title:
Transverse-momentum resummation for Higgs boson pair production at the
  LHC with top-quark mass effects

abstract:
  We consider Higgs boson pair production via gluon fusion in hadronic
collisions. We report the calculation of the transverse-momentum ($q_T$)
distribution of the Higgs boson pair with top-quark mass ($M_t$) effects fully
taken into account. At small values of $q_T$ we resum the
logarithmically-enhanced perturbative QCD contributions up to next-to-leading
logarithmic (NLL) accuracy. At intermediate and large values of $q_T$ we
consistently combine resummation with the ${\cal O}(\alpha_S^3)$ fixed-order
results. After integration over $q_T$, we recover the next-to-leading order
(NLO) result for the inclusive cross section with full dependence on $M_t$. We
present illustrative numerical results at LHC energies, together with an
estimate of the corresponding perturbative uncertainties, and we study the
impact of the top-quark mass effects.


title:
A Search for Very High-Energy Gamma Rays from the Missing Link Binary
  Pulsar J1023+0038 with VERITAS

abstract:
  The binary millisecond radio pulsar PSR J1023+0038 exhibits many
characteristics similar to the gamma-ray binary system PSR B1259--63/LS 2883,
making it an ideal candidate for the study of high-energy non-thermal emission.
It has been the subject of multi-wavelength campaigns following the
disappearance of the pulsed radio emission in 2013 June, which revealed the
appearance of an accretion disk around the neutron star. We present the results
of very high-energy gamma-ray observations carried out by VERITAS before and
after this change of state. Searches for steady and pulsed emission of both
data sets yield no significant gamma-ray signal above 100 GeV, and upper limits
are given for both a steady and pulsed gamma-ray flux. These upper limits are
used to constrain the magnetic field strength in the shock region of the PSR
J1023+0038 system. Assuming that very high-energy gamma rays are produced via
an inverse-Compton mechanism in the shock region, we constrain the shock
magnetic field to be greater than $\sim$2 G before the disappearance of the
radio pulsar and greater than $\sim$10 G afterwards.


title: Making a Case for Learning Motion Representations with Phase

abstract:
  This work advocates Eulerian motion representation learning over the current
standard Lagrangian optical flow model. Eulerian motion is well captured by
using phase, as obtained by decomposing the image through a complex-steerable
pyramid. We discuss the gain of Eulerian motion in a set of practical use
cases: (i) action recognition, (ii) motion prediction in static images, (iii)
motion transfer in static images and, (iv) motion transfer in video. For each
task we motivate the phase-based direction and provide a possible approach.


title: Axion star collisions with Neutron stars and Fast Radio Bursts

abstract:
  Axions may make a significant contribution to the dark matter of the
universe. It has been suggested that these dark matter axions may condense into
localized clumps, called "axion stars." In this paper we argue that collisions
of dilute axion stars with neutron stars, of the type known as "magnetars," may
be the origin of most of the observed fast radio bursts. This idea is a
variation of an idea originally proposed by Iwazaki. However, instead of the
surface effect of Iwazaki, we propose a perhaps stronger volume effect caused
by the induced time dependent electric dipole moment of neutrons.


title: A trace formula for the index of B-Fredholm operators

abstract:
  In this paper we define B-Fredholm elements in a Banach algebra $A$ modulo an
ideal $J$ of $A.$ When a trace function is given on the ideal $J,$ it generate
an index for B-Fredholm elements. In the case of a B-Fredholm operator $T$
acting on a Banach space, we prove that its usual index $ind(T)$ is equal to
the trace of the commutator $ [T, T_0],$ where $T_0$ is a Drazin inverse of $T$
modulo the ideal of finite rank operators, extending a Fedosov's trace formula
for Fredholm operators. In the case of a semi-simple Banach algebra, we prove a
punctured neighborhood theorem for the index.


title:
Exact Baker-Campbell-Hausdorff formula for the contact Heisenberg
  algebra

abstract:
  In this work we introduce the contact Heisenberg algebra which is the
restriction of the Jacobi algebra on contact manifolds to the linear and
constant functions. We give the exact expression of its corresponding
Baker-Campbell-Hausdorff formula. We argue that this result is relevant to the
quantization of contact systems.


title: Majorana box qubits

abstract:
  Quantum information protected by the topology of the storage medium is
expected to exhibit long coherence times. Another feature are topologically
protected gates generated through braiding of Majorana bound states. However,
braiding requires structures with branched topological segments which have
inherent difficulties in the semiconductor-superconductor heterostructures now
believed to host Majorana bound states. In this paper, we construct quantum
bits taking advantage of the topological protection and non-local properties of
Majorana bound states in a network of parallel wires, but without relying on
braiding for quantum gates. The elementary unit is made from three topological
wires, two wires coupled by a trivial superconductor and the third acting as an
interference arm. Coulomb blockade of the combined wires spawns a
fractionalized spin, non-locally addressable by quantum dots used for
single-qubit readout, initialization, and manipulation. We describe how the
same tools allow for measurement-based implementation of the Clifford gates, in
total making the architecture universal. Proof-of-principle demonstration of
topologically protected qubits using existing techniques is therefore within
reach.


title: Quantitative bound entanglement in two-qutrit states

abstract:
  Among the many facets of quantum correlations, bound entanglement has
remained one the most enigmatic phenomena, despite the fact that it was
discovered in the early days of quantum information. Even its detection has
proven to be difficult, let alone its precise quantitative characterization. In
this work, we present the exact quantification of entanglement for a
two-parameter family of highly symmetric two-qutrit mixed states, which
contains a sizable part of bound entangled states. We achieve this by
explicitly calculating the convex-roof extensions of the linear entropy as well
as the concurrence for every state within the family. Our results provide a
benchmark for future quantitative studies of bipartite entanglement in
higher-dimensional systems.


title:
Poisson approximation of counts of subgraphs in random intersection
  graphs

abstract:
  Random intersection graphs are characterized by three parameters: $n$, $m$
and $p$, where $n$ is the number of vertices, $m$ is the number of objects, and
$p$ is the probability that a given object is associated with a given vertex.
Two vertices in a random intersection graph are adjacent if and only if they
have an associated object in common. When $m=\lfloor n^\alpha\rfloor$ for
constant $\alpha$, we provide a condition, called {\em strictly
$\alpha$-balanced}, for the Poisson convergence of the number of induced copies
of a fixed subgraph.


title: Problems in additive number theory, V: Affinely inequivalent MSTD sets

abstract:
  An MSTD set is a finite set of integers with more sums than differences. It
is proved that, for infinitely many positive integers $k$, there are infinitely
many affinely inequivalent MSTD sets of cardinality $k$. There are several
related open problems.


title: Quintessential Scale Dependence from Separate Universe Simulations

abstract:
  By absorbing fluctuations into a local background, separate universe
simulations provide a powerful technique to characterize the response of
small-scale observables to the long-wavelength density fluctuations, for
example those of the power spectrum and halo mass function which lead to the
squeezed-limit $n$-point function and halo bias, respectively. Using
quintessence dark energy as the paradigmatic example, we extend these
simulation techniques to cases where non-gravitational forces in other sectors
establish a Jeans scale across which the growth of density fluctuations becomes
scale dependent. By characterizing the separate universes with matching
background expansion histories, we show that the power spectrum and mass
function responses depend on whether the long-wavelength mode is above or below
the Jeans scale. Correspondingly, the squeezed bispectrum and halo bias also
become scale dependent. Models of bias that are effectively local in the
density field at a single epoch, initial or observed, cannot describe this
effect which highlights the importance of temporal nonlocality in structure
formation. Validated by these quintessence tests, our techniques are applicable
to a wide range of models where the complex dynamics of additional fields
affect the clustering of matter in the linear regime and it would otherwise be
difficult to simulate their impact in the nonlinear regime.


title:
Thermodynamics of one-dimensional SU(4) and SU(6) fermions with
  attractive interactions

abstract:
  Motivated by advances in the manipulation and detection of ultracold atoms
with multiple internal degrees of freedom, we present a finite-temperature
lattice Monte Carlo calculation of the density and pressure equations of state,
as well as Tan's contact, of attractively interacting SU(4)- and
SU(6)-symmetric fermion systems in one spatial dimension. We also furnish a
nonperturbative proof of a universal relation whereby quantities computable in
the SU(2) case completely determine the virial coefficients of the SU($N_f$)
case. These one-dimensional systems are appealing because they can be
experimentally realized in highly constrained traps and because of the dominant
role played by correlations. The latter are typically nonperturbative and are
crucial for understanding ground states and quantum phase transitions. While
quantum fluctuations are typically overpowered by thermal ones in one and two
dimensions at any finite temperature, we find that quantum effects do leave
their imprint in thermodynamic quantities. Our calculations show that the
additional degrees of freedom, relative to the SU(2) case, provide a dramatic
enhancement of the density and pressure (in units of their noninteracting
counterparts) in a wide region around vanishing $\beta\mu$, where $\beta$ is
the inverse temperature and $\mu$ the chemical potential. As shown recently in
experiments, the thermodynamics we explore here can be measured in a controlled
and precise fashion in highly constrained traps and optical lattices. Our
results are a prediction for such experiments in one dimension with atoms of
high nuclear spin.


title:
Positions of the magnetoroton minima in the fractional quantum Hall
  effect

abstract:
  The multitude of excitations of the fractional quantum Hall state are very
accurately understood, microscopically, as excitations of composite fermions
across their Landau-like $\Lambda$ levels. In particular, the dispersion of the
composite fermion exciton, which is the lowest energy spin conserving neutral
excitation, displays filling-factor-specific minima called "magnetoroton"
minima. Simon and Halperin employed the Chern-Simons field theory of composite
fermions [Phys. Rev. B {\bf 48}, 17368 (1993)] to predict the magnetoroton
minima positions. Recently, Golkar \emph{et al.} [Phys. Rev. Lett. {\bf 117},
216403 (2016)] have modeled the neutral excitations as deformations of the
composite fermion Fermi sea, which results in a prediction for the positions of
the magnetoroton minima. Using methods of the microscopic composite fermion
theory we calculate the positions of the roton minima for filling factors up to
5/11 along the sequence $s/(2s+1)$ and find them to be in reasonably good
agreement with both the Chern-Simons field theory of composite fermions and
Golkar \emph{et al.}'s theory. We also find that the positions of the roton
minima are insensitive to the microscopic interaction in agreement with Golkar
\emph{et al.}'s theory. As a byproduct of our calculations, we obtain the
charge and neutral gaps for the fully spin polarized states along the sequence
$s/(2s\pm 1)$ in the lowest Landau level and the $n=1$ Landau level of
graphene.


