declarative
debugging support, but also support for profiling to help KEs understand the
overall structure of a computation, including its termination properties. The
design of debugging and profiling tools is made more challenging because
Rulelog programs undergo a series of transformations into normal programs, so
that there is a cognitive distance between how rules are specified and how they
are executed.
In this paper, we describe the debugging and profiling environment for
Rulelog implemented in the integrated development environment of the Silk
system. Our approach includes an interface to justification graphs, which treat
why-not and defeasibility as well as provenance of the rules supporting
answers. It also includes tools for trace-based analysis of computations to
permit understanding of erroneous non-termination and of general performance
issues. For semantically correct cases of the non-terminating behavior, Silk
offers a different approach, which addresses the problem in a formally sound
manner by leveraging a form of bounded rationality called restraint.
| arxiv topic:cs.SE cs.PL |
arxiv_dataset-45441308.4225 | Macroscopic Quantum Phenomena from the Coupling Pattern and Entanglement
Structure Perspective
cond-mat.stat-mech quant-ph
We explore in this paper ways to qualify and quantify the quantum
entanglement $E(M)$ between two macroscopic objects by way of model studies.
Knowing that a macroscopic object is a composite, how does one determine $E(M)$
in terms of the entanglements between its micro-constituents $E(\mu)$? We
assert that the notion of `levels of structure', the coupling strength between
constituents in different levels, and the use of collective variables in each
level are all pertinent factors. We consider two types of coupling, each
constituent particle is coupled to only one other particle (1-to-1) versus it
coupled to all particles (1-to-all). In the 1-1 case with pairwise interactions
of equal strength, the entanglement is independent of the number of constituent
particles $N$ in the macroscopic object. In the 1-to-all case the relative
coordinates are decoupled and the center of mass (CoM) coupling scales with
$N$. We provide a proof of the conditions whereby the CoM variable decouples, a
cause for the special role the CoM variable plays in the entanglement between
the two such macroscopic objects. This qualitative behavior is largely not
affected by fluctuations in the interaction strength. We also analyzed the
entanglement pattern of 4 coupled oscillators in two pairs, representing the
two objects A and B (or two adjacent levels of structure), each with two
constituents. By assigning different coupling strengths we can investigate the
interplay of inter-level entanglement with intra- level interactions. From the
entanglement dynamics of the 4-oscillator system with varying coupling strength
we see the entanglement between constituents meeting sudden death while the CoM
variables may sustain over longer times. This offers another way to determine
under what conditions quantum entanglement between macroscopic objects can
persist.
| arxiv topic:cond-mat.stat-mech quant-ph |
arxiv_dataset-45451308.4325 | Foundation of Symbol Theory for Analytic Pseudodifferential Operators. I
math.AP
A new symbol theory for pseudodifferential operators in the complex analytic
category is given. This theory provides a cohomological foundation of symbolic
calculus.
| arxiv topic:math.AP |
arxiv_dataset-45461308.4425 | The Chern classes of the Verlinde bundles
math.AG
A formula for the first Chern class of the Verlinde bundle over the moduli
space of smooth genus g curves is given. A finite-dimensional argument is
presented in rank 2 using geometric symmetries obtained from strange duality,
relative Serre duality, and Wirtinger duality together with the projective
flatness of the Hitchin connection. A derivation using conformal-block methods
is presented in higher rank. An expression for the first Chern class over the
compact moduli space of curves is obtained.
| arxiv topic:math.AG |
arxiv_dataset-45471308.4525 | Reducing influence of antiferromagnetic interactions on ferromagnetic
properties of p-(Cd,Mn)Te quantum wells
cond-mat.mes-hall cond-mat.mtrl-sci
In order to explain the absence of hysteresis in ferromagnetic p-type
(Cd,Mn)Te quantum wells (QWs), spin dynamics was previously investigated by
Monte Carlo simulations combining the Metropolis algorithm with the
determination of hole eigenfunctions at each Monte Carlo sweep. Short-range
antiferromagnetic superexchange interactions between Mn spins - which compete
with the hole-mediated long-range ferromagnetic coupling - were found to
accelerate magnetization dynamics if the the layer containing Mn spins is wider
than the vertical range of the hole wave function. Employing this approach it
is shown here that appreciate magnitudes of remanence and coercivity can be
obtained if Mn ions are introduced to the quantum well in a delta-like fashion.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-45481308.4625 | Thermodynamic properties of microbian populations on biological
membranes
cond-mat.soft physics.bio-ph
In this work we to develop a general statistical mechanic formalism to study
systems restricted to surfaces of revolution, these are a very well model to
study the termodinamical properties of microbiological systems and
macromolecules lies on biological membranes such as cellular well.
| arxiv topic:cond-mat.soft physics.bio-ph |
arxiv_dataset-45491308.4725 | The environments of luminous radio galaxies and type-2 quasars
astro-ph.CO
We present the results of a comparison between the environments of 1) a
complete sample of 46 southern 2Jy radio galaxies at intermediate redshifts
(0.05 < z < 0.7), 2) a complete sample of 20 radio-quiet type-2 quasars (0.3 <
z < 0.41), and 3) a control sample of 107 quiescent early-type galaxies at 0.2
< z < 0.7 in the Extended Groth Strip (EGS). The environments have been
quantified using angular clustering amplitudes (Bgq) derived from deep optical
imaging data. Based on these comparisons, we discuss the role of the
environment in the triggering of powerful radio-loud and radio-quiet quasars.
When we compare the Bgq distributions of the type-2 quasars and quiescent
early-type galaxies, we find no significant difference between them. This is
consistent with the radio-quiet quasar phase being a short-lived but ubiquitous
stage in the formation of all massive early-type galaxies. On the other hand,
PRGs are in denser environments than the quiescent population, and this
difference between distributions of Bgq is significant at the 3 sigma level.
