title: Enantiomer-Specific State Transfer of Chiral Molecules

abstract:
  State-selective enantiomeric excess is realized using microwave-driven
coherent population transfer. The method selectively promotes either R or S
molecules to a higher rotational state by phase-controlled microwave pulses
that drive electric-dipole allowed rotational transitions. We demonstrate the
enantiomer-specific state transfer method using enantiopure samples of
1,2-propanediol. This method of state-specific enantiomeric enrichment can be
applied to a large class of asymmetric, chiral molecules that can be vaporized
and cooled to the point where rotationally resolved spectroscopy is possible,
including molecules that rapidly racemize. The rapid chiral switching
demonstrated here allows for new approaches in high-precision spectroscopic
searches for parity violation in chiral molecules.


title: General Theory of the Plasmoid Instability

abstract:
  A general theory of the onset and development of the plasmoid instability is
formulated by means of a principle of least time. The scaling relations for the
final aspect ratio, transition time to rapid onset, growth rate, and number of
plasmoids are derived, and shown to depend on the initial perturbation
amplitude $\left({\hat w}_0\right)$, the characteristic rate of current sheet
evolution $\left(1/\tau\right)$, and the Lundquist number $\left(S\right)$.
They are not simple power laws, and are proportional to $S^{\alpha}
\tau^{\beta} \left[\ln f(S,\tau,{\hat w}_0)\right]^\sigma$. The detailed
dynamics of the instability is also elucidated, and shown to comprise of a
period of quiescence followed by sudden growth over a short time scale.

categories: physics.plasm-ph astro-ph.HE astro-ph.SR math-ph math.MP


title:
Momentum-resolved observation of thermal and quantum depletion in an
  interacting Bose gas

abstract:
  We report on the single-atom-resolved measurement of the distribution of
momenta $\hbar k$ in a weakly interacting Bose gas after a 330 ms
time-of-flight. We investigate it for various temperatures and clearly separate
two contributions to the depletion of the condensate by their $k$-dependence.
The first one is the thermal depletion. The second contribution falls of as
$k^{-4}$, and its magnitude increases with the in-trap condensate density as
predicted by the Bogoliubov theory at zero temperature. These observations
suggest associating it with the quantum depletion. How this contribution can
survive the expansion of the released interacting condensate is an intriguing
open question.


title: Accelerating scientific codes by performance and accuracy modeling

abstract:
  Scientific software is often driven by multiple parameters that affect both
accuracy and performance. Since finding the optimal configuration of these
parameters is a highly complex task, it extremely common that the software is
used suboptimally. In a typical scenario, accuracy requirements are imposed,
and attained through suboptimal performance. In this paper, we present a
methodology for the automatic selection of parameters for simulation codes, and
a corresponding prototype tool. To be amenable to our methodology, the target
code must expose the parameters affecting accuracy and performance, and there
must be formulas available for error bounds and computational complexity of the
underlying methods. As a case study, we consider the particle-particle
particle-mesh method (PPPM) from the LAMMPS suite for molecular dynamics, and
use our tool to identify configurations of the input parameters that achieve a
given accuracy in the shortest execution time. When compared with the
configurations suggested by expert users, the parameters selected by our tool
yield reductions in the time-to-solution ranging between 10% and 60%. In other
words, for the typical scenario where a fixed number of core-hours are granted
and simulations of a fixed number of timesteps are to be run, usage of our tool
may allow up to twice as many simulations. While we develop our ideas using
LAMMPS as computational framework and use the PPPM method for dispersion as
case study, the methodology is general and valid for a range of software tools
and methods.


title: Parameterized Principal Component Analysis

abstract:
  When modeling multivariate data, one might have an extra parameter of
contextual information that could be used to treat some observations as more
similar to others. For example, images of faces can vary by age, and one would
expect the face of a 40 year old to be more similar to the face of a 30 year
old than to a baby face. We introduce a novel manifold approximation method,
parameterized principal component analysis (PPCA) that models data with linear
subspaces that change continuously according to the extra parameter of
contextual information (e.g. age), instead of ad-hoc atlases. Special care has
been taken in the loss function and the optimization method to encourage
smoothly changing subspaces across the parameter values. The approach ensures
that each observation's projection will share information with observations
that have similar parameter values, but not with observations that have large
parameter differences. We tested PPCA on artificial data based on known, smooth
functions of an added parameter, as well as on three real datasets with
different types of parameters. We compared PPCA to PCA, sparse PCA and to
independent principal component analysis (IPCA), which groups observations by
their parameter values and projects each group using PCA with no sharing of
information for different groups. PPCA recovers the known functions with less
error and projects the datasets' test set observations with consistently less
reconstruction error than IPCA does. In some cases where the manifold is truly
nonlinear, PCA outperforms all the other manifold approximation methods
compared.


title: Compactly-supported Wannier functions and algebraic $K$-theory

abstract:
  In a tight-binding lattice model with $n$ orbitals (single-particle states)
per site, Wannier functions are $n$-component vector functions of position that
fall off rapidly away from some location, and such that a set of them in some
sense span all states in a given energy band or set of bands;
compactly-supported Wannier functions are such functions that vanish outside a
bounded region. They arise not only in band theory, but also in connection with
tensor-network states for non-interacting fermion systems, and for flat-band
Hamiltonians with strictly short-range hopping matrix elements. In earlier
work, it was proved that for general complex band structures (vector bundles)
or general complex Hamiltonians---that is, class A in the ten-fold
classification of Hamiltonians and band structures---a set of
compactly-supported Wannier functions can span the vector bundle only if the
bundle is topologically trivial, in any dimension $d$ of space, even when use
of an overcomplete set of such functions is permitted. This implied that, for a
free-fermion tensor network state with a non-trivial bundle in class A, any
strictly short-range parent Hamiltonian must be gapless. Here, this result is
extended to all ten symmetry classes of band structures without additional
crystallographic symmetries, with the result that in general the non-trivial
bundles that can arise from compactly-supported Wannier-type functions are
those that may possess, in each of $d$ directions, the non-trivial winding that
can occur in the same symmetry class in one dimension, but nothing else. The
results are obtained from a very natural usage of algebraic $K$-theory, based
on a ring of polynomials in $e^{\pm ik_x}$, $e^{\pm ik_y}$, . . . , which occur
as entries in the Fourier-transformed Wannier functions.

categories: cond-mat.mes-hall cond-mat.mtrl-sci math-ph math.MP quant-ph


title: On the identification of random variables from quantized observations

abstract:
  We prove that the scale and shift parameters of a family of probability laws
can be identified from quantized values, under appropriate assumptions. As an
application, we show the consistency of the maximum likelihood estimator for
the parameters of a quantized Gaussian autoregressive process.


title: Evaluating Causal Models by Comparing Interventional Distributions

abstract:
  The predominant method for evaluating the quality of causal models is to
measure the graphical accuracy of the learned model structure. We present an
alternative method for evaluating causal models that directly measures the
accuracy of estimated interventional distributions. We contrast such
distributional measures with structural measures, such as structural Hamming
distance and structural intervention distance, showing that structural measures
often correspond poorly to the accuracy of estimated interventional
distributions. We use a number of real and synthetic datasets to illustrate
various scenarios in which structural measures provide misleading results with
respect to algorithm selection and parameter tuning, and we recommend that
distributional measures become the new standard for evaluating causal models.


title:
Corrections to nucleon capture cross sections computed in truncated
  Hilbert spaces

abstract:
  Nucleon capture cross sections enter various astrophysical processes. The
measurement of proton capture on nuclei at astrophysically relevant low
energies is a challenge, and theoretical computations in this long-wavelength
regime are sensitive to the long-distance asymptotics of the wave functions. A
theoretical foundation for estimating and correcting errors introduced in
capture cross sections due to Hilbert space truncation has so far been lacking.
We derive extrapolation formulas that relate the infrared regularized capture
amplitudes to the infinite basis limit and demonstrate their efficacy for
proton-proton fusion. Our results are thus relevant to current calculations of
few-body capture reactions such as proton-proton fusion or proton capture on
the deuteron, and they also open the way for the use of {\it ab initio}
many-body wave functions represented in finite Hilbert spaces in precision
calculations of nucleon capture on heavier nuclei.


title:
A Data-Driven Approach to Estimating the Number of Clusters in
  Hierarchical Clustering

abstract:
  We propose two new methods for estimating the number of clusters in a
hierarchical clustering framework in the hopes of creating a fully automated
process with no human intervention. The methods are completely data-driven and
require no input from the researcher, and as such are fully automated. They are
quite easy to implement and not computationally intensive in the least. We
analyze performance on several simulated data sets and the Biobase Gene
Expression Set, comparing our methods to the established Gap statistic and
Elbow methods and outperforming both in multi-cluster scenarios.


title: Polarization dOTF: on-sky focal plane wavefront sensing

abstract:
  The differential Optical Transfer Function (dOTF) is a focal plane wavefront
sensing method that uses a diversity in the pupil plane to generate two
different focal plane images. The difference of their Fourier transforms
recovers the complex amplitude of the pupil down to the spatial scale of the
diversity. We produce two simultaneous PSF images with diversity using a
polarizing filter at the edge of the telescope pupil, and a polarization camera
to simultaneously record the two images. Here we present the first on-sky
demonstration of polarization dOTF at the 1.0m South African Astronomical
Observatory telescope in Sutherland, and our attempt to validate it with
simultaneous Shack-Hartmann wavefront sensor images.


