title: Optimal embeddings by unbiased shifts of Brownian motion

abstract:
  An unbiased shift of the two-sided Brownian motion $(B_t \colon t\in{\mathbb
R})$ is a random time $T$ such that $(B_{T+t} \colon t\in{\mathbb R})$ is still
a two-sided Brownian motion. Given a pair $\mu, \nu$ of orthogonal probability
measures, an unbiased shift $T$ solves the embedding problem, if $B_0\sim\mu$
implies $B_{T}\sim\nu$. A solution to this problem was given by Last et al.
(2014), based on earlier work of Bertoin and Le Jan (1992), and Holroyd and
Liggett (2001). In this note we show that this solution minimises ${\mathbb E}
\psi(T)$ over all nonnegative unbiased solutions $T$, simultaneously for all
nonnegative, concave functions $\psi$. Our proof is based on a discrete
concavity inequality that may be of independent interest.


title: Sub-Riemannian curvature of Carnot groups with rank-two distributions

abstract:
  The notion of curvature discussed in this paper is a far going generalization
of the Riemannian sectional curvature. It was first introduced by Agrachev,
Barilari and Rizzi in arXiv:1306.5318, and it is defined for a wide class of
optimal control problems: a unified framework including geometric structures
such as Riemannian, sub-Riemannian, Finsler, and sub-Finsler structures. In
this work we study the generalized sectional curvature of Carnot groups with
rank-two distributions. In particular, we consider the Cartan group and Carnot
groups with horizontal distribution of Goursat-type. In these Carnot groups we
characterize ample and equiregular geodesics. For Carnot groups with horizontal
Goursat distribution we show that their generalized sectional curvatures depend
only on the Engel part of the distribution. This family of Carnot groups
contains naturally the three-dimensional Heisenberg group, as well as the Engel
group. Moreover, we also show that in the Engel and Cartan groups there exist
initial covectors for which there is an infinite discrete set of times at which
the corresponding ample geodesics are not equiregular.


title: Event ontology in quantum mechanics and downward causation

abstract:
  We show that several interpretations of quantum mechanics admit an ontology
of objects and events. This ontology reduces the breach between mind and
matter. When humans act, their actions do not appear explainable in mechanical
terms but through mental activity: motives, desires or needs that propel them
to action. These are examples of what in the last few decades have come to be
called "downward causation". Basically, downward causation is present when the
disposition of the whole to behave in a certain way cannot be predicted from
the dispositions of the parts. The event ontology of quantum mechanics allow us
to show that systems in entangled states present emergent new properties and
downward causation.


title:
The Selection problem for discounted Hamilton-Jacobi equations: some
  non-convex cases

abstract:
  Here, we study the selection problem for the vanishing discount approximation
of non-convex, first-order Hamilton-Jacobi equations. While the selection
problem is well understood for convex Hamiltonians, the selection problem for
non-convex Hamiltonians has thus far not been studied. We begin our study by
examining a generalized discounted Hamilton-Jacobi equation. Next, using an
exponential transformation, we apply our methods to strictly quasi-convex and
to some non-convex Hamilton-Jacobi equations. Finally, we examine a non-convex
Hamiltonian with flat parts to which our results do not directly apply. In this
case, we establish the convergence by a direct approach.


title: Image modeling of compact starburst clusters: I. R136

abstract:
  Continuous progress in data quality from HST, recent multiwavelength high
resolution spectroscopy and high contrast imaging from ground adaptive optics
on large telescopes need modeling of R136 to understand its nature and
evolutionary stage. To produce the best synthesized multiwavelength images of
R136 we need to simulate the effect of dynamical and stellar evolution, mass
segregation and binary stars fraction on the survival of young massive clusters
with the initial parameters of R136 in the LMC, being set to the present
knowledge of this famous cluster. We produced a series of 32 young massive
clusters using the NBODY6 code. Each cluster was tracked with adequate temporal
samples to follow the evolution of R136 during its early stages. To compare the
NBODY6 simulations with observational data, we created the synthetic images
from the output of the code. We used the TLUSTY and KURUCZ model atmospheres to
produce the fluxes in HST/ WFPC2 filters. GENEVA isochrones were used to track
the evolution of stars. Then, we derived the observable parameters from
synthetic scenes at the spatial resolution of HST/WFPC2 in the F814W filter
(790.48nm). Surface brightness profile of the cluster, half-light radius, mass
function and neighbor radius were used to select the best representation of
R136. We compared the simulations of R136 to its HST imagery by creating
synthetic scenes at the same resolution, pixel scale and FOV of the HST. We
applied the same photometric analysis of the images as of the real ones. Having
extracted the stellar sources, we estimated the mass-function, the surface
brightness profile, the half-light radius and the neighbor radius across R136.
The interpretation of these criteria point to the fact that an initially
non-segregated cluster scenario is more representative of R136. This result
pleads for the formation of massive stars by accretion instead of collision.


title: 5-dimensional geometries II: the non-fibered geometries

abstract:
  We classify the $5$-dimensional homogeneous geometries in the sense of
Thurston. The present paper (part 2 of 3) classifies those in which the linear
isotropy representation is either irreducible or trivial. The $5$-dimensional
geometries with irreducible isotropy are the irreducible Riemannian symmetric
spaces, while those with trivial isotropy are simply-connected solvable Lie
groups of the form $\mathbb{R}^3 \rtimes \mathbb{R}^2$ or $N \rtimes
\mathbb{R}$ where $N$ is nilpotent.


title:
Degree versions of the Erdos-Ko-Rado Theorem and Erdos hypergraph
  matching conjecture

abstract:
  We use an algebraic method to prove a degree version of the celebrated Erd\H
os-Ko-Rado theorem: given $n>2k$, every intersecting $k$-uniform hypergraph $H$
on $n$ vertices contains a vertex that lies on at most $\binom{n-2}{k-2}$
edges. This result can be viewed as a special case of the degree version of a
well-known conjecture of Erd\H{o}s on hypergraph matchings. Improving the work
of Bollob\'as, Daykin, and Erd\H os from 1976, we show that given integers $n,
k, s$ with $n\ge 3k^2 s$, every $k$-uniform hypergraph $H$ on $n$ vertices with
minimum vertex degree greater than $\binom{n-1}{k-1}-\binom{n-s}{k-1}$ contains
$s$ disjoint edges.


title:
Computationally Efficient Characterization of Potential Energy Surfaces
  Based on Fingerprint Distances

abstract:
  An analysis of the network defined by the potential energy minima of
multi-atomic systems and their connectivity via reaction pathways that go
through transition states allows to understand important characteristics like
thermodynamic, dynamic and structural properties. Unfortunately computing the
transition states and reaction pathways in addition to the significant
energetically low-lying local minima is a computationally demanding task. We
here introduce a computationally efficient method that is based on a
combination of the minima hopping global optimization method and the insight
that uphill barriers tend to increase with increasing structural distances of
the educt and product states. This method allows to replace the exact
connectivity information and transition state energies with alternative and
approximate concepts. Without adding any significant additional cost to the
minima hopping global optimization approach, this method allows to generate an
approximate network of the minima, their connectivity and a rough measure for
the energy needed for their interconversion. This can be used to obtain a first
qualitative idea on important physical and chemical properties by means of a
disconnectivity graph analysis. Besides the physical insight obtained by such
an analysis, the gained knowledge can be used to make a decision if it is
worthwhile or not to invest computational resources for an exact computation of
the transition states and the reaction pathways. Furthermore it is demonstrated
that the here presented method can be used for finding physically reasonable
interconversion pathways that are promising input pathways for methods like
transition path sampling or discrete path sampling.


title:
Effect of impurity substitution on band structure and mass
  renormalization of the correlated FeTe$_{0.5}$Se$_{0.5}$ superconductor

abstract:
  Using angle-resolved photoemission spectroscopy (ARPES), we studied the
effect of the impurity potential on the electronic structure of
FeTe$_{0.5}$Se$_{0.5}$ superconductor by substituting 10\% of Ni for Fe which
leads to an electron doping of the system. We could resolve three hole pockets
near the zone center and an electron pocket near the zone corner in the case of
FeTe$_{0.5}$Se$_{0.5}$, whereas only two hole pockets near the zone center and
an electron pocket near the zone corner are resolved in the case of
Fe$_{0.9}$Ni$_{0.1}$Te$_{0.5}$Se$_{0.5}$, suggesting that the hole pocket
having predominantly the $xy$ orbital character is very sensitive to the
impurity scattering. Upon electron doping, the size of the hole pockets
decrease and the size of the electron pockets increase as compared to the host
compound. However, the observed changes in the size of the electron and hole
pockets are not consistent with the rigid-band model. Moreover, the effective
mass of the hole pockets is reduced near the zone center and of the electron
pockets is increased near the zone corner in the doped
Fe$_{0.9}$Ni$_{0.1}$Te$_{0.5}$Se$_{0.5}$ as compared to FeTe$_{0.5}$Se$_{0.5}$.
We refer these observations to the changes of the spectral function due to the
effect of the impurity potential of the dopants.


title:
Exact solution for a random walk in a time-dependent 1D random
  environment: the point-to-point Beta polymer

abstract:
  We consider the Beta polymer, an exactly solvable model of directed polymer
on the square lattice, introduced by Barraquand and Corwin. We study the
statistical properties of its point to point partition sum. The problem is
equivalent to a model of a random walk in a time-dependent (and in general
biased) 1D random environment. In this formulation, we study the sample to
sample fluctuations of the transition probability distribution function (PDF)
of the random walk. Using the Bethe ansatz we obtain exact formulas for the
integer moments, and Fredholm determinant formulas for the Laplace transform of
the directed polymer partition sum/random walk transition probability. The
asymptotic analysis of these formulas at large time $t$ is performed both (i)
in a diffusive vicinity, $x \sim t^{1/2}$, of the optimal direction (in
space-time) chosen by the random walk, where the fluctuations of the PDF are
found to be Gamma distributed; (ii) in the large deviations regime, $x \sim t$,
of the random walk, where the fluctuations of the logarithm of the PDF are
found to grow with time as $t^{1/3}$ and to be distributed according to the
Tracy-Widom GUE distribution. Our exact results complement those of BC for the
cumulative distribution function of the random walk in regime (ii), and in
regime (i) they unveil a novel fluctuation behavior. We also discuss the
crossover regime between (i) and (ii), identified as $x \sim t^{3/4}$. Our
results are confronted to extensive numerical simulations of the model.