title: Hierarchical Multiscale Recurrent Neural Networks

abstract:
  Learning both hierarchical and temporal representation has been among the
long-standing challenges of recurrent neural networks. Multiscale recurrent
neural networks have been considered as a promising approach to resolve this
issue, yet there has been a lack of empirical evidence showing that this type
of models can actually capture the temporal dependencies by discovering the
latent hierarchical structure of the sequence. In this paper, we propose a
novel multiscale approach, called the hierarchical multiscale recurrent neural
networks, which can capture the latent hierarchical structure in the sequence
by encoding the temporal dependencies with different timescales using a novel
update mechanism. We show some evidence that our proposed multiscale
architecture can discover underlying hierarchical structure in the sequences
without using explicit boundary information. We evaluate our proposed model on
character-level language modelling and handwriting sequence modelling.


title: Ramsey graphs induce subgraphs of many different sizes

abstract:
  A graph on $n$ vertices is said to be \emph{$C$-Ramsey} if every clique or
independent set of the graph has size at most $C \log n$. The only known
constructions of Ramsey graphs are probabilistic in nature, and it is generally
believed that such graphs possess many of the same properties as dense random
graphs. Here, we demonstrate one such property: for any fixed $C>0$, every
$C$-Ramsey graph on $n$ vertices induces subgraphs of at least $n^{2-o(1)}$
distinct sizes. This near-optimal result is closely related to two unresolved
conjectures, the first due to Erd\H{o}s and McKay and the second due to
Erd\H{o}s, Faudree and S\'{o}s, both from 1992.


title: Dyadic-probabilistic methods in bilinear analysis

abstract:
  We demonstrate and develop dyadic-probabilistic methods in connection with
non-homogeneous bilinear operators, namely singular integrals and square
functions. We develop the full non-homogeneous theory of bilinear singular
integrals using a modern point of view. The main result is a new global $Tb$
theorem for Calder\'on-Zygmund operators in this setting. Our main tools
include maximal truncations, adapted Cotlar type inequalities and suppression
and big piece methods.
  While proving our bilinear results we also advance and refine the linear
theory of Calder\'on-Zygmund operators by improving techniques and results. For
example, we simplify and make more efficient some non-homogeneous summing
arguments appearing in $T1$ type proofs. As a byproduct, we can manage with
ease quite general modulus of continuity in the kernel estimates. Our testing
conditions are also quite general by virtue of the big piece method of proof.


title:
Lyapunov Exponent and Out-of-Time-Ordered Correlator's Growth Rate in a
  Chaotic System

abstract:
  It was proposed recently that the out-of-time-ordered four-point correlator
(OTOC) may serve as a useful characteristic of quantum-chaotic behavior,
because in the semi-classical limit, $\hbar \to 0$, its rate of exponential
growth resembles the classical Lyapunov exponent. Here, we calculate the
four-point correlator, $C(t)$, for the classical and quantum kicked rotor -- a
textbook driven chaotic system -- and compare its growth rate at initial times
with the standard definition of the classical Lyapunov exponent. Using both
quantum and classical arguments, we show that the OTOC's growth rate and the
Lyapunov exponent are in general distinct quantities, corresponding to the
logarithm of phase-space averaged divergence rate of classical trajectories and
to the phase-space average of the logarithm, respectively. The difference
appears to be more pronounced in the regime of low kicking strength $K$, where
no classical chaos exists globally. In this case, the Lyapunov exponent quickly
decreases as $K \to 0$, while the OTOC's growth rate may decrease much slower
showing higher sensitivity to small chaotic islands in the phase space. We also
show that the quantum correlator as a function of time exhibits a clear
singularity at the Ehrenfest time $t_E$: transitioning from a time-independent
value of $t^{-1} \ln{C(t)}$ at $t < t_E$ to its monotonous decrease with time
at $t>t_E$. We note that the underlying physics here is the same as in the
theory of weak (dynamical) localization [Aleiner and Larkin, Phys. Rev. B 54,
14423 (1996); Tian, Kamenev, and Larkin, Phys. Rev. Lett. 93, 124101 (2004)]
and is due to a delay in the onset of quantum interference effects, which occur
sharply at a time of the order of the Ehrenfest time.


title: Tractable Bayesian variable selection: beyond normality

abstract:
  Bayesian variable selection often assumes normality, but the effects of model
misspecification are not sufficiently understood. There are sound reasons
behind this assumption, particularly for large $p$: ease of interpretation,
analytical and computational convenience. More flexible frameworks exist,
including semi- or non-parametric models, often at the cost of some
tractability. We propose a simple extension of the Normal model that allows for
skewness and thicker-than-normal tails but preserves tractability. It leads to
easy interpretation and a log-concave likelihood that facilitates optimization
and integration. We characterize asymptotically parameter estimation and Bayes
factor rates, in particular studying the effects of model misspecification.
Under suitable conditions misspecified Bayes factors are consistent and induce
sparsity at the same asymptotic rates than under the correct model. However,
the rates to detect signal are altered by an exponential factor, often
resulting in a loss of sensitivity. These deficiencies can be ameliorated by
inferring the error distribution from the data, a simple strategy that can
improve inference substantially. Our work focuses on the likelihood and can
thus be combined with any likelihood penalty or prior, but here we focus on
non-local priors to induce extra sparsity and ameliorate finite-sample effects
caused by misspecification. Our results highlight the practical importance of
focusing on the likelihood rather than solely on the prior, when it comes to
Bayesian variable selection. The methodology is available in R package `mombf'.


title: Thermometry for Laughlin States of Ultracold Atoms

abstract:
  Cooling atomic gases into strongly correlated quantum phases requires
estimates of the entropy to perform thermometry and establish viability. We
construct an ansatz partition function for models of Laughlin states of atomic
gases by combining high temperature series expansions with exact
diagonalization. Using the ansatz we find that entropies required to observe
Laughlin correlations with bosonic gases are within reach of current cooling
capabilities.


title: Automation of Pedestrian Tracking in a Crowded Situation

abstract:
  Studies on microscopic pedestrian requires large amounts of trajectory data
from real-world pedestrian crowds. Such data collection, if done manually,
needs tremendous effort and is very time consuming. Though many studies have
asserted the possibility of automating this task using video cameras, we found
that only a few have demonstrated good performance in very crowded situations
or from a top-angled view scene. This paper deals with tracking pedestrian
crowd under heavy occlusions from an angular scene. Our automated tracking
system consists of two modules that perform sequentially. The first module
detects moving objects as blobs. The second module is a tracking system. We
employ probability distribution from the detection of each pedestrian and use
Bayesian update to track the next position. The result of such tracking is a
database of pedestrian trajectories over time and space. With certain prior
information, we showed that the system can track a large number of people under
occlusion and clutter scene.


title:
Probing Gravitational Cat States in Canonical Quantum Theory vs
  Objective Collapse Theories

abstract:
  Using as a testbed the recently proposed "gravcat" experimental scheme in
[1], we compare the properties of gravitational cat states in three
descriptions: (1) canonical quantum theory (CQT) combined with the Newtonian
limit of GR, (2) objective collapse theories (OCTs) extended to the regime of
semiclassical Newtonian gravity, and (3) OCTs extended to incorporate quantized
Newtonian gravity. For the CQT approach, we follow the treatment of Hu and
Anastopoulos in [2]. For the OCTs, we consider the GRW, CSL, DP, and Karolyhazy
theories, based on the semiclassical approaches of Derakhshani [3] and
Tilloy-Diosi [4], respectively, and we consider the most straightforward
extension of the aforementioned OCTs to the regime of quantized Newtonian
gravity. We show that the gravitational cat scheme can, in principle,
experimentally discriminate the quantum jumps in gravitational cat states
predicted by the CQT approach and the quantized-gravity OCTs (which we show
make effectively the same predictions as each other), from the predictions of
the semiclassical-gravitational OCTs. We also show that the GRW and Karolyhazy
versions of semiclassical gravity (based on Derakhshani's approach) make
distinctly different predictions from the CSL and DP versions of semiclassical
gravity (based either on Derakhshani's approach or the Tilloy-Diosi approach).


title: Encoding spatial data into quantum observables

abstract:
  The focus of this work is a correspondence between the Hilbert space
operators on one hand, and doubly periodic generalized functions on the other.
The linear map that implements it, referred to as the Q-transform, enables a
direct application of the classical Harmonic Analysis in a study of quantum
systems. In particular, the Q-transform makes it possible to reinterpret the
dynamic of a quantum observable as a (typically nonlocal) dynamic of a
classical observable. From this point of view we carry out an analysis of an
open quantum system whose dynamics are governed by an asymptotically harmonic
Hamiltonian and compact type Lindblad operators. It is established that the
initial value problem of the equivalent nonlocal but classical evolution is
well posed in the appropriately chosen Sobolev spaces.
  The second set of results pertains to a generalization of the basic
Q-transform and highlights a certain type of asymptotic redundancy. This
phenomenon, referred to as the broadband redundancy, is a consequence of a
well-known property of the zeros of the Riemann zeta function, namely, the
uniform distribution modulo one of their ordinates. Its relevance to the
analysis of quantum dynamics is only a special instance of its utility in
harmonic analysis in general. It remains to be seen if the phenomenon is
significant also in the physical sense, but it appears well-justified---in
particular, by the results presented here---to pose such a question.


title:
The SLUGGS Survey: revisiting the correlation between X-ray luminosity
  and total mass of massive early-type galaxies

abstract:
  Here we utilise recent measures of galaxy total dynamical mass and X-ray gas
luminosities (L$_{X,Gas}$) for a sample of 29 massive early-type galaxies from
the SLUGGS survey to probe L$_{X,Gas}$--mass scaling relations. In particular,
we investigate scalings with stellar mass, dynamical mass within 5 effective
radii (R$_e$) and total virial mass. We also compare these relations with
predictions from $\Lambda$CDM simulations. We find a strong linear relationship
between L$_{X,Gas}$ and galaxy dynamical mass within 5 R$_e$, which is
consistent with the recent cosmological simulations of Choi et al. that
incorporate mechanical heating from AGN. We conclude that the gas surrounding
massive early-type galaxies was shock heated as it fell into collapsing dark
matter halos so that L$_{X,Gas}$ is primarily driven by the depth of a galaxy's
potential well. Heating by an AGN plays an important secondary role in
determining L$_{X,Gas}$.


