title:
A Closer Earth and the Faint Young Sun Paradox: Modification of the Laws
  of Gravitation, or Sun/Earth Mass Losses?

abstract:
  Given a solar luminosity L_Ar = 0.75 L_0 at the beginning of the Archean 3.8
Gyr ago, where L_0 is the present-day one, if the heliocentric distance r of
the Earth was r_Ar = 0.956 r_0, the solar irradiance would have been as large
as I_Ar = 0.82 I_0. It would allowed for a liquid ocean on the terrestrial
surface which, otherwise, would have been frozen, contrary to the empirical
evidence. By further assuming that some physical mechanism subsequently
displaced the Earth towards its current distance in such a way that the
irradiance stayed substantially constant over the entire Archean from 3.8 Gyr
to 2.5 Gyr ago, a relative recession rate as large as \dot r/r \simeq 3.4 x
10^-11 yr^-1 would have been required. Although such a figure is roughly of the
same order of magnitude of the value of the Hubble parameter 3.8 Gyr ago H_Ar =
1.192 H_0 = 8.2 x 10^-11 yr^-1, standard general relativity rules out
cosmological explanations for the hypothesized Earth' s recession rate.
Instead, a class of modified theories of gravitation with nonminimal coupling
between the matter and the metric naturally predicts a secular variation of the
relative distance of a localized two-body system, thus yielding a potentially
viable candidate to explain the putative recession of the Earth' s orbit.
Another competing mechanism of classical origin which could, in principle,
allow for the desired effect is the mass loss which either the Sun or the Earth
itself may have experienced during the Archean. On the one hand, this implies
that our planet should have lost 2% of its present mass in the form of
eroded/evaporated hydrosphere which, thus, should have been two orders of
magnitude larger than now. On the other hand, it is widely believed that the
Sun could have lost mass at an enhanced rate due to a stronger solar wind in
the past for not more than \sim 0.2-0.3 Gyr.


title: Anomalous Heat Diffusion

abstract:
  Consider anomalous energy spread in solid phases, i.e., $MSD= \int (x -{< x
>}_E)^2 \rho_E(x,t)dx \propto t^{\beta}$, as induced by a small initial excess
energy perturbation distribution $\rho_{E}(x,t=0)$ away from equilibrium. The
associated total thermal equilibrium heat flux autocorrelation function
$C_{JJ}(t)$ is shown to obey rigorously the intriguing relation, $d^2 MSD/dt^2
= 2C_{JJ}(t)/(k_BT^2c)$, where $c$ is the specific volumetric heat capacity.
Its integral assumes a time-local Helfand-moment relation; i.e. $
dMSD/dt|_{t=t_s} = 2/(k_BT^2c)\int_0^{t_s} C_{JJ}(s)ds$, where the chosen
cut-off time $t_s$ is determined by the maximal signal velocity for heat
transfer. Given the premise that the averaged nonequilibrium heat flux is
governed by an anomalous heat conductivity, energy diffusion scaling
necessarily determines a corresponding anomalous thermal conductivity scaling
behavior.


title:
Non-Gaussian entangled states and quantum teleportation of
  Schr\"odinger-cat states

abstract:
  In continuous-variable quantum information, non-Gaussian entangled states
that are obtained from Gaussian entangled states via photon subtraction are
known to contain more entanglement. This makes them better resources for
quantum information processing protocols, such as, quantum teleportation. We
discuss the teleportation of non-Gaussian, non-classical Schr\"odinger-cat
states of light using two-mode squeezed vacuum light that is made non-Gaussian
via subtraction of a photon from each of the two modes. We consider the
experimentally realizable cat states produced by subtracting a photon from the
single-mode squeezed vacuum state. We discuss two figures of merit for the
teleportation process, a) the fidelity, and b) the maximum negativity of the
Wigner function at the output. We elucidate how the non-Gaussian entangled
resource lowers the requirements on the amount of squeezing necessary to
achieve any given fidelity of teleportation, or to achieve negative values of
the Wigner function at the output.


title:
Coherent Backscattering in Fock Space: a Signature of Quantum Many-Body
  Interference in Interacting Bosonic Systems

abstract:
  We predict a generic manifestation of quantum interference in many-body
bosonic systems resulting in a coherent enhancement of the average return
probability in Fock space. This enhancement is both robust with respect to
variations of external parameters and genuinely quantum insofar as it cannot be
described within mean-field approaches. As a direct manifestation of the
superposition principle in Fock space, it arises when many-body equilibration
due to interactions sets in. Using a semiclassical approach based on
interfering paths in Fock space, we calculate the magnitude of the
backscattering peak and its dependence on gauge fields that break time-reversal
invariance. We confirm our predictions by comparing them to exact quantum
evolution probabilities in Bose-Hubbard models, and discuss the relevance of
our findings in the context of many-body thermalization.


title: Large flats in the pants graph

abstract:
  This note is about the geometry of the pants graph P(S), a natural simplicial
graph associated to a finite type topological surface S where vertices
represents pants decompositions. The main result in this note ascserts that for
a multicurve Q whose complement is a number of subsurfaces of complexity at
most 1. We prove that the corresponding subgraph P(Q) is totally geodesic in P,
previously considering this as a metric space assigning length one to each
edge. A flat is a graph isomorphic to the Cayley graph of an abelian torsion
free group of finite rank. As a consequence of the main theorem we make
explicit the existence of maximal size flats (large flats) in the pants graph.


title:
Confidence Intervals and Hypothesis Testing for High-Dimensional
  Regression

abstract:
  Fitting high-dimensional statistical models often requires the use of
non-linear parameter estimation procedures. As a consequence, it is generally
impossible to obtain an exact characterization of the probability distribution
of the parameter estimates. This in turn implies that it is extremely
challenging to quantify the \emph{uncertainty} associated with a certain
parameter estimate. Concretely, no commonly accepted procedure exists for
computing classical measures of uncertainty and statistical significance as
confidence intervals or $p$-values for these models.
  We consider here high-dimensional linear regression problem, and propose an
efficient algorithm for constructing confidence intervals and $p$-values. The
resulting confidence intervals have nearly optimal size. When testing for the
null hypothesis that a certain parameter is vanishing, our method has nearly
optimal power.
  Our approach is based on constructing a `de-biased' version of regularized
M-estimators. The new construction improves over recent work in the field in
that it does not assume a special structure on the design matrix. We test our
method on synthetic data and a high-throughput genomic data set about
riboflavin production rate.


title: Adapting sample size in particle filters through KLD-resampling

abstract:
  This letter provides an adaptive resampling method. It determines the number
of particles to resample so that the Kullback-Leibler distance (KLD) between
distribution of particles before resampling and after resampling does not
exceed a pre-specified error bound. The basis of the method is the same as
Fox's KLD-sampling but implemented differently. The KLD-sampling assumes that
samples are coming from the true posterior distribution and ignores any
mismatch between the true and the proposal distribution. In contrast, we
incorporate the KLD measure into the resampling in which the distribution of
interest is just the posterior distribution. That is to say, for sample size
adjustment, it is more theoretically rigorous and practically flexible to
measure the fit of the distribution represented by weighted particles based on
KLD during resampling than in sampling. Simulations of target tracking
demonstrate the efficiency of our method.


title:
Steepest-Entropy-Ascent and Maximal-Entropy-Production Dynamical Models
  of Irreversible Relaxation to Stable Equilibrium from Any Non-Equilibrium
  State. Unified Treatment for Six Non-Equilibrium Frameworks

abstract:
  By suitable reformulations, we review the mathematical frameworks of six
different approaches to the description of non-equilibrium dynamics with the
purpose to set up a unified formulation of the Maximum Entropy Production (MEP)
principle valid in all these contexts. In this way, we extend to such
frameworks the concept of Steepest Entropy Ascent dynamics introduced by the
present author in previous work on quantum thermodynamics. Actually, the
present formulation constitutes a generalization also in the quantum
thermodynamics framework. The analysis emphasizes that in the SEA-inspired
implementation of the MEP principle, a key role is played by the geometrical
metric with respect to which to measure the length of a trajectory in state
space. The metric tensor turns out to be directly related to the inverse of the
Onsager's generalized conductivity tensor. We conclude that in most of the
existing theories of non-equilibrium the time evolution of the state
representative can be seen to actually follow in state space the path of SEA
with respect to a suitable metric connected with the generalized
conductivities. The resulting unified family of SAE/MEP dynamical models are
all intrinsically consistent with the second law of thermodynamics. The
nonnegativity of the entropy production is a general and readily proved feature
of SEA dynamics. In several of the different approaches to non-equilibrium
description we consider here, the SEA concept has not been investigated before.
Therefore, it is hoped that the present unifying approach may prove useful in
providing a fresh basis for effective, thermodynamically consistent, numerical
models and theoretical treatments of irreversible conservative relaxation
towards equilibrium from far non-equilibrium states.


title:
Distance to the scaling law: a useful approach for unveiling
  relationships between crime and urban metrics

abstract:
  We report on a quantitative analysis of relationships between the number of
homicides, population size and other ten urban metrics. By using data from
Brazilian cities, we show that well defined average scaling laws with the
population size emerge when investigating the relations between population and
number of homicides as well as population and urban metrics. We also show that
the fluctuations around the scaling laws are log-normally distributed, which
enabled us to model these scaling laws by a stochastic-like equation driven by
a multiplicative and log-normally distributed noise. Because of the scaling
laws, we argue that it is better to employ logarithms in order to describe the
number of homicides in function of the urban metrics via regression analysis.
In addition to the regression analysis, we propose an approach to correlate
crime and urban metrics via the evaluation of the distance between the actual
value of the number of homicides (as well as the value of the urban metrics)
and the value that is expected by the scaling law with the population size.
This approach have proved to be robust and useful for unveiling
relationships/behaviors that were not properly carried out by the regression
analysis, such as i) the non-explanatory potential of the elderly population
when the number of homicides is much above or much below the scaling law, ii)
the fact that unemployment has explanatory potential only when the number of
homicides is considerably larger than the expected by the power law, and iii) a
gender difference in number of homicides, where cities with female population
below the scaling law are characterized by a number of homicides above the
power law.


title: The Recycler Electron Cooler

abstract:
  The Recycler Electron cooler was the first (and so far, the only) cooler
working at a relativistic energy ({\gamma} = 9.5). It was successfully
developed in 1995-2004 and was in operation at Fermilab in 2005-2011, providing
cooling of antiprotons in the Recycler ring. This paper describes the cooler,
difficulties in achieving the required electron beam parameters and the ways to
overcome them, cooling measurements, and details of operation.


