title: Atkin and Swinnerton-Dyer congruences and noncongruence modular forms

abstract:
  Atkin and Swinnerton-Dyer congruences are special congruence recursions
satisfied by coefficients of noncongruence modular forms. These are in some
sense $p$-adic analogues of Hecke recursion satisfied by classic Hecke
eigenforms. They actually appeared in different context and sometimes can be
obtained using the theory of formal groups. In this survey paper, we introduce
the Atkin and Swinnerton-Dyer congruences, and discuss some recent progress on
this topic.


title: $f(T)$ theories from holographic dark energy models

abstract:
  We reconstruct $f(T)$ theories from three different holographic dark energy
models in different time durations. For the HDE model, the dark energy
dominated era with new setting up is chosen for reconstruction, and the
radiation dominated era is chosen when the involved model changes into NADE.
For the RDE model, radiation, matter and dark energy dominated time durations
are all investigated. We also investigate the limitation which prevents an
arbitrary choice of the time duration for reconstruction in HDE and NADE, and
find that an improved boundary condition is needed for a more precise
reconstruction of $f(T)$ theory.


title:
Calibrating High-Precision Faraday Rotation Measurements for LOFAR and
  the Next Generation of Low-Frequency Radio Telescopes

abstract:
  Faraday rotation measurements using the current and next generation of
low-frequency radio telescopes will provide a powerful probe of astronomical
magnetic fields. However, achieving the full potential of these measurements
requires accurate removal of the time-variable ionospheric Faraday rotation
contribution. We present ionFR, a code that calculates the amount of
ionospheric Faraday rotation for a specific epoch, geographic location, and
line-of-sight. ionFR uses a number of publicly available, GPS-derived total
electron content maps and the most recent release of the International
Geomagnetic Reference Field. We describe applications of this code for the
calibration of radio polarimetric observations, and demonstrate the high
accuracy of its modeled ionospheric Faraday rotations using LOFAR pulsar
observations. These show that we can accurately determine some of the
highest-precision pulsar rotation measures ever achieved. Precision rotation
measures can be used to monitor rotation measure variations - either intrinsic
or due to the changing line-of-sight through the interstellar medium. This
calibration is particularly important for nearby sources, where the ionosphere
can contribute a significant fraction of the observed rotation measure. We also
discuss planned improvements to ionFR, as well as the importance of ionospheric
Faraday rotation calibration for the emerging generation of low-frequency radio
telescopes, such as the SKA and its pathfinders.


title:
From mechanical folding trajectories to intrinsic energy landscapes of
  biopolymers

abstract:
  In single molecule laser optical tweezer (LOT) pulling experiments a protein
or RNA is juxtaposed between DNA handles that are attached to beads in optical
traps. The LOT generates folding trajectories under force in terms of
time-dependent changes in the distance between the beads. How to construct the
full intrinsic folding landscape (without the handles and the beads) from the
measured time series is a major unsolved problem. By using rigorous theoretical
methods---which account for fluctuations of the DNA handles, rotation of the
optical beads, variations in applied tension due to finite trap stiffness, as
well as environmental noise and the limited bandwidth of the apparatus---we
provide a tractable method to derive intrinsic free energy profiles. We
validate the method by showing that the exactly calculable intrinsic free
energy profile for a Generalized Rouse Model, which mimics the two-state
behavior in nucleic acid hairpins, can be accurately extracted from simulated
time series in a LOT setup regardless of the stiffness of the handles. We next
apply the approach to trajectories from coarse grained LOT molecular
simulations of a coiled-coil protein based on the GCN4 leucine zipper, and
obtain a free energy landscape that is in quantitative agreement with
simulations performed without the beads and handles. Finally, we extract the
intrinsic free energy landscape from experimental LOT measurements for the
leucine zipper, which is independent of the trap parameters.

categories: q-bio.BM cond-mat.soft cond-mat.stat-mech physics.bio-ph


title: Multiple Criteria Problems over Minkowski Balls

abstract:
  Under study are some vector optimization problems over the space of Minkowski
balls, i.e., symmetric convex compact subsets in Euclidean space. A typical
problem requires to achieve the best result in the presence of conflicting
goals; e.g., given the surface area of a symmetric convex body $\mathfrak x$,
we try to maximize the volume of $\mathfrak x$ and minimize the width of
$\mathfrak x$ simultaneously.


title:
Unconventional and Exotic Magnetism in Carbon-Based Structures and
  Related Materials

abstract:
  The detailed analysis of the problem of possible magnetic behavior of the
carbon-based structures was fulfilled to elucidate and resolve (at least
partially) some unclear issues. It was the purpose of the present paper to look
somewhat more critically into some conjectures which have been made and to the
peculiar and contradictory experimental results in this rather indistinct and
disputable field. Firstly the basic physics of magnetism was briefly addressed.
Then a few basic questions were thoroughly analyzed and critically reconsidered
to elucidate the possible relevant mechanism (if any) which may be responsible
for observed peculiarities of the "magnetic" behavior in these systems. The
arguments supporting the existence of the intrinsic magnetism in carbon-based
materials, including pure graphene were analyzed critically. It was concluded
that recently published works have shown clearly that the results of the
previous studies, where the "ferromagnetism" was detected in pure graphene,
were incorrect. Rather, graphene is strongly diamagnetic, similar to graphite.
Thus the possible traces of a quasi-magnetic behavior which some authors
observed in their samples may be attributed rather to induced magnetism due to
the impurities, defects, etc. On the basis of the present analysis the
conclusion was made that the thorough and detailed experimental studies of
these problems only may shed light on the very complicated problem of the
magnetism of carbon-based materials. Lastly the peculiarities of the magnetic
behavior of some related materials and the trends for future developments were
mentioned.


title:
Sensitivity analysis for HJB equations with an application to coupled
  backward-forward systems

abstract:
  In this paper, we analyse Lipschitz continuous dependence of the solution to
Hamilton-Jacobi-Bellman equations on a functional parameter. This sensitivity
analysis not only has the interest on its own, but also is important for the
mean field games methodology, namely for solving a coupled system of
backward-forward equations. We show that the unique solution to a
Hamilton-Jacobi-Bellman equation and its spacial gradient are Lipschitz
continuous uniformly with respect to the functional parameter. In particular,
we provide verifiable criteria for the so-called feedback regularity condition.
Finally as an application, we show how the sensitive results are used to solved
the coupled system of backward-forward equations.


title: PDE approximation of large systems of differential equations

abstract:
  A large system of ordinary differential equations is approximated by a
parabolic partial differential equation with dynamic boundary condition and a
different one with Robin boundary condition. Using the theory of differential
operators with Wentzell boundary conditions and similar theories, we give
estimates on the order of approximation. The theory is demonstrated on a voter
model where the Fourier method applied to the PDE is of great advantage.


title:
Stochastic filtering via L2 projection on mixture manifolds with
  computer algorithms and numerical examples

abstract:
  We examine some differential geometric approaches to finding approximate
solutions to the continuous time nonlinear filtering problem. Our primary focus
is a new projection method for the optimal filter infinite dimensional
Stochastic Partial Differential Equation (SPDE), based on the direct L2 metric
and on a family of normal mixtures. We compare this method to earlier
projection methods based on the Hellinger distance/Fisher metric and
exponential families, and we compare the L2 mixture projection filter with a
particle method with the same number of parameters, using the Levy metric. We
prove that for a simple choice of the mixture manifold the L2 mixture
projection filter coincides with a Galerkin method, whereas for more general
mixture manifolds the equivalence does not hold and the L2 mixture filter is
more general. We study particular systems that may illustrate the advantages of
this new filter over other algorithms when comparing outputs with the optimal
filter. We finally consider a specific software design that is suited for a
numerically efficient implementation of this filter and provide numerical
examples.


title:
Convergence to the Tracy-Widom distribution for longest paths in a
  directed random graph

abstract:
  We consider a directed graph on the 2-dimensional integer lattice, placing a
directed edge from vertex $(i_1,i_2)$ to $(j_1,j_2)$, whenever $i_1 \le j_1$,
$i_2 \le j_2$, with probability $p$, independently for each such pair of
vertices. Let $L_{n,m}$ denote the maximum length of all paths contained in an
$n \times m$ rectangle. We show that there is a positive exponent $a$, such
that, if $m/n^a \to 1$, as $n \to \infty$, then a properly centered/rescaled
version of $L_{n,m}$ converges weakly to the Tracy-Widom distribution. A
generalization to graphs with non-constant probabilities is also discussed.


title:
Exploring covalently bonded diamondoid particles with valence
  photoelectron spectroscopy

abstract:
  We investigated the valence electronic structure of diamondoid particles in
the gas phase, utilizing valence photoelectron spectroscopy. The samples were
singly or doubly covalently bonded dimers or trimers of the lower diamondoids.
Both the bond type and the combination of bonding partners are shown to affect
the overall electronic structure. For singly bonded particles, we observe a
small impact of the bond on the electronic structure, whereas for doubly bonded
particles, the connecting bond determines the electronic structure of the
highest occupied orbitals. In the singly bonded particles a superposition of
the bonding partner orbitals determines the overall electronic structure. The
experimental findings are supported by density functional theory computations
at the M06-2X/cc-pVDZ level of theory.


title:
Morphogenesis of defects and tactoids during isotropic-nematic phase
  transition in self-assembled lyotropic chromonic liquid crystals

abstract:
  We explore the structure of nuclei and topological defects in the first-order
phase transition between the nematic (N) and isotropic (I) phases in lyotropic
chromonic liquid crystals (LCLCs). The LCLCs are formed by self-assembled
molecular aggregates of various lengths and show a broad biphasic region. The
defects emerge as a result of two mechanisms. 1) Surface anisotropy mechanism
that endows each N nucleus (tactoid) with topological defects thanks to
preferential (tangential) orientation of the director at the closed I-N
interface, and 2) Kibble mechanism with defects forming when differently
oriented N tactoids merge with each other. Different scenarios of phase
transition involve positive (N-in-I) and negative (I-in-N) tactoids with
non-trivial topology of the director field and also multiply connected
tactoids-in-tactoids configurations. The closed I-N interface limiting a
tactoid shows a certain number of cusps; the lips of the interface on the
opposite sides of the cusp make an angle different from pi. The N side of each
cusp contains a point defect-boojum. The number of cusps shows how many times
the director becomes perpendicular to the I-N interface when one
circumnavigates the closed boundary of the tactoid. We derive conservation laws
that connect the number of cusps c to the topological strength m of defects in
the N part of the simply-connected and multiply-connected tactoids. We
demonstrate how the elastic anisotropy of the N phase results in non-circular
shape of the disclination cores. A generalized Wulff construction is used to
derive the shape of I and N tactoids as the function of I-N interfacial tension
anisotropy in the frozen director field of various topological charges m. The
complex shapes and structures of tactoids and topological defects demonstrate
an important role of surface anisotropy in morphogenesis of phase transitions
in liquid crystals.