title: The Effect of Fiber Collisions on the Galaxy Power Spectrum Multipole

abstract:
  Fiber-fed multi-object spectroscopic surveys, with their ability to collect
an unprecedented number of redshifts, currently dominate large-scale structure
studies. However, physical constraints limit these surveys from successfully
collecting redshifts from galaxies too close to each other on the focal plane.
This ultimately leads to significant systematic effects on galaxy clustering
measurements. Using simulated mock catalogs, we demonstrate that fiber
collisions have a significant impact on the power spectrum, $P(k)$, monopole
and quadrupole that exceeds sample variance at scales smaller than
$k\sim0.1~h/Mpc$.
  We present two methods to account for fiber collisions in the power spectrum.
The first, statistically reconstructs the clustering of fiber collided galaxy
pairs by modeling the distribution of the line-of-sight displacements between
them. It also properly accounts for fiber collisions in the shot-noise
correction term of the $P(k)$ estimator. Using this method, we recover the true
$P(k)$ monopole of the mock catalogs with residuals of $<0.5\%$ at
$k=0.3~h/Mpc$ and $<4\%$ at $k=0.83~h/Mpc$ -- a significant improvement over
existing correction methods. The quadrupole, however, does not improve
significantly.
  The second method models the effect of fiber collisions on the power spectrum
as a convolution with a configuration space top-hat function that depends on
the physical scale of fiber collisions. It directly computes theoretical
predictions of the fiber-collided $P(k)$ multipoles and reduces the influence
of smaller scales to a set of nuisance parameters. Using this method, we
reliably model the effect of fiber collisions on the monopole and quadrupole
down to the scale limits of theoretical predictions. The methods we present in
this paper will allow us to robustly analyze galaxy power spectrum multipole
measurements to much smaller scales than previously possible.


title:
The impact of mass segregation and star-formation on the rates of
  gravitational-wave sources from extreme mass ratio inspirals

abstract:
  Compact stellar objects inspiralling into massive black holes (MBHs) in
galactic nuclei are some of the most promising gravitational wave (GWs) sources
for next generation GW-detectors. The rates of such extreme mass ratio
inspirals (EMRIs) depend on the dynamics and distribution of compact objects
around the MBH. Here we study the impact of mass-segregation processes on EMRI
rates. In particular, we provide the expected mass function of EMRIs, given an
initial mass function of stellar BHs (SBHs), and relate it to the
mass-dependent detection rate of EMRIs. We then consider the role of star
formation on the distribution of compact objects and its implication on EMRI
rates. We find that the existence of a wide spectrum of SBH masses lead to the
overall increase of EMRI rates, and to high rates of the EMRIs from the
most-massive SBHs. However, it also leads to a relative quenching of EMRI rates
from lower-mass SBHs, and together produces a steep dependence of the EMRI mass
function on the highest-mass SBHs. Star-formation history plays a relatively
small role in determining the EMRI rates of SBHs, since most of them migrate
close to the MBH through mass-segregation rather than forming in-situ. However,
the EMRI rate of neutron stars can be significantly increased when they form
in-situ close to the MBH, as they can inspiral before relaxation processes
significantly segregates them outwards. A reverse but weaker effect of
decreasing the EMRI rates from neutron stars and white dwarfs occurs when
star-formation proceeds far from the MBH.


title:
Comparative performance of selected variability detection techniques in
  photometric time series

abstract:
  Photometric measurements are prone to systematic errors presenting a
challenge to low-amplitude variability detection. In search for a
general-purpose variability detection technique able to recover a broad range
of variability types including currently unknown ones, we test 18 statistical
characteristics quantifying scatter and/or correlation between brightness
measurements. We compare their performance in identifying variable objects in
seven time series data sets obtained with telescopes ranging in size from a
telephoto lens to 1m-class and probing variability on time-scales from minutes
to decades. The test data sets together include lightcurves of 127539 objects,
among them 1251 variable stars of various types and represent a range of
observing conditions often found in ground-based variability surveys. The real
data are complemented by simulations. We propose a combination of two indices
that together recover a broad range of variability types from photometric data
characterized by a wide variety of sampling patterns, photometric accuracies,
and percentages of outlier measurements. The first index is the interquartile
range (IQR) of magnitude measurements, sensitive to variability irrespective of
a time-scale and resistant to outliers. It can be complemented by the ratio of
the lightcurve variance to the mean square successive difference, 1/h, which is
efficient in detecting variability on time-scales longer than the typical time
interval between observations. Variable objects have larger 1/h and/or IQR
values than non-variable objects of similar brightness. Another approach to
variability detection is to combine many variability indices using principal
component analysis. We present 124 previously unknown variable stars found in
the test data.


title:
Radiative transfer in disc galaxies $-$ V. The accuracy of the KB
  approximation

abstract:
  We investigate the accuracy of an approximate radiative transfer technique
that was first proposed by Kylafis & Bahcall (hereafter the KB approximation)
and has been popular in modelling dusty late-type galaxies. We compare
realistic galaxy models calculated with the KB approximation with those of a
three-dimensional Monte Carlo radiative transfer code SKIRT. The SKIRT code
fully takes into account of the contribution of multiple scattering whereas the
KB approximation calculates only single scattered intensity and multiple
scattering components are approximated. We find that the KB approximation gives
fairly accurate results if optically thin, face-on galaxies are considered.
However, for highly inclined ($i \gtrsim 85^{\circ}$) and/or optically thick
(central face-on optical depth $\gtrsim1$) galaxy models, the approximation can
give rise to substantial errors, sometimes, up to $\gtrsim 40\%$. Moreover, it
is also found that the KB approximation is not always physical, sometimes
producing infinite intensities at lines of sight with high optical depth in
edge-on galaxy models. There is no "simple recipe" to correct the errors of the
KB approximation that is universally applicable to any galaxy models.
Therefore, it is recommended that the full radiative transfer calculation be
used, even though it's slower than the KB approximation.


title: Shaken and Stirred: The Milky Way's Dark Substructures

abstract:
  The predicted abundance and properties of the low-mass substructures embedded
inside larger dark matter haloes differ sharply among alternative dark matter
models. Too small to host galaxies themselves, these subhaloes may still be
detected via gravitational lensing, or via perturbations of the Milky Way's
globular cluster streams and its stellar disk. Here we use the Apostle
cosmological simulations to predict the abundance and the spatial and velocity
distributions of subhaloes in the range 10^6.5-10^8.5 solar masses inside
haloes of mass ~ 10^12 solar masses in LCDM. Although these subhaloes are
themselves devoid of baryons, we find that baryonic effects are important.
Compared to corresponding dark matter only simulations, the loss of baryons
from subhaloes and stronger tidal disruption due to the presence of baryons
near the centre of the main halo, reduce the number of subhaloes by ~ 1/4 to
1/2, independently of subhalo mass, but increasingly towards the host halo
centre. We also find that subhaloes have non-Maxwellian orbital velocity
distributions, with centrally rising velocity anisotropy and positive velocity
bias which reduces the number of low-velocity subhaloes, particularly near the
halo centre. We parameterise the predicted population of subhaloes in terms of
mass, galactocentric distance, and velocities. We discuss implications of our
results for the prospects of detecting dark matter substructures and for
possible inferences about the nature of dark matter.


title: Zooming on the internal structure of $z\simeq6$ galaxies

abstract:
  We present zoom-in, AMR, high-resolution ($\simeq 30$ pc) simulations of
high-redshift ($z \simeq 6$) galaxies with the aim of characterizing their
internal properties and interstellar medium. Among other features, we adopt a
star formation model based on a physically-sound molecular hydrogen
prescription, and introduce a novel scheme for supernova feedback, stellar
winds and dust-mediated radiation pressure. In the zoom-in simulation the
target halo hosts "Dahlia", a galaxy with a stellar mass $M_*=1.6\times
10^{10}$M$_\odot$, representative of a typical $z\sim 6$ Lyman Break Galaxy.
Dahlia has a total H2 mass of $10^{8.5}$M$_\odot$, that is mainly concentrated
in a disk-like structure of effective radius $\simeq 0.6$ kpc and scale height
$\simeq 200$ pc. Frequent mergers drive fresh gas towards the center of the
disk, sustaining a star formation rate per unit area of $\simeq 15 $M$_\odot$
yr$^{-1}$ kpc$^{-2}$. The disk is composed by dense ($n \gtrsim 25$ cm$^{-3}$),
metal-rich ($Z \simeq 0.5 $ Z$_\odot$) gas, that is pressure-supported by
radiation. We compute the $158\mu$m [CII] emission arising from {Dahlia}, and
find that $\simeq 95\%$ of the total [CII] luminosity
($L_{[CII]}\simeq10^{7.5}$ L$_\odot$) arises from the H2 disk. Although $30\%$
of the CII mass is transported out of the disk by outflows, such gas negligibly
contributes to [CII] emission, due to its low density ($n \lesssim 10$
cm$^{-3}$) and metallicity ($Z\lesssim 10^{-1}$Z$_\odot$). Dahlia is
under-luminous with respect to the local [CII]-SFR relation; however, its
luminosity is consistent with upper limits derived for most $z\sim6$ galaxies.


title: A stellar-mass black hole population in the globular cluster NGC 6101?

abstract:
  Dalessandro et al. observed a similar distribution for blue straggler stars
and main-sequence turn-off stars in the Galactic globular cluster NGC 6101, and
interpreted this feature as an indication that this cluster is not
mass-segregated. Using direct N-body simulations, we find that a significant
amount of mass segregation is expected for a cluster with the mass, radius and
age of NGC 6101. Therefore, the absence of mass segregation cannot be explained
by the argument that the cluster is not yet dynamically evolved. By varying the
retention fraction of stellar-mass black holes, we show that segregation is not
observable in clusters with a high black hole retention fraction (>50% after
supernova kicks and >50% after dynamical evolution). Yet all model clusters
have the same amount of mass segregation in terms of the decline of the mean
mass of stars and remnants with distance to the centre. We also discuss how
kinematics can be used to further constrain the presence of a stellar-mass
black hole population and distinguish it from the effect of an
intermediate-mass black hole. Our results imply that the kick velocities of
black holes are lower than those of neutron stars. The large retention fraction
during its dynamical evolution can be explained if NGC 6101 formed with a large
initial radius in a Milky Way satellite.


title:
Seeding the Galactic Centre gas stream: gravitational instabilities set
  the initial conditions for the formation of protocluster clouds

abstract:
  Star formation within the Central Molecular Zone (CMZ) may be intimately
linked to the orbital dynamics of the gas. Recent models suggest that star
formation within the dust ridge molecular clouds (from G0.253+0.016 to Sgr B2)
follows an evolutionary time sequence, triggered by tidal compression during
their preceding pericentre passage. Given that these clouds are the most likely
precursors to a generation of massive stars and extreme star clusters, this
scenario would have profound implications for constraining the time-evolution
of star formation. In this Letter, we search for the initial conditions of the
protocluster clouds, focusing on the kinematics of gas situated upstream from
pericentre. We observe a highly-regular corrugated velocity field in
$\{l,\,v_{\rm LSR}\}$ space, with amplitude and wavelength $A=3.7\,\pm\,0.1$
kms$^{-1}$ and $\lambda_{\rm vel, i}=22.5\,\pm\,0.1$ pc, respectively. The
extremes in velocity correlate with a series of massive
($\sim10^{4}$M$_{\odot}$) and compact ($R_{\rm eq}\sim2$ pc), quasi-regularly
spaced ($\sim8$ pc), molecular clouds. The corrugation wavelength and cloud
separation closely agree with the predicted Toomre ($\sim17$ pc) and Jeans
($\sim6$ pc) lengths, respectively. We conclude that gravitational
instabilities are driving the condensation of molecular clouds within the
Galactic Centre gas stream. Furthermore, we speculate these seeds are the
historical analogue of the dust-ridge molecular clouds, representing the
initial conditions of star and cluster formation in the CMZ.