title: A theory of minimal K-types for flat G-bundles

abstract:
  The theory of minimal K-types for p-adic reductive groups was developed in
part to classify irreducible admissible representations with wild ramification.
An important observation was that minimal K-types associated to such
representations correspond to fundamental strata. These latter objects are
triples (x, r, beta), where x is a point in the Bruhat-Tits building of the
reductive group G, r is a nonnegative real number, and beta is a semistable
functional on the degree r associated graded piece of the Moy-Prasad filtration
corresponding to x.
  Recent work on the wild ramification case of the geometric Langlands
conjectures suggests that fundamental strata also play a role in the geometric
setting. In this paper, we develop a theory of minimal K-types for formal flat
G-bundles. We show that any formal flat G-bundle contains a fundamental
stratum; moreover, all such strata have the same rational depth. We thus obtain
a new invariant of a flat G-bundle called the slope, generalizing the classical
definition for flat connections. The slope can also be realized as the minimum
depth of a stratum contained in the flat G-bundle, and in the case of positive
slope, all such minimal depth strata are fundamental. Finally, we show that a
flat G-bundle is irregular singular if and only if it has positive slope.


title:
Enhancing Mobile Data Offloading with Mobility Prediction and
  Prefetching

abstract:
  We present procedures that exploit mobility prediction and prefetching to
enhance offloading of traffic from mobile networks to WiFi hotspots, for both
delay tolerant and delay sensitive traffic. We evaluate the procedures in terms
of the percentage of offloaded traffic, the data transfer delay, and the cache
size used for prefetching. The evaluation considers empirical measurements and
shows how various parameters influence the performance of the procedures, and
their robustness to time and throughput estimation errors.


title:
The Sobolev norms and localization on the Fourier side for the solutions
  to some evolution equations

abstract:
  Some evolution equations with rough time-dependent potential are studied in
the case of one-dimensional torus. We show that the solution has higher
regularity for the generic values of the coupling constant. The asymptotics for
large time and the localization on the Fourier side are studied.


title:
Classification of ground states and normal modes for phase-frustrated
  multicomponent superconductors

abstract:
  We classify ground states and normal modes for $n$-component superconductors
with frustrated intercomponent Josephson couplings, focusing on $n = 4$. The
results should be relevant not only to multiband superconductors, but also to
Josephson-coupled multilayers and Josephson-junction arrays. It was recently
discussed that three-component superconductors can break time-reversal symmetry
as a consequence of phase frustration. We discuss how to classify frustrated
superconductors with an arbitrary number of components. Although already for
the four-component case there are a large number of different combinations of
phase-locking and phase-antilocking Josephson couplings, we establish that
there are a much smaller number of equivalence classes where properties of
frustrated multicomponent superconductors can be mapped to each other. This
classification is related to the graph-theoretical concept of Seidel switching.
Numerically, we calculate ground states, normal modes, and characteristic
length scales for the four-component case. We report conditions of appearance
of new accidental continuous ground-state degeneracies.


title: STEREO/EUVI Event Catalog 2006-2012

abstract:
  We generated an event catalog with an automated detection algorithm based on
the entire EUVI image database observed with the two Solar Terrestrial
Relations Observatory STEREO-A and -B spacecraft over the first six years of
the mission (2006\,--\,2012). The event catalog includes the heliographic
positions of some 20\,000 EUV events, transformed from spacecraft coordinates
to Earth coordinates, and information on associated GOES flare events (down to
the level of GOES A5-class flares). The 304 \ang\ wavelength turns out to be
the most efficient channel for flare detection (79\,%), while the 171 \ang\
(4\,%), 195 \ang\ (10\,%), and the 284 \ang\ channel (7\,%) retrieve
substantially fewer flare events, partially due to the suppressing effect of
EUV dimming, and partially due to the lower cadence in the later years of the
mission. Due to the Sun-circling orbits of STEREO-A and -B, a large number of
flares have been detected on the farside of the Sun, invisible from Earth, or
seen as partially occulted events. The statistical size distributions of EUV
peak fluxes (with a power-law slope of $\alpha_P = 2.5\pm0.2$) and event
durations (with a power-law slope of $\alpha_T=2.4\pm0.3$) are found to be
consistent with the fractal-diffusive self-organized criticality model. The
EUVI event catalog is available on-line
\url{http://secchi.lmsal.com/EUVI/euvi__autodetection/euvi__events.txt} and may
serve as a comprehensive tool to identify stereoscopically observed flare
events for 3D reconstruction and to study occulted flare events.


title: An Efficient Branching Algorithm for Interval Completion

abstract:
  We study the \emph{{interval completion}} problem, which asks for the
insertion of a set of at most $k$ edges to make a graph of $n$ vertices into an
interval graph. We focus on chordal graphs with no small obstructions, where
every remaining obstruction is known to have a shallow property. From such a
shallow obstruction we single out a subset 6 or 7 vertices, called the frame,
and 5 missed edges in the subgraph induced by the frame. We show that if none
of these edges is inserted, then the frame cannot be altered at all, and the
whole obstruction is also fixed, by and large, in the sense that their related
positions in an interval representation of the objective interval graph have a
specific pattern. We propose a simple bounded search process, which effectively
transforms a given graph to a graph with the structural property that all
obstructions are shallow and have fixed frames. Then we fill in polynomial time
all obstructions that have been previously left in indecision. These efforts
together deliver a simple parameterized algorithm of time $6^k\cdot n^{O(1)}$
for the problem, significantly improving the only known parameterized algorithm
of time $k^{2k}\cdot n^{O(1)}$.


title: Generalized qubit portrait of the qutrit state density matrix

abstract:
  New inequalities for tomographic probability distributions and density
matrices of qutrit states are obtained by means of generalization of qubit
portrait method. The approach based on the qudit portrait method to get new
entropic inequalities is proposed. It can be applied to the case of arbutrary
nonnegative hermitian matrices including the density matrices of multipartite
qudit states.


title:
Optical Spin Noise of a Single Hole Spin Localized in an (InGa)As
  Quantum Dot

abstract:
  We advance spin noise spectroscopy to the ultimate limit of single spin
detection. This technique enables the measurement of the spin dynamic of a
single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and
light intensity dependent studies reveal even at low magnetic fields a strong
magnetic field dependence of the longitudinal heavy hole spin relaxation time
with an extremely long $T_1$ of $\ge$ 180 $\mu$s at 31 mT and 5 K. The
wavelength dependence of the spin noise power discloses for finite light
intensities an inhomogeneous single quantum dot spin noise spectrum which is
explained by charge fluctuations in the direct neighborhood of the quantum dot.
The charge fluctuations are corroborated by the distinct intensity dependence
of the effective spin relaxation rate.


title:
Scalar and vector Slepian functions, spherical signal estimation and
  spectral analysis

abstract:
  It is a well-known fact that mathematical functions that are timelimited (or
spacelimited) cannot be simultaneously bandlimited (in frequency). Yet the
finite precision of measurement and computation unavoidably bandlimits our
observation and modeling scientific data, and we often only have access to, or
are only interested in, a study area that is temporally or spatially bounded.
In the geosciences we may be interested in spectrally modeling a time series
defined only on a certain interval, or we may want to characterize a specific
geographical area observed using an effectively bandlimited measurement device.
It is clear that analyzing and representing scientific data of this kind will
be facilitated if a basis of functions can be found that are "spatiospectrally"
concentrated, i.e. "localized" in both domains at the same time. Here, we give
a theoretical overview of one particular approach to this "concentration"
problem, as originally proposed for time series by Slepian and coworkers, in
the 1960s. We show how this framework leads to practical algorithms and
statistically performant methods for the analysis of signals and their power
spectra in one and two dimensions, and, particularly for applications in the
geosciences, for scalar and vectorial signals defined on the surface of a unit
sphere.


title:
A semiparametric scale-mixture regression model and predictive recursion
  maximum likelihood

abstract:
  To avoid specification of the error distribution in a regression model, we
propose a general nonparametric scale mixture model for the error distribution.
For fitting such mixtures, the predictive recursion method is a simple and
computationally efficient alternative to existing methods. We define a
predictive recursion-based marginal likelihood function, and estimation of the
regression parameters proceeds by maximizing this function. A hybrid predictive
recursion--EM algorithm is proposed for this purpose. The method's performance
is compared with that of existing methods in simulations and real data
analyses.


title:
H.E.S.S and Fermi-LAT discovery of gamma rays from the blazar 1ES
  1312-423

abstract:
  A deep observation campaign carried out by the High Energy Stereoscopic
System (H.E.S.S.) on Centaurus A enabled the discovery of gamma rays from the
blazar 1ES 1312-423, two degrees away from the radio galaxy. With a
differential flux at 1 TeV of (1.9 +/-0.6(stat) +/-0.4(sys)) x 10^{-13} /cm^2
/s /TeV corresponding to 0.5% of the Crab nebula differential flux and a
spectral index of 2.9 +/- 0.5 (stat) +/- 0.2 (sys), 1ES 1312-423 is one of the
faintest sources ever detected in the very high energy (E>100 GeV)
extragalactic sky. A careful analysis using three and a half years of Fermi-LAT
data allows the discovery at high energies (E>100 MeV) of a hard spectrum
(index of 1.4 +/- 0.4 (stat) +/- 0.2 (sys)) source coincident with 1ES
1312-423. Radio, optical, UV and X-ray observations complete the spectral
energy distribution of this blazar, now covering 16 decades in energy. The
emission is successfully fitted with a synchrotron self Compton model for the
non-thermal component, combined with a black-body spectrum for the optical
emission from the host galaxy.


title: Convex bodies of states and maps

abstract:
  We give a general solution to the question when the convex hulls of orbits of
quantum states on a finite-dimensional Hilbert space under unitary actions of a
compact group have a non-empty interior in the surrounding space of all density
states. The same approach can be applied to study convex combinations of
quantum channels. The importance of both problems stems from the fact that,
usually, only sets with non-vanishing volumes in the embedding spaces of all
states or channels are of practical importance. For the group of local
transformations on a bipartite system we characterize maximally entangled
states by properties of a convex hull of orbits through them. We also compare
two partial characteristics of convex bodies in terms of largest balls and
maximum volume ellipsoids contained in them and show that, in general, they do
not coincide. Separable states, mixed-unitary channels and k-entangled states
are also considered as examples of our techniques.