title: A Link Splitting Spectral Sequence in Khovanov Homology

abstract:
  We construct a new spectral sequence beginning at the Khovanov homology of a
link and converging to the Khovanov homology of the disjoint union of its
components. The page at which the sequence collapses gives a lower bound on the
splitting number of the link, the minimum number of times its components must
be passed through one another in order to completely separate them. In
addition, we build on work of Kronheimer-Mrowka and Hedden-Ni to show that
Khovanov homology detects the unlink.


title:
Structure of complex networks: Quantifying edge-to-edge relations by
  failure-induced flow redistribution

abstract:
  The analysis of complex networks has so far revolved mainly around the role
of nodes and communities of nodes. However, the dynamics of interconnected
systems is commonly focalised on edge processes, and a dual edge-centric
perspective can often prove more natural. Here we present graph-theoretical
measures to quantify edge-to-edge relations inspired by the notion of flow
redistribution induced by edge failures. Our measures, which are related to the
pseudo-inverse of the Laplacian of the network, are global and reveal the
dynamical interplay between the edges of a network, including potentially
non-local interactions. Our framework also allows us to define the embeddedness
of an edge, a measure of how strongly an edge features in the weighted cuts of
the network. We showcase the general applicability of our edge-centric
framework through analyses of the Iberian Power grid, traffic flow in road
networks, and the C. elegans neuronal network.


title:
EAST: Energy Efficient Adaptive Scheme for Transmission in Wireless
  Sensor Networks

abstract:
  In this paper, we propose Energy-efficient Adaptive Scheme for Transmission
(EAST) in WSNs. EAST is IEEE 802.15.4 standard compliant. In this approach,
open-loop is used for temperature-aware link quality estimation and
compensation. Whereas, closed-loop feedback helps to divide network into three
logical regions to minimize overhead of control packets on basis of Threshold
transmitter power loss (RSSIloss) for each region and current number of
neighbor nodes that help to adapt transmit power according to link quality
changes due to temperature variation. Simulation results show that propose
scheme; EAST effectively adapts transmission power to changing link quality
with less control packets overhead and energy consumption compared to classical
approach with single region in which maximum transmitter power assigned to
compensate temperature variation.


title:
Quantum Monte Carlo Calculations with Chiral Effective Field Theory
  Interactions

abstract:
  We present the first quantum Monte Carlo (QMC) calculations with chiral
effective field theory (EFT) interactions. To achieve this, we remove all
sources of nonlocality, which hamper the inclusion in QMC calculations, in
nuclear forces to next-to-next-to-leading order. We perform auxiliary-field
diffusion Monte Carlo (AFDMC) calculations for the neutron matter energy up to
saturation density based on local leading-order, next-to-leading order, and
next-to-next-to-leading order nucleon-nucleon interactions. Our results exhibit
a systematic order-by-order convergence in chiral EFT and provide
nonperturbative benchmarks with theoretical uncertainties. For the softer
interactions, perturbative calculations are in excellent agreement with the
AFDMC results. This work paves the way for QMC calculations with systematic
chiral EFT interactions for nuclei and nuclear matter, for testing the
perturbativeness of different orders, and allows for matching to lattice QCD
results by varying the pion mass.

categories: nucl-th cond-mat.quant-gas hep-ph nucl-ex


title: Confronting brane inflation with Planck and pre-Planck data

abstract:
  In this paper, we compare brane inflation models with the Planck data and the
pre-Planck data (which combines WMAP, ACT, SPT, BAO and H0 data). The Planck
data prefer a spectral index less than unity at more than 5\sigma confidence
level, and a running of the spectral index at around 2\sigma confidence level.
We find that the KKLMMT model can survive at the level of 2\sigma only if the
parameter $\beta$ (the conformal coupling between the Hubble parameter and the
inflaton) is less than $\mathcal{O}(10^{-3})$, which indicates a certain level
of fine-tuning. The IR DBI model can provide a slightly larger negative running
of spectral index and red tilt, but in order to be consistent with the
non-Gaussianity constraints from Planck, its parameter also needs fine-tuning
at some level.


title: Contact and Momentum Distribution of the Unitary Fermi Gas

abstract:
  A key quantity in strongly-interacting resonant Fermi gases is the contact
$\mathcal{C}$, which characterizes numerous properties such as the momentum
distribution at large momenta or the pair correlation function at short
distances. The temperature dependence of $\mathcal{C}$ was measured at
unitarity, where existing theoretical predictions differ substantially even at
the qualitative level. We report accurate data for the contact and the momentum
distribution of the unitary gas in the normal phase, obtained by Bold
Diagrammatic Monte Carlo and Borel resummation. Our results agree with
experimental data within error bars and provide crucial benchmarks for the
development of advanced theoretical treatments and precision measurements.

categories: cond-mat.quant-gas cond-mat.str-el nucl-th physics.comp-ph


title:
On cohomological obstructions to the existence of log symplectic
  structures

abstract:
  We prove that a compact log symplectic manifold has a class in the second
cohomology group whose powers, except maybe for the top, are nontrivial. This
result gives cohomological obstructions for the existence of b-log symplectic
structures similar to those in symplectic geometry.


title: Ordinary Muon Capture in Hydrogen Reexamined

abstract:
  The rate of muon capture in a muonic hydrogen atom is calculated in
heavy-nucleon chiral perturbation theory up to next-to-next-to leading order.
To this order, we present the systematic evaluation of all the corrections due
to the QED and electroweak radiative corrections and the proton-size effect.
Since the low-energy constants involved can be determined from other
independent sources of information, the theory has predictive power. For the
hyperfine-singlet $\mu p$ capture rate $\Gamma_0$, our calculation gives
$\Gamma_0=710 \,\pm 5\,s^{-1}$, which is in excellent agreement with the
experimental value obtained in a recent high-precision measurement by the MuCap
Collaboration.


title: On supercycle lengths of active SU UMa stars

abstract:
  We performed a detailed analysis of extensive photometric observations of a
sample of most active dwarf novae, that is SU UMa stars which are characterised
by supercycle lengths shorter than 120 days. We found the observational
evidence that supercycle lengths for these objects have been constantly
increasing over the past decades, which indicates that their mean mass transfer
rates have been decreasing during that time. This seems to be a common feature
for this type of stars. We present numerical results in each case and estimate
time scales of future development of these systems. This study is important in
the context of evolution of dwarf novae stars and perhaps other cataclysmic
variables.


title:
A Derivation of the Source-Channel Error Exponent using Non-identical
  Product Distributions

abstract:
  This paper studies the random-coding exponent of joint source-channel coding
for a scheme where source messages are assigned to disjoint subsets (referred
to as classes), and codewords are independently generated according to a
distribution that depends on the class index of the source message. For
discrete memoryless systems, two optimally chosen classes and product
distributions are found to be sufficient to attain the sphere-packing exponent
in those cases where it is tight.


title:
Equatorial circular orbits of neutral test particles in the Kerr--Newman
  spacetime

abstract:
  We present a detailed analysis of the orbital circular motion of electrically
neutral test particles on the equatorial plane of the Kerr-Newman spacetime.
Many details of the motion in the cases of black hole and naked singularity
sources are pointed out. We identify four different types of orbital regions,
which depend on the properties of the orbital angular momentum, and define four
different kinds of naked singularities, according to the values of the
charge-to-mass ratio of the source. It is shown that the presence of a
particular type of counter-rotating test particles is sufficient to uniquely
identify naked singularities. It is pointed out that the structure of the
stability regions can be used to differentiate between black holes and naked
singularities.


title: Multi-marginal optimal transport on Riemannian manifolds

abstract:
  We study a multi-marginal optimal transportation problem on a Riemannian
manifold, with cost function given by the average distance squared from
multiple points to their barycenter. Under a standard regularity condition on
the first marginal, we prove that the optimal measure is unique and
concentrated on the graph of a function over the first variable, thus inducing
a Monge solution. This result generalizes McCann's polar factorization theorem
on manifolds from 2 to several marginals, in the same sense that a well known
result of Gangbo and Swiech generalizes Brenier's polar factorization theorem
on $\mathbb{R}^n$.


title:
Kinetics of excitations on the Fermi arcs in underdoped cuprates at low
  temperature

abstract:
  The Fermi-liquid-like (FL) resistivity recently observed in clean HgBa2CuO4
below the pseudogap temperature was related to carriers at the nodal points on
the Fermi surface [4]. We show that this necessitates important implications
for the electronic spectrum of underdoped (UD) cuprates in whole. Photoemission
experiments picture the spectrum as of metallic arcs separated from each other
by regions with large energy gaps. We solved the kinetic equation in such model
rigorously. The Fermi arcs carriers contribute to FL resistivity, if scattering
between the opposite nodal points admits the Umklapp processes. The Hall
coefficient defines the effective number of carriers on arcs and has the
positive sign. For clean materials the expression is applicable only at weak
magnetic fields. We discuss the Fermi arcs concept further in light of recent
experimental findings and argue that the idea of reconstructed FS in UD
cuprates is not consistent with the FL-like resistivity.


title: Wess-Zumino Inflation in Light of Planck

abstract:
  We discuss cosmological inflation in the minimal Wess-Zumino model with a
single massive chiral supermultiplet. With suitable parameters and assuming a
plausible initial condition at the start of the inflationary epoch, the model
can yield scalar perturbations in the Cosmic Microwave Background (CMB) of the
correct strength with a spectral index n_s ~ 0.96 and a tensor-to-scalar
perturbation ratio r < 0.1, consistent with the Planck CMB data. We also
discuss the possibility of topological inflation within the Wess-Zumino model,
and the possibility of combining it with a seesaw model for neutrino masses.
This would violate R-parity, but at such a low rate that the lightest
supersymmetric particle would have a lifetime long enough to constitute the
astrophysical cold dark matter.


title:
The total top quark pair production cross-section at hadron colliders
  through O(alpha_S^4)

abstract:
  We compute the next-to-next-to-leading order (NNLO) QCD correction to the
total cross-section for the reaction gg \to t\bar t + X. Together with the
partonic channels we computed previously, the result derived in this letter
completes the set of NNLO QCD corrections to the total top pair production
cross-section at hadron colliders. Supplementing the fixed order results with
soft-gluon resummation with next-to-next-to-leading logarithmic accuracy we
estimate that the theoretical uncertainty of this observable due to unknown
higher order corrections is about 3% at the LHC and 2.2% at the Tevatron. We
observe a good agreement between the Standard Model predictions and the
available experimental measurements. The very high theoretical precision of
this observable allows a new level of scrutiny in parton distribution functions
and new physics searches.