This result supports a physical origin of radio loudness, with high density gas
environments favouring the transformation of AGN power into radio luminosity,
or alternatively, affecting the properties of the supermassive black holes
themselves. Finally, focussing on the radio-loud sources only, we find that the
clustering of weak-line radio galaxies (WLRGs) is higher than the strong-line
radio galaxies (SLRGs), constituting a 3 sigma result. 82% of the 2Jy WLRGs are
in clusters, according to our definition (Bgq > 400) versus only 31% of the
SLRGs.
| arxiv topic:astro-ph.CO |
arxiv_dataset-45501308.4825 | A comprehensive near and far ultraviolet spectroscopic study of the hot
DA white dwarf G191-B2B
astro-ph.SR
We present a detailed spectroscopic analysis of the hot DA white dwarf
G191-B2B, using the best signal to noise, high resolution near and far UV
spectrum obtained to date. This is constructed from co-added \textit{HST} STIS
E140H, E230H, and \textit{FUSE} observations, covering the spectral ranges of
1150-3145\AA\, and 910-1185\AA\, respectively. With the aid of recently
published atomic data, we have been able to identify previously undetected
absorption features down to equivalent widths of only a few m\AA. In total, 976
absorption features have been detected to $3\sigma$ confidence or greater, with
947 of these lines now possessing an identification, the majority of which are
attributed to Fe and Ni transitions. In our survey, we have also potentially
identified an additional source of circumstellar material originating from Si
{\sc iii}. While we confirm the presence of Ge detected by \citet{vennes05a},
we do not detect any other species. Furthermore, we have calculated updated
abundances for C, N, O, Si, P, S, Fe, and Ni, while also calculating, for the
first time, an NLTE abundance for Al, deriving Al {\sc
iii}/H=$1.60_{-0.08}^{+0.07}\times{10}^{-7}$. Our analysis constitutes what is
the most complete spectroscopic survey of any white dwarf. All observed
absorption features in the \textit{FUSE} spectrum have now been identified, and
relatively few remain elusive in the STIS spectrum.
| arxiv topic:astro-ph.SR |
arxiv_dataset-45511308.4925 | Stability of BEC galactic dark matter halos
astro-ph.CO astro-ph.GA gr-qc hep-th
In this paper we show that spherically symmetric BEC dark matter halos, with
the $\sin r/r$ density profile, that accurately fit galactic rotation curves
and represent a potential solution to the cusp-core problem are unstable. We do
this by introducing back the density profiles into the fully time-dependent
Gross-Pitaevskii-Poisson system of equations. Using numerical methods to track
the evolution of the system, we found that these galactic halos lose mass at an
approximate rate of half of its mass in a time scale of dozens of Myr. We
consider this time scale is enough as to consider these halos are unstable and
unlikely to be formed. We provide some arguments to show that this behavior is
general and discuss some other drawbacks of the model that restrict its
viability.
| arxiv topic:astro-ph.CO astro-ph.GA gr-qc hep-th |
arxiv_dataset-45521308.5025 | Development of A Modified Quasi-periodic Undulator for HLS
physics.acc-ph physics.ins-det
A modified quasi periodic undulator (QPU) is developed and to be installed at
Hefei Light Source (HLS).Magnet dimensions optimization is applied. High
harmonics contamination is eliminated from the fundamental emission effectively
according to the field tests. The depression ratio of 3rd harmonic is increased
by an order of magnitude than the current device with other harmonics well
reduced simultaneously. The significance of the modification measure is
verified practically. The design, measurement and commissioning of the device
is described.
| arxiv topic:physics.acc-ph physics.ins-det |
arxiv_dataset-45531308.5125 | Discovering Latent Patterns from the Analysis of User-Curated Movie
Lists
cs.SI physics.soc-ph
User content curation is becoming an important source of preference data, as
well as providing information regarding the items being curated. One popular
approach involves the creation of lists. On Twitter, these lists might contain
accounts relevant to a particular topic, whereas on a community site such as
the Internet Movie Database (IMDb), this might take the form of lists of movies
sharing common characteristics. While list curation involves substantial
combined effort on the part of users, researchers have rarely looked at mining
the outputs of this kind of crowdsourcing activity. Here we study a large
collection of movie lists from IMDb. We apply network analysis methods to a
graph that reflects the degree to which pairs of movies are "co-listed", that
is, assigned to the same lists. This allows us to uncover a more nuanced
grouping of movies that goes beyond categorisation schemes based on attributes
such as genre or director.
| arxiv topic:cs.SI physics.soc-ph |
arxiv_dataset-45541308.5225 | Elastic and transition form factors of the \Delta(1232)
nucl-th hep-lat hep-ph nucl-ex
Predictions obtained with a confining, symmetry-preserving treatment of a
vector-vector contact interaction at leading-order in a widely used truncation
of QCD's Dyson-Schwinger equations are presented for \Delta and \Omega baryon
elastic form factors and the \gamma N -> \Delta transition form factors. This
simple framework produces results that are practically indistinguishable from
the best otherwise available, an outcome which highlights that the key to
describing many features of baryons and unifying them with the properties of
mesons is a veracious expression of dynamical chiral symmetry breaking in the
hadron bound-state problem. The following specific results are of particular
interest. The \Delta elastic form factors are very sensitive to m_\Delta.
Hence, given that the parameters which define extant simulations of
lattice-regularised QCD produce \Delta-resonance masses that are very large,
the form factors obtained therewith are a poor guide to properties of the
\Delta(1232). Considering the \Delta-baryon's quadrupole moment, whilst all
computations produce a negative value, the conflict between theoretical
predictions entails that it is currently impossible to reach a sound conclusion
on the nature of the \Delta-baryon's deformation in the infinite momentum
frame. Results for analogous properties of the \Omega baryon are less
contentious. In connection with the N->\Delta transition, the Ash-convention
magnetic transition form factor falls faster than the neutron's magnetic form
factor and nonzero values for the associated quadrupole ratios reveal the
impact of quark orbital angular momentum within the nucleon and \Delta; and,
furthermore, these quadrupole ratios do slowly approach their anticipated
asymptotic limits.
| arxiv topic:nucl-th hep-lat hep-ph nucl-ex |
arxiv_dataset-45551308.5325 | The Riemann-Roch theorem for graphs and the rank in complete graphs
math.CO
The paper by M. Baker and S. Norine in 2007 introduced a new parameter on
configurations of graphs and gave a new result in the theory of graphs which
has an algebraic geometry flavour. This result was called Riemann-Roch formula
for graphs since it defines a combinatorial version of divisors and their ranks
in terms of configuration on graphs. The so called chip firing game on graphs
and the sandpile model in physics play a central role in this theory.