title: Complex orientations for THH of some perfectoid fields

abstract:
  This sketch argues that work of Hesselholt on the topological Hochschild
homology of $\Cp$ extends, using work of Scholze and others, to define complex
orientations for a version of topological Hochschild homology for rings of
integers in a natural class of generalized cyclotomic perfectoid fields; and
that the resulting spectra provide geometrically interesting targets for
analogs of the Chern character, defined for certain integral lifts of the
extraordinary $K$-functors of chromatic homotopy theory.


title:
A Density Functional study of Covalency in the Trihalides of Lutetium
  and Lawrencium

abstract:
  In this work we present a four component relativistic theoretical
investigation of the trihalides of lutetium and lawrencium, LuX3, LrX3 (X= F,
Cl, Br, I) respectively using density functional theory (DFT) with different
density functional and a geometrical optimisation procedure as implemented in
DIRAC-package. The results show the trend of bonding from lighter to the
heavier halide atoms and between 4f/5f atoms Lu and Lr.


title: Enumeration of Regular Maps on Surfaces of a Given Genus

abstract:
  In the present work the rooted and unrooted d-regular maps on 2-dimentional
oriented surfaces of genus g are enumerated. Separately and in more detail the
case of d-regular maps with a single face are considered.


title: On Strategic Multi-Antenna Jamming in Centralized Detection Networks

abstract:
  In this paper, we model a complete-information zero-sum game between a
centralized detection network with a multiple access channel (MAC) between the
sensors and the fusion center (FC), and a jammer with multiple transmitting
antennas. We choose error probability at the FC as the performance metric, and
investigate pure strategy equilibria for this game, and show that the jammer
has no impact on the FC's error probability by employing pure strategies at the
Nash equilibrium. Furthermore, we also show that the jammer has an impact on
the expected utility if it employs mixed strategies.


title: Rationally connected varieties - on a conjecture of Mumford

abstract:
  We establish a conjecture of Mumford characterizing rationally connected
complex projective manifolds in several cases.


title: Dirac's monopole, quaternions, and the Zassenhaus formula

abstract:
  Starting from the quaternionic quantization scheme proposed by Emch and
Jadczyk for describing the motion of a quantum particle in the magnetic
monopole field, we derive an algorithm for finding the differential
representation of the star product generated by the quaternionic Weyl
correspondence on phase-space functions. This procedure is illustrated by the
explicit calculation of the star product up to the second order in the Planck
constant. Our main tools are an operator analog of the twisted convolution and
the Zassenhaus formula for the products of exponentials of noncommuting
operators.


title:
On local combinatorial formulas for Chern classes of triangulated circle
  bundle

abstract:
  Principal circle bundle over a PL polyhedron can be triangulated and thus
obtains combinatorics. The triangulation is assembled from triangulated circle
bundles over simplices. To every triangulated circle bundle over a simplex we
associate a necklace (in combinatorial sense). We express rational local
formulas for all powers of first Chern class in the terms of mathematical
expectations of parities of the associated necklaces. This rational parity is a
combinatorial isomorphism invariant of triangulated circle bundle over simplex,
measuring mixing by triangulation of the circular graphs over vertices of the
simplex. The goal of this note is to sketch the logic of deduction these
formulas from Kontsevitch's cyclic invariant connection form on metric
polygons.


title:
On the role of the rotations and Bogoliubov transformations in neutrino
  mixing

abstract:
  We show that mixing transformations for Dirac fields arise as a consequence
of the non-trivial interplay between rotations and Bogoliubov transformations
at level of ladder operators. Indeed the non-commutativity between the
algebraic generators of such transformations turns out to be responsible of the
unitary inequivalence of the flavor and mass representations and of the
associated vacuum structure. A possible thermodynamic interpretation is also
investigated.


title:
Beyond mean-field dynamics of ultra-cold bosonic atoms in higher
  dimensions: facing the challenges with a multi-configurational approach

abstract:
  Exploring the impact of dimensionality on the quantum dynamics of interacting
bosons in traps including particle correlations is an interesting but
challenging task. Due to the different participating length scales the
modelling of the short-range interactions in three dimensions plays a special
role. We review different approaches for the latter and elaborate that for
multi-configurational computational strategies finite range potentials are
adequate resulting in the need of large grids to resolve the relevant length
scales. This results in computational challenges which include also the
exponential scaling of complexity with the number of atoms. We show that the
recently developed ab-initio Multi-Layer Multi-Configurational Time- Dependent
Hartee method for Bosons (ML-MCTDHB) [J. Chem. Phys. 139, 134103 (2013)] can
face both numerical challenges and present an efficient numerical
implementation of ML-MCTDHB in three spatial dimensions, particularly suited to
describe the quantum dynamics for elongated traps.
  The beneficial scaling of our approach is demonstrated by studying the
tunnelling dynamics of bosonic ensembles in a double well. Comparing
three-dimensional with quasi-one dimensional simulations, we find
dimensionality-induced effects in the density. Furthermore, we study the
crossover from weak transversal confinement, where a mean-field description of
the system is sufficient, towards tight transversal confinement, where particle
correlations and beyond mean-field effects are pronounced.


title: Quantum centipedes with strong global constraint

abstract:
  A centipede made of $N$ quantum walkers on a one-dimensional lattice is
considered. The distance between two consecutive legs is either one or two
lattice spacings, and a global constraint is imposed: the maximal distance
between the first and last leg is $N+1$. This is the strongest global
constraint compatible with walking. For an initial value of the wave function
corresponding to a localized configuration at the origin, the probability law
of the first leg of the centipede can be expressed in closed form in terms of
Bessel functions. The dispersion relation and the group velocities are worked
out exactly. Their maximal group velocity goes to zero when $N$ goes to
infinity, which is in contrast with the behaviour of group velocities of
quantum centipedes without global constraint, which were recently shown by
Krapivsky, Luck and Mallick to give rise to ballistic spreading of extremal
wave-front at non-zero velocity in the large-$N$ limit. The corresponding
Hamiltonians are implemented numerically, based on a block structure of the
space of configurations corresponding to compositions of the integer $N$. The
growth of the maximal group velocity when the strong constraint is gradually
relaxed is explored, and observed to be linear in the density of gaps allowed
in the configurations. Heuristic arguments are presented to infer that the
large-$N$ limit of the globally constrained model can yield finite group
velocities provided the allowed number of gaps is a finite fraction of $N$.


title: SMAP: Simultaneous Mapping and Planning on Occupancy Grids

abstract:
  Occupancy grids are the most common framework when it comes to creating a map
of the environment using a robot. This paper studies occupancy grids from the
motion planning perspective and proposes a mapping method that provides richer
data (map) for the purpose of planning and collision avoidance. Typically, in
occupancy grid mapping, each cell contains a single number representing the
probability of cell being occupied. This leads to conflicts in the map, and
more importantly inconsistency between the map error and reported confidence
values. Such inconsistencies pose challenges for the planner that relies on the
generated map for planning motions. In this work, we store a richer data at
each voxel including an accurate estimate of the variance of occupancy. We show
that in addition to achieving maps that are often more accurate than tradition
methods, the proposed filtering scheme demonstrates a much higher level of
consistency between its error and its reported confidence. This allows the
planner to reason about acquisition of the future sensory information. Such
planning can lead to active perception maneuvers that while guiding the robot
toward the goal aims at increasing the confidence in parts of the map that are
relevant to accomplishing the task.


title: Thermal Effects in Dense Matter Beyond Mean Field Theory

abstract:
  The formalism of next-to-leading order Fermi Liquid Theory is employed to
calculate the thermal properties of symmetric nuclear and pure neutron matter
in a relativistic many-body theory beyond the mean field level which includes
two-loop effects. For all thermal variables, the semi-analytical
next-to-leading order corrections reproduce results of the exact numerical
calculations for entropies per baryon up to 2. This corresponds to excellent
agreement down to sub-nuclear densities for temperatures up to $20$ MeV. In
addition to providing physical insights, a rapid evaluation of the equation of
state in the homogeneous phase of hot and dense matter is achieved through the
use of the zero-temperature Landau effective mass function and its derivatives.


title:
KELT-12b: A $P \sim 5$ Day, Highly Inflated Hot Jupiter Transiting a
  Mildly Evolved Hot Star

abstract:
  We report the discovery of KELT-12b, a highly inflated Jupiter-mass planet
transiting a mildly evolved host star. We identified the initial transit signal
in the KELT-North survey data and established the planetary nature of the
companion through precise follow-up photometry, high-resolution spectroscopy,
precise radial velocity measurements, and high-resolution adaptive optics
imaging. Our preferred best-fit model indicates that the $V = 10.64$ host, TYC
2619-1057-1, has $T_{\rm eff} = 6278 \pm 51$ K, $\log{g_\star} =
3.89^{+0.054}_{-0.051}$, and [Fe/H] = $0.19^{+0.083}_{-0.085}$, with an
inferred mass $M_{\star} = 1.59^{+0.071}_{-0.091} M_\odot$ and radius $R_\star
= 2.37 \pm 0.18 R_\odot$. The planetary companion has $M_{\rm P} = 0.95 \pm
0.14 M_{\rm J}$, $R_{\rm P} = 1.79^{+0.18}_{-0.17} R_{\rm J}$, $\log{g_{\rm P}}
= 2.87^{+0.097}_{-0.098}$, and density $\rho_{\rm P} = 0.21^{+0.075}_{-0.054}$
g cm$^{-3}$, making it one of the most inflated giant planets known. The time
of inferior conjunction in ${\rm BJD_{TDB}}$ is $2457088.692055 \pm 0.0009$ and
the period is $P = 5.0316144 \pm 0.0000306$ days. Despite the relatively large
separation of $\sim0.07$ AU implied by its $\sim 5.03$-day orbital period,
KELT-12b receives significant flux of $2.93^{+0.33}_{-0.30} \times 10^9$ erg
s$^{-1}$ cm$^{-2}$ from its host. We compare the radii and insolations of
transiting gas-giant planets around hot ($T_{\rm eff} \geq 6250$ K) and cool
stars, noting that the observed paucity of known transiting giants around hot
stars with low insolation is likely due to selection effects. We underscore the
significance of long-term ground-based monitoring of hot stars and space-based
targeting of hot stars with the Transiting Exoplanet Survey Satellite (TESS) to
search for inflated giants in longer-period orbits.