categories: cond-mat.dis-nn cond-mat.stat-mech math-ph math.MP


title:
Creating cat states in one-dimensional quantum walks using delocalized
  initial states

abstract:
  Cat states are coherent quantum superpositions of macroscopically distinct
states and are useful for understanding the boundary between the classical and
the quantum world. Due to their macroscopic nature, cat states are difficult to
prepare in physical systems. We propose a method to create cat states in
one-dimensional quantum walks using delocalized initial states of the walker.
Since the quantum walks can be performed on any quantum system, our proposal
enables a platform-independent realization of the cat states. We further show
that the linear dispersion relation of the effective quantum walk Hamiltonian,
which governs the dynamics of the delocalized states, is responsible for the
formation of the cat states. We analyze the robustness of these states against
environmental interactions and present methods to control and manipulate the
cat states in the photonic implementation of quantum walks.


title: The ideal structure of algebraic partial crossed products

abstract:
  Given a partial action of a discrete group $G$ on a Hausdorff, locally
compact, totally disconnected topological space $X$, we consider the
correponding partial action of $G$ on the algebra $L_c(X)$ consisting of all
locally constant, compactly supported functions on $X$, taking values in a
given field $K$. We then study the ideal structure of the algebraic partial
crossed product $L_c(X)\rtimes G$. After developping a theory of induced
ideals, we show that every ideal in $L_c(X)\rtimes G$ may be obtained as the
intersection of ideals induced from isotropy groups, thus proving an algebraic
version of the Effros-Hahn conjecture.


title: Inductive supervised quantum learning

abstract:
  In supervised learning, an inductive learning algorithm extracts general
rules from observed training instances, then the rules are applied to test
instances. We show that this splitting of training and application arises
naturally, in the classical setting, from a simple independence requirement
with a physical interpretation of being non-signalling. Thus, two seemingly
different definitions of inductive learning happen to coincide. This follows
from the properties of classical information that break down in the quantum
setup. We prove a quantum de Finetti theorem for quantum channels, which shows
that in the quantum case, the equivalence holds in the asymptotic setting, that
is, for large number of test instances. This reveals a natural analogy between
classical learning protocols and their quantum counterparts, justifying a
similar treatment, and allowing to inquire about standard elements in
computational learning theory, such as structural risk minimization and sample
complexity.


title: Affinity- and topology-dependent bound on current fluctuations

abstract:
  We provide a proof of a recently conjectured universal bound on current
fluctuations in Markovian processes. This bound establishes a link between the
fluctuations of an individual observable current, the cycle affinities driving
the system into a non-equilibrium steady state, and the topology of the
network. The proof is based on a decomposition of the network into independent
cycles with both positive affinity and positive stationary cycle current. This
formalism allows for a refinement of the bound for systems in equilibrium or
with locally vanishing affinities.


title: On tea, donuts and non-commutative geometry

abstract:
  As many will agree, it feels good to complement a cup of tea by a donut or
two. This sweet relationship is also a guiding principle of non-commutative
geometry known as Serre Theorem. We explain the algebra behind this theorem and
prove that elliptic curves are complementary to the so-called non-commutative
tori.


title:
Evolutionary Stability of Polymorphic Population States in Continuous
  Games

abstract:
  In games with continuous strategy spaces, if a rest point of the replicator
dynamics is asymptotically stable then the rest point must be finitely
supported (van Veelen, M., Spreij, P., 2009. Evolution in games with a
continuous action space. Econom. Theory 39 (3), 355-376). In this article, we
address the converse question that is, we prove that a finitely supported
population state is asymptotically stable with respect to the variational norm
when it is strongly uninvadable.


title: 5-dimensional geometries I: the general classification

abstract:
  This paper is the first of a 3-part series that classifies the 5-dimensional
Thurston geometries. The present paper (part 1 of 3) summarizes the general
classification, giving the full list, an outline of the method, and some
illustrative examples. This includes phenomena that have not appeared in lower
dimensional geometries, such as an uncountable family of geometries.


title: 5-dimensional geometries III: the fibered geometries

abstract:
  We classify the 5-dimensional homogeneous geometries in the sense of
Thurston. The present paper (part 3 of 3) classifies those in which the linear
isotropy representation is nontrivial but reducible. Most of the resulting
geometries are products. Some interesting examples include a countably infinite
family of inequivalent geometries diffeomorphic to $S^3 \times S^2$; an
uncountable family in which only a countable subfamily admits compact
quotients; and the non-maximal geometry SO(4)/SO(2) realized by two distinct
maximal geometries.


title:
Momentum Analyticity of Transverse Polarization Tensor in the Normal
  Phase of a Holographic Superconductor

abstract:
  We explore the momentum analyticity of the static transverse polarization
tensor of a 2+1 dimensional holographic superconductor in its normal phase with
a nonzero chemical potential, aiming at finding the holographic counterpart of
the singularities underlying the Friedel-like oscillations of an ordinary field
theory. We prove that the polarization tensor is a meromorphic function with an
infinite number of poles located on the complex momentum plane off real axis.
With the aid of the WKB approximation these poles are found to lies
asymptotically along two straight lines parallel to the imaginary axis for a
large momentum magnitude. The similarity between the holographic Green's
function and that of an weakly coupled ordinary field theory (e.g., 2+1
dimensional QED) regarding the location of the momentum singularities offers
further support to the validity of the gauge/gravity duality.


title: Constraining the halo mass function with observations

abstract:
  The abundances of dark matter halos in the universe are described by the halo
mass function (HMF). It enters most cosmological analyses and parametrizes how
the linear growth of primordial perturbations is connected to these abundances.
Interestingly, this connection can be made approximately cosmology independent.
This made it possible to map in detail its near-universal behavior through
large-scale simulations. However, such simulations may suffer from systematic
effects, especially if baryonic physics is included. In this paper we ask how
well observations can constrain directly the HMF. The observables we consider
are galaxy cluster number counts, galaxy cluster power spectrum and lensing of
type Ia supernovae. Our results show that DES is capable of putting the first
meaningful constraints on the HMF, while both Euclid and J-PAS can give
stronger constraints, comparable to the ones from state-of-the-art simulations.
We also find that an independent measurement of cluster masses is even more
important for measuring the HMF than for constraining the cosmological
parameters, and can vastly improve the determination of the halo mass function.
Measuring the HMF could thus be used to cross-check simulations and their
implementation of baryon physics. It could even, if deviations cannot be
accounted for, hint at new physics.


title:
Experimental Freezing of mid-Evolution Fluctuations with a Programmable
  Annealer

abstract:
  For randomly selected couplers and fields, the D-Wave device typically yields
a highly Boltzmann like distribution [ indicating equilibration. These
equilibrated data however do not contain much useful information about the
dynamics which lead to equilibration. To illuminate the dynamics, special
Hamiltonians can be chosen which contain large energy barriers. In this paper
we generalize this approach by considering a class of Hamiltonians which map
clusters of spin-like qubits into 'superspins', thereby creating an energy
landscape where local minima are separated by large energy barriers. These
large energy barriers allow us to observe signatures of the transverse field
frozen. To study these systems, we assume that the these frozen spins are
describes by the Kibble-Zurek mechanism which was originally developed to
describe formation of topological defects in the early universe. It was soon
realized that it also has applications in analogous superconductor systems and
later realized to also be important for the transverse field Ising model . We
demonstrate that these barriers block equilibration and yield a non-trivial
distribution of qubit states in a regime where quantum effects are expected to
be strong, suggesting that these data should contain signatures of whether the
dynamics are fundamentally classical or quantum. We exhaustively study a class
of 3x3 square lattice superspin Hamiltonians and compare the experimental
results with those obtained by exact diagonalisation. We find that the best fit
to the data occurs at finite transverse field. We further demonstrate that
under the right conditions, the superspins can be relaxed to equilibrium,
erasing the signature of the transverse field. These results are interesting
for a number of reasons. They suggest a route to detect signatures of quantum
mechanics on the device on a statistical level.


title:
Continuum and Line Emission of Flares on Red Dwarf Stars: Origin of the
  Blue Continuum Radiation

abstract:
  There are two types of models that explain the appearance of the
quasi-blackbody radiation during the impulsive phase of stellar flares. Grinin
and Sobolev [Astrophysics, Vol. 13, 348 (1977)] argue that the blue component
of the optical continuum is formed in "the transition layer between the
chromosphere and the photosphere." Katsova et al. [Astrophysics, Vol. 17, 156
(1981)] have "raised" the source of the white-light continuum up to a dense
region in the perturbed chromosphere. In the present contribution (the main
paper is published in "Astrophysics" [Vol. 59, 475 (2016); arXiv:1710.08008],
we show that this statement in the work of Katsova et al. is erroneous.


title: Quantum incompatibility in collective measurements

abstract:
  We study the compatibility (or joint measurability) of quantum observables in
a setting where the experimenter has access to multiple copies of a given
quantum system, rather than performing the experiments on each individual copy
separately. We introduce the index of incompatibility as a quantifier of
incompatibility in this multi-copy setting, as well as the notion of
compatibility stack representing the various compatibility relations present in
a given set of observables. We then prove a general structure theorem for
multi-copy joint observables, and use it to prove that all abstract
compatibility stacks with three vertices have realizations in terms of quantum
observables.


title: Generation of a coherent electronic spin cluster in diamond

abstract:
  An obstacle for spin-based quantum sensors is magnetic noise due to proximal
spins. However, such a spin cluster surrounding the sensor can become an asset,
if it can be controlled. Here, we polarize and readout a cluster of three
nitrogen (N) electron spins coupled to a single nitrogen-vacancy (NV) spin in
diamond. We further achieve sub-nm localization of the cluster spins. Finally,
we demonstrate coherent spin exchange between the species by simultaneous
dressing of the NV and the N states. These results establish the feasibility of
environment-assisted sensing and quantum simulations with diamond spins.


title:
Bounds on short character sums and L-functions for characters with a
  smooth modulus

abstract:
  We combine a classical idea of Postnikov (1956) with the method of Korobov
(1974) for estimating double Weyl sums, deriving new bounds on short character
sums when the modulus $q$ has a small core $\prod_{p\mid q}p$. Using this
estimate, we improve certain bounds of Gallagher (1972) and Iwaniec (1974) for
the corresponding $L$-functions. In turn, this allows us to improve the error
term in the asymptotic formula for primes in short arithmetic progressions
modulo a power of a fixed prime. As yet another application of our bounds, we
substantially extend the region free of Siegel zeros.


title:
Blow-up results and soliton solutions for a generalized variable
  coefficient nonlinear Schr\"{o}dinger equation

abstract:
  In this paper, by means of similarity transformations we study exact
analytical solutions for a generalized nonlinear Schr$\ddot{\mbox{o}}$dinger
equation with variable coefficients. This equation appears in literature
describing the evolution of coherent light in a nonlinear Kerr medium,
Bose-Einstein condensates phenomena and high intensity pulse propagation in
optical fibers. By restricting the coefficients to satisfy Ermakov-Riccati
systems with multiparameter solutions, we present conditions for existence of
explicit solutions with singularities and a family of oscillating periodic
soliton-type solutions. Also, we show the existence of bright-, dark- and
Peregrine-type soliton solutions, and by means of a computer algebra system we
exemplify the nontrivial dynamics of the solitary wave center of these
solutions produced by our multiparameter approach.


