title: Group bases for some solvable groups and semidirect products

abstract:
  A set $B$ is a basis for a vector space $V$ if every element of $V$ can be
uniquely written as a linear combination of the elements of $B$. There is a
similar definition of a basis for a finite group. We show that certain
semidirect products of finite groups---including all semidirect products of
finite abelian groups---have bases; any group of order $m$ or $2m$ for odd,
cube-free $m$ has a basis; and the quaternions do not have a basis.


title:
Further Considerations Regarding the Aharonov-Bohm Effect and the
  Wavefunction of the Entire System

abstract:
  In an earlier paper it was demonstrated that the hypothesized electrostatic
version of the Aharonov-Bohm ("AB") effect does not exist. The conclusion
follows straightforwardly once one recognizes that interference takes place in
the configuration space of the entire system, including the experimental
apparatus, and the wavefunction of the apparatus cannot be ignored. Two
additional results are presented here. 1. Observations of interference that had
been attributed to an analogue of the electrostatic AB effect (or "scalar
effect") are actually due to a magnetic AB effect. 2. In the original magnetic
AB effect itself, there is no phase shift if it is possible effectively to
shield the solenoid from the influence of the passing electron. This result is
not in conflict with the landmark experiments of Tonomura and colleagues if
Wang's recent claim is correct, that superconductive shielding could not have
isolated the toroidal magnet from the magnetic pulse of the passing electron.


title:
Three-person impartial avoidance games for generating finite cyclic,
  dihedral, and nilpotent groups

abstract:
  We study a three-player variation of the impartial avoidance game introduced
by Anderson and Harary. Three players take turns selecting
previously-unselected elements of a finite group. The losing player is the one
who selects an element that causes the set of jointly-selected elements to be a
generating set for the group, with the previous player winning and the
remaining player coming in second place. We describe the winning strategy for
these games on cyclic, dihedral, and nilpotent groups.


title:
Nonexistence of small, odd breathers for a class of nonlinear wave
  equations

abstract:
  In this note, we show that for a large class of nonlinear wave equations with
odd nonlinearities, any globally defined odd solution which is small in the
energy space decays to $0$ in the local energy norm. In particular, this result
shows nonexistence of small, odd breathers for some classical nonlinear Klein
Gordon equations such as the sine Gordon equation and $\phi^4$ and $\phi^6$
models. It also partially answers a question of Soffer and Weinstein in
\cite[p. 19]{MR1681113} about nonexistence of breathers for the cubic NLKG in
dimension one.


title:
Quantum Information with Even/Odd States of Orbital Angular Momentum of
  Light

abstract:
  We address the possibility of using even/odd states of orbital angular
momentum (OAM) of photons for the quantum information tasks. Single photon
qubit states and two photon entangled states in even/odd basis of OAM are
considered. We present a method for the tomography and general projective
measurement in even/odd basis. With the general projective measurement, we show
the Bell violation and quantum cryptography with Bell's inequality. We also
describe hyper and hybrid entanglement of even/odd OAM states along with
polarization, which can be applied in the implementation of quantum protocols
like super dense coding.


title:
Slow running of the Gradient Flow coupling from 200 MeV to 4 GeV in
  $N_{\rm f}=3$ QCD

abstract:
  Using a finite volume Gradient Flow (GF) renormalization scheme with
Schr\"odinger Functional (SF) boundary conditions, we compute the
non-perturbative running coupling in the range $2.2 \lesssim {\bar
g}_\mathrm{GF}^2(L) \lesssim 13$. Careful continuum extrapolations turn out to
be crucial to reach our high accuracy. The running of the coupling is always
between one-loop and two-loop and very close to one-loop in the region of
$200\,{\rm MeV} \lesssim \mu=1/L \lesssim 4\,{\rm GeV}$. While there is no
convincing contact to two-loop running, we match non-perturbatively to the SF
coupling with background field. In this case we know the $\mu$ dependence up to
$\sim 100\,{\rm GeV}$ and can thus connect to the $\Lambda$-parameter.


title:
The random pseudo-metric on a graph defined via the zero-set of the
  Gaussian free field on its metric graph

abstract:
  We further investigate properties of the Gaussian free field (GFF) on the
metric graph associated to a discrete weighted graph (where the edges of the
latter are replaced by continuous line-segments of appropriate length) that has
been introduced by the first author. On such a metric graph, the GFF is a
random continuous function that generalises one-dimensional Brownian bridges so
that one-dimensional techniques can be used.
  In the present paper, we define and study the pseudo-metric defined on the
metric graph (and therefore also on the discrete graph itself), where the
length of a path on the metric graph is defined to be the local time at level
zero accumulated by the Gaussian free field along this path.
  We first derive a pathwise transformation that relates the GFF on the metric
graph with the reflected GFF on the metric graph via the pseudo-distance
defined by the latter. This is a generalisation of Paul L\'evy's result
relating the local time at zero of Brownian motion to the supremum of another
Brownian motion. We also compute explicitly the distribution of certain
functionals of this pseudo-metric and of the GFF. In particular, we point out
that when the boundary consists of just two points, the law of the
pseudo-distance between them depends solely on the resistance of the network
between them.
  We then discuss questions related to the scaling limit of this pseudo-metric
in the two-dimensional case, which should be the conformally invariant way to
measure distances between CLE(4) loops introduced and studied by the second
author with Wu, and by Sheffield, Watson and Wu. Our explicit laws on metric
graphs also lead to new conjectures for related functionals of the continuum
GFF on fairly general Riemann surfaces.


title:
Stability of a leap-frog discontinuous Galerkin method for time-domain
  Maxwell's equations in anisotropic materials

abstract:
  In this work we discuss the numerical discretization of the time-dependent
Maxwell's equations using a fully explicit leap-frog type discontinuous
Galerkin method. We present a sufficient condition for the stability, for cases
of typical boundary conditions, either perfect electric, perfect magnetic or
first order Silver-M\"uller. The bounds of the stability region point out the
influence of not only the mesh size but also the dependence on the choice of
the numerical flux and the degree of the polynomials used in the construction
of the finite element space, making possible to balance accuracy and
computational efficiency. In the model we consider heterogeneous anisotropic
permittivity tensors which arise naturally in many applications of interest.
Numerical results supporting the analysis are provided.


title:
A concrete realization of the slow-fast alternative for a semi linear
  heat equation with homogeneous Neumann boundary conditions

abstract:
  We investigate the asymptotic behavior of solutions to a semilinear heat
equation with homogeneous Neumann boundary conditions.
  It was recently shown that the nontrivial kernel of the linear part leads to
the coexistence of fast solutions decaying to 0 exponentially (as time goes to
infinity), and slow solutions decaying to 0 as negative powers of t.
  Here we provide a characterization of slow/fast solutions in terms of their
sign, and we show that the set of initial data giving rise to fast solutions is
a graph of codimension one in the phase space.


title:
Evaluating four-loop conformal Feynman integrals by D-dimensional
  differential equations

abstract:
  We evaluate a four-loop conformal integral, i.e. an integral over four
four-dimensional coordinates, by turning to its dimensionally regularized
version and applying differential equations for the set of the corresponding
213 master integrals. To solve these linear differential equations we follow
the strategy suggested by Henn and switch to a uniformly transcendental basis
of master integrals. We find a solution to these equations up to weight eight
in terms of multiple polylogarithms. Further, we present an analytical result
for the given four-loop conformal integral considered in four-dimensional
space-time in terms of single-valued harmonic polylogarithms. As a by-product,
we obtain analytical results for all the other 212 master integrals within
dimensional regularization, i.e. considered in D dimensions.


title: Analytic corrections to AdS by scalar matter and curvature squared term

abstract:
  We revisit the background solution for scalar matter coupled higher
derivative gravity originally reported in arXiv: 1409.8019[hep-th]. In this
letter, we choose a convenient ansatz for metric which determines the first
order perturbative corrections to scalar as well as geometry.


title: A Fine-grained Indoor Location-based Social Network

abstract:
  Existing Location-based social networks (LBSNs), e.g., Foursquare, depend
mainly on GPS or cellular-based localization to infer users' locations.
However, GPS is unavailable indoors and cellular-based localization provides
coarse-grained accuracy. This limits the accuracy of current LBSNs in indoor
environments, where people spend 89% of their time. This in turn affects the
user experience, in terms of the accuracy of the ranked list of venues,
especially for the small screens of mobile devices; misses business
opportunities; and leads to reduced venues coverage.
  In this paper, we present CheckInside: a system that can provide a
fine-grained indoor location-based social network. CheckInside leverages the
crowd-sensed data collected from users' mobile devices during the check-in
operation and knowledge extracted from current LBSNs to associate a place with
a logical name and a semantic fingerprint. This semantic fingerprint is used to
obtain a more accurate list of nearby places as well as to automatically detect
new places with similar signature. A novel algorithm for detecting fake
check-ins and inferring a semantically-enriched floorplan is proposed as well
as an algorithm for enhancing the system performance based on the user implicit
feedback. Furthermore, CheckInside encompasses a coverage extender module to
automatically predict names of new venues increasing the coverage of current
LBSNs.
  Experimental evaluation of CheckInside in four malls over the course of six
weeks with 20 participants shows that it can infer the actual user place within
the top five venues 99% of the time. This is compared to 17% only in the case
of current LBSNs. In addition, it increases the coverage of existing LBSNs by
more than 37%.


title: The topological Atiyah-Segal map

abstract:
  Associated to each finite dimensional linear representation of a group $G$,
there is a vector bundle over the classifying space $BG$. We introduce a
framework for studying this construction in the context of infinite discrete
groups, taking into account the topology of representation spaces.
  This involves studying the homotopy group completion of the topological
monoid formed by all unitary (or general linear) representations of $G$, under
the monoid operation given by block sum. In order to work effectively with this
object, we prove a general result showing that for certain homotopy commutative
topological monoids $M$, the homotopy groups of $\Omega BM$ can be described
explicitly in terms of unbased homotopy classes of maps from spheres into $M$.
  Several applications are developed. We relate our constructions to the
Novikov conjecture; we show that the space of flat unitary connections over the
3-dimensional Heisenberg manifold has extremely large homotopy groups; and for
groups that satisfy Kazhdan's property (T) and admit a finite classifying
space, we show that the reduced $K$-theory class associated to a spherical
family of finite dimensional unitary representations is always torsion.


title: Hybrid quantum systems for enhanced nonlinear optical susceptibilities

abstract:
  Significant effort has been expended in the search for materials with
ultra-fast nonlinear-optical susceptibilities, but most fall far below the
fundamental limits. This work applies a theoretical materials development
program that has identified a promising new hybrid made of a nanorod and a
molecule. This system uses the electrostatic dipole moment of the molecule to
break the symmetry of the metallic nanostructure that shifts the energy
spectrum to make it optimal for a nonlinear-optical response near the
fundamental limit. The structural parameters are varied to determine the ideal
configuration, providing guidelines for making the best structures.


