title:
Unexpected radial trend of the iron abundance in a sample of
  monometallic Galactic globular clusters

abstract:
  We study the relationship between the iron abundance (IA) in red giant branch
(RGB) stars and their radial distribution (RD) in Galactic globular clusters
(GCs). We relied on publicly available archival data on IA in red giants (RGs)
of GCs. We built a sample of ten target GCs in which the number of these RGs
exceeded one hundred stars. In each GC of the sample, we compared the RDs of
two sub-samples of stars, more iron-rich (IR) and more iron-poor (IP) than the
clusters' mean values of [Fe/H]. Their RDs turned out to be different at
statistically significant confidence levels in NGC 104 (47 Tuc), NGC 1851, NGC
3201, and NGC 6752 in the sense that the IP RGs were more centrally
concentrated than their IR counterparts. In 47 Tuc, the difference is
significant at a higher confidence level within the PRAD of R = 8.0', where the
IA increases by Delta[Fe/H] ~ 0.03 dex toward the cluster outskirts. In the
latter three GCs, Delta[Fe/H] ~ 0.05 dex. Interestingly, the V magnitude of the
RGB bump and the horizontal branch was recently shown to fade outward in 47 Tuc
and was suggested to originate from a He abundance trend. The fading caused by
the IA trend is similar to that observed for the RGB bump. Although the
difference between the RDs of IP and IR RGs is statistically insignificant in
other GCs, NGC 288 is the only GC of the sample, in which IR RGB stars are
formally more centrally concentrated. Interestingly, three of the four GCs are
highly concentrated. (Abridged)


title:
Constricted SUSY from No-Scale F-SU(5): A "Blind Spot" for LHC Top Quark
  Reconstruction?

abstract:
  We describe a region of the No-Scale F-SU(5) supersymmetric model with
TeV-scale vector-like matter multiplets that is potentially opaque to LHC
observations based upon top quark reconstruction. Possessing a 100% on-shell
branching fraction for gluino to light stop decays, the gluino-light stop mass
splitting in F-SU(5) lies very close to the top quark rest mass in the region
810 (650) <~ M(gluino) (M(light stop)) <~ 1170 (975) GeV. For unboosted gluino
pair-production, this could render two soft top quarks in the dominant 4-top
signature, greatly reducing the likelihood for discrimination from the
combinatoric background. We therefore suggest that caution is warranted when
gluino exclusion bounds on models possessing a similar spectral character
(gluino heavier than the light stop but lighter than all other squarks) using
multijet SUSY search tactics. Alternate search methods are highlighted,
including those based upon same sign dileptons and multiple heavy flavor tags,
which are more sensitive to this delicate kinematic "blind spot" crease.


title: Anomaly related transport of Weyl fermions for Weyl semi-metals

abstract:
  We present a field theoretical model of anomalous transport in Weyl
semi-metals. We calculate the Chiral Magnetic and Chiral Vortical Effect in the
electric, axial (valley) and energy current. Our findings coincide with the
results of a recent analysis using kinetic theory in the bulk of the material.
We point out that the kinetic currents have to be identified with the covariant
currents in quantum field theory. These currents are anomalous and the CME
appears as anomalous charge creation/annihilation at the edges of the Weyl
semi-metal. We discuss a possible simultaneous experimental test of the chiral
magnetic and the chiral vortical effect sensitive to the temperature dependence
induce by the gravitational contribution to the axial anomaly.


title:
A Nonparametric Approach for Multiple Change Point Analysis of
  Multivariate Data

abstract:
  Change point analysis has applications in a wide variety of fields. The
general problem concerns the inference of a change in distribution for a set of
time-ordered observations. Sequential detection is an online version in which
new data is continually arriving and is analyzed adaptively. We are concerned
with the related, but distinct, offline version, in which retrospective
analysis of an entire sequence is performed. For a set of multivariate
observations of arbitrary dimension, we consider nonparametric estimation of
both the number of change points and the positions at which they occur. We do
not make any assumptions regarding the nature of the change in distribution or
any distribution assumptions beyond the existence of the alpha-th absolute
moment, for some alpha in (0,2). Estimation is based on hierarchical clustering
and we propose both divisive and agglomerative algorithms. The divisive method
is shown to provide consistent estimates of both the number and location of
change points under standard regularity assumptions. We compare the proposed
approach with competing methods in a simulation study. Methods from cluster
analysis are applied to assess performance and to allow simple comparisons of
location estimates, even when the estimated number differs. We conclude with
applications in genetics, finance and spatio-temporal analysis.


title:
On the Corner Points of the Capacity Region of a Two-User Gaussian
  Interference Channel

abstract:
  This work considers the corner points of the capacity region of a two-user
Gaussian interference channel (GIC). In a two-user GIC, the rate pairs where
one user transmits its data at the single-user capacity (without interference),
and the other at the largest rate for which reliable communication is still
possible are called corner points. This paper relies on existing outer bounds
on the capacity region of a two-user GIC that are used to derive informative
bounds on the corner points of the capacity region. The new bounds refer to a
weak two-user GIC (i.e., when both cross-link gains in standard form are
positive and below 1), and a refinement of these bounds is obtained for the
case where the transmission rate of one user is within $\varepsilon > 0$ of the
single-user capacity. The bounds on the corner points are asymptotically tight
as the transmitted powers tend to infinity, and they are also useful for the
case of moderate SNR and INR. Upper and lower bounds on the gap (denoted by
$\Delta$) between the sum-rate and the maximal achievable total rate at the two
corner points are derived. This is followed by an asymptotic analysis analogous
to the study of the generalized degrees of freedom (where the SNR and INR
scalings are coupled such that $\frac{\log(\text{INR})}{\log(\text{SNR})} =
\alpha \geq 0$), leading to an asymptotic characterization of this gap which is
exact for the whole range of $\alpha$. The upper and lower bounds on $\Delta$
are asymptotically tight in the sense that they achieve the exact asymptotic
characterization. Improved bounds on $\Delta$ are derived for finite SNR and
INR, and their improved tightness is exemplified numerically.


title:
Derivative at s = 1 of the p-adic L-function of the symmetric square of
  a Hilbert modular form

abstract:
  Let p be an odd prime and F a totally real number field. Let f be a Hilbert
cuspidal eigenform of parallel weight 2, trivial Nebentypus and ordinary at p.
It is possible to construct a p-adic L-function which interpolates the complex
L-function associated to the symmetric square representation of f. This p-adic
L-function vanishes at s=1 even if the complex L-function does not. Assuming p
inert and f Steinberg at p, we give a formula for the p-adic derivative at s=1
of this p-adic L-function, generalizing unpublished work of Greenberg and
Tilouine. Under some hypotheses on the conductor of f we prove a particular
case of a conjecture of Greenberg on trivial zeros.


title: Light-front analysis of the Casimir effect

abstract:
  The Casimir force between conducting plates at rest in an inertial frame is
usually computed in equal-time quantization, the natural choice for the given
boundary conditions. We show that the well-known result obtained in this way
can also be obtained in light-front quantization. This differs from a
light-front analysis where the plates are at "rest" in an infinite momentum
frame, rather than an inertial frame; in that case, as shown by Lenz and
Steinbacher, the result does not agree with the standard result. As is usually
done, the analysis is simplified by working with a scalar field and periodic
boundary conditions, in place of the complexity of quantum electrodynamics. The
two key ingredients are a careful implementation of the boundary conditions,
following the work of Almeida et al. on oblique light-front coordinates, and
computation of the ordinary energy density, rather than the light-front energy
density. The analysis demonstrates that the physics of the effect is
independent of the coordinate choice, as it must be.


title: On the thermodynamics of periodic AdS black branes

abstract:
  We consider asymptotically AdS black brane solutions that are dual to CFTs
with periodic dependence on the spatial directions, arising from either a
spontaneous or an explicit breaking of translational symmetry. We derive a
simple expression for the variation of the free-energy with respect to changing
the periods. This explains some observations, based on numerics, that have
arisen in the explicit construction of thermodynamically preferred black holes
in the case that the spatial directions are infinite in extent and the symmetry
is spontaneously broken. It also leads to simple Smarr-type relations involving
the boundary stress tensor..


title:
Can communication power of separable correlations exceed that of
  entanglement resource?

abstract:
  The scenario of remote state preparation with shared correlated quantum state
and one bit of forward communication [B. Dakic et al. Nature Physics 8, 666-670
(2012)] is considered. The transmission efficiency is examined by considering
general encoding and decoding strategies. The importance of use of linear
fidelity is recognized. It is shown that separable states cannot exceed the
efficiency of entangled states in this protocol. It is proven however that such
a surprising phenomena may naturally occur when the decoding agent has limited
resources in the sense that either (i) has no information about the coordinates
in the sender plane being in question or (ii) is forced to use bistochastic
operations only which may be imposed by physically inconvenient local
thermodynamical conditions.


title: On the deformation of path algebras

abstract:
  Those elements of the second de Rham cohomology group of a connected,
oriented Riemannian manifold which map its second homotopy group to zero or to
a discrete subgroup of the reals induce deformations of the path algebra of the
manifold. If the image is not identically zero then the induced deformations
are quantized. We examine the simplest examples, namely, the torus and the
2-sphere, and consider possible physical interpretations of the deformations of
their path algebras.


title: Weak Rudin-Keisler reductions on projective ideals

abstract:
  We consider a slightly modified form of the standard Rudin-Keisler order on
ideals and demonstrate the existence of complete (with respect to this order)
ideals in various projective classes. Using our methods, we obtain a simple
proof of Hjorth's theorem on the existence of a complete $\mathbf \Pi^1_1$
equivalence relation. Our proof of Hjorth's theorem enables us (under PD) to
generalize his result to the classes of $\mathbf \Pi^1_{2n+1}$ equivalence
relations.


title: Upper and lower bounds on $B_k^+$-sets

abstract:
  Let $G$ be an abelian group. A set $A \subset G$ is a \emph{$B_k^+$-set} if
whenever $a_1 + \dots + a_k = b_1 + \dots + b_k$ with $a_i, b_j \in A$ there is
an $i$ and a $j$ such that $a_i = b_j$. If $A$ is a $B_k$-set then it is also a
$B_k^+$-set but the converse is not true in general. Determining the largest
size of a $B_k$-set in the interval $\{1, 2, \dots, N \} \subset \integers$ or
in the cyclic group $\integers_N$ is a well studied problem. In this paper we
investigate the corresponding problem for $B_k^+$-sets. We prove non-trivial
upper bounds on the maximum size of a $B_k^+$-set contained in the interval
$\{1, 2, \dots, N \}$. For odd $k \geq 3$, we construct $B_k^+$-sets that have
more elements than the $B_k$-sets constructed by Bose and Chowla. We prove a
$B_3^+$-set $A \subset \integers_N$ has at most $(1 + o(1))(8N)^{1/3}$
elements. Finally we obtain new upper bounds on the maximum size of a
$B_k^*$-set $A \subset \{1,2, \dots, N \}$, a problem first investigated by
Ruzsa.


