title: New representations for $\sigma(q)$ via reciprocity theorems

abstract:
  Two new representations for Ramanujan's function $\sigma(q)$ are obtained.
The proof of the first one uses the three-variable reciprocity theorem due to
Soon-Yi Kang and a transformation due to R.P. Agarwal while that of the second
uses the four-variable reciprocity theorem due to George Andrews and a
generalization of a recent transformation of Andrews, Schultz, Yee and the
second author. The advantage of these representations is that they involve free
complex parameters - one in the first representation, and two in the second.


title:
A Central Compact Object in Kes 79: The hypercritical regime and
  neutrino expectation

abstract:
  We present magnetohydrodynamical simulations of a strong accretion onto
magnetized proto-neutron stars for the Kesteven 79 (Kes 79) scenario. The
supernova remnant Kes 79, observed with the Chandra ACIS-I instrument during
approximately 8.3 h, is located in the constellation Aquila at a distance of
7.1 kpc in the galactic plane. It is a galactic and a very young object with an
estimate age of 6 kyr. The Chandra image has revealed, for the first time, a
point-like source at the center of the remnant. The Kes 79 compact remnant
belongs to a special class of objects, the so-called Central Compact Objects,
which exhibits no evidence for a surrounding pulsar wind nebula. In this work
we show that the submergence of the magnetic field during the hypercritical
phase can explain such behavior for Kes 79 and others CCOs. The simulations of
such regime were carried out with the adaptive-mesh-refinement code FLASH in
two spatial dimensions, including radiative loss by neutrinos and an adequate
equation of state for such regime. From the simulations, we estimate that the
number of thermal neutrinos expected on the Hyper-Kamiokande Experiment is
733$\pm$364. In addition, we compute the flavor ratio on Earth for a progenitor
model.


title: Time Reversal with Post-Equalization for OFDM without CP in Massive MIMO

abstract:
  This paper studies the possibility of eliminating the redundant cyclic prefix
(CP) of orthogonal frequency division multiplexing (OFDM) in massive
multiple-input multiple-output systems. The absence of CP increases the
bandwidth efficiency in expense of intersymbol interference (ISI) and
intercarrier interference (ICI). It is known that in massive MIMO, different
types of interference fade away as the number of base station (BS) antennas
tends to infinity. In this paper, we investigate if the channel distortions in
the absence of CP are averaged out in the large antenna regime. To this end, we
analytically study the performance of the conventional maximum ratio combining
(MRC) and realize that there always remains some residual interference leading
to saturation of signal to interference (SIR). This saturation of SIR is
quantified through mathematical equations. Moreover, to resolve the saturation
problem, we propose a technique based on time-reversal MRC with zero forcing
multiuser detection (TR-ZF). Thus, the SIR of our proposed TR-ZF does not
saturate and is a linear function of the number of BS antennas. We also show
that TR-ZF only needs one OFDM demodulator per user irrespective of the number
of BS antennas; reducing the BS signal processing complexity significantly.
Finally, we corroborate our claims as well as analytical results through
simulations.


title: Ghosts! A Location-Based Bluetooth LE Mobile Game for Museum Exploration

abstract:
  BLE (Bluetooth Low Energy) is a new wireless communication technology that,
thanks to reduced power consumption, promises to facilitate communication
between computing devices and help us harness their power in environments and
contexts previously untouched by information technology. Museums and other
facilities housing various cultural content are a particularly interesting area
of application. The University of Cambridge Museums consortium has put
considerable effort into researching the potential uses of emerging
technologies such as BLE to unlock new experiences enriching the way we engage
with cultural information. As a part of this research initiative, our ambition
has been to examine the challenges and opportunities introduced by the
introduction of a BLE-centred system into the museum context. We present an
assessment of the potential offered by this technology and of the design
approaches that might yield the best results when developing BLE-centred
experiences for museum environments. A pivotal part of our project consisted of
designing, developing and evaluating a prototype mobile location-based
BLE-centred game. A number of technical problems, such as unstable and
fluctuating signal strength, were encountered throughout the project lifecycle.
Instead of attempting to eliminate such problems, we argued in favour of
embracing them and turning them into a cornerstone of the gameplay. Our study
suggested that this alternative seamful design approach yields particularly
good results when deploying the technology in public environments. The project
outcome also demonstrated the potential of BLE-centred solutions to reach out
and engage new demographics, especially children, extending their interest in
museum visits.


title:
Knight shifts, nuclear spin-relaxation rates, and spin echo decay times
  in the pseudogap regime of the cuprates: Simulation and relation to
  experiment

abstract:
  We study the temperature and doping evolution of the NMR Knight shift, spin
relaxation rate, and spin echo decay time in the pseudogap regime of the
two-dimensional Hubbard model for parameters believed to be relevant to cuprate
superconductors using cluster dynamical mean field theory. We recover the
suppression of the Knight shift seen in experiment upon entering the pseudogap
regime and find agreement between single and two-particle measures of the
pseudogap onset temperature. The simulated spin-echo decay time shows a linear
in T behavior at high T which flattens off as T is lowered, and increases as
doping is increased. The relaxation rate shows a marked increase as T is
lowered but no indication of a pseudogap on the Cu site, and a clear downturn
on the O site, consistent with experimental results on single layer materials
but different from double layer materials. The consistency of the simulated
susceptibilities with experiment, along with similar agreement on the
single-particle level and the absence of long-range order and symmetry breaking
suggests that the pseudogap is well described by strong short-range correlation
effects and that long-range order and multi-orbital effects are not required.


title: Branch Point Twist Field Correlators in the Massive Free Boson Theory

abstract:
  Well-known measures of entanglement in one-dimensional many body quantum
systems, such as the entanglement entropy and the logarithmic negativity, may
be expressed in terms of the correlation functions of local fields known as
branch point twist fields in a replica quantum field theory. In this "replica"
approach the computation of measures of entanglement generally involves a
mathematically non-trivial analytic continuation in the number of replicas. In
this paper we consider two-point functions of twist fields and their analytic
continuation in the 1+1 dimensional massive (non-compactified) free Boson
theory. This is one of the few theories for which all matrix elements of twist
fields are known so that we may hope to compute correlation functions very
precisely. We study two particular two-point functions which are related to the
logarithmic negativity of semi-infinite disjoint intervals and to the
entanglement entropy of one interval. We show that our prescription for the
analytic continuation yields results which are in full agreement with conformal
field theory predictions in the short-distance limit. We provide numerical
estimates of universal quantities and their ratios, both in the massless (twist
field structure constants) and the massive (expectation values of twist fields)
theory. We find that particular ratios are given by divergent form factor
expansions. We propose such divergences stem from the presence of logarithmic
factors in addition to the expected power-law behaviour of two-point functions
at short-distances. Surprisingly, at criticality these corrections give rise to
a log(logL) correction to the entanglement entropy of one interval of length L.
This hitherto overlooked result is in agreement with results by Calabrese,
Cardy and Tonni and has been independently derived by Blondeau-Fournier and
Doyon (in preparation).


title:
Plasmonic Hot Electron Transport Driven Site-Specific Surface-Chemistry
  with Nanoscale Spatial Resolution

abstract:
  Nanoscale localization of electromagnetic fields near metallic nanostructures
underpins the fundamentals and applications of plasmonics. The unavoidable
energy loss from plasmon decay, initially seen as a detriment, has now expanded
the scope of plasmonic applications to exploit the generated hot carriers.
However, quantitative understanding of the spatial localization of these hot
carriers, akin to electromagnetic near-field maps, has been elusive. Here we
spatially map hot-electron-driven reduction chemistry with 15 nanometre
resolution as a function of time and electromagnetic field polarization for
different plasmonic nanostructures. We combine experiments employing a
six-electron photo-recycling process that modify the terminal group of a
self-assembled monolayer on plasmonic silver nanoantennas, with theoretical
predictions from first-principles calculations of non-equilibrium hot-carrier
transport in these systems. The resulting localization of reactive regions,
determined by hot carrier transport from high-field regions, paves the way for
hot-carrier extraction science and nanoscale regio-selective surface chemistry.


title: Robust high-fidelity DFT study of the lithium-graphite phase diagram

abstract:
  Graphite is the most widely used and among the most widely-studied anode
materials for lithium-ion batteries. With increasing demands on lithium
batteries to operate at lower temperatures and higher currents, it is crucial
to understand lithium intercalation in graphite due to issues associated with
lithium plating. Lithium intercalation into graphite has been extensively
studied theoretically using density functional theory (DFT) calculations,
complemented by experimental studies through X-ray diffraction, spectroscopy,
optical imaging and other techniques. In this work, we present a first
principles based model using DFT calculations, employing the BEEF-vdW as the
exchange correlation functional, and Ising model to determine the phase
transformations and subsequently, the thermodynamic intercalation potential
diagram. We explore a configurational phase space of about 1 billion structures
by accurately determining the important interactions for the Ising model. The
BEEF-vdW exchange correlation functional employed accurately captures a range
of interactions including vdW, covalent and ionic interactions. We incorporate
phonon contributions at finite temperatures and configurational entropy to get
high accuracy in free energy and potentials. We utilize the built-in error
estimation capabilities of the BEEF-vdW exchange correlation functional and to
develop a methodological framework for determining the uncertainty associated
with DFT calculated phase diagrams and intercalation potentials. The framework
also determines the confidence of each predicted stable phase. The confidence
value of a phase can help us to identify regions of solid solutions and phase
transformations accurately.


title:
Asymptotic profile of positive solutions of Lane-Emden problems in
  dimension two

abstract:
  We consider families $u_p$ of solutions to the problem
\begin{equation}\label{problemAbstract} \left\{\begin{array}{lr}-\Delta u= u^p
& \mbox{ in }\Omega\\ u>0 & \mbox{ in }\Omega\\ u=0 & \mbox{ on }\partial
\Omega \end{array}\right.\tag{$\mathcal E_p$} \end{equation} where $p>1$ and
$\Omega$ is a smooth bounded domain of $\mathbb R^2$. We give a complete
description of the asymptotic behavior of $u_p$ as $p\rightarrow +\infty$,
under the condition \[p\int_{\Omega} |\nabla u_p|^2\,dx\rightarrow
\beta\in\mathbb R\qquad\mbox{ as $p\rightarrow +\infty$}.\]


title:
A Comparison of Nineteen Various Electricity Consumption Forecasting
  Approaches and Practicing to Five Different Households in Turkey

abstract:
  The accuracy of the household electricity consumption forecast is vital in
taking better cost effective and energy efficient decisions. In order to design
accurate, proper and efficient forecasting model, characteristics of the series
have to been analyzed. The source of time series data comes from Online
Enerjisa System, the system of electrical energy provider in capital of Turkey,
which consumers can reach their latest two year period electricity
consumptions; in our study the period was May 2014 to May 2016. Various
techniques had been applied in order to analyze the data; classical
decomposition models; standard typed and also with the centering moving average
method, regression equations, exponential smoothing models and ARIMA models. In
our study, nine teen different approaches; all of these have at least
diversified aspects of methodology, had been compared and the best model for
forecasting were decided by considering the smallest values of MAPE, MAD and
MSD. As a first step we took the time period May 2014 to May 2016 and found
predicted value for June 2016 with the best forecasting model. After finding
the best forecasting model and fitted value for June 2016, than validating
process had been taken place; we made comparisons to see how well the real
value of June 2016 and forecasted value for that specific period matched.
Afterwards we made electrical consumption forecast for the following 3 months;
June-September 2016 for each of five households individually.


