title:
Post-adiabatic Hamiltonian for low-energy excitations in a slowly
  time-dependent BCS-BEC crossover

abstract:
  We develop a Hamiltonian that describes the time-dependent formation of a
molecular Bose-Einstein condensate (BEC) from a Bardeen-Cooper-Schrieffer (BCS)
state of fermionic atoms as a result of slowly sweeping through a Feshbach
resonance. In contrast to many other calculations in the field (see e.g.
[1-4]), our Hamiltonian includes the leading post-adiabatic effects that arise
because the crossover proceeds at a non-zero sweep rate. We apply a path
integral approach and a stationary phase approximation for the molecular zero
momentum background, which is a good approximation for narrow resonances (see
e.g. [5, 6]). We use two-body adiabatic approximations to solve the atomic
evolution within this background. The dynamics of the non-zero momentum
molecular modes is solved within a dilute gas approximation and by mapping it
onto a purely bosonic Hamiltonian. Our main result is a post-adiabatic
effective Hamiltonian in terms of the instantaneous bosonic
(Anderson-)Bogoliubov modes, which holds throughout the whole resonance, as
long as the Feshbach sweep is slow enough to avoid breaking Cooper pairs.


title:
Algebras of distributions of binary semi-isolating formulas for families
  of isolated types and for countably categorical theories

abstract:
  We apply a general approach for distributions of binary isolating and
semi-isolating formulas to families of isolated types and to the class of
countably categorical theories.


title: Space-time symmetries and the Yang-Mills gradient flow

abstract:
  The recent introduction of the gradient flow has provided a new tool to probe
the dynamics of quantum field theories. The latest developments have shown how
to use the gradient flow for the exploration of symmetries, and the definition
of the corresponding renormalized Noether currents. In this paper we introduce
infinitesimal translations along the gradient flow for gauge theories, and
study the corresponding Ward identities. This approach is readily generalized
to the case of gauge theories defined on a lattice, where the regulator breaks
translation invariance. The Ward identities in this case lead to a
nonperturbative renormalization of the energy-momentum tensor. We discuss an
application of this method to the study of dilatations and scale invariance on
the lattice.


title:
Forcing of infinity and algebras of distributions of binary
  semi-isolating formulas for strongly minimal theories

abstract:
  We apply a general approach for distributions of binary isolating and
semi-isolating formulas to the class of strongly minimal theories.


title: Parameterizing dark sector perturbations via equations of state

abstract:
  The evolution of perturbations is a crucial part of the phenomenology of the
dark sector cosmology. We advocate parameterizing these perturbations using
equations of state for the entropy perturbation and the anisotropic stress. For
small perturbations, these equations of state will be linear in the density,
velocity and metric perturbations, and in principle these can be related back
to the field content of the underlying model allowing for confrontation with
observations. We illustrate our point by constructing gauge invariant entropy
perturbations for theories where the dark sector Lagrangian is a general
function of a scalar field, its first and second derivatives, and the metric
and its first derivative, ${\cal L}={\cal
L}(\phi,\partial_\mu\phi,\partial_\mu\partial_\nu\phi,g_{\mu\nu},\partial_{\alpha}g_{\mu\nu})$.
As an example, we show how to apply this approach to the case of models of
Kinetic Gravity Braiding.


title: Solar System constraints to nonminimally coupled gravity

abstract:
  We extend the analysis of Chiba, Smith and Erickcek \cite{CSE} of Solar
System constraints on $f(R)$ gravity to a class of nonminimally coupled (NMC)
theories of gravity. These generalize $f(R)$ theories by replacing the action
functional of General Relativity (GR) with a more general form involving two
functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$. While the
function $f^1(R)$ is a nonlinear term in the action, analogous to $f(R)$
gravity, the function $f^2(R)$ yields a NMC between the matter Lagrangian
density $\LL_m$ and the scalar curvature. The developed method allows for
obtaining constraints on the admissible classes of functions $f^1(R)$ and
$f^2(R)$, by requiring that predictions of NMC gravity are compatible with
Solar System tests of gravity. We apply this method to a NMC model which
accounts for the observed accelerated expansion of the Universe.


title:
Homogeneous spherically symmetric bodies with a nonminimal coupling
  between curvature and matter: the choice of the Lagrangian density for matter

abstract:
  In this work we study how a nonminimal coupling between matter and gravity
can modify the structure of a homogeneous spherical body. The physical
relevance of the adopted Lagrangian density is ascertained, with results
obtained for two different choices of the latter.


title:
Interaction of double sine-Gordon solitons with external potentials: an
  analytical model

abstract:
  Interaction of Double sine-Gordon solitons with a space dependent potential
wall and also a potential well has been investigated by employing an analytical
model based on the collective coordinate approach. The potential has been added
to the model through a suitable nontrivial metric for the background
space-time. The model is able to predict most of the features of the
soliton-potential interaction. It is shown that a soliton can pass through a
potential barrier if its velocity is greater than a critical velocity which is
a function of soliton initial conditions and also characters of the potential.
It is interesting that the solitons of the double sine-Gordon model can be
trapped by a potential barrier and oscillate there. This situation is very
important in applied physics. Soliton-well system has been investigated using
the presented model too. Analytical results also have been compared with the
results of the direct numerical solutions.


title:
Numerical solution of Dyson Brownian motion and a sampling scheme for
  invariant matrix ensembles

abstract:
  The Dyson Brownian Motion (DBM) describes the stochastic evolution of $N$
points on the line driven by an applied potential, a Coulombic repulsion and
identical, independent Brownian forcing at each point. We use an explicit tamed
Euler scheme to numerically solve the Dyson Brownian motion and sample the
equilibrium measure for non-quadratic potentials. The Coulomb repulsion is too
singular for the SDE to satisfy the hypotheses of rigorous convergence proofs
for tamed Euler schemes. Nevertheless, in practice the scheme is observed to be
stable for time steps of O(1/N^2) and to relax exponentially fast to the
equilibrium measure with a rate constant of O(1) independent of $N$. Further,
this convergence rate appears to improve with $N$ in accordance with O(1/N)
relaxation of local statistics of the Dyson Brownian motion. This allows us to
use the Dyson Brownian motion to sample $N\times N$ Hermitian matrices from the
invariant ensembles. The computational cost of generating $M$ independent
samples is O(MN^4) with a naive scheme, and O(MN^3\log N) when a fast multipole
method is used to evaluate the Coulomb interaction.


title:
Rationality of cycles on function field of exceptional projective
  homogeneous varieties

abstract:
  In this article we prove a result comparing rationality of algebraic cycles
over the function field of a projective homogeneous variety under a linear
algebraic group of type $F_4$ or $E_8$ and over the base field, which can be of
any characteristic.


title: Searching with and against the stream: Levy or Brown?

abstract:
  We study the efficiency of search processes based on Levy flights (LFs) with
power-law distributed jump lengths in the presence of an external drift. While
LFs turn out to be efficient search processes when relative to the starting
point the target is upstream, in the downstream scenario regular Brownian
motion turns out to be advantageous. This is caused by the occurrence of
leapovers of LFs, due to which LFs typically overshoot a point in space. We
establish criteria when the combination of the external stream and the initial
distance between the starting point and the target favors LFs over regular
Brownian search. Contrary to the common belief that LFs with a stable index
alpha=1 are optimal, we find that the optimal alpha may range in the entire
interval (1,2) and even include Brownian motion as the overall most efficient
search strategy.


title:
A Monte Carlo Method to Approximate Conditional Expectations based on a
  Theorem of Besicovitch: Application to Equivariant Estimation of the
  Parameters of the General Half-Normal Distribution

abstract:
  A natural Monte Carlo method to approximate conditional expectations in a
probabilistic framework is justified by a general result inspired on the
Besicovitch covering theorem on differentiation of measures. The method is
specially useful when densities are not available or are not easy to compute.
The method is illustrated by means of some examples and can also be used in a
statistical setting to approximate the conditional expectation given a
sufficient statistic, for instance. In fact, it is applied to evaluate the
minimum risk equivariant estimator (MRE) of the location parameter of a general
half-normal distribution since this estimator is described in terms of a
conditional expectation for known values of the location and scale parameters.
For the sake of completeness, an explicit expression of the the minimum risk
equivariant estimator of the scale parameter is given. For all we know, these
estimators have not been given before in the literature. Simulation studies are
realized to compare the behavior of these estimators with that of maximum
likelihood and unbiased estimators.


title: Hyperelliptic Schottky Problem and Stable Modular Forms

abstract:
  It is well known that, fixed an even, unimodular, positive definite quadratic
form, one can construct a modular form in each genus; this form is called the
theta series associated to the quadratic form. Varying the quadratic form, one
obtains the ring of stable modular forms. We show that the differences of theta
series associated to specific pairs of quadratic forms vanish on the locus of
hyperelliptic Jacobians in each genus. In our examples, the quadratic forms
have rank 24, 32 and 48. The proof relies on a geometric result about the
boundary of the Satake compactification of the hyperelliptic locus. We also
study the monoid formed by the moduli space of all principally polarised
abelian varieties, the operation being the product of abelian varieties. We use
this construction to show that the ideal of stable modular forms vanishing on
the hyperelliptic locus in each genus is generated by differences of theta
series.


title:
Propagation and Distribution of Quantum Correlations in a Cavity QED
  Network

abstract:
  We study the propagation and distribution of quantum correlations through two
chains of atoms inside cavities joined by optical fibers. We consider an
effective Hamiltonian for the system and cavity losses, in the dressed atom
picture, using the Generalized Master Equation.


title: Multiclass Total Variation Clustering

abstract:
  Ideas from the image processing literature have recently motivated a new set
of clustering algorithms that rely on the concept of total variation. While
these algorithms perform well for bi-partitioning tasks, their recursive
extensions yield unimpressive results for multiclass clustering tasks. This
paper presents a general framework for multiclass total variation clustering
that does not rely on recursion. The results greatly outperform previous total
variation algorithms and compare well with state-of-the-art NMF approaches.


title:
Dynamical mean-field theory for quantum spin systems: Test of solutions
  for magnetically ordered states

abstract:
  A spin version of dynamical mean-field theory is extended for magnetically
ordered states in the Heisenberg model. The self-consistency equations are
solved with high numerical accuracy by means of the continuous-time quantum
Monte Carlo with bosonic baths coupled to the spin. The resultant solution is
critically tested by known physical properties. In contrast with the mean-field
theory, soft paramagnons appear near the transition temperature. Moreover, the
Nambu-Goldstone mode (magnon) in the ferromagnetic phase is reproduced
reasonably well. However, antiferromagnetic magnons have an energy gap in
contradiction to the Nambu-Goldstone theorem. The origin of this failure is
discussed in connection with an artificial first-order nature of the
transition.