title:
Disentangling electronic and vibronic coherences in two-dimensional echo
  spectra

abstract:
  The prevalence of long-lasting oscillatory signals in the 2d
echo-spectroscopy of light-harvesting complexes has led to a search for
possible mechanisms. We investigate how two causes of oscillatory signals are
intertwined: (i) electronic coherences supporting delocalized wave-like motion,
and (ii) narrow bands in the vibronic spectral density. To disentangle the
vibronic and electronic contributions we introduce a time-windowed Fourier
transform of the signal amplitude. We find that 2d spectra can be dominated by
excitations of pathways which are absent in excitonic energy transport. This
leads to an underestimation of the life-time of electronic coherences by 2d
spectra.


title: Failure of Calibration is Typical

abstract:
  Schervish (1985b) showed that every forecasting system is noncalibrated for
uncountably many data sequences that it might see. This result is strengthened
here: from a topological point of view, failure of calibration is typical and
calibration rare. Meanwhile, Bayesian forecasters are certain that they are
calibrated---this invites worries about the connection between Bayesianism and
rationality.


title: Contrastive Sets and Framing: A Case Study in Scientific Writing

abstract:
  I describe an activity created to help our students learn how to write a
scientific paper by reverse engineering a contrastive set of existing papers. I
look at three recent implementations of this activity and use a multiple
cognitive models approach to begin understanding the variance. This leads to a
reasonable strategy for further investigation. First, I describe the conception
and design of the activity structure, and how a contrastive set was
constructed. I create an initial coding scheme to characterize group behavior
in the three implementations, with special attention paid to analyzing student
dialog on the structure of scientific papers and their ideas about the reasons
for the peculiar features they observe. There is a striking difference in the
way students engaged with the activity between the implementations not all of
which can be ascribed to differences in activity structures, and the remainder
of the paper is concerned with the use of resources and framing, case-based
reasoning and Gibson's ecological perspective to understand the reason for this
difference.


title:
Performance of jet substructure techniques for large-R jets in
  proton-proton collisions at sqrt(s) = 7 TeV using the ATLAS detector

abstract:
  This paper presents the application of a variety of techniques to study jet
substructure. The performance of various modified jet algorithms, or jet
grooming techniques, for several jet types and event topologies is investigated
for jets with transverse momentum larger than 300 GeV. Properties of jets
subjected to the mass-drop filtering, trimming, and pruning algorithms are
found to have reduced sensitivity to multiple proton-proton interactions, are
more stable at high luminosity and improve the physics potential of searches
for heavy boosted objects. Studies of the expected discrimination power of jet
mass and jet substructure observables in searches for new physics are also
presented. Event samples enriched in boosted W and Z bosons and top-quark pairs
are used to study both the individual jet invariant mass scales and the
efficacy of algorithms to tag boosted hadronic objects. The analyses presented
use the full 2011 ATLAS dataset, corresponding to an integrated luminosity of
4.7 +/- 0.1 /fb from proton-proton collisions produced by the Large Hadron
Collider at a center-of-mass energy of sqrt(s) = 7 TeV.


title: Thermopower of few-electron quantum dots with Kondo correlations

abstract:
  The thermopower of few-electron quantum dots with Kondo correlations is
investigated via a hierarchial equations of motion approach. The thermopower is
determined by the line shape of spectral function within a narrow energy window
defined by temperature. Based on calculations and analyses on single-level and
two-level Anderson impurity models, the underlying relations between
thermopower and various types of electron correlations are elaborated. In
particular, an unconventional sign reversal behavior is predicted for quantum
dots with a suitable inter-level spacing. The new feature highlights the
significance of multi-level effects and their interplay with Kondo
correlations. Our finding and understanding may lead to novel thermoelectric
applications of quantum dots.


title: Machine Teaching for Bayesian Learners in the Exponential Family

abstract:
  What if there is a teacher who knows the learning goal and wants to design
good training data for a machine learner? We propose an optimal teaching
framework aimed at learners who employ Bayesian models. Our framework is
expressed as an optimization problem over teaching examples that balance the
future loss of the learner and the effort of the teacher. This optimization
problem is in general hard. In the case where the learner employs conjugate
exponential family models, we present an approximate algorithm for finding the
optimal teaching set. Our algorithm optimizes the aggregate sufficient
statistics, then unpacks them into actual teaching examples. We give several
examples to illustrate our framework.


title:
Limitations of the hybrid functional approach to electronic structure of
  transition metal oxides

abstract:
  During the last decade, ab initio methods to calculate electronic structure
of materials based on hybrid functionals are increasingly becoming widely
popular. In this Letter, we show that, in the case of small gap transition
metal oxides, such as VO2, with rather subtle physics in the vicinity of the
Fermi-surface, such hybrid functional schemes without the inclusion of
"expensive" fully self-consistent GW corrections fail to yield this physics and
incorrectly describe the features of the wave function of states near the
Fermi-surface. While a fully self-consistent GW on top of hybrid functional
approach does correct these wave functions as expected, and is found to be in
general agreement with the results of a fully self-consistent GW approach based
on semilocal functionals, it is much more computationally demanding as compared
to the latter approach for the benefit of essentially the same results.


title:
Minimizing Convergence Error in Multi-Agent Systems via Leader
  Selection: A Supermodular Optimization Approach

abstract:
  In a leader-follower multi-agent system (MAS), the leader agents act as
control inputs and influence the states of the remaining follower agents. The
rate at which the follower agents converge to their desired states, as well as
the errors in the follower agent states prior to convergence, are determined by
the choice of leader agents. In this paper, we study leader selection in order
to minimize convergence errors experienced by the follower agents, which we
define as a norm of the distance between the follower agents' intermediate
states and the convex hull of the leader agent states. By introducing a novel
connection to random walks on the network graph, we show that the convergence
error has an inherent supermodular structure as a function of the leader set.
Supermodularity enables development of efficient discrete optimization
algorithms that directly approximate the optimal leader set, provide provable
performance guarantees, and do not rely on continuous relaxations. We formulate
two leader selection problems within the supermodular optimization framework,
namely, the problem of selecting a fixed number of leader agents in order to
minimize the convergence error, as well as the problem of selecting the
minimum-size set of leader agents to achieve a given bound on the convergence
error. We introduce algorithms for approximating the optimal solution to both
problems in static networks, dynamic networks with known topology
distributions, and dynamic networks with unknown and unpredictable topology
distributions. Our approach is shown to provide significantly lower convergence
errors than existing random and degree-based leader selection methods in a
numerical study.


title:
Persistent Coherence and Spin-Polarization of Topological Surface States
  on Topological Insulators

abstract:
  Gapless surface states on topological insulators are protected from elastic
scattering on non-magnetic impurities which makes them promising candidates for
low-power electronic applications. However, for wide-spread applications, these
states should remain coherent and significantly spin polarized at ambient
temperatures. Here, we studied the coherence and spin-structure of the
topological states on the surface of a model topological insulator, Bi2Se3, at
elevated temperatures in spin and angle-resolved photoemission spectroscopy. We
found an extremely weak broadening and essentially no decay of spin
polarization of the topological surface state up to room temperature. Our
results demonstrate that the topological states on surfaces of topological
insulators could serve as a basis for room temperature electronic devices.


title:
Two photon exchange amplitude with \pi N intermediate states: P33
  channel

abstract:
  We consider two-photon exchange (TPE) in the elastic electron-proton
scattering and evaluate the effect of \pi N (pion + nucleon) intermediate
hadronic states. Among different \pi N states, we concentrate on the P33
channel; thus we effectively include Delta(1232) resonance with realistic width
and shape and corresponding background as well. In agreement with the previous
result, obtained for the zero-width resonance, we observe that the TPE
correction to the electric form factor is the largest one; it grows with Q^2
and at Q^2 > 2.5 GeV^2 exceeds the corresponding elastic contribution.


title: Hertz Beyond Belief

abstract:
  We examine the validity of Hertz's linear elastic theory for central
collisions using a viscoelastic model. This model explains why Hertz's theory
is accurate in predicting the collision time and maximum contact area even when
$40\%$ of the kinetic energy is lost due to viscous dissipation. The main
reason is that both the collision time and maximum contact area have a very
weak dependence on the impact velocity. Moreover, we show that colliding
objects exhibit an apparent size dependent yield strength, which results from
larger objects dissipating less energy at a given impact velocity.


title:
Implementation of a simplified approach to radiative transfer in general
  relativity

abstract:
  We describe in detail the implementation of a simplified approach to
radiative transfer in general relativity by means of the well-known neutrino
leakage scheme (NLS). In particular, we carry out an extensive investigation of
the properties and limitations of the NLS for isolated relativistic stars to a
level of detail that has not been discussed before in a general-relativistic
context. Although the numerous tests considered here are rather idealized, they
provide a well-controlled environment in which to understand the relationship
between the matter dynamics and the neutrino emission, which is important in
order to model the neutrino signals from more complicated scenarios, such as
binary neutron-star mergers. When considering nonrotating hot neutron stars we
confirm earlier results of one-dimensional simulations, but also present novel
results about the equilibrium properties and on how the cooling affects the
stability of these configurations. In our idealized but controlled setup, we
can then show that deviations from the thermal and weak-interaction equilibrium
affect the stability of these models to radial perturbations, leading models
that are stable in the absence of radiative losses, to a gravitational collapse
to a black hole when neutrinos are instead radiated.


title: Next decade of sterile neutrino studies

abstract:
  We review the status of sterile neutrino dark matter and discuss
astrophysical and cosmological bounds on its properties as well as future
prospects for its experimental searches. We argue that if sterile neutrinos are
the dominant fraction of dark matter, detecting an astrophysical signal from
their decay (the so-called 'indirect detection') may be the only way to
identify these particles experimentally. However, it may be possible to check
the dark matter origin of the observed signal unambiguously using its
characteristic properties and/or using synergy with accelerator experiments,
searching for other sterile neutrinos, responsible for neutrino flavor
oscillations. We argue that to fully explore this possibility a dedicated
cosmic mission - an X-ray spectrometer - is needed.