title: Applying Relativistic Reconnection to Blazar Jets

abstract:
  Rapid and luminous flares of non-thermal radiation observed in blazars
require an efficient mechanism of energy dissipation and particle acceleration
in relativistic active galactic nuclei (AGN) jets. Particle acceleration in
relativistic magnetic reconnection is being actively studied by kinetic
numerical simulations. Relativistic reconnection produces hard power-law
electron energy distributions N(gamma) = N_0 gamma^(-p) exp(-gamma/gamma_max)
with index p -> 1 and exponential cut-off Lorentz factor gamma_max ~ sigma in
the limit of magnetization sigma = B^2/(4 pi w) >> 1 (where w is the
relativistic enthalpy density). Reconnection in electron-proton plasma can
additionally boost gamma_max by the mass ratio m_p/m_e. Hence, in order to
accelerate particles to gamma_max ~ 10^6 in the case of BL Lacs, reconnection
should proceed in plasma of very high magnetization sigma_max >~ 10^3. On the
other hand, moderate mean jet magnetization values are required for magnetic
bulk acceleration of relativistic jets, sigma_mean ~ Gamma_j <~ 20 (where
Gamma_j is the jet bulk Lorentz factor). I propose that the systematic
dependence of gamma_max on blazar luminosity class -- the blazar sequence --
may result from a systematic trend in sigma_max due to homogeneous loading of
leptons by pair creation regulated by the energy density of high-energy
external radiation fields. At the same time, relativistic AGN jets should be
highly inhomogeneous due to filamentary loading of protons, which should
determine the value of sigma_mean roughly independently of the blazar class.


title: Brane Brick Models in the Mirror

abstract:
  Brane brick models are Type IIA brane configurations that encode the $2d$
$\mathcal{N}=(0,2)$ gauge theories on the worldvolume of D1-branes probing
toric Calabi-Yau 4-folds. We use mirror symmetry to improve our understanding
of this correspondence and to provide a systematic approach for constructing
brane brick models starting from geometry. The mirror configuration consists of
D5-branes wrapping 4-spheres and the gauge theory is determined by how they
intersect. We also explain how $2d$ $(0,2)$ triality is realized in terms of
geometric transitions in the mirror geometry. Mirror symmetry leads to a
geometric unification of dualities in different dimensions, where the order of
duality is $n-1$ for a Calabi-Yau $n$-fold. This makes us conjecture the
existence of a quadrality symmetry in $0d$. Finally, we comment on how the
M-theory lift of brane brick models connects to the classification of $2d$
$(0,2)$ theories in terms of 4-manifolds.


title: Quantum confinement on non-complete Riemannian manifolds

abstract:
  We consider the quantum completeness problem, i.e. the problem of confining
quantum particles, on a non-complete Riemannian manifold $M$ equipped with a
smooth measure $\omega$, possibly degenerate or singular near the metric
boundary of $M$, and in presence of a real-valued potential $V\in
L^2_{\mathrm{loc}}(M)$. The main merit of this paper is the identification of
an intrinsic quantity, the effective potential $V_{\mathrm{eff}}$, which allows
to formulate simple criteria for quantum confinement. Let $\delta$ be the
distance from the possibly non-compact metric boundary of $M$. A simplified
version of the main result guarantees quantum completeness if $V\ge -c\delta^2$
far from the metric boundary and \[
  V_{\mathrm{eff}}+V\ge \frac3{4\delta^2}-\frac{\kappa}{\delta}, \qquad
\text{close to the metric boundary}. \] These criteria allow us to: (i) obtain
quantum confinement results for measures with degeneracies or singularities
near the metric boundary of $M$; (ii) generalize the
Kalf-Walter-Schmincke-Simon Theorem for strongly singular potentials to the
Riemannian setting for any dimension of the singularity; (iii) give the first,
to our knowledge, curvature-based criteria for self-adjointness of the
Laplace-Beltrami operator; (iv) prove, under mild regularity assumptions, that
the Laplace-Beltrami operator in almost-Riemannian geometry is essentially
self-adjoint, partially settling a conjecture formulated in [Boscain, Laurent -
Ann. Inst. Fourier, 2013] .


title: The Good, the Bad, and the Ugly of Gravity and Information

abstract:
  Various contenders for a complete theory of quantum gravity are at odds with
each other. This is in particular seen in the ways they relate to information
and black holes, and how to effectively treat quantization of the background
spacetime. Modern perspectives on black hole evaporation suggest that quantum
gravity effects in the near-horizon region can perturb the local geometry. The
approaches differ, however, in the time scale on which one can expect these
effects to become important. This panel session presents three points of view
on these problems, and considers the ultimate prospect of observational tests
in the near future.


title:
Effects of Defects and Dephasing on Charge and Spin Currents in
  Two-Dimensional Topological Insulators

abstract:
  Using the non-equilibrium Keldysh Green's function formalism, we investigate
the effect of defects on the electronic structure and transport properties of
two-dimensional topological insulators (TI). We demonstrate how the spatial
flow of charge changes between the topologically protected edge and bulk states
and show that elastically and inelastically scattering defects that preserve
the time reversal symmetry of the TI lead to qualitatively different effects on
the TI's local electronic structure and its transport properties. Moreover, we
show that the recently predicted ability to create highly spin-polarized
currents by breaking the time-reversal symmetry of the TI via magnetic defects
[Phys. Rev. B 93, 081401 (2016)] is robust against the inclusion of a Rashba
spin-orbit interaction and the effects of dephasing, and remains unaffected by
changes over a wide range of the TI's parameters. We discuss how the sign of
the induced spin currents changes under symmetry operations, such as reversal
of bias and gate voltages, or spatial reflections. Finally, we show that the
insight into the interplay between topology and symmetry of the magnetic
defects can be employed for the creation of novel quantum phenomena, such as
highly localized magnetic fields inside the TI.


title: The Complexity of Identifying Ryu-Takayanagi Surfaces in AdS3/CFT2

abstract:
  We present a constructive algorithm for the determination of Ryu-Takayanagi
surfaces in AdS3/CFT2 which exploits previously noted connections between
holographic entanglement entropy and max-flow/min-cut. We then characterize its
complexity as a polynomial time algorithm.


title: Insights from probability distribution functions of intensity maps

abstract:
  In the next few years, intensity-mapping surveys that target lines such as
CO, Ly$\alpha$, and CII stand to provide powerful probes of high-redshift
astrophysics. However, these line emissions are highly non-Gaussian, and so the
typical power-spectrum methods used to study these maps will leave out a
significant amount of information. We propose a new statistic, the probability
distribution of voxel intensities, which can access this extra information.
Using a model of a CO intensity map at $z\sim3$ as an example, we demonstrate
that this voxel intensity distribution (VID) provides substantial constraining
power beyond what is obtainable from the power spectrum alone. We find that a
future survey similar to the planned COMAP Full experiment could constrain the
CO luminosity function to order $\sim10\%$. We also explore the effects of
contamination from continuum emission, interloper lines, and gravitational
lensing on our constraints and find that the VID statistic retains significant
constraining power even in pessimistic scenarios.


title:
Absence of nematic ordering transition in a diamond lattice: Application
  to $FeSc_2S_4$

abstract:
  Recent neutron scattering observations by Plumb et al. [1] reveal that the
ground state of $FeSc_2S_4$ is magnetic with two distinct Fe environments,
instead of a quantum spin liquid as had been previously thought. Starting with
the relevant O(N)-symmetric vector model of $FeSc_2S_4$, we study how the
discrete ($Z_2$) and continuous rotational symmetries are successively broken,
yielding nematic and ordered phases. At high temperatures, we find that the
nematic order parameter falls as $T^{-\gamma}$ ($\gamma>0$), and therefore,
$FeSc_2S_4$ lacks any distinct nematic ordering temperature. This feature
indicates that the three-dimensional diamond lattice of $FeSc_2S_4$ is highly
susceptible to the breaking of Ising symmetries, and explains the two distinct
Fe environments that is present even at high temperatures, as seen by
M\"ossbauer and far infrared optical spectroscopy.


title: Monte Carlo calculations of the finite density Thirring model

abstract:
  We present results of the numerical simulation of the two-dimensional
Thirring model at finite density and temperature. The severe sign problem is
dealt with by deforming the domain of integration into complex field space.
This is the first example where a fermionic sign problem is solved in a quantum
field theory by using the holomorphic gradient flow approach, a generalization
of the Lefschetz thimble method.


title: Bondi-Sachs Formalism

abstract:
  The Bondi-Sachs formalism of General Relativity is a metric-based treatment
of the Einstein equations in which the coordinates are adapted to the null
geodesics of the spacetime. It provided the first convincing evidence that
gravitational radiation is a nonlinear effect of general relativity and that
the emission of gravitational waves from an isolated system is accompanied by a
mass loss from the system. The asymptotic behaviour of the Bondi-Sachs metric
revealed the existence of the symmetry group at null infinity, the
Bondi-Metzner-Sachs group, which turned out to be larger than the Poincare
group.


title:
The visibility based Tapered Gridded Estimator (TGE) for the redshifted
  21-cm power spectrum

abstract:
  We present the improved visibility based Tapered Gridded Estimator (TGE) for
the power spectrum of the diffuse sky signal. The visibilities are gridded to
reduce the computation, and tapered through a convolution to suppress the
contribution from the outer regions of the telescope's field of view. The TGE
also internally estimates the noise bias, and subtracts this out to give an
unbiased estimate of the power spectrum. An earlier version of the 2D TGE for
the angular power spectrum $C_{\ell}$ is improved and then extended to obtain
the 3D TGE for the power spectrum $P({\bf k})$ of the 21-cm brightness
temperature fluctuations. Analytic formulas are also presented for predicting
the variance of the binned power spectrum. The estimator and its variance
predictions are validated using simulations of $150 \, {\rm MHz}$ GMRT
observations. We find that the estimator accurately recovers the input model
for the 1D Spherical Power Spectrum $P(k)$ and the 2D Cylindrical Power
Spectrum $P(k_\perp,k_\parallel)$, and the predicted variance is also in
reasonably good agreement with the simulations.