In this paper we give a presentation of the theorem of Baker and Norine in
purely combinatorial terms, which is more accessible and shorter than the
original one. An algorithm for the determination of the rank of configurations
is also given for the complete graph $K_n$. This algorithm has linear
arithmetic complexity. The analysis of number of iterations in a less optimized
version of this algorithm leads to an apparently new parameter which we call
the prerank. This parameter and the classical area parameter provide an
alternative description to some well known $q,t$-Catalan numbers. Restricted to
a natural subset of configurations, the two natural statistics degree and rank
in Riemann-Roch formula lead to a distribution which is described by a
generating function which, up to a change of variables, is a symmetric fraction
involving two copies of Carlitz q-analogue of the Catalan numbers.
| arxiv topic:math.CO |
arxiv_dataset-45561308.5425 | Debye Sources, Beltrami Fields, and a Complex Structure on Maxwell
Fields
math.NA math-ph math.AP math.MP physics.plasm-ph
The Debye source representation for solutions to the time harmonic Maxwell
equations is extended to bounded domains with finitely many smooth boundary
components. A strong uniqueness result is proved for this representation.
Natural complex structures are identified on the vector spaces of time-harmonic
Maxwell fields. It is shown that in terms of Debye source data, these complex
structures are uniformized, that is, represented by a fixed linear map on a
fixed vector space, independent of the frequency. This complex structure
relates time-harmonic Maxwell fields to constant-k Beltrami fields, i.e.
solutions of the equation curl(E) = kE. A family of self-adjoint boundary
conditions are defined for the Beltrami operator. This leads to a proof of the
existence of zero-flux, constant-k, force-free Beltrami fields for any bounded
region in R^3, as well as a constructive method to find them. The family of
self-adjoint boundary value problems defines a new spectral invariant for
bounded domains in R^3.
| arxiv topic:math.NA math-ph math.AP math.MP physics.plasm-ph |
arxiv_dataset-45571308.5525 | Cosmological Perturbations from Hybrid Potentials
astro-ph.CO hep-th
Cosmological inflation is the dominating paradigm to account for observations
of the Cosmic Microwave Background (CMB). In this thesis, we study the
phenomenology of a class of particularly well motivated models of inflation,
known under the generic name of hybrid models. They are characterised by a
transition from a valley to a hilltop shaped potential. In particular, we study
three limiting regimes of the simplest realisation, hybrid inflation,
constraining its parameter space using observational bounds on the spectral
index and the non-gaussianity of the primordial perturbations. We find that the
model is highly constrained by observations, with large part of the parameter
space either ruled out by a blue spectral index ($n_s>1$) or by a large
non-gaussianity parameter $f_{rm NL}$, two quantities measured with precision
by PLANCK. However, there exists regions in parameter space leading to
interesting phenomenology compatibly with observational bounds. Also, a version
of hybrid inflation with a third light scalar field at horizon crossing is
derived from the supersymmetry framework. We find that the model can generate
observables within observational bounds.
| arxiv topic:astro-ph.CO hep-th |
arxiv_dataset-45581308.5625 | Shape identification and classification in echolocation
cs.NA
The paper aims at proposing the first shape identification and classification
algorithm in echolocation. The approach is based on first extracting geometric
features from the reflected waves and then matching them with precomputed ones
associated with a dictionary of targets. The construction of such
frequency-dependent shape descriptors is based on some important properties of
the scattering coefficients and new invariants. The stability and resolution of
the proposed identification algorithm with respect to measurement noise and the
limited-view aspect are analytically and numerically quantified.
| arxiv topic:cs.NA |
arxiv_dataset-45591308.5725 | Large deviations of empirical neighborhood distribution in sparse random
graphs
math.PR math.CO
Consider the Erd\H{o}s-Renyi random graph on n vertices where each edge is
present independently with probability c/n, with c>0 fixed. For large n, a
typical random graph locally behaves like a Galton-Watson tree with Poisson
offspring distribution with mean c. Here, we study large deviations from this
typical behavior within the framework of the local weak convergence of finite
graph sequences. The associated rate function is expressed in terms of an
entropy functional on unimodular measures and takes finite values only at
measures supported on trees. We also establish large deviations for other
commonly studied random graph ensembles such as the uniform random graph with
given number of edges growing linearly with the number of vertices, or the
uniform random graph with given degree sequence. To prove our results, we
introduce a new configuration model which allows one to sample uniform random
graphs with a given neighborhood distribution, provided the latter is supported
on trees. We also introduce a new class of unimodular random trees, which
generalizes the usual Galton Watson tree with given degree distribution to the
case of neighborhoods of arbitrary finite depth. These generalized Galton
Watson trees turn out to be useful in the analysis of unimodular random trees
and may be considered to be of interest in their own right.
| arxiv topic:math.PR math.CO |
arxiv_dataset-45601308.5825 | The puzzling radio source in the cool core cluster A 2626
astro-ph.CO
We report on new VLA radio observations performed at 1.4 GHz and 4.8 GHz with
unprecedented sensitivity and angular resolution (~1 arcsec) of the cool core
cluster A 2626, which is known to possess a radio mini-halo at its center. The
most unusual features of A 2626 are two elongated radio features detected in
previous observations to the north and south, having morphologies not common to
the typical jet-lobe structures in cool cores. In our new sensitive images the
two elongated features appears clearly as bright radio arcs, and we discover
the presence of a new arc to the west. These radio arcs are not detected at 4.8
GHz, implying a steep (alpha >1) spectrum, and their origin is puzzling. After
subtracting the flux density contributed by these discrete features from the
total flux measured at low resolution, we estimate a residual 18.0 +/- 1.8 mJy
flux density of diffuse radio emission at 1.4 GHz. We therefore confirm the
detection of diffuse radio emission, which appears distinct from the discrete
radio arcs embedded in it. Although its radio power is lower (1.4x10^23 W/Hz)
than previously known, the diffuse emission may still be classified as a radio
mini-halo.
| arxiv topic:astro-ph.CO |
arxiv_dataset-45611308.5925 | Quantum Peierls stress of straight and kinked dislocations and effect of
non-glide stresses
cond-mat.mtrl-sci
It was recently shown that to predict reliable Peierls stresses from
atomistic simulations, one has to correct the Peierls barrier by the zero-point
energy difference between the initial and activated states of the dislocation.
The corresponding quantum Peierls stresses are studied here in {\alpha}-Fe
modeled with two embedded atom method potentials. First, we show that the
quantum correction arises from modes localized near the dislocation core, such
that partial Hessian matrices built on small cylinders centered on the
dislocation core can be used to compute the zero-point energy difference.