title: Large N Phase Transitions, Finite Volume, and Entanglement Entropy

abstract:
  Holographic studies of the entanglement entropy of field theories dual to
charged and neutral black holes in asymptotically global AdS4 spacetimes are
presented. The goal is to elucidate various properties of the quantity that are
peculiar to working in finite volume, and to gain access to the behaviour of
the entanglement entropy in the rich thermodynamic phase structure that is
present at finite volume and large N. The entropy is followed through various
first order phase transitions, and also a novel second order phase transition.
Properties of a specific heat in the neighbourhood of the critical point are
computed. Behaviour is found that contrasts interestingly with an earlier
holographic study of a second order phase transition dual to an holographic
superconductor.


title:
Cloud-Based Augmentation for Mobile Devices: Motivation, Taxonomies, and
  Open Challenges

abstract:
  Recently, Cloud-based Mobile Augmentation (CMA) approaches have gained
remarkable ground from academia and industry. CMA is the state-of-the-art
mobile augmentation model that employs resource-rich clouds to increase,
enhance, and optimize computing capabilities of mobile devices aiming at
execution of resource-intensive mobile applications. Augmented mobile devices
envision to perform extensive computations and to store big data beyond their
intrinsic capabilities with least footprint and vulnerability. Researchers
utilize varied cloud-based computing resources (e.g., distant clouds and nearby
mobile nodes) to meet various computing requirements of mobile users. However,
employing cloud-based computing resources is not a straightforward panacea.
Comprehending critical factors that impact on augmentation process and optimum
selection of cloud-based resource types are some challenges that hinder CMA
adaptability. This paper comprehensively surveys the mobile augmentation domain
and presents taxonomy of CMA approaches. The objectives of this study is to
highlight the effects of remote resources on the quality and reliability of
augmentation processes and discuss the challenges and opportunities of
employing varied cloud-based resources in augmenting mobile devices. We present
augmentation definition, motivation, and taxonomy of augmentation types,
including traditional and cloud-based. We critically analyze the
state-of-the-art CMA approaches and classify them into four groups of distant
fixed, proximate fixed, proximate mobile, and hybrid to present a taxonomy.
Vital decision making and performance limitation factors that influence on the
adoption of CMA approaches are introduced and an exemplary decision making
flowchart for future CMA approaches are presented. Impacts of CMA approaches on
mobile computing is discussed and open challenges are presented as the future
research directions.


title:
Exchange-Correlation Energy from Pairing Matrix Fluctuation and the
  Particle-Particle Random Phase Approximation

abstract:
  We formulate an adiabatic connection for the exchange-correlation energy in
terms of pairing matrix fluctuation. This connection opens new channels for
density functional approximations based on pairing interactions. Even the
simplest approximation to the pairing matrix fluctuation, the particle-particle
Random Phase Approximation (pp-RPA), has some highly desirable properties. It
has no delocalization error with a nearly linear energy behavior for systems
with fractional charges, describes van der Waals interactions similarly and
thermodynamic properties significantly better than particle-hole RPA, and
eliminates static correlation error for single-bond systems. Most
significantly, the pp-RPA is the first known functional that has an explicit
and closed-form dependence on the occupied and unoccupied orbitals and captures
the energy derivative discontinuity in strongly correlated systems. These
findings illlustrate the potential of including pairing interactions within a
density functional framework.


title:
Hedging and Leveraging: Principal Portfolios of the Capital Asset
  Pricing Model

abstract:
  The principal portfolios of the standard Capital Asset Pricing Model (CAPM)
are analyzed and found to have remarkable hedging and leveraging properties.
Principal portfolios implement a recasting of any correlated asset set of N
risky securities into an equivalent but uncorrelated set when short sales are
allowed. While a determination of principal portfolios in general requires a
detailed knowledge of the covariance matrix for the asset set, the rather
simple structure of CAPM permits an accurate solution for any reasonably large
asset set that reveals interesting universal properties. Thus for an asset set
of size N, we find a market-aligned portfolio, corresponding to the market
portfolio of CAPM, as well as N-1 market-orthogonal portfolios which are market
neutral and strongly leveraged. These results provide new insight into the
return-volatility structure of CAPM, and demonstrate the effect of unbridled
leveraging on volatility.


title: Ultradiscrete Painlev\'e VI with Parity Variables

abstract:
  We introduce a ultradiscretization with parity variables of the
$q$-difference Painlev\'e VI system of equations. We show that ultradiscrete
limit of Riccati-type solutions of $q$-Painlev\'e VI satisfies the
ultradiscrete Painlev\'e VI system of equations with the parity variables,
which is valid by using the parity variables. We study some solutions of the
ultradiscrete Riccati-type equation and those of ultradiscrete Painlev\'e VI
equation.


title:
Optimal computational and statistical rates of convergence for sparse
  nonconvex learning problems

abstract:
  We provide theoretical analysis of the statistical and computational
properties of penalized $M$-estimators that can be formulated as the solution
to a possibly nonconvex optimization problem. Many important estimators fall in
this category, including least squares regression with nonconvex
regularization, generalized linear models with nonconvex regularization and
sparse elliptical random design regression. For these problems, it is
intractable to calculate the global solution due to the nonconvex formulation.
In this paper, we propose an approximate regularization path-following method
for solving a variety of learning problems with nonconvex objective functions.
Under a unified analytic framework, we simultaneously provide explicit
statistical and computational rates of convergence for any local solution
attained by the algorithm. Computationally, our algorithm attains a global
geometric rate of convergence for calculating the full regularization path,
which is optimal among all first-order algorithms. Unlike most existing methods
that only attain geometric rates of convergence for one single regularization
parameter, our algorithm calculates the full regularization path with the same
iteration complexity. In particular, we provide a refined iteration complexity
bound to sharply characterize the performance of each stage along the
regularization path. Statistically, we provide sharp sample complexity analysis
for all the approximate local solutions along the regularization path. In
particular, our analysis improves upon existing results by providing a more
refined sample complexity bound as well as an exact support recovery result for
the final estimator. These results show that the final estimator attains an
oracle statistical property due to the usage of nonconvex penalty.


title: Prospects of Focus Point Supersymmetry for Snowmass 2013

abstract:
  We briefly review the motivations and features of focus point supersymmetry
and in particular the focus point region of the CMSSM. Applying the constraint
that the neutralino is a thermal relic, we examine current and projected
collider and dark matter constraints on the focus point region. We demonstrate
that the focus point region is currently constrained by multiple dark matter
experiments, and future sensitivy on multiple fronts will probe large portions
of the parameter space.


title:
An Exploratory Ethnographic Study of Issues and Concerns with Whole
  Genome Sequencing

abstract:
  Progress in Whole Genome Sequencing (WGS) will soon allow a large number of
individuals to have their genome fully sequenced. This lays the foundations to
improve modern healthcare, enabling a new era of personalized medicine where
diagnosis and treatment is tailored to the patient's genetic makeup. It also
allows individuals motivated by personal curiosity to have access to their
genetic information, and use it, e.g., to trace their ancestry. However, the
very same progress also amplifies a number of ethical and privacy concerns,
that stem from the unprecedented sensitivity of genomic information and that
are not well studied. This paper presents an exploratory ethnographic study of
users' perception of privacy and ethical issues with WGS, as well as their
attitude toward different WGS programs. We report on a series of
semi-structured interviews, involving 16 participants, and analyze the results
both quantitatively and qualitatively. Our analysis shows that users exhibit
common trust concerns and fear of discrimination, and demand to retain strict
control over their genetic information. Finally, we highlight the need for
further research in the area and follow-up studies that build on our initial
findings.


title: Galaxy and Mass Assembly (GAMA): galaxy radial alignments in GAMA groups

abstract:
  We constrain the distributions of projected radial alignment angles of
satellite galaxy shapes within the Galaxy And Mass Assembly survey group
catalogue. We identify the galaxy groups using spectroscopic redshifts and
measure galaxy projected ellipticities from Sloan Digital Sky Survey imaging.
With a sample of 3,850 groups with 13,655 satellite galaxies with high quality
shape measurements, we find a less than 2-sigma signal of radial alignments in
the mean projected ellipticity components and the projected position angle when
using galaxy shape estimates optimized for weak lensing measurements. Our
radial alignment measurement increases to greater than 3-sigma significance
relative to the expectation for no alignments if we use 2-D S\'ersic model fits
to define galaxy orientations. Our weak measurement of radial alignments is in
conflict with predictions from dark matter N-body simulations, which we
interpret as evidence for large mis-alignments of baryons and dark matter in
group and cluster satellites. Within our uncertainties, that are dominated by
our small sample size, we find only weak and marginally significant trends of
the radial alignment angle distributions on projected distance from the group
centre, host halo mass, and redshift that could be consistent with a tidal
torquing mechanism for radial alignments. Using our lensing optimized shape
estimators, we estimate that intrinsic alignments of galaxy group members may
contribute a systematic error to the mean differential projected surface mass
density of groups inferred from weak lensing observations by -1 +/- 20% at
scales around 300 kpc/h from the group centre assuming a photometric redshift
r.m.s. error of 10%, and given our group sample with median redshift of 0.17
and median virial masses ~10^{13} h^{-1}M_{sun}.


title:
Equivalent teleparallel theories in diagonalizable spacetimes: Comment
  on "Metric-affine approach to teleparallel gravity"

abstract:
  It is well known that the teleparallel equivalent of general relativity
yields the same vacuum solutions as general relativity does, which ensures that
this particular teleparallel model is in good agreement with experiments. A
less known result concerns the existence of a wider class of teleparallel
models which also admits these solutions when the spacetime is diagonalizable
by means of a coordinate change. However, it is stated in Ref. [Phys. Rev. D
67, 044016 (2003).] that the teleparallel equivalent of general relativity is
the only teleparallel model which admits black holes. To show that this
statement is not true, I prove the existence of this wider class by taking an
approach different from that of Ref. [Phys. Rev. D 19, 3524 (1979)].


title: Threading Dynamics of Ring Polymers in a Gel

abstract:
  We perform large scale three-dimensional molecular dynamics simulations of
unlinked and unknotted ring polymers diffusing through a background gel, here a
three-dimensional cubic lattice. Taking advantage of this architecture, we
propose a new method to unambiguously identify and quantify inter-ring
threadings (penetrations) and to relate these to the dynamics of the ring
polymers. We find that both the number and the persistence time of the
threadings increase with the length of the chains, ultimately leading to a
percolating network of inter-ring penetrations. We discuss the implications of
these findings for the possible emergence of a topological jammed state of very
long rings.