title: Wave propagation on microstate geometries

abstract:
  Supersymmetric microstate geometries were recently conjectured to be
nonlinearly unstable due to numerical and heuristic evidence, based on the
existence of very slowly decaying solutions to the linear wave equation on
these backgrounds. In this paper, we give a thorough mathematical treatment of
the linear wave equation on both two and three charge supersymmetric microstate
geometries, finding a number of surprising results. In both cases we prove that
solutions to the wave equation have uniformly bounded local energy, despite the
fact that three charge microstates possess an ergoregion; these geometries
therefore avoid Friedman's "ergosphere instability". In fact, in the three
charge case we are able to construct solutions to the wave equation with local
energy that neither grows nor decays, although this data must have nontrivial
dependence on the Kaluza-Klein coordinate. In the two charge case we construct
quasimodes and use these to bound the uniform decay rate, showing that the only
possible uniform decay statements on these backgrounds have very slow decay
rates. We find that these decay rates are sub-logarithmic, verifying the
numerical results of Eperon et al. The same construction can be made in the
three charge case, and in both cases the data for the quasimodes can be chosen
to have trivial dependence on the Kaluza-Klein coordinates.


title:
Linking long-term planetary $N$-body simulations with periodic orbits:
  application to white dwarf pollution

abstract:
  Mounting discoveries of debris discs orbiting newly-formed stars and white
dwarfs (WDs) showcase the importance of modeling the long-term evolution of
small bodies in exosystems. WD debris discs are in particular thought to form
from very long-term (0.1-5.0 Gyr) instability between planets and asteroids.
However, the time-consuming nature of $N$-body integrators which accurately
simulate motion over Gyrs necessitates a judicious choice of initial
conditions. The analytical tools known as \textit{periodic orbits} can
circumvent the guesswork. Here, we begin a comprehensive analysis directly
linking periodic orbits with $N$-body integration outcomes with an extensive
exploration of the planar circular restricted three-body problem (CRTBP) with
an outer planet and inner asteroid near or inside of the $2$:$1$ mean motion
resonance. We run nearly 1000 focused simulations for the entire age of the
Universe (14 Gyr) with initial conditions mapped to the phase space locations
surrounding the unstable and stable periodic orbits for that commensurability.
In none of our simulations did the planar CRTBP architecture yield a
long-timescale ($\gtrsim 0.25$% of the age of the Universe) asteroid-star
collision. The pericentre distance of asteroids which survived beyond this
timescale ($\approx 35$ Myr) varied by at most about 60%. These results help
affirm that collisions occur too quickly to explain WD pollution in the planar
CRTBP $2$:$1$ regime, and highlight the need for further periodic orbit studies
with the eccentric and inclined TBP architectures and other significant orbital
period commensurabilities.


title: Asymptotically anti-de Sitter Proca Stars

abstract:
  We show that complex, massive spin-1 fields minimally coupled to Einstein's
gravity with a negative cosmological constant, admit asymptotically anti-de
Sitter self-gravitating solutions. Focusing on 4-dimensional spacetimes, we
start by obtaining analytical solutions in the test-field limit, where the
Proca field equations can be solved in a fixed anti-de Sitter background, and
then find fully non-linear solutions numerically. These solutions are a natural
extension of the recently found asymptotically flat Proca stars and share
similar properties with scalar boson stars. In particular, we show that they
are stable against spherically symmetric linear perturbations for a range of
fundamental frequencies limited by their point of maximum mass. We finish with
an overview of the behavior of Proca stars in $5$ dimensions.


title: Boundary Operators in Effective String Theory

abstract:
  Various universal features of relativistic rotating strings depend on the
organization of allowed local operators on the worldsheet. In this paper, we
study the set of Neumann boundary operators in effective string theory, which
are relevant for the controlled study of open relativistic strings with freely
moving endpoints. Relativistic open strings are thought to encode the dynamics
of confined quark-antiquark pairs in gauge theories in the planar
approximation. Neumann boundary operators can be organized by their behavior
under scaling of the target space coordinates X, and the set of allowed
X-scaling exponents is bounded above by +1/2 and unbounded below. Negative
contributions to X-scalings come from powers of a single invariant, or
"dressing" operator, which is bilinear in the embedding coordinates. In
particular, we show that all Neumann boundary operators are dressed by
quarter-integer powers of this invariant, and we demonstrate how this rule
arises from various ways of regulating the short-distance singularities of the
effective theory.


title:
SDSS IV MaNGA - The spatially resolved transition from star formation to
  quiescence

abstract:
  Using spatially resolved spectroscopy from SDSS-IV MaNGA we have demonstrated
that low ionisation emission line regions (LIERs) in local galaxies result from
photoionisation by hot evolved stars, not active galactic nuclei. LIERs are
ubiquitous in both quiescent galaxies and in the central regions of galaxies
where star formation takes place at larger radii. We refer to these two classes
of galaxies as extended LIER (eLIER) and central LIER (cLIER) galaxies
respectively. cLIERs are late type galaxies located around the green valley, in
the transition region between the star formation main sequence and quiescent
galaxies. These galaxies display regular disc rotation in both stars and gas,
although featuring a higher central stellar velocity dispersion than star
forming galaxies of the same mass. cLIERs are consistent with being slowly
quenched inside-out; the transformation is associated with massive bulges,
pointing towards the importance of bulge growth via secular evolution. eLIERs
are morphologically early types and are indistinguishable from passive galaxies
devoid of line emission in terms of their stellar populations, morphology and
central stellar velocity dispersion. Ionised gas in eLIERs shows both disturbed
and disc-like kinematics. When a large-scale flow/rotation is observed in the
gas, it is often misaligned relative to the stellar component. These features
indicate that eLIERs are passive galaxies harbouring a residual cold gas
component, acquired mostly via external accretion. Importantly, quiescent
galaxies devoid of line emission reside in denser environments and have
significantly higher satellite fraction than eLIERs. Environmental effects thus
represent the likely cause for the existence of line-less galaxies on the red
sequence.


title: Decoherence Can Relax Cosmic Acceleration

abstract:
  In this work we investigate the semi-classical backreaction for a quantised
conformal scalar field and classical vacuum energy. In contrast to the usual
approximation of a closed system, our analysis includes an environmental sector
such that a quantum-to-classical transition can take place. We show that when
the system decoheres into a mixed state with particle number as the classical
observable de Sitter space is destabilized, which is observable as a gradually
decreasing Hubble rate. In particular we show that at late times this mechanism
can drive the curvature of the Universe to zero and has an interpretation as
the decay of the vacuum energy demonstrating that quantum effects can be
relevant for the fate of the Universe.


title: Angular momentum evolution of galaxies in EAGLE

abstract:
  We use the EAGLE cosmological hydrodynamic simulation suite to study the
specific angular momentum of galaxies, $j$, with the aims of (i) investigating
the physical causes behind the wide range of $j$ at fixed mass and (ii)
examining whether simple, theoretical models can explain the seemingly complex
and non-linear nature of the evolution of $j$. We find that $j$ of the stars,
$j_{\rm stars}$, and baryons, $j_{\rm bar}$, are strongly correlated with
stellar and baryon mass, respectively, with the scatter being highly correlated
with morphological proxies such as gas fraction, stellar concentration, (u-r)
intrinsic colour, stellar age and the ratio of circular velocity to velocity
dispersion. We compare with available observations at $z=0$ and find excellent
agreement. We find that $j_{\rm bar}$ follows the theoretical expectation of an
isothermal collapsing halo under conservation of specific angular momentum to
within $\approx 50$%, while the subsample of rotation-supported galaxies are
equally well described by a simple model in which the disk angular momentum is
just enough to maintain marginally stable disks. We extracted evolutionary
tracks of the stellar spin parameter of EAGLE galaxies and found that the fate
of their $j_{\rm stars}$ at $z=0$ depends sensitively on their star formation
and merger histories. From these tracks, we identified two distinct physical
channels behind low $j_{\rm stars}$ galaxies at $z=0$: (i) galaxy mergers, and
(ii) early star formation quenching. The latter can produce galaxies with low
$j_{\rm stars}$ and early-type morphologies even in the absence of mergers.


title:
Do galaxy global relationships emerge from local ones? The SDSS IV MaNGA
  surface mass density-metallicity relation

abstract:
  We present the stellar surface mass density {\it vs.} gas metallicity
($\Sigma_*-Z$) relation for more than 500,000 spatially-resolved star-forming
resolution elements (spaxels) from a sample of 653 disk galaxies included in
the SDSS IV MaNGA survey. We find a tight relation between these local
properties, with higher metallicities as the surface density increases. This
relation extends over three orders of magnitude in the surface mass density and
a factor of four in metallicity. We show that this local relationship can
simultaneously reproduce two well-known properties of disk galaxies: their
global mass-metallicity relationship {\it and} their radial metallicity
gradients. We also find that the $\Sigma_* - Z$ relation is largely independent
of the galaxy's total stellar mass and specific star-formation rate (sSFR),
except at low stellar mass and high sSFR. These results suggest that in the
present-day universe local properties play a key role in determining the
gas-phase metallicity in typical disk galaxies.


title: Partial-Wave Analysis of Nucleon-Nucleon Elastic Scattering Data

abstract:
  Energy-dependent and single-energy fits to the existing nucleon-nucleon
database have been updated to incorporate recent measurements. The fits cover a
region from threshold to 3 GeV, in the laboratory kinetic energy, for
proton-proton scattering, with an upper limit of 1.3 GeV for neutron-proton
scattering. Experiments carried out at the COSY-WASA and COSY-ANKE facilities
have had a significant impact on the partial-wave solutions. Results are
discussed in terms of both partial-wave and direct reconstruction amplitudes.


title:
GRB 980425 host: [CII], [OI] and CO lines reveal recent enhancement of
  star formation due to atomic gas inflow

abstract:
  We have recently suggested that gas accretion can be studied using host
galaxies of gamma-ray bursts (GRBs). We obtained the first ever far-infrared
(FIR) line observations of a GRB host, namely Herschel/PACS resolved [CII] 158
um and [OI] 63 um spectroscopy, as well as APEX CO(2-1) and ALMA CO(1-0)
observations of the GRB 980425 host. It has elevated [CII]/FIR and [OI]/FIR
ratios and higher values of star formation rate (SFR) derived from line ([CII],
[OI], Ha) than from continuum (UV, IR, radio) indicators. [CII] emission
exhibits a normal morphology, peaking at the galaxy center, whereas [OI] is
concentrated close to the GRB position and the nearby Wolf-Rayet region. The
high [OI] flux indicates high radiation field and gas density. The [CII]/CO
luminosity ratio of the GRB 980425 host is close to the highest values found
for local star-forming galaxies. Its CO-derived molecular gas mass is low given
its SFR and metallicity, but the [CII]-derived molecular gas mass is close to
the expected value. The [OI] and HI concentrations, and the high radiation
field and density are consistent with the hypothesis of a very recent (at most
a few tens of Myr ago) inflow of atomic gas triggering star formation. Dust has
not had time to build up (explaining high line-to-continuum ratios). Such a
recent enhancement of star-formation would indeed manifest itself in high
SFR_line/SFR_continuum ratios, because the line indicators are sensitive only
to recent (<10 Myr) activity, whereas the continuum indicators measure the SFR
averaged over much longer periods (~100 Myr). Other GRB hosts exhibit a mean
SFR_line/SFR_continuum of 1.74+-0.32. This is consistent with a very recent
enhancement of star formation being common among GRB hosts, so galaxies which
have recently experienced inflow of gas may preferentially host stars exploding
as GRBs. Hence GRB hosts may be used to investigate recent gas accretion.