title:
$A_1$ theory of weights for rough homogeneous singular integrals and
  commutators

abstract:
  Quantitative $A_1-A_\infty$ estimates for rough homogeneous singular
integrals $T_{\Omega}$ and commutators of $BMO$ symbols and $T_{\Omega}$ are
obtained. In particular the following estimates are proved: % \[ \|T_\Omega
\|_{L^p(w)}\le c_{n,p}\|\Omega\|_{L^\infty}
[w]_{A_1}^{\frac{1}{p}}\,[w]_{A_{\infty}}^{1+\frac{1}{p'}}\|f\|_{L^p(w)} \] %
and % \[ \| [b,T_{\Omega}]f\|_{L^{p}(w)}\leq
c_{n,p}\|b\|_{BMO}\|\Omega\|_{L^{\infty}}
[w]_{A_1}^{\frac{1}{p}}[w]_{A_{\infty}}^{2+\frac{1}{p'}}\|f\|_{L^{p}\left(w\right)},
\] % for $1<p<\infty$ and $1/p+1/p'=1$.


title: Uniformization of embedded surfaces

abstract:
  Let X be a closed surface of genus two embedded in the 3-sphere. Then X
inherits a metric and an orientation, which give an almost complex structure,
which automatically integrates to a genuine complex structure, making X a
Riemann surface. It follows that X is conformally isomorphic to a branched
cover of the Riemann sphere, or to the quotient of the unit disc by the action
of a Fuchsian group. The theorems behind these statements are important,
well-known, and a century old. Nonetheless, we believe that the literature
contains no examples where a significant fraction of the structure can be made
explicit. This monograph is a partially successful attempt to provide such an
example, starting with a particular surface X that has interesting geometry.
The required theory is surprisingly rich, and is supported by a large body of
Maple code, which is used for semi-formal verification of many proofs, as well
as for numerical calculation.


title: Gevrey Stability of Prandtl Expansions for 2D Navier-Stokes

abstract:
  We investigate the stability of boundary layer solutions of the
two-dimensional incompressible Navier-Stokes equations. We consider shear flow
solutions of Prandtl type : $$ u^\nu(t,x,y) \, = \, \big (U^E(t,y) +
U^{BL}(t,\frac{y}{\sqrt{\nu}})\,, \, 0 \big )\, , \quad 0<\nu \ll 1\,. $$ We
show that if $U^{BL}$ is monotonic and concave in $Y = y /\sqrt{\nu}$ then
$u^\nu$ is stable over some time interval $(0,T)$, $T$ independent of $\nu$,
under perturbations with Gevrey regularity in $x$ and Sobolev regularity in
$y$. We improve in this way the classical stability results of Sammartino and
Caflisch in analytic class (both in $x$ and $y$). Moreover, in the case where
$U^{BL}$ is steady and strictly concave, our Gevrey exponent for stability is
optimal. The proof relies on new and sharp resolvent estimates for the
linearized Orr-Sommerfeld operator.


title:
Magnetocapacitance oscillations and thermoelectric effect in
  two-dimensional electron gas irradiated by microwaves

abstract:
  To study the influence of microwave irradiation on two-dimensional electrons,
we apply a method based on capacitance measurements in GaAs quantum well
samples where the gate covers a central part of the layer. We find that the
capacitance oscillations at high magnetic fields, caused by the oscillations of
thermodynamic density of states, are not essentially modified by microwaves.
However, in the region of fields below 1 Tesla, we observe another set of
oscillation, with the period and the phase identical to those of microwave
induced resistance oscillations. The phenomenon of microwave induced
capacitance oscillations is explained in terms of violation of the Einstein
relation between conductivity and the diffusion coefficient in the presence of
microwaves, which leads to a dependence of the capacitor charging on the
anomalous conductivity. We also observe microwave-induced oscillations in the
capacitive response to periodic variations of external heating. These
oscillations appear due to the thermoelectric effect and are in antiphase with
microwave induced resistance oscillations because of the Corbino-like geometry
of our experimental setup.


title:
Gain and Polarization Properties of a Large Radio Telescope from
  Calculation and Measurement: The John A. Galt Telescope

abstract:
  Measurement of the brightness temperature of extended radio emission demands
knowledge of the gain (or aperture efficiency) of the telescope and measurement
of the polarized component of the emission requires correction for the
conversion of unpolarized emission from sky and ground to apparently polarized
signal. Radiation properties of the John A. Galt Telescope at the Dominion
Radio Astrophysical Observatory were studied through analysis and measurement
in order to provide absolute calibration of a survey of polarized emission from
the entire northern sky from 1280 to 1750 MHz, and to understand the
polarization performance of the telescope. Electromagnetic simulators CST and
GRASP-10 were used to compute radiation patterns of the telescope in all Stokes
parameters, and aperture efficiency. Aperture efficiency was also evaluated
using geometrical optics and was measured using Cyg A. Measured aperture
efficiency varied smoothly with frequency between values of 0.49 and 0.54;
GRASP-10 yielded values 6.5% higher but with closely similar variation with
frequency. Overall error across the frequency band is 3%, but values at any two
frequencies are relatively correct to ~1%. Dominant influences on aperture
efficiency are illumination taper of the feed radiation pattern and shadowing
by the feed-support struts. A model of ground emission was developed based on
measurements and on empirical data from remote sensing of the Earth from
satellite-borne telescopes. This model was convolved with the computed antenna
response to estimate conversion of ground emission into spurious polarized
signal. The computed spurious signal is comparable to measured values, but is
not accurate enough to be used to correct observations. A simpler model, in
which the ground is considered as an unpolarized emitter with a brightness
temperature of ~240 K, is shown to have useful accuracy when compared to
measurements.


title:
Fluid dynamics in the spirit of Cartan: A coordinate-free formulation of
  fluid dynamics for an inviscid fluid in inertial and non-inertial frames

abstract:
  Using Cartan's exterior calculus, we derive a coordinate-free formulation of
the Euler equations. These equations are invariant under Galileian
transformations, which constitute a global symmetry. With the introduction of
an appropriate generalized Coriolis force, these equations become symmetric
under general coordinate transformations.
  We show how exterior calculus simplifies dramatically the derivation of
conservation laws. We also discuss the advantage of an exterior calculus
formulation with respect to symmetry-preserving discretizations of the
equations.


title: Random Wave Function Collapse

abstract:
  Instability-induced random branching of deterministic dynamics is discussed
as a possible mechanism of random wave function collapse. In the case of two
level systems, the Born probability rule emerges as the simplest linear
solution to the equation for measurement probabilities.


title:
Mobility-Aware Modeling and Analysis of Dense Cellular Networks with
  C-plane/U-plane Split Architecture

abstract:
  The unrelenting increase in the population of mobile users and their traffic
demands drive cellular network operators to densify their network
infrastructure. Network densification shrinks the footprint of base stations
(BSs) and reduces the number of users associated with each BS, leading to an
improved spatial frequency reuse and spectral efficiency, and thus, higher
network capacity. However, the densification gain come at the expense of higher
handover rates and network control overhead. Hence, users mobility can diminish
or even nullifies the foreseen densification gain. In this context, splitting
the control plane (C-plane) and user plane (U-plane) is proposed as a potential
solution to harvest densification gain with reduced cost in terms of handover
rate and network control overhead. In this article, we use stochastic geometry
to develop a tractable mobility-aware model for a two-tier downlink cellular
network with ultra-dense small cells and C-plane/U-plane split architecture.
The developed model is then used to quantify the effect of mobility on the
foreseen densification gain with and without C-plane/U-plane split. To this
end, we shed light on the handover problem in dense cellular environments, show
scenarios where the network fails to support certain mobility profiles, and
obtain network design insights.


title:
On the challenge of estimating diphoton backgrounds at large invariant
  mass

abstract:
  Diphoton searches at high invariant mass are an integral part of the
experimental high energy frontier. Using the analyses of the 750\,GeV diphoton
resonance as a case study, we examine the methodology currently employed by the
experimental analyses in estimating the dominant standard model backgrounds. We
assess the dependence of the significance associated with the excess on the
background modeling. In particular, we show that close to the high energy tails
of the distributions, estimates of the jet faking backgrounds relying on
functional extrapolations or Monte Carlo estimates of the challenging
photon-jet contributions introduce a large uncertainty. Analyses with loose
photon cuts, low photon $p_T$ cuts and those susceptible to high photon
rapidity regions are especially affected. Given that diphoton-based searches
beyond 1\,TeV are highly motivated as discovery modes, these considerations are
relevant and applicable in the future.
  We first consider a physics-driven deformation of the shape of the diphoton
faking photon-jet spectrum by next-to-leading order effects combined with a
rapidity and transverse momentum dependent fake rate. We show that the
resulting local significance of the excess is reduced due to such a
deformation. Then using a simple, but more general, ansatz to modify the
contribution of the jet faking backgrounds at high invariant masses but keeping
the inclusive and differential sample purities within experimental uncertainty
estimates, we demonstrate that the originally reported local 750\,GeV excess
significances could have been overestimated by more than one standard
deviation. We furthermore cross-check our analysis by comparing fit results
based on the smaller 2015 and the larger 2016 LHC datasets. Finally we employ
our methodology on the complete 13\,TeV LHC dataset to asses the systematics
involved in the current diphoton searches beyond the TeV region.


title:
Possibility of an unconventional spin state of Ir$^{4+}$ in
  Ba$_{21}$Ir$_9$O$_{43}$ single crystal

abstract:
  We report the synthesis of single crystals of a novel layered iridate
Ba$_{21}$Ir$_9$O$_{43}$, and present the crystallographic, transport and
magnetic properties of this material. The compound has a hexagonal structure
with two iridium oxide layers stacked along the $c$ direction. One layer
consists of a triangular arrangement of Ir$_2$O$_9$ dimers while the other
layer comprises two regular octahedra and one triangular pyramid, forming
inter-penetrated triangular lattices. The resistivity as a function of
temperature exhibits an insulating behavior, with a peculiar $T^{-3}$ behavior.
Magnetic susceptibility shows antiferromagnetic Curie-Weiss behavior with
$\Theta_\mathrm{CW} \simeq -$90 K while a magnetic transition occurs at
substantially lower temperature of 9 K. We discuss possible valence states and
effective magnetic moments on Ir ions in different local environments, and
argue that the Ir ions in a unique triangular-pyramidal configuration likely
carry unusually large magnetic moments.