title:
Validating the effective-one-body model of spinning, precessing binary
  black holes against numerical relativity

abstract:
  In Ref. [1], the properties of the first gravitational wave detected by LIGO,
GW150914, were measured by employing an effective-one-body (EOB) model of
precessing binary black holes whose underlying dynamics and waveforms were
calibrated to numerical-relativity (NR) simulations. Here, we perform the first
extensive comparison of such EOBNR model to 70 precessing NR waveforms that
span mass ratios from 1 to 5, dimensionless spin magnitudes up to 0.5, generic
spin orientations, and length of about 20 orbits. We work in the observer's
inertial frame and include all $\ell=2$ modes in the gravitational-wave
polarizations. We introduce new prescriptions for the EOB ringdown signal
concerning its spectrum and time of onset. For total masses between 10Msun and
200Msun, we find that precessing EOBNR waveforms have unfaithfulness within
about 3% to NR waveforms when considering the Advanced-LIGO design noise curve.
This result is obtained without recalibration of the inspiral-plunge of the
underlying nonprecessing EOBNR model. The unfaithfulness is computed with
maximization over time and phase of arrival, sky location and polarization of
the EOBNR waveform and it is averaged over sky location and polarization of the
NR signal. We also present comparisons between NR and EOBNR waveforms in a
frame that tracks the orbital precession.


title:
Skewable matrices over $\wedge^2 V$ applied to locally metric
  connections

abstract:
  A necessary condition for a connection in a vector bundle to be locally
metric is for its curvature matrix, which consists of $2$ forms, to be skew
symmetric with respect to some local frame. In this paper we give a simple
algorithm that can be used to decide when a matrix of $2$ forms is equivalent
to a skew symmetric matrix. We apply this algorithm to verify whether a "{\it
full rank}" curvature connection is locally metric.


title: Converting entropy to curvature perturbations after a cosmic bounce

abstract:
  We study two-field bouncing cosmologies in which primordial perturbations are
created in either an ekpyrotic or a matter-dominated contraction phase. We use
a non-singular ghost condensate bounce model to follow the perturbations
through the bounce into the expanding phase of the universe. In contrast to the
adiabatic perturbations, which on large scales are conserved across the bounce,
entropy perturbations can grow significantly during the bounce phase. If they
are converted into adiabatic/curvature perturbations after the bounce, they
typically form the dominant contribution to the observed temperature
fluctuations in the microwave background, which can have several beneficial
implications. For ekpyrotic models, this mechanism loosens the constraints on
the amplitude of the ekpyrotic potential while naturally suppressing the
intrinsic amount of non-Gaussianity. For matter bounce models, the mechanism
amplifies the scalar perturbations compared to the associated primordial
gravitational waves.


title:
Interaction-Induced Weakening of Localization in Few-Particle Disordered
  Heisenberg Chains

abstract:
  We investigate real-space localization in the few-particle regime of the XXZ
spin-$1/2$ chain with a random magnetic field. Our investigation focuses on the
time evolution of the spatial variance of non-equilibrium densities, as
resulting for a specific class of initial states, namely, pure product states
of densely packed particles. Varying the strength of both particle-particle
interactions and disorder, we numerically calculate the long-time evolution of
the spatial variance $\sigma(t)$. For the two-particle case, the saturation of
this variance yields an increased but finite localization length, with a
parameter scaling different to known results for bosons. We find that this
interaction-induced increase is the stronger the more particles are taken into
account in the initial condition. We further find that our non-equilibrium
dynamics are clearly inconsistent with normal diffusion and instead point to
subdiffusive dynamics with $\sigma(t) \propto t^{1/4}$.


title:
A 2-D suspension of active agents: the role of fluid mediated
  interactions

abstract:
  Taking into account simultaneously the Vicsek short range ordering and also
the far-field hydrodynamic interactions mediated by the ambient fluid, we
investigate the role of long range interactions in the ordering phenomena in a
quasi 2-dimensional active suspension. By studying the number fluctuations, the
velocity correlation functions and cluster size distribution function, we
observe that depending on the number density of swimmers and the strength of
noise, the hydrodynamic interactions affect the ordering in a suspension. For a
fixed value of noise, at large density of particles, long range interactions
enhance the clustering in the system.


title: Trainable Frontend For Robust and Far-Field Keyword Spotting

abstract:
  Robust and far-field speech recognition is critical to enable true hands-free
communication. In far-field conditions, signals are attenuated due to distance.
To improve robustness to loudness variation, we introduce a novel frontend
called per-channel energy normalization (PCEN). The key ingredient of PCEN is
the use of an automatic gain control based dynamic compression to replace the
widely used static (such as log or root) compression. We evaluate PCEN on the
keyword spotting task. On our large rerecorded noisy and far-field eval sets,
we show that PCEN significantly improves recognition performance. Furthermore,
we model PCEN as neural network layers and optimize high-dimensional PCEN
parameters jointly with the keyword spotting acoustic model. The trained PCEN
frontend demonstrates significant further improvements without increasing model
complexity or inference-time cost.


title:
Scaling crossover in thin-film drag dynamics of fluid drops in the
  Hele-Shaw cell

abstract:
  We study both experimentally and theoretically the descending motion due to
gravity of a fluid drop surrounded by another immiscible fluid in a confined
space between two parallel plates, i.e., in the Hele-Shaw cell. As a result, we
show a new scaling regime of a nonlinear drag friction in viscous liquid that
replaces the well-known Stokes' drag friction through a clear collapse of
experimental data thanks to the scaling law. In the novel regime, the
dissipation in the liquid thin film formed between the drop and cell walls
governs the dynamics. The crossover of this scaling regime to another scaling
regime in which the dissipation inside the droplet is dominant is clearly
demonstrated and a phase diagram separating these scaling regimes is presented.


title: Stability for Borell-Brascamp-Lieb inequalities

abstract:
  We study stability issues for the so-called Borell-Brascamp-Lieb
inequalities, proving that when near equality is realized, the involved
functions must be $L^1$-close to be $p$-concave and to coincide up to
homotheties of their graphs.


title:
Highly mobile carriers in orthorhombic phases of iron-based
  superconductors FeSe${}_{1-x}$S${}_{x}$

abstract:
  The field and temperature dependencies of the longitudinal and Hall
resistivity have been measured for FeSe${}_{1-x}$S${}_{x}$ (x=0.04, 0.09 and
0.19) single crystals. The sample FeSe${}_{0.81}$S${}_{0.19}$ does not show a
transition to an orthorhombic phase and exhibits at low temperatures the
transport properties quite different from those of orthorhombic samples. The
behavior of FeSe${}_{0.81}$S${}_{0.19}$ is well described by the simple two
band model with comparable values of hole and electron mobility. In particular,
at low temperatures the transverse resistance shows a linear field dependence,
the magnetoresistance follow a quadratic field dependence and obeys to Kohler's
rule. In contrast, Kohler's rule is strongly violated for samples having an
orthorhombic low temperature structure. However, the transport properties of
the orthorhombic samples can be satisfactory described by the three band model
with the pair of almost equivalent to the tetragonal sample hole and electron
bands, supplemented with the highly mobile electron band which has two order
smaller carrier number. Therefore, the peculiarity of the low temperature
transport properties of the orthorhombic Fe(SeS) samples, as probably of many
other orthorhombic iron superconductors, is due to the presence of a small
number of highly mobile carriers which originate from the local regions of the
Fermi surface, presumably, nearby the Van Hove singularity points.


title:
Spacecraft observations and analytic theory of crescent-shaped electron
  distributions in asymmetric magnetic reconnection

abstract:
  Supported by a kinetic simulation, we derive an exclusion energy parameter
$\cal{E}_X$ providing a lower kinetic energy bound for an electron to cross
from one inflow region to the other during magnetic reconnection. As by a
Maxwell Demon, only high energy electrons are permitted to cross the inner
reconnection region, setting the electron distribution function observed along
the low density side separatrix during asymmetric reconnection. The analytic
model accounts for the two distinct flavors of crescent-shaped electron
distributions observed by spacecraft in a thin boundary layer along the low
density separatrix.


title: Stochastic Timed Games Revisited

abstract:
  Stochastic timed games (STGs), introduced by Bouyer and Forejt, naturally
generalize both continuous-time Markov chains and timed automata by providing a
partition of the locations between those controlled by two players (Player Box
and Player Diamond) with competing objectives and those governed by stochastic
laws. Depending on the number of players---$2$, $1$, or $0$---subclasses of
stochastic timed games are often classified as $2\frac{1}{2}$-player,
$1\frac{1}{2}$-player, and $\frac{1}{2}$-player games where the $\frac{1}{2}$
symbolizes the presence of the stochastic "nature" player. For STGs with
reachability objectives it is known that $1\frac{1}{2}$-player one-clock STGs
are decidable for qualitative objectives, and that $2\frac{1}{2}$-player
three-clock STGs are undecidable for quantitative reachability objectives. This
paper further refines the gap in this decidability spectrum. We show that
quantitative reachability objectives are already undecidable for $1\frac{1}{2}$
player four-clock STGs, and even under the time-bounded restriction for
$2\frac{1}{2}$-player five-clock STGs. We also obtain a class of
$1\frac{1}{2}$, $2\frac{1}{2}$ player STGs for which the quantitative
reachability problem is decidable.