title:
Competition between fermions and bosons in nuclear matter at low
  densities and finite temperatures

abstract:
  We derive the free energy for fermions and bosons from fragmentation data.
Inspired by the symmetry and pairing energy of the Weizsacker mass formula we
obtain the free energy of fermions (nucleons) and bosons (alphas and deuterons)
using Landau's free energy approach. We confirm previously obtained results for
fermions and show that the free energy for alpha particles is negative and very
close to the free energy for ideal Bose gases. Deuterons behave more similarly
to fermions (positive free energy) rather than bosons. This is due to their low
binding energy, which makes them very 'fragile', i.e., easily formed and
destroyed. We show that the {\alpha}-particle fraction is dominant at all
temperatures and densities explored in this work. This is consistent with their
negative free energy, which favors clusterization of nuclear matter into
{\alpha}-particles at subsaturation densities and finite temperatures. The role
of finite open systems and Coulomb repulsion is addressed.


title: Inflation in the closed FLRW model and the CMB

abstract:
  Recent cosmic microwave background (CMB) observations put strong constraints
on the spatial curvature via estimation of the parameter $\Omega_k$ assuming an
almost scale invariant primordial power spectrum. We study the evolution of the
background geometry and gauge-invariant scalar perturbations in an inflationary
closed FLRW model and calculate the primordial power spectrum. We find that the
inflationary dynamics is modified due to the presence of spatial curvature,
leading to corrections to the nearly scale invariant power spectrum at the end
of inflation. When evolved to the surface of last scattering, the resulting
temperature anisotropy spectrum ($C_{\ell}^{TT}$) shows deficit of power at low
multipoles ($\ell<20$). By comparing our results with the recent Planck data we
discuss the role of spatial curvature in accounting for CMB anomalies and in
the estimation of the parameter $\Omega_k$. Since the curvature effects are
limited to low multipoles, the Planck estimation of cosmological parameters
remains robust under inclusion of positive spatial curvature.


title: Cluster expansion formulas in type A

abstract:
  The aim of this paper is to give analogs of the cluster expansion formula of
Musiker and Schiffler for cluster algebras of type A with coefficients arising
from boundary arcs of the corresponding triangulated polygon. Indeed, we give
three cluster expansion formulas by perfect matchings of angles in triangulated
polygon, by discrete subsets of arrows of the corresponding ice quiver and by
minimal cuts of the corresponding quiver with potential.


title: Reinforced magnetic properties of Ni-doped BiFeO3 ceramic

abstract:
  Multiferroic materials attract considerable interest because of the wide
range of potential applications such as spintronic devices, data storage and
sensors. As a strong candidate for the applications among the limited list of
single-phase multiferroic materials, BiFeO3 (BFO) is a quite attractive
material due to its multiferroic properties at room temperature (RT). However,
BFO is widely known to have large leakage current and small spontaneous
polarization due to the existence of crystalline defects such as oxygen
vacancies. Furthermore, the magnetic moment of pure BFO is very weak owing to
its antiferromagnetic nature. In this paper, the effects of Ni2+ substitution
on the magnetic properties of bulk BFO have been investigated. BFO, and
BiFe0.99Ni0.01O3, BiFe0.98Ni0.02O3 and BiFe0.97Ni0.03O3 (BFNO: Ni-doped BFO)
ceramics were prepared by solid-state reaction and rapid sintering, and
analyzed by structural and magnetic-property measurements. The leakage current
density was measured at RT by using a standard ferroelectric tester. All the
Ni-doped BFO exhibit the similar rhombohedral perovskite structure (R3c) to
that of BFO. The magnetic properties of Ni-doped BFO are much enhanced with
respect to BFO prepared at the same conditions, since the enhanced
ferromagnetic interaction is caused by the Fe/Ni coupling.


title:
On the Capacity Regions of Single-Channel and Multi-Channel Full-Duplex
  Links

abstract:
  We study the achievable capacity regions of full-duplex links in the single-
and multi-channel cases (in the latter case, the channels are assumed to be
orthogonal -- e.g., OFDM). We present analytical results that characterize the
uplink and downlink capacity region and efficient algorithms for computing rate
pairs at the region's boundary. We also provide near-optimal and heuristic
algorithms that "convexify" the capacity region when it is not convex. The
convexified region corresponds to a combination of a few full-duplex rates
(i.e., to time sharing between different operation modes). The algorithms can
be used for theoretical characterization of the capacity region as well as for
resource (time, power, and channel) allocation with the objective of maximizing
the sum of the rates when one of them (uplink or downlink) must be guaranteed
(e.g., due to QoS considerations). We numerically illustrate the capacity
regions and the rate gains (compared to time division duplex) for various
channel and cancellation scenarios. The analytical results provide insights
into the properties of the full-duplex capacity region and are essential for
future development of scheduling, channel allocation, and power control
algorithms.


title:
On Functional and Holographic Renormalization Group Methods in
  Stochastic Theory of Turbulence

abstract:
  A nonlocal quantum-field model is constructed for the system of hydrodynamic
equations for incompressible viscous fluid (the stochastic Navier--Stokes (NS)
equation and the continuity equation). This model is studied by the following
two mutually parallel methods: the Wilson--Polchinski functional
renormalization group method (FRG), which is based on the exact functional
equation for the generating functional of amputated connected Green's functions
(ACGF), and the Heemskerk--Polchinski holographic renormalization group method
(HRG), which is based on the functional Hamilton--Jacobi (HJ) equation for the
holographic boundary action. Both functional equations are equivalent to
infinite hierarchies of integro-differential equations (coupled in the FRG
case) for the corresponding families of Green's functions (GF). The RG-flow
equations can be derived explicitly for two-particle functions. Because the
HRG-flow equation is closed (contains only a two-particle GF), the explicit
analytic solutions are obtained for the two-particle GF (in terms of the
modified Bessel functions $I$ and $K$) in the framework of the minimal
holographic model and its simple generalization, and these solutions have a
remarkable property of minimal dependence on the details of the random force
correlator (the function of the energy pumping into the system). The
restrictions due to the time-gauged Galilean symmetry present in this theory,
the problem of choosing the pumping function, and some generalizations of the
standard RG-flow procedures are discussed in detail. Finally, the question of
whether the HRG-solutions can be used to solve the FRG-flow equation for the
two-particle GF (in particular, the relationship between the regulators in the
two methods) is studied.


title: On Discrete Gauge Symmetries in Trinification Model

abstract:
  Given the important role of discrete gauge symmetries in viable models, we
discuss these symmetries in intersecting D6-brane trinification model where the
ZN symmetry is investigated and its identification is shown.


title:
Aqueous ammonium thiocyanate solutions as refractive index-matching
  fluids with low density and viscosity

abstract:
  We show that aqueous solutions of ammonium thiocyanate (NH4SCN) can be used
to match the index of refraction of several transparent materials commonly used
in experiments, while maintaining low viscosity and density compared to other
common refractive index-matching liquids. We present empirical models for
estimating the index of refraction, density, and kinematic viscosity of these
solutions as a function of temperature and concentration. Finally, we summarize
the chemical compatibility of ammonium thiocyanate with materials commonly used
in apparatus.


title:
Realization of phase modulation using a spatial light modulator in the
  quantum Talbot configuration

abstract:
  We demonstrate the quantum Talbot effect using pairs of single photons
produced by parametric down conversion. In contrast to the previous works, we
use a programmable spatial light modulator to behave as a diffraction grating.
Thus, the investigation of the Talbot diffraction patterns under the variation
of grating structure can be easily performed. The influence of spectral
bandwidth of the down-converted photons on the diffraction pattern is also
investigated. A theoretical model based on the wave nature of photons is
presented to explain the Talbot diffraction pattern under varying conditions.
The measured diffraction patterns are in good agreement with the theoretical
prediction. We are convinced that our study improves the understanding of the
quantum Talbot effect.


title:
Search for high-Tc conventional superconductivity at megabar pressures
  in the lithium-sulfur system

abstract:
  Motivated by the recent report of superconductivity above 200 K in
ultra-dense hydrogen sulfide, we search for high-\tc\ conventional
superconductivity in the phase diagram of the binary Li-S system, using {\em
ab-initio} methods for crystal structure prediction and linear response
calculations for the electron-phonon coupling. We find that at pressures higher
than 20 GPa, several new compositions, besides the known Li$_2$S, are
stabilized; many exhibit electride-like {\em interstitial} charge localization
observed in other alkali metal compounds. Of all predicted phases, only Li$_3$S
at P > 640 GPa displays a sizable \tc, in contrast to what is observed in
sulfur and phosphorus hydrides, where several stoichiometries lead to high \tc.
We attribute this difference to 2$s$-2$p$ hybridization and avoided core
overlap, and predict similar behavior for other alkali metal compounds.


title:
Mid-infrared dust in two nearby radio galaxies, NGC 1316 (Fornax A) and
  NGC 612 (PKS 0131-36)

abstract:
  Most radio galaxies are hosted by giant gas-poor ellipticals, but some
contain significant amounts of dust, which is likely to be of external origin.
In order to characterize the mid-IR properties of two of the most nearby and
brightest merger-remnant radio galaxies of the Southern hemisphere, NGC 1316
(Fornax A) and NGC 612 (PKS 0131-36), we used observations with the Wide-field
Infrared Survey Explorer (WISE) at wavelengths of 3.4, 4.6, 12 and 22 micron
and Spitzer mid-infrared spectra. By applying a resolution-enhancement
technique, new WISE images were produced at angular resolutions ranging from
2.6" to 5.5". Global measurements were performed in the four WISE bands, and
stellar masses and star-formation rates were estimated using published scaling
relations. Two methods were used to uncover the distribution of dust, one
relying on two-dimensional fits to the 3.4 micron images to model the
starlight, and the other one using a simple scaling and subtraction of the 3.4
micron images to estimate the stellar continuum contribution to the emission in
the 12 and 22 micron bands. The two galaxies differ markedly in their mid-IR
properties. The 3.4 micron brightness distribution can be well represented by
the superposition of two Sersic models in NGC 1316 and by a Sersic model and an
exponential disk in NGC 612. The WISE colors of NGC 1316 are typical of those
of early-type galaxies; those of NGC 612 are in the range found for
star-forming galaxies. From the 22 micron luminosity, we infer a star-formation
rate of about 0.7 solar masses per year in NGC 1316 and about 7 solar masses
per year in NGC 612. Spitzer spectroscopy shows that the 7.7-to-11.3 micron PAH
line ratio is significantly lower in NGC 1316 than in NGC 612. The WISE images
reveal resolved emission from dust in the central 1'-2' of the galaxies.
(Abridged)


title:
Multiscale method for Oseen problem in porous media with non-periodic
  grain patterns

abstract:
  Accurate prediction of the macroscopic flow parameters needed to describe
flow in porous media relies on a good knowledge of flow field distribution at a
much smaller scale---in the pore spaces. The extent of the inertial effect in
the pore spaces can not be underestimated yet is often ignored in large-scale
simulations of fluid flow. We present a multiscale method for solving Oseen's
approximation of incompressible flow in the pore spaces amid non-periodic grain
patterns. The method is based on the multiscale finite element method (MsFEM
[Hou and Wu, 1997]) and is built in the vein of Crouzeix-Raviart elements
[Crouzeix and Raviart, 1973]. Simulations of inertial flow in highly
non-periodic settings are conducted and presented. Convergence studies in terms
of numerical errors relative to the reference solution are given to demonstrate
the accuracy of our method. The weakly enforced continuity across coarse
element edges is shown to maintain accurate solutions in the vicinity of the
grains without the need for any oversampling methods. The penalization method
is employed to allow a complicated grain pattern to be modeled using a simple
Cartesian mesh. This work is a stepping stone towards solving the more
complicated Navier-Stokes equations with a non-linear inertial term.