Second, we compute quantum Peierls stresses for straight and kinked
dislocations and show that the former is smaller than the latter with both
{\alpha}-Fe models. Finally, we compare quantum Peierls stresses obtained in
simple shear and in traction along two orientations considered experimentally
by Kuramoto et al., evidencing a strong effect of non-glide stresses on the
quantum Peierls stress.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-45621308.6025 | Small-Support Approximate Correlated Equilibria
cs.GT
We prove the existence of approximate correlated equilibrium of support size
polylogarithmic in the number of players and the number of actions per player.
In particular, using the probabilistic method, we show that there exists a
multiset of polylogarithmic size such that the uniform distribution over this
multiset forms an approximate correlated equilibrium. Along similar lines, we
establish the existence of approximate coarse correlated equilibrium with
logarithmic support.
We complement these results by considering the computational complexity of
determining small-support approximate equilibria. We show that random sampling
can be used to efficiently determine an approximate coarse correlated
equilibrium with logarithmic support. But, such a tight result does not hold
for correlated equilibrium, i.e., sampling might generate an approximate
correlated equilibrium of support size \Omega(m) where m is the number of
actions per player. Finally, we show that finding an exact correlated
equilibrium with smallest possible support is NP-hard under Cook reductions,
even in the case of two-player zero-sum games.
| arxiv topic:cs.GT |
arxiv_dataset-45631308.6125 | Metropolis-Hastings thermal state sampling for numerical simulations of
Bose-Einstein condensates
cond-mat.quant-gas
We demonstrate the application of the Metropolis-Hastings algorithm to
sampling of classical thermal states of one-dimensional Bose-Einstein
quasicondensates in the classical fields approximation, both in untrapped and
harmonically trapped case. The presented algorithm can be easily generalized to
higher dimensions and arbitrary trap geometry. For truncated Wigner simulations
the quantum noise can be added with conventional methods (half a quantum of
energy in every mode). The advantage of the presented method over the usual
analytical and stochastic ones lies in its ability to sample not only from
canonical and grand canonical distributions, but also from the generalized
Gibbs ensemble, which can help to shed new light on thermodynamics of
integrable systems.
| arxiv topic:cond-mat.quant-gas |
arxiv_dataset-45641308.6225 | Voronoi's Conjecture for extensions of Voronoi parallelohedra
math.MG math.CO
Let $I$ be a segment in the $d$-dimensional Euclidean space $\mathbb E^d$.
Let $P$ and $P+I$ be parallelohedra in $\mathbb E^d$, where "+" denotes the
Minkowski sum. We prove that Voronoi's Conjecture holds for $P+I$, i.e. $P+I$
is a Voronoi parallelohedron for some Euclidean metric in $\mathbb E^d$, if
Voronoi's Conjecture holds for $P$.
| arxiv topic:math.MG math.CO |
arxiv_dataset-45651308.6325 | 26Al in the Early Solar System: Not so Unusual After All
astro-ph.EP
Recently acquired evidence shows that extrasolar asteroids exhibit over a
factor of 100 variation in the iron to aluminum abundance ratio. This large
range likely is a consequence of igneous differentiation that resulted from
heating produced by radioactive decay of 26Al with an abundance comparable to
that in the solar system's protoplanetary disk at birth. If so, the
conventional view that our solar system began with an unusually high amount of
26Al should be discarded.
| arxiv topic:astro-ph.EP |
arxiv_dataset-45661308.6425 | Causal dynamical triangulation for non-critical open-closed string field
theory
hep-th
We extend the 2 dimensional Causal Dynamical Triangulation (CDT) model from
the usual model of closed string to the one of open-closed string. The
matrix-vector model describing the loop gas model is modified so as to possess
the nature of the CDT, i.e. the time foliation structure. Stochastic
quantization method produces interactions of loop and line variables similar to
those in the non-critical open-closed string field theories. By taking an
appropriate scaling, we realize an extended model of the generalized CDT
(GCDT), which keeps the causality in a broad sense.
| arxiv topic:hep-th |
arxiv_dataset-45671308.6525 | A diffraction effect in X-ray area detectors
physics.ins-det cond-mat.other
When an X-ray area detector based on a single crystalline material, for
instance, a state of the art hybrid pixel detector, is illuminated from a point
source by monochromatic radiation, a pattern of lines appears which overlays
the detected image. These lines can be easily found by scattering experiments
with smooth patterns, such as small-angle X-ray scattering. The origin of this
effect is the Bragg reflection in the sensor layer of the detector.
Experimental images are presented over a photon energy range from 3.4 keV to 10
keV, together with a theoretical analysis. The intensity of this pattern is up
to 20%, which can disturb the evaluation of scattering and diffraction
experiments. The patterns can be exploited to check the alignment of the
detector surface with the direct beam, and the alignment of individual detector
modules with each other in the case of modular detectors, as well as for the
energy calibration of the radiation.
| arxiv topic:physics.ins-det cond-mat.other |
arxiv_dataset-45681308.6625 | Vector-like technineutron Dark Matter: is a QCD-type Technicolor ruled
out by XENON100?
hep-ph
We continue to explore a question about the existence of a new strongly
coupled dynamics above the electroweak scale. The latter has been recently
realized in the simplest consistent scenario, the vector-like (or
chiral-symmetric) Technicolor model based upon the gauged linear sigma-model.
One of the predictions of a new strong dynamics in this model, the existence of
stable vector-like technibaryon states at a TeV scale, such that the lightest
neutral one could serve as a Dark Matter candidate. Here, we consider the
QCD-type Technicolor with SU(3)_TC confined group and one SU(2)_W doublet of
vector-like techniquarks and test this model against existing Dark Matter
astrophysics data. We show that the spin-independent Dirac
technineutron-nucleon cross section is by far too large and ruled out by
XENON100 data. We conclude that vector-like techniquark sectors with an odd
group of confinement SU(2n+1)_TC, n=1,2,... and with ordinary vector-like weak
SU(2)_W interactions are excluded if the technibaryon number is conserved. We
discuss a possible generic TC scenario with a technibaryon sector interacting
via an extra vector SU(2)_V other than the standard weak SU(2)_W and consider
immediate implications for the cosmological evolution and freeze out of heavy
relic technineutrons.
| arxiv topic:hep-ph |
arxiv_dataset-45691308.6725 | Chirped Frequency Transfer with an accuracy of $10^{-18}$ and its
Application to the Remote Synchronisation of Timescales
physics.optics
We demonstrate combined high-fidelity long-haul transfer of a linearly
chirped, optical frequency and time transfer. In a proof-of-principle
experiment we transfer an optical frequency with a linear chirp of around 238
kHz/s via a phase-stabilized underground fiber link of 150 km. We find a
fractional frequency transfer instability (Allan deviation, 18000 s averaging
time) and simultaneity of the chirped frequency between both ends on a level of
around $2\times10^{-19}$, where the active phase stabilization suppresses
cumulative, symmetrical effects. In a second step, we demonstrate the remote
measurement of synchronisation taking advantage of chirped-frequency transfer.