title:
Hidden Order Signatures in the Antiferromagnetic Phase of
  U(Ru$_{1-x}$Fe$_x$)$_2$Si$_2$

abstract:
  We present a comprehensive set of elastic and inelastic neutron scattering
measurements on a range of Fe-doped samples of U(Ru$_{1-x}$Fe$_x$)$_2$Si$_2$
with 0.01~$\le~x~\le$~0.15. All of the samples measured exhibit long-range
antiferromagnetic order, with the size of the magnetic moment quickly
increasing to 0.51~$\mu_B$ at 2.5\% doping and continuing to increase
monotonically with doping, reaching 0.69~$\mu_B$ at 15\% doping. Time-of-flight
and inelastic triple-axis measurements show the existence of excitations at
(1~0~0) and (1.4~0~0) in all samples, which are also observed in the parent
compound. While the excitations in the 1\% doping are quantitatively identical
to the parent material, the gap and width of the excitations change rapidly at
2.5\% Fe doping and above. The 1\% doped sample shows evidence for a separation
in temperature between the hidden order and antiferromagnetic transitions,
suggesting that the antiferromagnetic state emerges at very low Fe dopings. The
combined neutron scattering data suggests not only discontinuous changes in the
magnetic moment and excitations between the hidden order and antiferromagnetic
phases, but that these changes continue to evolve up to at least $x$~=~0.15.


title:
$CH_{0}$-trivialit\'e universelle d'hypersurfaces cubiques presque
  diagonales

abstract:
  Toute hypersurface cubique lisse complexe de dimension au moins 2 dont
l'\'equation est donn\'ee par l'annulation d'une somme de formes cubiques \`a
variables s\'epar\'ees, chaque forme impliquant au plus trois variables, est
universellement $CH_{0}$-triviale.
  ---
  If a smooth cubic hypersurface of dimension at least 2 is defined by the
vanishing of a sum of cubic forms in independent variables and each of these
forms involves at most 3 variables, then the cubic hypersurface is universally
$CH_{0}$-trivial : there is an integral Chow decomposition of the diagonal.


title:
Spectral gap properties of the unitary groups: around Rider's results on
  non-commutative Sidon sets

abstract:
  We present a proof of Rider's unpublished result that the union of two Sidon
sets in the dual of a non-commutative compact group is Sidon, and that randomly
Sidon sets are Sidon. Most likely this proof is essentially the one announced
by Rider and communicated in a letter to the author around 1979 (lost by him
since then). The key fact is a spectral gap property with respect to certain
representations of the unitary groups $U(n)$ that holds uniformly over $n$. The
proof crucially uses Weyl's character formulae. We survey the results that we
obtained 30 years ago using Rider's unpublished results. Using a recent
different approach valid for certain orthonormal systems of matrix valued
functions, we give a new proof of the spectral gap property that is required to
show that the union of two Sidon sets is Sidon. The latter proof yields a
rather good quantitative estimate. Several related results are discussed with
possible applications to random matrix theory.


title: Set Reconstruction on the Hypercube

abstract:
  Given an action of a group $G$ on a set $S$, the $k$-deck of a subset $T$ of
$S$ is the multiset of all subsets of $T$ of size $k$, each given up to
translation by $G$. For a given subset $T$, the {\em reconstruction number} of
$T$ is the minimum $k$ such that the $k$-deck uniquely identifies $T$ up to
translation by $G$, and the {\em reconstruction number} of the action $G:S$ is
the maximum reconstruction number of any subset of $S$. The concept of
reconstruction number extends naturally to multisubsets $T$ of $S$ and
in~\cite{CPC:257539}, the author calculated the multiset-reconstruction number
of all finite abelian groups. In particular, it was shown that the
multiset-reconstruction number of $\mathbb{Z}_2^n$ was $n+1$. This provides an
upper bound of $n+1$ to the reconstruction number of $\mathbb{Z}_2^n$. The
author also showed a lower bound of $\lfloor{\frac{n+1}2}\rfloor$ in the same
paper. The purpose of this note is to close the gap. The reconstruction number
of $\mathbb{Z}_2^n$ is $\lfloor{n+1-\log_2(n+1-\log_2(n))}\rfloor.$


title: Magnetic anisotropy in the Kitaev model systems Na2IrO3 and RuCl3

abstract:
  We study the ordered moment direction in the extended Kitaev-Heisenberg model
relevant to honeycomb lattice magnets with strong spin-orbit coupling. We
utilize numerical diagonalization and analyze the exact cluster groundstates
using a particular set of spin coherent states, obtaining thereby quantum
corrections to the magnetic anisotropy beyond conventional perturbative
methods. It is found that the quantum fluctuations strongly modify the moment
direction obtained at a classical level, and are thus crucial for a precise
quantification of the interactions. The results show that the moment direction
is a sensitive probe of the model parameters in real materials. Focusing on the
experimentally relevant zigzag phases of the model, we analyze the currently
available neutron and resonant x-ray diffraction data on Na2IrO3 and RuCl3, and
discuss the parameter regimes plausible in these Kitaev-Heisenberg model
systems.


title: Is there a concordance value for $H_0$?

abstract:
  We test the theoretical predictions of several cosmological models against
different observables to compare the indirect estimates of the current
expansion rate of the Universe determined from model fitting with the direct
measurements based on Cepheids data published recently. We perform a
statistical analysis of type Ia supernova (SN Ia), Hubble parameter, and baryon
acoustic oscillation data. A joint analysis of these datasets allows us to
better constrain cosmological parameters, but also to break the degeneracy that
appears in the distance modulus definition between $H_0$ and the absolute
B-band magnitude of SN Ia, $M_0$. From the theoretical side, we considered
spatially flat and curvature-free $\Lambda$CDM, $w$CDM, and inhomogeneous
Lema\^{i}tre-Tolman-Bondi (LTB) models. To analyse SN Ia we took into account
the distributions of SN Ia intrinsic parameters. For the $\Lambda$CDM model we
find that $\Omega_m=0.35\pm0.02$, $H_0=(67.8\pm1.0)\,$km$\,$s$^{-1}/$Mpc, while
the corrected SN absolute magnitude has a normal distribution ${\cal
N}(19.13,0.11)$. The $w$CDM model provides the same value for $\Omega_m$, while
$H_0=(66.5\pm1.8)\,$km$\,$s$^{-1}/$Mpc and $w=-0.93\pm0.07$. When an
inhomogeneous LTB model is considered, the combined fit provides
$H_0=(64.2\pm1.9)\,$km$\,$s$^{-1}/$Mpc. Both the Akaike information criterion
and the Bayes factor analysis cannot clearly distinguish between $\Lambda$CDM
and $w$CDM cosmologies, while they clearly disfavour the LTB model. For the
$\Lambda$CDM, our joint analysis of the SN Ia, the Hubble parameter, and the
baryon acoustic oscillation datasets provides $H_0$ values that are consistent
with CMB-only Planck measurements, but they differ by $2.5\sigma$ from the
value based on Cepheids data.


title:
Uncertainty principles for inverse source problems, far field splitting
  and data completion

abstract:
  Starting with far field data of time-harmonic acoustic or electromagnetic
waves radiated by a collection of compactly supported sources in
two-dimensional free space, we develop criteria and algorithms for the recovery
of the far field components radiated by each of the individual sources, and the
simultaneous restoration of missing data segments. Although both parts of this
inverse problem are severely ill-conditioned in general, we give precise
conditions relating the wavelength, the diameters of the supports of the
individual source components and the distances between them, and the size of
the missing data segments, which guarantee that stable recovery in presence of
noise is possible. The only additional requirement is that a priori information
on the approximate location of the individual sources is available. We give
analytic and numerical examples to confirm the sharpness of our results and to
illustrate the performance of corresponding reconstruction algorithms, and we
discuss consequences for stability and resolution in inverse source and inverse
scattering problems.


title:
Entropy and Information of a harmonic oscillator in a time-varying
  electric field in 2D and 3D noncommutative spaces

abstract:
  We analyzed the noncommutativity effects on the Fisher information (F_(r,p))
and Shannon entropies (S_(r,p)) of a harmonic oscillator immersed in a
time-varying electric field in two and three dimensions. We find the exact
solutions of the respective time-dependent Schr\"odinger equation and use them
to calculate the Fisher information and the Shannon entropy for the simplest
case corresponding the lowest-lying state of each system. While there is no
problem in defining the Shannon entropy for noncommutating spaces, the
definition of the Fisher information had to be modified to satisfy the
Cramer-Rao inequalities. We observe for both systems, how the Fisher
information and Shannon entropy in position and momentum change due to the
noncommutativity of the space. We verified that the Bialynicki-Birula-Mycielski
(BBM) entropic uncertainty relation still holds in the systems considered.


title:
Pressure effects on crystal and electronic structure of bismuth
  tellurohalides

abstract:
  We study the possibility of pressure-induced transitions from a normal
semiconductor to a topological insulator (TI) in bismuth tellurohalides using
density functional theory and tight-binding method. In BiTeI this transition is
realized through the formation of an intermediate phase, a Weyl semimetal, that
leads to modification of surface state dispersions. In the topologically
trivial phase, the surface states exhibit a Bychkov-Rashba type dispersion. The
Weyl semimetal phase exists in a narrow pressure interval of 0.2 GPa. After the
Weyl semimetal--TI transition occurs, the surface electronic structure is
characterized by gapless states with linear dispersion. The peculiarities of
the surface states modification under pressure depend on the band-bending
effect. We have also calculated the frequencies of Raman active modes for BiTeI
in the proposed high-pressure crystal phases in order to compare them with
available experimental data. Unlike BiTeI, in BiTeBr and BiTeCl the topological
phase transition does not occur. In BiTeBr, the crystal structure changes with
pressure but the phase remains a trivial one. However, the transition appears
to be possible if the low-pressure crystal structure is retained. In BiTeCl
under pressure, the topological phase does not appear up to 18 GPa due to a
relatively large band gap width in this compound.


title: Reconstruction of Solar Subsurfaces by Local Helioseismology

abstract:
  Local helioseismology has opened new frontiers in our quest for understanding
of the internal dynamics and dynamo on the Sun. Local helioseismology
reconstructs subsurface structures and flows by extracting coherent signals of
acoustic waves traveling through the interior and carrying information about
subsurface perturbations and flows, from stochastic oscillations observed on
the surface. The initial analysis of the subsurface flow maps reconstructed
from the 5 years of SDO/HMI data by time-distance helioseismology reveals the
great potential for studying and understanding of the dynamics of the quiet Sun
and active regions, and the evolution with the solar cycle. In particular, our
results show that the emergence and evolution of active regions are accompanied
by multi-scale flow patterns, and that the meridional flows display the
North-South asymmetry closely correlating with the magnetic activity. The
latitudinal variations of the meridional circulation speed, which are probably
related to the large-scale converging flows, are mostly confined in shallow
subsurface layers. Therefore, these variations do not necessarily affect the
magnetic flux transport. The North-South asymmetry is also pronounced in the
variations of the differential rotation ("torsional oscillations"). The
calculations of a proxy of the subsurface kinetic helicity density show that
the helicity does not vary during the solar cycle, and that supergranulation is
a likely source of the near-surface helicity.