title: Large BR(h -> tau mu) in Supersymmetric Models

abstract:
  We analyze the Lepton Flavor Violating (LFV) Higgs decay h -> tau mu in three
supersymmetric models: Minimal Supersymmetric Standard Model (MSSM),
Supersymmetric Seesaw Model (SSM), and Supersymmetric B-L model with Inverse
Seesaw (BLSSM-IS). We show that in generic MSSM, with non-universal slepton
masses and/or trilinear couplings, it is not possible to enhance BR(h -> tau
mu) without violating the experimental bound on the BR(tau -> mu gamma). In
SSM, where flavor mixing is radiatively generated, the LFV process mu -> e
gamma strictly constrains the parameter space and the maximum value of BR(h ->
tau mu) is of order 10^-10, which is extremely smaller than the recent results
reported by the CMS and ATLAS experiments. In BLSSM-IS, with universal soft
SUSY breaking terms at the grand unified scale, we emphasize that the measured
values of BR(h -> tau mu) can be accommodated in a wide region of parameter
space without violating LFV constraints. Thus, confirming the LFV Higgs decay
results will be a clear signal of BLSSM-IS type of models. Finally, the signal
of h -> tau mu in the BLSSM-IS at the LHC, which has a tiny background, is
analyzed.


title:
Viable route towards large-area two dimensional MoS2 using magnetron
  sputtering

abstract:
  Structural, interfacial, optical, and transport properties of large-area MoS2
ultra-thin films on BN-buffered silicon substrates fabricated using magnetron
sputtering are investigated. A relatively simple growth strategy is
demonstrated here that simultaneously promotes superior interfacial and bulk
MoS2 properties. Few layers of MoS2 are established using X-ray reflectivity,
diffraction, ellipsometry, and Raman spectroscopy measurements. Layer-specific
modeling of optical constants shows very good agreement with first-principles
calculations. Conductivity measurements reveal that few-layer MoS2 films are
more conducting than many-layer films. Photo-conductivity measurements reveal
that the sputter deposited MoS2 films compare favorably with other large-area
methods. Our work illustrates that sputtering is a viable route for large-area
device applications using transition metal dichalcogenides.


title:
D-meson production in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV
  and in pp collisions at $\sqrt{s}=7$ TeV

abstract:
  The production cross sections of the prompt charmed mesons D$^0$, D$^+$,
D$^{*+}$ and D$_s$ were measured at mid-rapidity in p-Pb collisions at a
centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}}=5.02$ TeV with the
ALICE detector at the LHC. D mesons were reconstructed from their decays
D$^0\rightarrow{\rm K}^-\pi^+$, D$^+\rightarrow{\rm K}^-\pi^+\pi^+$,
D$^{*+}\rightarrow D^0\pi^+$, D$_s^+\rightarrow\phi\pi^+\rightarrow{\rm
K}^-{\rm K}^+\pi^+$, and their charge conjugates. The $p_{\rm T}$-differential
production cross sections were measured at mid-rapidity in the interval
$1<p_{\rm T}<24$ GeV/$c$ for D$^0$, D$^+$ and D$^{*+}$ mesons and in $2<p_{\rm
T}<12$ GeV/$c$ for D$_s$ mesons, using an analysis method based on the
selection of decay topologies displaced from the interaction vertex. The
production cross sections of the D$^0$, D$^+$ and D$^{*+}$ mesons were also
measured in three $p_{\rm T}$ intervals as a function of the rapidity $y_{\rm
cms}$ in the centre-of-mass system in $-1.26<y_{\rm cms}<0.34$. In addition,
the prompt D$^0$ cross section was measured in pp collisions at $\sqrt{s}=7$
TeV and p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV down to $p_{\rm T}=0$
using an analysis technique that is based on the estimation and subtraction of
the combinatorial background, without reconstruction of the D$^0$ decay vertex.
The nuclear modification factor $R_{\rm pPb}(p_{\rm T})$, defined as the ratio
of the $p_{\rm T}$-differential D-meson cross section in p-Pb collisions and
that in pp collisions scaled by the mass number of the Pb nucleus, was
calculated for the four D-meson species and found to be compatible with unity
within experimental uncertainties. The results are compared to theoretical
calculations that include cold-nuclear-matter effects and to transport model
calculations incorporating the interactions of charm quarks with an expanding
deconfined medium.


title: Random matrices: Law of the iterated logarithm

abstract:
  The theory of random matrices contains many central limit theorems. We have
central limit theorems for eigenvalues statistics, for the log-determinant and
log-permanent, for limiting distribution of individual eigenvalues in the bulk,
and many others.
  In this notes, we discuss the following problem: Is it possible to prove the
law of the iterated logarithm? We illustrate this possibility by showing that
this is indeed the case for the log of the permanent of random Bernoulli
matrices and pose open questions concerning several other matrix parameters.


title: Sequential Neural Models with Stochastic Layers

abstract:
  How can we efficiently propagate uncertainty in a latent state representation
with recurrent neural networks? This paper introduces stochastic recurrent
neural networks which glue a deterministic recurrent neural network and a state
space model together to form a stochastic and sequential neural generative
model. The clear separation of deterministic and stochastic layers allows a
structured variational inference network to track the factorization of the
model's posterior distribution. By retaining both the nonlinear recursive
structure of a recurrent neural network and averaging over the uncertainty in a
latent path, like a state space model, we improve the state of the art results
on the Blizzard and TIMIT speech modeling data sets by a large margin, while
achieving comparable performances to competing methods on polyphonic music
modeling.


title: On the Formation of Equilibrium Gels via a Macroscopic Bond Limitation

abstract:
  Restricting the number of attractive physical "bonds" that can form between
particles in a fluid suppresses the usual demixing phase transition to very low
particle concentrations, allowing for the formation of open, percolated, and
homogeneous states, aptly called equilibrium or "empty" gels. Most
demonstrations of this concept have directly limited the microscopic particle
valence via anisotropic (patchy) attractions; however, an alternative
macroscopic valence limitation would be desirable for greater experimental
tunability and responsiveness. One possibility, explored in this paper, is to
employ primary particles with attractions mediated via a secondary species of
linking particles. In such a system, the linker-to-primary particle ratio
serves as a macroscopic control parameter for the average microscopic valence.
We show that the phase behavior of such a system predicted by Wertheim's first
order perturbation theory is consistent with equilibrium gel formation: the
primary particle concentrations corresponding to the two-phase demixing
transition are significantly suppressed at both low and high linker-to-primary
particle ratios. Extensive molecular dynamics simulations validate these
theoretical predictions but also reveal the presence of loops of bonded
particles, which are neglected in the theory. Such loops cause densification
and inhibit percolation, and hence the range of viable empty gel state
conditions is somewhat reduced relative to the Wertheim theory predictions.


title:
A local characterization for constant curvature metrics in 2-dimensional
  Lorentz manifolds

abstract:
  In this paper we define Fermi-type coordinates in a 2-dimensional Lorentz
manifold, and use this coordinate system to provide a local characterization of
constant Gaussian curvature metrics for such manifolds, following a classical
result from Riemann. We then exhibit particular isometric immersions of such
metrics in the pseudo-Riemannian ambients L^3 (i.e., usual Lorentz-Minkowski
space) and R^3_2 (i.e., R^3 endowed with an index 2 flat metric).


title:
Towards Bin Packing (preliminary problem survey, models with multiset
  estimates)

abstract:
  The paper described a generalized integrated glance to bin packing problems
including a brief literature survey and some new problem formulations for the
cases of multiset estimates of items. A new systemic viewpoint to bin packing
problems is suggested: (a) basic element sets (item set, bin set, item subset
assigned to bin), (b) binary relation over the sets: relation over item set as
compatibility, precedence, dominance; relation over items and bins (i.e.,
correspondence of items to bins). A special attention is targeted to the
following versions of bin packing problems: (a) problem with multiset estimates
of items, (b) problem with colored items (and some close problems). Applied
examples of bin packing problems are considered: (i) planning in paper industry
(framework of combinatorial problems), (ii) selection of information messages,
(iii) packing of messages/information packages in WiMAX communication system
(brief description).


title: How can a clairvoyant particle escape the exclusion process?

abstract:
  We study a detection problem in the following setting: On the one-dimensional
integer lattice, at time zero, place nodes on each site independently with
probability $\rho \in [0,1)$ and let them evolve as a simple symmetric
exclusion process. At time zero, place a target at the origin. The target moves
only at integer times, and can move to any site that is within distance $R$
from its current position. Assume also that the target can predict the future
movement of all nodes. We prove that, for $R$ large enough (depending on the
value of $\rho$) it is possible for the target to avoid detection forever with
positive probability. The proof of this result uses two ingredients of
independent interest. First we establish a renormalisation scheme that can be
used to prove percolation for dependent oriented models under a certain
decoupling condition. This result is general and does not rely on the
specifities of the model. As an application, we prove our main theorem for
different dynamics, such as independent random walks and independent renewal
chains. We also proof existence of oriented percolation for random
interlacements and for its vacant set for large dimensions . The second step of
the proof is a space-time decoupling for the exclusion process.