The uncertainty of time transfer here is around 500 ps.
| arxiv topic:physics.optics |
arxiv_dataset-45701308.6825 | Enhancement of laser-driven electron acceleration in an ion channel
physics.plasm-ph
A long laser beam propagating through an underdense plasma produces a
positively charged ion channel by expelling plasma electrons in the transverse
direction. We consider the dynamics of a test electron in a resulting
two-dimensional channel under the action of the laser field and the transverse
electric field of the channel. A considerable enhancement of the axial momentum
can be achieved in this case via amplification of betatron oscillations. It is
shown that the oscillations can be parametrically amplified when the betatron
frequency, which increases with the wave amplitude, becomes comparable to the
frequency of its modulations. The modulations are caused by non-inertial
(accelerated/decelerated) relativistic axial motion induced by the wave
regardless of the angle between the laser electric field and the field of the
channel. We have performed a parameter scan for a wide range of wave amplitudes
and ion densities and we have found that, for a given density, there is a well
pronounced wave amplitude threshold above which the maximum electron energy is
considerably enhanced. We have also calculated a time-integrated electron
spectrum produced by an ensemble of electrons with a spread in the initial
transverse momentum. The numerical results show that the considerable energy
enhancement is accompanied by spectrum broadening. The presented mechanism of
energy enhancement is robust with respect to an axial increase of ion density,
because it relies on a threshold phenomenon rather than on a narrow linear
resonance.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-45711309.0092 | Harmonic morphisms and eigenfamilies on the exceptional Lie group G2
math.DG
We construct harmonic morphisms on the compact simple Lie group G2. The
construction uses eigenfamilies in a representation theoretic scheme.
| arxiv topic:math.DG |
arxiv_dataset-45721309.0192 | Reconstruction and uniqueness of moving obstacles
cs.DS cs.GR
We study the uniqueness and accuracy of the numerical solution of the problem
of reconstruction of the shape and trajectory of a reflecting obstacle moving
in an inhomogeneous medium from travel times, start and end points, and initial
angles of ultrasonic rays reflecting at the obstacle. The speed of sound in the
domain when there is no obstacle present is known and provided as an input
parameter which together with the other initial data enables the algorithm to
trace ray paths and find their reflection points. The reflection points
determine with high-resolution the shape and trajectory of the obstacle. The
method has predictable computational complexity and performance and is very
efficient when it is parallelized and optimized because only a small portion of
the domain is reconstructed.
| arxiv topic:cs.DS cs.GR |
arxiv_dataset-45731309.0292 | Minimal extension of General Relativity: alternative gravity model with
non-minimal coupling between matter and curvature
gr-qc
We examine an extension of General Relativity with an explicit non-minimal
coupling between matter and curvature. The purpose of this work is to present
an overview of the implications of the latter to various contexts, ranging from
astrophysical matter distributions to a cosmological setting. Various results
are discussed, including the impact of this non-minimal coupling on the choice
of Lagrangian density, on a mechanism to mimic galactic and cluster dark
matter, on the possibility of accounting for the accelerated expansion of the
Universe, energy density fluctuations and modifications to post-inflationary
reheating. The equivalence between a model exhibiting a non-minimal coupling
and multi-scalar-theories is also discussed.
| arxiv topic:gr-qc |
arxiv_dataset-45741309.0392 | Hierarchization for the Sparse Grid Combination Technique
cs.DC cs.NA
The sparse grid combination technique provides a framework to solve high
dimensional numerical problems with standard solvers. Hierarchization is
preprocessing step facilitating the communication needed for the combination
technique. The derived hierarchization algorithm outperforms the baseline by up
to 30x and achieves close to 5% of peak performance. It also shows stable
performance for the tested data sets of up to 1 GB.
| arxiv topic:cs.DC cs.NA |
arxiv_dataset-45751309.0492 | Commensurators of solvable S-arithmetic groups
math.GR
We show that the abstract commensurator of an S-arithmetic subgroup of a
solvable algebraic group over Q is isomorphic to the Q-points of an algebraic
group, and compare this with examples of nonlinear abstract commensurators of
S-arithmetic groups in positive characteristic. In particular, we include a
description of the abstract commensurator of the lamplighter group.
| arxiv topic:math.GR |
arxiv_dataset-45761309.0592 | On W_2 lifting of Frobenius of Algebraic Surfaces
math.AG
We completely decide which minimal algebraic surfaces in positive
characteristics allow a lifting of their Frobenius over the trucated witt rings
of lengh 2.
| arxiv topic:math.AG |
arxiv_dataset-45771309.0692 | Charge Quantization in the $\mathbb{CP}(1)$ Nonlinear Sigma-Model
hep-th hep-ph
We investigate the consistency conditions for matter fields coupled to the
four-dimensional (${\cal N} = 1$ supersymmetric) $\mathbb{CP}(1)$ nonlinear
sigma model (the coset space $SU(2)_G/U(1)_H$). We find that consistency
requires that the $U(1)_H$ charge of the matter be quantized, in units of half
of the $U(1)_H$ charge of the Nambu-Goldstone (NG) boson, if the matter has a
nonsingular kinetic term and the dynamics respect the full group $SU(2)_G$. We
can then take the linearly realized group $U(1)_H$ to comprise the weak
hypercharge group $U(1)_Y$ of the Standard Model. Thus we have charge
quantization without a Grand Unified Theory (GUT), completely avoiding problems
like proton decay, doublet-triplet splitting, and magnetic monopoles. We
briefly investigate the phenomenological implications of this model-building
framework. The NG boson is fractionally charged and completely stable. It can
be naturally light, avoiding constraints while being a component of dark matter
or having applications in nuclear physics. We also comment on the extension to
other NLSMs on coset spaces, which will be explored more fully in a followup
paper.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-45781309.0792 | Measurements according to Consistent Histories
quant-ph physics.hist-ph
We critically evaluate the treatment of the notion of measurement in the
Consistent Histories approach to quantum mechanics. We find such a treatment
unsatisfactory because it relies, often implicitly, on elements external to
those provided by the formalism. In particular, we note that, in order for the
formalism to be informative when dealing with measurement scenarios, one needs
to assume that the appropriate choice of framework is such that apparatuses are
always in states of well defined pointer positions after measurements. The
problem is that there is nothing in the formalism to justify this assumption.