categories: astro-ph.SR physics.flu-dyn physics.geo-ph physics.plasm-ph


title:
Hidden Magnetism in Periodically Modulated One Dimensional Dipolar
  Fermions

abstract:
  The experimental realization of time dependent ultracold lattice systems has
paved the way towards the implementation of new Hubbard-like Hamiltonians. We
show that in a one dimensional two components lattice dipolar Fermi gas the
competition between long range repulsion and correlated hopping induced by
periodically modulated on-site interaction allows for the formation of exotic
hidden magnetic phases. The magnetism, characterized solely by string-like
nonlocal order parameters, manifests itself both in the charge and, noticeably,
in the spin degrees of freedom. Such behavior is enlighten by employing both
Luttinger theory and numerical methods. Crucially the range of parameters for
which hidden magnetism is present can be reached by means of the currently
available experimental setups and probes.


title: Magnetic Diagnostics of the Solar Chromosphere with the Mg II h-k Lines

abstract:
  We investigated the formation of the Mg II h-k doublet in a weakly magnetized
atmosphere (20-100 G) using a newly developed numerical code for polarized RT
in a plane-parallel geometry, which implements a recent formulation of
partially coherent scattering by polarized multi-term atoms in arbitrary
magnetic field regimes. Our results confirm the importance of partial
redistribution effects in the formation of the Mg II h and k lines, as pointed
out by previous work in the non-magnetic case. We show that the presence of a
magnetic field can produce measurable modifications of the broadband linear
polarization even for relatively small field strengths (~10 G), while the
circular polarization remains well represented by the classical magnetograph
formula. Both these results open an important new window for the weak-field
diagnostics of the upper solar atmosphere.


title: Kondo effect in a quantum wire with spin-orbit coupling

abstract:
  The influence of spin-orbit interactions on the Kondo effect has been under
debate recently. Studies conducted recently on a system composed by an Anderson
impurity on a 2DEG with Rashba spin-orbit have been shown that it can enhance
or suppress the Kondo temperature ($T_{\rm K}$), depending on the relative
energy level position of the impurity with respect to the particle-hole
symmetric point. Here we investigate a system composed by a single Anderson
impurity side-coupled to a quantum wire with spin-orbit coupling (SOC). We
derive an effective Hamiltonian in which the Kondo coupling is modified by the
SOC. In addition, the Hamiltonian contains two other scattering terms, the so
called Dzaloshinskyi-Moriya interaction, know to appear in these systems, and a
new one describing processes similar to the Elliott-Yafet scattering
mechanisms. By performing a renormalization group analysis on the effective
Hamiltonian, we find that the correction on the Kondo coupling due to the SOC
favors and enhancement of the Kondo temperature even in the particle-hole
symmetric point of the Anderson model, agreeing with the NRG results. Moreover,
away from the particle-hole symmetric point, $T_{\rm K}$ always increases with
the SOC, accordingly with the previous renormalization group analysis.


title: Finite Dehn surgeries on knots in $S^3$

abstract:
  We show that on a hyperbolic knot $K$ in $S^3$, the distance between any two
finite surgery slopes is at most two and consequently there are at most three
nontrivial finite surgeries. Moreover in case that $K$ admits three nontrivial
finite surgeries, $K$ must be the pretzel knot $P(-2,3,7)$. In case that $K$
admits two noncyclic finite surgeries or two finite surgeries at distance two,
the two surgery slopes must be one of ten or seventeen specific pairs
respectively. For $D$-type finite surgeries, we improve a finiteness theorem
due to Doig by giving an explicit bound on the possible resulting prism
manifolds, and also prove that $4m$ and $4m+4$ are characterizing slopes for
the torus knot $T(2m+1,2)$ for each $m\geq 1$.


title: Flexocoupling impact on the kinetics of polarization reversal

abstract:
  The impact of flexoelectric coupling on polarization reversal kinetics and
space charge dynamics in thin films of ferroelectric-semiconductors has been
theoretically studied. The relaxation-type Landau-Khalatnikov equation together
with the Poisson equation and the theory of elasticity equations have been used
to calculate in a self-consistent way the spatial-temporal development of
ferroelectric polarization, electric potential and space charge, elastic
stresses, strains and their gradients. The analysis of the obtained results
reveals a moderate increase of the flexocoupling influence on the polarization,
elastic strain, electric potential and space charge distribution dynamics with
the decrease of a ferroelectric film thickness. In contrast, the dependence of
polarization switching time on the applied electric field is strongly affected
by the flexocoupling strength. The polarization reversal process consists
typically of two stages, the first stage has no characteristic time, while the
second one exhibits a switching time strongly dependent on the applied electric
field.


title:
Minimizing irreversible losses in quantum systems by local
  counter-diabatic driving

abstract:
  Counter-diabatic driving protocols were proposed as a means to do fast
changes in the Hamiltonian without exciting transitions. Such driving in
principle allows one to realize arbitrarily fast annealing protocols or
implement fast dissipationless driving, circumventing standard adiabatic
limitations requiring infinitesimally slow rates. These ideas were tested and
used both experimentally and theoretically in small systems, but in larger
chaotic systems it is known that exact counter-diabatic protocols do not exist.
In this work we develop a simple variational approach allowing one to find best
possible counter-diabatic protocols given physical constraints like locality.
These protocols are easy to derive and implement both experimentally and
numerically. We show that, using these approximate protocols, one can
drastically decrease dissipation and increase fidelity of quantum annealing
protocols in complex many-particle systems. In the fast limit these protocols
provide an effective dual description of adiabatic dynamics where the coupling
constant plays the role of time and the counter-diabatic term plays the role of
the Hamiltonian.


title:
Towards 'smart lasers': self-optimisation of an ultrafast pulse source
  using a genetic algorithm

abstract:
  Short-pulse fibre lasers are a complex dynamical system possessing a broad
space of operating states that can be accessed through control of cavity
parameters. Determination of target regimes is a multi-parameter global
optimisation problem. Here, we report the implementation of a genetic algorithm
to intelligently locate optimum parameters for stable single-pulse mode-locking
in a Figure-8 fibre laser, and fully automate the system turn-on procedure.
Stable ultrashort pulses are repeatably achieved by employing a compound
fitness function that monitors both temporal and spectral output properties of
the laser. Our method of encoding photonics expertise into an algorithm and
applying machine-learning principles paves the way to self-optimising `smart'
optical technologies.


title:
Synthesis of strontium ferrite/iron oxide exchange coupled nano-powders
  with improved energy product for rare earth free permanent magnet
  applications

abstract:
  We present a simple, scalable synthesis route for producing exchange coupled
soft/hard magnetic composite powder that outperforms pure soft and hard phase
constituents. Importantly, the composites is iron oxide based (SrFe12O19 and
Fe3O4) and contain no rare earth or precious metal. The two step synthesis
process consists of first precipitating, an Iron oxide/hydroxide precursor
directly on top of SrFe12O19 nano-flakes, ensuring a very fine degree of mixing
between the hard and the soft magnetic phases. We then use a second step that
serves to reduce the precursor to create the proper soft magnetic phase and
create the intimate interface necessary for exchange coupling. We establish a
clear processing window; at temperatures below this window the desired soft
phase is not produced, while higher temperatures result in deleterious reaction
at the soft/hard phase interfaces, causing an improper ratio of soft to hard
phases. Improvements of Mr, Ms, and (BH)max are 42%, 29% and 37% respectively
in the SrFe12O19/Fe3O4 composite compared to pure hard phase (SrFe12O19). We
provide evidence of coupling (exchange spring behavior) with hysteresis curves,
first order reversal curve (FORC) analysis and recoil measurements.


title: Stochastic Backpropagation through Mixture Density Distributions

abstract:
  The ability to backpropagate stochastic gradients through continuous latent
distributions has been crucial to the emergence of variational autoencoders and
stochastic gradient variational Bayes. The key ingredient is an unbiased and
low-variance way of estimating gradients with respect to distribution
parameters from gradients evaluated at distribution samples. The
"reparameterization trick" provides a class of transforms yielding such
estimators for many continuous distributions, including the Gaussian and other
members of the location-scale family. However the trick does not readily extend
to mixture density models, due to the difficulty of reparameterizing the
discrete distribution over mixture weights. This report describes an
alternative transform, applicable to any continuous multivariate distribution
with a differentiable density function from which samples can be drawn, and
uses it to derive an unbiased estimator for mixture density weight derivatives.
Combined with the reparameterization trick applied to the individual mixture
components, this estimator makes it straightforward to train variational
autoencoders with mixture-distributed latent variables, or to perform
stochastic variational inference with a mixture density variational posterior.


title:
Information-theoretical label embeddings for large-scale image
  classification

abstract:
  We present a method for training multi-label, massively multi-class image
classification models, that is faster and more accurate than supervision via a
sigmoid cross-entropy loss (logistic regression). Our method consists in
embedding high-dimensional sparse labels onto a lower-dimensional dense sphere
of unit-normed vectors, and treating the classification problem as a cosine
proximity regression problem on this sphere. We test our method on a dataset of
300 million high-resolution images with 17,000 labels, where it yields
considerably faster convergence, as well as a 7% higher mean average precision
compared to logistic regression.


title: The Interplay between Frustration and Entanglement in Many-Body Systems

abstract:
  Frustration of classical many-body systems can be used to distinguish
ferromagnetic interactions from anti-ferromagnetic ones via the Toulouse
conditions. A quantum version of the Toulouse conditions provides a similar
classification based on the local ground states. We compute the global ground
states for a family of models with Heisenberg-like interactions and analyse
their behaviour with respect to frustration, entanglement and degeneracy. For
that we develop analytical and numerical analysing tools capable to quantify
the interplay between those three quantities. We find that the quantum Toulouse
conditions provide a proper classification, however, refinements can be found.
Our results show how the different local ground states affect the interplay and
pave the way for further generalisation and possible applications to other
quantum many-body systems.