title:
Phonon Dispersion and Elastic Moduli of Two-Dimensional Disordered
  Colloidal Packings of Soft Particles with Frictional Interactions

abstract:
  Particle tracking and displacement covariance matrix techniques are employed
to investigate the phonon dispersion relations of two-dimensional colloidal
glasses composed of soft, thermoresponsive microgel particles whose
temperature-sensitive size permits \textit{in situ} variation of particle
packing fraction. Bulk, $B$, and shear, $G$, moduli of the colloidal glasses
are extracted from the dispersion relations as a function of packing fraction,
and variation of the ratio $G/B$ with packing fraction is found to agree
quantitatively with predictions for jammed packings of frictional soft
particles. In addition, $G$ and $B$ individually agree with numerical
predictions for frictional particles. This remarkable level of agreement
enabled us to extract an energy scale for the inter-particle interaction from
the individual elastic constants and to derive an approximate estimate for the
inter-particle friction coefficient.


title:
The Compressibility in Strongly Correlated Superconductors and
  Superfluids: From BCS to BEC

abstract:
  We present a theoretical study of the compressibility, $\kappa$, in a Fermi
gas with attractive contact interactions, providing predictions for the
strongly-attractive regime and the superfluid phase. Our work emphasizes the
compressibility sum rule and gauge invariance as constraints on $\kappa$ and we
show how within a particular $t$-matrix approach, these can be satisfied in the
normal phase when no approximations are made. For tractability, approximations
must be introduced, and it is believed that thermodynamical approaches to
$\kappa$ are more reliable, than correlation function based schemes.
Contrasting with other studies in the literature, we present thermodynamic
calculations of $\kappa$; these yield semi-quantitative agreement with
experiment and provide physical insight into similar results obtained via
quantum Monte Carlo simulations.


title: A critical fractional equation with concave-convex power nonlinearities

abstract:
  In this work we study the following fractional critical problem $$
(P_{\lambda})=\left\{\begin{array}{ll} (-\Delta)^s u=\lambda u^{q} +
u^{2^*_{s}-1}, \quad u{>}0 & \mbox{in} \Omega\\ u=0 & \mbox{in} \RR^n\setminus
\Omega\,, \end{array}\right. $$ where $\Omega\subset \mathbb{R}^n$ is a regular
bounded domain, $\lambda>0$, $0<s<1$ and $n>2s$. Here $(-\Delta)^s$ denotes the
fractional Laplace operator defined, up to a normalization factor, by $$
-(-\Delta)^s u(x)={\rm P. V.}
\int_{\RR^n}\frac{u(x+y)+u(x-y)-2u(x)}{|y|^{n+2s}}\,dy, \quad x\in \RR^n. $$
Our main results show the existence and multiplicity of solutions to problem
$(P_\lambda)$ for different values of $\lambda$. The dependency on this
parameter changes according to whether we consider the concave power case
($0<q<1$) or the convex power case ($1<q<2^*_s-1$). These two cases will be
treated separately.


title:
Solving monotone inclusions involving parallel sums of linearly composed
  maximally monotone operators

abstract:
  The aim of this article is to present two different primal-dual methods for
solving structured monotone inclusions involving parallel sums of compositions
of maximally monotone operators with linear bounded operators. By employing
some elaborated splitting techniques, all of the operators occurring in the
problem formulation are processed individually via forward or backward steps.
The treatment of parallel sums of linearly composed maximally monotone
operators is motivated by applications in imaging which involve first- and
second-order total variation functionals, to which a special attention is
given.


title:
Energy flow and fluctuations in non-equilibrium conformal field theory
  on star graphs

abstract:
  We consider non-equilibrium quantum steady states in conformal field theory
(CFT) on star-graph configurations, with a particular, simple connection
condition at the vertex of the graph. These steady states occur after a large
time as a result of initially thermalizing the legs of the graph at different
temperatures, and carry energy flows. Using purely Virasoro algebraic
calculations we evaluate the exact long-time cumulant generating function for
these flows. We show that this function satisfies a generalization of the usual
non-equilibrium fluctuation relations. This extends the results by two of the
authors (J. Phys. A 45: 362001, 2012; arXiv:1302.3125) to the cases of more
than two legs. It also provides an alternative derivation centered on Virasoro
algebra operators rather than local fields, hence an alternative regularization
scheme, thus confirming the validity and universality of the long-time cumulant
generating function. Our derivation shows how the usual Virasoro algebra leads,
in large volumes, to a continuous-index Virasoro algebra for which we develop
diagramatic principles, which may be of interest in other non-equilibrium
contexts as well. Finally, our results shed light on the Poisson process
interpretation of the long-time energy transfer in CFT.


title:
Permutations avoiding 4321 and 3241 have an algebraic generating
  function

abstract:
  We show that permutations avoiding both of the (classical) patterns 4321 and
3241 have the algebraic generating function conjectured by Vladimir Kruchinin.


title: Unions of F-spaces

abstract:
  We show that every space that is the union of a `small' family consisting of
special P-sets that are F-spaces, is an F-space. We also comment on the
sharpness of our results.


title:
Partner Symmetries, Group Foliation and ASD Ricci-Flat Metrics without
  Killing Vectors

abstract:
  We demonstrate how a combination of our recently developed methods of partner
symmetries, symmetry reduction in group parameters and a new version of the
group foliation method can produce noninvariant solutions of complex
Monge-Amp\`ere equation (CMA) and provide a lift from invariant solutions of
CMA satisfying Boyer-Finley equation to non-invariant ones. Applying these
methods, we obtain a new noninvariant solution of CMA and the corresponding
Ricci-flat anti-self-dual Einstein-K\"ahler metric with Euclidean signature
without Killing vectors, together with Riemannian curvature two-forms. There
are no singularities of the metric and curvature in a bounded domain if we
avoid very special choices of arbitrary functions of a single variable in our
solution. This metric does not describe gravitational instantons because the
curvature is not concentrated in a bounded domain.


title: Wide-Gap Semiconducting Graphene from Nitrogen-Seeded SiC

abstract:
  All carbon electronics based on graphene has been an elusive goal. For more
than a decade, the inability to produce significant band-gaps in this material
has prevented the development of semiconducting graphene. While chemical
functionalization was thought to be a route to semiconducting graphene,
disorder in the chemical adsorbates, leading to low mobilities, have proved to
be a hurdle in its production. We demonstrate a new approach to produce
semiconducting graphene that uses a small concentration of covalently bonded
surface nitrogen, not as a means to functionalize graphene, but instead as a
way to constrain and bend graphene. We demonstrate that a submonolayer
concentration of nitrogen on SiC is sufficient to pin epitaxial graphene to the
SiC interface as it grows, causing the graphene to buckle. The resulting
3-dimensional modulation of the graphene opens a band-gap greater than 0.7eV in
the otherwise continuous metallic graphene sheet.


title:
Evolution method and "differential hierarchy" of colored knot
  polynomials

abstract:
  We consider braids with repeating patterns inside arbitrary knots which
provides a multi-parametric family of knots, depending on the "evolution"
parameter, which controls the number of repetitions. The dependence of knot
(super)polynomials on such evolution parameters is very easy to find. We apply
this evolution method to study of the families of knots and links which include
the cases with just two parallel and anti-parallel strands in the braid, like
the ordinary twist and 2-strand torus knots/links and counter-oriented 2-strand
links. When the answers were available before, they are immediately reproduced,
and an essentially new example is added of the "double braid", which is a
combination of parallel and anti-parallel 2-strand braids. This study helps us
to reveal with the full clarity and partly investigate a mysterious
hierarchical structure of the colored HOMFLY polynomials, at least, in
(anti)symmetric representations, which extends the original observation for the
figure-eight knot to many (presumably all) knots. We demonstrate that this
structure is typically respected by the t-deformation to the superpolynomials.


title: A Universal Machine for Biform Theory Graphs

abstract:
  Broadly speaking, there are two kinds of semantics-aware assistant systems
for mathematics: proof assistants express the semantic in logic and emphasize
deduction, and computer algebra systems express the semantics in programming
languages and emphasize computation. Combining the complementary strengths of
both approaches while mending their complementary weaknesses has been an
important goal of the mechanized mathematics community for some time. We pick
up on the idea of biform theories and interpret it in the MMTt/OMDoc framework
which introduced the foundations-as-theories approach, and can thus represent
both logics and programming languages as theories. This yields a formal,
modular framework of biform theory graphs which mixes specifications and
implementations sharing the module system and typing information. We present
automated knowledge management work flows that interface to existing
specification/programming tools and enable an OpenMath Machine, that
operationalizes biform theories, evaluating expressions by exhaustively
applying the implementations of the respective operators. We evaluate the new
biform framework by adding implementations to the OpenMath standard content
dictionaries.


title: The MMT API: A Generic MKM System

abstract:
  The MMT language has been developed as a scalable representation and
interchange language for formal mathematical knowledge. It permits natural
representations of the syntax and semantics of virtually all declarative
languages while making MMT-based MKM services easy to implement. It is
foundationally unconstrained and can be instantiated with specific formal
languages.
  The MMT API implements the MMT language along with multiple backends for
persistent storage and frontends for machine and user access. Moreover, it
implements a wide variety of MMT-based knowledge management services. The API
and all services are generic and can be applied to any language represented in
MMT. A plugin interface permits injecting syntactic and semantic idiosyncrasies
of individual formal languages.


title: Synthesis of unitaries with Clifford+T circuits

abstract:
  We describe a new method for approximating an arbitrary $n$ qubit unitary
with precision $\varepsilon$ using a Clifford and T circuit with
$O(4^{n}n(\log(1/\varepsilon)+n))$ gates. The method is based on rounding off a
unitary to a unitary over the ring $\mathbb{Z}[i,1/\sqrt{2}]$ and employing
exact synthesis. We also show that any $n$ qubit unitary over the ring
$\mathbb{Z}[i,1/\sqrt{2}]$ with entries of the form
$(a+b\sqrt{2}+ic+id\sqrt{2})/2^{k}$ can be exactly synthesized using
$O(4^{n}nk)$ Clifford and T gates using two ancillary qubits. This new exact
synthesis algorithm is an improvement over the best known exact synthesis
method by B. Giles and P. Selinger requiring $O(3^{2^{n}}nk)$ elementary gates.