title: Decentralized Data Reduction with Quantization Constraints

abstract:
  A guiding principle for data reduction in statistical inference is the
sufficiency principle. This paper extends the classical sufficiency principle
to decentralized inference, i.e., data reduction needs to be achieved in a
decentralized manner. We examine the notions of local and global sufficient
statistics and the relationship between the two for decentralized inference
under different observation models. We then consider the impacts of
quantization on decentralized data reduction which is often needed when
communications among sensors are subject to finite capacity constraints. The
central question we intend to ask is: if each node in a decentralized inference
system has to summarize its data using a finite number of bits, is it still
optimal to implement data reduction using global sufficient statistics prior to
quantization? We show that the answer is negative using a simple example and
proceed to identify conditions under which sufficiency based data reduction
followed by quantization is indeed optimal. They include the well known case
when the data at decentralized nodes are conditionally independent as well as a
class of problems with conditionally dependent observations that admit
conditional independence structure through the introduction of an appropriately
chosen hidden variable.


title: Multiple valued functions and integral currents

abstract:
  We prove several results on Almgren's multiple valued functions and their
links to integral currents. In particular, we give a simple proof of the fact
that a Lipschitz multiple valued map naturally defines an integer rectifiable
current; we derive explicit formulae for the boundary, the mass and the first
variations along certain specific vector-fields; and exploit this connection to
derive a delicate reparametrization property for multiple valued functions.
These results play a crucial role in our new proof of the partial regularity of
area minimizing currents.


title:
Exponential convergence to equilibrium in cellular automata
  asymptotically emulating identity

abstract:
  We consider the problem of finding the density of 1's in a configuration
obtained by $n$ iterations of a given cellular automaton (CA) rule, starting
from disordered initial condition. While this problems is intractable in full
generality for a general CA rule, we argue that for some sufficiently simple
classes of rules it is possible to express the density in terms of elementary
functions. Rules asymptotically emulating identity are one example of such a
class, and density formulae have been previously obtained for several of them.
We show how to obtain formulae for density for two further rules in this class,
160 and 168, and postulate likely expression for density for eight other rules.
Our results are valid for arbitrary initial density. Finally, we conjecture
that the density of 1's for CA rules asymptotically emulating identity always
approaches the equilibrium point exponentially fast.


title: Chiral Ladders and the Edges of Chern Insulators

abstract:
  The realization and detection of topological phases with ultracold atomic
gases is at the frontier of current theoretical and experimental research.
Here, we identify cold atoms in optical ladders subjected to synthetic magnetic
fields as readily realizable bridges between one-dimensional spin-orbit (time
reversal) topological insulators and two-dimensional Chern insulators. We
reveal three instances of their promising potential: i) they realize spin-orbit
coupling, with the left-right leg degree of freedom playing the role of an
effective spin, ii) their energy bands and eigenstates exactly reproduce the
topological chiral edge modes of two-dimensional Chern insulators, and iii)
they can be tailored to realize a topological phase transition from a trivial
to a topological insulating phase. We propose realistic schemes to observe the
chiral and topological properties of ladder systems with current optical
lattice-based experiments. Our findings open a door to the exploration of the
physics of the edges of Chern insulators and to the realization of spin-orbit
coupling and topological superfluid phases with ultracold atomic gases.


title: Regularity of area minimizing currents II: center manifold

abstract:
  This is the second paper of a series of three on the regularity of higher
codimension area minimizing integral currents. Here we perform the second main
step in the analysis of the singularities, namely the construction of a center
manifold, i.e. an approximate average of the sheets of an almost flat area
minimizing current. Such center manifold is complemented with a Lipschitz
multi-valued map on its normal bundle, which approximates the current with a
highe degree of accuracy. In the third and final paper these objects are used
to conclude a new proof of Almgren's celebrated dimension bound on the singular
set.


title: Ferromagnetism and Ferroelectricity in epitaxial ultra-thin BiMnO3 films

abstract:
  We studied the ferroelectric and ferromagnetic properties of compressive
strained and unstrained BiMnO3 thin films grown by rf-magnetron sputtering.
BiMnO3 samples exhibit a 2D cube-on-cube growth mode and a pseudo-cubic
struc-ture up to a thickness of 15 nm and of 25 nm when deposited on (001)
SrTiO3 and (110) DyScO3, respectively. Above these thicknesses we observe a
switching to a 3D island growth and a simultaneous structural change to a
monoclinic structure characterized by a (00l) orientation of the monoclinic
unit cell. While ferromagnetism is observed below Tc = 100 K for all samples,
signatures of room temperature ferroelectricity were found only in the
pseudo-cubic ultra-thin films, indicating a correlation between electronic and
structural orders.


title:
Phenomenology of axial-vector and pseudovector mesons: decays and mixing
  in the kaonic sector

abstract:
  We study the decays of the lightest axial-vector and pseudovector mesons,
interpreted as quark-antiquark states, into a vector and a pseudoscalar meson.
We show that the quarkonium assignment delivers a good description of the
decays and allows also to make further testable predictions. In the kaonic
sector, the physical resonances $K_{1}(1270)$ and $K_{1}(1400)$ emerge as mixed
objects of an axial vector state $K_{1,A}$ and a pseudovector state $K_{1,B}$.
We determine the mixing angle as $\left\vert
\theta_{K}\right\vert=\left(33.6\pm4.3\right) ^{\circ}$, a value compatible
with previous studies but with a smaller uncertainty. This result may be
helpful for testing models beyond the Standard Model of particle physics in
which decays into the kaonic resonances $K_{1}(1270)$ and $K_{1}(1400)$ are
investigated.


title: Regularity of area minimizing currents III: blow-up

abstract:
  This is the last of a series of three papers in which we give a new, shorter
proof of a slightly improved version of Almgren's partial regularity of area
minimizing currents in Riemannian manifolds. Here we perform a blow-up analysis
deducing the regularity of area minimizing currents from that of Dir-minimizing
multiple valued functions.


title: Regularity of area minimizing currents I: gradient L^p estimates

abstract:
  In a series of papers, including the present one, we give a new, shorter
proof of Almgren's partial regularity theorem for area minimizing currents in a
Riemannian manifold, with a slight improvement on the regularity assumption for
the latter. This note establishes a new a priori estimate on the excess measure
of an area minimizing current, together with several statements concerning
approximations with Lipschitz multiple valued graphs. Our new a priori estimate
is an higher integrability type result, which has a counterpart in the theory
of Dir-minimizing multiple valued functions and plays a key role in estimating
the accuracy of the Lipschitz approximations.


title:
Method and Advantages of Genetic Algorithms in Parameterization of
  Interatomic Potentials: Metal-Oxides

abstract:
  The method and the advantages of an evolutionary computing based approach
using a steady state genetic algorithm (GA) for the parameterization of
interatomic potentials for metal oxides within the shell model framework are
developed and described. We show that the GA based methodology for the
parameterization of interatomic force field functions is capable of (a)
simultaneous optimization of the multiple phases or properties of a material in
a single run, (b) facilitates the incremental re-optimization of the whole
system as more data is available for either additional phases or material
properties not included in previous runs, and (c) successful global
optimization in the presence of multiple local minima in the parameter space.
As an example, we apply the method towards simultaneous optimization of four
distinct crystalline phases of Barium Titanate (BaTiO3 or BTO) using an ab
initio density functional theory (DFT) based reference dataset. We find that
the optimized force field function is capable of the prediction of the two
phases not used in the optimization procedure, and that many derived physical
properties such as the equilibrium lattice constants, unit cell volume, elastic
properties, coefficient of thermal expansion, and average electronic
polarization are in good agreement with the experimental results available from
the literature.


title:
Sublinear variance in first-passage percolation for general
  distributions

abstract:
  We prove that the variance of the passage time from the origin to a point x
in first-passage percolation on Z^d is sublinear in the distance to x when d
\geq 2, obeying the bound Cx/(log x), under minimal assumptions on the
edge-weight distribution. The proof applies equally to absolutely continuous,
discrete and singular continuous distributions and mixtures thereof, and
requires only 2+log moments. The main result extends work of
Benjamini-Kalai-Schramm and Benaim-Rossignol.


title: Timing of pulsars found in a deep Parkes multibeam survey

abstract:
  We have carried out a sensitive radio pulsar survey along the northern
Galactic plane ($50^{\circ} < l < 60^{\circ}$ and $|b| \lapp 2^{\circ}$) using
the Parkes 20-cm multibeam system. We observed each position for 70-min on two
separate epochs. Our analyses to date have so far resulted in the detection of
32 pulsars, of which 17 were previously unknown. Here we summarize the
observations and analysis and present the timing observations of 11 pulsars and
discovery parameters for a further 6 pulsars. We also present a timing solution
for the 166-ms bursting pulsar, PSR~J1938+2213, previously discovered during an
Arecibo drift-scan survey. Our survey data for this pulsar show that the
emission can be described by a steady pulse component with bursting emission,
which lasts for typically 20--25 pulse periods, superposed. Other new
discoveries are the young 80.1-ms pulsar PSR~J1935+2025 which exhibits a
significant amount of unmodeled low-frequency noise in its timing residuals,
and the 4.2-ms pulsar PSR~J1935+1726 which is in a low-mass binary system with
a 90.7-day circular orbit.


title: Magneto-optical conductivity in a topological insulator

abstract:
  Adding a small subdominant quadratic in momentum term to a dominant linear
Dirac dispersion curve affects conduction and valence band differently and
leads to an hourglass-like structure for energy as a function of momentum. This
applies to the protected surface states in topological insulators. The energies
of the conduction and valence band Landau levels are also different and this
leads to the splitting of optical absorption lines produced by the magnetic
field, which acquire a two peak structure. It also changes the peaks in the
imaginary part of the Hall conductivity into two distinct contributions of
opposite signs. The real part of the circularly polarized optical conductivity
however retains its single peak structure but the peaks in right and left
handedness case are shifted in energy with respect to each other in contrast to
the pure Dirac case. The magnitude of the semiclassical cyclotron frequency is
significantly modified by the presence of a mass term as is its variation with
value of the chemical potential $\mu$. Its optical spectral weight is found to
decrease with increasing $\mu$ rather than increase as it does in the pure
Dirac limit.