title: Metric Perturbation Resilience

abstract:
  We study the notion of perturbation resilience introduced by Bilu and Linial
(2010) and Awasthi, Blum, and Sheffet (2012). A clustering problem is
$\alpha$-perturbation resilient if the optimal clustering does not change when
we perturb all distances by a factor of at most $\alpha$. We consider a class
of clustering problems with center-based objectives, which includes such
problems as k-means, k-median, and k-center, and give an exact algorithm for
clustering 2-perturbation resilient instances. Our result improves upon the
result of Balcan and Liang (2016), who gave an algorithm for clustering
$1+\sqrt{2}\approx 2.41$ perturbation resilient instances. Our result is tight
in the sense that no polynomial-time algorithm can solve
$(2-\varepsilon)$-perturbation resilient instances unless NP = RP, as was shown
by Balcan, Haghtalab, and White (2016). We show that the algorithm works on
instances satisfying a slightly weaker and more natural condition than
perturbation resilience, which we call metric perturbation resilience.


title:
Distribution of star formation rates during the rapid assembly of NGC
  1399 as deduced from its globular cluster system

abstract:
  Ultra-compact dwarf galaxies (UCDs) share many properties with globular
clusters (GCs) and are found in similar environments. A large sample of UCDs
and GCs around NGC 1399, the central giant elliptical of the Fornax galaxy
cluster, is used to infer their formation history and also that of NGC 1399. We
assumed that all GCs and UCDs in our sample are star clusters (SCs) and used
them as tracers of past star formation activities. After correcting our GC/UCD
sample for mass loss, we interpreted their overall mass function to be a
superposition of SC populations that formed coevally during different times.
The SC masses of each population were distributed according to the embedded
cluster mass function (ECMF), a pure power law with the slope $-\beta$ and a
stellar upper mass limit, $M_{\mathrm{max}}$, which depended on the star
formation rate (SFR). We decomposed the observed GC/UCD mass function into
individual SC populations and converted $M_{\mathrm{max}}$ of each SC
population to an SFR. The overall distribution of SFRs reveals how the GC/UCD
sample formed. Considering the age of the GCs/UCDs and the present stellar mass
of NGC 1399, we found that the formation of the GCs/UCDs can be well explained
for $\beta<2.3$. This agrees very well with the observation in young SCs where
$\beta\approx2.0$ is usually found. Even if taking into account that some of
the most massive objects might not be genuine SCs and applying different
corrections for the mass loss, the outcome is not influenced much. We found
peak SFRs between approximately 300 and 3000 $M_{\odot}\mathrm{yr}^{-1}$, which
matches the SFRs observed in massive high-$z$ sub-mm galaxies and an SFR
estimate inferred from NGC 1399 based on "downsizing", i.e. more massive
galaxies must have formed over shorter times. Our results suggest that NGC 1399
and its GC/UCD system formed in an early, short, and intense starburst.


title: The Complexity of Drawing Graphs on Few Lines and Few Planes

abstract:
  It is well known that any graph admits a crossing-free straight-line drawing
in $\mathbb{R}^3$ and that any planar graph admits the same even in
$\mathbb{R}^2$. For a graph $G$ and $d \in \{2,3\}$, let $\rho^1_d(G)$ denote
the minimum number of lines in $\mathbb{R}^d$ that together can cover all edges
of a drawing of $G$. For $d=2$, $G$ must be planar. We investigate the
complexity of computing these parameters and obtain the following hardness and
algorithmic results.
  - For $d\in\{2,3\}$, we prove that deciding whether $\rho^1_d(G)\le k$ for a
given graph $G$ and integer $k$ is ${\exists\mathbb{R}}$-complete.
  - Since $\mathrm{NP}\subseteq{\exists\mathbb{R}}$, deciding $\rho^1_d(G)\le
k$ is NP-hard for $d\in\{2,3\}$. On the positive side, we show that the problem
is fixed-parameter tractable with respect to $k$.
  - Since ${\exists\mathbb{R}}\subseteq\mathrm{PSPACE}$, both $\rho^1_2(G)$ and
$\rho^1_3(G)$ are computable in polynomial space. On the negative side, we show
that drawings that are optimal with respect to $\rho^1_2$ or $\rho^1_3$
sometimes require irrational coordinates.
  - Let $\rho^2_3(G)$ be the minimum number of planes in $\mathbb{R}^3$ needed
to cover a straight-line drawing of a graph $G$. We prove that deciding whether
$\rho^2_3(G)\le k$ is NP-hard for any fixed $k \ge 2$. Hence, the problem is
not fixed-parameter tractable with respect to $k$ unless
$\mathrm{P}=\mathrm{NP}$.


title: Astrophysical Constraints on Singlet Scalars at LHC

abstract:
  We consider the viability of new heavy gauge singlet scalar particles at
colliders such as the LHC. Our original motivation for this study came from the
possibility of a new heavy particle of mass ~ TeV decaying significantly into
two photons at colliders, such as LHC, but our analysis applies more broadly.
We show that there are significant constraints from astrophysics and cosmology
on the simplest UV complete models that incorporate such new particles and its
associated collider signal. The simplest and most obvious UV complete model
that incorporates such signals is that it arises from a new singlet scalar (or
pseudo-scalar) coupled to a new electrically charged and colored heavy fermion.
Here we show that these new fermions (and anti-fermions) would be produced in
the early universe, then form new color singlet heavy mesons with light quarks,
obtain a non-negligible freeze-out abundance, and remain in kinetic equilibrium
until decoupling. These heavy mesons possess interesting phenomenology,
dependent on their charge, including forming new bound states with electrons
and protons. We show that a significant number of these heavy states would
survive for the age of the universe and an appreciable number would eventually
be contained within the earth and solar system. We show that this leads to
detectable consequences, including the production of highly energetic events
from annihilations on earth, new spectral lines, and, spectacularly, the
destabilization of stars. The lack of detection of these consequences rules out
such simple UV completions, putting pressure on the viability of such new
particles at LHC. To incorporate such a scalar would require either much more
complicated UV completions or even further new physics that provides a decay
channel for the associated fermion.


title:
Observation of $\eta_{c}(2S) \to p \bar p$ and search for $X(3872) \to p
  \bar p$ decays

abstract:
  The first observation of the decay $\eta_{c}(2S) \to p \bar p$ is reported
using proton-proton collision data corresponding to an integrated luminosity of
$3.0\rm \, fb^{-1}$ recorded by the LHCb experiment at centre-of-mass energies
of 7 and 8 TeV. The $\eta_{c}(2S)$ resonance is produced in the decay $B^{+}
\to [c\bar c] K^{+}$. The product of branching fractions normalised to that for
the $J/\psi$ intermediate state, ${\cal R}_{\eta_{c}(2S)}$, is measured to be
\begin{align*} {\cal R}_{\eta_{c}(2S)}\equiv\frac{{\mathcal B}(B^{+} \to
\eta_{c}(2S) K^{+}) \times {\mathcal B}(\eta_{c}(2S) \to p \bar p)}{{\mathcal
B}(B^{+} \to J/\psi K^{+}) \times {\mathcal B}(J/\psi\to p \bar p)} =~& (1.58
\pm 0.33 \pm 0.09)\times 10^{-2}, \end{align*} where the first uncertainty is
statistical and the second systematic. No signals for the decays $B^{+} \to
X(3872) (\to p \bar p) K^{+}$ and $B^{+} \to \psi(3770) (\to p \bar p) K^{+}$
are seen, and the 95\% confidence level upper limits on their relative
branching ratios are % found to be ${\cal R}_{X(3872)}<0.25\times10^{-2}$ and
${\cal R}_{\psi(3770))}<0.10$. In addition, the mass differences between the
$\eta_{c}(1S)$ and the $J/\psi$ states, between the $\eta_{c}(2S)$ and the
$\psi(2S)$ states, and the natural width of the $\eta_{c}(1S)$ are measured as
\begin{align*} M_{J/\psi} - M_{\eta_{c}(1S)} =~& 110.2 \pm 0.5 \pm 0.9 \rm \,
MeV, M_{\psi(2S)} -M_{\eta_{c}(2S)} =~ & 52.5 \pm 1.7 \pm 0.6 \rm \, MeV,
\Gamma_{\eta_{c}(1S)} =~& 34.0 \pm 1.9 \pm 1.3 \rm \, MeV. \end{align*}


title:
Handling Missing Data in Within-Trial Cost-Effectiveness Analysis: a
  Review with Future Guidelines

abstract:
  Cost-Effectiveness Analyses (CEAs) alongside randomised controlled trials
(RCTs) are increasingly often designed to collect resource use and
preference-based health status data for the purpose of healthcare technology
assessment. However, because of the way these measures are collected, they are
prone to missing data, which can ultimately affect the decision of whether an
intervention is good value for money. We examine how missing cost and effect
outcome data are handled in RCT-based CEAs, complementing a previous review
(covering 2003-2009, 88 articles) with a new systematic review (2009-2015, 81
articles) focussing on two different perspectives. First, we review the
description of the missing data, the statistical methods used to deal with
them, and the quality of the judgement underpinning the choice of these
methods. Second, we provide guidelines on how the information about missingness
and related methods should be presented to improve the reporting and handling
of missing data. Our review shows that missing data in within-RCT CEAs are
still often inadequately handled and the overall level of information provided
to support the chosen methods is rarely satisfactory.


title: Renormalization group coefficients and the S-matrix

abstract:
  We show how to use on-shell unitarity methods to calculate renormalization
group coefficients such as beta functions and anomalous dimensions. The central
objects are the form factors of composite operators. Their discontinuities can
be calculated via phase-space integrals and are related to corresponding
anomalous dimensions. In particular, we find that the dilatation operator,
which measures the anomalous dimensions, is given by minus the phase of the
S-matrix divided by pi. We illustrate our method using several examples from
Yang-Mills theory, perturbative QCD and Yukawa theory at one-loop level and
beyond.


title:
First-principles approach to excitons in time-resolved and
  angle-resolved photoemission spectra

abstract:
  We show that any {\em quasi-particle} or GW approximation to the self-energy
does not capture excitonic features in time-resolved (TR) photoemission
spectroscopy. In this work we put forward a first-principles approach and
propose a feasible diagrammatic approximation to solve this problem. We also
derive an alternative formula for the TR photocurrent which involves a single
time-integral of the lesser Green's function. The diagrammatic approximation
applies to the {\em relaxed} regime characterized by the presence of
quasi-stationary excitons and vanishing polarization. The main distinctive
feature of the theory is that the diagrams must be evaluated using {\em
excited} Green's functions. As this is not standard the analytic derivation is
presented in detail. The final result is an expression for the lesser Green's
function in terms of quantities that can all be calculated {\em ab initio}. The
validity of the proposed theory is illustrated in a one-dimensional model
system with a direct gap. We discuss possible scenarios and highlight some
universal features of the exciton peaks. Our results indicate that the exciton
dispersion can be observed in TR {\em and} angle-resolved photoemission.