title: Human pose estimation via Convolutional Part Heatmap Regression

abstract:
  This paper is on human pose estimation using Convolutional Neural Networks.
Our main contribution is a CNN cascaded architecture specifically designed for
learning part relationships and spatial context, and robustly inferring pose
even for the case of severe part occlusions. To this end, we propose a
detection-followed-by-regression CNN cascade. The first part of our cascade
outputs part detection heatmaps and the second part performs regression on
these heatmaps. The benefits of the proposed architecture are multi-fold: It
guides the network where to focus in the image and effectively encodes part
constraints and context. More importantly, it can effectively cope with
occlusions because part detection heatmaps for occluded parts provide low
confidence scores which subsequently guide the regression part of our network
to rely on contextual information in order to predict the location of these
parts. Additionally, we show that the proposed cascade is flexible enough to
readily allow the integration of various CNN architectures for both detection
and regression, including recent ones based on residual learning. Finally, we
illustrate that our cascade achieves top performance on the MPII and LSP data
sets. Code can be downloaded from http://www.cs.nott.ac.uk/~psxab5/


title: A remark on the irregularity complex

abstract:
  We prove that, for a good meromorphic flat bundle with poles along a divisor
with normal crossings, the restriction of the irregularity complex to each
natural stratum of this divisor only depends on the formal flat bundle along
this stratum. This answers a question raised by J.-B. Teyssier. This version
takes into account the published erratum.


title:
The Small Field Parabolic Flow for Bosonic Many-body Models: Part 1 -
  Main Results and Algebra

abstract:
  This paper is a contribution to a program to see symmetry breaking in a
weakly interacting many Boson system on a three dimensional lattice at low
temperature. It is part of an analysis of the "small field" approximation to
the "parabolic flow" which exhibits the formation of a "Mexican hat" potential
well. Here we state the main result of this analysis, outline the strategy of
the proof, which uses a renormalization group flow, and perform the first,
algebraic, part of a renormalization group step.


title:
The Small Field Parabolic Flow for Bosonic Many-body Models: Part 2 -
  Fluctuation Integral and Renormalization

abstract:
  This paper is a contribution to a program to see symmetry breaking in a
weakly interacting many Boson system on a three dimensional lattice at low
temperature. It is part of an analysis of the "small field" approximation to
the "parabolic flow" which exhibits the formation of a "Mexican hat" potential
well. Here we complete the analysis of a renormalization group step by
"evaluating" the fluctuation integral and renormalizing the chemical potential.


title:
The Small Field Parabolic Flow for Bosonic Many-body Models: Part 3 -
  Nonperturbatively Small Errors

abstract:
  This paper is a contribution to a program to see symmetry breaking in a
weakly interacting many Boson system on a three dimensional lattice at low
temperature. It is part of an analysis of the "parabolic flow" which exhibits
the formation of a "Mexican hat" potential well. Here we provide arguments that
suggest, but do not completey prove, that the difference between the "small
field" approximation and the full model is nonperturbatively small.


title:
The Small Field Parabolic Flow for Bosonic Many-body Models: Part 4 -
  Background and Critical Field Estimates

abstract:
  This paper is a contribution to a program to see symmetry breaking in a
weakly interacting many Boson system on a three dimensional lattice at low
temperature. It is part of an analysis of the "small field" approximation to
the "parabolic flow" which exhibits the formation of a "Mexican hat" potential
well. Here we prove the existence of and bounds on the background and critical
fields that arise from the steepest descent attack that is at the core of our
renormalization group step anaylsis of these models.


title:
Short note on energy maximization property of the first eigenfunction of
  the Laplacian

abstract:
  We consider the Dirichlet-energy maximization problem of the solution $u_f$
of (\ref{main}), among all functions $f\in L^2(D)$, such that $\|f\|_2= 1$. We
show that the two maximizers are the first eigenfunctions of the Laplacian with
Dirichlet boundary condition $f=\pm u_1$.


title: Random functions from coupled dynamical systems

abstract:
  Let $f:T\longrightarrow T$ be a mapping and $\Omega$ be a subset of $T$ which
intersects every (positive) orbit of $f$. Assume that there are given a second
dynamical system $\lambda:Y\longrightarrow Y$ and a mapping
$\alpha:\Omega\longrightarrow Y$. For $t\in T$ let $\delta(t)$ be the smallest
$k$ such that $f^k(t)\in\Omega$ and let $t_\Omega:=f^{\delta(t)}(t)$ be the
first element in the orbit of $t$ which belongs to $\Omega$. Then we define a
mapping $F:T\longrightarrow Y$ by $F(t):=\lambda^{\delta(t)}(t_\Omega)$.


title:
Quantum fluctuation induced time of flight correlations of an
  interacting trapped Bose gas

abstract:
  We investigate numerically the momentum correlations in a two dimensional,
harmonically trapped interacting Bose system at $T=0$ temperature, by using a
particle number preserving Bogoliubov approximation. Interaction induced
quantum fluctuations of the quasi-condensate lead to a large anti-correlation
dip between particles of wave numbers $\mathbf{k}$ and $-\mathbf{k}$ for
$|\mathbf{k}|\sim 1/R_c$, with $R_c$ typical size of the condensate. The
anti-correlation dip found is a clear fingerprint of coherent quantum
fluctuations of the condensate. In contrast, for larger wave numbers,
$|\mathbf{k}| >> 1/R_c$, a weak positive correlation is found between particles
of wave numbers $\mathbf{k}$ and $-\mathbf{k}$, in accordance with the
Bogoliubov result for homogeneous interacting systems.


title:
Structure, ferromagnetic, dielectric and electronic features of the
  LaBiFe2O6 material

abstract:
  In this paper the synthesis and study of the structural, morphological,
electrical, magnetic and electronic properties of the LaBiFe2O6 novel material
are reported. The material was produced using the standard ceramic method. The
Rietveld analysis of experimental data of x-ray diffraction showed that it
synthesizes in an orthorhombic perovskite structure (Pnma, #62 space group).
Two types of grain, micro and submicrometric, with the LaBiFe2O6 stoichiometry
were identified by scanning electron microscopy and X-ray dispersive
spectroscopy. Results of electrical polarization and dielectric constant
ferroelectric suggest the occurrence of response of the material at room
temperature. A T=300 K the material is ferromagnetic and exhibits an anomaly at
T=258 K, which is attributed to anisotropy effects, suggesting the occurrence
of biferroic behaviour. Results of diffuse reflectance suggest a semiconductor
behaviour with energy gap Eg=2,17 eV, which is in agreement with calculations
of band structure and density of states for one spin orientation, while for the
other spin configuration calculations suggest a conductor feature.


title: Error correcting power of small topological codes

abstract:
  Many quantum technologies are now reaching a high level of maturity and
control, and it is likely that the first demonstrations of suppression of
naturally occurring quantum noise using small topological error correcting
codes will soon be possible. In doing this it will be necessary to define clear
achievable metrics to measure and compare the performance of real codes. Here
we consider the smallest examples of several families of topological codes:
surface codes, color codes, and the gauge color code, and determine the minimum
requirements to demonstrate error suppression. We use an exact decoder to
compare the performance of the codes under simple models of both physical error
and measurement error, and determine regions of correctability in the physical
parameters for each code.


title:
Sagging Ropes Demonstrate the Transversality Conditions of Variational
  Problems

abstract:
  An account of the transversality conditions of variational problems gives
rise to essential results in the analysis of different physical phenomena. This
powerful and elegant approach has proven to be fruitful in a diversity of
variational problems with free endpoints, when the endpoints are free to slip
along preset curves. We illustrate the transversality condition by the study of
a heavy inextensible rope sagging both symmetrically and asymmetrically between
two steering variously-shaped guide wires without friction. In this case, the
transversality conditions lead to the orthogonality of the rope to the wires at
endpoints of the rope, which is confirmed experimentally. Freeing the endpoints
of the rope yields exact and simple analytical equations predicting the tension
of the rope. Heavy ropes whose endpoints are free to slip between
variously-shaped wires are discussed.


title: Compact Layered Drawings of General Directed Graphs

abstract:
  We consider the problem of layering general directed graphs under height and
possibly also width constraints. Given a directed graph G = (V,A) and a maximal
height, we propose a layering approach that minimizes a weighted sum of the
number of reversed arcs, the arc lengths, and the width of the drawing. We call
this the Compact Generalized Layering Problem (CGLP). Here, the width of a
drawing is defined as the maximum sum of the number of vertices placed on a
layer and the number of dummy vertices caused by arcs traversing the layer. The
CGLP is NP-hard. We present two MIP models for this problem. The first one
(EXT) is our extension of a natural formulation for directed acyclic graphs as
suggested by Healy and Nikolov. The second one (CGL) is a new formulation based
on partial orderings. Our computational experiments on two benchmark sets show
that the CGL formulation can be solved much faster than EXT using standard
commercial MIP solvers. Moreover, we suggest a variant of CGL, called MML, that
can be seen as a heuristic approach. In our experiments, MML clearly improves
on CGL in terms of running time while it does not considerably increase the
average arc lengths and widths of the layouts although it solves a slightly
different problem where the dummy vertices are not taken into account.


title: Limit Shapes of the Stochastic Six Vertex Model

abstract:
  We show that limit shapes for the stochastic 6-vertex model on a cylinder
with the uniform boundary state on one end are solutions to the Burger type
equation. Solutions to these equations are studied for step initial conditions.
When the circumference of the cylinder goes to infinity the solution
corresponding to critical initial densities coincides with the one found by
Borodin, Corwin and Gorin.

categories: math-ph cond-mat.stat-mech math.MP math.PR


title: Interacting photon pulses in Rydberg medium

abstract:
  The understanding of dynamical evolutions of interacting photon pulses in
Rydberg atomic ensemble is the prerequisite for realizing quantum devices with
such system. We present an approach that efficiently simulates the dynamical
processes, using a set of local functions we construct to reflect the profiles
of narrowband pulses. For two counter-propagating photon pulses, our approach
predicts the distinct phenomena from the widely concerned Rydberg blockade to
the previously less noticed significant absorption in the anomalous dispersion
regime, which can occur by respectively setting the pulse frequency to the
appropriate values. Our numerical simulations also demonstrate how spatially
extending photon pulses become deformed under realistic non-uniform interaction
over their distributions.