title:
Fermi-surface transformation across the pseudogap critical point of the
  cuprate superconductor La$_{1.6-x}$Nd$_{0.4}$Sr$_{x}$CuO$_4$

abstract:
  The electrical resistivity $\rho$ and Hall coefficient R$_H$ of the
tetragonal single-layer cuprate Nd-LSCO were measured in magnetic fields up to
$H = 37.5$ T, large enough to access the normal state at $T \to 0$, for closely
spaced dopings $p$ across the pseudogap critical point at $p^\star = 0.235$.
Below $p^\star$, both coefficients exhibit an upturn at low temperature, which
gets more pronounced with decreasing $p$. Taken together, these upturns show
that the normal-state carrier density $n$ at $T = 0$ drops upon entering the
pseudogap phase. Quantitatively, it goes from $n = 1 + p$ at $p = 0.24$ to $n =
p$ at $p = 0.20$. By contrast, the mobility does not change appreciably, as
revealed by the magneto-resistance. The transition has a width in doping and
some internal structure, whereby R$_H$ responds more slowly than $\rho$ to the
opening of the pseudogap. We attribute this difference to a Fermi surface that
supports both hole-like and electron-like carriers in the interval $0.2 < p <
p^\star$, with compensating contributions to R$_H$. Our data are in excellent
agreement with recent high-field data on YBCO and LSCO. The quantitative
consistency across three different cuprates shows that a drop in carrier
density from $1 + p$ to $p$ is a universal signature of the pseudogap
transition at $T=0$. We discuss the implication of these findings for the
nature of the pseudogap phase.


title:
Un contre-exemple \`a la dichotomie r\'ecurrence/transience sur les
  espaces homog\`enes

abstract:
  Take $G$ a locally compact second-countable group, and $H$ a subgroup of $G$.
Choose $\mu$ a probability measure on $G$, such that the group spanned by its
support is dense in $G$, and consider the Markov chain on the homogeneous space
$X=G/H$ with transition probability $P_x=\mu *\delta_x$ for $x\in X$. Under
some conditions on $G$, $H$, $\mu$, we know that this Markov chain is either
everywhere recurrent or everywhere transient. A natural question is whether
such a dichotomy is universally true. The goal of this paper is to show it is
not, even when $G$ is finitely generated, through the explicit construction of
a counter example. The methods used include the study of stable laws,
Gnedenko-Kolmogorov's local limit theorem for stable laws, and the study of the
time of first return to equilibrium.


title: FusionNet: 3D Object Classification Using Multiple Data Representations

abstract:
  High-quality 3D object recognition is an important component of many vision
and robotics systems. We tackle the object recognition problem using two data
representations, to achieve leading results on the Princeton ModelNet
challenge. The two representations: 1. Volumetric representation: the 3D object
is discretized spatially as binary voxels - $1$ if the voxel is occupied and
$0$ otherwise. 2. Pixel representation: the 3D object is represented as a set
of projected 2D pixel images. Current leading submissions to the ModelNet
Challenge use Convolutional Neural Networks (CNNs) on pixel representations.
However, we diverge from this trend and additionally, use Volumetric CNNs to
bridge the gap between the efficiency of the above two representations. We
combine both representations and exploit them to learn new features, which
yield a significantly better classifier than using either of the
representations in isolation. To do this, we introduce new Volumetric CNN
(V-CNN) architectures.


title:
The late time structure of high density contrast, single mode
  Richtmyer-Meshkov flow

abstract:
  We study the late time flow structure of Richtmyer-Meshkov instability.
Recent numerical work has suggested a self-similar collapse of the development
of this instability at late times, independent of the initial surface profile.
Using the form of collapse suggested, we derive an analytic expression for the
mass-velocity relation in the spikes, and a global theory for the late time
flow structure. We compare these results with fluid dynamical simulation.


title: How to Discreetly Spread a Rumor in a Crowd

abstract:
  In this paper, we study PUSH-PULL style rumor spreading algorithms in the
mobile telephone model, a variant of the classical telephone model in which
each node can participate in at most one connection per round; i.e., you can no
longer have multiple nodes pull information from the same source in a single
round. Our model also includes two new parameterized generalizations: (1) the
network topology can undergo a bounded rate of change (for a parameterized rate
that spans from no changes to changes in every round); and (2) in each round,
each node can advertise a bounded amount of information to all of its neighbors
before connection decisions are made (for a parameterized number of bits that
spans from no advertisement to large advertisements). We prove that in the
mobile telephone model with no advertisements and no topology changes,
PUSH-PULL style algorithms perform poorly with respect to a graph's vertex
expansion and graph conductance as compared to the known tight results in the
classical telephone model. We then prove, however, that if nodes are allowed to
advertise a single bit in each round, a natural variation of PUSH-PULL
terminates in time that matches (within logarithmic factors) this strategy's
performance in the classical telephone model---even in the presence of frequent
topology changes. We also analyze how the performance of this algorithm
degrades as the rate of change increases toward the maximum possible amount. We
argue that our model matches well the properties of emerging peer-to-peer
communication standards for mobile devices, and that our efficient PUSH-PULL
variation that leverages small advertisements and adapts well to topology
changes is a good choice for rumor spreading in this increasingly important
setting.


title: Un crit\`ere de r\'ecurrence pour certains espaces homog\`enes

abstract:
  Let $G$ be a real connected algebraic semi-simple Lie group, and $H$ an
algebraic subgroup of $G$. Let $\mu$ be a probability measure on $G$, with
finite exponential moment, whose support spans a Zariski-dense subsemigroup of
$G$. Let $X=G/H$ be the quotient of $G$ by $H$. We study the Markov chain on
$X$ with transition probability $P_x=\mu *\delta_x$ for $x\in X$. We prove that
either for every $x\in X$, almost every trajectory starting from $x$ is
transient or for every $x\in X$, almost every trajectory starting from $x$ is
recurrent. In fact, this recurrence is uniform over all $X$, i.e. there exists
a compact set $C\subset X$ such that for each point $x\in X$, every trajectory
starting in $x$ almost surely returns to $C$ infinitely often. Furthermore, we
give a criterion for recurrence depending on $G$, $H$, and $\mu$.


title: Stochastic Epidemic Networks with Strategic Link Formation

abstract:
  Understanding cascading failures or epidemics in networks is crucial for
developing effective defensive mechanisms for many critical systems and
infrastructures (e.g. biological, social and cyber networks). Most of the
existing works treat the network topology as being exogenously given and study
under what conditions an epidemic breaks out and/or extinguishes. However, if
agents are able to strategically decide their connections according to their
own self-interest, the network will instead be endogenously formed and
evolving. In such systems, the epidemic, agents' strategic decisions and the
network structure become complexly coupled and co-evolve. As a result, existing
knowledge may no longer be applicable. Built on a continuous time
Susceptible-Infected-Susceptible epidemic model with strong mixing, this paper
studies stochastic epidemic networks consisting of strategic agents, who decide
the number of links to form based on a careful evaluation of its current
obtainable benefit and the potential future cost due to infection by forming
links. A game theoretical framework is developed to analyze such networks and a
number of important insights are obtained. One key result is that whereas an
epidemic eventually dies out if the effective spreading rate is sufficiently
low in exogenously given networks, it never dies out when agents are strategic
regardless of the effective spreading rate. This property leads to reduced
achievable system efficiency and considerably different optimal protection
mechanisms. Without understanding the strategic behavior of agents, significant
security cost may incur.


title:
Custom Chipset and Compact Module Design for a 75-110 GHz Laboratory
  Signal Source

abstract:
  We report on the development and characterization of a compact,
full-waveguide bandwidth (WR-10) signal source for general-purpose testing of
mm-wave components. The MMIC-based multichip module is designed for compactness
and ease-of-use, especially in size-constrained test sets such as a wafer probe
station. It takes as input a cm-wave CW reference and provides a factor of
three frequency multiplication as well as amplification, output power
adjustment, and in-situ output power monitoring. It utilizes a number of custom
MMIC chips such as a Schottky-diode limiter and a broadband mm-wave detector,
both designed explicitly for this module, as well as custom millimeter-wave
multipliers and amplifiers reported in previous papers.


title: Einstein-Yang-Mills from pure Yang-Mills amplitudes

abstract:
  We present new relations for scattering amplitudes of color ordered gluons
and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary
multiplicities and polarizations involving up to three gravitons and up to two
color traces are reduced to partial amplitudes of pure Yang-Mills theory. In
fact, the double-trace identities apply to Einstein-Yang-Mills extended by a
dilaton and a B-field. Our results generalize recent work of Stieberger and
Taylor for the single graviton case with a single color trace. As the
derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our
results are valid for external bosons in any number of spacetime dimensions.
Moreover, they generalize to the superamplitudes in theories with 16
supercharges.


title: Integration of Probabilistic Uncertain Information

abstract:
  We study the problem of data integration from sources that contain
probabilistic uncertain information. Data is modeled by possible-worlds with
probability distribution, compactly represented in the probabilistic relation
model. Integration is achieved efficiently using the extended probabilistic
relation model. We study the problem of determining the probability
distribution of the integration result. It has been shown that, in general,
only probability ranges can be determined for the result of integration. In
this paper we concentrate on a subclass of extended probabilistic relations,
those that are obtainable through integration. We show that under intuitive and
reasonable assumptions we can determine the exact probability distribution of
the result of integration.


title: Extended Symmetries at the Black Hole Horizon

abstract:
  We prove that non-extremal black holes in four-dimensional general relativity
exhibit an infinite-dimensional symmetry in their near horizon region. By
prescribing a physically sensible set of boundary conditions at the horizon, we
derive the algebra of asymptotic Killing vectors, which is shown to be
infinite-dimensional and includes, in particular, two sets of supertranslations
and two mutually commuting copies of the Virasoro algebra. We define the
surface charges associated to the asymptotic diffeomorphisms that preserve the
boundary conditions and discuss the subtleties of this definition, such as the
integrability conditions and the correct definition of the Dirac brackets. When
evaluated on the stationary solutions, the only non-vanishing charges are the
zero-modes. One of them reproduces the Bekenstein-Hawking entropy of Kerr black
holes. We also study the extremal limit, recovering the NHEK geometry. In this
singular case, where the algebra of charges and the integrability conditions
get modified, we find that the computation of the zero-modes correctly
reproduces the black hole entropy. Furthermore, we analyze the case of three
spacetime dimensions, in which the integrability conditions notably simplify
and the field equations can be solved analytically to produce a family of exact
solutions that realize the boundary conditions explicitly. We examine other
features, such as the form of the algebra in the extremal limit and the
relation to other works in the literature.