title: Layer Normalization

abstract:
  Training state-of-the-art, deep neural networks is computationally expensive.
One way to reduce the training time is to normalize the activities of the
neurons. A recently introduced technique called batch normalization uses the
distribution of the summed input to a neuron over a mini-batch of training
cases to compute a mean and variance which are then used to normalize the
summed input to that neuron on each training case. This significantly reduces
the training time in feed-forward neural networks. However, the effect of batch
normalization is dependent on the mini-batch size and it is not obvious how to
apply it to recurrent neural networks. In this paper, we transpose batch
normalization into layer normalization by computing the mean and variance used
for normalization from all of the summed inputs to the neurons in a layer on a
single training case. Like batch normalization, we also give each neuron its
own adaptive bias and gain which are applied after the normalization but before
the non-linearity. Unlike batch normalization, layer normalization performs
exactly the same computation at training and test times. It is also
straightforward to apply to recurrent neural networks by computing the
normalization statistics separately at each time step. Layer normalization is
very effective at stabilizing the hidden state dynamics in recurrent networks.
Empirically, we show that layer normalization can substantially reduce the
training time compared with previously published techniques.


title:
Space-time vortex driven crossover and vortex turbulence phase
  transition in one-dimensional driven open condensates

abstract:
  We find a first order transition driven by the strength of non-equilibrium
conditions of one-dimensional driven open condensates. Associated with this
transition is a new stable non-equilibrium phase, space-time vortex turbulence,
whose vortex density and quasiparticle distribution show strongly non-thermal
behavior. Below the transition, we identify a new time scale associated with
noise activated unbound space-time vortices, beyond which the temporal
coherence function changes from a Kardar-Parisi-Zhang type subexponential to a
disordered exponential decay. Experimental realization of the non-equilibrium
vortex turbulent phase is facilitated in driven open condensates with a large
diffusion rate.


title:
A Census of Large-Scale ($\ge$ 10 pc), Velocity-Coherent, Dense
  Filaments in the Northern Galactic Plane: Automated Identification Using
  Minimum Spanning Tree

abstract:
  Large-scale gaseous filaments with length up to the order of 100 pc are on
the upper end of the filamentary hierarchy of the Galactic interstellar medium.
Their association with respect to the Galactic structure and their role in
Galactic star formation are of great interest from both observational and
theoretical point of view. Previous "by-eye" searches, combined together, have
started to uncover the Galactic distribution of large filaments, yet inherent
bias and small sample size limit conclusive statistical results to be drawn.
Here, we present (1) a new, automated method to identify large-scale
velocity-coherent dense filaments, and (2) the first statistics and the
Galactic distribution of these filaments. We use a customized minimum spanning
tree algorithm to identify filaments by connecting voxels in the
position-position-velocity space, using the Bolocam Galactic Plane Survey
spectroscopic catalog. In the range of $7.^{\circ}5 \le l \le 194^{\circ}$, we
have identified 54 large-scale filaments and derived mass ($\sim 10^3 - 10^5 \,
M_\odot$), length (10-276 pc), linear mass density (54-8625 $M_\odot \,
\rm{pc}^{-1}$), aspect ratio, linearity, velocity gradient, temperature,
fragmentation, Galactic location and orientation angle. The filaments
concentrate along major spiral arms. They are widely distributed across the
Galactic disk, with 50% located within $\pm$20 pc from the Galactic mid-plane
and 27% run in the center of spiral arms (aka "bones"). An order of 1% of the
molecular ISM is confined in large filaments. Massive star formation is more
favorable in large filaments compared to elsewhere. This is the first
comprehensive catalog of large filaments useful for a quantitative comparison
with spiral structures and numerical simulations.


title:
Numerical Simulation of Vertical Oscillations in an Axisymmetric Thick
  Accretion Flow around a Black Hole

abstract:
  We study time evolution of rotating, axisymmetric, two dimensional inviscid
accretion flows around black holes using a grid based finite difference method.
We do not use reflection symmetry on the equatorial plane in order to inspect
if the disk along with the centrifugal barrier oscillated vertically. In the
inviscid limit, we find that the CENtrifugal pressure supported BOundary Layer
(CENBOL) is oscillating vertically, more so, when the specific angular momentum
is higher. As a result, the rate of outflow produced from the CENBOL, also
oscillates. Indeed, the outflow rates in the upper half and the lower half are
found to be anti-correlated. We repeat the exercise for a series of specific
angular momentum {\lambda} of the flow in order to demonstrate effects of the
centrifugal force on this interesting behaviour. We find that, as predicted in
theoretical models of disks in vertical equilibrium, the CENBOL is produced
only when the centrifugal force is significant and more specifically, when
{\lambda} > 1.5. Outflow rate itself is found to increase with {\lambda} as
well and so is the oscillation amplitude. The cause of oscillation appears to
be due to the interaction among the back flow from the centrifugal barrier, the
outflowing winds and the inflow. For low angular momentum, the back flow as
well as the oscillation are missing. To our knowledge, this is the first time
that such an oscillating solution is found with an well-tested grid based
finite difference code and such a solution could be yet another reason of why
Quasi-Periodic Oscillations should be observed in black hole candidates which
are accreting low angular momentum transonic flows.


title: Sofic entropy, after Lewis Bowen, David Kerr and Hanfeng Li

abstract:
  The entropy in dynamical systems was introduced by A. Kolmogorov. Initially
dedicated to iterations of one finite measure preserving transformation, the
notion was gradually generalized so as to encompass amenable group actions and
topological actions. L. Bowen (2008) succeeded in breaking the non-amenable
frontier by introducing the sofic entropy. This invariant provides the same
services as the classical entropy for the measured actions of the sofic groups
(a class which contains the residually finite groups). In 2010, D. Kerr et H.
Li established a topological version together with a variational principle.


title:
A Global Prospective of the Indian Optical and Near-Infrared
  Observational Facilities in the Field of Astronomy and Astrophysics: a review

abstract:
  A review of modernization and growth of ground based optical and
near-infrared astrophysical observational facilities in the globe attributed to
the recent technological developments in optomechanical, electronics and
computer science areas is presented. Hubble Space Telescope (HST) and speckle
and adaptive ground based imaging have obtained images better than 0.1 arc sec
angular resolution bringing the celestial objects closer to us at least by a
factor of 10 during the last two decades. From the light gathering point of
view, building of large size (more than 5 meter aperture) ground based optical
and nearinfrared telescopes based on latest technology have become economical
in recent years. Consequently, in the world, a few 8-10 meter size ground-based
optical and near-infrared telescopes are being used for observations of the
celestial objects, three 25-40 meter size are under design stage and making of
a ~ 100 meter size telescope is under planning stage. In India, the largest
sized optical and near-infrared telescope is the modern 3.6-meter located at
Devasthal, Nainital. However, the existing Indian moderate size telescopes
equipped with modern backend instruments have global importance due to their
geographical location. Recently, participation of India in the Thirty Meter
Telescope (TMT) project has been approved by the Government of India.


title:
Bounds on the number of conjugacy classes of the symmetric and
  alternating groups

abstract:
  Let $G$ be a finite group with Sylow subgroups $P_1,\ldots,P_n$, and let
$k(G)$ denote the number of conjugacy classes of $G$. Pyber asked if $k(G) \leq
\prod_{i=1}^n k(P_i)$ for all finite groups $G$. With the help of GAP, we prove
that Pyber's inequality holds for all symmetric and alternating groups.


title:
No-Go Theorem for Boson Condensation in Topologically Ordered Quantum
  Liquids

abstract:
  Certain phase transitions between topological quantum field theories (TQFT)
are driven by the condensation of bosonic anyons. However, as bosons in a TQFT
are themselves nontrivial collective excitations, there can be topological
obstructions that prevent them from condensing. Here we formulate such an
obstruction in the form of a no-go theorem. We use it to show that no
condensation is possible in SO(3)$_k$ TQFTs with odd $k$. We further show that
a layered theory obtained by tensoring SO(3)$_k$ TQFT with itself any integer
number of times does not admit condensation transitions either. This includes
(as the case $k=3$) the noncondensability of any number of layers of the
Fibonacci TQFT.


title: Constraining the Dark Energy Equation of State with HII Galaxies

abstract:
  We use the HII galaxies $L - \sigma$ relation and the resulting Hubble
expansion cosmological probe of a sample of just 25 high-$z$ (up to $z \sim
2.33$) HII galaxies, in a joint likelihood analysis with other well tested
cosmological probes (CMB, BAOs) in an attempt to constrain the dark energy
equation of state (EoS). The constraints, although still weak, are in excellent
agreement with those of a similar joint analysis using the well established
SNIa Hubble expansion probe. Interestingly, even with the current small number
of available high redshift HII galaxies, the HII/BAO/CMB joint analysis gives a
13% improvement of the quintessence dark energy cosmological constraints
compared to the BAO/CMB joint analysis. We have further performed extensive
Monte Carlo simulations, with a realistic redshift sampling, to explore the
extent to which the use of the $L - \sigma$ relation, observed in HII galaxies,
can constrain effectively the parameter space of the dark energy EoS. The
simulations predict substantial improvement in the constraints when increasing
the sample of high-$z$ HII galaxies to 500, a goal that can be achieved in
reasonable observing times with existing large telescopes and state-of-the-art
instrumentation.


title:
Extreme star formation events in quasar hosts over
  ${\bf0.5<\textit{z}<4}$

abstract:
  We explore the relationship between active galactic nuclei and star formation
in a sample of 513 optically luminous type 1 quasars up to redshifts of $\sim$4
hosting extremely high star formation rates (SFRs). The quasars are selected to
be individually detected by the \textit{Herschel} SPIRE instrument at $>
$3$\sigma$ at 250 $\mu$m, leading to typical SFRs of order of 1000
M$_{\odot}$yr$^{-1}$. We find the average SFRs to increase by almost a factor
10 from $z\sim0.5$ to $z\sim3$, mirroring the rise in the comoving SFR density
over the same epoch. However, we find that the SFRs remain approximately
constant with increasing accretion luminosity for accretion luminosities above
10$^{12}$ L$_{\odot}$. We also find that the SFRs do not correlate with black
hole mass. Both of these results are most plausibly explained by the existence
of a self-regulation process by the starburst at high SFRs, which controls SFRs
on time-scales comparable to or shorter than the AGN or starburst duty cycles.
We additionally find that SFRs do not depend on Eddington ratio at any
redshift, consistent with no relation between SFR and black hole growth rate
per unit black hole mass. Finally, we find that high-ionisation broad
absorption line (HiBAL) quasars have indistinguishable far-infrared properties
to those of classical quasars, consistent with HiBAL quasars being normal
quasars observed along a particular line of sight, with the outflows in HiBAL
quasars not having any measurable effect on the star formation in their hosts.


title: Tensor-Network Simulations of the Surface Code under Realistic Noise

abstract:
  The surface code is a many-body quantum system, and simulating it in generic
conditions is computationally hard. While the surface code is believed to have
a high threshold, the numerical simulations used to establish this threshold
are based on simplified noise models. We present a tensor-network algorithm for
simulating error correction with the surface code under arbitrary local noise.
We use this algorithm to study the threshold and the subthreshold behavior of
the amplitude-damping and systematic rotation channels. We also compare these
results to those obtained by making standard approximations to the noise
models.