We conclude that the Consistent Histories approach, contrary to what is claimed
by its proponents, fails to provide a truly satisfactory resolution for the
measurement problem in quantum theory.
| arxiv topic:quant-ph physics.hist-ph |
arxiv_dataset-45791309.0892 | A Coinductive Approach to Proof Search
cs.LO
We propose to study proof search from a coinductive point of view. In this
paper, we consider intuitionistic logic and a focused system based on
Herbelin's LJT for the implicational fragment. We introduce a variant of lambda
calculus with potentially infinitely deep terms and a means of expressing
alternatives for the description of the "solution spaces" (called B\"ohm
forests), which are a representation of all (not necessarily well-founded but
still locally well-formed) proofs of a given formula (more generally: of a
given sequent).
As main result we obtain, for each given formula, the reduction of a
coinductive definition of the solution space to a effective coinductive
description in a finitary term calculus with a formal greatest fixed-point
operator. This reduction works in a quite direct manner for the case of Horn
formulas. For the general case, the naive extension would not even be true. We
need to study "co-contraction" of contexts (contraction bottom-up) for dealing
with the varying contexts needed beyond the Horn fragment, and we point out the
appropriate finitary calculus, where fixed-point variables are typed with
sequents. Co-contraction enters the interpretation of the formal greatest fixed
points - curiously in the semantic interpretation of fixed-point variables and
not of the fixed-point operator.
| arxiv topic:cs.LO |
arxiv_dataset-45801309.0992 | Comment to the note "Counting of discrete Rossby/drift wave resonant
triads", arXiv:1309.0405
physics.flu-dyn
The main purpose of this note is clarify the following misunderstanding
apparent in the note arXiv:1309.0405 by M. Bustamante, U. Hayat, P. Lynch, B.
Quinn; [1]: the authors erroneously assume that in the manuscript
arXiv:1307.8272 by A. Kartashov and E. Kartashova, [2], resonant triads with
real amplitudes are counted whereas it can be seen explicitly from the form of
dynamical system that wave amplitudes are complex.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-45811309.1092 | The size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad
line region cloud X-ray eclipse
astro-ph.HE
We present results obtained from the time-resolved X-ray spectral analysis of
the Narrow-Line-Seyfert 1 galaxy SWIFT J2127.4+5654 during a ~130 ks XMM-Newton
observation. We reveal large spectral variations, especially during the first
~90 ks of the XMM-Newton exposure. The spectral variability can be attributed
to a partial eclipse of the X-ray source by an intervening low-ionization/cold
absorbing structure (cloud) with column density N_H = 2.0^{+0.2}_{-0.3}e22
cm^-2 which gradually covers and then uncovers the X-ray emitting region with
covering fraction ranging from zero to ~43 per cent. Our analysis enables us to
constrain the size, number density, and location of the absorbing cloud with
good accuracy. We infer a cloud size (diameter) of $D_c < 1.5e13 cm,
corresponding to a density of n_c > 1.5e9 cm^-3 at a distance of R_c > 4.3e16
cm from the central black hole. All of the inferred quantities concur to
identify the absorbing structure with one single cloud associated with the
broad line region of SWIFT J2127.4+5654. We are also able to constrain the
X-ray emitting region size (diameter) to be D_s < 2.3e13 cm which, assuming the
black hole mass estimated from single-epoch optical spectroscopy (1.5e7 M_sun),
translates into D_s < 10.5 gravitational radii (r_g) with larger sizes (in r_g)
being associated with smaller black hole masses, and viceversa. We also confirm
the presence of a relativistically distorted reflection component off the inner
accretion disc giving rise to a broad relativistic Fe K emission line and small
soft excess (small because of the high Galactic column density), supporting the
measurement of an intermediate black hole spin in SWIFT J2127.4+5654 that was
obtained from a previous Suzaku observation.
| arxiv topic:astro-ph.HE |
arxiv_dataset-45821309.1192 | Fourteen years of R/qtl: Just barely sustainable
stat.CO stat.AP
R/qtl is an R package for mapping quantitative trait loci (genetic loci that
contribute to variation in quantitative traits) in experimental crosses. Its
development began in 2000. There have been 38 software releases since 2001. The
latest release contains 35k lines of R code and 24k lines of C code, plus 15k
lines of code for the documentation. Challenges in the development and
maintenance of the software are discussed. A key to the success of R/qtl is
that it remains a central tool for the chief developer's own research work, and
so its maintenance is of selfish importance.
| arxiv topic:stat.CO stat.AP |
arxiv_dataset-45831309.1292 | $pp$ and $\bar pp$ total cross sections and elastic scattering
hep-ph hep-ex
It is shown that $p p$ and $p\bar p$ data, including those from the TOTEM
experiment, agree well with Regge theory.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-45841309.1392 | Bayesian Structural Inference for Hidden Processes
stat.ML cs.LG math.ST nlin.CD physics.data-an stat.TH
We introduce a Bayesian approach to discovering patterns in structurally
complex processes. The proposed method of Bayesian Structural Inference (BSI)
relies on a set of candidate unifilar HMM (uHMM) topologies for inference of
process structure from a data series. We employ a recently developed exact
enumeration of topological epsilon-machines. (A sequel then removes the
topological restriction.) This subset of the uHMM topologies has the added
benefit that inferred models are guaranteed to be epsilon-machines,
irrespective of estimated transition probabilities. Properties of
epsilon-machines and uHMMs allow for the derivation of analytic expressions for
estimating transition probabilities, inferring start states, and comparing the
posterior probability of candidate model topologies, despite process internal
structure being only indirectly present in data. We demonstrate BSI's
effectiveness in estimating a process's randomness, as reflected by the Shannon
entropy rate, and its structure, as quantified by the statistical complexity.