title: FPGA based hybrid architecture for parallelizing RRT

abstract:
  Field Programmable Gate Arrays(FPGA) exceed the computing power of software
based implementations by breaking the paradigm of sequential execution and
accomplishing more per clock cycle by enabling hardware level parallelization
at an architectural level. Introducing parallel architectures for a
computationally intensive algorithm like Rapidly Exploring Random Trees(RRT)
will result in an exploration that is fast, dense and uniform. Through a cost
function delineated in later sections, FPGA based combinatorial architecture
delivers superlative speed-up but consumes very high power while hierarchical
architecture delivers relatively lower speed-up with acceptable power
consumption levels. To combine the qualities of both, a hybrid architecture,
that encompasses both combinatorial and hierarchical architecture, is designed.
To determine the number of RRT nodes to be allotted to the combinatorial and
hierarchical blocks of the hybrid architecture, a cost function, comprised of
fundamentally inversely related speed-up and power parameters, is formulated.
This maximization of cost function, with its associated constraints,is then
mathematically solved using a modified branch and bound, that leads to optimal
allocation of RRT modules to both blocks. It is observed that this hybrid
architecture delivers the highest performance-per-watt out of the three
architectures for differential, quad-copter and fixed wing kinematics.


title: Splitting Mass Spectra and Muon g-2 in Higgs-Anomaly Mediation

abstract:
  We propose a scenario where only the Higgs multiplets have direct couplings
to a supersymmetry (SUSY) breaking sector. The standard model matter multiplets
as well as the gauge multiples are sequestered from the SUSY breaking sector;
therefore, their masses arise via anomaly mediation at the high energy scale
with a gravitino mass of $\sim$100 TeV. Due to renormalization group running
effects from the Higgs soft masses, the masses of the third generation
sfermions become O(10) TeV at the low energy scale, while the first and second
generation sfermion masses are O(0.1-1) TeV, avoiding the tachyonic slepton
problem and flavor changing neutral current problem. With the splitting mass
spectrum, the muon g-2 anomaly is explained consistently with the observed
Higgs boson mass of 125 GeV. Moreover, the third generation Yukawa couplings
are expected to be unified in some regions.


title:
Born-Infeld condensate as a possible origin of neutrino masses and dark
  energy

abstract:
  We discuss the possibility that a Born-Infeld condensate coupled to neutrinos
can generate both neutrino masses and an effective cosmological constant. In
particular, an effective field theory is provided capable of dynamically
realizing the neutrino superfluid phase firstly suggested by Ginzburg and
Zharkov. In such a case, neutrinos acquire a mass gap inside the Born-Infeld
ether forming a long-range Cooper pair. Phenomenological implications of the
approach are also discussed.


title: Lowering IrGL to CUDA

abstract:
  The IrGL intermediate representation is an explicitly parallel representation
for irregular programs that targets GPUs. In this report, we describe IrGL
constructs, examples of their use and how IrGL is compiled to CUDA by the
Galois GPU compiler.


title:
Detectors and cooling technology for direct spectroscopic biosignature
  characterization

abstract:
  Direct spectroscopic biosignature characterization (hereafter "biosignature
characterization") will be a major focus for future space observatories
equipped with coronagraphs or starshades. Our aim in this article is to provide
an introduction to potential detector and cooling technologies for biosignature
characterization. We begin by reviewing the needs. These include nearly
noiseless photon detection at flux levels as low as
$<0.001~\textrm{photons}~s^{-1}~\textrm{pixel}^{-1}$ in the visible and
near-IR. We then discuss potential areas for further testing and/or development
to meet these needs using non-cryogenic detectors (EMCCD, HgCdTe array, HgCdTe
APD array), and cryogenic single photon detectors (MKID arrays and TES
microcalorimeter arrays). Non-cryogenic detectors are compatible with the
passive cooling that is strongly preferred by coronagraphic missions, but would
add non-negligible noise. Cryogenic detectors would require active cooling, but
in return deliver nearly quantum limited performance. Based on the flight
dynamics of past NASA missions, we discuss reasonable vibration expectations
for a large UV-Optical-IR space telescope (LUVOIR) and preliminary cooling
concepts that could potentially fit into a vibration budget without being the
largest element. We believe that a cooler that meets the stringent vibration
needs of a LUVOIR is also likely to meet those of a starshade-based Habitable
Exoplanet Imaging Mission.


title: Multi-category Angle-based Classifier Refit

abstract:
  Classification is an important statistical learning tool. In real
application, besides high prediction accuracy, it is often desirable to
estimate class conditional probabilities for new observations. For traditional
problems where the number of observations is large, there exist many well
developed approaches. Recently, high dimensional low sample size problems are
becoming increasingly popular. Margin-based classifiers, such as logistic
regression, are well established methods in the literature. On the other hand,
in terms of probability estimation, it is known that for binary classifiers,
the commonly used methods tend to under-estimate the norm of the classification
function. This can lead to biased probability estimation. Remedy approaches
have been proposed in the literature. However, for the simultaneous
multicategory classification framework, much less work has been done. We fill
the gap in this paper. In particular, we give theoretical insights on why heavy
regularization terms are often needed in high dimensional applications, and how
this can lead to bias in probability estimation. To overcome this difficulty,
we propose a new refit strategy for multicategory angle-based classifiers. Our
new method only adds a small computation cost to the problem, and is able to
attain prediction accuracy that is as good as the regular margin-based
classifiers. On the other hand, the improvement of probability estimation can
be very significant. Numerical results suggest that the new refit approach is
highly competitive.


title: Emergent Hyperbolic Network Geometry

abstract:
  A large variety of interacting complex systems are characterized by
interactions occurring between more than two nodes. These systems are described
by simplicial complexes. Simplicial complexes are formed by simplices (nodes,
links, triangles, tetrahedra etc.) that have a natural geometric
interpretation. As such simplicial complexes are widely used in quantum gravity
approaches that involve a discretization of spacetime. Here, by extending our
knowledge of growing complex networks to growing simplicial complexes we
investigate the nature of the emergent geometry of complex networks and explore
whether this geometry is hyperbolic. Specifically we show that an hyperbolic
network geometry emerges spontaneously from models of growing simplicial
complexes that are purely combinatorial. The statistical and geometrical
properties of the growing simplicial complexes strongly depend on their
dimensionality and display the major universal properties of real complex
networks (scale-free degree distribution, small-world and communities) at the
same time. Interestingly, when the network dynamics includes an heterogeneous
fitness of the faces, the growing simplicial complex can undergo phase
transitions that are reflected by relevant changes in the network geometry.


title: Degenerate Density Perturbation Theory

abstract:
  Fractional occupation numbers can be used in density functional theory to
create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate
eigenvalues. We develop the corresponding perturbation theory and apply it to a
system of $N_d$ degenerate electrons in a harmonic oscillator potential. The
order-by-order expansions of both the fractional occupation numbers and unitary
transformations within the degenerate subspace are determined by the
requirement that a differentiable map exists connecting the initial and
perturbed states. Using the X$\alpha$ exchange-correlation (XC) functional, we
find an analytic solution for the first-order density and first through
third-order energies as a function of $\alpha$, with and without a
self-interaction correction. The fact that the XC Hessian is not positive
definite plays an important role in the behavior of the occupation numbers.


title: Structure-Blind Signal Recovery

abstract:
  We consider the problem of recovering a signal observed in Gaussian noise. If
the set of signals is convex and compact, and can be specified beforehand, one
can use classical linear estimators that achieve a risk within a constant
factor of the minimax risk. However, when the set is unspecified, designing an
estimator that is blind to the hidden structure of the signal remains a
challenging problem. We propose a new family of estimators to recover signals
observed in Gaussian noise. Instead of specifying the set where the signal
lives, we assume the existence of a well-performing linear estimator. Proposed
estimators enjoy exact oracle inequalities and can be efficiently computed
through convex optimization. We present several numerical illustrations that
show the potential of the approach.


title:
Disk Detective: Discovery of New Circumstellar Disk Candidates through
  Citizen Science

abstract:
  The Disk Detective citizen science project aims to find new stars with 22
micron excess emission from circumstellar dust using data from NASA's WISE
mission. Initial cuts on the AllWISE catalog provide an input catalog of
277,686 sources. Volunteers then view images of each source online in 10
different bands to identify false-positives (galaxies, background stars,
interstellar matter, image artifacts, etc.). Sources that survive this online
vetting are followed up with spectroscopy on the FLWO Tillinghast telescope.
This approach should allow us to unleash the full potential of WISE for finding
new debris disks and protoplanetary disks. We announce a first list of 37 new
disk candidates discovered by the project, and we describe our vetting and
follow-up process. One of these systems appears to contain the first debris
disk discovered around a star with a white dwarf companion: HD 74389. We also
report four newly discovered classical Be stars (HD 6612, HD 7406, HD 164137,
and HD 218546) and a new detection of 22 micron excess around a previously
known debris disk host star, HD 22128.


title: On the tightness of correlation inequalities with no quantum violation

abstract:
  We study the faces of the set of quantum correlations, i.e., the Bell and
noncontextuality inequalities without any quantum violation. First, we
investigate the question whether every proper (tight) Bell inequality for two
parties, other than the trivial ones from positivity, normalization and
no-signaling can be violated by quantum correlations, i.e., whether the
classical Bell polytope or the smaller correlation polytope share any facets
with their respective quantum sets. To do this, we develop a recently derived
bound on the quantum value of linear games based on the norms of game matrices
to give a simple sufficient condition to identify linear games with no quantum
advantage. Additionally we show how this bound can be extended to the general
class of unique games, illustrating it for the case of three outcomes. We then
show as a main result that the paradigmatic examples of correlation Bell
inequalities with no quantum violation, namely the non-local computation games
do not constitute tight Bell inequalities, not even for the correlation
polytope. We also extend this to an arbitrary prime number of outcomes for a
specific class of these games. We then study the faces in the simplest CHSH
Bell scenario of binary dichotomic measurements, and identify edges in the set
of quantum correlations in this scenario.
  Finally, we relate the non-contextual polytope of single-party correlation
inequalities with the cut polytope $CUT(\nabla G)$, where $G$ denotes the
compatibility graph of observables in the contextuality scenario and $\nabla G$
denotes the suspension graph of $G$. We observe that there exist tight
non-contextuality inequalities with no quantum violation, and furthermore that
this set of inequalities is beyond those implied by the Consistent Exclusivity
principle.