title: Determining Points on Handwritten Mathematical Symbols

abstract:
  In a variety of applications, such as handwritten mathematics and diagram
labelling, it is common to have symbols of many different sizes in use and for
the writing not to follow simple baselines. In order to understand the scale
and relative positioning of individual characters, it is necessary to identify
the location of certain expected features. These are typically identified by
particular points in the symbols, for example, the baseline of a lower case "p"
would be identified by the lowest part of the bowl, ignoring the descender. We
investigate how to find these special points automatically so they may be used
in a number of problems, such as improving two-dimensional mathematical
recognition and in handwriting neatening, while preserving the original style.


title: Unitarity of the SoV transform for the Toda chain

abstract:
  The quantum separation of variables method consists in mapping the original
Hilbert space where a spectral problem is formulated onto one where the
spectral problem takes a simpler "separated" form. In order to realise such a
program, one should construct the map explicitly and then show that it is
unitary.
  In the present paper, we develop a technique which allows one to prove the
unitarity of this map in the case of the quantum Toda chain. Our proof solely
builds on objects and relations naturally arising in the framework of the
so-called quantum inverse scattering method. Hence, with minor modifications,
it should be readily transposable to other quantum integrable models solvable
by the quantum separation of variables method. As such, it provides an
important alternative to the proof of the map's unitarity based on the group
theoretical interpretation of the quantum Toda chain, which is absent for more
complex quantum integrable models.


title:
The ALHAMBRA Survey: Bayesian Photometric Redshifts with 23 bands for 3
  squared degrees

abstract:
  The ALHAMBRA (Advance Large Homogeneous Area Medium Band Redshift
Astronomical) survey has observed 8 different regions of the sky, including
sections of the COSMOS, DEEP2, ELAIS, GOODS-N, SDSS and Groth fields using a
new photometric system with 20 contiguous ~ $300\AA$ filters covering the
optical range, combining them with deep $JHKs$ imaging. The observations,
carried out with the Calar Alto 3.5m telescope using the wide field (0.25 sq.
deg FOV) optical camera LAICA and the NIR instrument Omega-2000, correspond to
~700hrs on-target science images. The photometric system was designed to
maximize the effective depth of the survey in terms of accurate spectral-type
and photo-zs estimation along with the capability of identification of
relatively faint emission lines. Here we present multicolor photometry and
photo-zs for ~438k galaxies, detected in synthetic F814W images, complete down
to I~24.5 AB, taking into account realistic noise estimates, and correcting by
PSF and aperture effects with the ColorPro software. The photometric ZP have
been calibrated using stellar transformation equations and refined internally,
using a new technique based on the highly robust photometric redshifts measured
for emission line galaxies. We calculate photometric redshifts with the BPZ2
code, which includes new empirically calibrated templates and priors. Our
photo-zs have a precision of $dz/(1+z_s)=1%$ for I<22.5 and 1.4% for
22.5<I<24.5. Precisions of less than 0.5% are reached for the brighter
spectroscopic sample, showing the potential of medium-band photometric surveys.
The global $P(z)$ shows a mean redshift <z>=0.56 for I<22.5 AB and <z>=0.86 for
I<24.5 AB. The data presented here covers an effective area of 2.79 sq. deg,
split into 14 strips of 58.5'x15.5' and represents ~32 hrs of on-target.


title: Connecting the Pygmy Dipole Resonance to the neutron skin

abstract:
  We study the correlation between the neutron skin development and the
low-energy dipole response associated with the pygmy dipole resonance (PDR) in
connection with the properties of symmetry energy. We perform our investigation
within a microscopic transport model based on the Landau-Vlasov kinetic
equation by employing three different equations of state in the isovector
sector. Together with the giant dipole resonance (GDR) for all studied systems,
we identify a PDR collective mode whose energy centroid is very well described
by the parametrization E_{PDR}=41 A^{-1/3}. A linear correlation between the
energy weighted sum rule (EWSR) associated to PDR and the neutron skin
thickness is evidenced. An increase of 15 MeVfm^2 of EWSR, in correspondence to
a change of 0.1fm of the neutron skin size, is obtained. We conjecture that
different nuclei having close neutron skin sizes will exhaust the same EWSR in
the pygmy region. This suggests that a precise experimental estimate of the
total EWSR exhausted by the PDR allows the determination of the neutron skin
size, constraining the slope parameter of the symmetry energy.


title: Dispersive approach to QCD and inclusive tau lepton hadronic decay

abstract:
  The dispersive approach to QCD is applied to the study of the inclusive tau
lepton hadronic decay. This approach provides the unified integral
representations for the hadronic vacuum polarization function, related R
function, and Adler function. These representations account for the
intrinsically nonperturbative constraints, which originate in the kinematic
restrictions on the functions on hand, and retain the effects due to
hadronization, which play a valuable role in the analysis of the strong
interaction processes at low energies. The dispersive approach proves to be
capable of describing recently updated ALEPH and OPAL experimental data on
inclusive tau lepton hadronic decay in vector and axial-vector channels. The
vicinity of values of the QCD scale parameter obtained in both channels
testifies to the potential ability of the developed approach to describe the
aforementioned data in a self-consistent way.


title: A "kilonova" associated with short-duration gamma-ray burst 130603B

abstract:
  Short-duration gamma-ray bursts (SGRBs) are intense flashes of cosmic
gamma-rays, lasting less than ~2 s, whose origin is one of the great unsolved
questions of astrophysics today. While the favoured hypothesis for their
production, a relativistic jet created by the merger of two compact stellar
objects (specifically, two neutron stars, NS-NS, or a neutron star and a black
hole, NS-BH), is supported by indirect evidence such as their host galaxy
properties, unambiguous confirmation of the model is still lacking. Mergers of
this kind are also expected to create significant quantities of neutron-rich
radioactive species, whose decay should result in a faint transient in the days
following the burst, a so-called "kilonova". Indeed, it is speculated that this
mechanism may be the predominant source of stable r-process elements in the
Universe. Recent calculations suggest much of the kilonova energy should appear
in the near-infrared (nIR) due to the high optical opacity created by these
heavy r-process elements. Here we report strong evidence for such an event
accompanying SGRB 130603B. If this simplest interpretation of the data is
correct, it provides (i) support for the compact object merger hypothesis of
SGRBs, (ii) confirmation that such mergers are likely sites of significant
r-process production and (iii) quite possibly an alternative, un-beamed
electromagnetic signature of the most promising sources for direct detection of
gravitational waves.


title: Ballistic Heat Transfer and Energy Waves in an Electron System

abstract:
  Materials in which heat and entropy can be transmitted by directed ballistic
pulses can trigger new approaches to energy transduction in solids. We predict
that a ballistic energy transfer mode, with heat propagation governed by a wave
equation rather than a diffusion equation, can be realized for a thermal
electron-hole plasma in graphene. The new behavior originates from rapid
exchange of energy and momentum in particle collisions leading to energy
propagation as a collective weakly-damped oscillation. Due to the electronic
nature of this mode, the estimated propagation velocity can be ~10^3 times
larger than that for previously studied phonon mechanisms. The energy mode is
uncharged at charge neutrality, but becomes coupled to charge dynamics upon
doping. This coupling can be used for all-electric excitation and detection of
energy transport.


title: Strichartz estimates for Schr\"odinger equations on irrational tori

abstract:
  In this paper, we prove new Strichartz estimates for linear Schrodinger
equations posed on d-dimensional irrational tori. Then, we use these estimates
to prove subcritical and critical local well-posedness results for nonlinear
Schrodinger equations (NLS) on irrational tori.


title: Dynamical entanglement entropy with angular momentum and U(1) charge

abstract:
  We consider time-dependent entanglement entropy (EE) for a 1+1 dimensional
CFT in the presence of angular momentum and U(1) charge. The EE saturates,
irrespective of the initial state, to the grand canonical entropy after a time
large compared with the length of the entangling interval. We reproduce the CFT
results from an AdS dual consisting of a spinning BTZ black hole and a flat
U(1) connection. The apparent discrepancy that the holographic EE does not a
priori depend on the U(1) charge while the CFT EE does, is resolved by the
charge-dependent shift between the bulk and boundary stress tensors. We show
that for small entangling intervals, the entanglement entropy obeys the first
law of thermodynamics, as conjectured recently. The saturation of the EE in the
field theory is shown to follow from a version of quantum ergodicity; the
derivation indicates that it should hold for conformal as well as massive
theories in any number of dimensions.


title: A Stochastic Feedback Model for Volatility

abstract:
  Financial time series exhibit a number of interesting properties that are
difficult to explain with simple models. These properties include fat-tails in
the distribution of price fluctuations (or returns) that are slowly removed at
longer timescales, strong autocorrelations in absolute returns but zero
autocorrelation in returns themselves, and multifractal scaling. Although the
underlying cause of these features is unknown, there is growing evidence they
originate in the behavior of volatility, i.e., in the behavior of the magnitude
of price fluctuations. In this paper, we posit a feedback mechanism for
volatility that closely reproduces the non-trivial properties of empirical
prices. The model is parsimonious, contains only two parameters that are easily
estimated, fits empirical data better than standard models, and can be grounded
in a straightforward framework where volatility fluctuations are driven by the
estimation error of an exogenous Poisson rate.


title:
Chiral Luttinger liquids and a generalized Luttinger's theorem in
  fractional quantum Hall edges via finite-entanglement scaling

abstract:
  We use bosonic field theories and the infinite system density matrix
renormalization group (iDMRG) method to study infinite strips of fractional
quantum Hall (FQH) states starting from microscopic Hamiltonians.
Finite-entanglement scaling allows us to accurately measure chiral central
charge, edge mode exponents and momenta without finite-size errors. We analyze
states in the first and second level of the standard hierarchy and compare our
results to predictions of the chiral Luttinger liquid ($\chi$LL) theory. The
results confirm the universality of scaling exponents in chiral edges and
demonstrate that renormalization is subject to universal relations in the
non-chiral case. We prove a generalized Luttinger's theorem involving all
singularities in the momentum-resolved density, which naturally arises when
mapping Landau levels on a cylinder to a fermion chain and deepens our
understanding of non-Fermi liquids in 1D.


title:
Creating the Universe Without a Singularity and the Cosmological
  Constant Problem

abstract:
  We consider a non singular origin for the Universe starting from an Einstein
static Universe in the framework of a theory which uses two volume elements
$\sqrt{-{g}}d^{4}x$ and $\Phi d^{4}x$, where $\Phi $ is a metric independent
density, also curvature, curvature square terms, first order formalism and for
scale invariance a dilaton field $\phi$ are considered in the action. In the
Einstein frame we also add a cosmological term that parametrizes the zero point
fluctuations. The resulting effective potential for the dilaton contains two
flat regions, for $\phi \rightarrow \infty$ relevant for the non singular
origin of the Universe and $\phi \rightarrow -\infty$, describing our present
Universe. Surprisingly, avoidance of singularities and stability as $\phi
\rightarrow \infty$ imply a positive but small vacuum energy as $\phi
\rightarrow -\infty$. Zero vacuum energy density for the present universe is
the "threshold" for universe creation. This requires a modified emergent
universe scenario, where the universe although very old, it does have a
beginning.