We also compare using the posterior distribution over candidate models and the
single, maximum a posteriori model for point estimation and show that the
former more accurately reflects uncertainty in estimated values. We apply BSI
to in-class examples of finite- and infinite-order Markov processes, as well to
an out-of-class, infinite-state hidden process.
| arxiv topic:stat.ML cs.LG math.ST nlin.CD physics.data-an stat.TH |
arxiv_dataset-45851309.1492 | Commodity futures and market efficiency
q-fin.ST
We analyze the market efficiency of 25 commodity futures across various
groups -- metals, energies, softs, grains and other agricultural commodities.
To do so, we utilize recently proposed Efficiency Index to find that the most
efficient of all the analyzed commodities is heating oil, closely followed by
WTI crude oil, cotton, wheat and coffee. On the other end of the ranking, we
detect live cattle and feeder cattle. The efficiency is also found to be
characteristic for specific groups of commodities -- energy commodities being
the most efficient and the other agricultural commodities (formed mainly of
livestock) the least efficient groups. We also discuss contributions of the
long-term memory, fractal dimension and approximate entropy to the total
inefficiency. Last but not least, we come across the nonstandard relationship
between the fractal dimension and Hurst exponent. For the analyzed dataset, the
relationship between these two is positive meaning that local persistence
(trending) is connected to global anti-persistence. We attribute this to
specifics of commodity futures which might be predictable in a short term and
locally but in a long term, they return to their fundamental price.
| arxiv topic:q-fin.ST |
arxiv_dataset-45861309.1592 | Symmetry energy, unstable nuclei, and neutron star crusts
nucl-th astro-ph.SR nucl-ex
Phenomenological approach to inhomogeneous nuclear matter is useful to
describe fundamental properties of atomic nuclei and neutron star crusts in
terms of the equation of state of uniform nuclear matter. We review a series of
researches that we have developed by following this approach. We start with
more than 200 equations of state that are consistent with empirical masses and
charge radii of stable nuclei and then apply them to describe matter radii and
masses of unstable nuclei, proton elastic scattering and total reaction cross
sections off unstable nuclei, and nuclei in neutron star crusts including
nuclear pasta. We finally discuss the possibility of constraining the density
dependence of the symmetry energy from experiments on unstable nuclei and even
observations of quasi-periodic oscillations in giant flares of soft gamma-ray
repeaters.
| arxiv topic:nucl-th astro-ph.SR nucl-ex |
arxiv_dataset-45871309.1692 | The Implementation of the Renormalized Complex MSSM in FeynArts and
FormCalc
hep-ph
We describe the implementation of the renormalized complex MSSM (cMSSM) in
the diagram generator FeynArts and the calculational tool FormCalc. This
extension allows to perform UV-finite one-loop calculations of cMSSM processes
almost fully automatically. The Feynman rules for the cMSSM with counterterms
are available as a new model file for FeynArts. Also included are default
definitions of the renormalization constants; this fixes the renormalization
scheme. Beyond that all model parameters are generic, e.g. we do not impose any
relations to restrict the number of input parameters. The model file has been
tested extensively for several non-trivial decays and scattering reactions. Our
renormalization scheme has been shown to give stable results over large parts
of the cMSSM parameter space.
| arxiv topic:hep-ph |
arxiv_dataset-45881309.1792 | Desktop and Mobile Web Page Comparison: Characteristics, Trends, and
Implications
cs.HC cs.CY
The broad proliferation of mobile devices in recent years has drastically
changed the means of accessing the World Wide Web. Describing a shift away from
the desktop computer era for content consumption, predictions indicate that the
main access of web-based content will come from mobile devices. Concurrently,
the manner of content presentation has changed as well; web artifacts are
allowing for richer media and higher levels of user interaction which is
enabled through increasing access networks speeds. This article provides an
overview of more than two years of high level web page characteristics by
comparing the desktop and mobile client versions. Our study is the first
long-term evaluation of differences as seen by desktop and mobile web browser
clients. We showcase the main differentiating factors with respect to the
number of web page object requests, their sizes, relationships, and web page
object caching. We additionally highlight long-term trends and discuss their
future implications.
| arxiv topic:cs.HC cs.CY |
arxiv_dataset-45891309.1892 | Dimension reduction of clustering results in bioinformatics
q-bio.QM q-bio.BM
OPTICS is a density-based clustering algorithm that performs well in a wide
variety of applications. For a set of input objects, the algorithm creates a
so-called reachability plot that can be either used to produce cluster
membership assignments, or interpreted itself as an expressive two-dimensional
representation of the density-based clustering structure of the input set, even
if the input set is embedded in higher dimensions. The main focus of this work
is a visualization method that can be used to assign colours to all entries of
the input database, based on hierarchically represented a-priori knowledge
available for each of these objects. Based on two different,
bioinformatics-related applications we illustrate how the proposed method can
be efficiently used to identify clusters with proven real-life relevance.
| arxiv topic:q-bio.QM q-bio.BM |
arxiv_dataset-45901309.1992 | Edge scattering of electrons in graphene
cond-mat.mes-hall
We discuss the contribution of edge scattering to the conductance of graphene
nanoribbons and nanoflakes. Using different possible types of the boundary
conditions for the electron wave function at the edge, we found dependences of
the momentum relaxation time and conductance on the geometric sizes and on the
carrier density. We also consider the case of ballistic nanoribbon and
nanodisc, for which the edge scaterring is the main mechanism of momentum
relaxation.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-45911309.2092 | Laser assisted Compton scattering of X-ray photons
physics.atom-ph hep-ph physics.optics
The Compton scattering of X-ray photons, assisted by a short intense optical
laser pulse, is discussed. The differential scattering cross section reveals
the interesting feature that the main Klein-Nishina line is accompanied by a
series of side-lines forming a broad plateau where up to ${\cal O} (10^3)$
laser photons participate simultaneously in a single scattering event. An
analytic formula for the width of the plateau is given. Due to the non-linear
mixing of X-ray and laser photons a frequency dependent rotation of the
polarization of the final state X-ray photons relative to the scattering plane
emerges. A consistent description of the scattering process with short laser
pulses requires to work with X-ray pulses. An experimental investigation can be
accomplished, e.g., at LCLS or the European XFEL in the near future.
| arxiv topic:physics.atom-ph hep-ph physics.optics |
arxiv_dataset-45921309.2192 | Quantum charge pumping in graphene-based devices: When lattice defects
do help
cond-mat.mes-hall cond-mat.mtrl-sci
Quantum charge pumping, the quantum coherent generation of a dc current at
zero bias through time dependent potentials, provides outstanding opportunities
for metrology and the development of new devices. The long electronic coherence
times and high quality of the crystal structure of graphene may provide
suitable building blocks for such quantum pumps. Here, we focus in adiabatic
quantum pumping through graphene nanoribbons in the Fabry-P\'{e}rot regime
highlighting the crucial role of defects by using atomistic simulations. We
show that even a single defect added to the pristine structure may produce a
two orders of magnitude increase in the pumped charge.