title:
A general theory of intertemporal decision-making and the perception of
  time

abstract:
  Animals and humans make decisions based on their expected outcomes. Since
relevant outcomes are often delayed, perceiving delays and choosing between
earlier versus later rewards (intertemporal decision-making) is an essential
component of animal behavior. The myriad observations made in experiments
studying intertemporal decision-making and time perception have not yet been
rationalized within a single theory. Here we present a
theory-Training--Integrated Maximized Estimation of Reinforcement Rate
(TIMERR)--that explains a wide variety of behavioral observations made in
intertemporal decision-making and the perception of time. Our theory postulates
that animals make intertemporal choices to optimize expected reward rates over
a limited temporal window; this window includes a past integration interval
(over which experienced reward rate is estimated) and the expected delay to
future reward. Using this theory, we derive a mathematical expression for the
subjective representation of time. A unique contribution of our work is in
finding that the past integration interval directly determines the steepness of
temporal discounting and the nonlinearity of time perception. In so doing, our
theory provides a single framework to understand both intertemporal
decision-making and time perception.


title: Renormalizable Models in Rank $d\geq 2$ Tensorial Group Field Theory

abstract:
  Classes of renormalizable models in the Tensorial Group Field Theory
framework are investigated. The rank $d$ tensor fields are defined over $d$
copies of a group manifold $G_D=U(1)^D$ or $G_D= SU(2)^D$ with no symmetry and
no gauge invariance assumed on the fields. In particular, we explore the space
of renormalizable models endowed with a kinetic term corresponding to a sum of
momenta of the form $p^{2a}$, $a\in ]0,1]$. This study is tailored for models
equipped with Laplacian dynamics on $G_D$ (case $a=1$) but also for more exotic
nonlocal models in quantum topology (case $0<a<1$). A generic model can be
written $(_{\dim G_D}\Phi^{k}_{d}, a)$, where $k$ is the maximal valence of its
interactions. Using a multi-scale analysis for the generic situation, we
identify several classes of renormalizable actions including matrix model
actions. In this specific instance, we find a tower of renormalizable matrix
models parametrized by $k\geq 4$. In a second part of this work, we focus on
the UV behavior of the models up to maximal valence of interaction $k =6$. All
rank $d\geq 3$ tensor models proved renormalizable are asymptotically free in
the UV. All matrix models with $k=4$ have a vanishing $\beta$-function at
one-loop and, very likely, reproduce the same feature of the Grosse-Wulkenhaar
model [Commun. Math. Phys. {\bf 256}, 305 (2004)].


title: A note on QUBO instances defined on Chimera graphs

abstract:
  McGeoch and Wang (2013) recently obtained optimal or near-optimal solutions
to some quadratic unconstrained boolean optimization (QUBO) problem instances
using a 439 qubit D-Wave Two quantum computing system in much less time than
with the IBM ILOG CPLEX mixed-integer quadratic programming (MIQP) solver. The
problems studied by McGeoch and Wang are defined on subgraphs -- with up to 439
nodes -- of Chimera graphs. We observe that after a standard reformulation of
the QUBO problem as a mixed-integer linear program (MILP), the specific
instances used by McGeoch and Wang can be solved to optimality with the CPLEX
MILP solver in much less time than the time reported in McGeoch and Wang for
the CPLEX MIQP solver. However, the solution time is still more than the time
taken by the D-Wave computer in the McGeoch-Wang tests.


title: The Brownian Mean Field model

abstract:
  We discuss the dynamics and thermodynamics of the Brownian Mean Field (BMF)
model which is a system of N Brownian particles moving on a circle and
interacting via a cosine potential. It can be viewed as the canonical version
of the Hamiltonian Mean Field (HMF) model. We first complete the description of
this system in the mean field approximation. Then, we take fluctuations into
account and study the stochastic evolution of the magnetization both in the
homogeneous phase and in the inhomogeneous phase. We discuss its behavior close
to the critical point.


title:
Nematic Phase in two-dimensional frustrated systems with power law
  decaying interactions

abstract:
  We address the problem of orientational order in frustrated interaction
systems as a function of the relative range of the competing interactions. We
study a spin model Hamiltonian with short range ferromagnetic interaction
competing with an antiferromagnetic component that decays as a power law of the
distance between spins, $1/r^\alpha$. These systems may develop a nematic phase
between the isotropic disordered and stripe phases. We evaluate the nematic
order parameter using a self-consistent mean field calculation. Our main result
indicates that the nematic phase exists, at mean-field level, provided
$0<\alpha<4$. We analytically compute the nematic critical temperature and show
that it increases with the range of the interaction, reaching its maximum near
$\alpha\sim 0.5$. We also compute a corse-grained effective Hamiltonian for
long wave-length fluctuations. For $0<\alpha<4$ the inverse susceptibility
develops a set of continuous minima at wave vectors $|\vec k|=k_0(\alpha)$
which dictate the long distance physics of the system. For $\alpha\to 4$,
$k_0\to 0$, making the competition between interactions ineffective for greater
values of $\alpha$.


title: Conformal supergravity in three dimensions: Off-shell actions

abstract:
  Using the off-shell formulation for N-extended conformal supergravity in
three dimensions, which has recently been presented in arXiv:1305.3132, we
construct superspace actions for conformal supergravity theories with N<6. For
each of the cases considered, we work out the complete component action as well
as the gauge transformation laws of the fields belonging to the Weyl
supermultiplet. The N=1 and N=2 component actions derived coincide with those
proposed by van Nieuwenhuizen and Rocek in the mid-1980s. The off-shell N=3,
N=4 and N=5 supergravity actions are new results. Upon elimination of the
auxiliary fields, these actions reduce to those constructed by Lindstrom and
Rocek in 1989 (and also by Gates and Nishino in 1993).


title: Coalescence, genetic diversity in sexual populations under selection

abstract:
  In sexual populations, selection operates neither on the whole genome, which
is repeatedly taken apart and reassembled by recombination, nor on individual
alleles that are tightly linked to the chromosomal neighborhood. The resulting
interference between linked alleles reduces the efficiency of selection and
distorts patterns of genetic diversity. Inference of evolutionary history from
diversity shaped by linked selection requires an understanding of these
patterns. Here, we present a simple but powerful scaling analysis identifying
the unit of selection as the genomic "linkage block" with a characteristic
length determined in a self-consistent manner by the condition that the rate of
recombination within the block is comparable to the fitness differences between
different alleles of the block. We find that an asexual model with the strength
of selection tuned to that of the linkage block provides an excellent
description of genetic diversity and the site frequency spectra when compared
to computer simulations. This linkage block approximation is accurate for the
entire spectrum of strength of selection and is particularly powerful in
scenarios with many weakly selected loci. The latter limit allows us to
characterize coalescence, genetic diversity, and the speed of adaptation in the
infinitesimal model of quantitative genetics.


title: Neuronal Alignment On Asymmetric Textured Surfaces

abstract:
  Axonal growth and the formation of synaptic connections are key steps in the
development of the nervous system. Here we present experimental and theoretical
results on axonal growth and interconnectivity in order to elucidate some of
the basic rules that neuronal cells use for functional connections with one
another. We demonstrate that a unidirectional nanotextured surface can bias
axonal growth. We perform a systematic investigation of neuronal processes on
asymmetric surfaces and quantify the role that biomechanical surface cues play
in neuronal growth. These results represent an important step towards
engineering directed axonal growth for neuro-regeneration studies.


title: Arc spaces of cA-type singularities

abstract:
  We study the space of arcs on a singularity of the form xy=f(z_1,..., z_n)
and prove 2 main results. (i) The number of irreducible components equals the
multiplicity of f minus 1. (ii) If n>1 and the leading homogeneous term of f is
not a perfect square then the Nash map from the set of irreducible components
to the set of essential divisors is not surjective.


title: Isotone extension of mappings

abstract:
  A set of necessary and sufficient conditions under which an isotone mapping
from a subset of a poset X to a poset Y has an extension to an isotone mapping
from X to Y are found.


title:
An Alternative Between Non-unique and Negative Yamabe Solutions to the
  Conformal Formulation of the Einstein Constraint Equations

abstract:
  The conformal method has been effective for parametrizing solutions to the
Einstein constraint equations on closed 3-manifolds. However, it is still not
well-understood; for example, existence of solutions to the conformal equations
for zero or negative Yamabe metrics is still unknown without the so-called
``CMC'' or ``near-CMC'' assumptions. The first existence results without such
assumptions, termed the ``far-from-CMC'' case, were obtained by Holst, Nagy,
and Tsogtgerel in 2008 for positive Yamabe metrics. However, their results are
based on topological arguments, and as a result solution uniqueness is not
known. Indeed, Maxwell gave evidence in 2011 that far-from-CMC solutions are
not unique in certain cases. In this article, we provide further insight by
establishing a type of alternative theorem for general far-from-CMC solutions.
For a given manifold M that admits a metric of positive scalar curvature and
scalar flat metric g(0) with no conformal Killing fields, we first prove
existence of an analytic, one-parameter family of metrics g(z) through g(0)
such that R(g(z)) = z. Using this family of metrics and given data
(tau,sigma,rho,j), we form a one-parameter family of operators F((phi,w),z)
whose zeros satisfy the conformal equations. Applying Liapnuov-Schmidt
reduction, we determine an analytic solution curve for F((phi,w),z) = 0 through
a critical point where the linearization of F((phi,w),z) vanishes. The
regularity of this curve, the definition of F((phi,w),z), and the earlier
far-from-CMC results of Holst et al. allow us to then prove the following
alternative theorem for far-from-CMC solutions: either (1) there exists a z_1
>0 such that (positive Yamabe) solutions to the z_1-parameterized conformal
equations are non-unique; or (2) there exists z_2 < 0 such that (negative
Yamabe) solutions to the z_2-parameterized conformal equations exist.


title:
Existence of solution for a class of nonlocal elliptic problem via
  sub-supersolution method

abstract:
  We show the existence of solution for some classes of nonlocal problems. Our
proof combines the presence of sub and supersolution with the pseudomonotone
operators theory.


title: Single- and multi-mode Fabry-P\'erot interference in suspended graphene

abstract:
  Phase coherence of charge carriers leads to electron-wave interference in
ballistic mesoscopic conductors. In graphene, such Fabry-P\'erot-like
interference has been observed, but a detailed analysis has been complicated by
the two-dimensional nature of conduction, which allows for complex interference
patterns. In this work, we have achieved high-quality Fabry-P\'erot
interference in a suspended graphene device, both in conductance and in shot
noise, and analyzed their structure using Fourier transform techniques. The
Fourier analysis reveals two sets of overlapping, coexisting interferences,
with the ratios of the diamonds being equal to the width to length ratio of the
device. We attribute these sets to a unique coexistence of longitudinal and
transverse resonances, with the longitudinal resonances originating from the
bunching of modes with low transverse momentum. Furthermore, our results give
insight into the renormalization of the Fermi velocity in suspended graphene
samples, caused by unscreened many-body interactions.