title:
Linear flutter analysis of functionally graded panels using cell based
  smoothed finite element method and discrete shear gap technique

abstract:
  In this paper, a cell-based smoothed finite element method with discrete
shear gap technique for triangular ele- ments is employed to study the linear
flutter characteristics of functionally graded material (FGM) flat panels. The
influence of thermal environment, the presence of a centrally located circular
cutout and the aerodynamic damping on the supersonic flutter characteristics of
flat FGM panels is also investigated. The structural for- mulation is based on
the first-order shear deformation theory and the material properties are
assumed to be temperature dependent and graded only in the thickness direction
according to power law distribution in terms of the volume fraction of its
constituent materials. The aerodynamic force is evaluated by considering the
first order high mach number approximation to linear potential flow theory. The
formulation includes transverse shear deformation and in-plane and rotary
inertia effects. The influence of the plate thickness, aspect ratio, boundary
conditions, material gradient index, temperature dependent material properties,
damping, cutout size, skewness of the plate and boundary conditions on the
critical aerodynamic pressure is numerically studied.


title:
Constraints on corrections to Newtonian gravity from two recent
  measurements of the Casimir interaction between metallic surfaces

abstract:
  We obtain constraints on parameters of the Yukawa-type corrections to
Newton's gravitational law from measurements of the gradient of the Casimir
force between surfaces coated with ferromagnetic metal Ni and from measurements
of the Casimir force between Au-coated sinusoidally corrugated surfaces at
various angles between corrugations. It is shown that constraints following
from the experiment with magnetic surfaces are slightly weaker than currently
available strongest constraints, but benefit from increased reliability and
independence of systematic effects.The constraints derived from the experiment
with corrugated surfaces within the interaction region from 11.6 to 29.2\,nm
are stronger up to a factor of 4 than the strongest constraints derived from
other experiments. The possibility of further strengthening of constraints on
non-Newtonian gravity by using the configurations with corrugated boundaries is
proposed.


title:
CANDELS: The correlation between galaxy morphology and star formation
  activity at z~2

abstract:
  We discuss the state of the assembly of the Hubble Sequence in the mix of
bright galaxies at redshift 1.4< z \le 2.5 with a large sample of 1,671
galaxies down to H_{AB}~26, selected from the HST/ACS and WFC3 images of the
GOODS--South field obtained as part of the GOODS and CANDELS observations. We
investigate the relationship between the star formation properties and
morphology using various parametric diagnostics, such as the Sersic light
profile, Gini (G), M_{20}, Concentration (C), Asymmetry (A) and multiplicity
parameters. Our sample clearly separates into massive, red and passive galaxies
versus less massive, blue and star forming ones, and this dichotomy correlates
very well with the galaxies' morphological properties. Star--forming galaxies
show a broad variety of morphological features, including clumpy structures and
bulges mixed with faint low surface brightness features, generally
characterized by disky-type light profiles. Passively evolving galaxies, on the
other hand, very often have compact light distribution and morphology typical
of today's spheroidal systems. We also find that artificially redshifted local
galaxies have a similar distribution with z~2galaxies in a G-M_{20} plane.
Visual inspection between the rest-frame optical and UV images show that there
is a generally weak morphological k-correction for galaxies at z~2, but the
comparison with non-parametric measures show that galaxies in the rest-frame UV
are somewhat clumpier than rest-frame optical. Similar general trends are
observed in the local universe among massive galaxies, suggesting that the
backbone of the Hubble sequence was already in place at z~2.


title: Mathieu Moonshine and N=2 String Compactifications

abstract:
  There is a `Mathieu moonshine' relating the elliptic genus of K3 to the
sporadic group M_{24}. Here, we give evidence that this moonshine extends to
part of the web of dualities connecting heterotic strings compactified on K3
\times T^2 to type IIA strings compactified on Calabi-Yau threefolds. We
demonstrate that dimensions of M_{24} representations govern the new
supersymmetric index of the heterotic compactifications, and appear in the
Gromov--Witten invariants of the dual Calabi-Yau threefolds, which are elliptic
fibrations over the Hirzebruch surfaces F_n.


title:
Parametrizing the exoplanet eccentricity distribution with the Beta
  distribution

abstract:
  It is suggested that the distribution of orbital eccentricities for
extrasolar planets is well-described by the Beta distribution. Several
properties of the Beta distribution make it a powerful tool for this purpose.
For example, the Beta distribution can reproduce a diverse range of probability
density functions (PDFs) using just two shape parameters (a and b). We argue
that this makes it ideal for serving as a parametric model in Bayesian
comparative population analysis. The Beta distribution is also uniquely defined
over the interval zero to unity, meaning that it can serve as a proper prior
for eccentricity when analysing the observations of bound extrasolar planets.
Using nested sampling, we find that the distribution of eccentricities for 396
exoplanets detected through radial velocity with high signal-to-noise is
well-described by a Beta distribution with parameters a = 0.867+/-0.044 and b =
3.03+/-0.17. The Beta distribution is shown to be 3.7 times more likely to
represent the underlying distribution of exoplanet eccentricities than the next
best model: a Rayleigh + exponential distribution. The same data are also used
in an example population comparison utilizing the Beta distribution, where we
find that the short- and long-period planets are described by distinct Beta
distributions at a confidence of 11.6 sigma and display a signature consistent
with the effects of tidal circularization.


title: A giant elliptical galaxy with a lightweight initial mass function

abstract:
  We present new VLT observations of the closest-known strong-lensing galaxy,
the sigma=330 km/s giant elliptical ESO325-G004. The low redshift of the lens
(z_lens=0.035) results in arcs being formed at a small fraction of the
effective radius, (R_Ein ~ R_Eff/4). At such small radii, stars dominate the
lensing mass, so that lensing provides a direct probe of the stellar
mass-to-light ratio, with only small corrections needed for dark matter. The
redshift of the galaxy lensed by ESO325-G004 was unknown until now, so the
lensing mass was not securely determined. Using X-SHOOTER, we measure a secure
source redshift of z_src=2.141. Combined with the lensing configuration, this
yields a total mass inside the Einstein radius of (1.50+/-0.06) 10^11 M_sun. We
estimate the range of possible contribution of dark matter to the lensing mass,
using statistics from cosmological N-body simulations. Subtracting this
component yields a stellar M/L ratio for the lens of 3.14^+0.24_-0.42 (M/L)_sun
(in F814W band). Using VIMOS, we have also obtained very high-S/N spectroscopy
for the lens galaxy. The VIMOS data confirm that ESO325-G004 has a very old
stellar population. For a Kroupa IMF, the stellar population fit yields a
predicted stellar M/L ratio of 3.01+/-0.25 (M/L)_sun. Hence the mass
attributable to stars with this IMF is consistent with the lensing estimate. By
contrast, a Salpeter or heavier IMF is disfavoured at the 99.8% confidence
level. A "heavyweight" IMF, with a mass twice as large as the Kroupa case, is
firmly excluded. Such an IMF has been proposed for more distant elliptical
lenses, and also to explain strong dwarf-star spectral features, in particular
the NaI 8200-Ang doublet. A FORS2 far-red spectrum shows that this feature is
as strong in ESO325-G004 as it is in other high-sigma ellipticals, suggesting
tension between dwarf-star indicators and lensing-mass constraints for this
galaxy.


title: Detectability of the First Cosmic Explosions

abstract:
  We present a fully self-consistent simulation of a synthetic survey of the
furthermost cosmic explosions. The appearance of the first generation of stars
(Population III) in the Universe represents a critical point during cosmic
evolution, signaling the end of the dark ages, a period of absence of light
sources. Despite their importance, there is no confirmed detection of
Population III stars so far. A fraction of these primordial stars are expected
to die as pair-instability supernovae (PISNe), and should be bright enough to
be observed up to a few hundred million years after the big bang. While the
quest for Population III stars continues, detailed theoretical models and
computer simulations serve as a testbed for their observability. With the
upcoming near-infrared missions, estimates of the feasibility of detecting
PISNe are not only timely but imperative. To address this problem, we combine
state-of-the-art cosmological and radiative simulations into a complete and
self-consistent framework, which includes detailed features of the
observational process. We show that a dedicated observational strategy using
$\lesssim 8$ per cent of total allocation time of the James Webb Space
Telescope mission can provide us up to $\sim 9-15$ detectable PISNe per year.


title:
The case against large intensity fluctuations in the z ~ 2.5 HeII
  Lyman-alpha forest

abstract:
  Previous studies of the 2.2 < z< 2.7 HeII Lyman-alpha forest measured much
larger ionizing background fluctuations than are anticipated theoretically. We
re-analyze recent Hubble Space Telescope data from the two HeII sightlines that
have been used to make these measurements, HE2347-4342 and HS1700+6416, and
find that the vast majority of the absorption is actually consistent with a
single HeII photoionization rate. We show that the data constrains the RMS
fractional fluctuation level smoothed at 1 Mpc to be < 2 and discuss why other
studies had found larger fluctuations. Our measurement is consistent with
models in which quasars dominate the z=2.5 metagalactic HeII-ionizing
background (but it can accommodate less compelling models), and it suggests
that quasars (rather than stars) are the dominant contributor to the
HI-ionizing background. We detect a HeII transverse proximity effect that is
slightly offset in redshift from a known quasar. Its profile and offset may
indicate that the quasar turned on 10 Myr ago.


title: Dynamics of thermalization and decoherence of a nanoscale system

abstract:
  We study the decoherence and thermalization dynamics of a nanoscale system
coupled nonperturbatively to a fully quantum-mechanical bath. The system is
prepared out of equilibrium in a pure state of the complete system. We propose
a random matrix model and show analytically that there are two robust temporal
regimes in the approach of the system to equilibrium --- an initial Gaussian
decay followed by an exponential tail, consistent with numerical results on
small interacting lattices [S. Genway, A.F. Ho and D.K.K. Lee, Phys. Rev. Lett.
105, 260402 (2010)]. Furthermore, the system decays towards a Gibbs ensemble in
accordance with the eigenstate thermalization hypothesis.