title: Spatiospectral concentration of vector fields on a sphere

abstract:
  We construct spherical vector bases that are bandlimited and spatially
concentrated, or, alternatively, spacelimited and spectrally concentrated,
suitable for the analysis and representation of real-valued vector fields on
the surface of the unit sphere, as arises in the natural and biomedical
sciences, and engineering. Building on the original approach of Slepian,
Landau, and Pollak we concentrate the energy of our function bases into
arbitrarily shaped regions of interest on the sphere, and within certain
bandlimits in the vector spherical-harmonic domain. As with the concentration
problem for scalar functions on the sphere, which has been treated in detail
elsewhere, a Slepian vector basis can be constructed by solving a
finite-dimensional algebraic eigenvalue problem. The eigenvalue problem
decouples into separate problems for the radial and tangential components. For
regions with advanced symmetry such as polar caps, the spectral concentration
kernel matrix is very easily calculated and block-diagonal, lending itself to
efficient diagonalization. The number of spatiospectrally well-concentrated
vector fields is well estimated by a Shannon number that only depends on the
area of the target region and the maximal spherical-harmonic degree or
bandwidth. The spherical Slepian vector basis is doubly orthogonal, both over
the entire sphere and over the geographic target region. Like its scalar
counterparts it should be a powerful tool in the inversion, approximation and
extension of bandlimited fields on the sphere: vector fields such as gravity
and magnetism in the earth and planetary sciences, or electromagnetic fields in
optics, antenna theory and medical imaging.


title:
Nuclear superfluidity in isospin asymmetric matter within the Skyrme
  model

abstract:
  The phase diagram of the superfluid phase coupled to spin singlet (S=0) and
isospin triplet (T=1) states in infinite nuclear matter is analyzed within the
nonrelativistic Skyrme model. We use an approach that allows a unified and
consistent treatment of the particle-hole and particle-particle channels. The
gap equation is solved for the full range of accessible densities, isospin
asymmetries, and temperatures. The characteristic features of each of the
components Tz=0, +1, -1 are emphasized. The search for signatures of a BCS-BEC
crossover yields negative results within the scheme proposed.


title: Bregman Alternating Direction Method of Multipliers

abstract:
  The mirror descent algorithm (MDA) generalizes gradient descent by using a
Bregman divergence to replace squared Euclidean distance. In this paper, we
similarly generalize the alternating direction method of multipliers (ADMM) to
Bregman ADMM (BADMM), which allows the choice of different Bregman divergences
to exploit the structure of problems. BADMM provides a unified framework for
ADMM and its variants, including generalized ADMM, inexact ADMM and Bethe ADMM.
  We establish the global convergence and the $O(1/T)$ iteration complexity for
BADMM. In some cases, BADMM can be faster than ADMM by a factor of
$O(n/\log(n))$. In solving the linear program of mass transportation problem,
BADMM leads to massive parallelism and can easily run on GPU. BADMM is several
times faster than highly optimized commercial software Gurobi.


title: The Heliometer of Rio de Janeiro in Operation - 2010 to 2013

abstract:
  Out of the three quantities that characterize the state of an isolated
gaseous body: pressure, temperature and volume the radius is the only one
directly measurable for the Sun, what is specially true in the optical window
and for ground base measurements. The Heliometer of Observatorio Nacional, in
Rio de Janeiro, measures the distance between two opposite limbs of the Sun in
the same field of view, through the reflection on a 10 cm parabolic mirror
split on its half and forming an appropriate angle. This configuration is free
from optical aberrations and focal variations along the measurement direction.
The mirrors are made on CCZ vitro-ceramic and the telescope structure is of
carbon steel, resulting that there is no flexion or temperature deformation.
The instrument is compact, and can perform hundreds of measurements per duty
day, around all heliolatitudes. It attains an accuracy on the solar radius of
0.01 arcsec, becoming the ideal instrument to monitor from the ground the solar
diameter, and to bridge satellites and astrolabes historical series of data. We
discuss the first years of regular observation, with emphasis on the
instrumental calibrations and on the statistic study of the derived time
series, attitude series, and solar geometry series. On basis of these series we
obtain how well the Heliometer and Solar Astrolabe results are matched.


title:
Lifshitz Tails for Anderson Models with Sign-Indefinite Single-Site
  Potentials

abstract:
  We study the spectral minimum and Lifshitz tails for continuum random
Schr\"{o}dinger operators of the form \begin{equation*}
H_{\om}=-\De+V_{0}+\sum_{i\in\Z^{d}}\om_{i}u(\cdot-i), \end{equation*} where
$V_{0}$ is the periodic potential, $\{\om_{i}\}_{i\in\Z^{d}}$ are i.i.d random
variables and $u$ is the sign-indefinite impurity potential. Recently, this
model has been proven to exhibit Lifshitz tails near the bottom of the spectrum
under the small support assuption of $u$ and the reflection symmetry assumption
of $V_{0}$ and $u$. We here drop the reflection symmetry assumption of $V_{0}$
and $u$. We first give characterizations of the bottom of the spectrum. Then,
we show the existence of Lifshitz tails in the regime where the
characterization of the bottom of the spectrum is explicit. In particular, this
regime covers the reflection symmetry case.


title:
A detailed census of variable stars in the globular cluster NGC 6333
  (M9) from CCD differential photometry

abstract:
  We report CCD $V$ and $I$ time-series photometry of the globular cluster NGC
6333 (M9). The technique of difference image analysis has been used, which
enables photometric precision better than 0.05 mag for stars brighter than $V
\sim 19.0$ mag, even in the crowded central regions of the cluster. The high
photometric precision has resulted in the discovery of two new RRc stars, three
eclipsing binaries, seven long-term variables and one field RRab star behind
the cluster. A detailed identification chart and equatorial coordinates are
given for all the variable stars in the field of our images of the cluster. Our
data together with literature $V$-data obtained in 1994 and 1995 allowed us to
refine considerably the periods for all RR Lyrae stars. The nature of the new
variables is discussed. We argue that variable V12 is a cluster member and an
Anomalous Cepheid. Secular period variations, double mode pulsations and/or the
Blazhko-like modulations in some RRc variables are addressed. Through the light
curve Fourier decomposition of 12 RR Lyrae stars we have calculated a mean
metallicity of [Fe/H]$_{\rm ZW}$=$-1.70 \pm 0.01{\rm(statistical)} \pm
0.14{\rm(systematic)}$ or [Fe/H]$_{UVES}=-1.67 \pm 0.01{\rm(statistical)} \pm
0.19{\rm(systematic)}$.Absolute magnitudes, radii and masses are also estimated
for the RR Lyrae stars.
  A detailed search for SX Phe stars in the Blue Straggler region was conducted
but none were discovered. If SX Phe exist in the cluster then their amplitudes
must be smaller than the detection limit of our photometry.
  The CMD has been corrected for heavy differential reddening using the
detailed extinction map of the cluster of Alonso-Garc\'ia et al. (2012). This
has allowed us to set the mean cluster distance from two independent estimates;
from the RRab and RRc absolute magnitudes, we find $8.04\pm 0.19$ kpc and
$7.88\pm0.30$ kpc respectively.


title:
Hermite spectral method with hyperbolic cross approximations to
  high-dimensional parabolic PDEs

abstract:
  It is well-known that sparse grid algorithm has been widely accepted as an
efficient tool to overcome the "curse of dimensionality" in some degree. In
this note, we first give the error estimate of hyperbolic cross (HC)
approximations with generalized Hermite functions. The exponential convergence
in both regular and optimized hyperbolic cross approximations has been shown.
Moreover, the error estimate of Hermite spectral method to high-dimensional
linear parabolic PDEs with HC approximations has been investigated in the
properly weighted Korobov spaces. The numerical result verifies the exponential
convergence of this approach.


title: Timescape cosmology with radiation fluid

abstract:
  The timescape cosmology represents a potentially viable alternative to the
standard homogeneous cosmology, without the need for dark energy. Although
average cosmic evolution in the timescape scenario only differs substantially
from that of Friedmann-Lemaitre model at relatively late epochs when the
contribution from the energy density of radiation is negligible, a full
solution of the Buchert equations to incorporate radiation is necessary to
smoothly match parameters to the epoch of photon decoupling and to obtain
constraints from cosmic microwave background data. Here we extend the
matter-dominated solution found in earlier work to include radiation, providing
series solutions at early times and an efficient numerical integration strategy
for generating the complete solution. The numerical solution is used to
directly calculate the scale of the sound horizon at decoupling, and at the
baryon drag epoch. The constraints on these scales from the Planck satellite
data yield bounds on the timescape cosmological parameters, which are found to
also agree with the best-fit values from a recent analysis of SDSS-II supernova
data, while avoiding the problem of a primordial lithium-7 abundance anomaly.


title:
Anisotropic Cosmic Ray Diffusion and its Implications for Gamma-Ray
  Astronomy

abstract:
  Analyses of TeV-PeV cosmic ray (CR) diffusion around their sources usually
assume either isotropic diffusion or anisotropic diffusion due to the regular
Galactic magnetic field. We show that none of them are adequate on distances
smaller than the maximal scale Lmax ~ 100 pc of fluctuations in the turbulent
interstellar magnetic field. As a result, we predict anisotropic gamma-ray
emissions around CR proton and electron sources, even for uniform densities of
target gas. The centers of extended emission regions may have non-negligible
offsets from their sources, leading to risks of misidentification. Gamma-rays
from CR filaments have steeper energy spectra than those from surrounding
regions. We point out that gamma-ray telescopes can be used in the future as a
new way to probe and deduce the parameters of the interstellar magnetic field.


title: Dark matter halo formation in the multicomponent dark matter models

abstract:
  This work investigates a set of cosmological collisionless N-body simulations
with featured power spectra of initial perturbations in the context of the
core-cusp and satellites problems. On the studied power spectra some scales of
fluctuations were suppressed. Such spectral features can be caused by
multicomponent dark matter. The density profiles innermost resolved slopes
$\alpha\equiv d \log(\rho) /d \log(r) $ of the five largest haloes were
measured and its dependence on the parameters of the suppression was traced. In
a certain range of the parameters the slopes flatten from initial value of
about -1.2 to -0.6 or even to -0.2 in one of the cases. This qualitatively
demonstrates that (i) profiles shape depends on initial power spectrum and (ii)
this effect may be responsible for the solution of the core-cusp problem. The
suppression of some part of the initial power spectrum also leads to the
decrease of the number of massive subhaloes.


title:
Superconformal Generalization of the Chaotic Inflation Model \lambda
  \phi^4/4 - \xi/ 2 \phi^2 R

abstract:
  A model of chaotic inflation based on the theory of a scalar field with
potential \lambda\phi^4 perfectly matches the observational data if one adds to
it a tiny non-minimal coupling to gravity -\xi/2 \phi^2 R with \xi > 0.002. We
describe embedding of this model into the superconformal theory with
spontaneous breaking of superconformal symmetry, and into supergravity. A model
with small \xi is technically natural: setting the small parameter \xi to zero
leads to a point of enhanced symmetry in the underlying superconformal theory.