title:
Reservoir model for two-dimensional electron gases in quantizing
  magnetic fields: a review

abstract:
  We collect and review works which treat two-dimensional electron gases in
quantum wells (mostly GaAs/GaAlAs heterostructures) in the presence of
quantizing magnetic fields as open systems in contact with outside reservoirs.
If a reservoir is sufficiently large, it pins the Fermi level to a certain
energy. As a result, in a varying external magnetic field, the thermodynamic
equilibrium will force oscillations of the electron density in and out of the
quantum well (QW). This leads to a number of physical phenomena in
magneto-transport, interband and intraband magneto-optics, magnetization,
magneto-plasma dispersion, etc. In particular, as first proposed by Baraff and
Tsui, the density oscillations in and out of QW lead to plateaus in the Integer
Quantum Hall Effect (IQHE) at values observed in experiments. The gathered
evidence, especially from magneto-optical investigations, allows us to conclude
that, indeed, in most GaAs/GaAlAs hetrostructures one deals with open systems
in which the electron density in QWs oscillates as the magnetic field varies.
Relation of the density oscillations to other factors, such as electron
localization, and their combined influence on the quantum transport in 2D
electron gases, is discussed. In particular, a validity of the classical
formula for the Hall resistivity {\rho}xy = B/Nec is considered. It is
concluded that the density oscillations are not sufficient to be regarded as
the only source of plateaus in IQHE, although such claims have been sometimes
made in the past and present. Still, our general conclusion is that the
reservoir approach should be included in various descriptions of 2D electron
gases in the present of a magnetic field. An attempt has been made to quote all
the relevant literature on the subject.


title:
Determination of all pure quantum states from a minimal number of
  observables

abstract:
  We show that for any positive integer $n$, the maps $x \in \mathbb{C}^n
\mapsto \{\left|\langle x, z_i \rangle \right|^2\}_{i=1}^{4n} \in
\mathbb{R}^{4n}$, where $z_i$ are the columns of four $n\times n$ unitary
matrices, are generically injective modulo multiplication by a global phase
factor, yielding a family of embeddings of $\mathbb{C}P^{n-1}$ into
$\mathbb{R}^{4n-4}$. In particular, this implies that distribution measurements
about a pure state with four generic full-rank observables are informationally
complete, which is sharp for $n \geq 6$. To complement this
information-theoretic study, we establish in a companion paper that the
PhaseLift algorithm yields efficient phase retrieval from quadratic
measurements with $O(1)$ unitary matrices, with high probability, where the
unitaries are iid according to Haar measure.

categories: math-ph math.AG math.DG math.MP quant-ph


title:
Interference limits resolution of selection pressures from linked
  neutral diversity

abstract:
  Pervasive natural selection can strongly influence observed patterns of
genetic variation, but these effects remain poorly understood when multiple
selected variants segregate in nearby regions of the genome. Classical
population genetics fails to account for interference between linked mutations,
which grows increasingly severe as the density of selected polymorphisms
increases. Here, we describe a simple limit that emerges when interference is
common, in which the fitness effects of individual mutations play a relatively
minor role. Instead, molecular evolution is determined by the variance in
fitness within the population, defined over an effectively asexual segment of
the genome (a ``linkage block''). We exploit this insensitivity in a new
``coarse-grained'' coalescent framework, which approximates the effects of many
weakly selected mutations with a smaller number of strongly selected mutations
with the same variance in fitness. This approximation generates accurate and
efficient predictions for the genetic diversity that cannot be summarized by a
simple reduction in effective population size. However, these results suggest a
fundamental limit on our ability to resolve individual selection pressures from
contemporary sequence data alone, since a wide range of parameters yield nearly
identical patterns of sequence variability.


title: Luminous Satellites versus Dark Subhaloes: Clustering in the Milky Way

abstract:
  The observed population of the Milky Way satellite galaxies offer a unique
testing ground for galaxy formation theory on small-scales. Our novel approach
was to investigate the clustering of the known Milky Way satellite galaxies and
to quantify the amount of substructure within their distribution using a
two-point correlation function statistic in each of three spaces: configuration
space, line-of-sight velocity space, and four-dimensional phase-space. These
results were compared to those for three sets of subhaloes in the Via Lactea II
Cold Dark Matter simulation defined to represent the luminous dwarfs. We found
no evidence at a significance level above 2-sigma of substructure within the
distribution of the Milky Way satellite galaxies in any of the three spaces.
The "luminous" subhalo sets are more strongly clustered than are the Milky Way
satellites in all three spaces and over a broader range of scales in
four-dimensional phase-space. Each of the "luminous" subhalo sets are clustered
as a result of substructure within their line-of-sight velocity space
distributions at greater than 3-sigma significance, whereas the Milky Way
satellite galaxies are randomly distributed in line-of-sight velocity space.
While our comparison is with only one Cold Dark Matter simulation, the
inconsistencies between the Milky Way satellite galaxies and the Via Lactea II
subhalo sets for all clustering methods suggest a potential new 'small-scale'
tension between Cold Dark Matter theory and the observed Milky Way satellites.
Future work will obtain a more robust comparison between the observed Milky Way
satellites and Cold Dark Matter theory by studying additional simulations.


title: Flux calibration of the Herschel-SPIRE photometer

abstract:
  We describe the procedure used to flux calibrate the three-band submillimetre
photometer in the Spectral and Photometric Imaging REceiver (SPIRE) instrument
on the Herschel Space Observatory. This includes the equations describing the
calibration scheme, a justification for using Neptune as the primary
calibration source, a description of the observations and data processing
procedures used to derive flux calibration parameters (for converting from
voltage to flux density) for every bolometer in each array, an analysis of the
error budget in the flux calibration for the individual bolometers, and tests
of the flux calibration on observations of primary and secondary calibrators.
The procedure for deriving the flux calibration parameters is divided into two
parts. In the first part, we use observations of astronomical sources in
conjunction with the operation of the photometer internal calibration source to
derive the unscaled derivatives of the flux calibration curves. To scale the
calibration curves in Jy/beam/V, we then use observations of Neptune in which
the beam of each bolometer is mapped using Neptune observed in a very fine scan
pattern. The total instrumental uncertainties in the flux calibration for the
individual bolometers is ~0.5% for most bolometers, although a few bolometers
have uncertainties of ~1-5% because of issues with the Neptune observations.
Based on application of the flux calibration parameters to Neptune observations
performed using typical scan map observing modes, we determined that
measurements from each array as a whole have instrumental uncertainties of
1.5%. This is considerably less than the absolute calibration uncertainty
associated with the model of Neptune, which is estimated at 4%.


title:
Measurement of the earthshine polarization in the B, V, R, and I band as
  function of phase

abstract:
  The characterization of the polarimetric properties of the planet Earth is
important for the interpretation of expected observations and the planning of
future instruments. We present a multi-wavelengths and multi-phase set of
benchmark values for the polarization signal of the integrated light from the
planet Earth derived from new polarimetric observations of the earthshine
back-scattered from the Moon's dark side. Using a new, specially designed wide
field polarimeter we measured the fractional polarization of the earthshine in
the B, V, R and I filters for Earth phase angles alpha between 30{\deg} and
110{\deg}. The phase dependence of the earthshine polarization is fitted by a
function p x sin(alpha)^2. To determine the polarization of the planet Earth we
correct our earthshine measurements by a polarization efficiency function for
the lunar surface derived from measurements of lunar samples from the
literature. The polarization of the earthshine decreases towards longer
wavelengths and is about a factor 1.3 lower for the higher albedo highlands.
For mare regions the measured maximum polarization is about 13 % at quadrature
in the B band. The resulting fractional polarizations for Earth are 24.6 % for
the B band, 19.1 % for the V band, 13.5 % for the R band, and 8.3 % for the I
band. Together with literature values for the spectral reflectivity of Earth we
obtain a contrast between the polarized flux of the Earth and the (total) flux
of the Sun with an uncertainty of less than 20 % and we find that the best
phase to detect an Earth twin is around an Earth phase alpha=65{\deg}. The
polarimetric models of Earth-like planets from Stam (2008) are in qualitative
agreement with our results but there are also significant differences which
might guide more detailed computations.


title: The probability that a character value is zero for the symmetric group

abstract:
  We consider random character values X(g) of the symmetric group on n symbols,
where X is chosen at random from the set of irreducible characters and g is
chosen at random from the group, and we show that X(g)=0 with probability
tending to one as n tends to infinity.


title:
Global in Time Estimates for the Spatially Homogeneous Landau Equation
  with Soft Potentials

abstract:
  This paper deals with some global in time a priori estimates of the spatially
homogeneous Landau equation for soft potentials $\ga\in[-2,0)$. For the first
result, we obtain the estimate of weak solutions in
$L^{\alpha}_{t}L_{v}^{3-\eps}$ for $\alpha=\frac{2(3-\eps)}{3(2-\eps)}$ and
$0<\eps<1$, which is an improvement over estimates by Fournier-Guerin [N.
Fournier; H. Guerin, Well-posedness of the spatially homogeneous Landau
equation for soft potentials. J. Funct. Anal. 25(2009), no. 8, 2542--2560]. Foe
the second result, we have the estimate of weak solutions in
$L_{t}^{\infty}L^{p}_{v}$, $p>1$, which extends part of results by
Fournier-Guerin and Alexandre-Liao-Lin [R. Alexandre, J. Liao, and C. Lin, Some
a priori estimates for the homogeneous Landau equation with soft potentials,
arXiv:1302.1814]. As an application, we deduce some global well-posedness
results for $\ga\in [-2,0)$. Our estimates include the critical case $\ga=-2$,
which is the key point in this paper.


title: Josephson Effect in Coherent Roton Aggregates

abstract:
  A microwave electromagnetic field can excite a coherent roton aggregate in
liquid helium around a dielectric resonator. We show that multiple coherent
aggregates are excited simultaneously and predict a Josephson effect between
them. The superfluid velocity acts as a "voltage across the weak link" in
superconducting Josephson junctions. A comparison with existing experimental
data is made.


title: Birational invariance in logarithmic Gromov-Witten theory

abstract:
  Gromov-Witten invariants have been constructed to be deformation invariant,
but their behavior under other transformations is subtle. In this note we show
that logarithmic Gromov-Witten invariants are also invariant under
appropriately defined logarithmic modifications.