title:
Orthogonal and Non-Orthogonal Tight Binding parameters for III-V
  Semiconductors Nitrides

abstract:
  A simulated annealing (SA) approach is employed in the determination of
different tight binding (TB) sets of parameters for the nitride semiconductors
AlN, GaN and InN, as well their limitations and potentialities are also
discussed. Two kinds of atomic basis set are considered: (\textit{i}) the
orthogonal $sp^3s*$ with interaction up to second neighbors and (\textit{ii}) a
$spd$ non-orthogonal set, with the Hamiltonian matrix elements calculated
within the Extended H\"uckel Theory (EHT) prescriptions. For the non-orthogonal
method, TB parameters are given for both zincblend and wurtzite crystalline
structures.


title: Magnetic field generation by intermittent convection

abstract:
  Magnetic field generation in three-dimensional Rayleigh-B\'enard convection
of an electrically conducting fluid is studied numerically by fixing the
Prandtl number at $P=0.3$ and varying the Rayleigh number (Ra) as a control
parameter. A recently reported route to hyperchaos involving quasiperiodic
regimes, crises and chaotic intermittent attractors is followed, and the
critical magnetic Prandtl number ($P_m^c$) for dynamo action is determined as a
function of Ra. A mechanism for the onset of intermittency in the magnetic
energy is described, the most beneficial convective regimes for dynamo action
in this transition to weak turbulence are identified, and the impact of
intermittency on the dependence of $P_m^c$ on Ra is discussed.


title:
Bayesian aggregation of two forecasts in the partial information
  framework

abstract:
  We generalize the results of \cite{SPU, SJPU} by showing how the Gaussian
aggregator may be computed in a setting where parameter estimation is not
required. We proceed to provide an explicit formula for a "one-shot"
aggregation problem with two forecasters.


title: A proof of the refined class number formula of Gross

abstract:
  In 1988, Gross proposed a conjectural congruence between Stickelberger
elements and algebraic regulators, which is often referred to as the refined
class number formula. In this paper, we prove this congruence.


title:
Sizable NSI from the $SU(2)_L$ scalar doublet-singlet mixing and the
  implications in DUNE

abstract:
  We propose a novel and simple mechanism where sizable effects of non-standard
interactions (NSI) in neutrino propagation are induced from the mixing between
an electrophilic second Higgs doublet and a charged singlet. The mixing arises
from a dimensionful coupling of the scalar doublet and singlet to the standard
model Higgs boson. In light of the small mass, the light mass eigenstate from
the doublet-singlet mixing can generate much larger NSI than those induced by
the heavy eigenstate. We show that a sizable NSI $\varepsilon_{e\tau}$ ($\sim
0.3$) can be attained without being excluded by a variety of experimental
constraints. Furthermore, we demonstrate that NSI can mimic effects of the
Dirac CP phase in the neutrino mixing matrix but they can potentially be
disentangled by future long-baseline neutrino experiments, such as the Deep
Underground Neutrino Experiment (DUNE).


title:
Adaptive Restart and CEGAR-based Solver for Inverting Cryptographic Hash
  Functions

abstract:
  SAT solvers are increasingly being used for cryptanalysis of hash functions
and symmetric encryption schemes. Inspired by this trend, we present MapleCrypt
which is a SAT solver-based cryptanalysis tool for inverting hash functions. We
reduce the hash function inversion problem for fixed targets into the
satisfiability problem for Boolean logic, and use MapleCrypt to construct
preimages for these targets. MapleCrypt has two key features, namely, a
multi-armed bandit based adaptive restart (MABR) policy and a
counterexample-guided abstraction refinement (CEGAR) technique. The MABR
technique uses reinforcement learning to adaptively choose between different
restart policies during the run of the solver. The CEGAR technique abstracts
away certain steps of the input hash function, replacing them with the identity
function, and verifies whether the solution constructed by MapleCrypt indeed
hashes to the previously fixed targets. If it is determined that the solution
produced is spurious, the abstraction is refined until a correct inversion to
the input hash target is produced. We show that the resultant system is faster
for inverting the SHA-1 hash function than state-of-the-art inversion tools.


title:
Adaptive Position-Based Fluids: Improving Performance of Fluid
  Simulations for Real-Time Applications

abstract:
  The Position Based Fluids (PBF) method is a state-of-the-art approach for
fluid simulations in the context of real-time applications like games. It uses
an iterative solver concept that tries to maintain a constant fluid density
(incompressibility) to realize incompressible fluids like water. However,
larger fluid volumes that consist of several hundred thousand particles (e.g.
for the simulation of oceans) require many iterations and a lot of simulation
power. We present a lightweight and easy-to-integrate extension to PBF that
adaptively adjusts the number of solver iterations on a fine-grained basis.
Using a novel adaptive-simulation approach, we are able to achieve significant
improvements in performance on our evaluation scenarios while maintaining
high-quality results in terms of visualization quality, which makes it a
perfect choice for game developers. Furthermore, our method does not weaken the
advantages of prior work and seamlessly integrates into other position-based
methods for physically-based simulations.


title: Pretty Good State Transfer in Qubit Chains - The Heisenberg Hamiltonian

abstract:
  Pretty good state transfer in networks of qubits occurs when a
continuous-time quantum walk allows the transmission of a qubit state from one
node of the network to another, with fidelity arbitrarily close to 1. We prove
that in a Heisenberg chain with n qubits there is pretty good state transfer
between the nodes at the j-th and (n-j+1)-th position if n is a power of 2.
Moreover, this condition is also necessary for j=1. We obtain this result by
applying a theorem due to Kronecker about Diophantine approximations, together
with techniques from algebraic graph theory.


title: Extremal limits and Ba\~nados-Silk-West effect

abstract:
  A fascinating property of extremal Kerr black hole (BH) is that it could be
act as a particle accelerator with infinite high center-of-mass (CM) energy
\cite{bsw}. In this note, we would like to discuss about such fascinating
result and to point out that this infinite energy at the event horizon comes
solely due \emph{to the singular nature of the extremal limit}. We also show
that a non-extremal Kerr BH can \emph{not} transform into extremal Kerr BH by
the Ba\~{n}ados-Silk-West mechanism. Moreover, we discuss about three possible
geometries (near extremal, purely extremal and near horizon of extremal Kerr)
of this mechanism. We further prove that near extremal geometry and near
horizon geometry, precisely extremal geometry of extremal Kerr BHs are
qualitatively different. Near extremal geometry and near horizon geometry gives
the CM energy is finite, whereas precisely extremal geometry gives the
diverging energy. Thus, we can argue that extremal Kerr BH and non-extremal
Kerr BH are quite distinct objects. Finally, we show that the CM energy of
collisions of particles not only diverges at infinite red-shift surface
($r_{+}$) but it could also diverges at the ISCO ($r_{isco}$) or at the
circular photon orbit ($r_{cpo}$) or at the marginally bound circular orbit
($r_{mbco}$) or at the Cauchy horizon i.e. at $r \equiv
r_{isco}=r_{cpo}=r_{mbco}=r_{+}=r_{-}=M$.


title: Optical levitation of high purity nanodiamonds in vacuum without heating

abstract:
  Levitated nanodiamonds containing nitrogen vacancy centres in high vacuum are
a potential test bed for numerous phenomena in fundamental physics. However,
experiments so far have been limited to low vacuum due to heating arising from
optical absorption of the trapping laser. We show that milling pure diamond
creates nanodiamonds that do not heat up as the optical intensity is raised
above 700 GW/m$^2$ below 5 mbar of pressure. This advance now means that the
level of attainable vacuum for nanodiamonds in optical dipole traps is no
longer temperature limited.

categories: physics.optics cond-mat.mes-hall cond-mat.mtrl-sci quant-ph


title:
Extended quandle spaces and shadow homotopy invariants of classical
  links

abstract:
  In 1993, Fenn, Rourke and Sanderson introduced rack spaces and rack homotopy
invariants, and modifications to quandle spaces and quandle homotopy invariants
were introduced by Nosaka in 2011. In this paper, we define the Cayley-type
graph and the extended quandle space of a quandle in analogy to rack and
quandle spaces. Moreover, we construct the shadow homotopy invariant of a
classical link and prove that the shadow homotopy invariant is equal to the
quandle homotopy invariant multiplied by the order of a quandle.


title: Current Fluctuations of the Stationary ASEP and Six-Vertex Model

abstract:
  Our results in this paper are two-fold. First, we consider current
fluctuations of the stationary asymmetric simple exclusion process (ASEP), run
for some long time $T$, and show that they are of order $T^{1 / 3}$ along a
characteristic line. Upon scaling by $T^{1 / 3}$, we establish that these
fluctuations converge to the long-time height fluctuations of the stationary
KPZ equation, that is, to the Baik-Rains distribution. This result has long
been predicted under the context of KPZ universality and in particular extends
upon a number of results in the field, including the work of Ferrari and Spohn
in 2005 (who established the same result for the TASEP), and the work of Balazs
and Seppalainen in 2010 (who established the $T^{1 / 3}$ scaling for the
general ASEP).
  Second, we introduce a class of translation-invariant Gibbs measures that
characterizes a one-parameter family of slopes for an arbitrary ferroelectric,
symmetric six-vertex model. This family of slopes corresponds to what is known
as the conical singularity (or tricritical point) in the free energy profile
for the ferroelectric six-vertex model. We consider fluctuations of the height
function of this model on a large grid of size $T$ and show that they too are
of order $T^{1 / 3}$ along a certain characteristic line; this confirms a
prediction of Bukman and Shore from 1995 stating that the ferroelectric
six-vertex model should exhibit KPZ growth at the conical singularity.
  Upon scaling the height fluctuations by $T^{1 / 3}$, we again recover the
Baik-Rains distribution in the large $T$ limit. Recasting this statement in
terms of the (asymmetric) stochastic six-vertex model confirms a prediction of
Gwa and Spohn from 1992.