title:
Static and dynamical quantum correlations in phases of an alternating
  field XY model

abstract:
  We investigate the static and dynamical patterns of entanglement in an
anisotropic XY model with an alternating transverse magnetic field, which is
equivalent to a two-component one-dimensional Fermi gas on a lattice, a system
realizable with current technology. Apart from the antiferromagnetic and
paramagnetic phases, the model possesses a dimer phase which is not present in
the transverse XY model. At zero temperature, we find that the first derivative
of bipartite entanglement can detect all the three phases. We analytically show
that the model has a "factorization line" on the plane of system parameters, in
which the zero temperature state is separable. Along with investigating the
effect of temperature on entanglement in a phase plane, we also report a
non-monotonic behavior of entanglement with respect to temperature in the
anti-ferromagnetic and paramagnetic phases, which is surprisingly absent in the
dimer phase. Since the time dynamics of entanglement in a realizable physical
system plays an important role in quantum information processing tasks, the
evolutions of entanglement at small as well as large time are examined.
Consideration of large time behavior of entanglement helps us to prove that in
this model, entanglement is always ergodic. We observe that other quantum
correlation measures can qualitatively show similar features in zero and finite
temperatures. However, unlike nearest-neighbor entanglement, the
nearest-neighbor information theoretic measures can be both ergodic as well as
non-ergodic, depending on the system parameters.


title: AUTO2, a saturation-based heuristic prover for higher-order logic

abstract:
  We introduce a new theorem prover for classical higher-order logic named
auto2. The prover is designed to make use of human-specified heuristics when
searching for proofs. The core algorithm is a best-first search through the
space of propositions derivable from the initial assumptions, where new
propositions are added by user-defined functions called proof steps. We
implemented the prover in Isabelle/HOL, and applied it to several formalization
projects in mathematics and computer science, demonstrating the high level of
automation it can provide in a variety of possible proof tasks.


title: Large-scale Charging of Electric Vehicles: A Multi-Armed Bandit Approach

abstract:
  The successful launch of electric vehicles (EVs) depends critically on the
availability of convenient and economic charging facilities. The problem of
scheduling of large-scale charging of EVs by a service provider is considered.
A Markov decision process model is introduced in which EVs arrive randomly at a
charging facility with random demand and completion deadlines. The service
provider faces random charging costs, convex non-completion penalties, and a
peak power constraint that limits the maximum number of simultaneous activation
of EV chargers.
  Formulated as a restless multi-armed bandit problem, the EV charging problem
is shown to be indexable. A closed-form expression of the Whittle's index is
obtained for the case when the charging costs are constant. The Whittle's index
policy, however, is not optimal in general. An enhancement of the Whittle's
index policy based on spatial interchange according to the less laxity and
longer processing time principle is presented. The proposed policy outperforms
existing charging algorithms, especially when the charging costs are time
varying.


title: Martian zeolites as a source of atmospheric methane

abstract:
  The origin of the martian methane is still poorly understood. A plausible
explanation is that methane could have been produced either by hydrothermal
alteration of basaltic crust or by serpentinization of ultramafic rocks
producing hydrogen and reducing crustal carbon into methane. Once formed,
methane storage on Mars is commonly associated with the presence of hidden
clathrate reservoirs. Here, we alternatively suggest that chabazite and
clinoptilolite, which belong to the family of zeolites, may form a plausible
storage reservoir of methane in the martian subsurface. Because of the
existence of many volcanic terrains, zeolites are expected to be widespread on
Mars and their Global Equivalent Layer may range up to more than $\sim$1 km,
according to the most optimistic estimates. If the martian methane present in
chabazite and clinoptilolite is directly sourced from an abiotic source in the
subsurface, the destabilization of a localized layer of a few millimeters per
year may be sufficient to explain the current observations. The sporadic
release of methane from these zeolites requires that they also remained
isolated from the atmosphere during its evolution. The methane release over the
ages could be due to several mechanisms such as impacts, seismic activity or
erosion. If the methane outgassing from excavated chabazite and/or
clinoptilolite prevails on Mars, then the presence of these zeolites around
Gale Crater could explain the variation of methane level observed by Mars
Science Laboratory.


title: Weight representations of admissible affine vertex algebras

abstract:
  For an admissible affine vertex algebra $V_k(\mathfrak{g})$ of type $A$, we
describe a new family of relaxed highest weight representations of
$V_k(\mathfrak{g})$. They are simple quotients of representations of the affine
Kac-Moody algebra $\widehat{\mathfrak{g}}$ induced from the following
$\mathfrak{g}$-modules: 1) generic Gelfand-Tsetlin modules in the principal
nilpotent orbit, in particular all such modules induced from $\mathfrak{sl}_2$;
2) all Gelfand-Tsetlin modules in the principal nilpotent orbit which are
induced from $\mathfrak{sl}_3$; 3) all simple Gelfand-Tsetlin modules over
$\mathfrak{sl}_3$. This in particular gives the classification of all simple
positive energy weight representations of $V_k(\mathfrak{g})$ with finite
dimensional weight spaces for $\mathfrak{g}=\mathfrak{sl}_3$.


title: Generalized characteristics and Lax-Oleinik operators: global theory

abstract:
  For autonomous Tonelli systems on $\R^n$, we develop an intrinsic proof of
the existence of generalized characteristics using sup-convolutions. This
approach, together with convexity estimates for the fundamental solution, leads
to new results such as the global propagation of singularities along
generalized characteristics.


title: Pressure-Induced Confined Metal from the Mott Insulator Sr3Ir2O7

abstract:
  The spin-orbit Mott insulator Sr3Ir2O7 provides a fascinating playground to
explore insulator-metal transition driven by intertwined charge, spin, and
lattice degrees of freedom. Here, we report high pressure electric resistance
and resonant inelastic x ray scattering measurements on single crystal Sr3Ir2O7
up to 63 65 GPa at 300 K. The material becomes a confined metal at 59.5 GPa,
showing metallicity in the ab plane but an insulating behavior along the c
axis. Such an unusual phenomenon resembles the strange metal phase in cuprate
superconductors. Since there is no sign of the collapse of spin orbit or
Coulomb interactions in x-ray measurements, this novel insulator metal
transition is potentially driven by a first-order structural change at nearby
pressures. Our discovery points to a new approach for synthesizing functional
materials.


title: Recursive Sampling for the Nystr\"om Method

abstract:
  We give the first algorithm for kernel Nystr\"om approximation that runs in
*linear time in the number of training points* and is provably accurate for all
kernel matrices, without dependence on regularity or incoherence conditions.
The algorithm projects the kernel onto a set of $s$ landmark points sampled by
their *ridge leverage scores*, requiring just $O(ns)$ kernel evaluations and
$O(ns^2)$ additional runtime. While leverage score sampling has long been known
to give strong theoretical guarantees for Nystr\"om approximation, by employing
a fast recursive sampling scheme, our algorithm is the first to make the
approach scalable. Empirically we show that it finds more accurate, lower rank
kernel approximations in less time than popular techniques such as uniformly
sampled Nystr\"om approximation and the random Fourier features method.


title: Light Adjoint Quarks in the Instanton-Dyon Liquid Model IV

abstract:
  We discuss the instanton-dyon liquid model with $N_f$ Majorana quark flavors
in the adjoint representation of color $SU_c(2)$ at finite temperature. We
briefly recall the index theorem on $S^1\times R^3$ for twisted adjoint
fermions in a BPS dyon background of arbitrary holonomy, and use the ADHM
construction to explicit the adjoint anti-periodic zero modes. We use these
results to derive the partition function of an interacting instanton-dyon
ensemble with $N_f$ light and anti-periodic adjoint quarks. We develop the
model in details by mapping the theory on a 3-dimensional quantum effective
theory with adjoint quarks with manifest $SU(N_f)\times Z_{4N_f}$ symmetry.
Using a mean-field analysis at weak coupling and strong screening, we show that
center symmetry requires the spontaneous breaking of chiral symmetry, which is
shown to only take place for $N_f=1$. For a sufficiently dense liquid, we find
that the ground state is center symmetric and breaks spontaneously flavor
symmetry through $SU(N_f)\times Z_{4N_f}\rightarrow O(N_f)$. As the liquid
dilutes with increasing temperature, center symmetry and chiral symmetry are
restored. We present numerical and analytical estimates for the transition
temperatures.


title: Ultradilute low-dimensional liquids

abstract:
  We calculate the energy of one- and two-dimensional weakly interacting
Bose-Bose mixtures analytically in the Bogoliubov approximation and by using
the diffusion Monte Carlo technique. We show that in the case of attractive
inter- and repulsive intraspecies interactions the energy per particle has a
minimum at a finite density corresponding to a liquid state. We derive the
Gross-Pitaevskii equation to describe droplets of such liquids and solve it
analytically in the one-dimensional case.


title: Natural Scene Image Segmentation Based on Multi-Layer Feature Extraction

abstract:
  This paper addresses the problem of natural image segmentation by extracting
information from a multi-layer array which is constructed based on color,
gradient, and statistical properties of the local neighborhoods in an image. A
Gaussian Mixture Model (GMM) is used to improve the effectiveness of local
spectral histogram features. Grouping these features leads to forming a rough
initial over-segmented layer which contains coherent regions of pixels. The
regions are merged by using two proposed functions for calculating the distance
between two neighboring regions and making decisions about their merging.
Extensive experiments are performed on the Berkeley Segmentation Dataset to
evaluate the performance of our proposed method and compare the results with
the recent state-of-the-art methods. The experimental results indicate that our
method achieves higher level of accuracy for natural images compared to recent
methods.


title: Levy random walks on multiplex networks

abstract:
  Random walks constitute a fundamental mechanism for many dynamics taking
place on complex networks. Besides, as a more realistic description of our
society, multiplex networks have been receiving a growing interest, as well as
the dynamical processes that occur on top of them. Here, inspired by one
specific model of random walks that seems to be ubiquitous across many
scientific fields, the Levy flight, we study a new navigation strategy on top
of multiplex networks. Capitalizing on spectral graph and stochastic matrix
theories, we derive analytical expressions for the mean first passage time and
the average time to reach a node on these networks. Moreover, we also explore
the efficiency of Levy random walks, which we found to be very different as
compared to the single layer scenario, accounting for the structure and
dynamics inherent to the multiplex network. Finally, by comparing with some
other important random walk processes defined on multiplex networks, we find
that in some region of the parameters, a Levy random walk is the most efficient
strategy. Our results give us a deeper understanding of Levy random walks and
show the importance of considering the topological structure of multiplex
networks when trying to find efficient navigation strategies.


title: A Consistent Regularization Approach for Structured Prediction

abstract:
  We propose and analyze a regularization approach for structured prediction
problems. We characterize a large class of loss functions that allows to
naturally embed structured outputs in a linear space. We exploit this fact to
design learning algorithms using a surrogate loss approach and regularization
techniques. We prove universal consistency and finite sample bounds
characterizing the generalization properties of the proposed methods.
Experimental results are provided to demonstrate the practical usefulness of
the proposed approach.