| arxiv topic:cond-mat.mes-hall cond-mat.mtrl-sci |
arxiv_dataset-45931309.2292 | Infrared absorption by graphene-hBN heterostructures
cond-mat.mes-hall
We propose a theory of optical absorption in monolayer graphene-hexagonal
boron nitride (hBN) heterostructures. In highly oriented heterostructures, the
hBN underlay produces a long-range moir\'e superlattice potential for the
graphene electrons which modifies the selection rules for absorption of
incoming photons in the infrared to visible frequency range. The details of the
absorption spectrum modification depend on the relative strength of the various
symmetry-allowed couplings between the graphene electrons and the hBN, and the
resulting nature of the reconstructed band structure.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-45941309.2392 | On the Coordinate System of Space-Weather HMI Active Region Patches
(SHARPs): A Technical Note
astro-ph.SR astro-ph.IM
We describe the coordinate systems of two streams of HMI active region vector
data. A distinction is made between (a) the 2D grid on which the field vector
is measured (or sampled), and (b) the 3D coordinate established at each grid
point, in which the field vector is presented. The HMI data reduction can
involve coordinate changes on both, with those performed on the former termed
"remapping", the latter "vector transformation". Relevant pipeline procedures
are described. Useful examples are given for data analysis.
| arxiv topic:astro-ph.SR astro-ph.IM |
arxiv_dataset-45951309.2492 | The influence of spin-phonon coupling on antiferromagnetic spin
fluctuations in FeSe under pressure: the First-principles calculations with
van der Waals corrections
cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el
The electronic structures, lattice dynamics, and magnetic properties of
crystal {\beta}-FeSe under hydrostatic pressure have been studied by using the
first-principles electronic structure calculations with van der Waals (vdW)
corrections. With applied pressures, the energy bands around the Fermi energy
level consisting mainly of Fe-3d orbitals show obvious energy shifts and
occupation variations, and meanwhile the frequencies of all optical phonon
modes increase. Among these phonon modes, the A1g mode, which relates to the Se
height from the Fe-Fe plane, shows a clear frequency jump in the range between
5 and 6 GPa. This is also the pressure range within which the highest
superconducting transition temperature Tc of FeSe is reached in experiments. In
comparison with the other phonon modes, the zero-point vibration of the A1g
mode induces the strongest fluctuation of local magnetic moment on Fe under a
pressure from 0 to 9 GPa, and the induced fluctuation reaches the maximum
around 5 GPa. These results suggest that the effect of phonon via spin-phonon
coupling need to be considered when exploring the superconducting mechanism in
iron-based superconductors.
| arxiv topic:cond-mat.supr-con cond-mat.mtrl-sci cond-mat.str-el |
arxiv_dataset-45961309.2592 | Da investiga\c{c}\~ao sobre a natureza da luz \`a relatividade especial:
notas de aula
physics.hist-ph
It is shown as experiments and theories about the nature of light led to the
special theory of relativity. The most important facts for the emergence of the
theory proposed by Einstein in 1905 are presented.
| arxiv topic:physics.hist-ph |
arxiv_dataset-45971309.2692 | Equivariant, string and leading order characteristic classes associated
to fibrations
math-ph math.DG math.MP
We construct equivariant, string and leading order characteristic classes and
Chern-Simons classes for certain infinite rank bundles associated to fibrations
occurring in loop spaces, Gromov-Witten theory and gauge theory. Results
include a restatement of the S^1 index theorem using equivariant classes on the
tangent bundle to loop space; the expression of some GW invariants in terms of
string and leading order classes for infinite rank bundles over moduli spaces
of pseudoholomorphic curves for semipositive symplectic manifolds; the
identification of the real cohomology of a loop group with certain string and
leading order classes; the identification of Donaldson's nu-class for
4-manifolds with a leading order class for the fibration of irreducible
connections A over the quotient A/G by the gauge group.
| arxiv topic:math-ph math.DG math.MP |
arxiv_dataset-45981309.2792 | Fano resonances of microwave structures with embedded magneto-dipolar
quantum dots
physics.optics cond-mat.mtrl-sci
Long range dipole-dipole correlation in a ferromagnetic sample can be treated
in terms of collective excitations of the system as a whole. Ferrite samples
with linear dimensions smaller than the dephasing length, but still much larger
than the exchange-interaction scales are mesoscopic structures. Recently, it
was shown that mesoscopic quasi-2D ferrite disks, distinguishing by
multiresonance magneto-dipolar-mode (MDM) spectra, demonstrate unique
properties of artificial atomic structures: energy eigenstates, eigen
power-flow vortices and eigen helicity parameters. Because of these properties,
MDMs in a ferrite disk enable the confinement of microwave radiation to
subwavelength scales. In microwave structures with embedded MDM ferrite
samples, one can observe quantized fields with topologically distinctive
characteristics. The use of a quasi-2D ferrite-disk scatterer with internal MDM
resonance spectra along the channel propagation direction could change the
transmission dramatically. In this paper, we show that interaction of the MDM
ferrite particle with its environment has a deep analogy with the
Fano-resonance interference observed in natural and artificial atomic
structures. We characterize the observed effect as Fano-resonance interference
in MDM quantum dots.
| arxiv topic:physics.optics cond-mat.mtrl-sci |
arxiv_dataset-45991309.2892 | Nonlinear pressure dependence of T_N in almost multiferroic EuTiO_3
cond-mat.mtrl-sci
The antiferromagnetic (AFM) phase transition temperature T_N of EuTiO_3 has
been studied as a function of pressure p. The data reveal a nonlinear
dependence of T_N on p with T_N increasing with increasing pressure. The
exchange interactions exhibit an analogous dependence on p as T_N (if the
absolute value of the nearest neighbor interaction is considered) and there is
evidence that the AFM transition is robust with increasing pressure. The
corresponding Weiss temperature {\Theta}_W remains anomalous since it always
exhibits positive values. The data are analyzed within the Bloch power law
model and provide excellent agreement with experiment.
| arxiv topic:cond-mat.mtrl-sci |
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