title: Spectator field models in light of spectral index after Planck

abstract:
  We revisit spectator field models including curvaton and modulated reheating
scenarios, specifically focusing on their viability in the new Planck era,
based on the derived expression for the spectral index in general spectator
field models. Importantly, the recent Planck observations give strong
preference to a red-tilted power spectrum, while the spectator field models
tend to predict a scale-invariant one. This implies that, during inflation,
either (i) the Hubble parameter varies significantly as in chaotic inflation,
or (ii) a scalar potential for the spectator field has a relatively large
negative curvature. Combined with the tight constraint on the non-Gaussianity,
the Planck data provides us with rich implications for various spectator field
models.


title:
Some results in the theory of genuine representations of the metaplectic
  double cover of GSp2n(F) over p-adic fields

abstract:
  Let F be a p-adic field and let G(n) and G`(n) be the metaplectic double
covers of the general symplectic group and symplectic group attached to a 2n
dimensional symplectic space over F. We show here that if n is odd then all the
genuine irreducible representations of G(n) are induced from a normal subgroup
of finite index closely related to G`(n). Thus, we reduce, in this case, the
theory of genuine admissible representations of G(n) to the better understood
corresponding theory of G`(n). For odd n we also prove the uniqueness of
certain Whittaker functionals along with Rodier type of Heredity. Our results
apply also to all parabolic subgroups of G(n) if n is odd and to some of the
parabolic subgroups of G(n) if n is even. We prove some irreducibility criteria
for parabolic induction on G(n) for both even and odd n. As a corollary we
show, among other results, that while for odd n, all genuine principal series
representations of G(n) induced from unitary representations are irreducible,
there exist reducibility points on the unitary axis if n is even. We also list
all the reducible genuine principal series representations of G(2) provided
that the F is not 2-adic.


title: Sampling exactly from the normal distribution

abstract:
  An algorithm for sampling exactly from the normal distribution is given. The
algorithm reads some number of uniformly distributed random digits in a given
base and generates an initial portion of the representation of a normal deviate
in the same base. Thereafter, uniform random digits are copied directly into
the representation of the normal deviate. Thus, in contrast to existing
methods, it is possible to generate normal deviates exactly rounded to any
precision with a mean cost that scales linearly in the precision. The method
performs no extended precision arithmetic, calls no transcendental functions,
and, indeed, uses no floating point arithmetic whatsoever; it uses only simple
integer operations. It can easily be adapted to sample exactly from the
discrete normal distribution whose parameters are rational numbers.


title:
Field-angle-resolved anisotropy in superconducting CeCoIn5 using
  realistic Fermi surfaces

abstract:
  We compute the field-angle-resolved specific heat and thermal conductivity
using realistic model band structure for the heavy-fermion superconductor
CeCoIn5 to identify the gap structure and location of nodes. We use a two-band
tight-binding parametrization of the band dispersion as input for the
self-consistent calculations in the quasiclassical formulation of the
superconductivity. Systematic analysis shows that modest in-plane anisotropy in
the density of states and Fermi velocity in tetragonal crystals significantly
affects the fourfold oscillations in thermal quantities, when the magnetic
field is rotated in the basal plane. The Fermi surface anisotropy substantially
shifts the location of the lines in the H-T plane, where the oscillations
change sign compared to quasicylindrical model calculations. In particular, at
high fields, the anisotropy and sign reversal are found even for isotropic
gaps. Our findings imply that a simultaneous analysis of the specific heat and
thermal conductivity, with an emphasis on the low energy sector, is needed to
restrict potential pairing scenarios in multiband superconductors. We discuss
the impact of our results on recent measurements of the Ce-115 family, namely
CeTIn5 with T=Co,Rh,Ir.


title:
Symmetric genuine Spherical Whittaker functions on the metaplectic
  double cover of GSp(2n,F)

abstract:
  Let F be a p-adic field of odd residual characteristic. Let G(n) and G`(n) be
the metaplectic double covers of the general symplectic group and the
symplectic group attached to the 2n dimensional symplectic space over F. Let T
be a genuine, possibly reducible, unramified principal series representation of
G(n). In these notes we give an explicit formulas for a spanning set for the
space of Spherical Whittaker functions attached to T. For odd n, and
generically for even n, this spanning set is a basis. The signicant property of
this set is that each of its elements is unchanged under the action of the Weyl
group of G`(n). If n is odd then each element in the set has an equivariant
property that generalizes the uniqueness result of Gelbart, Howe and
Piatetski-Shapiro proven for G(1). Using this symmetric set, we construct a
family of reducible genuine unramified principal series representations which
have more then one generic constituent. This family contains all the reducible
genuine unramified principal series representations induced from a unitary data
and exists only for n even.


title:
E-HORM: An Energy-efficient Hole Removing Mechanism in Wireless Senor
  Networks

abstract:
  Cluster based routing protocols forWireless Sensor Networks (WSNs) have been
widely used for better performance in terms of energy efficiency. Efficient use
of energy is challenging task of designing these protocols. Energy holes are
created due to quickly drain the energy of a few nodes due to nonuniform node
distribution in the network. Normally, energy holes make the data routing
failure when nodes transmit data back to the sink. We propose
Energy-efficientHOle Removing Mechanism (E-HORM) technique to remove energy
holes. In this technique, we use sleep and awake mechanism for sensor nodes to
save energy. This approach finds the maximum distance nodes to calculate the
maximum energy for data transmission. We consider it as a threshold energy Eth.
Every node first checks its energy level for data transmission. If the energy
level of node is less than Eth, it cannot transmit data.


title:
Heralded Mapping of Photonic Entanglement into Single Atoms in Free
  Space: Proposal for a Loophole-Free Bell Test

abstract:
  An obvious way to entangle two atoms located at remote locations is to
produce a pair of entangled photons half-way between the two atoms, to sent one
photon to each location and to subsequently map the photonic entanglement into
the atoms. The efficiency of this process is, however, fundamentally limited
due to overall transmission losses. We propose a method to herald the success
of the mapping operation in free space without destroying nor revealing the
stored quantum state. Interestingly for a Bell test, the heralding signal does
not open the detection loophole provided the measurement choice is performed
once the heralding is obtained only. We show through a detailed feasibility
study that this approach could provide an attractive alternative to Bell tests
where the atom--atom entanglement is created from atom--photon entanglement
using an entanglement swapping operation.


title:
On summability, integrability and impulsive differential equations in
  Banach spaces

abstract:
  We shall first study summability of families in normed spaces indexed with
well ordered sets of real numbers extended by infinity. Obtained results and a
generalized iteration method are applied to derive necessary and sufficient
conditions for HK, HL, Bochner and Riemann integrability of step mappings and
for right regulated mappings from an interval of reals extended by infinity to
a Banach space. Finally, solvability of impulsive differential equations are
studied.


title:
Chern connection of a pseudo-Finsler metric as a family of affine
  connections

abstract:
  We consider the Chern connection of a (conic) pseudo-Finsler manifold $(M,L)$
as a linear connection $\nabla^V$ on any open subset $\Omega\subset M$
associated to any vector field $V$ on $\Omega$ which is non-zero everywhere.
This connection is torsion-free and almost metric compatible with respect to
the fundamental tensor $g$. Then we show some properties of the curvature
tensor $R^V$ associated to $\nabla^V$ and in particular we prove that the
Jacobi operator of $R^V$ along a geodesic coincides with the one given by the
Chern curvature.


title: Giant magneto-drag in graphene at charge neutrality

abstract:
  We report experimental data and theoretical analysis of Coulomb drag between
two closely positioned graphene monolayers in weak magnetic field. Close enough
to the neutrality point, coexistence of electrons and holes in each layer leads
to a dramatic increase of the drag resistivity. Away from charge neutrality, we
observe non-zero Hall drag. The observed phenomena are explained by decoupling
of electric and quasiparticle currents which are orthogonal at charge
neutrality. The sign of magneto-drag depends on the energy relaxation rate and
geometry of the sample.


title:
MESA and NuGrid simulations of classical novae: CO and ONe nova
  nucleosynthesis

abstract:
  Classical novae are the result of thermonuclear flashes of hydrogen accreted
by CO or ONe white dwarfs, leading eventually to the dynamic ejection of the
surface layers. These are observationally known to be enriched in heavy
elements, such as C, O and Ne that must originate in layers below the H-flash
convection zone. Building on our previous work, we now present stellar
evolution simulations of ONe novae and provide a comprehensive comparison of
our models with published ones. Some of our models include exponential
convective boundary mixing to account for the observed enrichment of the nova
ejecta even when accreted material has a solar abundance distribution. Our
models produce maximum temperature evolution profiles and nucleosynthesis
yields in good agreement with models that generate enriched ejecta by assuming
that the accreted material was pre-mixed. We confirm for ONe novae the result
we reported previously, i.e.\ we found that $^3$He could be produced {\it in
situ} in solar-composition envelopes accreted with slow rates ($\dot{M} <
10^{-10}\,M_\odot/\mbox{yr}$) by cold ($T_{\rm WD} < 10^7$ K) CO WDs, and that
convection was triggered by $^3$He burning before the nova outburst in that
case. In addition, we now find that the interplay between the $^3$He production
and destruction in the solar-composition envelope accreted with an intermediate
rate, e.g.\ $\dot{M} = 10^{-10}\,M_\odot/\mbox{yr}$, by the $1.15\,M_\odot$ ONe
WD with a relatively high initial central temperature, e.g.\ $T_{\rm WD} =
15\times 10^6$ K, leads to the formation of a thick radiative buffer zone that
separates the bottom of the convective envelope from the WD surface. (Abridged)


title: Numerical evidence of the axial magnetic effect

abstract:
  The axial magnetic field, which couples to left- and right-handed fermions
with opposite signs, may generate an equilibrium dissipationless energy flow of
fermions in the direction of the field even in the presence of interactions. We
report on numerical observation of this Axial Magnetic Effect in quenched SU(2)
lattice gauge theory. We find that in the deconfinement (plasma) phase the
energy flow grows linearly with the increase of the strength of the axial
magnetic field. In the confinement (hadron) phase the Axial Magnetic Effect is
absent. Our study indirectly confirms the existence of the Chiral Vortical
Effect since both these effects have the same physical origin related to the
presence of the gravitational anomaly.