title:
Direct measurement of discrete valley and orbital quantum numbers in a
  multicomponent quantum Hall system

abstract:
  Strongly interacting two dimensional electron systems (2DESs) host a complex
landscape of broken symmetry states. The possible ground states are further
expanded by internal degrees of freedom such as spin or valley-isospin. While
direct probes of spin in 2DESs were demonstrated two decades ago, the valley
quantum number has only been probed indirectly in semiconductor quantum wells,
graphene mono- and bilayers, and transition-metal dichalcogenides. Here, we
present the first direct experimental measurement of valley polarization in a
two dimensional electron system, effected via the direct mapping of the valley
quantum number onto the layer polarization in bilayer graphene at high magnetic
fields. We find that the layer polarization evolves in discrete steps across 32
electric field-tuned phase transitions between states of different valley,
spin, and orbital polarization. Our data can be fit by a model that captures
both single particle and interaction induced orbital, valley, and spin
anisotropies, providing the most complete model of this complex system to date.
Among the newly discovered phases are theoretically unanticipated orbitally
polarized states stabilized by skew interlayer hopping. The resulting roadmap
to symmetry breaking in bilayer graphene paves the way for deterministic
engineering of fractional quantum Hall states, while our layer-resolved
technique is readily extendable to other two dimensional materials where layer
polarization maps to the valley or spin quantum numbers, providing an essential
direct probe that is a prerequisite for manipulating these new quantum degrees
of freedom.


title:
MOA-II Galactic Microlensing Constraints: The Inner Milky Way has a Low
  Dark Matter Fraction and a Near Maximal Disk

abstract:
  Microlensing provides a unique tool to break the stellar to dark matter
degeneracy in the inner Milky Way. We combine N-body dynamical models fitted to
the Milky Way's Boxy/Peanut bulge with exponential disk models outside this,
and compute the microlensing properties. Considering the range of models
consistent with the revised MOA-II data, we find low dark matter fractions in
the inner Galaxy: at the peak of their stellar rotation curve a fraction
$f_v=(0.88\pm0.07)$ of the circular velocity is baryonic (at $1\sigma$, $f_v >
0.72$ at $2\sigma$). These results are in agreement with constraints from the
EROS-II microlensing survey of brighter resolved stars, where we find
$f_v=(0.9\pm0.1)$ at $1\sigma$. Our fiducial model of a disk with scale length
2.6kpc, and a bulge with a low dark matter fraction of 12%, agrees with both
the revised MOA-II and EROS-II microlensing data. The required baryonic
fractions, and the resultant low contribution from dark matter, are consistent
with the NFW profiles produced by dissipationless cosmological simulations in
Milky Way mass galaxies. They are also consistent with recent prescriptions for
the mild adiabatic contraction of Milky Way mass haloes without the need for
strong feedback, but there is some tension with recent measurements of the
local dark matter density. Microlensing optical depths from the larger OGLE-III
sample could improve these constraints further when available.


title: Einsteinian cubic gravity

abstract:
  We drastically simplify the problem of linearizing a general higher-order
theory of gravity. We reduce it to the evaluation of its Lagrangian on a
particular Riemann tensor depending on two parameters, and the computation of
two derivatives with respect to one of those parameters. We use our method to
construct a D-dimensional cubic theory of gravity which satisfies the following
properties: 1) it shares the spectrum of Einstein gravity, i.e., it only
propagates a transverse and massless graviton on a maximally symmetric
background; 2) the relative coefficients of the different curvature invariants
involved are the same in all dimensions; 3) it is neither trivial nor
topological in four dimensions. Up to cubic order in curvature, the only
previously known theories satisfying the first two requirements are the
Lovelock ones: Einstein gravity, Gauss-Bonnet and cubic-Lovelock. Of course,
the last two theories fail to satisfy requirement 3 as they are, respectively,
topological and trivial in four dimensions. We show that, up to cubic order,
there exists only one additional theory satisfying requirements 1 and 2.
Interestingly, this theory is, along with Einstein gravity, the only theory
which also satisfies 3.


title:
ALMACAL II: Extreme star-formation-rate densities in a pair of dusty
  starbursts at $z = 3.442$ revealed by ALMA 20-milliarcsec resolution imaging

abstract:
  We present ALMA ultra-high-spatial resolution ($\sim 20 \, {\rm mas}$)
observations of dust continuum at $920 \, {\rm \mu m}$ and $1.2 \, {\rm mm}$ in
a pair of submm galaxies (SMGs) at $z = 3.442$, ALMACAL-1 (A-1: $S_{\rm 870 \mu
m} = 6.5 \pm 0.2 \, {\rm mJy}$) and ALMACAL-2 (A-2: $S_{\rm 870 \mu m} = 4.4
\pm 0.2 \, {\rm mJy}$). The spectroscopic redshifts of A-1 and A-2 have been
confirmed via serendipitous detection of up to nine emission lines. Our
ultra-high-spatial resolution data reveal that about half of the star formation
in each of these starbursts is dominated by a single compact clump (FWHM size
of $\sim 350 \, {\rm pc}$). This structure is confirmed by independent datasets
at $920 \, {\rm \mu m}$ and $1.2 \, {\rm mm}$. The star-formation rate (SFR)
surface densities of all these clumps are extremely high, $\Sigma_{\rm SFR}
\sim 1200$ to $\sim 3000 \, {M_\odot \, {\rm yr}^{-1} \, {\rm kpc}^{-2}}$, the
highest found in high-redshift galaxies. There is a small probability that A-1
and A-2 are the lensed components of a background source gravitationally
amplified by the blazar host. If this was the case, the effective radius of the
source would be $R_{\rm eff} \sim 40 \, {\rm pc}$, and the de-magnified SFR
surface density would be $\Sigma_{\rm SFR} \sim 10000 \, {M_\odot \, {\rm
yr}^{-1} \, {\rm kpc}^{-2}}$, comparable with the eastern nucleus of Arp 220.
Despite being unable to rule out an AGN contribution, our results suggest that
a significant percentage of the enormous far-IR luminosity in some dusty
starbursts is concentrated in very small star-forming regions. The high
$\Sigma_{\rm SFR}$ in our pair of SMGs could only be measured thanks to the
ultra-high-resolution ALMA observations used in this work, demonstrating that
long-baseline observations are essential to study and interpret the properties
of dusty starbursts in the early Universe.


title:
The First Distance Constraint on the Renegade High Velocity Cloud
  Complex WD

abstract:
  We present medium-resolution, near-ultraviolet VLT/FLAMES observations of the
star USNO-A0600-15865535. We adapt a standard method of stellar typing to our
measurement of the shape of the Balmer epsilon absorption line to demonstrates
that USNO-A0600-15865535 is a blue horizontal branch star, residing in the
lower stellar halo at a distance of 4.4 kpc from the Sun. We measure the H & K
lines of singly-ionized calcium and find two isolated velocity components, one
originating in the disk, and one associated with high-velocity cloud complex
WD. This detection demonstrated that complex WD is closer than ~4.4 kpc and is
the first distance constraint on the +100 km/s Galactic complex of clouds. We
find that Complex WD is not in corotation with the Galactic disk as has been
assumed for decades. We examine a number of scenarios, and find that the most
likely is that Complex WD was ejected from the solar neighborhood and is only a
few kpc from the Sun.


title:
The supermassive black hole and double nucleus of the core elliptical
  NGC5419

abstract:
  We obtained adaptive-optics assisted SINFONI observations of the central
regions of the giant elliptical galaxy NGC5419 with a spatial resolution of 0.2
arcsec ($\approx 55$ pc). NGC5419 has a large depleted stellar core with a
radius of 1.58 arcsec (430 pc). HST and SINFONI images show a point source
located at the galaxy's photocentre, which is likely associated with the
low-luminosity AGN previously detected in NGC5419. Both the HST and SINFONI
images also show a second nucleus, off-centred by 0.25 arcsec ($\approx 70$
pc). Outside of the central double nucleus, we measure an almost constant
velocity dispersion of $\sigma \sim 350$ km/s. In the region where the double
nucleus is located, the dispersion rises steeply to a peak value of $\sim 420$
km/s. In addition to the SINFONI data, we also obtained stellar kinematics at
larger radii from the South African Large Telescope. While NGC5419 shows low
rotation ($v < 50$ km/s), the central regions (inside $\sim 4 \, r_b$) clearly
rotate in the opposite direction to the galaxy's outer parts. We use
orbit-based dynamical models to measure the black hole mass of NGC5419 from the
kinematical data outside of the double nuclear structure. The models imply
M$_{\rm BH}=7.2^{+2.7}_{-1.9} \times 10^9$ M$_{\odot}$. The enhanced velocity
dispersion in the region of the double nucleus suggests that NGC5419 possibly
hosts two supermassive black holes at its centre, separated by only $\approx
70$ pc. Yet our measured M$_{\rm BH}$ is consistent with the black hole mass
expected from the size of the galaxy's depleted stellar core. This suggests,
that systematic uncertainties in M$_{\rm BH}$ related to the secondary nucleus
are small.


title:
On the Contribution of Active Galactic Nuclei to the High-Redshift
  Metagalactic Ionizing Background

abstract:
  Motivated by the claimed detection of a large population of faint active
galactic nuclei (AGN) at high redshift, recent studies have proposed models in
which AGN contribute significantly to the z > 4 H I ionizing background. In
some models, AGN are even the chief sources of reionization. If correct, these
models would make necessary a complete revision to the standard view that
galaxies dominated the high-redshift ionizing background. It has been suggested
that AGN-dominated models can better account for two recent observations that
appear to be in conflict with the standard view: (1) large opacity variations
in the z ~ 5.5 H I Lyman-alpha forest, and (2) slow evolution in the mean
opacity of the He II Lyman-alpha forest. Large spatial fluctuations in the
ionizing background from the brightness and rarity of AGN may account for the
former, while the earlier onset of He II reionization in these models may
account for the latter. Here we show that models in which AGN emissions source
>~ 50 % of the ionizing background generally provide a better fit to the
observed H I Lyman-alpha forest opacity variations compared to standard
galaxy-dominated models. However, we argue that these AGN-dominated models are
in tension with constraints on the thermal history of the intergalactic medium
(IGM). Under standard assumptions about the spectra of AGN, we show that the
earlier onset of He II reionization heats up the IGM well above recent
temperature measurements. We further argue that the slower evolution of the
mean opacity of the He II Lyman-alpha forest relative to simulations may
reflect deficiencies in current simulations rather than favor AGN-dominated
models as has been suggested.