title: Covert Bits Through Queues

abstract:
  We consider covert communication using a queuing timing channel in the
presence of a warden. The covert message is encoded using the inter-arrival
times of the packets, and the legitimate receiver and the warden observe the
inter-departure times of the packets from their respective queues. The
transmitter and the legitimate receiver also share a secret key to facilitate
covert communication. We propose achievable schemes that obtain non-zero covert
rate for both exponential and general queues when a sufficiently high rate
secret key is available. This is in contrast to other channel models such as
the Gaussian channel or the discrete memoryless channel where only
$\mathcal{O}(\sqrt{n})$ covert bits can be sent over $n$ channel uses, yielding
a zero covert rate.


title:
A Practical Study of Longitudinal Reference Based Compressed Sensing for
  MRI

abstract:
  Compressed sensing (CS) is a new signal acquisition paradigm that enables the
reconstruction of signals and images from a low number of samples. A
particularly exciting application of CS is Magnetic Resonance Imaging (MRI),
where CS significantly speeds up scan time by requiring far fewer measurements
than standard MRI techniques. Such a reduction in sampling time leads to less
power consumption, less need for patient sedation, and more accurate images.
This accuracy increase is especially pronounced in pediatric MRI where patients
have trouble being still for long scan periods. Although such gains are already
significant, even further improvements can be made by utilizing past MRI scans
of the same patient. Many patients require repeated scans over a period of time
in order to track illnesses and the prior scans can be used as references for
the current image. This allows samples to be taken adaptively, based on both
the prior scan and the current measurements.
  Work by Weizman has shown that so-called reference based adaptive-weighted
temporal Compressed Sensing MRI (LACS-MRI) requires far fewer samples than
standard Compressed Sensing (CS) to achieve the same reconstruction
signal-to-noise ratio (RSNR). The method uses a mixture of reference-based and
adaptive-sampling. In this work, we test this methodology by using various
adaptive sensing schemes, reconstruction methods, and image types. We create a
thorough catalog of reconstruction behavior and success rates that is
interesting from a mathematical point of view and is useful for practitioners.
We also solve a grayscale compensation toy problem that supports the
insensitivity of LACS-MRI to changes in MRI acquisition parameters and thus
showcases the reliability of LACS-MRI in possible clinical situations.


title: Thin shells joining local cosmic string geometries

abstract:
  In this article we present a theoretical construction of spacetimes with a
thin shell that joins two different local cosmic string geometries. We study
two types of global manifolds, one representing spacetimes with a thin shell
surrounding a cosmic string or an empty region with Minkowski metric, and the
other corresponding to wormholes which are not symmetric across the throat
located at the shell. We analyze the stability of the static configurations
under perturbations preserving the cylindrical symmetry. For both types of
geometries we find that the static configurations can be stable for suitable
values of the parameters.


title: Collinear limits beyond the leading order from the scattering equations

abstract:
  The structure of tree-level scattering amplitudes for collinear massless
bosons is studied beyond their leading splitting function behavior. These
near-collinear limits at sub-leading order are best studied using the
Cachazo-He-Yuan (CHY) formulation of the S-matrix based on the scattering
equations. We compute the collinear limits for gluons, gravitons and scalars.
It is shown that the CHY integrand for an n-particle gluon scattering amplitude
in the collinear limit at sub-leading order is expressed as a convolution of an
(n-1)-particle gluon integrand and a collinear kernel integrand, which is
universal. Our representation is shown to obey recently proposed amplitude
relations in which the collinear gluons of same helicity are replaced by a
single graviton. Finally, we extend our analysis to effective field theories
and study the collinear limit of the non-linear sigma model,
Einstein-Maxwell-Scalar and Yang-Mills-Scalar theory.


title:
Distinguishing coherent from incoherent charge transport in linear
  triple quantum dots

abstract:
  A fundamental question in quantum transport is how quantum coherence
influences charge transfer through nanostructures. We address this issue for
linear triple quantum dots by comparison of a Lindblad density matrix
description with a Pauli rate equation approach and analyze the corresponding
zero-frequency counting statistics for coherent and sequential charge
tunneling, respectively. The impact of decaying coherences of the density
matrix due to dephasing is also studied. Our findings reveal that the
sensitivity to coherence shown by shot noise and skewness, in particular in the
limit of large coupling to the drain reservoir, can be used to unambiguously
evidence coherent processes involved in charge transport across triple quantum
dots. Our analytical results are obtained by using the characteristic
polynomial approach to full counting statistics.


title: Non-Abelian 3d Bosonization and Quantum Hall States

abstract:
  Bosonization dualities relate two different Chern-Simons-matter theories,
with bosonic matter on one side replaced by fermionic matter on the other. We
first describe a more general class of non-Abelian bosonization dualities. We
then explore the non-relativistic physics of these theories in the quantum Hall
regime. The bosonic theory lies in a condensed phase and admits vortices which
are known to form a non-Abelian quantum Hall state. We ask how this same
physics arises in the fermionic theory. We find that a condensed boson
corresponds to a fully filled Landau level of fermions, while bosonic vortices
map to fermionic holes. We confirm that the ground state of the two theories is
indeed described by the same quantum Hall wavefunction.


title:
Power Spectral Density of Magnetization Dynamics Driven by a Jump-Noise
  Process

abstract:
  Random magnetization dynamics driven by a jump-noise process is reduced to
stochastic magnetic energy dynamics on specific graphs using an averaging
technique. An approach to analyzing stochastic energy dynamics on graphs is
presented and applied to the calculation of power spectral density of random
magnetization dynamics. An eigenvalue technique for computing the power
spectral density under specific cases is also presented and illustrated by
numerical results.


title: Black hole thermodynamics, stringy dualities and double field theory

abstract:
  We discuss black hole thermodynamics in the manifestly duality invariant
formalism of double field theory (DFT). We reformulate and prove the first law
of black hole thermodynamics in DFT, using the covariant phase space approach.
After splitting the full O(D, D) invariant DFT into a Kaluza-Klein-inspired
form where only n coordinates are doubled, our results provide explicit duality
invariant mass and entropy formulas. We illustrate how this works by discussing
the black fundamental string solution and its T-duals.


title:
Sound shell model for acoustic gravitational wave production at a
  first-order phase transition in the early Universe

abstract:
  A model for the acoustic production of gravitational waves at a first order
phase transition is presented. The source of gravitational radiation is the
sound waves generated by the explosive growth of bubbles of the stable phase.
The model assumes that the sound waves are linear and that their power spectrum
is determined by the characteristic form of the sound shell around the
expanding bubble. The predicted power spectrum has two length scales, the
average bubble separation and the sound shell width when the bubbles collide.
The peak of the power spectrum is at wavenumbers set by the sound shell width.
For higher wavenumber $k$, the power spectrum decreases as $k^{-3}$. At
wavenumbers below the inverse bubble separation, the power spectrum goes as
$k^5$. For bubble wall speeds near the speed of sound where these two length
scales are distinguished, there is an intermediate $k^{1}$ power law. The
detailed dependence of the power spectrum on the wall speed and the other
parameters of the phase transition raises the possibility of their constraint
or measurement at a future space-based gravitational wave observatory such as
eLISA.


title:
Blending bias impacts the host halo masses derived from a
  cross-correlation analysis of bright sub-millimetre galaxies

abstract:
  Placing bright sub-millimetre galaxies (SMGs) within the broader context of
galaxy formation and evolution requires accurate measurements of their
clustering, which can constrain the masses of their host dark matter halos.
Recent work has shown that the clustering measurements of these galaxies may be
affected by a `blending bias,' which results in the angular correlation
function of the sources extracted from single-dish imaging surveys being
boosted relative to that of the underlying galaxies. This is due to confusion
introduced by the coarse angular resolution of the single-dish telescope and
could lead to the inferred halo masses being significantly overestimated. We
investigate the extent to which this bias affects the measurement of the
correlation function of SMGs when it is derived via a cross-correlation with a
more abundant galaxy population. We find that the blending bias is essentially
the same as in the auto-correlation case and conclude that the best way to
reduce its effects is to calculate the angular correlation function using SMGs
in narrow redshift bins. Blending bias causes the inferred host halo masses of
the SMGs to be overestimated by a factor of $\sim6$ when a redshift interval of
$\delta z=3$ is used. However, this reduces to a factor of $\sim2$ for $\delta
z=0.5$. The broadening of photometric redshift probability distributions with
increasing redshift can therefore impart a mild halo `downsizing' effect onto
the inferred host halo masses, though this trend is not as strong as seen in
recent observational studies.