title:
Search for Supermassive Black Hole Binaries in the Sloan Digital Sky
  Survey Spectroscopic Sample

abstract:
  Supermassive black hole (SMBH) binaries are expected in a Lambda CDM
cosmology given that most (if not all) massive galaxies contain a massive black
hole at their center. So far, however, direct evidence for such binaries has
been elusive. We use cross-correlation to search for temporal velocity shifts
in the MgII broad emission lines of 0.36 < z < 2 quasars with multiple
observations in the Sloan Digital Sky Survey. For ~ 10^9 Msun BHs in SMBH
binaries, we are sensitive to velocity drifts for binary separations of ~ 0.1
pc with orbital periods of ~100 years. We find seven candidate sub-pc--scale
binaries with velocity shifts > 3.4 sigma ~ 280 km/s, where sigma is our
systematic error. Comparing the detectability of SMBH binaries with the number
of candidates (N < 7), we can rule out that most 10^9 Msun BHs exist in ~
0.03-0.2 pc scale binaries, in a scenario where binaries stall at sub-pc scales
for a Hubble time. We further constrain that < one-third of quasars host SMBH
binaries after considering gas-assisted sub-pc evolution of SMBH binaries,
although this result is very sensitive to the assumed size of the broad line
region. We estimate the detectability of SMBH binaries with ongoing or
next-generation surveys (e.g., BOSS, Subaru Prime Focus Spectrograph), taking
into account the evolution of the sub-parsec binary in circumbinary gas disks.
These future observations will provide longer time baselines for searches
similar to ours and may in turn constrain the evolutionary scenarios of SMBH
binaries.


title: Spatial Dependence of Electron Interactions in Carbon Nanotubes

abstract:
  We report measurements of the spatial dependence of the electron energy
distribution in carbon nanotubes, from which electron interactions are
determined. Using nonequilibrium tunneling spectroscopy with multiple
superconducting probes, we characterize electron transport as ballistic or
diffusive, and interactions as elastic or inelastic. We find that transport in
nanotubes is generally diffusive, caused by elastic scattering from a few
defects. However, local inelastic scattering can be tuned `on' or `off' with a
gate voltage.


title:
Dynamical symmetry breaking with optimal control: reducing the number of
  pieces

abstract:
  We analyse the production of defects during the dynamical crossing of a
mean-field phase transition with a real order parameter. When the parameter
that brings the system across the critical point changes in time according to a
power-law schedule, we recover the predictions dictated by the well-known
Kibble-Zurek theory. For a fixed duration of the evolution, we show that the
average number of defects can be drastically reduced for a very large but
finite system, by optimising the time dependence of the driving using optimal
control techniques. Furthermore, the optimised protocol is robust against small
fluctuations.


title: Negativity and topological order in the toric code

abstract:
  In this manuscript we study the behaviour of the entanglement measure dubbed
negativity in the context of the toric code model. Using a method introduced
recently by Calabrese, Cardy and Tonni [Phys. Rev. Lett. 109, 130502 (2012)],
we obtain an exact expression which illustrates how the non-local correlations
present in a topologically ordered state reflect in the behaviour of the
negativity of the system. We find that the negativity has a leading area-law
contribution, if the subsystems are in direct contact with one another (as
expected in a zero-range correlated model). We also find a topological
contribution directly related to the topological entropy, provided that the
partitions are topologically non-trivial in both directions on a torus. We also
show that the negativity captures only quantum contributions to the
entanglement. Indeed, we show that the negativity vanishes identically for the
classical topologically ordered 8-vertex model, which on the contrary exhibits
a finite von Neumann entropy, inclusive of topological correction.


title:
Asymptotic optimality of a greedy randomized algorithm in a large-scale
  service system with general packing constraints

abstract:
  We consider a service system model primarily motivated by the problem of
efficient assignment of virtual machines to physical host machines in a network
cloud, so that the number of occupied hosts is minimized.
  There are multiple types of arriving customers, where a customer's mean
service time depends on its type. There is an infinite number of servers.
Multiple customers can be placed for service into one server, subject to
general "packing" constraints. Service times of different customers are
independent, even if served simultaneously by the same server. Each new
arriving customer is placed for service immediately, either into a server
already serving other customers (as long as packing constraints are not
violated) or into an idle server. After a service completion, each customer
leaves its server and the system.
  We propose an extremely simple and easily implementable customer placement
algorithm, called Greedy-Random (GRAND). It places each arriving customer
uniformly at random into either one of the already occupied servers (subject to
packing constraints) or one of the so-called zero-servers, which are empty
servers designated to be available to new arrivals. One instance of GRAND,
called GRAND($aZ$), where $a\ge 0$ is a parameter, is such that the number of
zero-servers at any given time $t$ is $aZ(t)$, where $Z(t)$ is the current
total number of customers in the system. We prove that GRAND($aZ$) with $a>0$
is asymptotically optimal, as the customer arrival rates grow to infinity and
$a\to 0$, in the sense of minimizing the total number of occupied servers in
steady state. In addition, we study by simulations various versions of GRAND
and observe the dependence of convergence speed and steady-state performance on
the number of zero-servers.


title:
Evidence of a nonequilibrium distribution of quasiparticles in the
  microwave response of a superconducting aluminium resonator

abstract:
  In a superconductor absorption of photons with an energy below the
superconducting gap leads to redistribution of quasiparticles over energy and
thus induces a strong non-equilibrium quasiparticle energy distribution. We
have measured the electrodynamic response, quality factor and resonant
frequency, of a superconducting aluminium microwave resonator as a function of
microwave power and temperature. Below 200 mK, both the quality factor and
resonant frequency decrease with increasing microwave power, consistent with
the creation of excess quasiparticles due to microwave absorption.
Counterintuitively, above 200 mK, the quality factor and resonant frequency
increase with increasing power. We demonstrate that the effect can only be
understood by a non-thermal quasiparticle distribution.


title: Theta-point polymers in the plane and Schramm-Loewner evolution

abstract:
  We study the connection between polymers at the theta temperature on the
lattice and Schramm-Loewner chains with constant step length in the continuum.
The latter realize a useful algorithm for the exact sampling of tricritical
polymers, where finite-chain effects are excluded. The driving function
computed from the lattice model via a radial implementation of the zipper
method is shown to converge to Brownian motion of diffusivity kappa=6 for large
times. The distribution function of an internal portion of walk is well
approximated by that obtained from Schramm-Loewner chains. The exponent of the
correlation length nu and the leading correction-to scaling exponent Delta_1
measured in the continuum are compatible with nu=4/7 (predicted for the theta
point) and Delta_1=72/91 (predicted for percolation). Finally, we compute the
shape factor and the asphericity of the chains, finding surprising accord with
the theta-point end-to-end values.


title:
Additive versus multiplicative parameters - applications in economics
  and finance

abstract:
  In this paper, we pay our attention to geometric parameters and their
applications in economics and finance. We discuss the multiplicative models in
which a geometric mean and a geometric standard deviation are more natural than
arithmetic ones. We give two examples from Warsaw Stock Exchange in 1995--2009
and from a bid of 52-week treasury bills in 1992--2009 in Poland as an
illustrative example. For distributions having applications in finance and
insurance we give their multiplicative parameters as well as their estimations.
We consider, among others, heavy-tailed distributions such as lognormal and
Pareto distribution, applied to modelling of large losses.


title: Dust time in quantum cosmology

abstract:
  We give a formulation of quantum cosmology with a pressureless dust and
arbitrary additional matter fields. The dust provides a natural time gauge
corresponding to a cosmic time, yielding a physical time independent
Hamiltonian. The approach simplifies the analysis of both Wheeler-deWitt and
loop quantum cosmology models, broadening the applicability of the latter.


title: Critical Line of the O($N$) Loop Model on the Square Lattice

abstract:
  An efficient algorithm is presented to simulate the O(N) loop model on the
square lattice for arbitrary values of $N>0$. The scheme combines the worm
algorithm with a new data structure to resolve both the problem of loop
crossings and the necessity of counting the number of loops at each Monte Carlo
update. With the use of this scheme, the line of critical points (and other
properties) of the O($N$) model on the square lattice for $0<N\le 2$ have been
determined.


title:
Harvesting Resource Allocation in Energy Harvesting Wireless Sensor
  Networks

abstract:
  Considering an energy harvesting sensor network, the overall probability of
event loss is derived. Based on this result, a variety of harvesting resource
allocation schemes (sizing the energy storages and the harvesting devices,
under a total cost constraint) are provided. Their performances are verified
and compared through simulations.


title: Review of the anisotropy working group at UHECR-2012

abstract:
  The study of ultra-high energy cosmic rays (UHECRs) has recently experienced
a jump in statistics as well as improved instrumentation. This has allowed a
better sensitivity in searching for anisotropies in the arrival directions of
cosmic rays. In this written version of the presentation given by the
inter-collaborative "Anisotropy Working Group" at the International Symposium
on Future Directions in UHECR physics at CERN in February 2012, we report on
the current status for anisotropy searches in the arrival directions of UHECRs.


title:
Safeguarding E-Commerce against Advisor Cheating Behaviors: Towards More
  Robust Trust Models for Handling Unfair Ratings

abstract:
  In electronic marketplaces, after each transaction buyers will rate the
products provided by the sellers. To decide the most trustworthy sellers to
transact with, buyers rely on trust models to leverage these ratings to
evaluate the reputation of sellers. Although the high effectiveness of
different trust models for handling unfair ratings have been claimed by their
designers, recently it is argued that these models are vulnerable to more
intelligent attacks, and there is an urgent demand that the robustness of the
existing trust models has to be evaluated in a more comprehensive way. In this
work, we classify the existing trust models into two broad categories and
propose an extendable e-marketplace testbed to evaluate their robustness
against different unfair rating attacks comprehensively. On top of highlighting
the robustness of the existing trust models for handling unfair ratings is far
from what they were claimed to be, we further propose and validate a novel
combination mechanism for the existing trust models, Discount-then-Filter, to
notably enhance their robustness against the investigated attacks.


title:
Statistical Properties of Exciton Fine Structure Splittings and
  Polarization Angles in Quantum Dot Ensembles

abstract:
  We propose an effective model to describe the statistical properties of
exciton fine structure splitting (FSS) and polarization angle of quantum dot
ensembles (QDEs). We derive the distributions of FSS and polarization angle for
QDEs and show that their statistical features can be fully characterized using
at most three independent measurable parameters. The effective model is
confirmed using atomistic pseudopotential calculations as well as experimental
measurements for several rather different QDEs. The model naturally addresses
three fundamental questions that are frequently encountered in theories and
experiments: (I) Why the probability of finding QDs with vanishing FSS is
generally very small? (II) Why FSS and polarization angle differ dramatically
from QD to QD? and (III) Is there any direct connection between FSS, optical
polarization and the morphology of QDs? The answers to these fundamental
questions yield a completely new physical picture for understanding optical
properties of QDEs.