title:
Redundant operators in the exact renormalisation group and in the f(R)
  approximation to asymptotic safety

abstract:
  In this paper we review the definition and properties of redundant operators
in the exact renormalisation group. We explain why it is important to require
them to be eigenoperators and why generically they appear only as a consequence
of symmetries of the particular choice of renormalisation group equations. This
clarifies when Newton's constant and or the cosmological constant can be
considered inessential. We then apply these ideas to the Local Potential
Approximation and approximations of a similar spirit such as the f(R)
approximation in the asymptotic safety programme in quantum gravity. We show
that these approximations can break down if the fixed point does not support a
`vacuum' solution in the appropriate domain: all eigenoperators become
redundant and the physical space of perturbations collapses to a point. We show
that this is the case for the recently discovered lines of fixed points in the
f(R) flow equations.


title: On polynomials connected to powers of Bessel functions

abstract:
  The series expansion of a power of the modified Bessel function of the first
kind is studied. This expansion involves a family of polynomials introduced by
C. Bender et al. New results on these polynomials established here include
recurrences in terms of Bell polynomials evaluated at values of the Bessel zeta
function. A probabilistic version of an identity of Euler yields additional
recurrences. Connections to the umbral formalism on Bessel functions introduced
by Cholewinski are established.


title:
Initial value problem for the linearized mean field Kramers equation
  with long-range interactions

abstract:
  We solve the initial value problem for the linearized mean field Kramers
equation describing Brownian particles with long-range interactions in the
$N\rightarrow +\infty$ limit. We show that the dielectric function can be
expressed in terms of incomplete Gamma functions. The dielectric functions
associated with the linearized Vlasov equation and with the linearized mean
field Smoluchowski equation are recovered as special cases corresponding to the
no friction limit or to the strong friction limit respectively. Although the
stability of the Maxwell-Boltzmann distribution is independent on the friction
parameter, the evolution of the perturbation depends on it in a non-trivial
manner. For illustration, we apply our results to self-gravitating systems,
plasmas, and to the attractive and repulsive BMF models.


title: A Dynamical Signature of Multiple Stellar Populations in 47 Tucanae

abstract:
  Based on the width of its main sequence, and an actual observed split when
viewed through particular filters, it is widely accepted that 47 Tucanae
contains multiple stellar populations. In this contribution, we divide the
main-sequence of 47 Tuc into four color groups, which presumably represent
stars of various chemical compositions. The kinematic properties of each of
these groups is explored via proper-motions, and a strong signal emerges of
differing proper-motion anisotropies with differing main-sequence color; the
bluest main-sequence stars exhibit the largest proper-motion anisotropy which
becomes undetectable for the reddest stars. In addition, the bluest stars are
also the most centrally concentrated. A simiilar analysis for SMC stars, which
are located in the background of 47 Tuc on our frames, yields none of the
anisotropy exhibited by the 47 Tuc stars. We discuss implications of these
results for possible formation scenarios of the various populations.


title:
A correlation between star formation rate and average black hole
  accretion in star forming galaxies

abstract:
  We present a measurement of the average supermassive black hole accretion
rate (BHAR) as a function of star formation rate (SFR) for galaxies in the
redshift range 0.25<z<0.8. We study a sample of 1,767 far-IR selected
star-forming galaxies in the 9 deg^2 Bo\"otes multiwavelength survey field. The
SFR is estimated using 250 micron observations from the Herschel Space
Observatory, for which the contribution from the AGN is minimal. In this
sample, 121 AGNs are directly identified using X-ray or mid-IR selection
criteria. We combined these detected AGNs and an X-ray stacking analysis for
undetected sources to study the average BHAR for all of the star-forming
galaxies in our sample. We find an almost linear relation between the average
BHAR (in M_sun/year) and the SFR (in M_sun/year) for galaxies across a wide SFR
range 0.85<log SFR<2.56 : log BHAR=(-3.72\pm0.52)+(1.05\pm0.33) log SFR. This
global correlation between SFR and average BHAR is consistent with a simple
picture in which SFR and AGN activity are tightly linked over galaxy evolution
timescales.


title: The Pulsation Mode and Distance of the Cepheid FF Aquilae

abstract:
  The determination of pulsation mode and distance for field Cepheids is a
complicated problem best resolved by a luminosity estimate. For illustration a
technique based on spectroscopic luminosity discrimination is applied to the
4.47d s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable
yield values of <Mv>=-3.40+-0.02 s.e.(+-0.04 s.d.), average effective
temperature Teff=6195+-24 K, and intrinsic color (<B>-<V>)o = +0.506+-0.007,
corresponding to a reddening of E(B-V)=0.25+-0.01, or E(B-V)(B0)=0.26+-0.01.
The skewed light curve, intrinsic color, and luminosity of FF Aql are
consistent with fundamental mode pulsation for a small amplitude classical
Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A
distance of 413+-14 pc is estimated from the Cepheid's angular diameter in
conjunction with a mean radius of <R>=39.0+-0.7 Rsun inferred from its
luminosity and effective temperature. The dust extinction towards FF Aql is
described by a ratio of total-to-selective extinction of
Rv=Av/E(B-V)=3.16+-0.34 according to the star's apparent distance modulus.


title:
The mmax-Mecl relation, the IMF and IGIMF: probabilistically sampled
  functions?

abstract:
  We introduce a new method to measure the dispersion of mmax values of star
clusters and show that the observed sample of mmax is inconsistent with random
sampling from an universal stellar initial mass function (IMF) at a 99.9%
confidence level. The scatter seen in the mmax-Mecl data can be mainly (76%)
understood as being the result of observational uncertainties only. The scatter
of mmax values at a given Mecl are consistent with mostly measurement
uncertainties such that the true (physical) scatter may be very small.
Additionally, new data on the local star-formation regions Taurus-Auriga and
L1641 in Orion make stochastically formed stellar populations rather unlikely.
The data are however consistent with the local IGIMF (integrated galactic
stellar initial mass function) theory according to which a stellar population
is a sum of individual star-forming events each of which is described by well
defined physical laws. Randomly sampled IMFs and henceforth scale-free star
formation seems to be in contradiction to observed reality.


title: Optimal non-linear transformations for large scale structure statistics

abstract:
  Recently, several studies proposed non-linear transformations, such as a
logarithmic or Gaussianization transformation, as efficient tools to recapture
information about the (Gaussian) initial conditions. During non-linear
evolution, part of the cosmologically relevant information leaks out from the
second moment of the distribution. This information is accessible only through
complex higher order moments or, in the worst case, becomes inaccessible to the
hierarchy. The focus of this work is to investigate these transformations in
the framework of Fisher information using cosmological perturbation theory of
the matter field with Gaussian initial conditions. We show that at each order
in perturbation theory, there is a polynomial of corresponding order exhausting
the information on a given parameter. This polynomial can be interpreted as the
Taylor expansion of the maximally efficient "sufficient" observable in the
non-linear regime. We determine explicitly this maximally efficient observable
for local transformations. Remarkably, this optimal transform is essentially
the simple power transform with an exponent related to the slope of the power
spectrum; when this is -1, it is indistinguishable from the logarithmic
transform. This transform Gaussianizes the distribution, and recovers the
linear density contrast. Thus a direct connection is revealed between undoing
of the non-linear dynamics and the efficient capture of Fisher information. Our
analytical results were compared with measurements from the Millennium
Simulation density field. We found that our transforms remain very close to
optimal even in the deeply non-linear regime with \sigma^2 \sim 10.


title: Dynamical structure factor of triangular-lattice antiferromagnet

abstract:
  We elucidate the role of magnon interaction and spontaneous decays in the
spin dynamics of the triangular-lattice Heisenberg antiferromagnet by
calculating its dynamical structure factor within the spin-wave theory.
Explicit theoretical results for neutron-scattering intensity are provided for
spins S=1/2 and S=3/2. The dynamical structure factor exhibits unconventional
features such as quasiparticle peaks broadened by decays, non-Lorentzian
lineshapes, and significant spectral weight redistribution to the two-magnon
continuum. This rich excitation spectrum illustrates the complexity of the
triangular-lattice antiferromagnet and provides distinctive qualitative and
quantitative fingerprints for experimental observation of decay-induced magnon
dynamics.


title:
Constraints on Spatial Variations in the Fine-Structure constant from
  Planck

abstract:
  We use the Cosmic Microwave Background (CMB) anisotropy data from Planck to
constrain the spatial fluctuations of the fine-structure constant \alpha.
Through Thompson scattering of CMB photons, spatial anisotropies of \alpha lead
to higher-order correlations in the CMB anisotropies. We use a quadratic
estimator based on the four-point correlation function of the CMB temperature
anisotropy to extract the angular power spectrum of the spatial variation of
the fine-structure constant projected along the line of sight at the last
scattering surface. At tens of degree angular scales and above, we constrain
the rms fluctuations of the fine structure constant to be \delta
\alpha/\alpha_0= (1.34 +/- 5.82) x 10^-2 at the 95% confidence level with
respect to the standard value \alpha_0. We find no evidence for a spatially
varying \alpha at a redshift of 10^3.


title:
The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets
  around Young B and A Stars

abstract:
  We have carried out high contrast imaging of 70 young, nearby B and A stars
to search for brown dwarf and planetary companions as part of the Gemini NICI
Planet-Finding Campaign. Our survey represents the largest, deepest survey for
planets around high-mass stars (~1.5-2.5 M_sun) conducted to date and includes
the planet hosts beta Pic and Fomalhaut. We obtained follow-up astrometry of
all candidate companions within 400 AU projected separation for stars in
uncrowded fields and identified new low-mass companions to HD 1160 and HIP
79797. We have found that the previously known young brown dwarf companion to
HIP 79797 is itself a tight (3 AU) binary, composed of brown dwarfs with masses
58 (+21, -20) M_Jup and 55 (+20, -19) M_Jup, making this system one of the rare
substellar binaries in orbit around a star. Considering the contrast limits of
our NICI data and the fact that we did not detect any planets, we use
high-fidelity Monte Carlo simulations to show that fewer than 20% of 2 M_sun
stars can have giant planets greater than 4 M_Jup between 59 and 460 AU at 95%
confidence, and fewer than 10% of these stars can have a planet more massive
than 10 M_Jup between 38 and 650 AU. Overall, we find that large-separation
giant planets are not common around B and A stars: fewer than 10% of B and A
stars can have an analog to the HR 8799 b (7 M_Jup, 68 AU) planet at 95%
confidence. We also describe a new Bayesian technique for determining the ages
of field B and A stars from photometry and theoretical isochrones. Our method
produces more plausible ages for high-mass stars than previous age-dating
techniques, which tend to underestimate stellar ages and their uncertainties.