title:
The relationship between mono-abundance and mono-age stellar populations
  in the Milky Way disk

abstract:
  Studying the Milky Way disk structure using stars in narrow bins of [Fe/H]
and [alpha/Fe] has recently been proposed as a powerful method to understand
the Galactic thick and thin disk formation. It has been assumed so far that
these mono-abundance populations (MAPs) are also coeval, or mono-age,
populations. Here we study this relationship for a Milky Way chemo-dynamical
model and show that equivalence between MAPs and mono-age populations exists
only for the high-[alpha/Fe] tail, where the chemical evolution curves of
different Galactic radii are far apart. At lower [alpha/Fe]-values a MAP is
composed of stars with a range in ages, even for small observational
uncertainties and a small MAP bin size. Due to the disk inside-out formation,
for these MAPs younger stars are typically located at larger radii, which
results in negative radial age gradients that can be as large as 2 Gyr/kpc.
Positive radial age gradients can result for MAPs at the lowest [alpha/Fe] and
highest [Fe/H] end. Such variations with age prevent the simple interpretation
of observations for which accurate ages are not available. Studying the
variation with radius of the stellar surface density and scale-height in our
model, we find good agreement to recent analyses of the APOGEE red-clump (RC)
sample when 1-4 Gyr old stars dominate (as expected for the RC). Our results
suggest that the APOGEE data are consistent with a Milky Way model for which
mono-age populations flare for all ages. We propose observational tests for the
validity of our predictions and argue that using accurate age measurements,
such as from asteroseismology, is crucial for putting constraints on the
Galactic formation and evolution.


title: An Efficient Character-Level Neural Machine Translation

abstract:
  Neural machine translation aims at building a single large neural network
that can be trained to maximize translation performance. The encoder-decoder
architecture with an attention mechanism achieves a translation performance
comparable to the existing state-of-the-art phrase-based systems on the task of
English-to-French translation. However, the use of large vocabulary becomes the
bottleneck in both training and improving the performance. In this paper, we
propose an efficient architecture to train a deep character-level neural
machine translation by introducing a decimator and an interpolator. The
decimator is used to sample the source sequence before encoding while the
interpolator is used to resample after decoding. Such a deep model has two
major advantages. It avoids the large vocabulary issue radically; at the same
time, it is much faster and more memory-efficient in training than conventional
character-based models. More interestingly, our model is able to translate the
misspelled word like human beings.


title: Transient Instability of Rapidly Rotating Black Holes

abstract:
  We analytically study the linear response of a near-extremal Kerr black hole
to external scalar, electromagnetic, and gravitational field perturbations. We
show that the energy density, electromagnetic field strength, and tidal force
experienced by infalling observers exhibit transient growth near the horizon.
The growth lasts arbitrarily long in the extremal limit, reproducing the
horizon instability of extremal Kerr. We explain these results in terms of
near-horizon geometry and discuss potential astrophysical implications.


title: Entangled Cloning of Stabilizer Codes and Free Fermions

abstract:
  Though the no-cloning theorem [1] prohibits exact replication of arbitrary
quantum states, there are many instances in quantum information processing and
entanglement measurement in which a weaker form of cloning may be useful. Here,
I provide a construction for generating an "entangled clone" for a particular
but rather expansive and rich class of states. Given a stabilizer code or free
fermion Hamiltonian, this construction generates an exact entangled clone of
the original ground state, in the sense that the entanglement between the
original and the exact copy can be tuned to be arbitrarily small but finite, or
large, and the relation between the original and the copy can also be modified
to some extent. For example, this work focuses on generating time-reversed
copies of stabilizer codes and particle-hole transformed ground states of free
fermion systems, although untransformed clones can also be generated. The
protocol leverages entanglement to simulate a transformed copy of the
Hamiltonian without having to physically implement it and can potentially be
realized in superconducting qubits or ultracold atomic systems.


title:
Revealing frustrated local moment model for pressurized hyperhoneycomb
  iridate: paving a way toward quantum spin liquid

abstract:
  There have been tremendous experimental and theoretical efforts toward
discovery of quantum spin liquid phase in honeycomb-based-lattice materials
with strong spin-orbit coupling. Here the bond-dependent Kitaev interaction
between local moments provides strong magnetic frustration and if it is the
only interaction present in the system, it will lead to an exactly solvable
quantum spin liquid ground state. In all of these materials, however, the
ground state is in a magnetically ordered phase due to additional interactions
between local moments. Recently, it has been reported that the magnetic order
in hyperhoneycomb material, $\beta$-Li$_2$IrO$_3$, is suppressed upon applying
hydrostatic pressure and the resulting state becomes a quantum paramagnet or
possibly a quantum spin liquid. Using ab-initio computations and strong
coupling expansion, we investigate the lattice structure and resulting local
moment model in pressurized $\beta$-Li$_2$IrO$_3$. Remarkably, the dominant
interaction under high pressure is not the Kitaev interaction nor further
neighbor interactions, but a different kind of bond-dependent interaction. This
leads to strong magnetic frustration and may provide a platform for discovery
of a new kind of quantum spin liquid ground state.


title:
The Next Generation Virgo cluster Survey (NGVS). XXV. Fiducial
  panchromatic colors of Virgo core globular clusters and their comparison to
  model predictions

abstract:
  The central region of the Virgo cluster of galaxies contains thousands of
globular clusters (GCs), an order of magnitude more than the numbers found in
the Local Group. Relics of early star formation epochs in the universe, these
GCs also provide ideal targets to test our understanding of the Spectral Energy
Distributions (SEDs) of old stellar populations. Based on photometric data from
the Next Generation Virgo cluster Survey (NGVS) and its near-infrared
counterpart NGVS-IR, we select a robust sample of 1846 GCs with excellent
photometry and spanning the full range of colors present in the Virgo core. The
selection exploits the well defined locus of GCs in the uiK diagram and the
fact that the globular clusters are marginally resolved in the images. We show
that the GCs define a narrow sequence in 5-dimensional color space, with
limited but real dispersion around the mean sequence. The comparison of these
SEDs with the predictions of eleven widely used population synthesis models
highlights differences between models, and also shows that no single model
adequately matches the data in all colors. We discuss possible causes for some
of these discrepancies. Forthcoming papers of this series will examine how best
to estimate photometric metallicities in this context, and compare the Virgo
globular cluster colors with those in other environments.


title:
Response of the Milky Way's disc to the Large Magellanic Cloud in a
  first infall scenario

abstract:
  We present N-body and hydrodynamical simulations of the response of the Milky
Way's baryonic disc to the presence of the Large Magellanic Cloud during a
first infall scenario. For a fiducial galactic model reproducing the gross
properties of the Galaxy, we explore a set of six initial conditions for the
LMC of varying mass which all evolve to fit the measured constraints on its
current position and velocity with respect to the Galactic Center. We find that
the LMC can produce strong disturbances - warping of the stellar and gaseous
discs - in the Galaxy, without violating constraints from the phase-space
distribution of stars in the Solar Neighbourhood. All models correctly
reproduce the phases of the warp and its anti-symmetrical shape about the
disc's mid-plane. If the warp is due to the LMC alone, then the largest mass
model is favoured ($2.5\times10^{11}\,\rm{M_{\odot}}$). Still, some
quantitative discrepancies remain, including deficits in height of $\Delta
Z=0.7 \, \rm{kpc}$ at $R=22 \,\rm{kpc}$ and $\Delta Z=0.7\, \rm{kpc}$ at $R=16
\,\rm{kpc}$. This suggests that even higher infall masses for the LMC's halo
are allowed by the data. A comparison with the vertical perturbations induced
by a heavy Sagittarius dSph model ($10^{11}\,\rm{M_{\odot}}$) suggest that
positive interference with the LMC warp is expected at $R=16 \, \rm{kpc}$. We
conclude that the vertical structure of the Galactic disc beyond the Solar
Neighbourhood may jointly be shaped by its most massive satellites. As such,
the current structure of the MW suggests we are seeing the process of disc
heating by satellite interactions in action.


title: Zero Modes and Entanglement Entropy

abstract:
  Ultraviolet divergences are widely discussed in studies of entanglement
entropy. Also present, but much less understood, are infrared divergences due
to zero modes in the field theory. In this note, we discuss the importance of
carefully handling zero modes in entanglement entropy. We give an explicit
example for a chain of harmonic oscillators in 1D, where a mass regulator is
necessary to avoid an infrared divergence due to a zero mode. We also comment
on a surprising contribution of the zero mode to the UV-scaling of the
entanglement entropy.


title: Secretly Asymmetric Dark Matter

abstract:
  We study a mechanism where the dark matter number density today arises from
asymmetries generated in the dark sector in the early universe, even though
total dark matter number remains zero throughout the history of the universe.
The dark matter population today can be completely symmetric, with annihilation
rates above those expected from thermal WIMPs. We give a simple example of this
mechanism using a benchmark model of flavored dark matter. We discuss the
experimental signatures of this setup, which arise mainly from the sector that
annihilates the symmetric component of dark matter.


title: R-Parity violation in F-Theory

abstract:
  We discuss R-parity violation (RPV) in semi-local and local F-theory
constructions. We first present a detailed analysis of all possible
combinations of RPV operators arising from semi-local F-theory spectral cover
constructions, assuming an $SU(5)$ GUT. We provide a classification of all
possible allowed combinations of RPV operators originating from operators of
the form $10\cdot \bar 5\cdot \bar 5$, including the effect of $U(1)$ fluxes
with global restrictions. We then relax the global constraints and perform
explicit computations of the bottom/tau and RPV Yukawa couplings, at an
$SO(12)$ local point of enhancement in the presence of general fluxes subject
only to local flux restrictions. We compare our results to the experimental
limits on each allowed RPV operator, and show that operators such as $LLe^c$,
$LQd^c$ and $u^cd^cd^c$ may be present separately within current bounds,
possibly on the edge of observability, suggesting lepton number violation or
neutron-antineutron oscillations could constrain F-theory models.