title:
Dark Radiation or Warm Dark Matter from long lived particle decays in
  the light of Planck

abstract:
  Although Planck data supports the standard \Lambda CDM model, it still allows
for the presence of Dark Radiation corresponding up to about half an extra
standard neutrino species. We propose a scenario for obtaining a fractional
"effective neutrino species" from a thermally produced particle which decays
into a much lighter stable relic plus standard fermions. At lifetimes much
longer than 1 sec, both the relic particles and the non-thermal neutrino
component contribute to Dark Radiation. By increasing the stable-to-unstable
particle mass ratio, the relic particle no longer acts as Dark Radiation but
instead becomes a candidate for Warm Dark Matter with mass O(1keV - 100GeV). In
both cases it is possible to address the lithium problem.


title: Representing Kirchberg algebras as inverse semigroup crossed products

abstract:
  In this note we show that a combinatorial model of Kirchberg algebras in the
UCT, namely the Katsura algebras O_{AB}, can be expressed both as groupoid
C*-algebras and as inverse semigroup crossed products. We use this picture to
obtain results about simplicity, pure infiniteness and nuclearity of O_{AB}
using different methods than those used by Katsura.


title:
SASI Activity in Three-Dimensional Neutrino-Hydrodynamics Simulations of
  Supernova Cores

abstract:
  The relevance of the standing accretion shock instability (SASI) compared to
neutrino-driven convection in three-dimensional (3D) supernova-core
environments is still highly controversial. Studying a 27 Msun progenitor, we
demonstrate, for the first time, that violent SASI activity can develop in 3D
simulations with detailed neutrino transport despite the presence of
convection. This result was obtained with the Prometheus-Vertex code with the
same sophisticated neutrino treatment so far used only in 1D and 2D models.
While buoyant plumes initially determine the nonradial mass motions in the
postshock layer, bipolar shock sloshing with growing amplitude sets in during a
phase of shock retraction and turns into a violent spiral mode whose growth is
only quenched when the infall of the Si/SiO interface leads to strong shock
expansion in response to a dramatic decrease of the mass accretion rate. In the
phase of large-amplitude SASI sloshing and spiral motions, the postshock layer
exhibits nonradial deformation dominated by the lowest-order spherical
harmonics (l=1, m=0,-1,+1) in distinct contrast to the higher multipole
structures associated with neutrino-driven convection. We find that the SASI
amplitudes, shock asymmetry, and nonradial kinetic energy in 3D can exceed
those of the corresponding 2D case during extended periods of the evolution. We
also perform parametrized 3D simulations of a 25 Msun progenitor, using a
simplified, gray neutrino transport scheme, an axis-free Yin-Yang grid, and
different amplitudes of random seed perturbations. They confirm the importance
of the SASI for another progenitor, its independence of the choice of spherical
grid, and its preferred growth for fast accretion flows connected to small
shock radii and compact proto-neutron stars as previously found in 2D setups.


title: A Lower Bound on the Mass of Cold Thermal Dark Matter from Planck

abstract:
  We show that the new measurement of the effective number of neutrinos Neff by
the Planck satellite can be used to set a robust lower bound on the mass of
cold thermal dark matter of O(MeV). Our limit applies if the dark matter
remains in thermal equilibrium by coupling to electrons and photons or through
interactions with neutrinos, and applies regardless of whether the dark matter
annihilation cross-section is s-wave or p-wave. To illustrate our bounds we
apply them to a model of a supersymmetric neutralino annihilating to neutrinos,
via a light mixed left-right handed sneutrino mediator. While this scenario was
not constrained by previous data, the Planck limits on Neff allow us to set a
lower bound on the neutralino dark matter mass of 3.5 MeV.


title: Preferential Attachment in Online Networks: Measurement and Explanations

abstract:
  We perform an empirical study of the preferential attachment phenomenon in
temporal networks and show that on the Web, networks follow a nonlinear
preferential attachment model in which the exponent depends on the type of
network considered. The classical preferential attachment model for networks by
Barab\'asi and Albert (1999) assumes a linear relationship between the number
of neighbors of a node in a network and the probability of attachment. Although
this assumption is widely made in Web Science and related fields, the
underlying linearity is rarely measured. To fill this gap, this paper performs
an empirical longitudinal (time-based) study on forty-seven diverse Web network
datasets from seven network categories and including directed, undirected and
bipartite networks. We show that contrary to the usual assumption, preferential
attachment is nonlinear in the networks under consideration. Furthermore, we
observe that the deviation from linearity is dependent on the type of network,
giving sublinear attachment in certain types of networks, and superlinear
attachment in others. Thus, we introduce the preferential attachment exponent
$\beta$ as a novel numerical network measure that can be used to discriminate
different types of networks. We propose explanations for the behavior of that
network measure, based on the mechanisms that underly the growth of the network
in question.


title:
A Comment on the calculation of the Lie algebra cocycle in the book Loop
  Groups

abstract:
  An expression for the Lie algebra cocycle corresponding to the central
extension of the group GLres(H) is derived in the book Loop Groups [1]. It will
be shown in this paper that some of the terms in this expression are ambiguous
and in order to be evaluated correctly the trace operation must be properly
defined.


title:
Quantum Mechanics in Noninertial Reference Frames: Violations of the
  Nonrelativistic Equivalence Principle

abstract:
  In previous work we have developed a formulation of quantum mechanics in
non-inertial reference frames. This formulation is grounded in a class of
unitary cocycle representations of what we have called the Galilean line group,
the generalization of the Galilei group that includes transformations amongst
non-inertial reference frames. These representations show that in quantum
mechanics, just as is the case in classical mechanics, the transformations to
accelerating reference frames give rise to fictitious forces. A special feature
of these previously constructed representations is that they all respect the
non-relativistic equivalence principle, wherein the fictitious forces
associated with linear acceleration can equivalently be described by
gravitational forces. In this paper we exhibit a large class of cocycle
representations of the Galilean line group that violate the equivalence
principle. Nevertheless the classical mechanics analogue of these cocycle
representations all respect the equivalence principle.


title:
Quantum Mechanics in non-inertial reference frames: time-dependent
  rotations and loop prolongations

abstract:
  This is the fourth in a series of papers on developing a formulation of
quantum mechanics in non-inertial reference frames. This formulation is
grounded in a class of unitary cocycle representations of what we have called
the Galilean line group, the generalization of the Galilei group to include
transformations amongst non-inertial reference frames. These representations
show that in quantum mechanics, just as the case in classical mechanics, the
transformations to accelerating reference frames give rise to fictitious
forces. In previous work, we have shown that there exist representations of the
Galilean line group that uphold the non-relativistic equivalence principle as
well as representations that violate the equivalence principle. In these
previous studies, the focus was on linear accelerations. In this paper, we
undertake an extension of the formulation to include rotational accelarations.
We show that the incorporation of rotational accelerations requires a class of
\emph{loop prolongations} of the Galilean line group and their unitary cocycle
representations. We recover the centrifugal and Coriolis force effects from
these loop representations. Loops are more general than groups in that their
multiplication law need not be associative. Hence, our broad theoretical claim
is that a Galilean quantum theory that holds in arbitrary non-inertial
reference frames requires going beyond groups and group representations, the
well-stablished framework for implementing symmetry transformations in quantum
mechanics.


title:
Asymptotic Solutions of the Kinetic Boltzmann Equation, Multicomponent
  Non-equilibrium Gas Dynamics and Turbulence

abstract:
  In the article correct method for the kinetic Boltzmann equation asymptotic
solution is formulated, the Hilbert's and Enskog's methods are discussed. The
equations system of multicomponent non-equilibrium gas dynamics is derived,
that corresponds to the first order in the approximate (asymptotic) method for
solution of the system of kinetic Boltzmann equations. It is shown, that the
velocity distribution functions of particles, obtained by the proposed method
and by Enskog's method, within Enskog's approach, are equivalent up to the
infinitesimal first order terms of the asymptotic expansion, but, generally
speaking, differ in the next order. Interpretation of turbulent gas flow is
proposed, as stratified on components gas flow, which is described by the
derived equations system of multicomponent non-equilibrium gas dynamics.


title:
Two-Fluid Dark Energy Models in Bianchi Type-III Universe with Variable
  Deceleration Parameter

abstract:
  Some new exact solutions of Einstein's field equations have come forth within
the scope of a spatially homogeneous and anisotropic Bianchi type-III
space-time filled with barotropic fluid and dark energy by considering a
variable deceleration parameter. We consider the case when the dark energy is
minimally coupled to the perfect fluid as well as direct interaction with it.
Under the suitable condition, the anisotropic models approach to isotropic
scenario. We also find that during the evolution of the universe, the equation
of state (EoS) for dark energy $\omega^{(de)}$, in both cases, tends to -1
(cosmological constant, $\omega^{(de)} = -1$), by displaying various patterns
as time increases, which is consistent with recent observations. The cosmic
jerk parameter in our derived models are in good agreement with the recent data
of astrophysical observations under appropriate condition. It is observed that
the universe starts from an asymptotic Einstein static era and reaches to the
$\Lambda$CDM model. So from recently developed Statefinder parameters, the
behavior of different stages of the universe has been studied. The physical and
geometric properties of cosmological models are also discussed.


title: Laplace transform in spaces of ultradistributions

abstract:
  The Laplace transform in Komatsu ultradistributions is considered. Also,
conditions are given under which an analytic function is a Laplace
transformation of an ultradistribution.


title:
A new approach to microscopic modeling of a hole transfer in
  heteropolymer DNA

abstract:
  Thermal oscillations of base pairs in the Peyrard-Bishop-Holstein model are
simulated by stochastic fluctuations of base overlap integrals. Numerical
investigation of the model is carried out for a hole transfer in $G_1A_2G_3G_4$
sequence which was previously studied experimentally by F. Lewis et al. A hole
migration between $G_1$ and $G_3G_4$ is determined by the matrix elements of
the charge transition, but presence and amplitude of their stochastic
fluctuations proved to play a key role in reproduction of the experimental
kinetics. Good agreement with the experimental data was obtained for a wide
range of the model parameters' combinations.