title:
Sparse Inverse Covariance Matrix Estimation Using Quadratic
  Approximation

abstract:
  The L1-regularized Gaussian maximum likelihood estimator (MLE) has been shown
to have strong statistical guarantees in recovering a sparse inverse covariance
matrix, or alternatively the underlying graph structure of a Gaussian Markov
Random Field, from very limited samples. We propose a novel algorithm for
solving the resulting optimization problem which is a regularized
log-determinant program. In contrast to recent state-of-the-art methods that
largely use first order gradient information, our algorithm is based on
Newton's method and employs a quadratic approximation, but with some
modifications that leverage the structure of the sparse Gaussian MLE problem.
We show that our method is superlinearly convergent, and present experimental
results using synthetic and real-world application data that demonstrate the
considerable improvements in performance of our method when compared to other
state-of-the-art methods.


title: Sets of Complex Unit Vectors with Two Angles and Distance-Regular Graphs

abstract:
  We study {0,\alpha}-sets, which are sets of unit vectors of $\mathbb{C}^m$ in
which any two distinct vectors have angle 0 or \alpha. We investigate some
distance-regular graphs that provide new constructions of {0,\alpha}-sets using
a method by Godsil and Roy. We prove bounds for the sizes of {0,\alpha}-sets of
flat vectors, and characterize all the distance-regular graphs that yield
{0,\alpha}-sets meeting the bounds at equality.


title: Superconformal generalizations of the Starobinsky model

abstract:
  We find a way to represent the Starobinsky model in terms of a simple
conformally invariant theory with spontaneous symmetry breaking. We also
present a superconformal theory, which, upon spontaneous breaking of the
superconformal symmetry, provides a consistent supergravity generalization of
the Starobinsky model.


title: Weights for Objects of Monoids

abstract:
  The main objective of the paper is to define the construction of the object
of monoids, over a monoidal category object in any 2-category with finite
products, as a weighted limit. To simplify the definition of the weight, we use
matrices of symmetric (possibly colored) operads that define some auxiliary
categories and 2-categories. Systematic use of these matrices of operads allows
us to define several similar objects as weighted limits. We show, among others,
that the constructions of the object of bi-monoids over a symmetric monoidal
category object or the object of actions of monoids along an action of a
monoidal category object can be also described as weighted limits.


title: On the 'Reality' of Observable Properties

abstract:
  This note contains some initial work on attempting to bring recent
developments in the foundations of quantum mechanics concerning the nature of
the wavefunction within the scope of more logical and structural methods. A
first step involves generalising and reformulating a criterion for the reality
of the wavefunction proposed by Harrigan & Spekkens, which was central to the
PBR theorem. The resulting criterion has several advantages, including the
avoidance of certain technical difficulties relating to sets of measure zero.
By considering the 'reality' not of the wavefunction but of the observable
properties of any ontological physical theory a novel characterisation of
non-locality and contextuality is found.
  Secondly, a careful analysis of preparation independence, one of the key
assumptions of the PBR theorem, leads to an analogy with Bell locality, and
thence to a proposal to weaken it to an assumption of
`no-preparation-signalling' in analogy with no-signalling. This amounts to
introducing non-local correlations in the joint ontic state, which is, at
least, consistent with the Bell and Kochen-Specker theorems. The question of
whether the PBR result can be strengthened to hold under this relaxed
assumption is therefore posed.


title: LHC constraints on dark matter with (130 GeV) gamma ray lines

abstract:
  Dark matter annihilation into photons in our galaxy would constitute an
exciting indirect signal of its existence, as underscored by tentative evidence
for 130 GeV dark matter in Fermi/LAT data. Models that give a large
annihilation cross section into photons typically require the dark matter to
couple to, or be composed of, new charged particles, that can be produced in
colliders. We consider the LHC constraints on some representative models of
these types, including the signals of same-sign dileptons, opposite-sign
dileptons, events mimicking the production and decay of excited leptons,
four-photon events, resonant production of composite vectors decaying into two
photons, and monophoton events.


title:
Black hole variability and the star formation-AGN connection: Do all
  star-forming galaxies host an AGN?

abstract:
  We investigate the effect of active galactic nucleus (AGN) variability on the
observed connection between star formation and black hole accretion in
extragalactic surveys. Recent studies have reported relatively weak
correlations between observed AGN luminosities and the properties of AGN hosts,
which has been interpreted to imply that there is no direct connection between
AGN activity and star formation. However, AGNs may be expected to vary
significantly on a wide range of timescales (from hours to Myr) that are far
shorter than the typical timescale for star formation (>~100 Myr). This
variability can have important consequences for observed correlations. We
present a simple model in which all star-forming galaxies host an AGN when
averaged over ~100 Myr timescales, with long-term average AGN accretion rates
that are perfectly correlated with the star formation rate (SFR). We show that
reasonable prescriptions for AGN variability reproduce the observed weak
correlations between SFR and L_AGN in typical AGN host galaxies, as well as the
general trends in the observed AGN luminosity functions, merger fractions, and
measurements of the average AGN luminosity as a function of SFR. These results
imply there may be a tight connection between AGN activity and SFR over galaxy
evolution timescales, and that the apparent similarities in rest-frame colors,
merger rates, and clustering of AGNs compared to "inactive" galaxies may be due
primarily to AGN variability. The results provide motivation for future deep,
wide extragalactic surveys that can measure the distribution of AGN accretion
rates as a function of SFR.


title: Nonlinear structure formation in the Cubic Galileon gravity model

abstract:
  We model the linear and nonlinear growth of large scale structure in the
Cubic Galileon gravity model, by running a suite of N-body cosmological
simulations using the {\tt ECOSMOG} code. Our simulations include the
Vainshtein screening effect, which reconciles the Cubic Galileon model with
local tests of gravity. In the linear regime, the amplitude of the matter power
spectrum increases by $\sim 25%$ with respect to the standard $\Lambda$CDM
model today. The modified expansion rate accounts for $\sim 20%$ of this
enhancement, while the fifth force is responsible for only $\sim 5%$. This is
because the effective unscreened gravitational strength deviates from standard
gravity only at late times, even though it can be twice as large today. In the
nonlinear regime ($k \gtrsim 0.1 h\rm{Mpc}^{-1}$), the fifth force leads to
only a modest increase ($\lesssim 8%$) in the clustering power on all scales
due to the very efficient operation of the Vainshtein mechanism. Such a strong
effect is typically not seen in other models with the same screening mechanism.
The screening also results in the fifth force increasing the number density of
halos by less than 10%, on all mass scales. Our results show that the screening
does not ruin the validity of linear theory on large scales which anticipates
very strong constraints from galaxy clustering data. We also show that, whilst
the model gives an excellent match to CMB data on small angular scales ($l
\gtrsim 50$), the predicted integrated Sachs-Wolf effect is in tension with
Planck/WMAP results.


title: Classical 3-loop 2-body diagrams

abstract:
  As part of the study of the two-body problem in Einstein's gravity, the
fourth post-Newtonian order (4PN) of the two-body effective action is being
computed presently by both effective field theory (EFT) methods and others.
Diagrams with 3 (or 4) classical loops appear to be a significant obstacle. In
this paper we develop a method to compute such 3-loop diagrams and demonstrate
it through a specific diagram. We reduce the classical diagrams through
shrinking the body worldlines to a form more familiar in Quantum Field Theory.
A key ingredient in the evaluation is the Integration By Parts method for
Feynman integrals.


title:
A simple, quantitative method to infer the minimum atmospheric height of
  small exoplanets

abstract:
  Amongst the many hundreds of transiting planet candidates discovered by the
Kepler Mission, one finds a large number of candidates with sizes between that
of the Earth and Neptune. The composition of these worlds is not immediately
obvious with no Solar System analog to draw upon and there exists some
ambiguity as to whether a given candidate is a rocky Super-Earth or a
gas-enveloped Mini-Neptune. The potential scientific value and observability of
the atmospheres of these two classes of worlds varies significantly and given
the sheer number of candidates in this size-range, there is evidently a need
for a quick, simple metric to rank whether the planets have an extended
atmosphere or not. In this work, we propose a way to calculate the 'minimum
atmospheric height' (R_MAH) using only a planet's radius and mass as inputs. We
assume and exploit the boundary condition that the bulk composition of a
solid/liquid Super-Earth cannot be composed of a material lighter than that of
water. Mass-radius loci above a pure-water composition planet correspond to
R_MAH>0. The statistical confidence of a planet maintaining an extended
atmosphere can be therefore easily calculated to provide a simple ranking of
target planets for follow-up observations. We also discuss how this metric can
be useful in the interpretation of the spectra of observed planetary
atmospheres.


title:
Turbulence In the Outer Regions of Protoplanetary Disks. II. Strong
  Accretion Driven by a Vertical Magnetic Field

abstract:
  We carry out a series of local, vertically stratified shearing box
simulations of protoplanetary disks that include ambipolar diffusion and a net
vertical magnetic field. The ambipolar diffusion profiles we employ correspond
to 30AU and 100AU in a minimum mass solar nebula (MMSN) disk model, which
consists of a far-UV-ionized surface layer and low-ionization disk interior.
These simulations serve as a follow up to Simon et al. (2013), in which we
found that without a net vertical field, the turbulent stresses that result
from the magnetorotational instability (MRI) are too weak to account for
observed accretion rates. The simulations in this work show a very strong
dependence of the accretion stresses on the strength of the background vertical
field; as the field strength increases, the stress amplitude increases. For gas
to magnetic pressure ratios of 1e4 and 1e5, we find accretion rates between
1e-8 and 1e-7 solar masses per year. These accretion rates agree with
observational constraints, suggesting a vertical magnetic field strength
between 60 and 200 microgauss at 30AU and 10 and 30 microgauss at 100AU in a
MMSN disk. Furthermore, the stress has a non-negligible component due to a
magnetic wind. For sufficiently strong vertical field strengths, MRI turbulence
is quenched, and the flow becomes largely laminar, with accretion proceeding
through large scale correlations in the radial and toroidal field components as
well as through the magnetic wind. In all simulations, the presence of a low
ionization region near the disk mid-plane, which we call the ambipolar damping
zone, results in reduced stresses there.