title:
NLO+NLL Collider Bounds, Dirac Fermion and Scalar Dark Matter in the B-L
  Model

abstract:
  Baryon and lepton numbers being accidental global symmetries of the Standard
Model (SM), it is natural to promote them to local symmetries. However, to
preserve anomaly freedom, only combinations of B-L are viable. In this spirit,
we investigate possible dark matter realizations in the context of the
$U(1)_{B-L}$ model: (i) Dirac fermion with unbroken B-L; (ii) Dirac fermion
with broken B-L; (iii) scalar dark matter; (iv) two component dark matter. We
compute the relic abundance, direct and indirect detection observables and
confront them with recent results from Planck, LUX-2016, and Fermi-LAT and
prospects from XENON1T. In addition to the well known LEP bound
$M_{Z^{\prime}}/g_{BL} \gtrsim 7$ TeV, we include often ignored LHC bounds
using 13 TeV dilepton (dimuon+dielectron) data at next-to-leading order plus
next-to-leading logarithmic accuracy. We show that, for gauge couplings smaller
than $0.4$, the LHC gives rise to the strongest collider limit. In particular,
we find $M_{Z^{\prime}}/g_{BL} > 8.7$ TeV for $g_{BL}=0.3$. We conclude that
the NLO+NLL corrections improve the dilepton bounds on the $Z^{\prime}$ mass
and that both dark matter candidates are only viable in the $Z^{\prime}$
resonance region, with the parameter space for scalar dark matter being fully
probed by XENON1T. Lastly, we show that one can successfully have a minimal two
component dark matter model.


title:
Broken symmetry dielectric resonators for high quality-factor Fano
  metasurfaces

abstract:
  We present a new approach to dielectric metasurface design that relies on a
single resonator per unit cell and produces robust, high quality-factor Fano
resonances. Our approach utilizes symmetry breaking of highly symmetric
resonator geoemetries, such as cubes, to induce couplings between the otherwise
orthogonal resonator modes. In particular, we design perturbations that couple
"bright" dipole modes to "dark" dipole modes whose radiative decay is
suppressed by local field effects in the array. Our approach is widely scalable
from the near-infrared to radio frequencies. We first unravel the Fano
resonance behavior through numerical simulations of a germanium resonator-based
metasurface that achieved a quality-factor of ~1300 at ~10.8 um. Then, we
present two experimental demonstrations operating in the near-infrared (~1 um):
a silicon-based implementation that achieved a quality-factor of ~350; and a
gallium arsenide-based structure that achieves a quality-factor of ~600 - the
highest near-infrared quality-factor experimentally demonstrated to date with
this kind of metasurfaces. Importantly, large electromagnetic field
enhancements appear within the resonators at the Fano resonant frequencies. We
envision that combining high-quality factor, high field enhancement resonances
with nonlinear and active/gain materials such as gallium arsenide will lead to
new classes of active optical devices.


title: Perpendicular magnetic anisotropy of two-dimensional Rashba ferromagnets

abstract:
  We compute the magnetocrystalline anisotropy energy within two-dimensional
Rashba models. For a ferromagnetic free-electron Rashba model, the magnetic
anisotropy is exactly zero regardless of the strength of the Rashba coupling,
unless only the lowest band is occupied. For this latter case, the model
predicts in-plane anisotropy. For a more realistic Rashba model with finite
band width, the magnetic anisotropy evolves from in-plane to perpendicular and
back to in-plane as bands are progressively filled. This evolution agrees with
first-principles calculations on the interfacial anisotropy, suggesting that
the Rashba model captures energetics leading to anisotropy originating from the
interface provided that the model takes account of the finite Brillouin zone.
The results show that the electron density modulation by doping or an external
voltage is more important for voltage-controlled magnetic anisotropy than the
modulation of the Rashba parameter.


title:
The MIXR sample: AGN activity versus star formation across the
  cross-correlation of WISE, 3XMM, and FIRST/NVSS

abstract:
  We cross-correlate the largest available Mid-Infrared (WISE), X-ray (3XMM)
and Radio (FIRST+NVSS) catalogues to define the MIXR sample of AGN and
star-forming galaxies. We pre-classify the sources based on their positions on
the WISE colour/colour plot, showing that the MIXR triple selection is
extremely effective to diagnose the star formation and AGN activity of
individual populations, even on a flux/magnitude basis, extending the
diagnostics to objects with luminosities and redshifts from SDSS DR12. We
recover the radio/mid-IR star formation correlation with great accuracy, and
use it to classify our sources, based on their activity, as radio-loud and
radio-quiet AGN, LERGs/LINERs, and non-AGN galaxies. These diagnostics can
prove extremely useful for large AGN and galaxy samples, and help develop ways
to efficiently triage sources when data from the next generation of instruments
becomes available. We study bias in detail, and show that while the widely-used
WISE colour selections for AGN are very successful at cleanly selecting samples
of luminous AGN, they miss or misclassify a substantial fraction of AGN at
lower luminosities and/or higher redshifts. MIXR also allows us to test the
relation between radiative and kinetic (jet) power in radio-loud AGN, for which
a tight correlation is expected due to a mutual dependence on accretion. Our
results highlight that long-term AGN variability, jet regulation, and other
factors affecting the $Q/L$$_{bol}$ relation, are introducing a vast amount of
scatter in this relation, with dramatic potential consequences on our current
understanding of AGN feedback and its effect on star formation.


title:
Quasar-driven outflows account for the missing extragalactic gamma-ray
  background

abstract:
  The origin of the extragalactic $\gamma$-ray background permeating throughout
the Universe remains a mystery forty years after its discovery. The
extrapolated population of blazars can account for only half of the background
radiation at the energy range of ~ 0.1-10 GeV. Here we show that quasar-driven
outflows generate relativistic protons that produce the missing component of
the extragalactic $\gamma$-ray background and naturally match its spectral
fingerprint, with a generic break above ~ 1 GeV. The associated $\gamma$-ray
sources are too faint to be detected individually, explaining why they had not
been identified so far. However, future radio observations may image their
shock fronts directly. Our best fit to the Fermi-LAT observations of
extragalactic $\gamma$-ray background spectrum provides constraints on the
outflow parameters that agree with observations of these outflows and
theoretical predictions.


title:
Optimizing Variational Quantum Algorithms using Pontryagin's Minimum
  Principle

abstract:
  We use Pontryagin's minimum principle to optimize variational quantum
algorithms. We show that for a fixed computation time, the optimal evolution
has a bang-bang (square pulse) form, both for closed and open quantum systems
with Markovian decoherence. Our findings support the choice of evolution ansatz
in the recently proposed Quantum Approximate Optimization Algorithm. Focusing
on the Sherrington-Kirkpatrick spin-glass as an example, we find a system-size
independent distribution of the duration of pulses, with characteristic time
scale set by the inverse of the coupling constants in the Hamiltonian. The
optimality of the bang-bang protocols and the characteristic time scale of the
pulses provide an efficient parameterization of the protocol and inform the
search for effective hybrid (classical and quantum) schemes for tackling
combinatorial optimization problems. For the particular systems we study, we
find numerically that the optimal nonadiabatic bang-bang protocols outperform
conventional quantum annealing in the presence of weak white additive external
noise and weak coupling to a thermal bath modeled with the Redfield master
equation.


title:
Non-associativity in non-geometric string and M-theory backgrounds, the
  algebra of octonions, and missing momentum modes

abstract:
  We propose a non-associative phase space algebra for M-theory backgrounds
with locally non-geometric fluxes based on the non-associative algebra of
octonions. Our proposal is based on the observation that the non-associative
algebra of the non-geometric R-flux background in string theory can be obtained
by a proper contraction of the simple Malcev algebra generated by imaginary
octonions. Furthermore, by studying a toy model of a four-dimensional locally
non-geometric M-theory background which is dual to a twisted torus, we show
that the non-geometric background is "missing" a momentum mode. The resulting
seven-dimensional phase space can thus be naturally identified with the
imaginary octonions. This allows us to interpret the full uncontracted algebra
of imaginary octonions as the uplift of the string theory R-flux algebra to
M-theory, with the contraction parameter playing the role of the string
coupling constant $g_s$.


title: The large D black hole Membrane Paradigm at first subleading order

abstract:
  In the large D limit, and under certain circumstances, it has recently been
demonstrated that black hole dynamics in asymptotically flat spacetime reduces
to the dynamics of a non gravitational membrane propagating in flat D
dimensional spacetime. We demonstrate that this correspondence extends to all
orders in a 1/D expansion and outline a systematic method for deriving the
corrected membrane equation in a power series expansion in 1/D. As an
illustration of our method we determine the first subleading corrections to the
membrane equations of motion. A qualitatively new effect at this order is that
the divergence of the membrane velocity is nonzero and proportional to the
square of the shear tensor reminiscent of the entropy current of hydrodynamics.
As a test, we use our modified membrane equations to compute the corrections to
frequencies of light quasinormal modes about the Schwarzschild black hole and
find a perfect match with earlier computations performed directly in the
gravitational bulk.


title: Cumulative neutrino background from quasar-driven outflows

abstract:
  Quasar-driven outflows naturally account for the missing component of the
extragalactic $\gamma$-ray background through neutral pion production in
interactions between protons accelerated by the forward outflow shock and
interstellar protons. We study the simultaneous neutrino emission by the same
protons. We adopt outflow parameters that best fit the extragalactic
$\gamma$-ray background data and derive a cumulative neutrino background of
$\sim10^{-7}\,\rm GeV\,cm^{-2}\,s^{-1}\,sr^{-1}$ at neutrino energies
$E_{\nu}\gtrsim 10$ TeV, which naturally explains the most recent IceCube data
without tuning any free parameters. The link between the $\gamma$-ray and
neutrino emission from quasar outflows can be used to constrain the high-energy
physics of strong shocks at cosmological distances.


title:
Perturbation-Free Prediction of Resonance-Assisted Tunneling in Mixed
  Regular--Chaotic Systems

abstract:
  For generic Hamiltonian systems we derive predictions for dynamical tunneling
from regular to chaotic phase-space regions. In contrast to previous
approaches, we account for the resonance-assisted enhancement of
regular-to-chaotic tunneling in a non-perturbative way. This provides the
foundation for future semiclassical complex-path evaluations of
resonance-assisted regular-to-chaotic tunneling. Our approach is based on a new
class of integrable approximations which mimic the regular phase-space region
and its dominant nonlinear resonance chain in a mixed regular--chaotic system.
We illustrate the method for the standard map.


title:
A second-order, perfectly matched layer formulation to model 3D
  transient wave propagation in anisotropic elastic media

abstract:
  Numerical simulation of wave propagation in an infinite medium is made
possible by surrounding a finite region by a perfectly matched layer (PML).
Using this approach a generalized three-dimensional (3D) formulation is
proposed for time-domain modeling of elastic wave propagation in an unbounded
lossless anisotropic medium. The formulation is based on a second-order
approach that has the advantages of, physical relationship to the underlying
equations, and amenability to be implemented in common numerical schemes.
Specifically, our formulation uses three second-order equations of the
displacement field and nine auxiliary equations, along with the three time
histories of the displacement field. The properties of the PML, which are
controlled by a complex two-parameter stretch function, are such that it acts
as near perfect absorber. Using finite element method (FEM) 3D numerical
results are presented for a highly anisotropic medium. An extension of the
formulation to the particular case of a Kelvin-Vogit viscoelastic medium is
also presented.