title:
Recurring flares from supermassive black hole binaries: implications for
  tidal disruption candidates and OJ 287

abstract:
  I discuss the possibility that accreting supermassive black hole (SMBH)
binaries with sub-parsec separations produce periodically recurring luminous
outbursts that interrupt periods of relative quiescence. This hypothesis is
motivated by two characteristics found generically in simulations of binaries
embedded in prograde accretion discs: (i) the formation of a central,
low-density cavity around the binary, and (ii) the leakage of gas into this
cavity, occurring once per orbit via discrete streams on nearly radial
trajectories. The first feature would reduce the emergent optical/UV flux of
the system relative to active galactic nuclei powered by single SMBHs, while
the second can trigger quasiperiodic fluctuations in luminosity. I argue that
the quasiperiodic accretion signature may be much more dramatic than previously
thought, because the infalling gas streams can strongly shock-heat via
self-collision and tidal compression, thereby enhancing viscous accretion. Any
optically thick gas that is circularized about either SMBH can accrete before
the next pair of streams is deposited, fueling transient, luminous flares that
recur every orbit. Due to the diminished flux in between accretion episodes,
such cavity-accretion flares could plausibly be mistaken for the tidal
disruptions of stars in quiescent nuclei. The flares could be distinguished
from tidal disruption events if their quasiperiodic recurrence is observed, or
if they are produced by very massive SMBHs that cannot disrupt solar-type
stars. They may be discovered serendipitously in surveys such as LSST or
eROSITA. I present a heuristic toy model as a proof of concept for the
production of cavity-accretion flares, and generate mock light curves and
specta. I also apply the model to the active galaxy OJ 287, whose production of
quasiperiodic pairs of optical flares has long fueled speculation that it hosts
a SMBH binary.


title: Imprints of feedback in young gasless clusters?

abstract:
  We present the results of N-body simulations in which we take the masses,
positions and velocities of sink particles from five pairs of hydrodynamical
simulations of star formation by Dale et al. (2012, 2013) and evolve them for a
further 10Myr. We compare the dynamical evolution of star clusters that formed
under the influence of mass-loss driven by photoionization feedback, to the
evolution of clusters that formed without feedback. We remove any remaining gas
and follow the evolution of structure in the clusters (measured by the
Q-parameter), half-mass radius, central density, surface density and the
fraction of bound stars. There is little discernible difference in the
evolution of clusters that formed with feedback compared to those that formed
without. The only clear trend is that all clusters which form without feedback
in the hydrodynamical simulations lose any initial structure over 10Myr,
whereas some of the clusters which form with feedback retain structure for the
duration of the subsequent N-body simulation. This is due to lower initial
densities (and hence longer relaxation times) in the clusters from Dale et al.
(2012, 2013) which formed with feedback, which prevents dynamical mixing from
erasing substructure. However, several other conditions (such as supervirial
initial velocities) also preserve substructure, so at a given epoch one would
require knowledge of the initial density and virial state of the cluster in
order to determine whether star formation in a cluster has been strongly
influenced by feedback.


title: Absorption signatures of warm-hot gas at low redshift: NeVIII

abstract:
  At z<1 a large fraction of the baryons is thought to reside in diffuse gas
that has been shock-heated to high temperatures (log T=5-6). Absorption by the
770.41, 780.32 {\AA} doublet of NeVIII in quasar spectra represents a unique
tool to study this elusive warm-hot phase. We have developed an analytic model
for the properties of NeVIII absorbers that allows for an inhomogeneous metal
distribution. Our model agrees with the predictions of a simulation from the
OWLS project indicating that the average line-of-sight metal-filling fraction
within the absorbing gas is low (c_L~0.1). Most of the NeVIII in our model is
produced in low-density, collisionally ionized gas (log n=-6 to -4 cm^-3, log
T=5-6). Strong NeVIII absorbers (log N(NeVIII)>14), like those recently
detected by HST/COS, are found to arise in higher density gas (log n>-4, log
T=5.75). NeVIII cloudlets harbour only 1 per cent of the cosmic baryon budget.
The baryon content of the surrounding gas (which has similar densities and
temperatures as the NeVIII cloudlets) is a factor 1/c_L higher. We conclude
that NeVIII absorbers are robust probes of shock-heated diffuse gas, but that
spectra with signal-to-noise ratios S/N>100 would be required to detect the
bulk of the baryons in warm-hot gas.


title:
Sensitive Search For Radio Variables And Transients In The Extended
  Chandra Deep-Field South

abstract:
  We report on an analysis of the Extended Chandra Deep Field South (E-CDFS)
region using archival data from the Very Large Array, with the goal of studying
radio variability and transients at the sub-mJy level. The 49 epochs of E-CDFS
observations at 1.4 GHz sample timescales from one day to 3 months. We find
that only a fraction (1%) of unresolved radio sources above 40 uJy are variable
at the 4-sigma level. There is no evidence that the fractional variability
changes along with the known transition of radio source populations below one
milliJansky. Optical identifications of the sources show that the variable
radio emission is associated with the central regions of an active galactic
nucleus or a star-forming galaxy. After a detailed comparison of the efficacy
of various source-finding algorithms, we use the best to carry out a transient
search. No transients were found. This implies that the areal density of
transients with peak flux density greater than 0.21 mJy is less than 0.37
deg^-2 (at a confidence level of 95%). This result is approximately an order of
magnitude below the transient rate measured at 5 GHz by Bower et al. (2007) but
it is consistent with more recent upper limits from Frail et al. (2012). Our
findings suggest that the radio sky at 1.4 GHz is relatively quiet. For
multi-wavelength transient searches, such as the electromagnetic counterparts
to gravitational waves, this frequency may be optimal for reducing the high
background of false positives.


title: Galactic accretion and the outer structure of galaxies in the CDM model

abstract:
  We have combined the semi-analytic galaxy formation model of Guo et al.
(2011) with the particle-tagging technique of Cooper et al. (2010) to predict
galaxy surface brightness profiles in a representative sample of ~1900 massive
dark matter haloes (10^12--10^14 M_sol) from the Millennium II Lambda-CDM
N-body simulation. Here we present our method and basic results focusing on the
outer regions of galaxies, consisting of stars accreted in mergers. These
simulations cover scales from the stellar haloes of Milky Way-like galaxies to
the 'cD envelopes' of groups and clusters, and resolve low surface brightness
substructure such as tidal streams. We find that the surface density of
accreted stellar mass around the central galaxies of dark matter haloes is well
described by a Sersic profile, the radial scale and amplitude of which vary
systematically with halo mass (M_200). The total stellar mass surface density
profile breaks at the radius where accreted stars start to dominate over stars
formed in the galaxy itself. This break disappears with increasing M_200
because accreted stars contribute more of the total mass of galaxies, and is
less distinct when the same galaxies are averaged in bins of stellar mass,
because of scatter in the relation between M_star and M_200. To test our model
we have derived average stellar mass surface density profiles for massive
galaxies at z~0.08 by stacking SDSS images. Our model agrees well with these
stacked profiles and with other data from the literature, and makes predictions
that can be more rigorously tested by future surveys that extend the analysis
of the outer structure of galaxies to fainter isophotes. We conclude that it is
likely that the outer structure of the spheroidal components of galaxies is
largely determined by collisionless merging during their hierarchical assembly


title:
Herschel Exploitation of Local Galaxy Andromeda (HELGA) III: The Star
  Formation Law in M31

abstract:
  We present a detailed study of how the Star Formation Rate (SFR) relates to
the interstellar medium (ISM) of M31 at ~140pc scales. The SFR is calculated
using the far-ultraviolet and 24um emission, corrected for the old stellar
population in M31. We find a global value for the SFR of 0.25+/-0.05Msun/yr and
compare this with the SFR found using the total far-infrared (FIR) luminosity.
There is general agreement in regions where young stars dominate the dust
heating. Atomic hydrogen (HI) and molecular gas (traced by carbon monoxide, CO)
or the dust mass is used to trace the total gas in the ISM. We show that the
global surface densities of SFR and gas mass place M31 amongst a set of low-SFR
galaxies in the plot of Kennicutt (1998b). The relationship between SFR and gas
surface density is tested in six radial annuli across M31, assuming a power law
relationship with index, N. The star formation law using total gas traced by HI
and CO gives a global index of N=2.03+/-0.04, with a significant variation with
radius; the highest values are observed in the 10kpc ring. We suggest that this
slope is due to HI turning molecular at ~10Msun/pc2. When looking at H2
regions, we measure a higher mean SFR suggesting a better spatial correlation
between H2 and SF. We find N~0.6 with consistent results throughout the disk -
this is at the low end of values found in previous work and argues against a
superlinear SF law on small scales.


title:
Nonlinear Color-Metallicity Relations of Globular Clusters. IV. Testing
  the Nonlinearity Scenario for Color Bimodality via HST/WFC3 u-band Photometry
  of M84 (NGC 4374)

abstract:
  Color distributions of globular clusters (GCs) in most massive galaxies are
bimodal. Assuming linear color-to-metallicity conversions, bimodality is viewed
as the presence of merely two GC subsystems with distinct metallicities, which
serves as a critical backbone of various galaxy formation theories. Recent
studies, however, revealed that the color-metallicity relations (CMRs) often
used to derive GC metallicities (e.g., CMRs of g-z, V-I and C-T1) are in fact
inflected. Such inflection can create bimodal color distributions if the
underlying GC metallicity spread is simply broad as expected from the
hierarchical merging paradigm of galaxy formation. In order to test the
nonlinear-CMR scenario for GC color bimodality, the u-band photometry is
proposed because the u-related CMRs (e.g., CMRs of u-g and u-z) are
theoretically predicted to be least inflected and most distinctive among
commonly used optical CMRs. Here, we present Hubble Space Telescope (HST)/WFC3
F336W (u-band) photometry of the GC system in M84, a giant elliptical in the
Virgo galaxy cluster. Combining the u data with the existing HST ACS/WFC g and
z data, we find that the u-z and u-g color distributions are different from the
g-z distribution in a very systematic manner and remarkably consistent with our
model predictions based on the nonlinear-CMR hypothesis. The results lend
further confidence to validity of the nonlinear-CMR scenario as an explanation
for GC color bimodality. There are some GC systems showing bimodal
spectroscopic metallicity, and in such systems the inflected CMRs often create
stronger bimodality in the color domain.


title: What controls star formation in the central 500 pc of the Galaxy?

abstract:
  The star formation rate (SFR) in the Central Molecular Zone (CMZ, i.e. the
central 500 pc) of the Milky Way is lower by a factor of >10 than expected for
the substantial amount of dense gas it contains, which challenges current star
formation theories. In this paper, we quantify which physical mechanisms could
be responsible. On scales larger than the disc scale height, the low SFR is
found to be consistent with episodic star formation due to secular
instabilities or possibly variations of the gas inflow along the Galactic bar.
The CMZ is marginally Toomre-stable when including gas and stars, but highly
Toomre-stable when only accounting for the gas, indicating a low condensation
rate of self-gravitating clouds. On small scales, we find that the SFR in the
CMZ may be caused by an elevated critical density for star formation due to the
high turbulent pressure. The existence of a universal density threshold for
star formation is ruled out. The HI-H$_2$ phase transition of hydrogen, the
tidal field, a possible underproduction of massive stars due to a bottom-heavy
initial mass function, magnetic fields, and cosmic ray or radiation pressure
feedback also cannot individually explain the low SFR. We propose a
self-consistent cycle of star formation in the CMZ, in which the effects of
several different processes combine to inhibit star formation. The
rate-limiting factor is the slow evolution of the gas towards collapse - once
star formation is initiated it proceeds at a normal rate. The ubiquity of star
formation inhibitors suggests that a lowered central SFR should be a common
phenomenon in other galaxies. We discuss the implications for galactic-scale
star formation and supermassive black hole growth, and relate our results to
the star formation conditions in other extreme environments.