title: Notes on non-singular models of black holes

abstract:
  We discuss static spherically symmetric metrics which represent non-singular
black holes in four- and higher-dimensional spacetime. We impose a set of
restrictions, such as a regularity of the metric at the center $r=0$ and
Schwarzschild asymptotic behavior at large $r$. We assume that the metric
besides mass $M$ contains an additional parameter $\ell$, which determines the
scale where modification of the solution of the Einstein equations becomes
significant. We require that the modified metric obeys the limiting curvature
condition, that is its curvature is uniformly restricted by the value $\sim
\ell^{-2}$. We also make a "more technical" assumption that the metric
coefficients are rational functions of $r$. In particular, the invariant
$(\nabla r)^2$ has the form $P_n(r)/\tilde{P}_n(r)$, where $P_n$ and
$\tilde{P}_n$ are polynomials of the order of $n$. We discuss first the case of
four dimensions. We show that when $n\le 2$ such a metric cannot describe a
non-singular black hole. For $n=3$ we find a suitable metric, which besides $M$
and $\ell$ contains a dimensionless numerical parameter. When this parameter
vanishes the obtained metric coincides with Hayward's one. The characteristic
property of such spacetimes is $-\xi^2=(\nabla r)^2$, where $\xi^2$ is a
time-like at infinity Killing vector. We describe a possible generalization of
a non-singular black-hole metric to the case when this equality is violated. We
also obtain a metric for a charged non-singular black hole obeying similar
restrictions as the neutral one, and construct higher dimensional models of
neutral and charged black holes.


title: Tuning for Software Analytics: is it Really Necessary?

abstract:
  Context: Data miners have been widely used in software engineering to, say,
generate defect predictors from static code measures. Such static code defect
predictors perform well compared to manual methods, and they are easy to use
and useful to use. But one of the "black art" of data mining is setting the
tunings that control the miner. Objective:We seek simple, automatic, and very
effective method for finding those tunings. Method: For each experiment with
different data sets (from open source JAVA systems), we ran differential
evolution as anoptimizer to explore the tuning space (as a first step) then
tested the tunings using hold-out data. Results: Contrary to our prior
expectations, we found these tunings were remarkably simple: it only required
tens, not thousands,of attempts to obtain very good results. For example, when
learning software defect predictors, this method can quickly find tuningsthat
alter detection precision from 0% to 60%. Conclusion: Since (1) the
improvements are so large, and (2) the tuning is so simple, we need to change
standard methods insoftware analytics. At least for defect prediction, it is no
longer enough to just run a data miner and present the resultwithoutconducting
a tuning optimization study. The implication for other kinds of analytics is
now an open and pressing issue


title: Breather soliton dynamics in microresonators

abstract:
  The generation of temporal cavity solitons in microresonators results in
low-noise optical frequency combs which are critical for applications in
spectroscopy, astronomy, navigation or telecommunications. Breather solitons
also form an important part of many different classes of nonlinear wave systems
with a localized temporal structure that exhibits oscillatory behavior. To
date, the dynamics of breather solitons in microresonators remains largely
unexplored, and its experimental characterization is challenging. Here, we
demonstrate the excitation of breather solitons in two different microresonator
platforms based on silicon nitride and on silicon. We investigate the
dependence of the breathing frequency on pump detuning and observe the
transition from period-1 to period-2 oscillation in good agreement with the
numerical simulations. Our study presents experimental confirmation of the
stability diagram of dissipative cavity solitons predicted by the
Lugiato-Lefever equation and is importance to understanding the fundamental
dynamical properties of solitons within the larger context of nonlinear
science.


title: Fundamental limitations for antenna radiation efficiency

abstract:
  Small volume, finite conductivity and high frequencies are major imperatives
in the design of communications infrastructure. The radiation efficiency
$\eta_r$ impacts on the optimal gain, quality factor, and bandwidth. The
current efficiency limit applies to structures confined to a radian sphere $ka$
($k$ is the wave number, $a$ is the radius). Here we present new absolute
limits to $\eta_r$ for arbitrary antenna shapes based on $k^2S$ where $S$ is
the conductor surface area. For a dipole with an electrical length of $10^{-5}$
our result is four orders of magnitude closer to the analytical solution when
compared with previous bounds on the efficiency. The improved bound on $\eta_r$
is more accurate, more general, and easier to calculate than other limits. The
efficiency of an antenna cannot be larger than the case where the surface of
the antenna is 'peeled' off and assembled into a planar sheet with area $S$,
and a uniform current is excited along the surface of this sheet.


title: Shining Light on Polarizable Dark Particles

abstract:
  We investigate the possibilities of searching for a self-conjugate
polarizable particle in the self-interactions of light. We first observe that
polarizability can arise either from the exchange of mediator states or as a
consequence of the inner structure of the particle. To exemplify this second
possibility we calculate the polarizability of a neutral bosonic open string,
and find it is described only by dimension-8 operators. Focussing on the spin-0
case, we calculate the light-by-light scattering amplitudes induced by the
dimension-6 and 8 polarizability operators. Performing a simulation of
exclusive diphoton production with proton tagging at the LHC, we find that the
imprint of the polarizable dark particle can be potentially detected at
5$\sigma$ significance for mass and cutoff reaching values above the TeV scale,
for $\sqrt{s}=$13~TeV and 300 fb$^{-1}$ of integrated luminosity. If the
polarizable dark particle is stable, it can be a dark matter candidate, in
which case we argue this exclusive diphoton search may complement the existing
LHC searches for polarizable dark matter.


title: Hausdorff dimension of boundaries of relatively hyperbolic groups

abstract:
  In this paper, we study the Hausdorff dimension of the Floyd and Bowditch
boundaries of a relatively hyperbolic group, and show that for the Floyd metric
and shortcut metrics respectively, they are are both equal to a constant times
the growth rate of the group.
  In the proof, we study a special class of conical points called uniformly
conical points and establish that, in both boundaries, there exists a sequence
of Alhfors regular sets with dimension tending to the Hausdorff dimension and
these sets consist of uniformly conical points.


title:
Crawling and turning in a minimal reaction-diffusion cell motility
  model: coupling cell shape and biochemistry

abstract:
  We study a minimal model of a crawling eukaryotic cell with a chemical
polarity controlled by a reaction-diffusion mechanism describing Rho GTPase
dynamics. The size, shape, and speed of the cell emerge from the combination of
the chemical polarity, which controls the locations where actin polymerization
occurs, and the physical properties of the cell, including its membrane
tension. We find in our model both highly persistent trajectories, in which the
cell crawls in a straight line, and turning trajectories, where the cell
transitions from crawling in a line to crawling in a circle. We discuss the
controlling variables for this turning instability, and argue that turning
arises from a coupling between the reaction-diffusion mechanism and the shape
of the cell. This emphasizes the surprising features that can arise from simple
links between cell mechanics and biochemistry. Our results suggest that similar
instabilities may be present in a broad class of biochemical descriptions of
cell polarity.


title: The Mid-Infrared Evolution of the FU Orionis Disk

abstract:
  We present new SOFIA-FORCAST observations obtained in Feburary 2016 of the
archetypal outbursting low mass young stellar object FU Orionis, and compare
the continuum, solid state, and gas properties with mid-IR data obtained at the
same wavelengths in 2004 with Spitzer-IRS. In this study, we conduct the first
mid-IR spectroscopic comparison of an FUor over a long time period. Over a 12
year period, UBVR monitoring indicates that FU Orionis has continued its steady
decrease in overall brightness by ~ 14%. We find that this decrease in
luminosity occurs only at wavelengths < 20 microns. In particular, the
continuum short ward of the silicate emission complex at 10 microns exhibits a
~ 12% (~ 3 sigma) drop in flux density, but no apparent change in slope; both
the Spitzer and SOFIA spectra are consistent with a 7200 K blackbody.
Additionally, the detection of water absorption is consistent with the Spitzer
spectrum. The silicate emission feature at 10 microns continues to be
consistent with unprocessed grains, unchanged over 12 years. We conclude that
either the accretion rate in FU Orionis has decreased by ~ 12-14% over this
time baseline, or that the inner disk has cooled, but the accretion disk
remains in a superheated state outside of the innermost region.


title: Multiparameter quantum Schur duality of type B

abstract:
  We establish a Schur type duality between a coideal subalgebra of the quantum
group of type A and the Hecke algebra of type B with 2 parameters. We identify
the $\imath$-canonical basis on the tensor product of the natural
representation with Lusztig's canonical basis of the type B Hecke algebra with
unequal parameters associated to a weight function.


title:
Impact of finite temperatures on the transport properties of Gd from
  first principles

abstract:
  Finite temperature effects have a pronounced impact on the transport
properties of solids. In magnetic systems, besides the scattering of conduction
electrons by impurities and phonons, an additional scattering source coming
from the magnetic degrees of freedom must be taken into account. A
first-principle scheme which treats all these scattering effects on equal
footing was recently suggested within the framework of the multiple scattering
formalism. Employing the alloy analogy model treated by means of the CPA,
thermal lattice vibrations and spin fluctuations are effectively taken into
account. In the present work the temperature dependence of the longitudinal
resistivity and the anomalous Hall effect in the strongly correlated metal Gd
is considered. The comparison with experiments demonstrates that the proposed
numerical scheme does provide an adequate description of the electronic
transport at finite temperatures.


title: First year results of the High Altitude Water Cherenkov observatory

abstract:
  The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide
field of view (1.8 Sr) and high duty cycle (>95% up-time) detector of unique
capabilities for the study of TeV gamma-ray sources. Installed at an altitude
of 4100m in the Northern slope of Volc\'an Sierra Negra, Puebla, by a
collaboration of about thirty institutions of Mexico and the United States,
HAWC has been in full operations since March 2015, surveying 2/3 of the sky
every sidereal day, monitoring active galaxies and mapping sources in the
Galactic Plane to a detection level of 1 Crab per day. This contribution
summarizes the main results of the first year of observations of the HAWC
gamma-ray observatory.