title: Sub-THz thermally activated-electrical conductivity of CdS thin films

abstract:
  The electrical conductivity of a CdS thin film, controlled by grain
structures is essential to enhance its photoconductivity to be able to be fit
as a window material in CdS/CdTe heterojunction solar cell. In order to
characterize a thin film, electromagnetically, we employed an open cavity
resonator with a sub-millimeter VNA (Vector Network Analyzer). Our technique is
capable of measuring complex dielectric permittivity, $\tilde{\epsilon}$, of a
photovoltaic film as thin as 0.1 $\mu$m. We measured the real part of the
complex dielectric permittivity, $\epsilon_{re}$, and electrical conductivity,
$\sigma_{re}$ (derived from the imaginary part, $\epsilon_{im}$), of unannealed
and annealed CdS films with thicknesses $\sim$ 0.15 $\mu$m on $\sim$ 3 mm
thick-borosillicate glass substrates, at room temperature. We obtain the
(thermally activated) electrical conductivity between 100 and 312 GHz, which is
less in annealed samples than in unannealed one by $\sim$ 2 orders of
magnitude. Contrary to our expectations, the carrier concentrations extracted
from these data by fitting a Drude model, are $\sim$ 10$^{16}$ cm$^{-3}$
(unannealed) and $\sim$ 10$^{14}$ cm$^{-3}$ (annealed). We investigate the
connection between grain size and carrier concentration.


title: M2-Branes And The (2,0) Superalgebra

abstract:
  We present a generalization of the six-dimensional (2,0) system of
arXiv:1007.2982 to include a constant abelian 3-form. For vanishing 3-form this
system is known to provide a variety descriptions of parallel M5-branes. For a
particular choice of 3-form the system is shown to reduce to that of two
M2-branes. Thus this generalised (2,0) system provides a unified description of
two parallel M2-branes or M5-branes.


title: Leading-twist distribution amplitudes of scalar- and vector-mesons

abstract:
  A symmetry-preserving truncation of the two-body light-quark bound-state
problem in relativistic quantum field theory is used to calculate the
leading-twist parton distribution amplitudes (PDAs) of scalar systems, both
ground-state and radial excitations, and the radial excitations of vector
mesons. Owing to the fact that the scale-independent leptonic decay constant of
a scalar meson constituted from equal-mass valence-constituents vanishes, it is
found that the PDA of a given scalar system possesses one more zero than that
of an analogous vector meson. Consequently, whereas the mean light-front
relative momentum of the valence-constituents within a vector meson is zero,
that within a scalar meson is large, an outcome which hints at a greater role
for light-front angular momentum in systems classified as $P$-wave in quantum
mechanical models. Values for the scale-dependent decay constants of
ground-state scalar and vector systems are a by-product of this analysis, and
they turn out to be roughly equal, viz. $\simeq 0.2\,$GeV at an hadronic scale.
In addition, it is confirmed that the dilation characterising ground-state PDAs
is manifest in the PDAs of radial excitations too. The impact of
$SU(3)$-flavour symmetry breaking is also considered. When compared with
pseudoscalar states, it is a little stronger in scalar systems, but the size is
nevertheless determined by the flavour-dependence of dynamical chiral symmetry
breaking and the PDAs are still skewed toward the heavier valence-quark in
asymmetric systems.


title: Conditional Mutual Information of Bipartite Unitaries and Scrambling

abstract:
  One way to diagnose chaos in bipartite unitary channels is via the tripartite
information of the corresponding Choi state, which for certain choices of the
subsystems reduces to the negative conditional mutual information (CMI). We
study this quantity from a quantum information-theoretic perspective to clarify
its role in diagnosing scrambling. When the CMI is zero, we find that the
channel has a special normal form consisting of local channels between
individual inputs and outputs. However, we find that arbitrarily low CMI does
not imply arbitrary proximity to a channel of this form, although it does imply
a type of approximate recoverability of one of the inputs. When the CMI is
maximal, we find that the residual channel from an individual input to an
individual output is completely depolarizing when the other input is maximally
mixed. However, we again find that this result is not robust. We also extend
some of these results to the multipartite case and to the case of Haar-random
pure input states. Finally, we look at the relationship between tripartite
information and its Renyi-2 version which is directly related to
out-of-time-order correlation functions. In particular, we demonstrate an
arbitrarily large gap between the two quantities.


title:
Laboratory measurements compellingly support charge-exchange mechanism
  for the 'dark matter' $\sim$3.5 keV X-ray line

abstract:
  The reported observations of an unidentified X-ray line feature at $\sim$3.5
keV have driven a lively discussion about its possible dark matter origin.
Motivated by this, we have measured the \emph{K}-shell X-ray spectra of highly
ionized bare sulfur ions following charge exchange with gaseous molecules in an
electron beam ion trap, as a source of or a contributor to this X-ray line. We
produce $\mathrm{S}^{16+}$ and $\mathrm{S}^{15+}$ ions and let them capture
electrons in collision with those molecules with the electron beam turned off
while recording X-ray spectra. We observed a charge-exchanged-induced X-ray
feature at the Lyman series limit (3.47 $\pm$ 0.06 keV). The inferred X-ray
energy is in full agreement with the reported astrophysical observations and
supports the novel scenario proposed by Gu and Kaastra (A \& A \textbf{584},
{L11} (2015)).

categories: astro-ph.HE astro-ph.CO astro-ph.GA physics.atom-ph physics.plasm-ph


title:
Behaviour of linear multifractional stable motion: membership of a
  critical H\"older space

abstract:
  The study of path behaviour of stochastic processes is a classical topic in
probability theory and related areas. In this frame, a natural question one can
address is: whether or not sample paths belong to a critical H\"older space?
The answer to this question is negative in the case of Brownian motion and many
other stochastic processes: it is well-known that despite the fact that
Brownian paths satisfy, on each compact interval $I$, a H\"older condition of
any order strictly less than $1/2$, they fail to belong to the critical
H\"older space $\mathcal{C}^{1/2}(I)$. In this article, we show that a
different phenomenon happens in the case of linear multifractional stable
motion (LMSM): for any given compact interval one can find a critical H\"older
space to which sample paths belong. Among other things, this result improves an
upper estimate, recently derived in Bierm\'e, Lacaux (2013), on behaviour of
LMSM, by showing that the logarithmic factor in it is not needed.


title: The awakening of a classical nova from hibernation

abstract:
  Cataclysmic variable stars (CVs) are close binary systems consisting of a
white dwarf (primary) that is accreting matter from a low-mass companion star
(secondary). From time to time such systems undergo large-amplitude
brightenings. The most spectacular eruptions, over $10^4$ times in brightness,
occur in classical novae and are caused by a thermonuclear runaway on the
surface of the white dwarf. Such eruptions are thought to recur on timescales
of $10^4-10^6$. In between, the system's properties depend primarily on the
mass-transfer rate: if it is lower than a $10^{-9} M_{\odot}$/year, the
accretion becomes unstable and the matter is dumped onto the white dwarf during
quasi-periodic dwarf nova outbursts. The hibernation hypothesis predicts that
nova eruptions strongly affect the mass-transfer rate, keeping it high for
centuries after the event. Subsequently, the mass-transfer rate should
significantly decrease for $10^3-10^6$ years, starting the hibernation phase.
After that the nova awakes again - with accretion returning to the pre-eruption
level and leading to a new nova explosion. The hibernation model predicts
cyclical evolution of CVs through phases of high and low mass-transfer. The
theory gained some support from the discovery of ancient nova shells around
dwarf novae Z Cam and AT Cnc, but direct evidence for considerable
mass-transfer changes prior, during and after nova eruptions has not hitherto
been found. Here we report long-term observations of the classical nova V1213
Cen (Nova Cen 2009) covering its pre- and post-eruption phases. Within the six
years before the explosion, the system revealed dwarf nova outbursts indicative
of a low mass-transfer rate. The post-nova is two orders of magnitude brighter
than the pre-nova at minimum light with no trace of dwarf nova behavior,
implying that the mass-transfer rate increased considerably as a result of the
nova explosion.


title: One-loop Wilson loops and the particle-interface potential in AdS/dCFT

abstract:
  We initiate the calculation of quantum corrections to Wilson loops in a class
of four-dimensional defect conformal field theories with vacuum expectation
values based on N=4 super Yang-Mills theory. Concretely, we consider an
infinite straight Wilson line, obtaining explicit results for the one-loop
correction to its expectation value in the large-N limit. This allows us to
extract the particle-interface potential of the theory. In a further
double-scaling limit, we compare our results to those of a previous calculation
in the dual string-theory set-up consisting of a D5-D3 probe-brane system with
flux, and we find perfect agreement.


title: Scrutinizing a di-photon resonance at the LHC through Moscow zero

abstract:
  The ATLAS and CMS collaborations have recently released their new analyses of
the diphoton searches. We look in detail the consequences of their results
deriving strong constraints on models where a scalar resonance $s$ decays into
two light pseudoscalars which in turn decay into two pairs of collimated
photons, mis-identified with two real photons. In our construction, all mass
terms are generated dynamically, and only one pair of vector-like fermions
generate couplings which will be probed using the upcoming LHC data. Moreover,
we show that a stable dark matter candidate, respecting the cosmological
constraints, is naturally affordable in the model.


title: Painleve equations, vector fields, and ranks in differential fields

abstract:
  Model theoretic ranks of solutions to Painleve equations are calculated, and
the type of the generic solution of the second Painleve equation is shown to be
disintegrated, strengthening a theorem of Nagloo. A question of Hrushovski and
Scanlon regarding Lascar rank and Morley rank in differential fields is
answered using planar vector fields.