title: On dynamical systems approaches and methods in $f(R)$ cosmology

abstract:
  We discuss dynamical systems approaches and methods applied to flat
Robertson-Walker models in $f(R)$-gravity. We argue that a complete description
of the solution space of a model requires a global state space analysis that
motivates globally covering state space adapted variables. This is shown
explicitly by an illustrative example, $f(R) = R + \alpha R^2$, $\alpha > 0$,
for which we introduce new regular dynamical systems on global compactly
extended state spaces for the Jordan and Einstein frames. This example also
allows us to illustrate several local and global dynamical systems techniques
involving, e.g., blow ups of nilpotent fixed points, center manifold analysis,
averaging, and use of monotone functions. As a result of applying dynamical
systems methods to globally state space adapted dynamical systems formulations,
we obtain pictures of the entire solution spaces in both the Jordan and the
Einstein frames. This shows, e.g., that due to the domain of the conformal
transformation between the Jordan and Einstein frames, not all the solutions in
the Jordan frame are completely contained in the Einstein frame. We also make
comparisons with previous dynamical systems approaches to $f(R)$ cosmology and
discuss their advantages and disadvantages.

categories: gr-qc astro-ph.CO math-ph math.DS math.MP


title: Sums of twisted circulants

abstract:
  The rate of convergence of simple random walk on the Heisenberg group over
$Z/nZ$ with a standard generating set was determined by Bump et al [1,2]. We
extend this result to random walks on the same groups with an arbitrary minimal
symmetric generating set. We also determine the rate of convergence of simple
random walk on higher-dimensional versions of the Heisenberg group with a
standard generating set. We obtain our results via Fourier analysis, using an
eigenvalue bound for sums of twisted circulant matrices. The key tool is a
generalization of a version of the Heisenberg Uncertainty Principle due to
Donoho-Stark [4].


title: The far infra-red SEDs of main sequence and starburst galaxies

abstract:
  We compare observed far infra-red/sub-millimetre (FIR/sub-mm) galaxy spectral
energy distributions (SEDs) of massive galaxies ($M_{\star}\gtrsim10^{10}$
$h^{-1}$M$_{\odot}$) derived through a stacking analysis with predictions from
a new model of galaxy formation. The FIR SEDs of the model galaxies are
calculated using a self-consistent model for the absorption and re-emission of
radiation by interstellar dust based on radiative transfer calculations and
global energy balance arguments. Galaxies are selected based on their position
on the specific star formation rate (sSFR) - stellar mass ($M_{\star}$) plane.
We identify a main sequence of star-forming galaxies in the model, i.e. a well
defined relationship between sSFR and $M_\star$, up to redshift $z\sim6$. The
scatter of this relationship evolves such that it is generally larger at higher
stellar masses and higher redshifts. There is remarkable agreement between the
predicted and observed average SEDs across a broad range of redshifts
($0.5\lesssim z\lesssim4$) for galaxies on the main sequence. However, the
agreement is less good for starburst galaxies at $z\gtrsim2$, selected here to
have elevated sSFRs$>10\times$ the main sequence value. We find that the
predicted average SEDs are robust to changing the parameters of our dust model
within physically plausible values. We also show that the dust temperature
evolution of main sequence galaxies in the model is driven by star formation on
the main sequence being more burst-dominated at higher redshifts.


title: On two questions about restricted sumsets in finite abelian groups

abstract:
  Let $G$ be an abelian group of finite order $n$, and let $h$ be a positive
integer. A subset $A$ of $G$ is called {\em weakly $h$-incomplete}, if not
every element of $G$ can be written as the sum of $h$ distinct elements of $A$;
in particular, if $A$ does not contain $h$ distinct elements that add to zero,
then $A$ is called {\em weakly $h$-zero-sum-free}. We investigate the maximum
size of weakly $h$-incomplete and weakly $h$-zero-sum-free sets in $G$, denoted
by $C_h(G)$ and $Z_h(G)$, respectively. Among our results are the following:
(i) If $G$ is of odd order and $(n-1)/2 \leq h \leq n-2$, then
$C_h(G)=Z_h(G)=h+1$, unless $G$ is an elementary abelian 3-group and $h=n-3$;
(ii) If $G$ is an elementary abelian 2-group and $n/2 \leq h \leq n-2$, then
$C_h(G)=Z_h(G)=h+2$, unless $h=n-4$.


title:
Entanglement Enabled Intensity Interferometry of Different Wavelengths
  of Light

abstract:
  We propose methods to perform intensity interferometry of photons having two
different wavelengths. Distinguishable particles typically cannot interfere
with each other, but we overcome that obstacle by processing the particles via
entanglement and projection so that they lead to the same final state at the
detection apparatus. Specifically, we discuss how quasi-phase-matched nonlinear
crystals can be used to convert a quantum superposition of light of different
wavelengths onto a common wavelength, while preserving the phase information
essential for their meaningful interference. We thereby gain access to a host
of new observables, which can probe subtle frequency correlations and
entanglement. Further, we generalize the van Cittert-Zernike formula for the
intensity interferometry of extended sources, demonstrate how our proposal
supports enhanced resolution of sources with different spectral character, and
suggest potential applications.


title:
Heat transfer in MHD flow due to a linearly stretching sheet with
  induced magnetic field

abstract:
  The full MHD problem of the flow and heat transfer due to a linearly
stretching sheet in the presence of a transverse magnetic field is put in a
self-similar form. Traditionally ignored physical processes such as induced
magnetic field, viscous dissipation, Joule heating, and work shear are included
and their importance is established. Cases of prescribed surface temperature,
prescribed heat flux, surface feed (injection or suction), velocity slip, and
thermal slip are also considered. The problem is shown to admit self
similarity. Sample numerical solutions are obtained for chosen combinations of
the flow parameters.


title:
A Hybrid Riemann Solver for Large Hyperbolic Systems of Conservation
  Laws

abstract:
  We are interested in the numerical solution of large systems of hyperbolic
conservation laws or systems in which the characteristic decomposition is
expensive to compute. Solving such equations using finite volumes or
Discontinuous Galerkin requires a numerical flux function which solves local
Riemann problems at cell interfaces. There are various methods to express the
numerical flux function. On the one end, there is the robust but very diffusive
Lax-Friedrichs solver; on the other end the upwind Godunov solver which
respects all resulting waves. The drawback of the latter method is the costly
computation of the eigensystem.
  This work presents a family of simple first order Riemann solvers, named
HLLX$\omega$, which avoid solving the eigensystem. The new method reproduces
all waves of the system with less dissipation than other solvers with similar
input and effort, such as HLL and FORCE. The family of Riemann solvers can be
seen as an extension or generalization of the methods introduced by Degond et
al. \cite{DegondPeyrardRussoVilledieu1999}. We only require the same number of
input values as HLL, namely the globally fastest wave speeds in both
directions, or an estimate of the speeds. Thus, the new family of Riemann
solvers is particularly efficient for large systems of conservation laws when
the spectral decomposition is expensive to compute or no explicit expression
for the eigensystem is available.


title:
MHD flow and heat transfer due to the axisymmetric stretching of a sheet
  with induced magnetic field

abstract:
  The full MHD equations, governing the flow due to the axisymmetric stretching
of a sheet in the presence of a transverse magnetic field, can be cast in a
self similar form. This allows evaluation of the induced magnetic field and its
effect on the flow and heat transfer. The problem involves three parameters-
the magnetic Prandtl number, the magnetic interaction number, and the Prandtl
number. Numerical solutions are obtained for the velocity field, the magnetic
field, and the temperature, at different values of the magnetic Prandtl number
and the magnetic interaction number. The contributions of the viscous
dissipation, Joule heating, and streamwise diffusion to the heat flux toward
the sheet are assessed.


title:
Discriminating between L\"uders and von Neumann measuring devices: An
  NMR investigation

abstract:
  Measurement of an observable on a quantum system involves a probabilistic
collapse of the quantum state and a corresponding measurement outcome. L\"uders
and von Neumann state update rules attempt to describe the above
phenomenological observations. These rules are identical for a nondegenerate
observable, but differ for a degenerate observable. While L\"uders rule
preserves superpositions within a degenerate subspace under a measurement of
the corresponding degenerate observable, the von Neumann rule does not.
Recently Hegerfeldt and Mayato [Phys. Rev. A, 85, 032116 (2012)] had formulated
a protocol to discriminate between the two types of measuring devices. Here we
have reformulated this protocol for quantum registers comprising of system and
ancilla qubits. We then experimentally investigated this protocol using nulear
spin systems with the help of NMR techniques, and found that L\"uders rule is
favoured.


title: De-noising the galaxies in the Hubble XDF with EMPCA

abstract:
  We present a method to model optical images of galaxies using Expectation
Maximization Principal Components Analysis (EMPCA). The method relies on the
data alone and does not assume any pre-established model or fitting formula. It
preserves the statistical properties of the sample, minimizing possible biases.
  The precision of the reconstructions appears to be suited for photometric,
morphological and weak lensing analysis, as well as the realization of mock
astronomical images. Here, we put some emphasis on the latter because weak
gravitational lensing is entering a new phase in which systematics are becoming
the major source of uncertainty. Accurate simulations are necessary to perform
a reliable calibration of the ellipticity measurements on which the final bias
depends.
  As a test case, we process $7038$ galaxies observed with the ACS/WFC stacked
images of the Hubble eXtreme Deep Field (XDF) and measure the accuracy of the
reconstructions in terms of their moments of brightness, which turn out to be
comparable to what can be achieved with well-established weak-lensing
algorithms.


title:
Non-quasiparticle transport and resistivity saturation: A view from the
  large-N limit

abstract:
  The electron dynamics in metals are usually well described by the
semiclassical approximation for long-lived quasiparticles. However, in some
metals, the scattering rate of the electrons at elevated temperatures becomes
comparable to the Fermi energy; then, this approximation breaks down, and the
full quantum-mechanical nature of the electrons must be considered. In this
work, we study a solvable, large-$N$ electron-phonon model, which at high
temperatures enters the non-quasiparticle regime. In this regime, the model
exhibits "resistivity saturation" to a temperature-independent value of the
order of the quantum of resistivity - the first analytically tractable model to
do so. The saturation is not due to a fundamental limit on the electron
lifetime, but rather to the appearance of a second conductivity channel. This
is suggestive of the phenomenological "parallel resistor formula", known to
describe the resistivity of a variety of saturating metals.