title: Dark matter halo properties from galaxy-galaxy lensing

abstract:
  We present results for a galaxy-galaxy lensing study based on imaging data
from the Canada-France-Hawaii Telescope Legacy Survey Wide. From a 12 million
object multi-colour catalogue for 124 deg^2 of photometric data in the
u*g'r'i'z' filters we compute photometric redshifts (with a scatter of
\sigma_{\Delta z/(1+z)} = 0.033 and an outlier rate of \eta=2.0 per cent for
i'<=22.5) and extract galaxy shapes down to i'=24.0. We select a sample of
lenses and sources with 0.05 < z_d <= 1 and 0.05 < z_s <= 2. We fit three
different galaxy halo profiles to the lensing signal, a singular isothermal
sphere (SIS), a truncated isothermal sphere (BBS) and a universal density
profile (NFW). We derive velocity dispersions by fitting an SIS out to 100
h^{-1} kpc to the excess surface mass density \Delta\Sigma and perform maximum
likelihood analyses out to a maximum scale of 2 h^{-1} Mpc to obtain halo
parameters and scaling relations. We find luminosity scaling relations of
\sigma_{red} ~ L^{0.24+-0.03} for the red lens sample, \sigma_{blue} ~
L^{0.23+-0.03} for blue lenses and \sigma ~ L^{0.29+-0.02} for the combined
lens sample with zeropoints of \sigma*_{red}=162+-2 km/s, \sigma*_{blue}=115+-3
km/s and \sigma*=135+-2 km/s at a chosen reference luminosity L*_{r'} = 1.6
\times 10^10 h^{-2} L_{r',sun}. The steeper slope for the combined sample is
due to the different zeropoints of the blue and red lenses and the fact that
blue lenses dominate at low luminosities and red lenses at high luminosities.
The mean effective redshifts for the lens samples are <z_{red}>=0.28 for red
lenses, <z_{blue}>=0.35 for blue lenses and <z>=0.34 for the combined lens
sample.


title:
A signature of quantum spin liquids in superconductors with topological
  order

abstract:
  This paper has been withdrawn and superseded by a new version entitled
"Singularity of the London penetration depth at quantum critical points in
superconductors" by Debanjan Chowdhury, Brian Swingle, Erez Berg and Subir
Sachdev, posted in arXiv:1305.2918. The more recent paper has a number of new
interesting results and includes a comprehensive analysis of 3 different
classes of QCPs, including the one that was originally considered.


title: Moduli space of supersymmetric QCD in the Veneziano limit

abstract:
  We study the moduli space of 4d N=1 supersymmetric QCD in the Veneziano limit
using Hilbert series. In this limit, the numbers of colours and flavours are
taken to be large with their ratio fixed. It is shown that the Hilbert series,
which is a partition function of an ensemble of gauge invariant quantities
parametrising the moduli space, can also be realised as a partition function of
a system of interacting Coulomb gas in two dimensions. In the electrostatic
equilibrium, exact and asymptotic analyses reveal that such a system exhibits
two possible phases. Physical quantities, such as charge densities, free
energies, and Hilbert series, associated with each phase, are computed
explicitly and discussed in detail. We then demonstrate the existence of the
third order phase transition in this system.


title:
Andromeda Optical and Infrared Disk Survey I. New Insights in Wide-Field
  Near-IR Surface Photometry

abstract:
  We present wide-field near-infrared J and Ks images of the Andromeda Galaxy
taken with WIRCam on the Canada-France-Hawaii Telescope (CFHT) as part of the
Andromeda Optical and Infrared Disk Survey (ANDROIDS). This data set allows
simultaneous observations of resolved stars and NIR surface brightness across
M31's entire bulge and disk (within R=22 kpc). The primary concern of this work
is the development of NIR observation and reduction methods to recover a
uniform surface brightness map across the 3x1 degree disk of M31. This
necessitates sky-target nodding across 27 WIRCam fields. Two sky-target nodding
strategies were tested, and we find that strictly minimizing sky sampling
latency does not maximize sky subtraction accuracy, which is at best 2% of the
sky level. The mean surface brightness difference between blocks in our mosaic
can be reduced from 1% to 0.1% of the sky brightness by introducing scalar sky
offsets to each image. The true surface brightness of M31 can be known to
within a statistical zeropoint of 0.15% of the sky level (0.2 mag arcsec sq.
uncertainty at R=15 kpc). Surface brightness stability across individual WIRCam
frames is limited by both WIRCam flat field evolution and residual sky
background shapes. To overcome flat field variability of order 1% over 30
minutes, we find that WIRCam data should be calibrated with real-time sky
flats. Due either to atmospheric or instrumental variations, the individual
WIRCam frames have typical residual shapes with amplitudes of 0.2% of the sky
after real-time flat fielding and median sky subtraction. We present our WIRCam
reduction pipeline and performance analysis here as a template for future
near-infrared observers needing wide-area surface brightness maps with
sky-target nodding, and give specific recommendations for improving photometry
of all CFHT/WIRCam programs. (Abridged)


title: Hadroproduction of t anti-t pair with a b anti-b pair with PowHel

abstract:
  We simulate the hadroproduction of a top-antitop pair in association with a
bottom-antibottom pair at 14 TeV LHC using the PowHel package. We use the
generated events, stored according to the Les-Houches event format, to make
predictions for differential distributions formally at the next-to-leading
order (NLO) accuracy and we compare these to existing predictions accurate at
NLO.


title: Lattice QCD in rotating frames

abstract:
  We formulate lattice QCD in rotating frames to study the physics of QCD
matter under rotation. We construct the lattice QCD action with the rotational
metric and apply it to the Monte Carlo simulation. As the first application, we
calculate the angular momenta of gluons and quarks in the rotating QCD vacuum.
This new framework is useful to analyze various rotation-related phenomena in
QCD.


title:
Nonlinear Color-Metallicity Relations of Globular Clusters. V. Nonlinear
  Absorption-line Index versus Metallicity Relations and Bimodal Index
  Distributions of M31 Globular Clusters

abstract:
  Recent spectroscopy on the globular cluster (GC) system of M31 with
unprecedented precision witnessed a clear bimodality in absorption-line index
distributions of old GCs. Such division of extragalactic GCs, so far asserted
mainly by photometric color bimodality, has been viewed as the presence of
merely two distinct metallicity subgroups within individual galaxies and forms
a critical backbone of various galaxy formation theories. Given that
spectroscopy is a more detailed probe into stellar population than photometry,
the discovery of index bimodality may point to the very existence of dual GC
populations. However, here we show that the observed spectroscopic dichotomy of
M31 GCs emerges due to the nonlinear nature of metallicity-to-index conversion
and thus one does not necessarily have to invoke two separate GC subsystems. We
take this as a close analogy to the recent view that metallicity-color
nonlinearity is primarily responsible for observed GC color bimodality. We also
demonstrate that the metallicity-sensitive magnesium line displays
non-negligible metallicity-index nonlinearity and Balmer lines show rather
strong nonlinearity. This gives rise to bimodal index distributions, which are
routinely interpreted as bimodal metallicity distributions, not considering
metallicity-index nonlinearity. Our findings give a new insight into the
constitution of M31's GC system, which could change much of the current thought
on the formation of GC systems and their host galaxies.


title:
An overview of (selected) recent results in finite-temperature lattice
  QCD

abstract:
  I discuss recent results on lattice QCD calculations with the main emphasis
on the thermodynamics of the crossover region, restoration of the chiral
symmetry and fluctuations of conserved charges as indicator of deconfinement,
that may also be used to determine the chemical freeze-out conditions in
heavy-ion collision experiments.


title:
Elementary Excitations due to Orbital Degrees of Freedom in Iron Based
  Superconductors

abstract:
  One central issue under intense debate in the study of the iron based
superconductors is the origin of the structural phase transition that changes
the crystal lattice symmetry from tetragonal to orthorhombic. This structural
phase transition, occurring universally in almost every family of the
iron-based superconductors, breaks the lattice $C_4$ rotational symmetry and
results in an anisotropy in a number of physical properties. Due to the unique
topology of the Fermi surface, both orbital- and spin-based scenarios have been
proposed as the driving force. In this review, we focus on theories from the
orbital-based scenario and discuss several related experiments. It is pointed
out that although both scenarios lead to the same macroscopic phases and are
not distinguishable in bulk measurements of the thermodynamic properties, the
elementary excitations could be fundamentally different, and provide us with
the possibility to resolve this long-standing debate between orbital- and
spin-based theories.


title: A Variant of the Gr\"obner Basis Algorithm for Computing Hilbert Bases

abstract:
  Gr\"obner bases can be used for computing the Hilbert basis of a numerical
submonoid. By using these techniques, we provide an algorithm that calculates a
basis of a subspace of a finite-dimensional vector space over a finite prime
field given as a matrix kernel.


title: Tetramerization in a SU(4)-Heisenberg model on the honeycomb lattice

abstract:
  The SU(4) Heisenberg model can serve as a low energy model of the Mott
insulating state in materials where the spins and orbitals are highly
symmetric, or in systems of alkaline-earth atoms on optical lattice. Recently,
it has been argued that on the honeycomb lattice the model exhibits a unique
spin-orbital liquid phase with an algebraic decay of correlations [P. Corboz et
al., Phys. Rev. X 2, 041013 (2012)]. Here we study the instability of the
algebraic spin-orbital liquid toward spontaneous formation of SU(4) singlet
plaquettes (tetramerization). Using a variational Monte Carlo approach to
evaluate the projected wave-function of fermions with $\pi$-flux state, we find
that the algebraic liquid is robust, and that a finite value of the next
nearest exchange is needed to induce tetramerization. We also studied the phase
diagram of a model which interpolates between the nearest neighbor Heisenberg
model and a Hamiltonian for which the singlet-plaquette product state is an
exact ground state.