title:
Bayesian Mass Estimates of the Milky Way II: The dark and light sides of
  parameter assumptions

abstract:
  We present mass and mass profile estimates for the Milky Way Galaxy using the
Bayesian analysis developed by Eadie et al (2015b) and using globular clusters
(GCs) as tracers of the Galactic potential. The dark matter and GCs are assumed
to follow different spatial distributions; we assume power-law model profiles
and use the model distribution functions described in Evans et al. (1997);
Deason et al (2011, 2012a). We explore the relationships between assumptions
about model parameters and how these assumptions affect mass profile estimates.
We also explore how using subsamples of the GC population beyond certain radii
affect mass estimates. After exploring the posterior distributions of different
parameter assumption scenarios, we conclude that a conservative estimate of the
Galaxy's mass within 125kpc is $5.22\times10^{11} M_{\odot}$, with a $50\%$
probability region of $(4.79, 5.63) \times10^{11} M_{\odot}$. Extrapolating out
to the virial radius, we obtain a virial mass for the Milky Way of
$6.82\times10^{11} M_{\odot}$ with $50\%$ credible region of $(6.06, 7.53)
\times 10^{11} M_{\odot}$ ($r_{vir}=185^{+7}_{-7}$kpc). If we consider only the
GCs beyond 10kpc, then the virial mass is $9.02~(5.69, 10.86) \times 10^{11}
M_{\odot}$ ($r_{vir}=198^{+19}_{-24}$kpc). We also arrive at an estimate of the
velocity anisotropy parameter $\beta$ of the GC population, which is
$\beta=0.28$ with a $50\%$ credible region (0.21, 0.35). Interestingly, the
mass estimates are sensitive to both the dark matter halo potential and visible
matter tracer parameters, but are not very sensitive to the anisotropy
parameter.


title: Modeling and Analysis of the APOLLO Lunar Laser Ranging Data

abstract:
  The Earth-Moon-Sun system has traditionally provided the best laboratory for
testing the strong equivalence principle. For a decade, the Apache Point
Observatory Lunar Laser-ranging Operation (APOLLO) has been producing the
world's best lunar laser ranging data. At present, a single observing session
of about an hour yields a distance measurement with uncertainty of about 2~mm,
an order of magnitude advance over the best pre-APOLLO lunar laser ranging
data. However, these superb data have not yet yielded scientific results
commensurate with their accuracy, number, and temporal distribution. There are
two reasons for this. First, even in the relatively clean environment of the
Earth-Moon system, a large number of effects modify the measured distance
importantly and thus need to be included in the analysis model. The second
reason is more complicated. The traditional problem with the analysis of
solar-system metric data is that the physical model must be truncated to avoid
extra parameters that would increase the condition number of the estimator.
Even in a typical APOLLO analysis that does not include parameters of gravity
physics, the condition number is very high: $8 \times 10^{10}$.


title: Faster Sublinear Algorithms using Conditional Sampling

abstract:
  A conditional sampling oracle for a probability distribution D returns
samples from the conditional distribution of D restricted to a specified subset
of the domain. A recent line of work (Chakraborty et al. 2013 and Cannone et
al. 2014) has shown that having access to such a conditional sampling oracle
requires only polylogarithmic or even constant number of samples to solve
distribution testing problems like identity and uniformity. This significantly
improves over the standard sampling model where polynomially many samples are
necessary.
  Inspired by these results, we introduce a computational model based on
conditional sampling to develop sublinear algorithms with exponentially faster
runtimes compared to standard sublinear algorithms. We focus on geometric
optimization problems over points in high dimensional Euclidean space. Access
to these points is provided via a conditional sampling oracle that takes as
input a succinct representation of a subset of the domain and outputs a
uniformly random point in that subset. We study two well studied problems:
k-means clustering and estimating the weight of the minimum spanning tree. In
contrast to prior algorithms for the classic model, our algorithms have time,
space and sample complexity that is polynomial in the dimension and
polylogarithmic in the number of points.
  Finally, we comment on the applicability of the model and compare with
existing ones like streaming, parallel and distributed computational models.


title:
K2 Discovers a Busy Bee: An Unusual Transiting Neptune Found in the
  Beehive Cluster

abstract:
  Open clusters have been the focus of several exoplanet surveys but only a few
planets have so far been discovered. The \emph{Kepler} spacecraft revealed an
abundance of small planets around small, cool stars, therefore, such cluster
members are prime targets for exoplanet transit searches. Kepler's new mission,
K2, is targeting several open clusters and star-forming regions around the
ecliptic to search for transiting planets around their low-mass constituents.
Here, we report the discovery of the first transiting planet in the
intermediate-age (800 Myr) Beehive cluster (Praesepe). K2-95 is a faint
($\mathrm{Kp = 15.5\,mag}$) $\mathrm{M3.0\pm0.5}$ dwarf from K2's Campaign 5
with an effective temperature of $\mathrm{3471 \pm 124\,K}$, approximately
solar metallicity and a radius of $\mathrm{0.402 \pm 0.050 \,R_\odot}$. We
detected a transiting planet with a radius of $\mathrm{3.47^{+0.78}_{-0.53} \,
R_\oplus}$ and an orbital period of 10.134 days. We combined photometry,
medium/high-resolution spectroscopy, adaptive optics/speckle imaging and
archival survey images to rule out any false positive detection scenarios,
validate the planet, and further characterize the system. The planet's radius
is very unusual as M-dwarf field stars rarely have Neptune-sized transiting
planets. The comparatively large radius of K2-95b is consistent with the other
recently discovered cluster planets K2-25b (Hyades) and K2-33b (Upper
Scorpius), indicating systematic differences in their evolutionary states or
formation. These discoveries from K2 provide a snapshot of planet formation and
evolution in cluster environments and thus make excellent laboratories to test
differences between field-star and cluster planet populations.


title:
Developing a statistically powerful measure for quartet tree inference
  using phylogenetic identities and Markov invariants

abstract:
  Recently there has been renewed interest in phylogenetic inference methods
based on phylogenetic invariants, alongside the related Markov invariants.
Broadly speaking, both these approaches give rise to polynomial functions of
sequence site patterns that, in expectation value, either vanish for particular
evolutionary trees (in the case of phylogenetic invariants) or have well
understood transformation properties (in the case of Markov invariants). While
both approaches have been valued for their intrinsic mathematical interest, it
is not clear how they relate to each other, and to what extent they can be used
as practical tools for inference of phylogenetic trees.
  In this paper, by focusing on the special case of binary sequence data and
quartets of taxa, we are able to view these two different polynomial-based
approaches within a common framework. To motivate the discussion, we present
three desirable statistical properties that we argue any phylogenetic method
should satisfy: (1) sensible behaviour under reordering of input sequences; (2)
stability as the taxa evolve independently according to a Markov process; and
(3) ability to detect if the conditions of a continuous-time process are
violated. Motivated by these statistical properties, we develop and explore
several new phylogenetic inference methods. In particular, we develop a
statistical bias-corrected version of the Markov invariants approach which
satisfies all three properties. We also extend previous work by showing that
the phylogenetic invariants can be implemented in such a way as to satisfy
property (3). A simulation study shows that, in comparison to other methods,
our new proposed approach based on bias-corrected Markov invariants is
extremely powerful for phylogenetic inference.


title:
Feedback-regulated star formation and escape of LyC photons from
  mini-haloes during reionisation

abstract:
  Reionisation in the early Universe is likely driven by dwarf galaxies. Using
cosmological radiation-hydrodynamic simulations, we study star formation and
the escape of Lyman continuum (LyC) photons from mini-haloes with $M_{\rm halo}
\le 10^8\,M_\odot$. Our simulations include a new thermo-turbulent star
formation model, non-equilibrium chemistry, and relevant stellar feedback
processes (photoionisation by young massive stars, radiation pressure, and
mechanical supernova explosions). We find that feedback reduces star formation
very efficiently in mini-haloes, resulting in the stellar mass consistent with
the slope and normalisation reported in Kimm \& Cen and the empirical stellar
mass-to-halo mass relation derived in the local Universe. Because star
formation is stochastic and dominated by a few gas clumps, the escape fraction
in mini-haloes is generally determined by radiation feedback (heating due to
photo-ionisation), rather than supernova explosions. We also find that the
photon number-weighted mean escape fraction in mini-haloes is higher
($\sim20$-$40\%$) than that in atomic-cooling haloes, although the
instantaneous fraction in individual haloes varies significantly. The escape
fraction from Pop III stars is found to be significant ($\ge10\%$) only when
the mass is greater than $\sim$100\,\msun. Based on simple analytic
calculations, we show that LyC photons from mini-haloes are, despite their high
escape fractions, of minor importance for reionisation due to inefficient star
formation. We confirm previous claims that stars in atomic-cooling haloes with
masses $10^8\,M_\odot\le M_{\rm halo} \le 10^{11}\,M_\odot$ are likely to be
the most important source of reionisation.


title: Incentivizing Truth-Telling in MPC-based Load Frequency Control

abstract:
  We present a mechanism for socially efficient implementation of model
predictive control (MPC) algorithms for load frequency control (LFC) in the
presence of self-interested power generators. Specifically, we consider a
situation in which the system operator seeks to implement an MPC-based LFC for
aggregated social cost minimization, but necessary information such as
individual generators' cost functions is privately owned. Without appropriate
monetary compensation mechanisms that incentivize truth-telling,
self-interested market participants may be inclined to misreport their private
parameters in an effort to maximize their own profits, which may result in a
loss of social welfare. The main challenge in our framework arises from the
fact that every participant's strategy at any time affects the future state of
other participants; the consequences of such dynamic coupling has not been
fully addressed in the literature on online mechanism design. We propose a
class of real-time monetary compensation schemes that incentivize market
participants to report their private parameters truthfully at every time step,
which enables the system operator to implement MPC-based LFC in a socially
optimal manner.