title: Spinon and bound state excitation "light cones" in Heisenberg XXZ Chains

abstract:
  We investigate the out-of-equilibrium dynamics after a local quench that
connects two spin-1/2 XXZ chains prepared in the ground state of the
Hamiltonian in different phases, one in the ferromagnetic phase and the other
in the critical phase. We analyze the time evolution of the on-site
magnetization and bipartite entanglement entropy via adaptive time-dependent
density matrix renormalization group. In systems with short-range inter-
actions, such as the one we consider, the velocity of information transfer is
expected to be bounded, giving rise to a light-cone effect. Interestingly, our
results show that, when the anisotropy parameter of the critical chain is
sufficiently close to that of the isotropic ferromagnet, the light cone is
determined by the velocity of spin-wave bound states that propagate faster than
single-particle ("spinon") excitations. Furthermore, we investigate how the
system approaches equilibrium in the inhomogeneous ground state of the
connected system, in which the ferromagnetic chain induces a nonzero
magnetization in the critical chain in the vicinity of the interface.


title:
Light dark matter in neutrino beams: production modelling and scattering
  signatures at MiniBooNE, T2K and SHiP

abstract:
  We analyze the prospects for detection of light sub-GeV dark matter produced
in experiments designed to study the properties of neutrinos, such as
MiniBooNE, T2K, SHiP, DUNE etc. We present an improved production model, when
dark matter couples to hadronic states via a dark photon or baryonic vector
mediator, incorporating bremsstrahlung of the dark vector. In addition to
elastic scattering, we also study signatures of light dark matter undergoing
deep inelastic or quasi-elastic NC$\pi^0$-like scattering in the detector
producing neutral pions, which for certain experiments may provide the best
sensitivity.
  An extensive appendix provides documentation for a publicly available
simulation tool {\tt BdNMC} that can be applied to determine the hidden sector
dark matter production and scattering rate at a range of proton fixed target
experiments.


title: Ring theoretical properties of affine cellular algebras

abstract:
  As a generalisation of Graham and Lehrer's cellular algebras, affine cellular
algebras have been introduced in [12] in order to treat affine versions of
diagram algebras like affine Hecke algebras of type A and affine Temperley-Lieb
algebras in a unifying fashion. Affine cellular algebras include Kleshchev's
graded quasihereditary algebras, KLR algebras and various other classes of
algebras. In this paper we will study ring theoretical properties of affine
cellular algebras. We show that any affine cellular algebra $A$ satisfies a
polynomial identity. Furthermore, we show that $A$ can be embedded into its
asymptotic algebra if the occurring commutative affine algebra $B_j$ are
reduced and the determinants of the swich matrices are non-zero divisors. As a
consequence, we show that the Gelfand-Kirillov dimension of $A$ is less than or
equal to the largest Krull dimension of the algebras $B_j$ and that equality
hold, in case all affine cell ideals are idempotent or if the Krull dimension
of the algebras $B_j$ is less than or equal to $1$. Special emphasis is given
to the question when an affine cell ideal is idempotent, generated by an
idempotent or finitely generated.


title: Quantal Nucleon Diffusion I: Central Collisions of Symmetric Nuclei

abstract:
  Quantal diffusion mechanism of nucleon exchange is studied in the central
collisions of several symmetric heavy-ion collisions in the framework of the
Stochastic Mean-Field (SMF) approach. Since at bombarding energies below the
fusion barrier, di-nuclear structure is maintained, it is possible to describe
nucleon exchange as a diffusion process familiar from deep-inelastic
collisions. Quantal diffusion coefficients, including memory effects, for
proton and neutron exchanges are extracted microscopically employing the SMF
approach. The quantal calculations of neutron and proton variances are compared
with the semi-classical results.


title:
An analogue of the Kostant-Rallis multiplicity theorem for
  $\theta$-group harmonics

abstract:
  The main result in this paper is the generalization of the Kostant-Rallis
multiplicity formula to general {\theta}--groups (in the sense of Vinberg). The
special cases of the two most interesting examples one for $E_6$ (three qubits)
and one for $E_8$ are given explicit formulas.


title:
A Note on "How Robust Standard Errors Expose Methodological Problems
  They Do Not Fix, and What to Do About It"

abstract:
  King and Roberts (2015, KR) claim that a disagreement between robust and
classical standard errors exposes model misspecification. We emphasize that
KR's claim only generally applies to parametric models: models that assume a
restrictive form of the distribution of the outcome. Many common models in use
in political science, including the linear model, are not necessarily
parametric -- rather they may be semiparametric. Common estimators of model
parameters such as ordinary least squares have both robust (corresponding to a
semiparametric model) and classical (corresponding to a more restrictive model)
standard error estimates. Given a properly specified semiparametric model and
mild regularity conditions, the classical standard errors are not generally
consistent, but the robust standard errors are. To illustrate this point, we
consider the case of the regression estimate of a semiparametric linear model
with no model misspecification, and show that robust standard errors may
nevertheless systematically differ from classical standard errors. We show that
a disagreement between robust and classical standard errors is not generally
suitable as a diagnostic for regression estimators, and that KR's reanalyses of
Neumayer (2003) and B\"uthe and Milner (2008) are predicated on strong
assumptions that the original authors did not invoke nor require.


title:
Performance Measures and a Data Set for Multi-Target, Multi-Camera
  Tracking

abstract:
  To help accelerate progress in multi-target, multi-camera tracking systems,
we present (i) a new pair of precision-recall measures of performance that
treats errors of all types uniformly and emphasizes correct identification over
sources of error; (ii) the largest fully-annotated and calibrated data set to
date with more than 2 million frames of 1080p, 60fps video taken by 8 cameras
observing more than 2,700 identities over 85 minutes; and (iii) a reference
software system as a comparison baseline. We show that (i) our measures
properly account for bottom-line identity match performance in the multi-camera
setting; (ii) our data set poses realistic challenges to current trackers; and
(iii) the performance of our system is comparable to the state of the art.


title:
Thermal Transport Across Metal Silicide-Silicon Interfaces: An
  Experimental Comparison between Epitaxial and Non-epitaxial Interfaces

abstract:
  Silicides are used extensively in nano- and microdevices due to their low
electrical resistivity, low contact resistance to silicon, and their process
compatibility. In this work, the thermal interface conductance of TiSi$_2$,
CoSi$_2$, NiSi and PtSi are studied using time-domain thermoreflectance.
Exploiting the fact that most silicides formed on Si(111) substrates grow
epitaxially, while most silicides on Si(100) do not, we study the effect of
epitaxy, and show that for a wide variety of interfaces there is no difference
in the thermal interface conductance of epitaxial and non-epitaxial
silicide/silicon interfaces. The effect of substrate carrier concentration is
also investigated over a wide range of p- and n-type doping, and is found to be
independent of carrier concentration, regardless of whether the interface is
epitaxial and regardless of silicide type. In the case of epitaxial CoSi$_2$, a
comparison of temperature dependant experimental data is made with two detailed
computational models using (1) full-dispersion diffuse mismatch modeling (DMM)
including the effect of near-interfacial strain and (2) an atomistic Green'
function (AGF) approach that integrates near-interface changes in the
interatomic force constants obtained through density functional perturbation
theory. At temperatures above 100K, the AGF approach greatly underpredicts the
CoSi$_2$ data, while the DMM prediction matches the data well. The
full-dispersion DMM is also found to closely predict the experimentally
observed temperature-dependent interface conductance for epitaxial NiSi/Si and
non-epitaxial TiSi$_2$/Si interfaces. In the case of epitaxial PtSi/Si
interfaces, full dispersion DMM significantly overpredicts the experimental
data.


title:
Band gap renormalization and work function tuning in MoSe2/hBN/Ru(0001)
  heterostructures

abstract:
  Here we report the successful growth of MoSe2 on single layer hexagonal boron
nitride (hBN) on Ru(0001) substrate by using molecular beam epitaxy. We
investigated the electronic structures of MoSe2 using scanning tunneling
microscopy and spectroscopy. Surprisingly, we found that the quasi-particle gap
of the MoSe2 on hBN/Ru is about 0.25 eV smaller than those on graphene or
graphite substrates. We attribute this result to the strong interaction between
hBN/Ru which causes residual metallic screening from the substrate. The surface
of MoSe2 exhibits Moir\'e pattern that replicates the Moir\'e pattern of
hBN/Ru. In addition, the electronic structure and the work function of MoSe2
are modulated electrostatically with an amplitude of ~ 0.13 eV. Most
interestingly, this electrostatic modulation is spatially in phase with the
Moir\'e pattern of hBN on Ru(0001) whose surface also exhibits a work function
modulation of the same amplitude.


title: Mobile Communication Signatures of Unemployment

abstract:
  The mapping of populations socio-economic well-being is highly constrained by
the logistics of censuses and surveys. Consequently, spatially detailed changes
across scales of days, weeks, or months, or even year to year, are difficult to
assess; thus the speed of which policies can be designed and evaluated is
limited. However, recent studies have shown the value of mobile phone data as
an enabling methodology for demographic modeling and measurement. In this work,
we investigate whether indicators extracted from mobile phone usage can reveal
information about the socio-economical status of microregions such as districts
(i.e., average spatial resolution < 2.7km). For this we examine anonymized
mobile phone metadata combined with beneficiaries records from unemployment
benefit program. We find that aggregated activity, social, and mobility
patterns strongly correlate with unemployment. Furthermore, we construct a
simple model to produce accurate reconstruction of district level unemployment
from their mobile communication patterns alone. Our results suggest that
reliable and cost-effective economical indicators could be built based on
passively collected and anonymized mobile phone data. With similar data being
collected every day by telecommunication services across the world,
survey-based methods of measuring community socioeconomic status could
potentially be augmented or replaced by such passive sensing methods in the
future.


title:
A high resolution HI study towards the supernova remnant Puppis A and
  its environments

abstract:
  We observed the supernova remnant (SNR) Puppis A in the 21 cm line with the
Australia Telescope Compact Array with the aim of determining the systemic
velocity and, hence, the corresponding kinematic distance. For the compact,
background sources in the field, we obtain absorption spectra by applying two
methods: (a) subtracting profiles on- and off-source towards continuum
emission, and (b) filtering short spacial frequencies in the Fourier plane to
remove large scale emission. One of the brightest features to the East of the
shell of Puppis A was found to be a background source, probably extragalactic.
Removing the contribution from this and the previously known unrelated sources,
the systemic velocity of Puppis A turns out to be limited between 8 and 12 km
s$^{-1}$, which places this source at a distance of 1.3 $\pm$ 0.3 kpc. From the
combined images that include both single dish and interferometric data, we
analyze the distribution of the interstellar hydrogen. We suggest that an
ellipsoidal ring at $v \sim $+8 km s$^{-1}$ could be the relic of a bubble
blown by the progenitor of Puppis A, provided the distance is $\lesssim$ 1.2
kpc. The main consequences of the new systemic velocity and distance as
compared with previous publications ($v =$ +16 km s$^{-1}$ and $d = $2.2 kpc)
are the absence of a dense interacting cloud to the East to explain the
morphology, and the decrease of the shell size and the neutron star velocity,
which are now in better agreement with statistical values.