title:
Extracting equation of state parameters from black hole-neutron star
  mergers: aligned-spin black holes and a preliminary waveform model

abstract:
  Information about the neutron-star equation of state is encoded in the
waveform of a black hole-neutron star system through tidal interactions and the
possible tidal disruption of the neutron star. During the inspiral this
information depends on the tidal deformability Lambda of the neutron star, and
we find that Lambda is the best measured parameter during the merger and
ringdown as well. We performed 134 simulations where we systematically varied
the equation of state as well as the mass ratio, neutron star mass, and aligned
spin of the black hole. Using these simulations we have developed an analytic
representation of the full inspiral-merger-ringdown waveform calibrated to
these numerical waveforms, and we use this analytic waveform to estimate the
accuracy to which Lambda can be measured with gravitational-wave detectors. We
find that although the inspiral tidal signal is small, coherently combining
this signal with the merger-ringdown matter effect improves the measurability
of Lambda by a factor of ~3 over using just the merger-ringdown matter effect
alone. However, incorporating correlations between all the waveform parameters
then decreases the measurability of Lambda by a factor of ~3. The uncertainty
in Lambda increases with the mass ratio, but decreases as the black hole spin
increases. Overall, a single Advanced LIGO detector can measure Lambda for mass
ratios Q = 2--5, black hole spins J_BH/M_BH^2 = -0.5--0.75, neutron star masses
M_NS = 1.2M_sun--1.45M_sun, and an optimally oriented distance of 100Mpc to an
uncertainty of ~10%--100%. For the proposed Einstein Telescope, the uncertainty
in Lambda is an order of magnitude smaller.


title:
Analytic Wavefunctions for Collective Modes in Fractional Quantum Hall
  Fluids

abstract:
  We show model wavefunctions for neutral collective modes in fractional
quantum Hall (FQH) states have simple analytic forms obtained from judicially
reducing the powers of selected pairs in the ground state Jastrow factor. This
scheme of "pair excitations" works for the magneto-roton modes of
single-component Abelian and non-Abeliean FQH states, as well as neutral
fermion mode for the Moore-Read (MR) state. The analytic wavefunctions enable
computations in the thermodynamic limit previous inaccessible to numerics, and
the long wavelength limit of the neutral energy gap of the magneto-roton modes
can be interpreted as fusion of charges in two-dimensional plasma picture,
extending the plasma analogy to neutral excitations. A lattice diagrammatic
method of representing these many-body wavefunctions and FQH elementary
excitations is also presented.


title: Cavitation effects on the confinement/deconfinement transition

abstract:
  Cavitation is a process where the viscous terms in a relativistic fluid
result in reducing the effective pressure, thus facilitating the nucleation of
bubbles of a stable phase. The effect is particularly pronounced in the
vicinity of a (weak) first-order phase transition. We use the holographic
correspondence to study cavitation in a strongly coupled planar cascading gauge
theory plasma close to the confinement/deconfinement phase transition. While in
this particular model the shift of the deconfinement temperature due to
cavitation does not exceed 5%, we speculate that cavitation might be important
near the QCD critical point.


title: Characteristics of magnetoacoustic sausage modes

abstract:
  Aims: We perform an advanced study of the fast magnetoacoustic sausage
oscillations of coronal loops in the context of MHD coronal seismology to
establish the dependence of the sausage mode period and cut-off wavenumber on
the plasma-beta of the loop-filling plasma. A parametric study of the ratios
for different harmonics of the mode is also carried out.
  Methods: Full magnetohydrodynamic numerical simulations were performed using
Lare2d, simulating hot, dense loops in a magnetic slab environment. The
symmetric Epstein profile and a simple step-function profile were both used to
model the density structure of the simulated loops. Analytical expressions for
the cut-off wavenumber and the harmonic ratio between the second longitudinal
harmonic and the fundamental were also examined.
  Results: It was established that the period of the global sausage mode is
only very weakly dependent on the value of the plasma-beta inside a coronal
loop, which justifies the application of this model to hot flaring loops. The
cut-off wavenumber kc for the global mode was found to be dependent on both
internal and external values of the plasma-beta, again only weakly. By far the
most important factor in this case was the value of the density contrast ratio
between the loop and the surroundings. Finally, the deviation of the harmonic
ratio P1/2P2 from the ideal non-dispersive case was shown to be considerable at
low k, again strongly dependent on plasma density. Quantifying the behaviour of
the cut-off wavenumber and the harmonic ratio has significant applications to
the field of coronal seismology.


title:
Dark plasmons in hot spot generation and polarization in interelectrode
  nanoscale junctions

abstract:
  Nanoscale gaps between adjacent metallic nanostructures give rise to
extraordinarily large field enhancements, known as "hot spots", upon
illumination. Incident light with the electric field polarized across the gap
(along the interparticle axis) is generally known to induce the strongest
surface enhanced Raman spectroscopy (SERS) enhancements. However, here we show
that for a nanogap located within a nanowire linking extended Au electrodes,
the greatest enhancement and resulting SERS emission occurs when the electric
field of the incident light is polarized along the gap (transverse to the
interelectrode axis). This surprising and counterintuitive polarization
dependence results from a strong dipolar plasmon mode that resonates
transversely across the nanowire, coupling with dark multipolar modes arising
from subtle intrinsic asymmetries in the nanogap. These modes give rise to
highly reproducible SERS enhancements at least an order of magnitude larger
than the longitudinal modes in these structures.


title:
Solar Cycle Variability and Surface Differential Rotation from Ca II
  K-Line Time Series Data

abstract:
  Analysis of over 36 years of time series data from the NSO/AFRL/Sac Peak
K-line monitoring program elucidates five components of the variation of the
seven measured chromospheric parameters: (a) the solar cycle (period ~ 11
years), (b) quasi-periodic variations (periods ~100 days), (c) a broad band
stochastic process (wide range of periods), (d) rotational modulation, and (e)
random observational errors, independent of (a)-(d). Correlation and power
spectrum analyses elucidate periodic and aperiodic variation of these
parameters. Time-frequency analysis illuminates periodic and quasi periodic
signals, details of frequency modulation due to differential rotation, and in
particular elucidates the rather complex harmonic structure (a) and (b) at time
scales in the range ~0.1 - 10 years. These results using only full-disk data
suggest that similar analyses will be useful at detecting and characterizing
differential rotation in stars from stellar light-curves such as thosebeing
produced by NASA's Kepler observatory. Component (c) consists of variations
over a range of timescales, in the manner of a 1/f random process with a
power-law slope index that varies in a systematic way. A time-dependent
Wilson-Bappu effect appears to be present in the solar cycle variations (a),
but not in the more rapid variations of the stochastic process (c). Component
(d) characterizes differential rotation of the active regions. Component (e) is
of course not characteristic of solar variability, but the fact that the
observational errors are quite small greatly facilitates the analysis of the
other components. The data analyzed in this paper can be found at the National
Solar Observatory web site http://nsosp.nso.edu/cak_mon/, or by file transfer
protocol at ftp://ftp.nso.edu/idl/cak.parameters


title: Rapid mixing implies exponential decay of correlations

abstract:
  We provide an analysis of the correlation properties of spin and fermionic
systems on a lattice evolving according to open system dynamics generated by a
local primitive Liouvillian. We show that if the Liouvillian has a spectral gap
which is independent of the system size, then the correlations between local
observables decay exponentially as a function of the distance between their
supports. We prove, furthermore, that if the Log-Sobolev constant is
independent of the system size, then the system satisfies clustering of
correlations in the mutual information - a much more stringent form of
correlation decay. As a consequence, in the latter case we get an area law
(with logarithmic corrections) for the mutual information. As a further
corollary, we obtain a stability theorem for local distant perturbations. We
also demonstrate that gapped free-fermionic systems exhibit clustering of
correlations in the covariance and in the mutual information. We conclude with
a discussion of the implications of these results for the classical simulation
of open quantum systems with matrix-product operators and the robust
dissipative preparation of topologically ordered states of lattice spin
systems.


title:
Effect of direct CP violation in charm on gamma extraction from B->DK,
  D->K0Spi+pi- Dalitz plot analysis

abstract:
  A possible effect of direct CP violation in D->K0Spipi decay on the gamma
measurement from B->DK, D->K0Spi+pi- Dalitz plot analysis is considered.
Systematic uncertainty of gamma coming from the current limits on direct CP
violation in D->K0Spi+pi- is estimated, and a modified model-independent
procedure of B->DK, D->K0Spi+pi- Dalitz plot analysis is proposed that gives an
unbiased gamma measurement even in presence of direct CP violation in charm
decays. The technique is applicable to other three-body D decays such as
D->K0SK+K-, D->pi+pi-pi0, etc.


title:
Comment on "Calculation of microcanonical entropy differences from
  configurational averages"

abstract:
  We introduce a simple improvement on the method to calculate equilibrium
entropy differences between classical energy levels proposed by Davis (S.
Davis, Phys. Rev. E, 050101, 2011). We demonstrate that the modification is
superior to the original whenever the energy levels are sufficiently closely
spaced or whenever the microcanonical averaging needed in the method is carried
out by importance sampling Monte Carlo. We also point out the necessary
adjustments if Davis's method (improved or not) is to be used with molecular
dynamics simulations.


title:
Helioseismology of sunspots: how sensitive are travel times to the
  Wilson depression and to the subsurface magnetic field?

abstract:
  In order to assess the ability of helioseismology to probe the subsurface
structure and magnetic field of sunspots, we need to determine how helioseismic
travel times depend on perturbations to sunspot models. Here we numerically
simulate the propagation of f, p1, and p2 wave packets through magnetic sunspot
models. Among the models we considered, a ~50 km change in the height of the
Wilson depression and a change in the subsurface magnetic field geometry can
both be detected above the observational noise level. We also find that the
travel-time shifts due to changes in a sunspot model must be modeled by
computing the effects of changing the reference sunspot model, and not by
computing the effects of changing the subsurface structure in the quiet-Sun
model. For p1 modes the latter is wrong by a factor of four. In conclusion,
numerical modeling of MHD wave propagation is an essential tool for the
interpretation of the effects of sunspots on seismic waveforms.