title:
Gapped Symmetry Preserving Surface-State for the Electron Topological
  Insulator

abstract:
  It is well known that the 3D electronic topological insulator (TI) with
charge-conservation and time-reversal symmetry cannot have a trivial insulating
surface that preserves symmetry. It is often implicitly assumed that if the TI
surface preserves both symmetries then it must be gapless. Here we show that it
is possible for the TI surface to be both gapped and symmetry-preserving, at
the expense of having surface-topological order. In contrast to analogous
bosonic topological insulators, this symmetric surface topological order is
intrinsically non-Abelian. We show that the surface-topological order provides
a complete non-perturbative definition of the electron TI that transcends a
free-particle band-structure picture, and could provide a useful perspective
for studying strongly correlated topological Mott insulators.


title: Landau Levels, Anisotropy and Holography

abstract:
  We analyze properties of field theories dual to extremal black branes in
(4+1) dimensions with anisotropic near-horizon geometries. Such gravity
solutions were recently shown to fall into nine classes which align with the
Bianchi classification of real three-dimensional Lie algebras. As a warmup we
compute constraints on critical exponents from energy conditions in the bulk
and scalar two point functions for a general type I metric, which has
translation invariance but broken rotations. We also comment on the divergent
nature of tidal forces in general Bianchi-type metrics. Then we come to our
main focus: extremal branes whose near-horizon isometries are those of the
Heisenberg algebra (type II). We find hyperscaling-violating solutions with
type II isometries in (4+1)-dimensions. We show that scale invariant
(4+1)-dimensional type II metrics are related by Kaluza-Klein reduction to more
symmetric $AdS_2\times R^2$ and (3+1)-dimensional hyperscaling-violating
spacetimes. These solutions generically have $\theta \leq 0$. We discuss how
one can obtain flows from UV CFTs to Bianchi-type spacetimes in the IR via the
Higgs mechanism, as well as potential inhomogeneous instabilities of type II.
Finally, we compute two-point functions of massive and massless scalar
operators in the dual field theory and find that they exhibit the behavior of a
theory with Landau levels.


title: Astrometric orbit of a low-mass companion to an ultracool dwarf

abstract:
  Little is known about the existence of extrasolar planets around ultracool
dwarfs. Furthermore, binary stars with Sun-like primaries and very low-mass
binaries composed of ultracool dwarfs show differences in the distributions of
mass ratio and orbital separation that can be indicative of distinct formation
mechanisms. Using FORS2/VLT optical imaging for high precision astrometry we
are searching for planets and substellar objects around ultracool dwarfs to
investigate their multiplicity properties for very low companion masses. Here
we report astrometric measurements with an accuracy of two tenths of a
milli-arcsecond over two years that reveal orbital motion of the nearby L1.5
dwarf DENIS-P J082303.1-491201 located at 20.77 +/- 0.08 pc caused by an unseen
companion that revolves about its host on an eccentric orbit in 246.4 +/- 1.4
days. We estimate the L1.5 dwarf to have 7.5 +/- 0.7 % of the Sun's mass that
implies a companion mass of 28 +/- 2 Jupiter masses. This new system has the
smallest mass ratio (0.36 +/- 0.02) of known very low-mass binaries with
characterised orbits. With this discovery we demonstrate 200 micro-arcsecond
astrometry over an arc-minute field and over several years that is sufficient
to discover sub-Jupiter mass planets around ultracool dwarfs. We also show that
the achieved parallax accuracy of < 0.4 % makes it possible to remove distance
as a dominant source of uncertainty in the modelling of ultracool dwarfs.


title: A geometric crescent model for black hole images

abstract:
  The Event Horizon Telescope (EHT), a global very long baseline interferometry
array operating at millimetre wavelengths, is spatially resolving the immediate
environments of black holes for the first time. The current observations of the
Galactic center black hole, Sagittarius A* (Sgr A*), and M87 have been
interpreted in terms of either geometric models (e.g., a symmetric Gaussian) or
detailed calculations of the appearance of black hole accretion flows. The
former are not physically motivated, while the latter are subject to large
systematic uncertainties. Motivated by the dominant relativistic effects of
Doppler beaming and gravitational lensing in many calculations, we propose a
geometric crescent model for black hole images. We show that this simple model
provides an excellent statistical description of the existing EHT data of Sgr
A* and M87, superior to other geometric models for Sgr A*. It also
qualitatively matches physically predicted models, bridging accretion theory
and observation. Based on our results, we make predictions for the
detectability of the black hole shadow, a signature of strong gravity, in
future observations.


title:
KAT-7 Science Verification: Using HI Observations of NGC 3109 to
  Understand its Kinematics and Mass Distribution

abstract:
  HI observations of the Magellanic-type spiral NGC 3109, obtained with the
seven dish Karoo Array Telescope (KAT-7), are used to analyze its mass
distribution. Our results are compared to what is obtained using VLA data.
KAT-7 is the precursor of the SKA pathfinder MeerKAT, which is under
construction. The short baselines and low system temperature of the telescope
make it sensitive to large scale low surface brightness emission. The new
observations with KAT-7 allow the measurement of the rotation curve of NGC 3109
out to 32', doubling the angular extent of existing measurements. A total HI
mass of 4.6 x 10^8 Msol is derived, 40% more than what was detected by the VLA
observations.
  The observationally motivated pseudo-isothermal dark matter (DM) halo model
can reproduce very well the observed rotation curve but the cosmologically
motivated NFW DM model gives a much poorer fit to the data. While having a more
accurate gas distribution has reduced the discrepancy between the observed RC
and the MOdified Newtonian Dynamics (MOND) models, this is done at the expense
of having to use unrealistic mass-to-light ratios for the stellar disk and/or
very large values for the MOND universal constant a0. Different distances or HI
contents cannot reconcile MOND with the observed kinematics, in view of the
small errors on those two quantities. As for many slowly rotating gas-rich
galaxies studied recently, the present result for NGC 3109 continues to pose a
serious challenge to the MOND theory.


title: Resummation and S-duality in N=4 SYM

abstract:
  We consider the problem of resumming the perturbative expansions for
anomalous dimensions of low twist, non-BPS operators in four dimensional N=4
supersymmetric Yang-Mills theories. The requirement of S-duality invariance
imposes considerable restrictions on any such resummation. We introduce several
prescriptions that produce interpolating functions on the upper half plane that
are compatible with a subgroup of the full duality group. These lead to
predictions for the anomalous dimensions at all points in the fundamental
domain of the complex gauge coupling, and in particular at the
duality-invariant values \tau=i and \tau=exp(i\pi/3). For low-rank gauge
groups, the predictions are compatible with the bounds derived by conformal
bootstrap methods for these anomalous dimensions; within numerical errors, they
are in good agreement with the conjecture that said bounds are saturated at a
duality-invariant point. We also find that the anomalous dimensions of the
lowest twist operators lie within an extremely narrow window around a straight
line as we vary the moduli of the theory over the two dimensional fundamental
domain.


title: Non-Decoupling MSSM Higgs Sector and Light Superpartners

abstract:
  In the ``non-decoupling'' region of the Higgs sector in MSSM, the heavier
CP-even Higgs boson (H^0) is Standard-Model-like and close to the charged Higgs
bosons (H^\pm) in mass, while other neutral Higgs bosons (h^0,A^0) are lighter
and near the Z mass. This scenario is consistent with the current Higgs search
limits, although the improved sensitivity for a light charged Higgs boson
search t -> H^+ b may result in certain degree of tension. We demonstrate that
it can pass the stringent flavor constraints, provided there are other light
SUSY particles to contribute in the loop induced processes. In turn, the
non-decoupling Higgs sector implies the existence of light (left-handed) stop,
sbottom and Wino-like gauginos, with mass all below 250 GeV. These light
super-partners can still escape the current SUSY searches at the LHC. Dedicated
searches for soft decay products should be devised for the LHC experiments to
improve the searching sensitivity. The ILC would be able to cover the full
spectrum region. The solutions for the viable SUSY parameters result from
subtle cancellations and are often missed by the generic multiple dimensional
scans, highlighting the importance of theoretical guidance in search for such
special cases.


title:
A Time-Reversal Invariant Topological Phase at the Surface of a 3D
  Topological Insulator

abstract:
  A 3D fermionic topological insulator has a gapless Dirac surface state
protected by time-reversal symmetry and charge conservation symmetry. The
surface state can be gapped by introducing ferromagnetism to break
time-reversal symmetry, introducing superconductivity to break charge
conservation, or entering a topological phase. In this paper, we construct a
minimal gapped topological phase that preserves both time-reversal and charge
conservation symmetries and supports Ising-type non-Abelian anyons. This phase
can be understood heuristically as emerging from a surface s-wave
superconducting state via the condensation of eight-vortex composites. The
topological phase inherits vortices supporting Majorana zero modes from the
surface superconducting state. However, since it is time-reversal invariant,
the surface topological phase is a distinct phase from the Ising topological
phase, which can be viewed as a quantum-disordered spin-polarized p_x + i p_y
superconductor. We discuss the anyon model of this topological phase and the
manner in which time-reversal symmetry is realized in it. We also study the
interfaces between the topological state and other surface gapped phases.


title: A preferred ground state for the scalar field in de Sitter space

abstract:
  We investigate a recent proposal for a distinguished vacuum state of a free
scalar quantum field in an arbitrarily curved spacetime, known as the
Sorkin-Johnston (SJ) vacuum, by applying it to de Sitter space. We derive the
associated two-point functions on both the global and Poincar\'e (cosmological)
patches in general d+1 dimensions. In all cases where it is defined, the SJ
vacuum belongs to the family of de Sitter invariant alpha-vacua. We obtain
different states depending on the spacetime dimension, mass of the scalar
field, and whether the state is evaluated on the global or Poincar\'e patch. We
find that the SJ vacuum agrees with the Euclidean/Bunch-Davies state for heavy
("principal series") fields on the global patch in even spacetime dimensions.
We also compute the SJ vacuum on a causal set corresponding to a causal diamond
in 1+1 dimensional de Sitter space. Our simulations show that the mean of the
SJ two-point function on the causal set agrees well with its expected continuum
counterpart.


title: Quantum Instability of the Emergent Universe

abstract:
  We perform a semi-classical analysis of the Emergent Universe scenario for
inflation. Fixing the background, and taking the inflaton to be homogenous, we
cast the inflaton's evolution as a one-dimensional quantum mechanics problem.
We find that the tuning required over a long time scale for this inflationary
scenario is unstable quantum mechanically. Considering the inflaton field value
as a wavepacket, the spreading of the wavepacket destroys any chance of both
starting and ending with a well-formed state. Thus, one cannot have an Einstein
static universe to begin with that evolves into a well-defined beginning to
inflation a long time later.