title:
Probing the chiral anomaly with nonlocal transport in three dimensional
  topological semimetals

abstract:
  Weyl semimetals are three-dimensional crystalline systems where pairs of
bands touch at points in momentum space, termed Weyl nodes, that are
characterized by a definite topological charge: the chirality. Consequently,
they exhibit the Adler-Bell-Jackiw anomaly, which in this condensed matter
realization implies that application of parallel electric ($\mathbf{E}$) and
magnetic ($\mathbf{B}$) fields pumps electrons between nodes of opposite
chirality at a rate proportional to $\mathbf{E}\cdot\mathbf{B}$. We argue that
this pumping is measurable via nonlocal transport experiments, in the limit of
weak internode scattering. Specifically, we show that as a consequence of the
anomaly, applying a local magnetic field parallel to an injected current
induces a valley imbalance that diffuses over long distances. A probe magnetic
field can then convert this imbalance into a measurable voltage drop far from
source and drain. Such nonlocal transport vanishes when the injected current
and magnetic field are orthogonal, and therefore serves as a test of the chiral
anomaly. We further demonstrate that a similar effect should also characterize
Dirac semimetals --- recently reported to have been observed in experiments ---
where a pair of Weyl nodes coexisting at a single point in the Brillouin zone
are protected by a crystal symmetry. Since the nodes are analogous to valley
degrees of freedom in semiconductors, this suggests that valley currents in
three dimensional topological semimetals can be controlled using electric
fields, which has potential practical `valleytronic' applications.


title:
Density behavior of spatial birth-and-death stochastic evolution of
  mutating genotypes under selection rates

abstract:
  We consider birth-and-death stochastic evolution of genotypes with different
lengths. The genotypes might mutate that provides a stochastic changing of
lengthes by a free diffusion law. The birth and death rates are length
dependent which corresponds to a selection effect. We study an asymptotic
behavior of a density for an infinite collection of genotypes. The cases of
space homogeneous and space heterogeneous densities are considered.


title: Characterization of the Red Giant HR 2582 Using the CHARA Array

abstract:
  We present the fundamental parameters of HR 2582, a high-mass red giant star
whose evolutionary state is a mystery. We used the CHARA Array interferometer
to directly measure the star's limb-darkened angular diameter (1.006+/-0.020
mas) and combined our measurement with parallax and photometry from the
literature to calculate its physical radius (35.76+/-5.31 R_Sun), luminosity
(517.8+/-17.5 L_Sun), bolometric flux (14.8+/-0.5 e-8 erg s-1 cm-2) and
effective temperature (4577+/-60 K). We then determined the star's mass
(5.6+/-1.7 M_Sun) using our new values with stellar oscillation results from
Baudin et al. Finally, using the Yonsei-Yale evolutionary models, we estimated
HR 2582's age to be 165 +20/-15 Myr. While our measurements do not provide the
precision required to definitively state where the star is in its evolution, it
remains an excellent test case for evaluating stellar interior models.


title:
Extended No-Scale Structure and $\alpha^{'2}$ Corrections to the Type
  IIB Action

abstract:
  We analyse a new ${\cal N}=1$ string tree level correction at ${\cal
O}(\alpha'^2)$ to the K\"ahler potential of the volume moduli of type IIB
Calabi-Yau flux compactification found recently by Grimm, Savelli and
Weissenbacher~\cite{Grimm:2013gma} and its impact on the moduli potential. We
find that it imposes a strong lower bound the Calabi-Yau volume in the Large
Volume Scenario of moduli stabilisation. For KKLT-like scenarios we find that
consistency of the action imposes an upper bound on the flux superpotential
$|W_0|\lesssim 10^{-3}$, while parametrically controlled survival of the KKLT
minimum needs extreme tuning of $W_0$ close to zero. We also analyse the
K\"ahler uplifting mechanism showing that it can operate on Calabi-Yau
manifolds where the new correction is present and dominated by the 4-cycle
controlling the overall volume if the volume is stabilised at values
$\mathcal{V} \gtrsim 10^3$. We discuss the phenomenological implication of
these bounds on $\mathcal{V}$ in the various scenarios.


title:
New Image Statistics for Detecting Disturbed Galaxy Morphologies at High
  Redshift

abstract:
  Testing theories of hierarchical structure formation requires estimating the
distribution of galaxy morphologies and its change with redshift. One aspect of
this investigation involves identifying galaxies with disturbed morphologies
(e.g., merging galaxies). This is often done by summarizing galaxy images
using, e.g., the CAS and Gini-M20 statistics of Conselice (2003) and Lotz et
al. (2004), respectively, and associating particular statistic values with
disturbance. We introduce three statistics that enhance detection of disturbed
morphologies at high-redshift (z ~ 2): the multi-mode (M), intensity (I), and
deviation (D) statistics. We show their effectiveness by training a
machine-learning classifier, random forest, using 1,639 galaxies observed in
the H band by the Hubble Space Telescope WFC3, galaxies that had been
previously classified by eye by the CANDELS collaboration (Grogin et al. 2011,
Koekemoer et al. 2011). We find that the MID statistics (and the A statistic of
Conselice 2003) are the most useful for identifying disturbed morphologies.
  We also explore whether human annotators are useful for identifying disturbed
morphologies. We demonstrate that they show limited ability to detect
disturbance at high redshift, and that increasing their number beyond
approximately 10 does not provably yield better classification performance. We
propose a simulation-based model-fitting algorithm that mitigates these issues
by bypassing annotation.


title: Self-energies on deformed spacetimes

abstract:
  We study one-loop photon (Pi) and neutrino (Sigma) self-energies in a U(1)
covariant gauge-theory on d-dimensional noncommutative spaces determined by a
antisymmetric-constant tensor theta^{mu nu}. For the general fermion-photon
(S_f) and photon self-interaction (S_g) the closed form results reveal
self-energies besetting with all kind of pathological terms: the UV divergence,
the quadratic UV/IR mixing terms as well as a logarithmic IR divergent term of
the type ln(mu^2(theta p)^2). In addition, the photon-loop produces new tensor
structures satisfying transversality condition by themselves. We show that the
photon self-energy in four-dimensional Euclidean spacetime can be reduced to
two finite terms by imposing a specific full rank of theta^{mu nu} and setting
deformation parameters (kappa_f,kappa_g)=(0,3). In this case the neutrino
two-point function vanishes. Thus for a specific point (0,3) in the
parameter-space (kappa_f,kappa_g), a covariant theta-exact approach is able to
produce a divergence-free result for one-loop quantum corrections, having also
well-defined both the commutative limit as well as the pointlike limit of an
extended object. While in two-dimensional space the photon self-energy is
finite for arbitrary (kappa_f,kappa_g) combinations, the neutrino self-energy
still contains an superficial IR divergence.


title: More on gapped Goldstones at finite density: More gapped Goldstones

abstract:
  It was recently argued that certain relativistic theories at finite density
can exhibit an unconventional spectrum of Goldstone excitations, with gapped
Goldstones whose gap is exactly calculable in terms of the symmetry algebra. We
confirm this result as well as previous ones concerning gapless Goldstones for
non-relativistic systems via a coset construction of the low-energy effective
field theory. Moreover, our analysis unveils additional gapped Goldstones,
naturally as light as the others, but this time with a model-dependent gap.
Their exact number cannot be inferred solely from the symmetry breaking pattern
either, but rather depends on the details of the symmetry breaking mechanism--a
statement that we explicitly verify with a number of examples. Along the way we
provide what we believe to be a particularly transparent interpretation of the
so-called inverse-Higgs constraints for spontaneously broken spacetime
symmetries.


title: Metal jumps across sloshing cold fronts: the case of A496

abstract:
  Cold-fronts in cool-core clusters are thought to be induced by minor mergers
and to develop through a sloshing mechanism. While temperature and
surface-brightness jumps have been detected and measured in many systems, a
detailed characterization of the metal abundance across the discontinuity is
only available for a handful of objects. Within the sloshing scenario, we
expect the central cool and metal rich gas to be displaced outwards into lower
abundance regions, thus generating a metal discontinuity across the front. We
analyzed a long (120 ksec) XMM-Newton observation of A496 to study the metal
distribution and its correlation with the cold-fronts. We find Fe
discontinuities across the two main cold-fronts located ~60 kpc NNW and ~160
kpc South of the peak and a metal excess in the South direction.


title: On the sign of regular algebraic polarizable automorphic representations

abstract:
  We remove a parity condition from the construction of automorphic Galois
representations carried out in the Paris Book Project. We subsequently
generalize this construction to the case of `mixed-parity' (but still regular
essentially self-dual) automorphic representations over totally real fields,
finding associated geometric projective representations. Finally, we optimize
some of the Galois lifting results of arxiv:1207.6724 and apply them to the
previous mixed-parity setting.


title:
Measurement of the g p -> K^0 Sigma^+ reaction with the Crystal
  Ball/TAPS detectors at the Mainz Microtron

abstract:
  The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45
GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers
together with the photon tagging facility at the Mainz Microtron MAMI. In the
present experiment, this reaction was searched for in the 3pi^0 p final state,
by assuming K^0_S -> pi^0 pi^0 and Sigma^+ -> pi^0 p. The experimental results
include total and differential cross sections as well as the polarization of
the recoil hyperon. The new data significantly improve empirical knowledge
about the g p -> K^0 Sigma^+ reaction in the measured energy range. The results
are compared to previous measurements and model predictions. It is demonstrated
that adding the present g p -> K^0 Sigma^+ results to existing data allowed a
better description of this reaction with various models.


title:
On the nature of the phase transitions in two-dimensional type II
  superconductors

abstract:
  We have simulated the thermodynamics of vortices in a thin film of a type-II
superconductor. We make the lowest Landau level approximation, and use
quasi-periodic boundary conditions. Our work is consistent with the results of
previous simulations where evidence was found for an apparent first order
transition between the vortex liquid state and the vortex crystal state. We
show, however, that these results are just an artifact of studying systems
which are too small. There are substantial difficulties in simulating larger
systems using traditional approaches. By means of the optimal energy diffusion
algorithm we have been able to study systems containing up to about one
thousand vortices, and for these larger systems the evidence for a first order
transition disappears. By studying both crystalline and hexatic order, we show
that the KTHNY scenario seems to apply, where melting from the crystal is first
to the hexatic liquid state and next to the normal vortex liquid, in both cases
via a continuous transition.