title: Active current sheets and hot flow anomalies in Mercury's bow shock

abstract:
  Hot flow anomalies (HFAs) represent a subset of solar wind discontinuities
interacting with collisionless bow shocks. They are typically formed when the
normal component of motional (convective) electric field points toward the
embedded current sheet on at least one of its sides. The core region of an HFA
contains hot and highly deflected ion flows and rather low and turbulent
magnetic field. In this paper, we report first observations of HFA-like events
at Mercury identified over a course of two planetary years. Using data from the
orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and
Ranging (MESSENGER) mission, we identify a representative ensemble of active
current sheets magnetically connected to Mercury's bow shock. We show that some
of these events exhibit unambiguous magnetic and particle signatures of HFAs
similar to those observed earlier at other planets, and present their key
physical characteristics. Our analysis suggests that Mercury's bow shock does
not only mediate the flow of supersonic solar wind plasma but also provides
conditions for local particle acceleration and heating as predicted by previous
numerical simulations. Together with earlier observations of HFA activity at
Earth, Venus and Saturn, our results confirm that hot flow anomalies are a
common property of planetary bow shocks, and show that the characteristic size
of these events is of the order of one planetary radius.


title: A fixed-point approximation for a routing model in equilibrium

abstract:
  We use a method of Luczak (arXiv:1212.3231) to investigate the equilibrium
distribution of a dynamic routing model on a network. In this model, there are
$n$ nodes, each pair joined by a link of capacity $C$. For each pair of nodes,
calls arrive for this pair of endpoints as a Poisson process with rate
$\lambda$. A call for endpoints $\{u,v\}$ is routed directly onto the link
between the two nodes if there is spare capacity; otherwise $d$ two-link paths
between $u$ and $v$ are considered, and the call is routed along a path with
lowest maximum load, if possible. The duration of each call is an exponential
random variable with unit mean. In the case $d=1$, it was suggested by Gibbens,
Hunt and Kelly in 1990 that the equilibrium of this process is related to the
fixed points of a certain equation. We show that this is indeed the case, for
every $d \ge 1$, provided the arrival rate $\lambda$ is either sufficiently
small or sufficiently large. In either regime, we show that the equation has a
unique fixed point, and that, in equilibrium, for each $j$, the proportion of
links at each node with load $j$ is strongly concentrated around the $j$th
coordinate of the fixed point.


title: A Local Computation Approximation Scheme to Maximum Matching

abstract:
  We present a polylogarithmic local computation matching algorithm which
guarantees a $(1-\eps)$-approximation to the maximum matching in graphs of
bounded degree.


title: Statistical mechanics of the US Supreme Court

abstract:
  We build simple models for the distribution of voting patterns in a group,
using the Supreme Court of the United States as an example. The least
structured, or maximum entropy, model that is consistent with the observed
pairwise correlations among justices' votes is equivalent to an Ising spin
glass. While all correlations (perhaps surprisingly) are positive, the
effective pairwise interactions in the spin glass model have both signs,
recovering some of our intuition that justices on opposite sides of the
ideological spectrum should have a negative influence on one another. Despite
the competing interactions, a strong tendency toward unanimity emerges from the
model, and this agrees quantitatively with the data. The model shows that
voting patterns are organized in a relatively simple "energy landscape,"
correctly predicts the extent to which each justice is correlated with the
majority, and gives us a measure of the influence that justices exert on one
another. These results suggest that simple models, grounded in statistical
physics, can capture essential features of collective decision making
quantitatively, even in a complex political context.


title:
Signal Transmission Across Tile Assemblies: 3D Static Tiles Simulate
  Active Self-Assembly by 2D Signal-Passing Tiles

abstract:
  The 2-Handed Assembly Model (2HAM) is a tile-based self-assembly model in
which, typically beginning from single tiles, arbitrarily large aggregations of
static tiles combine in pairs to form structures. The Signal-passing Tile
Assembly Model (STAM) is an extension of the 2HAM in which the tiles are
dynamically changing components which are able to alter their binding domains
as they bind together. For our first result, we demonstrate useful techniques
and transformations for converting an arbitrarily complex STAM$^+$ tile set
into an STAM$^+$ tile set where every tile has a constant, low amount of
complexity, in terms of the number and types of ``signals'' they can send, with
a trade off in scale factor.
  Using these simplifications, we prove that for each temperature $\tau>1$
there exists a 3D tile set in the 2HAM which is intrinsically universal for the
class of all 2D STAM$^+$ systems at temperature $\tau$ (where the STAM$^+$ does
not make use of the STAM's power of glue deactivation and assembly breaking, as
the tile components of the 2HAM are static and unable to change or break
bonds). This means that there is a single tile set $U$ in the 3D 2HAM which
can, for an arbitrarily complex STAM$^+$ system $S$, be configured with a
single input configuration which causes $U$ to exactly simulate $S$ at a scale
factor dependent upon $S$. Furthermore, this simulation uses only two planes of
the third dimension. This implies that there exists a 3D tile set at
temperature $2$ in the 2HAM which is intrinsically universal for the class of
all 2D STAM$^+$ systems at temperature $1$. Moreover, we show that for each
temperature $\tau>1$ there exists an STAM$^+$ tile set which is intrinsically
universal for the class of all 2D STAM$^+$ systems at temperature $\tau$,
including the case where $\tau = 1$.


title: Improving the autodependogram using the Kulback-Leibler divergence

abstract:
  The autodependogram is a graphical device recently proposed in the literature
to analyze autodependencies. It is defined computing the classical Pearson
chi-square statistics of independence at various lags in order to point out the
presence lag-depedencies. This paper proposes an improvement of this diagram
obtained by substituting the chi-square statistics with an estimator of the
Kulback-Leibler divergence between the bivariate density of two delayed
variables and the product of their marginal distributions. A simulation study,
on well-established time series models, shows that this new autodependogram is
more powerful than the previous one. An application to financial data is also
shown.


title: Infinite Symmetric Matrices over Z_2 and the Lights Out Problem

abstract:
  We show, using a hybrid analysis/linear algebra argument, that the diagonal
vector of an infinite symmetric matrix over ${\mathbb Z}_2$ is contained in the
range of the matrix. We apply this result to an extension, to the countable
infinite case, of the Lights Out problem.


title: Likelihood Orders for some Random Walks on the Symmetric Group

abstract:
  Several cycle lexicographical orders are found to describe the relative
likelihood of elements of the random walks on the symmetric group generated by
the conjugacy classes of transpositions, 3-cycles, and n-cycles. Spectral
analysis finds sufficient time for the orders to hold. This partially answers a
conjecture that the n-cycles are the least likely elements of the transposition
walk on the symmetric group. A likelihood order contributes to understanding
the total variation distance and separation distance for a random walk.


title: Project X: Physics Opportunities

abstract:
  Part 2 of "Project X: Accelerator Reference Design, Physics Opportunities,
Broader Impacts". In this Part, we outline the particle-physics program that
can be achieved with Project X, a staged superconducting linac for
intensity-frontier particle physics. Topics include neutrino physics, kaon
physics, muon physics, electric dipole moments, neutron-antineutron
oscillations, new light particles, hadron structure, hadron spectroscopy, and
lattice-QCD calculations. Part 1 is available as arXiv:1306.5022
[physics.acc-ph] and Part 3 is available as arXiv:1306.5024 [physics.acc-ph].

categories: hep-ex hep-lat hep-ph nucl-ex nucl-th physics.acc-ph


title:
The Location of Oort Cloud Comets C/2011 L4 Panstarrs and C/2012 S1
  ISON, on a Comets' Evolutionary Diagram

abstract:
  We plot the Secular Light Curves (SLCs) of comets C/2011 L4 Panstarrs and
C/2012 S1 ISON. The brightness of C/2011 L4 Panstarrs and C/2012 S1 ISON
increase steeply after discovery but both decrease in slope sharply at ~4-5 AU,
a characteristic of Oort Cloud cometary light curves that we refer to as a
Slope Discontinuity Event (SDE). After the SDE, the SLC of C/2011 L4 continues
to increase and has a surge near perihelion. The SLC of comet C/2012 S1 ISON on
the other hand, is very odd and exhibits a SDE plus a near-standstill after the
event. We found five comets with similar behavior: C/1996 Q1 Tabur, C/1999 S4
LINEAR, C/2002 O4 H\"onig, C/2010 X1 Elenin and C/2012 T5 Bressi, all of which
disintegrated. Thus we predict that comet ISON will disintegrate too. We
compiled published production rates of water, dust and CO and used them to
calculate the Mass Loss Budget. We use this information for ISON to calculate
the diameter and to plot 29 comets in an Evolutionary Diagram that separates
comets by class. We find a diameter D = 1030+-70 m in excellent agreement with
the upper limit found by Delamere et al. (2013), D(mean) < 1126 m. It is
evident that the Secular Light Curves, exhibit complexity beyond current
scientific understanding. Note: The comet disintegrated as predicted (CBET
3731), while this paper was being refereed.


title:
A high throughput (>90%), large compensation range, single-prism
  femtosecond pulse compressor

abstract:
  We demonstrate a high throughput, large compensation range, single-prism
femtosecond pulse compressor, using a single prism and two roof mirrors. The
compressor has zero angular dispersion, zero spatial dispersion, zero
pulse-front tilt, and unity magnification. The high efficiency is achieved by
adopting two roof mirrors as the retroreflectors. We experimentally achieved ~
-14500 fs2 group delay dispersion (GDD) with 30 cm of prism tip-roof mirror
prism separation, and ~90.7% system throughput with the current implementation.
With better components, the throughput can be even higher.


title: Experimental test of the spin mixing interface conductivity concept

abstract:
  We perform a quantitative, comparative study of the spin pumping, spin
Seebeck and spin Hall magnetoresistance effects, all detected via the inverse
spin Hall effect in a series of over 20 yttrium iron garnet/Pt samples. Our
experimental results fully support present, exclusively spin current-based,
theoretical models using a single set of plausible parameters for spin mixing
conductance, spin Hall angle and spin diffusion length. Our findings establish
the purely spintronic nature of the aforementioned effects and provide a
quantitative description in particular of the spin Seebeck effect.