title: Spherical collapse and halo mass function in f(R) theories

abstract:
  We compute the critical density of collapse for spherically symmetric
overdensities in a class of f(R) modified gravity models. For the first time we
evolve the Einstein, scalar field and non-linear fluid equations, making the
minimal simplifying assumptions that the metric potentials and scalar field
remain quasi-static throughout the collapse. Initially evolving a top hat
profile, we find that the density threshold for collapse depends significantly
on the initial conditions imposed, specifically the choice of size and shape.
By imposing `natural' initial conditions, we obtain a fitting function for the
spherical collapse delta_c as a function of collapse redshift, mass of the
overdensity and f_{R0}, the background scalar field value at z=0. By extending
delta_c into drifting and diffusing barrier within the context of excursion set
theory, we obtain a realistic mass function that might be used to confront this
class of scalar-tensor models with observations of dark matter halos. The
proposed analytic formula for the halo mass function was tested against Monte
Carlo random walks for a wide class of moving barriers and can therefore be
applied to other modified gravity theories.


title: Standard Model Vacuum Stability and Weyl Consistency Conditions

abstract:
  At high energy the standard model possesses conformal symmetry at the
classical level. This is reflected at the quantum level by relations between
the different beta functions of the model. These relations are known as the
Weyl consistency conditions. We show that it is possible to satisfy them order
by order in perturbation theory, provided that a suitable coupling constant
counting scheme is used. As a direct phenomenological application, we study the
stability of the standard model vacuum at high energies and compare with
previous computations violating the Weyl consistency conditions.


title: Lagrangian structures on mapping stacks and semi-classical TFTs

abstract:
  We extend a recent result of Pantev-Toen-Vaquie-Vezzosi, who constructed
shifted symplectic structures on derived mapping stacks having a Calabi-Yau
source and a shifted symplectic target. Their construction gives a clear
conceptual framework for the so-called AKSZ formalism.
  We extend the PTVV construction to derived mapping stacks with boundary
conditions, which is required in most applications to quantum field theories
(see e.g. the work of Cattaneo-Felder on the Poisson sigma model, and the
recent work of Cattaneo-Mnev-Reshetikhin). We provide many examples of
Lagrangian and symplectic structures that can be recovered in this way.
  We finally give an application to topological field theories (TFTs). We
expect that our approach will help to rigorously constuct a 2 dimensional TFT
introduced by Moore and Tachikawa. A subsequent paper will be devoted to the
construction of fully extended TFTs (in the sense of Baez-Dolan and Lurie) from
mapping stacks.


title: Loops in reheating and cosmological perturbations

abstract:
  We show that in scalar field inflationary models, the loop corrections in
reheating corresponding to the decay of the inflaton can cause nontrivial
superhorizon evolution of the curvature perturbation. The effect turns out to
be prominent when the decay occurs via parametric resonance, even indicating
the breakdown of the perturbation theory, as we demonstrate in a specific
model.


title:
Pre-main-sequence isochrones -- II. Revising star and planet formation
  timescales

abstract:
  We have derived ages for 13 young (<30 Myr) star-forming regions and find
they are up to a factor two older than the ages typically adopted in the
literature. This result has wide-ranging implications, including that
circumstellar discs survive longer (~10-12 Myr) and that the average Class I
lifetime is greater (~1 Myr) than currently believed.
  For each star-forming region we derived two ages from colour-magnitude
diagrams. First we fitted models of the evolution between the zero-age
main-sequence and terminal-age main-sequence to derive a homogeneous set of
main-sequence ages, distances and reddenings with statistically meaningful
uncertainties. Our second age for each star-forming region was derived by
fitting pre-main-sequence stars to new semi-empirical model isochrones. For the
first time (for a set of clusters younger than 50 Myr) we find broad agreement
between these two ages, and since these are derived from two distinct mass
regimes that rely on different aspects of stellar physics, it gives us
confidence in the new age scale. This agreement is largely due to our adoption
of empirical colour-Teff relations and bolometric corrections for
pre-main-sequence stars cooler than 4000 K.
  The revised ages for the star-forming regions in our sample are: ~2 Myr for
NGC 6611 (Eagle Nebula; M 16), IC 5146 (Cocoon Nebula), NGC 6530 (Lagoon
Nebula; M 8), and NGC 2244 (Rosette Nebula); ~6 Myr for {\sigma} Ori, Cep OB3b,
and IC 348; ~10 Myr for {\lambda} Ori (Collinder 69); ~11 Myr for NGC 2169; ~12
Myr for NGC 2362; ~13 Myr for NGC 7160; ~14 Myr for {\chi} Per (NGC 884); and
~20 Myr for NGC 1960 (M 36).


title:
Classification of interacting electronic topological insulators in three
  dimensions

abstract:
  A fundamental open problem in condensed matter physics is how the dichotomy
between conventional and topological band insulators is modified in the
presence of strong electron interactions. We show that there are 6 new
electronic topological insulators that have no non-interacting counterpart.
Combined with the previously known band-insulators, these produce a total of 8
topologically distinct phases. Two of the new topological insulators have a
simple physical description as Mott insulators in which the electron spins form
spin analogs of the familiar topological band-insulator. The remaining are
obtained as combinations of these two `topological paramagnets' and the
topological band insulator. We prove that these 8 phases form a complete list
of all possible interacting topological insulators, and are classified by a
Z_2^3 group-structure. Experimental signatures are also discussed for these
phases.


title: A Higgs--Saw Mechanism as a Source for Dark Energy

abstract:
  Motivated by the see-saw mechanism for neutrinos which naturally generates
small neutrino masses, we explore how a small GUT-scale mixing between the
Standard Model Higgs and an otherwise massless hidden sector scalar can
naturally generate a small mass and VEV for the new scalar which produces a
false vacuum energy density contribution comparable to that of the observed
dark energy dominating the current expansion of the Universe. The new scalar
produces no discernible signatures in existing terrestrial experiments so that
one may have to rely on other cosmological tests of this idea.


title:
The impact of edges and dopants on the work function of graphene
  nanostructures. The way to high electronic emission from pure carbon medium

abstract:
  The impact of the edges and presence of dopants to the work function (WF) of
graphene nanoribbons (GNR) and nanoflakes was studied by an ab initio approach.
The strong dependence of the WF upon the GNR structure was found and a
promising character for the field emission by the donor type impurities was
observed. Basing on the predominant impact of the nanostructure edges to the
emission properties, the small graphene flakes were investigated as a possible
source for the electron emission. The obtained weak dependence of the low WF
values of the graphene flakes on their size and shape allows to suggest that
the pure carbon medium with high and uniform emission properties can be
fabricated by today technology.


title:
Testing the role of the Barbero-Immirzi parameter and the choice of
  connection in Loop Quantum Gravity

abstract:
  We study the role of the Barbero-Immirzi parameter $\gamma$ and the choice of
connection in the construction of (a symmetry-reduced version of) loop quantum
gravity. We start with the four-dimensional Lorentzian Holst action that we
reduce to three dimensions in a way that preserves the presence of $\gamma$. In
the time gauge, the phase space of the resulting three-dimensional theory
mimics exactly that of the four-dimensional one. Its quantization can be
performed, and on the kinematical Hilbert space spanned by SU(2) spin network
states the spectra of geometric operators are discrete and $\gamma$-dependent.
However, because of the three-dimensional nature of the theory, its SU(2)
Ashtekar-Barbero Hamiltonian constraint can be traded for the flatness
constraint of an sl(2,C) connection, and we show that this latter has to
satisfy a linear simplicity-like condition analogous to the one used in the
construction of spin foam models. The physically relevant solution to this
constraint singles out the non-compact subgroup SU(1,1), which in turn leads to
the disappearance of the Barbero-Immirzi parameter and to a continuous length
spectrum, in agreement with what is expected from Lorentzian three-dimensional
gravity.


title: Is F-term hybrid inflation natural within minimal supersymmetric SO(10)?

abstract:
  We examine whether F-term supersymmetric hybrid inflation can be embedded
within the minimal SO(10) model, in a natural way. We show that none of the
singlets of the Standard Model symmetries in the minimal set of SO(10)
representations can satisfy the conditions which are necessary for a scalar
field to play the role of the inflaton. As a consequence, one has to introduce
an extra scalar field, which however may spoil the naturalness of inflation
within the context of SO(10). Nevertheless, if we add an extra scalar field, we
are then able to construct a model that can accommodate flat directions while
it preserves the stability of the inflationary valley.


title: ABJM amplitudes and WL at finite N

abstract:
  We evaluate ABJM observables at two loops, for any value of the rank N of the
gauge group. We compute the color subleading contributions to the four-point
scattering amplitude in ABJM at two loops. Contrary to the four dimensional
case, IR divergent N-subleading contributions are proportional to leading poles
in the regularization parameter. We then exploit the non-planar calculation for
the amplitude to derive an expression for the two-loop Sudakov form factor at
any N. In the planar limit the result coincides with the one recently obtained
in literature by using Feynman diagrams and unitarity. Finally, we analyze the
subleading contributions to the light-like four-cusps Wilson loop and interpret
the result in terms of the non-abelian exponentiation theorem. All these
perturbative results satisfy the uniform transcendentality principle, hinting
at its validity in ABJM beyond the planar limit.


title:
The Scientific Reach of Multi-Ton Scale Dark Matter Direct Detection
  Experiments

abstract:
  The next generation of large scale WIMP direct detection experiments have the
potential to go beyond the discovery phase and reveal detailed information
about both the particle physics and astrophysics of dark matter. We report here
on early results arising from the development of a detailed numerical code
modeling the proposed DARWIN detector, involving both liquid argon and xenon
targets. We incorporate realistic detector physics, particle physics and
astrophysical uncertainties and demonstrate to what extent two targets with
similar sensitivities can remove various degeneracies and allow a determination
of dark matter cross sections and masses while also probing rough aspects of
the dark matter phase space distribution. We find that, even assuming dominance
of spin-independent scattering, multi-ton scale experiments still have
degeneracies that depend sensitively on the dark matter mass, and on the
possibility of isospin violation and inelasticity in interactions. We find that
these experiments are best able to discriminate dark matter properties for dark
matter masses less than around 200 GeV. In addition, and somewhat surprisingly,
the use of two targets gives only a small improvement (aside from the advantage
of different systematics associated with any claimed signal) in the ability to
pin down dark matter parameters when compared with one target of larger
exposure.