title: Fluid moments of the Landau collision operator

abstract:
  One important problem in plasma physics is the lack of an accurate and
complete description of Coulomb collisions in associated fluid models. To shed
light on the problem, this Letter introduces an integral identity involving the
multi-dimensional Hermite tensor polynomials and presents a method for
computing exact expressions for the fluid moments of the nonlinear Landau
collision operator. The proposed methodology provides a systematic and rigorous
means of extending the validity of fluid models that have an underlying
inverse-square force particle dynamics to weakly collisional and strong flow
regimes.

categories: physics.plasm-ph math-ph math.MP physics.flu-dyn


title: Non-elementary Fano conic bundles

abstract:
  We study a particular kind of fiber type contractions between complex,
projective, smooth varieties f:X->Y, called Fano conic bundles. This means that
X is a Fano variety, and every fiber of f is isomorphic to a plane conic.
Denoting by rho_{X} the Picard number of X, we investigate such contractions
when rho_{X}-rho_{Y} is greater than 1, called non-elementary. We prove that
rho_{X}-rho_{Y} is at most 8, and we deduce new geometric information about our
varieties, depending on rho_{X}-rho_{Y}. Moreover, when X is locally factorial
with canonical singularities and with at most finitely many non-terminal
points, we consider fiber type K_{X}-negative contractions f:X->Y with
one-dimensional fibers, and we show that rho_{X}-rho_{Y} is at most 9.


title:
From the free boundary condition for Hele-Shaw to a fractional parabolic
  equation

abstract:
  We propose a method to determine the smoothness of sufficiently flat
solutions of one phase Hele-Shaw problems. The novelty is the observation that
under a flatness assumption the free boundary --represented by the hodograph
transform of the solution- solves a nonlinear integro-differential equation.
This nonlinear equation is linearized to a (nonlocal) parabolic equation with
bounded measurable coefficients, for which regularity estimates are available.
This fact is used to prove a regularity result for the free boundary of a weak
solution near points where the solution looks sufficiently flat. More
concretely, flat means that in a parabolic neighborhood of the point the
solution lies between the solutions corresponding to two parallel flat fronts a
small distance apart --a condition that only depends on the the local behavior
of the solution. In a neighborhood of such a point, the free boundary is given
by the graph of a function whose spatial gradient enjoys a universal H\"older
estimate in both space and time.


title: Dispersionless (3+1)-dimensional integrable hierarchies

abstract:
  In the present paper we introduce a multi-dimensional version of the R-matrix
approach to the construction of integrable hierarchies. Applying this method to
the case of the Lie algebra of functions with respect to the contact bracket,
we construct integrable hierarchies of (3+1)-dimensional dispersionless systems
of the type recently introduced by one of us in arXiv:1401.2122.


title:
Groups with minimal harmonic functions as small as you like (With an
  appendix by Nicolas Matte Bon)

abstract:
  For any order of growth $f(n)=o(\log n)$ we construct a finitely-generated
group $G$ and a set of generators $S$ such that the Cayley graph of $G$ with
respect to $S$ supports a harmonic function with growth $f$ but does not
support any harmonic function with slower growth. The construction uses
permutational wreath products in which the base group is defined via its
properly chosen Schreier graph.


title: p-cyclic persistent homology and Hofer distance

abstract:
  In this paper, we generalize the result from L. Polterovich and E.
Shelukhin's paper stating that Hofer distance from time-dependent Hamiltonian
diffeomorphism to the set of p-th power Hamiltonian diffeomorphism can be
arbitrarily large to hold in the product structure $\Sigma_g \times M$ for any
closed symplectic manifold $M$ when $p$ is sufficiently large and $g \geq 4$.
This implies that, on this product, Hofer distance can be arbitrarily large
between time-dependent Hamiltonian diffeomorphism and autonomous Hamiltonian
diffeomorphism.The basic tool we use is barcode and singular value
decomposition that are developed in previous joint work with M. Usher, from
which we borrow many proofs and modify them so that it can be adapted to the
situation that filtered chain complex equipped with a group action.


title:
The merger history of the complex cluster Abell 1758: a combined weak
  lensing and spectroscopic view

abstract:
  We present a weak-lensing and dynamical study of the complex cluster Abell
1758 (A1758, z = 0.278) supported by hydrodynamical simulations. This cluster
is composed of two main structures, called A1758N and A1758S. The Northern
structure is composed of A1758NW & A1758NE, with lensing determined masses of
7.90_{-1.55}^{+1.89} X 10^{14} M_\odot and 5.49_{-1.33}^{+1.67} X 10^{14}
M_\odot, respectively. They show a remarkable feature: while in A1758NW there
is a spatial agreement among weak lensing mass distribution, intracluster
medium and its brightest cluster galaxy (BCG) in A1758NE the X-ray peak is
located 96_{-15}^{+14} arcsec away from the mass peak and BCG positions. Given
the detachment between gas and mass we could use the local surface mass density
to estimate an upper limit for the dark matter self-interaction cross section:
\sigma/m<5.83 cm^2 g^{-1}. Combining our velocity data with hydrodynamical
simulations we have shown that A1758 NW \& NE had their closest approach 0.27
Gyr ago and their merger axis is 21+-12 degrees from the plane of the sky. In
the A1758S system we have measured a total mass of 4.96_{-1.19}^{+1.08} X
10^{14} M_\odot and, using radial velocity data, we found that the main merger
axis is located at 70+-4 degrees from the plane of the sky, therefore closest
to the line-of-sight.


title: Local Minimax Complexity of Stochastic Convex Optimization

abstract:
  We extend the traditional worst-case, minimax analysis of stochastic convex
optimization by introducing a localized form of minimax complexity for
individual functions. Our main result gives function-specific lower and upper
bounds on the number of stochastic subgradient evaluations needed to optimize
either the function or its "hardest local alternative" to a given numerical
precision. The bounds are expressed in terms of a localized and computational
analogue of the modulus of continuity that is central to statistical minimax
analysis. We show how the computational modulus of continuity can be explicitly
calculated in concrete cases, and relates to the curvature of the function at
the optimum. We also prove a superefficiency result that demonstrates it is a
meaningful benchmark, acting as a computational analogue of the Fisher
information in statistical estimation. The nature and practical implications of
the results are demonstrated in simulations.


title:
Study on the fabrication of low-pass metal powder filters for use at
  cryogenic temperatures

abstract:
  We fabricated compact low-pass stainless-steel powder filters for use in
low-noise measurements at cryogenic temperatures and investigated their
attenuation characteristics for different wire lengths, shapes, and preparation
methods up to 20 GHz. We used nominally 30-micrometer-sized SUS 304L powder and
mixed with Stycast 2850FT by Emerson and Cumming with catalyst 23LV. A 0.1 mm
insulated copper wire was wound on preformed powder-mixture spools in the shape
of a right-circular cylinder, a flattened elliptic cylinder and a toroid, and
the coils were encapsulated in metal tubes or boxes filled with the powder
mixture. All the fabricated powder filters showed a large attenuation at high
frequencies with a cut-off frequency near 1 GHz. However, the toroidal filter
showed prominent ripples corresponding to resonance modes in the 0.5-m-long
coil wire. A filter with a 2:1 powder/epoxy mixture mass rate and a wire length
of 1.53 m showed an attenuation of -93 dB at 4 GHz and the attenuation was
linearly proportional to the wire length. As the powder-to-epoxy ratio
increased, the high-frequency attenuation increased. An equally-spaced
single-layer coil structure was found to be more efficient in attenuation than
a double-layer coil. Geometry of the metal filter-case affected noise ripples
with the least noise in a circular-tube case.


title: Ellipses Percolation

abstract:
  We define a continuum percolation model that provides a collection of random
ellipses on the plane and study the behavior of the covered set and the vacant
set, the one obtained by removing all ellipses. Our model generalizes a
construction that appears implicitly in the Poisson cylinder model of Tykesson
and Windisch. The ellipses model has a parameter $\alpha > 0$ associated with
the tail decay of the major axis distribution; we only consider distributions
$\rho$ satisfying $\rho[r, \infty) \asymp r^{-\alpha}$. We prove that this
model presents a double phase transition in $\alpha$. For $\alpha \in (0,1]$
the plane is completely covered by the ellipses, almost surely. For $\alpha \in
(1,2)$ the vacant set is not empty but does not percolate for any positive
density of ellipses, while the covered set always percolates. For $\alpha \in
(2, \infty)$ the vacant set percolates for small densities of ellipses and the
covered set percolates for large densities. Moreover, we prove for the critical
parameter $\alpha = 2$ that there is a non-degenerate interval of density for
which the probability of crossing boxes of a fixed proportion is bounded away
from zero and one, a rather unusual phenomenon. In this interval neither the
covered set nor the vacant set percolate, a behavior that is similar to
critical independent percolation on $\mathbb{Z}^2$.


title: A CMOS silicon spin qubit

abstract:
  Silicon, the main constituent of microprocessor chips, is emerging as a
promising material for the realization of future quantum processors. Leveraging
its well-established complementary metal-oxide-semiconductor (CMOS) technology
would be a clear asset to the development of scalable quantum computing
architectures and to their co-integration with classical control hardware. Here
we report a silicon quantum bit (qubit) device made with an industry-standard
fabrication process. The device consists of a two-gate, p-type transistor with
an undoped channel. At low temperature, the first gate defines a quantum dot
(QD) encoding a hole spin qubit, the second one a QD used for the qubit
readout. All electrical, two-axis control of the spin qubit is achieved by
applying a phase-tunable microwave modulation to the first gate. Our result
opens a viable path to qubit up-scaling through a readily exploitable CMOS
platform.


title:
Decay coupling constants sum rules for dibaryon octet into two baryon
  octets with $\lambda_8$ first order SU(3) symmetry breaking

abstract:
  The SU(3) octet states with baryon number B = 2, hexaquark dibaryons, are
considered. Decay coupling constants sum rules for dibaryon octet into two
ordinary baryon octets with ?$\lambda_8$ first order SU(3) symmetry breaking
are given. An SU(4) extension of the analysis is commented upon. Possibilities
for the experimental observation of multibaryon and anti-multibaryon states are
pointed out.


title: Subordination of trees and the Brownian map

abstract:
  We discuss subordination of random compact R-trees. We focus on the case of
the Brownian tree, where the subordination function is given by the past
maximum process of Brownian motion indexed by the tree. In that particular
case, the subordinate tree is identified as a stable Levy tree with index 3/2.
As a more precise alternative formulation, we show that the maximum process of
the Brownian snake is a time change of the height process coding the Levy tree.
We then apply our results to properties of the Brownian map. In particular, we
recover, in a more precise form, a recent result of Miller and Sheffield
identifying the metric net associated with the Brownian map.