title: Quark masses, the Dashen phase, and gauge field topology

abstract:
  The CP violating Dashen phase in QCD is predicted by chiral perturbation
theory to occur when the up-down quark mass difference becomes sufficiently
large at fixed down-quark mass. Before reaching this phase, all physical
hadronic masses and scattering amplitudes are expected to behave smoothly with
the up-quark mass, even as this mass passes through zero. In Euclidean space,
the topological susceptibility of the gauge fields is positive at positive
quark masses but diverges to negative infinity as the Dashen phase is
approached. A zero in this susceptibility provides a tentative signal for the
point where the mass of the up quark vanishes. I discuss potential ambiguities
with this determination.


title:
Measurement of CP violation in the phase space of $B^{\pm} \to K^{\pm}
  \pi^{+} \pi^{-}$ and $B^{\pm} \to K^{\pm} K^{+} K^{-}$ decays

abstract:
  The charmless decays $B^{\pm}\to K^{\pm}\pi^+\pi^-$ and $B^{\pm}\to
K^{\pm}K^+K^-$ are reconstructed using data, corresponding to an integrated
luminosity of 1.0 fb$^{-1}$, collected by LHCb in 2011. The inclusive charge
asymmetries of these modes are measured as $A_{C\!P}(B^{\pm}\to
K^{\pm}\pi^+\pi^-) = 0.032 \pm 0.008 \stat \pm 0.004 \syst \pm 0.007 (J\psi
K^{\pm})$ and $A_{C\!P}(B^{\pm}\to K^{\pm}K^+K^-) = -0.043 \pm 0.009 \stat \pm
0.003 \syst \pm 0.007 (J\psi K^{\pm})$, where the third uncertainty is due to
the $C\!P$ asymmetry of the $B^{\pm}\to J\psi K^{\pm}$ reference mode. The
significance of $A_{C\!P}(B^{\pm}\to K^{\pm}K^+K^-)$ exceeds three standard
deviations and is the first evidence of an inclusive $C\!P$ asymmetry in
charmless three-body $B$ decays. In addition to the inclusive $C\!P$
asymmetries, larger asymmetries are observed in localised regions of phase
space.


title: Local supersymmetry without SUSY partners

abstract:
  A gauge theory for a superalgebra that includes an internal gauge (G) and
local Lorentz algebras, and that could describe the low energy particle
phenomenology is constructed. These two symmetries are connected by fermionic
supercharges. The system includes an internal gauge connection 1-form $A$, a
spin-1/2 Dirac spinor $\psi$, the Lorentz connection $\omega$, and the vielbein
$e$. The connection one-form is in the adjoint representation of G, while
$\psi$ is in the fundamental. In contrast to standard supergravity, the metric
is not a fundamental field and is in the center of the superalgebra: it is not
only invariant under the internal gauge group and under Lorentz
transformations, but is also invariant under supersymmetry. The features of
this theory that mark the difference with standard supersymmetry are: A) The
number of fermionic and bosonic states is not necessarily the same; B) There
are no superpartners with equal mass, "bosoninos", sleptons and squarks are
absent; C) Although this supersymmetry originates in a local gauge theory and
gravity is included, there is no gravitino; D) Fermions acquire mass from their
coupling to the background or from self-couplings, while bosons remain
massless. In odd dimensions, the Chern-Simons form provides an action that is
quasi-invariant under the entire superalgebra. In even dimensions, the
Yang-Mills form $ < F *F>$ is the only natural option, and the symmetry breaks
down to [G x SO(1,D-1)]. In 4D, the construction follows the Townsend - Mac
Dowell-Mansouri approach. Due to the absence of osp(4|2)-invariant traces in
four dimensions, the resulting Lagrangian is only invariant under [U(1) x
SO(3,1)], and includes a Nambu--Jona-Lasinio term. In this case, the Lagrangian
depends on a single dimensionful parameter that fixes Newton's constant, the
cosmological constant and the NJL coupling.


title: Electroweak hadron structure within a relativistic point-form approach

abstract:
  In this thesis a general relativistic framework for the calculation of the
electroweak structure of mesons of arbitrary constituent-quark masses is
presented. The physical processes in which the structure is measured, i.e.
electron-meson scattering and semileptonic weak decays, are treated in a
Poincar\'e invariant way by making use of the point-form of relativistic
quantum mechanics. The electromagnetic and weak meson currents are extracted
from the 1-photon or 1-W-exchange amplitudes that result from a
Bakamjian-Thomas type mass operator for the respective systems. The covariant
decomposition of these currents provides the electromagnetic and weak
(transition) form factors. The formalism is first applied to the study of
heavy-light systems. Problems with cluster separability, which are inherent in
the Bakamjian-Thomas construction, are discussed and it is shown how to keep
them under control. It is proved that the heavy-quark limit of the electroweak
form factors leads to one universal function, the Isgur-Wise function,
confirming that the requirements of heavy-quark symmetry are satisfied. These
results are discussed and compared with analogous calculations in the front
form of dynamics. The formalism is further applied to the study of bound states
whose binding is caused by dynamical particle exchange. The problem of how to
take into account retardation effects in the particle-exchange potential is
formulated and it is shown how they affect the binding energy and wave-function
solution for a dynamical model of the deuteron. At the end of this work an
example where the Clebsch-Gordan coefficients of the Poincar\'e group are
applied is presented. The angular momentum decomposition of chiral multiplets
is given in the instant and in the front forms.


title: Equilibrium states of soft magnetic hemispherical shell

abstract:
  The ground state of hemispherical permalloy magnetic shell is studied. There
exist two magnetic phases: the onion state and the vortex one. The phase
diagram is systematically analyzed in a wide range of geometrical parameters.
Possible transitions between different phases are analyzed using the
combination of analytical calculations and micromagnetic simulations.


title: Coherent ultrafast measurement of time-bin encoded photons

abstract:
  Time-bin encoding is a robust form of optical quantum information, especially
for transmission in optical fibers. To read out the information, the separation
of the time bins must be larger than the detector time resolution, typically on
the order of nanoseconds for photon counters. In the present work, we
demonstrate a technique using a nonlinear interaction between chirped entangled
time-bin photons and shaped laser pulses to perform projective measurements on
arbitrary time-bin states with picosecond-scale separations. We demonstrate a
tomographically-complete set of time-bin qubit projective measurements and show
the fidelity of operations is sufficiently high to violate the CHSH-Bell
inequality by more than 6 standard deviations.


title: Mixed-field orientation of a thermal ensemble of linear polar molecules

abstract:
  We present a theoretical study of the impact of an electrostatic field
combined with nonresonant linearly polarized laser pulses on the rotational
dynamics of a thermal ensemble of linear molecules. We solve the time-dependent
Schr\"odinger equation within the rigid rotor approximation for several
rotational states. Using the carbonyl sulfide (OCS) molecule as a prototype,
the mixed-field orientation of a thermal sample is analyzed in detail for
experimentally accessible static field strengths and laser pulses. We
demonstrate that for the characteristic field configuration used in current
mixed-field orientation experiments, a significant orientation is obtained for
rotational temperatures below 0.7K or using stronger dc fields.


title:
Gravitationally enhanced depolarization of ultracold neutrons in
  magnetic field gradients, and implications for neutron electric dipole moment
  measurements

abstract:
  Trapped ultracold neutrons (UCN) have for many years been the mainstay of
experiments to search for the electric dipole moment (EDM) of the neutron, a
critical parameter in constraining scenarios of new physics beyond the Standard
Model. Because their energies are so low, UCN preferentially populate the lower
region of their physical enclosure, and do not sample uniformly the ambient
magnetic field throughout the storage volume. This leads to a substantial
increase in the rate of depolarization, as well as to shifts in the measured
frequency of the stored neutrons. Consequences for EDM measurements are
discussed.


title:
Transverse magnetic field and chiral-nonchiral transition in vortex
  states for nearly B//ab in chiral p-wave superconductors

abstract:
  On the basis of Eilenberger theory, we study the vortex state when a magnetic
field is applied nearly parallel to the ab plane in a chiral p-wave
superconductor with a large anisotropy ratio of ab and c, as in Sr2RuO4. We
quantitatively estimate the field dependence of the pair potential,
magnetization, and flux line lattice form factor, and study the transition from
the chiral p_- state at low fields to the nonchiral p_y state at high fields.
Even for exactly parallel fields to the ab plane, transverse fields exist in
the chiral state. The chiral-nonchiral transition disappears when the magnetic
field orientation is tilted within 1 degree from the ab plane. This may be a
reason why the experimental detection of this transition is difficult.


title: A Single Universal n-bit Gate for Reversible Circuit Synthesis

abstract:
  Many universal reversible libraries that contain more than one gate type have
been proposed in the literature. Practical implementation of reversible
circuits is much easier if a single gate type is used in the circuit
construction. This paper proposes a reversible n-bit gate that is universal for
reversible circuits synthesis. The proposed gate is extendable according to the
size of the circuit. The paper shows that the size of the synthesized circuits
using the proposed gate is comparable with the size of the synthesized circuits
using the hybrid reversible libraries for 3-in/out reversible circuits.


title:
Semi-numeric simulations of helium reionization and the fluctuating
  radiation background

abstract:
  Recent He II Lyman-alpha forest observations from 2.0 < z < 3.2 show large
fluctuations in the optical depth at z > 2.7. These results point to a
fluctuating He-ionizing background, which may be due to the end of helium
reionization of this era. We present a fast, semi-numeric procedure to
approximate detailed cosmological simulations. We compute the distribution of
dark matter halos, ionization state of helium, and density field at z = 3 in
broad agreement with recent simulations. Given our speed and flexibility, we
investigate a range of ionizing source and active quasar prescriptions.
Spanning a large area of parameter space, we find order-of-magnitude
fluctuations in the He II ionization rate in the post-reionization regime.
During reionization, the fluctuations are even stronger and develop a bimodal
distribution, in contrast to semi-analytic models and the hydrogen equivalent.
These distributions indicate a low-level ionizing background even at
significant He II fractions.


title: Topology of open nonpositively curved manifolds

abstract:
  This is a survey of topological properties of open, complete nonpositively
curved manifolds which may have infinite volume. Topics include topology of
ends, restrictions on the fundamental group, as well as a review of known
examples.