title:
An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit
  Analysis

abstract:
  We present new, more precise measurements of the mass and distance of our
Galaxy's central supermassive black hole, Sgr A*. These results stem from a new
analysis that more than doubles the time baseline for astrometry of faint stars
orbiting Sgr A*, combining two decades of speckle imaging and adaptive optics
data. Specifically, we improve our analysis of the speckle images by using
information about a star's orbit from the deep adaptive optics data (2005 -
2013) to inform the search for the star in the speckle years (1995 - 2005).
When this new analysis technique is combined with the first complete
re-reduction of Keck Galactic Center speckle images using speckle holography,
we are able to track the short-period star S0-38 (K-band magnitude = 17,
orbital period = 19 years) through the speckle years. We use the kinematic
measurements from speckle holography and adaptive optics to estimate the orbits
of S0-38 and S0-2 and thereby improve our constraints of the mass ($M_{bh}$)
and distance ($R_o$) of Sgr A*: $M_{bh} =
4.02\pm0.16\pm0.04\times10^6~M_{\odot}$ and $7.86\pm0.14\pm0.04$ kpc. The
uncertainties in $M_{bh}$ and $R_o$ as determined by the combined orbital fit
of S0-2 and S0-38 are improved by a factor of 2 and 2.5, respectively, compared
to an orbital fit of S0-2 alone and a factor of $\sim$2.5 compared to previous
results from stellar orbits. This analysis also limits the extended dark mass
within 0.01 pc to less than $0.13\times10^{6}~M_{\odot}$ at 99.7% confidence, a
factor of 3 lower compared to prior work.


title:
Fractionalized Fermi liquid with bosonic chargons as a candidate for the
  pseudogap metal

abstract:
  Doping a Mott-insulating $\mathbb{Z}_2$ spin liquid can lead to a
fractionalized Fermi liquid (FL*). Such a phase has several favorable features
that make it a candidate for the pseudogap metal for the underdoped cuprates.
We focus on a particular, simple $\mathbb{Z}_2$-FL* state which can undergo a
confinement transition to a spatially uniform superconductor which is smoothly
connected to the `plain vanilla' BCS superconductor with $d$-wave pairing. Such
a transition occurs by the condensation of bosonic particles carrying $+e$
charge but no spin (`chargons'). We show that modifying the dispersion of the
bosonic chargons can lead to confinement transitions with charge density waves
and pair density waves at the same wave-vector $\mathbf{K}$, co-existing with
$d$-wave superconductivity. We also compute the evolution of the Hall number in
the normal state during the transition from the plain vanilla FL* state to a
Fermi liquid, and argue, following Coleman, Marston, and Schofield [Phys. Rev.
B 72, 245111 (2005)], that it exhibits a discontinuous jump near optimal
doping. We note the distinction between these results and those obtained from
models of the pseudogap with fermionic chargons.


title:
The moduli spaces of $3d$ ${\cal N} \ge 2$ Chern-Simons gauge theories
  and their Hilbert series

abstract:
  We present a formula for the Hilbert series that counts gauge invariant
chiral operators in a large class of 3d ${\cal N} \ge 2$
Yang-Mills-Chern-Simons theories. The formula counts 't Hooft monopole
operators dressed by gauge invariants of a residual gauge theory of massless
fields in the monopole background. We provide a general formula for the case of
abelian theories, where nonperturbative corrections are absent, and consider a
few examples of nonabelian theories where nonperturbative corrections are well
understood. We also analyze in detail nonabelian ABJ(M) theories as well as
worldvolume theories of M2-branes probing Calabi-Yau fourfold and hyperK\"ahler
twofold singularities with ${\cal N} = 2$ and ${\cal N} = 3$ supersymmetry.


title: Diagrammatic Cancellations and the Gauge Dependence of QED

abstract:
  This letter examines diagrammatic cancellations for Quantum Electrodynamics
(QED) in the general linear gauge. These cancellations combine Feynman graphs
of various topologies and provide a method to reconstruct the gauge dependence
of the electron propagator from the result of a particular gauge by means of a
linear Dyson-Schwinger equation. We use this method in combination with
dimensional regularization to demonstrate how the 3-loop ${\epsilon}$-expansion
in the Feynman gauge determines the ${\epsilon}$-expansions for all gauge
parameter dependent terms to 4 loops.


title:
Signatures of time-reversal-invariant topological superconductivity in
  the Josephson effect

abstract:
  For Josephson junctions based on s-wave superconductors, time-reversal
symmetry is known to allow for powerful relations between the normal-state
junction properties, the excitation spectrum, and the Josephson current. Here
we provide analogous relations for Josephson junctions involving
one-dimensional time-reversal-invariant topological superconductors supporting
Majorana-Kramers pairs, considering both topological-topological and
s-wave-topological junctions. Working in the regime where the junction is much
shorter than the superconducting coherence length, we obtain a number of
analytical and numerical results that hold for arbitrary normal-state
conductance and the most general forms of spin-orbit coupling. The signatures
of topological superconductivity we find include the fractional ac Josephson
effect, which arises in topological-topological junctions provided that the
energy relaxation is sufficiently slow. We also show, for both junction types,
that robust signatures of topological superconductivity arise in the dc
Josephson effect in the form of switches in the Josephson current due to
zero-energy crossings of Andreev levels. The junction spin-orbit coupling
enters the Josephson current only in the topological-topological case and in a
manner determined by the switch locations, thereby allowing quantitative
predictions for experiments with the normal-state conductance, the induced
gaps, and the switch locations as inputs.


title:
Dissecting Galaxies: Spatial and Spectral Separation of Emission Excited
  by Star Formation and AGN Activity

abstract:
  The optical spectra of Seyfert galaxies are often dominated by emission lines
excited by both star formation and AGN activity. Standard calibrations (such as
for the star formation rate) are not applicable to such composite (mixed)
spectra. In this paper, we describe how integral field data can be used to
spectrally and spatially separate emission associated with star formation from
emission associated with accretion onto an active galactic nucleus (AGN). We
demonstrate our method using integral field data for two AGN host galaxies (NGC
5728 and NGC 7679) from the Siding Spring Southern Seyfert Spectroscopic
Snapshot Survey (S7). The spectra of NGC 5728 and NGC 7679 form clear sequences
of AGN fraction on standard emission line ratio diagnostic diagrams. We show
that the emission line luminosities of the majority (> 85 per cent) of spectra
along each AGN fraction sequence can be reproduced by linear superpositions of
the emission line luminosities of one AGN dominated spectrum and one star
formation dominated spectrum. We separate the Halpha, Hbeta, [N
II]$\lambda$6583, [S II]$\lambda \lambda$6716, 6731, [O III]$\lambda$5007 and
[O II]$\lambda \lambda$3726, 3729 luminosities of every spaxel into
contributions from star formation and AGN activity. The decomposed emission
line images are used to derive the star formation rates and AGN bolometric
luminosities for NGC 5728 and NGC 7679. Our calculated values are mostly
consistent with independent estimates from data at other wavelengths. The
recovered star forming and AGN components also have distinct spatial
distributions which trace structures seen in high resolution imaging of the
galaxies, providing independent confirmation that our decomposition has been
successful.


title:
Setting firmer constraints on the evolution of the most massive, central
  galaxies from their local abundances and ages

abstract:
  There is still much debate surrounding how the most massive, central galaxies
in the local universe have assembled their stellar mass, especially the
relative roles of in-situ growth versus later accretion via mergers. In this
paper, we set firmer constraints on the evolutionary pathways of the most
massive central galaxies by making use of empirical estimates on their
abundances and stellar ages. The most recent abundance matching and direct
measurements strongly favour that a substantial fraction of massive galaxies
with Mstar>3x10^11 Msun reside at the centre of clusters with mass
Mhalo>3x10^13 Msun. Spectral analysis supports ages >10 Gyrs, corresponding to
a formation redshift z_form >2. We combine these two pieces of
observationally-based evidence with the mass accretion history of their host
dark matter haloes. We find that in these massive haloes, the stellar mass
locked up in the central galaxy is comparable to, if not greater than, the
total baryonic mass at z_form. These findings indicate that either only a
relatively minor fraction of their present-day stellar mass was formed in-situ
at z_form, or that these massive, central galaxies form in the extreme scenario
where almost all of the baryons in the progenitor halo are converted into
stars. Interestingly, the latter scenario would not allow for any substantial
size growth since the galaxy's formation epoch either via mergers or expansion.
We show our results hold irrespective of systematic uncertainties in stellar
mass, abundances, galaxy merger rates, stellar initial mass function, star
formation rate and dark matter accretion histories.


title:
Demonstration of cosmic microwave background delensing using the cosmic
  infrared background

abstract:
  Delensing is an increasingly important technique to reverse the gravitational
lensing of the cosmic microwave background (CMB) and thus reveal primordial
signals the lensing may obscure. We present a first demonstration of delensing
on Planck temperature maps using the cosmic infrared background (CIB).
Reversing the lensing deflections in Planck CMB temperature maps using a linear
combination of the 545 and 857GHz maps as a lensing tracer, we find that the
lensing effects in the temperature power spectrum are reduced in a manner
consistent with theoretical expectations. In particular, the characteristic
sharpening of the acoustic peaks of the temperature power spectrum resulting
from successful delensing is detected at a significance of 16$\rm{\sigma}$,
with an amplitude of $A_{\rm{delens}} = 1.12 \pm 0.07$ relative to the expected
value of unity. This first demonstration on data of CIB delensing, and of
delensing techniques in general, is significant because lensing removal will
soon be essential for achieving high-precision constraints on inflationary
B-mode polarization.


title: Close-in planetesimal formation by pile-up of drifting pebbles

abstract:
  The consistency of planet formation models suffers from the disconnection
between the regime of small and large bodies. This is primarily caused by
so-called growth barriers: the direct growth of larger bodies is halted at
centimetre-sized objects and particular conditions are required for the
formation of larger, gravitationally bound planetesimals. We aim to connect
models of dust evolution and planetesimal formation to identify regions of
protoplanetary discs that are favourable for the formation of kilometre-sized
bodies and the first planetary embryos. We combine semi-analytical models of
viscous protoplanetary disc evolution, dust growth and drift including
backreaction of the dust particles on the gas, and planetesimal formation via
the streaming instability into one numerical code. We investigate how
planetesimal formation is affected by the mass of the protoplanetary disc, its
initial dust content, and the stickiness of dust aggregates. We find that the
dust growth and drift leads to a global redistribution of solids. The pile-up
of pebbles in the inner disc provides local conditions where the streaming
instability is effective. Planetesimals form in an annulus with its inner edge
lying between 0.3 AU and 1 AU and its width ranging from 0.3 AU to 3 AU. The
resulting surface density of planetesimals follows a radial profile that is
much steeper than the initial disc profile. These results support formation of
terrestrial planets in the solar system from a narrow annulus of planetesimals,
which reproduces their peculiar mass ratios.