title: Symmetry-broken local-density approximation for one-dimensional systems

abstract:
  Within density-functional theory, the local-density approximation (LDA)
correlation functional is typically built by fitting the difference between the
near-exact and Hartree-Fock (HF) energies of the uniform electron gas (UEG),
together with analytic perturbative results from the high- and low-density
regimes. Near-exact energies are obtained by performing accurate diffusion
Monte Carlo calculations, while HF energies are usually assumed to be the Fermi
fluid HF energy. However, it has been known since the seminal work of
Overhauser that one can obtain lower, symmetry-broken (SB) HF energies at any
density. Here, we have computed the SBHF energies of the one-dimensional UEG
and constructed a SB version of the LDA (SBLDA) from the results. We compare
the performance of the LDA and SBLDA functionals when applied to
one-dimensional systems, including atoms and molecules. Generalization to
higher dimensions is also discussed.

categories: physics.chem-ph cond-mat.other cond-mat.str-el math-ph math.MP physics.comp-ph


title:
Reduced Activity And Large Particles From the Disintegrating Planet
  Candidate KIC 12557548b

abstract:
  The intriguing exoplanet candidate KIC 12557548b is believed to have a
comet-like tail of dusty debris trailing a small rocky planet. The tail of
debris scatters up to 1.3% of the stellar light in the Kepler observatory's
bandpass (0.42 um to 0.9 um). Observing the tail's transit depth at multiple
wavelengths can reveal the composition and particle size of the debris,
constraining the makeup and lifetime of the sub-Mercury planet. Early dust
particle size predictions from the scattering of the comet-like tail pointed
towards a dust size of ~0.1 um for silicate compositions. These small particles
would produce a much deeper optical transit depth than near-infrared transit
depth. We measure a transmission spectrum for KIC 12557548b using the SpeX
spectrograph (covering 0.8 um to 2.4 um) simultaneously with the MORIS imager
taking r' (0.63 um) photometry on the Infrared Telescope Facility for eight
nights and one night in H band (1.63 um) using the Wide-Field IR Camera at the
Palomar 200-inch telescope. The infrared spectra are plagued by systematic
errors, but we argue that sufficient precision is obtained when using
differential spectroscopic calibration when combining multiple nights. The
average differential transmission spectrum is flat, supporting findings that
KIC 12557548b's debris is likely composed of larger particles > ~0.5 um for
pyroxene and olivine and > ~0.2 um for iron and corundum. The r' photometric
transit depths are all below the average Kepler value, suggesting that the
observations occurred during a weak period or that the mechanisms producing
optical broadband transit depths are suppressed.


title: Posterior Dispersion Indices

abstract:
  Probabilistic modeling is cyclical: we specify a model, infer its posterior,
and evaluate its performance. Evaluation drives the cycle, as we revise our
model based on how it performs. This requires a metric. Traditionally,
predictive accuracy prevails. Yet, predictive accuracy does not tell the whole
story. We propose to evaluate a model through posterior dispersion. The idea is
to analyze how each datapoint fares in relation to posterior uncertainty around
the hidden structure. We propose a family of posterior dispersion indices (PDI)
that capture this idea. A PDI identifies rich patterns of model mismatch in
three real data examples: voting preferences, supermarket shopping, and
population genetics.


title:
Precision measurements of Linear Scattering Density using Muon
  Tomography

abstract:
  We demonstrate that muon tomography can be used to precisely measure the
properties of various materials. The materials which have been considered have
been extracted from an experimental blast furnace, including carbon (coke) and
iron oxides, for which measurements of the linear scattering density relative
to the mass density have been performed with an absolute precision of 10%. We
report the procedures that are used in order to obtain such precision, and a
discussion is presented to address the expected performance of the technique
when applied to heavier materials. The results we obtain do not depend on the
specific type of material considered and therefore they can be extended to any
application.


title: Limits on Fast Radio Bursts from Four Years of the V-FASTR Experiment

abstract:
  The V-FASTR experiment on the Very Long Baseline Array was designed to detect
dispersed pulses of milliseconds duration, such as fast radio bursts (FRBs). We
use all V-FASTR data through February 2015 to report V-FASTR's upper limits on
the rates of FRBs, and compare these with re-derived rates from Parkes FRB
detection experiments. V-FASTR's operation at lambda=20 cm allows direct
comparison with the 20 cm Parkes rate, and we derive a power-law limit of
\gamma<-0.4 (95% confidence limit) on the index of FRB source counts,
N(>S)\propto S^\gamma. Using the previously measured FRB rate and the
unprecedented amount of survey time spent searching for FRBs at a large range
of wavelengths (0.3 cm > \lambda > 90 cm), we also place frequency-dependent
limits on the spectral distribution of FRBs. The most constraining frequencies
place two-point spectral index limits of \alpha_{20cm}^{4cm} < 5.8 and
\alpha_{90cm}^{20cm} > -7.6, where fluence F \propto f^\alpha if we assume true
the burst rate reported by Champion et al. (2016) of R(F~0.6 Jy ms) = 7 x 10^3
sky^{-1} day^{-1} (for bursts of ~3 ms duration). This upper limit on \alpha
suggests that if FRBs are extragalactic but non-cosmological, that on average
they are not experiencing excessive free-free absorption due to a medium with
high optical depth (assuming temperature ~8,000 K), which excessively invert
their low-frequency spectrum. This in turn implies that the dispersion of FRBs
arises in either or both of the intergalactic medium or the host galaxy, rather
than from the source itself.


title: On randomly generated intersecting hypergraphs II

abstract:
  Let $c$ be a positive constant. Suppose that $r=o(n^{5/12})$ and the members
of $\binom{[n]}{r}$ are chosen sequentially at random to form an intersecting
hypergraph $\mathcal{H}$. We show that whp $\mathcal{H}$ consists of a simple
hypergraph $\mathcal{S}$ of size $\Theta(r/n^{1/3})$, a distinguished vertex
$v$ and all $r$-sets which contain $v$ and meet every edge of $\mathcal{S}$.
This is a continuation of the study of such random intersecting systems started
in [Electron. J. Combin, (2003) R29] where the case $r=O(n^{1/3})$ was
considered. To obtain the stated result we continue to investigate this
question in the range $\omega(n^{1/3})\le r \le o(n^{5/12})$.


title: On randomly generated intersecting hypergraphs

abstract:
  Let $c$ be a positive constant. We show that if $r=\lfloor cn^{1/3}\rfloor$
and the members of ${[n]\choose r}$ are chosen sequentially at random to form
an intersecting hypergraph then with limiting probability $(1+c^3)^{-1}$, as
$n\to\infty$, the resulting family will be of maximum size ${n-1\choose r-1}$.


title: What can we really infer from GW 150914? (II)

abstract:
  In a recent letter we have outlined some issues on GW 150914, we hereby give
additional details. We analyze the event GW 150914 announced by the Advanced
Laser Interferometer Gravitational-Wave Observatory (LIGO) as the
gravitational-wave emission of a black-hole binary merger. We show that the
parameters of the coalescing system and of the newly formed Kerr black-hole can
be extracted from basic results of the gravitational-wave emission during the
inspiraling and merger phases without sophisticate numerical simulations. Our
strikingly accurate estimates are based on textbook formulas describing two
different regimes: 1) the binary inspiraling analysis treated in Landau and
Lifshitz textbook, 2) the plunge of a particle into a black-hole, treated in
the Rees-Ruffini-Wheeler textbook as well as 3) the transition between these
two regimes following Detweiler's treatment of a particle infalling with
non-zero angular momentum onto a black-hole. It is stressed that in order to
infer any astrophysical information on the masses of the system both regimes
have to be independently and observationally constrained by LIGO, which does
not appear to be the case.


title: Quantum Yang--Mills Dark Energy

abstract:
  In this short review, I discuss basic qualitative characteristics of quantum
non-Abelian gauge dynamics in the non-stationary background of the expanding
Universe in the framework of the standard Einstein--Yang--Mills formulation. A
brief outlook of existing studies of cosmological Yang--Mills fields and their
properties will be given. Quantum effects have a profound impact on the gauge
field-driven cosmological evolution. In particular, a dynamical formation of
the spatially-homogeneous and isotropic gauge field condensate may be
responsible for both early and late-time acceleration, as well as for dynamical
compensation of non-perturbative quantum vacua contributions to the ground
state of the Universe. The main properties of such a condensate in the
effective QCD theory at the flat Friedmann--Lema\'itre--Robertson--Walker
(FLRW) background will be discussed within and beyond perturbation theory.
Finally, a phenomenologically consistent dark energy can be induced dynamically
as a remnant of the QCD vacua compensation arising from leading-order
graviton-mediated corrections to the QCD ground state.


title: Generalized Mattig's relation in Brans-Dicke-Rastall gravity

abstract:
  The Geodesic Deviation Equation is being studied in Brans-Dicke-Rastall
gravity. We briefly discuss the Brans-Dicke-Rastall gravity and then construct
GDE for FLRW metric. In this way, the obtained geodesic deviation equation will
correspond to the Brans-Dicke-Rastall gravity. Eventually, we solve numerically
the null vector GDE to obtain from Mattig relation, the deviation vector
$\eta(z)$ and observer area distance $r_0(z)$ and compare the results with
$\Lambda$CDM model.


title: Electrical conductivity of a warm neutron star crust in magnetic fields

abstract:
  We study the electrical conductivity of finite-temperature crust of a warm
compact star which may be formed in the aftermath of a supernova explosion or a
binary neutron star merger as well as when a cold neutron star is heated by
accretion of material from a companion. We focus on the temperature-density
regime where plasma is in the liquid state and, therefore, the conductivity is
dominated by the electron scattering off correlated nuclei. The dynamical
screening of this interaction is implemented in terms of the polarization
tensor computed in the hard-thermal-loop effective field theory of QED plasma.
The correlations of the background ionic component are accounted for via a
structure factor derived from Monte Carlo simulations of one-component plasma.
With this input we solve the Boltzmann kinetic equation in relaxation time
approximation taking into account the anisotropy of transport due to the
magnetic field. The electrical conductivity tensor is studied numerically as a
function of temperature and density for carbon and iron nuclei as well as
density-dependent composition of zero-temperature dense matter in weak
equilibrium with electrons. We also provide accurate fit formulas to our
numerical results as well as supplemental tables which can be used in
dissipative magneto-hydrodynamics simulations of warm compact stars.


title: The square of the 9-hypercube is 14-colorable

abstract:
  The $n$-hypercube, denoted by $Q_n$, has a vertex for each bit string of
length $n$ with two vertices adjacent whenever their Hamming distance is one.
The minimum number of colors needed to color $Q_n$ such that no two vertices at
a distance at most $k$ receive the same color is denoted by
$\chi_{\bar{k}}(n)$. Equivalently, $\chi_{\bar{k}}(n)$ denotes the minimum
number of binary codes with minimum distance at least $k+1$ required to
partition the $n$-dimensional Hamming space. Using a computer search, we
improve upon the known upper bound for $n=9$ by showing that $13 \leq
\chi_{\bar{2}}(9) \leq 14$.