title: Randomized Interpolative Decomposition of Separated Representations

abstract:
  We introduce tensor Interpolative Decomposition (tensor ID) for the reduction
of the separation rank of Canonical Tensor Decompositions (CTDs). Tensor ID
selects, for a user-defined accuracy \epsilon, a near optimal subset of terms
of a CTD to represent the remaining terms via a linear combination of the
selected terms. Tensor ID can be used as an alternative to or a step of the
Alternating Least Squares (ALS) algorithm. In addition, we briefly discuss
Q-factorization to reduce the size of components within an ALS iteration.
Combined, tensor ID and Q-factorization lead to a new paradigm for the
reduction of the separation rank of CTDs. In this context, we also discuss the
spectral norm as a computational alternative to the Frobenius norm.
  We reduce the problem of finding tensor IDs to that of constructing
Interpolative Decompositions of certain matrices. These matrices are generated
via either randomized projection or randomized sampling of the given tensor. We
provide cost estimates and several examples of the new approach to the
reduction of separation rank.


title: Convergence Time Towards Periodic Orbits in Discrete Dynamical Systems

abstract:
  We investigate the convergence towards periodic orbits in discrete dynamical
systems. We examine the probability that a randomly chosen point converges to a
particular neighborhood of a periodic orbit in a fixed number of iterations,
and we use linearized equations to examine the evolution near that
neighborhood. The underlying idea is that points of stable periodic orbit are
associated with intervals. We state and prove a theorem that details what
regions of phase space are mapped into these intervals (once they are known)
and how many iterations are required to get there. We also construct algorithms
that allow our theoretical results to be implemented successfully in practice.


title: Heat kernels and analyticity of non-symmetric jump diffusion semigroups

abstract:
  Let $d\geq 1$ and $\alpha \in (0, 2)$. Consider the following non-local and
non-symmetric L\'evy-type operator on $\mR^d$: $$
\sL^\kappa_{\alpha}f(x):=\mbox{p.v.}\int_{\mR^d}(f(x+z)-f(x))\frac{\kappa(x,z)}{|z|^{d+\alpha}}
\dif z, $$ where $0<\kappa_0\leq \kappa(x,z)\leq \kappa_1$,
$\kappa(x,z)=\kappa(x,-z)$, and
$|\kappa(x,z)-\kappa(y,z)|\leq\kappa_2|x-y|^\beta$ for some $\beta\in(0,1)$.
Using Levi's method, we construct the fundamental solution (also called heat
kernel) $p^\kappa_\alpha (t, x, y)$ of $\sL^\kappa_\alpha $, and establish its
sharp two-sided estimates as well as its fractional derivative and gradient
estimates of the heat kernel. We also show that $p^\kappa_\alpha (t, x, y)$ is
jointly H\"older continuous in $(t, x)$. The lower bound heat kernel estimate
is obtained by using a probabilistic argument. The fundamental solution of
$\sL^\kappa_{\alpha}$ gives rise a Feller process $\{X, \mP_x, x\in \mR^d\}$ on
$\mR^d$. We determine the L\'evy system of $X$ and show that $\mP_x$ solves the
martingale problem for $(\sL^\kappa_{\alpha}, C^2_b(\mR^d))$. Furthermore, we
obtain the analyticity of the non-symmetric semigroup associated with
$\sL^\kappa_\alpha $ in $L^p$-spaces for every $p\in[1,\infty)$. A maximum
principle for solutions of the parabolic equation $\partial_t u
=\sL^\kappa_\alpha u$ is also established.


title: Nonlocal Hormander's hypoellipticity theorem

abstract:
  Consider the following nonlocal integro-differential operator: for
$\alpha\in(0,2)$, $$ \cal L^{(\alpha)}_{\sigma,b} f(x):=\mbox{p.v.}
\int_{\mathbb{R}^d-\{0\}}\frac{f(x+\sigma(x)z)-f(x)}{|z|^{d+\alpha}}d
z+b(x)\cdot\nabla f(x), $$ where
$\sigma:\mathbb{R}^d\to\mathbb{R}^d\times\mathbb{R}^d$ and
$b:\mathbb{R}^d\to\mathbb{R}^d$ are two $C^\infty_b$-functions, and p.v. stands
for the Cauchy principal value. Let $B_1(x):=\sigma(x)$ and
$B_{j+1}(x):=b(x)\cdot\nabla B_j(x)-\nabla b(x)\cdot B_j(x)$ for
$j\in\mathbb{N}$. Under the following H\"ormander's type condition: for any
$x\in\mathbb{R}^d$ and some $n=n(x)\in\mathbb{N}$, $$ \mathrm{Rank}[B_1(x),
B_2(x),\cdots, B_n(x)]=d, $$ by using the Malliavin calculus, we prove the
existence of the heat kernel $\rho_t(x,y)$ to the operator $\cal
L^{(\alpha)}_{\sigma,b}$ as well as the continuity of $x\mapsto
\rho_t(x,\cdot)$ in $L^1(\mathbb{R}^d)$ for each $t>0$. Moreover, when
$\sigma(x)=\sigma$ is constant, under the following uniform H\"ormander's type
condition: for some $j_0\in\mathbb{N}$, $$
\inf_{x\in\mathbb{R}^d}\inf_{|u|=1}\sum_{j=1}^{j_0}|u B_j(x)|^2>0, $$ we also
prove the smoothness of $(t,x,y)\mapsto\rho_t(x,y)$ with
$\rho_t(\cdot,\cdot)\in C^\infty_b(\mathbb{R}^d\times\mathbb{R}^d)$ for each
$t>0$.


title:
Fisher-Hartwig expansion for Toeplitz determinants and the spectrum of a
  single-particle reduced density matrix for one-dimensional free fermions

abstract:
  We study the spectrum of the Toeplitz matrix with a sine kernel, which
corresponds to the single-particle reduced density matrix for free fermions on
the one-dimensional lattice. For the spectral determinant of this matrix, a
Fisher--Hartwig expansion in the inverse matrix size has been recently
conjectured. This expansion can be verified order by order, away from the line
of accumulation of zeros, using the recurrence relation known from the theory
of discrete Painleve equations. We perform such a verification to the tenth
order and calculate the corresponding coefficients in the Fisher-Hartwig
expansion. Under the assumption of the validity of the Fisher-Hartwig expansion
in the whole range of the spectral parameter, we further derive expansions for
an equation on the eigenvalues of this matrix and for the von Neumann
entanglement entropy in the corresponding fermion problem. These analytical
results are supported by a numerical example.

categories: cond-mat.mes-hall cond-mat.stat-mech math-ph math.MP quant-ph


title: Information embedding and the triple role of control

abstract:
  We consider the problem of information embedding where the encoder modifies a
white Gaussian host signal in a power-constrained manner to encode a message,
and the decoder recovers both the embedded message and the modified host
signal. This partially extends the recent work of Sumszyk and Steinberg to the
continuous-alphabet Gaussian setting. Through a control-theoretic lens, we
observe that the problem is a minimalist example of what is called the "triple
role" of control actions. We show that a dirty-paper-coding strategy achieves
the optimal rate for perfect recovery of the modified host and the message for
any message rate. For imperfect recovery of the modified host, by deriving
bounds on the minimum mean-square error (MMSE) in recovering the modified host
signal, we show that DPC-based strategies are guaranteed to attain within a
uniform constant factor of 16 of the optimal weighted sum of power required in
host signal modification and the MMSE in the modified host signal
reconstruction for all weights and all message rates. When specialized to the
zero-rate case, our results provide the tightest known lower bounds on the
asymptotic costs for the vector version of a famous open problem in
decentralized control: the Witsenhausen counterexample. Numerically, this
tighter bound helps us characterize the asymptotically optimal costs for the
vector Witsenhausen problem to within a factor of 1.3 for all problem
parameters, improving on the earlier best known bound of 2.


title:
Open Gromov-Witten disk invariants in the presence of an anti-symplectic
  involution

abstract:
  For a symplectic manifold with an anti-symplectic involution having non-empty
fixed locus, we construct a model of the moduli space of real sphere maps out
of moduli spaces of decorated disk maps and give an explicit expression for its
first Stiefel-Whitney class. As a corollary, we obtain a large number of
examples, which include all odd-dimensional projective spaces and many complete
intersections, for which many types of real moduli spaces are orientable. For
these manifolds, we define open Gromov-Witten invariants with no restriction on
the dimension of the manifolds or the type of the constraints if there are no
boundary marked points. If there are boundary marked points, we define the
invariants under some restrictions on the allowed boundary constraints, even
though the moduli spaces are not orientable in these cases.


title: Robustness of Quantum Criticality of Valence Fluctuations

abstract:
  The mechanism of emergence of robust quantum criticality in Yb- and Ce-based
heavy electron systems under pressure is analyzed theoretically. By
constructing a minimal model for quasicrystal Yb15Al34Au51 and its approximant,
we show that quantum critical points of the first-order valence transition of
Yb appear in the ground-state phase diagram with their critical regimes being
overlapped to be unified, giving rise to a wide quantum critical regime. This
well explains the robust unconventional criticality observed in Yb15Al34Au51
under pressure. We also discuss broader applicability of this mechanism to
other Yb- and Ce-based systems such as beta-YbAlB4 showing unconventional
quantum criticality.


title: Pinning down the cosmic ray source mechanism with new IceCube data

abstract:
  Very recently the IceCube Collaboration has reported an observation of 28
neutrino candidates with energies between 50 TeV and 2 PeV, constituting a
4.1$\sigma$ excess compared to the atmospheric background. In this article we
investigate the compatibility between the data and a hypothesized unbroken
power-law neutrino spectrum for various values of spectral index \Gamma >= 2.
We show that \Gamma ~ 2.3 is consistent at the ~ 1.5$\sigma$ level with the
observed events up to 2 PeV and to the null observation of events at higher
energies. We then assume that the sources of this unbroken spectrum are
Galactic, and deduce (i) an energy-transfer fraction from parent protons to
pions, and (ii) a way of discriminating among models which have been put forth
to explain the "knee" and "ankle" features of the cosmic ray spectrum. Future
IceCube data will test the unbroken power law hypothesis and provide a
multi-messenger approach to explaining features of the cosmic ray spectrum,
including the transition from Galactic to extragalactic dominance.


title: Project X: Accelerator Reference Design

abstract:
  Part 1 of "Project X: Accelerator Reference Design, Physics Opportunities,
Broader Impacts". Part 1 contains the volume Preface and a description of the
conceptual design for a high-intensity proton accelerator facility being
developed to support a world-leading program of Intensity Frontier physics over
the next two decades at Fermilab. Subjects covered include performance goals,
the accelerator physics design, and the technological basis for such a
facility. Part 2 is available as arXiv:1306.5009 [hep-ex] and Part 3 is
available as arXiv:1306.5024 [physics.acc-ph].


title: Numerical Simulation of Cosmic String Motion in Peres Background

abstract:
  The dynamics of closed cosmic strings in Peres background, using
finite-difference method, has been considered. It is shown that motion of the
strings is very complicated and its perform complex oscillations and deformed
to form loops and cusps.