title:
The cold dark matter content of Galactic dwarf spheroidals: no cores, no
  failures, no problem

abstract:
  We examine the dark matter content of satellite galaxies in Lambda-CDM
cosmological hydrodynamical simulations of the Local Group from the APOSTLE
project. We find excellent agreement between simulation results and estimates
for the 9 brightest Galactic dwarf spheroidals (dSphs) derived from their
stellar velocity dispersions and half-light radii. Tidal stripping plays an
important role by gradually removing dark matter from the outside in, affecting
in particular fainter satellites and systems of larger-than-average size for
their luminosity. Our models suggest that tides have significantly reduced the
dark matter content of Can Ven I, Sextans, Carina, and Fornax, a prediction
that may be tested by comparing them with field galaxies of matching luminosity
and size. Uncertainties in observational estimates of the dark matter content
of individual dwarfs have been underestimated in the past, at times
substantially. We use our improved estimates to revisit the `too-big-to-fail'
problem highlighted in earlier N-body work. We reinforce and extend our
previous conclusion that the APOSTLE simulations show no sign of this problem.
The resolution does not require `cores' in the dark mass profiles, but, rather,
relies on revising assumptions and uncertainties in the interpretation of
observational data and accounting for `baryon effects' in the theoretical
modelling.


title: Very-high energy emission from pulsars

abstract:
  The vast majority of pulsars detected by the Fermi Large Area Telescope (LAT)
display exponentially cutoff spectra with cutoffs falling in a narrow band
around a few GeV. Early spectral modelling predicted spectral cutoffs at
energies of up to 100 GeV, assuming curvature radiation. It was therefore not
expected that pulsars would be visible in the very-high energy (VHE) regime
(>100 GeV). The VERITAS announcement of the detection of pulsed emission from
the Crab pulsar at energies up to 400 GeV (and now up to 1.5 TeV as detected by
MAGIC) therefore raised important questions about our understanding of the
electrodynamics and local environment of pulsars. H.E.S.S. has now detected
pulsed emission from the Vela pulsar down to tens of GeV, making this the
second pulsar detected by a ground-based Cherenkov telescope. Deep upper limits
have also been obtained by VERITAS and MAGIC for the Geminga pulsar. We will
review the latest developments in VHE pulsar science, including an overview of
the latest observations, refinements, and extensions to radiation models and
magnetic field structures, and the implementation of new radiation mechanisms.
This will assist us in understanding the VHE emission detected from the Crab
pulsar, and predicting the level of VHE emission expected from other pulsars,
which is very important for the upcoming CTA.


title:
About AGN ionization echoes, thermal echoes, and ionization deficits in
  low redshift Lyman-alpha blobs

abstract:
  We report the discovery of 14 Lyman-alpha blobs (LABs) at z~0.3, existing at
least 4-7 billion years later in the Universe than all other LABs known. Their
optical diameters are 20-70 kpc, and GALEX data imply Ly-alpha luminosities of
(0.4-6.3)x10^43 erg/s. Contrary to high-z LABs, they live in low-density areas.
They are ionized by AGN, suggesting that cold accretion streams as a power
source must deplete between z=2 and z=0.3. We also show that transient AGN
naturally explain the ionization deficits observed in many LABs: Their Ly-alpha
and X-ray fluxes decorrelate below 10^6 years because of the delayed escape of
resonantly scattering Ly-alpha photons. High Ly-alpha luminosities do not
require currently powerful AGN, independent of obscuration. Chandra X-ray data
reveal intrinsically weak AGN, confirming the luminous optical nebulae as
impressive ionization echoes. For the first time, we also report mid-infrared
thermal echoes from the dusty tori. We conclude that the AGN have faded by 3-4
orders of magnitude within the last 10^(4-5) years, leaving fossil UV, optical
and thermal radiation behind. The host galaxies belong to the group of
previously discovered Green Bean galaxies (GBs). Gemini optical imaging reveals
smooth spheres, mergers, spectacular outflows and ionization cones. Because of
their proximity and high flux densities, GBs are perfect targets to study AGN
feedback, mode switching and the Ly-alpha escape. The fully calibrated, coadded
optical FITS images are publicly available.


title: Studies of the Long Secondary Periods in Pulsating Red Giants

abstract:
  We have used systematic, sustained visual observations from the AAVSO
International Database, and the AAVSO time-series analysis package VSTAR to
study the unexplained "long secondary periods" (LSPs) in 27 pulsating red
giants. In our sample, the LSPs range from 479 to 2967 days, and are on average
8.1 +/- 1.3 times the pulsation period. There is no evidence for more than one
LSP in each star. In stars with both the fundamental and first overtone radial
period present, the LSP is more often about 10 times the latter. The visual
amplitudes of the LSPs are typically 0.1 magnitude and do not correlate with
the LSP. The phase curves tend to be sinusoidal, but at least two are sawtooth.
The LSPs are stable, within their errors, over the timespan of our data, which
is typically 25,000 days. The amplitudes, however, vary by up to a factor of
two or more on a timescale of roughly 20-30 LSPs. There is no obvious
difference between the behavior of the carbon (C) stars and the normal oxygen
(M) stars. Previous multicolor photoelectric observations showed that the LSP
color variations are similar to those of the pulsation period, and of the LSPs
in the Magellanic Clouds, and not like those of eclipsing stars. We note that
the LSPs are similar to the estimated rotation periods of the stars, though the
latter have large uncertainties. This suggests that the LSP phenomenon may be a
form of modulated rotational variability.


title:
Dirichlet parabolicity and $L^1$-Liouville property under localized
  geometric conditions

abstract:
  We shed a new light on the $L^1$-Liouville property for positive,
superharmonic functions by providing many evidences that its validity relies on
geometric conditions localized on large enough portions of the space. We also
present examples in any dimension showing that the $L^1$-Liouville property is
strictly weaker than the stochastic completeness of the manifold. The main tool
in our investigations is represented by the potential theory of a manifold with
boundary subject to Dirichlet boundary conditions. The paper incorporates,
under a unifying viewpoint, some old and new aspects of the theory, with a
special emphasis on global maximum principles and on the role of the Dirichlet
Green's kernel.


title: Fermionic observables in the transverse Ising chain

abstract:
  We introduce a notion of s-holomorphicity suitable for certain quantum spin
systems in one dimension, and define two observables in the critical
transverse-field Ising model which have this property. The observables are
defined using graphical representations in the complex plane, and are analogous
to Smirnov's FK-Ising and spin-Ising observables, respectively. We also briefly
discuss scaling-limits of these observables.


title:
Precision velocimetry planet hunting with PARAS: Current performance and
  lessons to inform future extreme precision radial velocity instruments

abstract:
  PARAS is a fiber-fed stabilized high-resolution cross-dispersed echelle
spectrograph, located on the 1.2 m telescope in Mt. Abu India. Designed for
exoplanet detection, PARAS is capable of single-shot spectral coverage of 3800
- 9600 A, and currently achieving radial velocity (RV) precisions approaching
~1 m/s over several months using simultaneous ThAr calibration. As such, it is
one of the few dedicated stabilized fiber-fed spectrographs on small (1-2 m)
telescopes that are able to fill an important niche in RV follow-up and stellar
characterization. The success of ground-based RV surveys is motivating the push
into extreme precisions, with goals of ~10 cm/s in the optical and <1 m/s in
the near-infrared (NIR). Lessons from existing instruments like PARAS are
invaluable in informing hardware design, providing pipeline prototypes, and
guiding scientific surveys. Here we present our current precision estimates of
PARAS based on observations of bright RV standard stars, and describe the
evolution of the data reduction and RV analysis pipeline as instrument
characterization progresses and we gather longer baselines of data. Secondly,
we discuss how our experience with PARAS is a critical component in the
development of future cutting edge instruments like (1) the Habitable Zone
Planet Finder (HPF), a NIR spectrograph optimized to look for planets around M
dwarfs, scheduled to be commissioned on the Hobby Eberly Telescope in 2017, and
(2) the NEID optical spectrograph, designed in response to the NN-EXPLORE call
for an extreme precision Doppler spectrometer (EPDS) for the WIYN telescope. In
anticipation of instruments like TESS and GAIA, the ground-based RV support
system is being reinforced. We emphasize that instruments like PARAS will play
an intrinsic role in providing both complementary follow-up and battlefront
experience for these next generation of precision velocimeters.


title: Position Dependent Mass Approach and Quantization for a Torus Lagrangian

abstract:
  We have shown that a Lagrangian for a torus surface can yield second order
nonlinear differential equations using the Euler-Lagrange formulation. It is
seen that these second order nonlinear differential equations can be
transformed into the nonlinear quadratic and Mathews-Lakshmanan equations using
the position dependent mass approach developed by Mustafa for the classical
systems. Then, we have applied the quantization procedure to the nonlinear
quadratic and Mathews-Lakshmanan equations and found their exact solutions.


title:
Radial Velocity Fitting Challenge. I. Simulating the data set including
  realistic stellar radial-velocity signals

abstract:
  Stellar signals are the main limitation for precise radial-velocity (RV)
measurements. These signals arise from the photosphere of the stars. The m/s
perturbation created by these signals prevents the detection and mass
characterization of small-mass planetary candidates such as Earth-twins.
Several methods have been proposed to mitigate stellar signals in RV
measurements. However, without precisely knowing the stellar and planetary
signals in real observations, it is extremely difficult to test the efficiency
of these methods.
  The goal of the RV fitting challenge is to generate simulated RV data
including stellar and planetary signals and to perform a blind test within the
community to test the efficiency of the different methods proposed to recover
planetary signals despite stellar signals.
  In this first paper, we describe the simulation used to model the
measurements of the RV fitting challenge. Each simulated planetary system
includes the signals from instrumental noise, stellar oscillations,
granulation, supergranulation, stellar activity, and observed and simulated
planetary systems. In addition to RV variations, this simulation also models
the effects of instrumental noise and stellar signals on activity observables
obtained by HARPS-type high-resolution spectrographs, that is, the calcium
activity index log(R'hk) and the bisector span and full width at half maximum
of the cross-correlation function.
  We publish the 15 systems used for the RV fitting challenge including the
details about the planetary systems that were injected into each of them (data
available at CDS and here: https://rv-challenge.wikispaces.com.