title: Solar System tests in $f(T)$ gravity

abstract:
  We investigate the four solar system tests of gravity - perihelion
precession, light bending, Shapiro time delay, gravitational redshift - in
$f(T)$ gravity. In particular, we investigate the solution derived by Ruggiero
and Radicella, Phys. Rev. D 91, 104014 (2015), for a nondiagonal vierbein field
for a polynomial $f(T) = T + \alpha T^n$, where $\alpha$ is a constant and $|n|
\neq 1$. In this paper, we derive the solutions for each test, in which
Weinberg's, Bodenner and Will's, Cattani et al. and Rindler and Ishak's methods
are applied, Gravitation and Cosmology: Principles and Applications of the
General Theory of Relativity (Wiley, New York, 1972); Am. J. Phys. 71 (2003);
Phys. Rev. D 87, 047503 (2013); Phys. Rev. D 76, 043006 (2007). We set a
constraint on alpha for $n$ = 2, 3 by using data available from literature.


title: Resurgence in complex Chern-Simons theory

abstract:
  We study resurgence properties of partition function of SU(2) Chern-Simons
theory (WRT invariant) on closed three-manifolds. We check explicitly that in
various examples Borel transforms of asymptotic expansions posses expected
analytic properties. In examples that we study we observe that contribution of
irreducible flat connections to the path integral can be recovered from
asymptotic expansions around abelian flat connections. We also discuss
connection to Floer instanton moduli spaces, disk instantons in 2d sigma
models, and length spectra of "complex geodesics" on the A-polynomial curve.

categories: hep-th math-ph math.GT math.MP math.NT math.QA


title: First Detection of a Pulsar Bow Shock Nebula in Far-UV: PSR J0437-4715

abstract:
  Pulsars traveling at supersonic speeds are often accompanied by cometary bow
shocks seen in Halpha. We report on the first detection of a pulsar bow shock
in the far-ultraviolet (FUV). We detected it in FUV images of the nearest
millisecond pulsar J0437-4715 obtained with the Hubble Space Telescope. The
images reveal a bow-like structure positionally coincident with part of the
previously detected Halpha bow shock, with an apex at 10" ahead of the moving
pulsar. Its FUV luminosity, L(1250-2000 A) ~ 5x10^28 erg/s, exceeds the Halpha
luminosity from the same area by a factor of 10. The FUV emission could be
produced by the shocked ISM matter or, less likely, by relativistic pulsar wind
electrons confined by strong magnetic field fluctuations in the bow shock. In
addition, in the FUV images we found a puzzling extended (~3" in size)
structure overlapping with the limb of the bow shock. If related to the bow
shock, it could be produced by an inhomogeneity in the ambient medium or an
instability in the bow shock. We also report on a previously undetected X-ray
emission extending for about 5" ahead of the pulsar, possibly a pulsar wind
nebula created by shocked pulsar wind, with a luminosity L(0.5-8 keV) ~ 3x10^28
erg/s.


title:
On the dynamical state of galaxy clusters: insights from cosmological
  simulations II

abstract:
  Using a suite of cosmology simulations of a sample of $> 120$ galaxy clusters
with $\log(M_{DM, vir}) \le 14.5$. We compare clusters that form in purely dark
matter run and their counterparts in hydro runs and investigate 4 independent
parameters, that are normally used to classify dynamical state. We find that
the virial ratio $\eta$ in hydro-dynamical runs is $\sim 10$ per cent lower
than in the DM run, and there is no clear separation between the relaxed and
unrelaxed clusters for any parameter. Further, using the velocity dispersion
deviation parameter $\zeta$, which is defined as the ratio between cluster
velocity dispersion $\sigma$ and the theoretical prediction $\sigma_t = \sqrt{G
M_{total}/R}$, we find that there is a linear correlation between the virial
ratio $\eta$ and this $\zeta$ parameter. We propose to use this $\zeta$
parameter, which can be easily derived from observed galaxy clusters, as a
substitute of the $\eta$ parameter to quantify the cluster dynamical state.


title: Chemistry and radiative shielding in star forming galactic disks

abstract:
  To understand the conditions under which dense, molecular gas is able to form
within a galaxy, we post-process a series of three-dimensional
galactic-disk-scale simulations with ray-tracing based radiative transfer and
chemical network integration to compute the equilibrium chemical and thermal
state of the gas. In performing these simulations we vary a number of
parameters, such as the ISRF strength, vertical scale height of stellar
sources, cosmic ray flux, to gauge the sensitivity of our results to these
variations. Self-shielding permits significant molecular hydrogen (H2)
abundances in dense filaments around the disk midplane, accounting for
approximately ~10-15% of the total gas mass. Significant CO fractions only form
in the densest, n>~10^3 cm^-3, gas where a combination of dust, H2, and
self-shielding attenuate the FUV background. We additionally compare these
ray-tracing based solutions to photochemistry with complementary models where
photo-shielding is accounted for with locally computed prescriptions. With some
exceptions, these local models for the radiative shielding length perform
reasonably well at reproducing the distribution and amount of molecular gas as
compared with a detailed, global ray tracing calculation. Specifically, an
approach based on the Jeans Length with a T=40K temperature cap performs the
best in regards to a number of different quantitative measures based on the H2
and CO abundances.


title:
Systematic biases in low frequency radio interferometric data due to
  calibration: the LOFAR EoR case

abstract:
  The redshifted 21 cm line of neutral hydrogen is a promising probe of the
Epoch of Reionization (EoR). However, its detection requires a thorough
understanding and control of the systematic errors. We study two systematic
biases observed in the LOFAR EoR residual data after calibration and
subtraction of bright discrete foreground sources. The first effect is a
suppression in the diffuse foregrounds, which could potentially mean a
suppression of the 21 cm signal. The second effect is an excess of noise beyond
the thermal noise. The excess noise shows fluctuations on small frequency
scales, and hence it can not be easily removed by foreground removal or
avoidance methods. Our analysis suggests that sidelobes of residual sources due
to the chromatic point spread function and ionospheric scintillation can not be
the dominant causes of the excess noise. Rather, both the suppression of
diffuse foregrounds and the excess noise can occur due to calibration with an
incomplete sky model containing predominantly bright discrete sources. We show
that calibrating only on bright sources can cause suppression of other signals
and introduce an excess noise in the data. The levels of the suppression and
excess noise depend on the relative flux of sources which are not included in
the model with respect to the flux of modeled sources. We discuss possible
solutions such as using only long baselines to calibrate the interferometric
gain solutions as well as simultaneous multi-frequency calibration along with
their benefits and shortcomings.


title:
II. Apples to apples $A^2$: cluster selection functions for
  next-generation surveys

abstract:
  We present the cluster selection function for three of the largest
next-generation stage-IV surveys in the optical and infrared:
Euclid-Optimistic, Euclid-Pessimistic and the Large Synoptic Survey Telescope
(LSST). To simulate these surveys, we use the realistic mock catalogues
introduced in the first paper of this series.
  We detected galaxy clusters using the Bayesian Cluster Finder (BCF) in the
mock catalogues. We then modeled and calibrated the total cluster stellar mass
observable-theoretical mass ($M^*_{\rm CL}-M_{\rm h}$) relation using a power
law model, including a possible redshift evolution term. We find a moderate
scatter of $\sigma_{M^*_{\rm CL} | M_{\rm h}}$ of 0.124, 0.135 and 0.136 $\rm
dex$ for Euclid-Optimistic, Euclid-Pessimistic and LSST, respectively,
comparable to other work over more limited ranges of redshift. Moreover, the
three datasets are consistent with negligible evolution with redshift, in
agreement with observational and simulation results in the literature.
  We find that Euclid-Optimistic will be able to detect clusters with $>80\%$
completeness and purity down to $8\times10^{13} h^{-1} M_{\odot}$ up to $z<1$.
At higher redshifts, the same completeness and purity are obtained with the
larger mass threshold of $2\times10^{14} h^{-1} M_{\odot}$ up to $z=2$. The
Euclid-Pessimistic selection function has a similar shape with $\sim10\%$
higher mass limit. LSST shows $\sim 5\%$ higher mass limit than
Euclid-Optimistic up to $z<0.7$ and increases afterwards, reaching values of
$2\times10^{14} h^{-1} M_{\odot}$ at $z=1.4$. Similar selection functions with
only $80\%$ completeness threshold have been also computed. The complementarity
of these results with selection functions for surveys in other bands is
discussed.


title:
Lens Models Under the Microscope: Comparison of Hubble Frontier Field
  Cluster Magnification Maps

abstract:
  Using the power of gravitational lensing magnification by massive galaxy
clusters, the Hubble Frontier Fields provide deep views of six patches of the
high redshift Universe. The combination of deep Hubble imaging and exceptional
lensing strength has revealed the greatest numbers of multiply-imaged galaxies
available to constrain models of cluster mass distributions. However, even with
$\mathcal{O}(100)$ images per cluster, the uncertainties associated with the
reconstructions are not negligible. The goal of this paper is to show the
diversity of model magnification predictions. We examine 7 and 9 mass models of
Abell 2744 and MACS J0416, respectively, submitted to the Mikulski Archive for
Space Telescopes for public distribution in September 2015. The dispersion
between model predictions increases from 30% at common low magnifications
($\mu\sim2$) to 70% at rare high magnifications ($\mu\sim40$). MACS J0416
exhibits smaller dispersions than Abell 2744 for $2<\mu<10$. We show that
magnification maps based on different lens inversion techniques typically
differ from each other by more than their quoted statistical errors. This
suggests that some models underestimate the true uncertainties, which are
primarily due to various lensing degeneracies. Though the exact mass sheet
degeneracy is broken, its generalized counterpart is not broken at least in
Abell 2744. Other, local degeneracies are also present in both clusters. Our
comparison of models is complementary to the comparison of reconstructions of
known synthetic mass distributions. By focusing on observed clusters, we can
identify those that are best constrained, and therefore provide the clearest
view of the distant Universe.


title: Kerr-Newman Black Holes with String Corrections

abstract:
  We study $\mathcal{N}=2$ supergravity with higher-derivative corrections that
preserve the $\mathcal{N}=2$ supersymmetry and show that Kerr-Newman black
holes are solutions to these theories. Modifications of the black hole entropy
due to the higher derivatives are universal and apply even in the BPS and
Schwarzschild limits. Our solutions and their entropy are greatly simplified by
supersymmetry of the theory even though the black holes generally do not
preserve any of the supersymmetry.