title: Chiral asymmetry in QED matter in a magnetic field

abstract:
  We calculate the electron self-energy in a magnetized QED plasma to the
leading perturbative order in the coupling constant and to the linear order in
an external magnetic field. We find that the chiral asymmetry of the normal
ground state of the system is characterized by two new Dirac structures. One of
them is the familiar chiral shift previously discussed in the
Nambu--Jona-Lasinio model. The other structure is new. It formally looks like
that of the chiral chemical potential but is an odd function of the
longitudinal component of the momentum, directed along the magnetic field. The
origin of this new parity-even chiral structure is directly connected with the
long-range character of the QED interaction. The form of the Fermi surface in
the weak magnetic field is determined.


title:
Spectra of geometric operators in three-dimensional LQG: From discrete
  to continuous

abstract:
  We study and compare the spectra of geometric operators (length and area) in
the quantum kinematics of two formulations of three-dimensional Lorentzian loop
quantum gravity. In the SU(2) Ashtekar-Barbero framework, the spectra are
discrete and depend on the Barbero-Immirzi parameter $\gamma$ exactly like in
the four-dimensional case. However, we show that when working with the
self-dual variables and imposing the reality conditions the spectra become
continuous and $\gamma$-independent.


title: Program for quantum wave-packet dynamics with time-dependent potentials

abstract:
  We present a program to simulate the dynamics of a wave packet interacting
with a time-dependent potential. The time-dependent Schr\"odinger equation is
solved on a one-, two-, or three-dimensional spatial grid using the split
operator method. The program can be compiled for execution either on a single
processor or on a distributed-memory parallel computer.


title:
Detecting initial system-environment correlations: Performance of
  various distance measures for quantum states

abstract:
  We study the time evolution of four distance measures in the presence of
initial systemenvironment correlations. It is well-known that the trace
distance between two quantum states of an open system may increase due to
initial correlations which leads to a breakdown of the contractivity of the
reduced dynamics. Here we compare and analyze, for two different models, the
time evolution of the trace distance, the Bures metric, the Hellinger distance
and the Jensen-Shannon divergence regarding an increase above their initial
values, witnessing initial correlations. This work generalizes, deepens and
corrects the study performed by Dajka et al. [Phys. Rev. A 84 032120 (2011)]
and thereby reveals generic features of the considered distance measures with
respect to the capability of detecting initial system-environment correlations.


title: Coisotropic submanifolds and dual pairs

abstract:
  The Poisson sigma model is a widely studied two-dimensional topological field
theory. This note shows that boundary conditions for the Poisson sigma model
are related to coisotropic submanifolds (a result announced in
[math.QA/0309180]) and that the corresponding reduced phase space is a
(possibly singular) dual pair between the reduced spaces of the given two
coisotropic submanifolds. In addition the generalization to a more general
tensor field is considered and it is shown that the theory produces Lagrangian
evolution relations if and only if the tensor field is Poisson.


title:
Symmetry Enforced Non-Abelian Topological Order at the Surface of a
  Topological Insulator

abstract:
  The surfaces of three dimensional topological insulators (3D TIs) are
generally described as Dirac metals, with a single Dirac cone. It was
previously believed that a gapped surface implied breaking of either time
reversal $\mathcal T$ or U(1) charge conservation symmetry. Here we discuss a
novel possibility in the presence of interactions, a surface phase that
preserves all symmetries but is nevertheless gapped and insulating. Then the
surface must develop topological order of a kind that cannot be realized in a
2D system with the same symmetries. We discuss candidate surface states -
non-Abelian Quantum Hall states which, when realized in 2D, have
$\sigma_{xy}=1/2$ and hence break $\mathcal T$ symmetry. However, by
constructing an exactly soluble 3D lattice model, we show they can be realized
as $\mathcal T$ symmetric surface states. The corresponding 3D phases are
confined, and have $\theta=\pi$ magnetoelectric response. Two candidate states
have the same 12 particle topological order, the (Read-Moore) Pfaffian state
with the neutral sector reversed, which we term T-Pfaffian topological order,
but differ in their $\mathcal T$ transformation. Although we are unable to
connect either of these states directly to the superconducting TI surface, we
argue that one of them describes the 3D TI surface, while the other differs
from it by a bosonic topological phase. We also discuss the 24 particle
Pfaffian-antisemion topological order (which can be connected to the
superconducting TI surface) and demonstrate that it can be realized as a
$\mathcal T$ symmetric surface state.


title: On Brauer groups of double covers of ruled surfaces

abstract:
  Let X be a smooth double cover of a geometrically ruled surface defined over
a separably closed field of characteristic different from 2. The main result of
this paper is a finite presentation of the 2-torsion in the Brauer group of X
with generators given by central simple algebras over the function field of X
and relations coming from the N\'eron-Severi group of X. In particular, the
result gives a central simple algebra representative for the unique nontrivial
Brauer class on any Enriques surface. An example demonstrating the applications
to the study of rational points is given.


title:
Global Stabilization of Nonlinear Delay Systems With a Compact Absorbing
  Set

abstract:
  Predictor-based stabilization results are provided for nonlinear systems with
input delays and a compact absorbing set. The control scheme consists of an
inter-sample predictor, a global observer, an approximate predictor, and a
nominal controller for the delay-free case. The control scheme is applicable
even to the case where the measurement is sampled and possibly delayed. The
closed-loop system is shown to have the properties of global asymptotic
stability and exponential convergence in the disturbance-free case, robustness
with respect to perturbations of the sampling schedule, and robustness with
respect to measurement errors. In contrast to existing predictor feedback laws,
the proposed control scheme utilizes an approximate predictor of a dynamic type
which is expressed by a system described by Integral Delay Equations.
Additional results are provided for systems that can be transformed to systems
with a compact absorbing set by means of a preliminary predictor feedback.


title: Pointing LISA-like gravitational wave detectors

abstract:
  Space-based gravitational wave detectors based on the Laser Interferometer
Space Antenna (LISA) design operate by synthesizing one or more interferometers
from fringe velocity measurements generated by changes in the light travel time
between three spacecraft in a special set of drag-free heliocentric orbits.
These orbits determine the inclination of the synthesized interferometer with
respect to the ecliptic plane. Once these spacecraft are placed in their
orbits, the orientation of the interferometers at any future time is fixed by
Kepler's Laws based on the initial orientation of the spacecraft constellation,
which may be freely chosen. Over the course of a full solar orbit, the initial
orientation determines a set of locations on the sky were the detector has
greatest sensitivity to gravitational waves as well as a set of locations where
nulls in the detector response fall. By artful choice of the initial
orientation, we can choose to optimize or suppress the antennas sensitivity to
sources whose location may be known in advance (e.g., the Galactic Center or
globular clusters).


title: Minimum-variance multitaper spectral estimation on the sphere

abstract:
  We develop a method to estimate the power spectrum of a stochastic process on
the sphere from data of limited geographical coverage. Our approach can be
interpreted either as estimating the global power spectrum of a stationary
process when only a portion of the data are available for analysis, or
estimating the power spectrum from local data under the assumption that the
data are locally stationary in a specified region. Restricting a global
function to a spatial subdomain -- whether by necessity or by design -- is a
windowing operation, and an equation like a convolution in the spectral domain
relates the expected value of the windowed power spectrum to the underlying
global power spectrum and the known power spectrum of the localization window.
The best windows for the purpose of localized spectral analysis have their
energy concentrated in the region of interest while possessing the smallest
effective bandwidth as possible. Solving an optimization problem in the sense
of Slepian (1960) yields a family of orthogonal windows of diminishing
spatiospectral localization, the best concentrated of which we propose to use
to form a weighted multitaper spectrum estimate in the sense of Thomson (1982).
Such an estimate is both more representative of the target region and reduces
the estimation variance when compared to estimates formed by any single
bandlimited window. We describe how the weights applied to the individual
spectral estimates in forming the multitaper estimate can be chosen such that
the variance of the estimate is minimized.


title:
A spatiospectral localization approach to estimating potential fields on
  the surface of a sphere from noisy, incomplete data taken at satellite
  altitudes

abstract:
  Satellites mapping the spatial variations of the gravitational or magnetic
fields of the Earth or other planets ideally fly on polar orbits, uniformly
covering the entire globe. Thus, potential fields on the sphere are usually
expressed in spherical harmonics, basis functions with global support. For
various reasons, however, inclined orbits are favorable. These leave a "polar
gap": an antipodal pair of axisymmetric polar caps without any data coverage,
typically smaller than 10 degrees in diameter for terrestrial gravitational
problems, but 20 degrees or more in some planetary magnetic configurations. The
estimation of spherical harmonic field coefficients from an incompletely
sampled sphere is prone to error, since the spherical harmonics are not
orthogonal over the partial domain of the cut sphere. Although approaches based
on wavelets have gained in popularity in the last decade, we present a method
for localized spherical analysis that is firmly rooted in spherical harmonics.
We construct a basis of bandlimited spherical functions that have the majority
of their energy concentrated in a subdomain of the unit sphere by solving
Slepian's (1960) concentration problem in spherical geometry, and use them for
the geodetic problem at hand. Most of this work has been published by us
elsewhere. Here, we highlight the connection of the "spherical Slepian basis"
to wavelets by showing their asymptotic self-similarity, and focus on the
computational considerations of calculating concentrated basis functions on
irregularly shaped domains.


title: Black Hole Formation in Fuzzy Sphere Collapse

abstract:
  We study the collapse of a fuzzy sphere, that is a spherical membrane built
out of D0-branes, in the BFSS model. At weak coupling, as the sphere shrinks,
open strings are produced. If the initial radius is large then open string
production is not important and the sphere behaves classically. At intermediate
initial radius the back-reaction from open string production is important but
the fuzzy sphere retains its identity. At small initial radius the sphere
collapses to form a black hole. The crossover between the later two regimes is
smooth and occurs at the correspondence point of Horowitz and Polchinski.


title: 3-color Bounded Patterned Self-assembly

abstract:
  Patterned self-assembly tile set synthesis PATS is the problem of finding a
minimal tile set which uniquely self-assembles into a given pattern. Czeizler
and Popa proved the NP-completeness of PATS and Seki showed that the PATS
problem is already NP-complete for patterns with 60 colors. In search for the
minimal number of colors such that PATS remains NP-complete, we introduce
multiple bound PATS (mbPATS) where we allow bounds for the numbers of tile
types of each color. We show that mbPATS is NP-complete for patterns with just
three colors and, as a byproduct of this result, we also obtain a novel proof
for the NP-completeness of PATS which is more concise than the previous proofs.