title: Global Energetics of Solar Flares: III. Non thermal Energies

abstract:
  This study entails the third part of a global flare energetics project, in
which Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) data of 191 M and
X-class flare events from the first 3.5 yrs of the Solar Dynamics Observatory
(SDO) mission are analyzed. We fit a thermal and a nonthermal component to
RHESSI spectra, yielding the temperature of the differential emission measure
(DEM) tail, the nonthermal power law slope and flux, and the thermal/nonthermal
cross-over energy $e_{\mathrm{co}}$. From these parameters we calculate the
total nonthermal energy $E_{\mathrm{nt}}$ in electrons with two different
methods: (i) using the observed cross-over energy $e_{\mathrm{co}}$ as
low-energy cutoff, and (ii) using the low-energy cutoff $e_{\mathrm{wt}}$
predicted by the warm thick-target bremsstrahlung model of Kontar et al. {\bf
Based on a mean temperature of $T_e=8.6$ MK in active regions we find
low-energy cutoff energies of $e_{\mathrm{wt}} =6.2\pm 1.6$ keV for the
warm-target model, which is significantly lower than the cross-over energies
$e_{\mathrm{co}}=21 \pm 6$ keV. Comparing with the statistics of magnetically
dissipated energies $E_{\mathrm{mag}}$ and thermal energies $E_{\mathrm{th}}$
from the two previous studies, we find the following mean (logarithmic) energy
ratios with the warm-target model: $E_{\mathrm{nt}} = 0.41 \ E_{\mathrm{mag}}$,
$E_{\mathrm{th}} = 0.08 \ E_{\mathrm{mag}}$, and $E_{\mathrm{th}} = 0.15 \
E_{\mathrm{nt}}$. The total dissipated magnetic energy exceeds the thermal
energy in 95% and the nonthermal energy in 71% of the flare events, which
confirms that magnetic reconnection processes are sufficient to explain flare
energies. The nonthermal energy exceeds the thermal energy in 85\% of the
events, which largely confirms the warm thick-target model.


title:
Interplay between BCS and Mott physics in the phenomenon of high-$T_c$
  superconductivity

abstract:
  Superconducting electron systems of solids hosting flat bands are studied,
with a view to improved understanding of the fundamental physics giving rise to
high-temperature superconductivity. We present a modified form of the set of
Gor'kov equations of BCS theory that incorporates a Mott-like gap in the
single-particle spectrum. Such a quantity is emergent in systems with flat
bands having interactions repulsive in the Cooper channel, provided
particle-hole symmetry is broken. The equations so obtained are applied to the
elucidation of features of the two-gap structure of single-particle spectra of
underdoped high-$T_c$ superconductors, as revealed in angle-resolved
photoemission spectrometry.


title: Darboux tranformation and solutions of some integrable systems

abstract:
  The relation between the Darboux transformation and the solutions of the full
Kostant Toda lattice is analyzed. The discrete Korteweg de Vries equation is
used to obtain such solutions and the main result of [1] is extended to the
case of general (p + 2)-banded Hessenberg matrices.


title:
Radiation and Polarization Signatures of 3D Multi-zone Time-dependent
  Hadronic Blazar Model

abstract:
  We present a newly developed time-dependent three-dimensional multi-zone
hadronic blazar emission model. By coupling a Fokker-Planck based
lepto-hadronic particle evolution code 3DHad with a polarization-dependent
radiation transfer code, 3DPol, we are able to study the time-dependent
radiation and polarization signatures of a hadronic blazar model for the first
time. Our current code is limited to parameter regimes in which the hadronic
$\gamma$-ray output is dominated by proton synchrotron emission, neglecting
pion production. Our results demonstrate that the time-dependent flux and
polarization signatures are generally dominated by the relation between the
synchrotron cooling and the light crossing time scale, which is largely
independent of the exact model parameters. We find that unlike the low-energy
polarization signatures, which can vary rapidly in time, the high-energy
polarization signatures appear stable. As a result, future high-energy
polarimeters may be able to distinguish such signatures from the lower and more
rapidly variable polarization signatures expected in leptonic models.


title:
Cloaking an arbitrary object via anomalous localized resonance: the
  cloak is independent of the object

abstract:
  In this paper, we present various schemes of cloaking an arbitrary objects
via anomalous localized resonance and provide their analysis in two and three
dimensions. This is a way to cloak an object using negative index materials in
which the cloaking device is independent of the object. As a result, we show
that in two dimensional quasistatic regime an annular plasmonic structure $-I$
cloaks small but finite size objects near by. We also discuss its connections
with superlensing and cloaking using complementary media. In particular, we
confirm the possibility that a lens can act like a cloak and conversely. This
possibility was raised about a decade ago in the literature.


title:
Partition function on spheres: how (not) to use zeta function
  regularization

abstract:
  It is known that not all summation methods are linear and stable. Zeta
function regularization is in general non-linear. However, in some cases formal
manipulations with "zeta function" regularization (assuming linearity of sums)
lead to correct results. We consider several examples and show why this
happens.


title: Stochastic Control via Entropy Compression

abstract:
  We consider an agent trying to bring a system to an acceptable state by
repeated probabilistic action. Several recent works on algorithmizations of the
Lovasz Local Lemma (LLL) can be seen as establishing sufficient conditions for
the agent to succeed. Here we study whether such stochastic control is also
possible in a noisy environment, where both the process of state-observation
and the process of state-evolution are subject to adversarial perturbation
(noise). The introduction of noise causes the tools developed for LLL
algorithmization to break down since the key LLL ingredient, the sparsity of
the causality (dependence) relationship, no longer holds. To overcome this
challenge we develop a new analysis where entropy plays a central role, both to
measure the rate at which progress towards an acceptable state is made and the
rate at which noise undoes this progress. The end result is a sufficient
condition that allows a smooth tradeoff between the intensity of the noise and
the amenability of the system, recovering an asymmetric LLL condition in the
noiseless case.


title:
Measurement of the forward Z boson production cross-section in pp
  collisions at $\sqrt{s} = 13$ TeV

abstract:
  A measurement of the production cross-section of Z bosons in pp collisions at
$\sqrt{s} = 13$ TeV is presented using dimuon and dielectron final states in
LHCb data. The cross-section is measured for leptons with pseudorapidities in
the range $2.0 < \eta < 4.5$, transverse momenta $p_\text{T} > 20$ GeV and
dilepton invariant mass in the range $60<m(\ell\ell)<120$ GeV. The integrated
cross-section from averaging the two final states is
\begin{equation*}\sigma_{\text{Z}}^{\ell\ell} = 194.3 \pm 0.9 \pm 3.3 \pm
7.6\text{ pb,}\end{equation*} where the first uncertainty is statistical, the
second is due to systematic effects, and the third is due to the luminosity
determination. In addition, differential cross-sections are measured as
functions of the Z boson rapidity, transverse momentum and the angular variable
$\phi^*_\eta$.


title:
High contrast imaging of exoplanets on ELTs using a super-Nyquist
  wavefront control scheme

abstract:
  One of the key science goals for extremely large telescopes (ELTs) is the
detailed characterization of already known directly imaged exoplanets. The
typical adaptive optics (AO) Nyquist control region for ELTs is ~0.4
arcseconds, placing many already known directly imaged planets outside the DM
control region and not allowing any standard wavefront control scheme to remove
speckles that would allow higher SNR images/spectra to be acquired. This can be
fixed with super-Nyquist wavefront control (SNWFC), using a sine wave phase
plate to allow for wavefront control outside the central DM Nyquist region. We
demonstrate that SNWFC is feasible through a simple, deterministic,
non-coronagraphic, super-Nyquist speckle nulling technique in the adaptive
optics laboratory at the National Research Council of Canada. We also present
results in simulation of how SNWFC using the self coherent camera (SCC) can be
used for high contrast imaging. This technique could be implemented on future
high contrast imaging instruments to improve contrast outside the standard
central dark hole for higher SNR characterization of exoplanets.


title:
Disappearence of the Aharonov-Bohm Effect for Interacting Electrons in a
  ZnO Quantum Ring

abstract:
  The electronic states and optical transitions of a ZnO quantum ring
containing few interacting electrons in an applied magnetic field are found to
be very different from those in a conventional semiconductor system, such as a
GaAs ring. The strong Zeeman and Coulomb interaction of the ZnO system, exert a
profound influence on the electron states and on the optical properties of the
ring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in
a ZnO quantum ring strongly depends on the electron number. In fact, for two
electrons in the ZnO ring, the AB oscillations become aperiodic, while for
three electrons (interacting) the AB oscillations completely disappear.
Therefore, unlike in conventional quantum ring topology, here the AB effect
(and the resulting persistent current) can be controlled by varying the
electron number.


title: On the Semi-Classical Brownian Bridge Measure

abstract:
  We prove an integration by parts formula for the probability measure induced
by the semi-classical Riemmanian Brownian bridge over a manifold with a pole.


title:
Vacuum polarization and quadrupole corrections to the hyperfine
  splitting of P-states in muonic deuterium

abstract:
  On the basis of quasipotential approach in quantum electrodynamics we
calculate vacuum polarization and quadrupole corrections in first and second
orders of perturbation theory in hyperfine structure of P-states in muonic
deuterium. All corrections are presented in integral form and evaluated
analytically and numerically. The obtained results can be used for the
improvement of the transition frequencies between levels 2P and 2S.


title:
One Loop Mass Renormalization of Unstable Particles in Superstring
  Theory

abstract:
  Most of the massive states in superstring theory are expected to undergo mass
renormalization at one loop order. Typically these corrections should contain
imaginary parts, indicating that the states are unstable against decay into
lighter particles. However in such cases, direct computation of the
renormalized mass using superstring perturbation theory yields divergent
result. Previous approaches to this problem involve various analytic
continuation techniques, or deforming the integral over the moduli space of the
torus with two punctures into the complexified moduli space near the boundary.
In this paper we use insights from string field theory to describe a different
approach that gives manifestly finite result for the mass shift satisfying
unitarity relations. The procedure is applicable to all states of
(compactified) type II and heterotic string theories. We illustrate this by
computing the one loop correction to the mass of the first massive state on the
leading Regge trajectory in SO(32) heterotic string theory.


title: Momentum Evolution Numerics of an Impurity in a Quantum Quench

abstract:
  A discussion on the momentum evolution of an impurity interacting via a
finite delta potential repulsion with a non-interacting fermionic background
gas is presented. It has recently been shown that the momentum evolution of
this system displays two interesting features, namely a non-zero thermalised
value and a long-lived quantum mechanical oscillation around this plateau named
"quantum flutter" [Mathy, Zvonarev, Demler, Nat. Phys. 2012]. We discuss
revivals in the momentum of the impurity, which have been seen before but not
yet thoroughly investigated. Subsequently it is shown the quantum flutter and
revivals are caused by disjoint sets of eigenstate transitions, and this fact
is used to interpret some of their aspects. This attribution of momentum
features to different eigenstate subsets allows quantitative reproduction of
these features with much less computational expense than has so far been
possible. Finally some results on the distribution of the momentum of
eigenstates and their relation to the momentum of the impurity once the system
has been thermalised are presented along with a discussion on the time averaged
infinite time value of the momentum and its comparison to different eigenstate
subsets.