The pasch configuration and Steiner triple systems


title: Quantization of Hall Conductance For Interacting Electrons on a Torus

abstract:
  We consider interacting, charged spins on a torus described by a gapped
Hamiltonian with a unique groundstate and conserved local charge. Using
quasi-adiabatic evolution of the groundstate around a flux-torus, we prove,
without any averaging assumption, that the Hall conductance of the groundstate
is quantized in integer multiples of e^2/h, up to exponentially small
corrections in the linear size of the system. In addition, we discuss
extensions to the fractional quantization case under an additional topological
order assumption on the degenerate groundstate subspace.


title: The computational complexity of density functional theory

abstract:
  Density functional theory is a successful branch of numerical simulations of
quantum systems. While the foundations are rigorously defined, the universal
functional must be approximated resulting in a `semi'-ab initio approach. The
search for improved functionals has resulted in hundreds of functionals and
remains an active research area. This chapter is concerned with understanding
fundamental limitations of any algorithmic approach to approximating the
universal functional. The results based on Hamiltonian complexity presented
here are largely based on \cite{Schuch09}. In this chapter, we explain the
computational complexity of DFT and any other approach to solving electronic
structure Hamiltonians. The proof relies on perturbative gadgets widely used in
Hamiltonian complexity and we provide an introduction to these techniques using
the Schrieffer-Wolff method. Since the difficulty of this problem has been well
appreciated before this formalization, practitioners have turned to a host
approximate Hamiltonians. By extending the results of \cite{Schuch09}, we show
in DFT, although the introduction of an approximate potential leads to a
non-interacting Hamiltonian, it remains, in the worst case, an NP-complete
problem.


title:
Electromagnetic cascade in high energy electron, positron, and photon
  interactions with intense laser pulses

abstract:
  The interaction of high energy electrons, positrons, and photons with intense
laser pulses is studied in head-on collision geometry. It is shown that
electrons and/or positrons undergo a cascade-type process involving multiple
emissions of photons. These photons can consequently convert into
electron-positron pairs. As a result charged particles quickly lose their
energy developing an exponentially decaying energy distribution, which
suppresses the emission of high energy photons, thus reducing the number of
electron-positron pairs being generated. Therefore, this type of interaction
suppresses the development of the electromagnetic avalanche-type discharge,
i.e., the exponential growth of the number of electrons, positrons, and photons
does not occur in the course of interaction. The suppression will occur when 3D
effects can be neglected in the transverse particle orbits, i.e., for
sufficiently broad laser pulses with intensities that are not too extreme. The
final distributions of electrons, positrons, and photons are calculated for the
case of a high energy e-beam interacting with a counter-streaming, short
intense laser pulse. The energy loss of the e-beam, which requires a
self-consistent quantum description, plays an important role in this process,
as well as provides a clear experimental observable for the transition from the
classical to quantum regime of interaction.


title:
Measurements of ultracold neutron upscattering and absorption in
  polyethylene and vanadium

abstract:
  The study of neutron cross sections for elements used as efficient
``absorbers'' of ultracold neutrons (UCN) is crucial for many precision
experiments in nuclear and particle physics, cosmology and gravity. In this
context, ``absorption'' includes both the capture and upscattering of neutrons
to the energies above the UCN energy region. The available data, especially for
hydrogen, do not agree between themselves or with the theory. In this report we
describe measurements performed at the Los Alamos National Laboratory UCN
facility of the UCN upscattering cross sections for vanadium and for hydrogen
in CH$_2$ using simultaneous measurements of the radiative capture cross
sections for these elements. We measured $\sigma_{up}=1972\pm130$ b for
hydrogen in CH$_2$, which is below theoretical expectations, and $\sigma_{up} <
25\pm9$ b for vanadium, in agreement with the expectation for the neutron
heating by thermal excitations in solids.


title: The parameter space of Cubic Galileon models for cosmic acceleration

abstract:
  We use recent measurements of the expansion history of the universe to place
constraints on the parameter space of cubic Galileon models, in particular we
concentrate on those models which contain the simplest Galileon term plus a
linear potential. This gives strong constraints on the Lagrangian of these
models. Most dynamical terms in the Galileon Lagrangian are constraint to be
small and the acceleration is effectively provided by a constant term in the
scalar potential, thus reducing, effectively, to a LCDM model for current
acceleration. The effective equation of state is indistinguishable from that of
a cosmological constant w = -1 and the data constraint it to have no temporal
variations of more than at the few % level. The energy density of the Galileon
can contribute only to about 10% of the acceleration energy density, being the
other 90% a cosmological constant term. This demonstrates how useful direct
measurements of the expansion history of the universe are at constraining the
dynamical nature of dark energy.


title:
Conductivity in the gravity dual to massive ABJM and the membrane
  paradigm

abstract:
  In this paper we analyze the effect of the massive deformation of the ABJM
model on the calculation of conductivity of the dual theory. We show that some
of the difficulties presented by the dual geometry, in particular the
construction of black holes therein, can be at least partially circumvented by
adopting a membrane paradigm-like computation of the conductivity, which
requires us to know just the effect of the deformation on the {\it horizon} of
a black hole in AdS${}_{4}$. The deformation at the horizon itself is found by
first deforming the flat space near the horizon, and then using the
corresponding solution near the horizon as initial conditions for the
Einstein's equations. We find the same result, showing an increase in
conductivity, using two types of membrane paradigm computations.


title: The Chills and Thrills of Whole Genome Sequencing

abstract:
  In recent years, Whole Genome Sequencing (WGS) evolved from a
futuristic-sounding research project to an increasingly affordable technology
for determining complete genome sequences of complex organisms, including
humans. This prompts a wide range of revolutionary applications, as WGS
promises to improve modern healthcare and provide a better understanding of the
human genome -- in particular, its relation to diseases and response to
treatments. However, this progress raises worrisome privacy and ethical issues,
since, besides uniquely identifying its owner, the genome contains a treasure
trove of highly personal and sensitive information. In this article, after
summarizing recent advances in genomics, we discuss some important privacy
issues associated with human genomic information and identify a number of
particularly relevant research challenges.


title: Sparse Covers for Sums of Indicators

abstract:
  For all $n, \epsilon >0$, we show that the set of Poisson Binomial
distributions on $n$ variables admits a proper $\epsilon$-cover in total
variation distance of size $n^2+n \cdot (1/\epsilon)^{O(\log^2 (1/\epsilon))}$,
which can also be computed in polynomial time. We discuss the implications of
our construction for approximation algorithms and the computation of
approximate Nash equilibria in anonymous games.


title: Mesoscopic dipolar quantum crystals

abstract:
  The ground state of a two-dimensional, harmonically confined mesoscopic
assembly of up to thirty polar molecules is studied by computer simulations. As
the strength of the confining trap is increased, clusters evolve from
superfluid, to supersolid, to insulating crystals. For strong confinement, the
crystalline structure can be predicted based on classical energetics. However,
clusters of specific numbers of particles (i.e., N=12 and N=19) display a {\it
non-classical crystalline structure}, stabilized by quantum effects, in an
intermediate range of confinement strength. In these cases, coexistence of
quantum and classical crystalline configurations is observed at finite
temperature.


title:
Loop Calculus and Bootstrap-Belief Propagation for Perfect Matchings on
  Arbitrary Graphs

abstract:
  This manuscript discusses computation of the Partition Function (PF) and the
Minimum Weight Perfect Matching (MWPM) on arbitrary, non-bipartite graphs. We
present two novel problem formulations - one for computing the PF of a Perfect
Matching (PM) and one for finding MWPMs - that build upon the inter-related
Bethe Free Energy, Belief Propagation (BP), Loop Calculus (LC), Integer Linear
Programming (ILP) and Linear Programming (LP) frameworks. First, we describe an
extension of the LC framework to the PM problem. The resulting formulas, coined
(fractional) Bootstrap-BP, express the PF of the original model via the BFE of
an alternative PM problem. We then study the zero-temperature version of this
Bootstrap-BP formula for approximately solving the MWPM problem. We do so by
leveraging the Bootstrap-BP formula to construct a sequence of MWPM problems,
where each new problem in the sequence is formed by contracting odd-sized
cycles (or blossoms) from the previous problem. This Bootstrap-and-Contract
procedure converges reliably and generates an empirically tight upper bound for
the MWPM. We conclude by discussing the relationship between our iterative
procedure and the famous Blossom Algorithm of Edmonds '65 and demonstrate the
performance of the Bootstrap-and-Contract approach on a variety of weighted PM
problems.


title: Strong Optomechanical Squeezing of Light

abstract:
  We create squeezed light by exploiting the quantum nature of the mechanical
interaction between laser light and a membrane mechanical resonator embedded in
an optical cavity. The radiation pressure shot noise (fluctuating optical force
from quantum laser amplitude noise) induces resonator motion well above that of
thermally driven motion. This motion imprints a phase shift on the laser light,
hence correlating the amplitude and phase noise, a consequence of which is
optical squeezing. We experimentally demonstrate strong and continuous
optomechanical squeezing of 1.7 +/- 0.2 dB below the shot noise level. The peak
level of squeezing measured near the mechanical resonance is well described by
a model whose parameters are independently calibrated and that includes thermal
motion of the membrane with no other classical noise sources.


title:
Single qubit manipulation in a microfabricated surface electrode ion
  trap

abstract:
  We trap individual $^{171}$Yb$^+$ ions in a surface trap microfabricated on a
silicon substrate, and demonstrate a complete set of high fidelity single qubit
operations for the hyperfine qubit. Trapping times exceeding 20 minutes without
laser cooling, and heating rates as low as 0.8(0.1) quanta/ms indicate stable
trapping conditions in these microtraps. A coherence time of more than one
second, high fidelity qubit state detection and single qubit rotations are
demonstrated.


title: Universal countable Borel quasi-orders

abstract:
  In recent years, much work in descriptive set theory has been focused on the
Borel complexity of naturally occurring classification problems, in particular,
the study of countable Borel equivalence relations and their structure under
the quasi-order of Borel reducibility. Following the approach of Louveau and
Rosendal for the study of analytic equivalence relations, we study countable
Borel quasi-orders.
  In this paper we are concerned with universal countable Borel quasi-orders,
i.e. countable Borel quasi-orders above all other countable Borel quasi-orders
with regard to Borel reducibility. We first establish that there is a universal
countable Borel quasi-order, and then establish that several countable Borel
quasi-orders are universal. An important example is an embeddability relation
on descriptive set theoretic trees.
  Our main result states that embeddability of finitely generated groups is a
universal countable Borel quasi-order, answering a question of Louveau and
Rosendal. This immediately implies that biembeddability of finitely generated
groups is a universal countable Borel equivalence relation. The same techniques
are also used to show that embeddability of countable groups is a universal
analytic quasi-order.
  Finally, we show that, up to Borel bireducibility, there are continuum-many
distinct countable Borel quasi-orders which symmetrize to a universal countable
Borel equivalence relation.