title:
A 420 day X-ray/optical modulation and extended X-ray dips in the
  short-period transient Swift J1753.5-0127

abstract:
  We have discovered a \sim420d modulation, with associated X-ray dips, in
RXTE-ASM/MAXI/Swift-BAT archival light-curves of the short-period (3.2h)
black-hole X-ray transient, Swift J1753.5-0127. This modulation only appeared
at the end of a gradual rebrightening, approximately 3 years after the initial
X-ray outburst in mid-2005. The same periodicity is present in both the 2-20
keV and 15-50 keV bands, but with a \sim0.1 phase offset (\sim40d).
Contemporaneous photometry in the optical and near-IR reveals a weaker
modulation, but consistent with the X-ray period. There are two substantial
X-ray dips (very strong in the 15-50 keV band, weaker at lower energies) that
are separated by an interval equal to the X-ray period. This likely indicates
two physically separated emitting regions for the hard X-ray and lower energy
emission. We interpret this periodicity as a property of the accretion disc,
most likely a long-term precession, where the disc edge structure and X-ray
irradiation is responsible for the hard X-ray dips and modulation, although we
discuss other possible explanations, including Lense-Thirring precession in the
inner disc region and spectral state variations. Such precession indicates a
very high mass ratio LMXB, which even for a \sim10M_sun BH requires a brown
dwarf donor (\sim0.02M_sun), making Swift J1753.5-0127 a possible analogue of
millisecond X-ray pulsars.We compare the properties of Swift J1753.5-0127 with
other recently discovered short-period transients, which are now forming a
separate population of high latitude BH transients located in the galactic
halo.


title:
The relationship between hard X-ray pulse timings and the locations of
  footpoint sources during solar flares

abstract:
  The cause of quasi-periodic pulsations (QPP) in solar flares remains the
subject of debate. Recently, Nakariakov & Zimovets (2011) proposed a new model
suggesting that, in two-ribbon flares, such pulsations could be explained by
propagating slow waves. These waves may travel obliquely to the magnetic field,
reflect in the chromosphere and constructively interfere at a spatially
separate site in the corona, leading to quasi-periodic reconnection events
progressing along the flaring arcade. Such a slow wave regime would have
certain observational characteristics. We search for evidence of this
phenomenon during a selection of two-ribbon flares observed by RHESSI, SOHO and
TRACE; the flares of 2002 November 9, 2005 January 19 and 2005 August 22. We
were not able to observe a clear correlation between hard X-ray footpoint
separations and pulse timings during these events. Also, the motion of hard
X-ray footpoints is shown to be continuous within the observational error,
whereas a discontinuous motion might be anticipated in the slow wave model.
Finally, we find that for a preferential slow wave propagation angle of 25-28
degrees that is expected for the fastest waves, the velocities of the hard
X-ray footpoints lead to estimated pulse periods and ribbon lengths
significantly larger than the measured values. Hence, for the three events
studied, we conclude that the observational characteristics cannot be easily
explained via the Nakariakov & Zimovets (2011) propagating slow wave model when
only angles of 25-28 degrees are considered. We provide suggested flare
parameters to optimise future studies of this kind.


title: A hybrid bat algorithm

abstract:
  Swarm intelligence is a very powerful technique to be used for optimization
purposes. In this paper we present a new swarm intelligence algorithm, based on
the bat algorithm. The Bat algorithm is hybridized with differential evolution
strategies. Besides showing very promising results of the standard benchmark
functions, this hybridization also significantly improves the original bat
algorithm.


title: Principle "synthesis" for the solution of tasks of class NP

abstract:
  Initial contours of the non-standard approach to reception of the answer of
any task on discrete structures are considered: the algorithm independently
creates such answer from separate fragments.


title:
Bifurcation of periodic solutions from a ring configuration in the
  vortex and filament problems

abstract:
  This paper gives an analysis of the movement of n+1 almost parallel filaments
or vortices. Starting from a polygonal equilibrium of n vortices with equal
circulation and one vortex at the center of the polygon, we find bifurcation of
periodic solutions. The bifurcation result makes use of the orthogonal degree
in order to prove global bifurcation of periodic solutions depending on the
circulation of the central vortex. In the case of the filament problem these
solutions are periodic traveling waves.


title:
Transitional disks and their origins: an infrared spectroscopic survey
  of Orion A

abstract:
  Transitional disks are protoplanetary disks around young stars, with inner
holes or gaps which are surrounded by optically thick outer, and often inner,
disks. Here we present observations of 62 new transitional disks in the Orion A
star-forming region. These were identified using the \textit{Spitzer Space
Telescope}'s Infrared Spectrograph and followed up with determinations of
stellar and accretion parameters using the Infrared Telescope Facility's SpeX.
We combine these new observations with our previous results on transitional
disks in Taurus, Chamaeleon I, Ophiuchus and Perseus, and with archival X-ray
observations. This produces a sample of 105 transitional disks of "cluster" age
3 Myr or less, by far the largest hitherto assembled. We use this sample to
search for trends between the radial structure in the disks and many other
system properties, in order to place constraints on the possible origins of
transitional disks. We see a clear progression of host star accretion rate and
the different disk morphologies. We confirm that transitional disks with
complete central clearings have median accretion rates an order of magnitude
smaller than radially continuous disks of the same population. Pre-transitional
disks --- those objects with gaps that separate inner and outer disks --- have
median accretion rates intermediate between the two. Our results from the
search for statistically significant trends, especially related to $\dot{M}$,
strongly support that in both cases the gaps are far more likely to be due to
the gravitational influence of Jovian planets or brown dwarfs orbiting within
the gaps, than to any of the photoevaporative, turbulent or grain-growth
processes that can lead to disk dissipation. We also find that the fraction of
Class II YSOs which are transitional disks is large, 0.1-0.2, especially in the
youngest associations.


title: Numerical model of elastic laminated glass beams under finite strain

abstract:
  Laminated glass structures are formed by stiff layers of glass connected with
a compliant plastic interlayer. Due to their slenderness and heterogeneity,
they exhibit a complex mechanical response that is difficult to capture by
single-layer models even in the elastic range. The purpose of this paper is to
introduce an efficient and reliable finite element approach to the simulation
of the immediate response of laminated glass beams. It proceeds from a refined
plate theory due to Mau (1973), as we treat each layer independently and
enforce the compatibility by the Lagrange multipliers. At the layer level, we
adopt the finite-strain shear deformable formulation of Reissner (1972) and the
numerical framework by Ibrahimbegovi\'{c} and Frey (1993). The resulting system
is solved by the Newton method with consistent linearization. By comparing the
model predictions against available experimental data, analytical methods and
two-dimensional finite element simulations, we demonstrate that the proposed
formulation is reliable and provides accuracy comparable to the detailed
two-dimensional finite element analyzes. As such, it offers a convenient basis
to incorporate more refined constitutive description of the interlayer.


title:
Gregarious vs Individualistic Behavior in Vicsek Swarms and the Onset of
  First-Order Phase Transitions

abstract:
  The Standard Vicsek Model (SVM) is a minimal nonequilibrium model of
self-propelled particles that appears to capture the essential ingredients of
critical flocking phenomena. In the SVM, particles tend to align with each
other and form ordered flocks of collective motion; however, perturbations
controlled by a noise term lead to a noise-driven, continuous order-disorder
phase transition. In this work, we extend the SVM by introducing a parameter
$\alpha$ that allows particles to be individualistic instead of gregarious,
i.e. to choose a direction of motion independently of their neighbors. By
focusing on the small-noise regime, we show that a relatively small probability
of individualistic motion (around 10%) is sufficient to drive the system from a
Vicsek-like ordered phase to a disordered phase. Despite the fact that the
$\alpha-$extended Model preserves the O(n) symmetry, the interaction range, as
well as the dimensionality of the underlying SVM, this novel phase transition
is found to be discontinuous (first-order), an intriguing manifestation of the
richness of the nonequilibrium flocking/swarming phenomenon.


title:
A stable numerical scheme for stochastic differential equations with
  multiplicative noise

abstract:
  We introduce a new approach for designing numerical schemes for stochastic
differential equations (SDEs). The approach, which we have called direction and
norm decomposition method, proposes to approximate the required solution $X_t$
by integrating the system of coupled SDEs that describes the evolution of the
norm of $X_t$ and its projection on the unit sphere. This allows us to develop
an explicit scheme for stiff SDEs with multiplicative noise that shows a solid
performance in various numerical experiments. Under general conditions, the new
integrator preserves the almost sure stability of the solutions for any
step-size, as well as the property of being distant from $0$. The scheme also
has linear rate of weak convergence for a general class of SDEs with locally
Lipschitz coefficients,and one-half strong order of convergence.


title: The optical counterpart of the bright X-ray transient Swift J1745-26

abstract:
  We present a 30-day monitoring campaign of the optical counterpart of the
bright X-ray transient Swift J1745-26, starting only 19 minutes after the
discovery of the source. We observe the system peaking at i' ~17.6 on day 6
(MJD 56192) to then decay at a rate of ~0.04 mag/day. We show that the optical
peak occurs at least 3 days later than the hard X-ray (15-50 keV) flux peak.
Our measurements result in an outburst amplitude greater than 4.3 magnitudes,
which favours an orbital period < 21 h and a companion star with a spectral
type later than ~ A0. Spectroscopic observations taken with the GTC-10.4 m
telescope reveal a broad (FWHM ~ 1100 km/s), double-peaked H_alpha emission
line from which we constrain the radial velocity semi-amplitude of the donor to
be K_2 > 250 km/s. The breadth of the line and the observed optical and X-ray
fluxes suggest that Swift J1745-26 is a new black hole candidate located closer
than ~7 kpc.


title: On odd unitary Steinberg group

abstract:
  Let $R$ be a ring with pseudo-involution, $\mathfrak L$ be an odd form
parameter, $\mathrm U(2n,\,R,\,\mathfrak L)$ be an odd hyperbolic unitary
group, $\mathrm{EU}(2n,\,R,\,\mathfrak L)$ be it elementary subgroup and
$\mathrm{StU}(2n,\,R,\,\mathfrak L)$ be an odd unitary Steinberg group. We
compute the Schur multipliers of $\mathrm{StU}(2n,\,R,\,\mathfrak L)$ and
$\mathrm{EU}(R,\,\mathfrak L)$.


title:
Global bifurcation of planar and spatial periodic solutions from the
  polygonal relative equilibria for the n-body problem

abstract:
  Given $n$ point masses turning in a plane at a constant speed, this paper
deals with the global bifurcation of periodic solutions for the masses, in that
plane and in space. As a special case, one has a complete study of n identical
masses on a regular polygon and a central mass. The symmetries of the problem
are used in order to find the irreducible representations, the linearization,
and with the help of the orthogonal degree theory, all the symmetries of the
bifurcating branches.


title: Three-dimensional Accelerating Electromagnetic Waves

abstract:
  We present a general theory of three-dimensional nonparaxial
spatially-accelerating waves of the Maxwell equations. These waves constitute a
two-dimensional structure exhibiting shape-invariant propagation along
semicircular trajectories. We provide classification and characterization of
possible shapes of such beams, expressed through the angular spectra of
parabolic, oblate and prolate spheroidal fields. Our results facilitate the
design of accelerating beams with novel structures, broadening scope and
potential applications of accelerating beams.

categories: physics.optics cond-mat.mes-hall math-ph math.MP