title: Bounded Turing Reductions and Data Processing Inequalities for Sequences

abstract:
  A data processing inequality states that the quantity of shared information
between two entities (e.g. signals, strings) cannot be significantly increased
when one of the entities is processed by certain kinds of transformations. In
this paper, we prove several data processing inequalities for sequences, where
the transformations are bounded Turing functionals and the shared information
is measured by the lower and upper mutual dimensions between sequences.
  We show that, for all sequences $X,Y,$ and $Z$, if $Z$ is computable
Lipschitz reducible to $X$, then \[ mdim(Z:Y) \leq mdim(X:Y) \text{ and }
Mdim(Z:Y) \leq Mdim(X:Y). \] We also show how to derive different data
processing inequalities by making adjustments to the computable bounds of the
use of a Turing functional.
  The yield of a Turing functional $\Phi^S$ with access to at most $n$ bits of
the oracle $S$ is the smallest input $m \in \mathbb{N}$ such that $\Phi^{S
\upharpoonright n}(m)\uparrow$. We show how to derive reverse data processing
inequalities (i.e., data processing inequalities where the transformation may
significantly increase the shared information between two entities) for
sequences by applying computable bounds to the yield of a Turing functional.


title: Mass Distribution and Bar Formation in Growing Disk Galaxy Models

abstract:
  We report idealized simulations that mimic the growth of galaxy disks
embedded in responsive halos and bulges. The disks manifested an almost
overwhelming tendency to form strong bars that we found very difficult to
prevent. We found that fresh bars formed in growing disks after we had
destroyed the original, indicating that bar formation also afflicts continued
galaxy evolution, and not just the early stages of disk formation. This
behavior raises still more insistently the previously unsolved question of how
some galaxies avoid bars. Since our simulations included only collisionless
star and halo particles, our findings may apply to gas-poor galaxies only;
however the conundrum persists for the substantial unbarred fraction of those
galaxies. Our original objective was to study how internal dynamics rearranged
the distribution of mass in the disk as a generalization of our earlier study
with rigid spherical components. With difficulty, we were able to construct
some models that were not strongly influenced by bars, and found that halo
compression, and angular momentum exchange with the disk did not alter our
earlier conclusion that spiral activity is largely responsible for creating
smooth density profiles and rotation curves.


title: Know Your Enemy: Stealth Configuration-Information Gathering in SDN

abstract:
  Software Defined Networking (SDN) is a network architecture that aims at
providing high flexibility through the separation of the network logic from the
forwarding functions. The industry has already widely adopted SDN and
researchers thoroughly analyzed its vulnerabilities, proposing solutions to
improve its security. However, we believe important security aspects of SDN are
still left uninvestigated. In this paper, we raise the concern of the
possibility for an attacker to obtain knowledge about an SDN network. In
particular, we introduce a novel attack, named Know Your Enemy (KYE), by means
of which an attacker can gather vital information about the configuration of
the network. This information ranges from the configuration of security tools,
such as attack detection thresholds for network scanning, to general network
policies like QoS and network virtualization. Additionally, we show that an
attacker can perform a KYE attack in a stealthy fashion, i.e., without the risk
of being detected. We underline that the vulnerability exploited by the KYE
attack is proper of SDN and is not present in legacy networks. To address the
KYE attack, we also propose an active defense countermeasure based on network
flows obfuscation, which considerably increases the complexity for a successful
attack. Our solution offers provable security guarantees that can be tailored
to the needs of the specific network under consideration


title: Proceedings of the LexSem+Logics Workshop 2016

abstract:
  Lexical semantics continues to play an important role in driving research
directions in NLP, with the recognition and understanding of context becoming
increasingly important in delivering successful outcomes in NLP tasks. Besides
traditional processing areas such as word sense and named entity
disambiguation, the creation and maintenance of dictionaries, annotated corpora
and resources have become cornerstones of lexical semantics research and
produced a wealth of contextual information that NLP processes can exploit. New
efforts both to link and construct from scratch such information - as Linked
Open Data or by way of formal tools coming from logic, ontologies and automated
reasoning - have increased the interoperability and accessibility of resources
for lexical and computational semantics, even in those languages for which they
have previously been limited.
  LexSem+Logics 2016 combines the 1st Workshop on Lexical Semantics for
Lesser-Resources Languages and the 3rd Workshop on Logics and Ontologies. The
accepted papers in our program covered topics across these two areas,
including: the encoding of plurals in Wordnets, the creation of a thesaurus
from multiple sources based on semantic similarity metrics, and the use of
cross-lingual treebanks and annotations for universal part-of-speech tagging.
We also welcomed talks from two distinguished speakers: on Portuguese lexical
knowledge bases (different approaches, results and their application in NLP
tasks) and on new strategies for open information extraction (the capture of
verb-based propositions from massive text corpora).


title: A Note on Relaxation and Rounding in Algorithmic Mechanism Design

abstract:
  In this note, we revisit the \emph{relaxation and rounding} technique
employed several times in algorithmic mechanism design. We try to introduce a
general framework which covers the most significant algorithms in mechanism
design that use the relaxation and rounding technique. We believe that this
framework is not only a generalization of the existing algorithms but also can
be leveraged for further results in algorithmic mechanism design. Before
presenting the framework, we briefly define algorithmic mechanism design, its
connections to game theory and computer science, and the challenges in the
field.


title: Compact and Fast Sensitivity Oracles for Single-Source Distances

abstract:
  Let $s$ denote a distinguished source vertex of a non-negatively real
weighted and undirected graph $G$ with $n$ vertices and $m$ edges. In this
paper we present two efficient \emph{single-source approximate-distance
sensitivity oracles}, namely \emph{compact} data structures which are able to
\emph{quickly} report an approximate (by a multiplicative stretch factor)
distance from $s$ to any node of $G$ following the failure of any edge in $G$.
More precisely, we first present a sensitivity oracle of size $O(n)$ which is
able to report 2-approximate distances from the source in $O(1)$ time. Then, we
further develop our construction by building, for any $0<\epsilon<1$, another
sensitivity oracle having size $O\left(n\cdot \frac{1}{\epsilon} \log
\frac{1}{\epsilon}\right)$, and which is able to report a
$(1+\epsilon)$-approximate distance from $s$ to any vertex of $G$ in
$O\left(\log n\cdot \frac{1}{\epsilon} \log \frac{1}{\epsilon}\right)$ time.
Thus, this latter oracle is essentially optimal as far as size and stretch are
concerned, and it only asks for a logarithmic query time. Finally, our results
are complemented with a space lower bound for the related class of
single-source \emph{additively-stretched} sensitivity oracles, which is helpful
to realize the hardness of designing compact oracles of this type.


title:
On the Charney Conjecture of Data Assimilation Employing Temperature
  Measurements Alone: The Paradigm of 3D Planetary Geostrophic Model

abstract:
  Analyzing the validity and success of a data assimilation algorithm when some
state variable observations are not available is an important problem in
meteorology and engineering. We present an improved data assimilation algorithm
for recovering the exact full reference solution (i.e. the velocity and
temperature) of the 3D Planetary Geostrophic model, at an exponential rate in
time, by employing coarse spatial mesh observations of the temperature alone.
This provides, in the case of this paradigm, a rigorous justification to an
earlier conjecture of Charney which states that temperature history of the
atmosphere, for certain simple atmospheric models, determines all other state
variables.

categories: math.AP physics.ao-ph physics.flu-dyn physics.geo-ph


title:
Non-Uniform Linear Antenna Array Design and Optimization for Millimeter
  Wave Communications

abstract:
  In this paper, we investigate the optimization of non-uniform linear antenna
arrays (NULAs) for millimeter wave (mmWave) line-of-sight (LoS) multiple-input
multiple-output (MIMO) channels. Our focus is on the maximization of the system
effective multiplexing gain (EMG), by optimizing the individual antenna
positions in the transmit/receive NULAs. Here the EMG is defined as the number
of signal streams that are practically supported by the channel at a finite
SNR. We first derive analytical expressions for the asymptotic channel
eigenvalues with arbitrarily deployed NULAs when, asymptotically, the
end-to-end distance is sufficiently large compared to the aperture sizes of the
transmit/receive NULAs. Based on the derived expressions, we prove that, the
asymptotically optimal NULA deployment that maximizes the achievable EMG should
follow the groupwise Fekete-point distribution. Specifically, the antennas
should be physically grouped into K separate uniform linear antenna arrays
(ULAs) with the minimum feasible antenna spacing within each ULA, where K is
the target EMG to be achieved; in addition, the centers of these K ULAs follow
the Fekete-point distribution. We numerically verify the asymptotic optimality
of such an NULA deployment and extend it to a groupwise projected arch type
(PAT) NULA deployment, which provides a more practical option for mmWave LoS
MIMO systems with realistic non-asymptotic configurations. Numerical examples
are provided to demonstrate a significant capacity gain of the optimized NULAs
over traditional ULAs.


title: The Use of Minimal Spanning Trees in Particle Physics

abstract:
  Minimal spanning trees (MSTs) have been used in cosmology and astronomy to
distinguish distributions of points in a multi-dimensional space. They are
essentially unknown in particle physics, however. We briefly define MSTs and
illustrate their properties through a series of examples. We show how they
might be applied to study a typical event sample from a collider experiment and
conclude that MSTs may prove useful in distinguishing different classes of
events.


title:
Faster Principal Component Regression and Stable Matrix Chebyshev
  Approximation

abstract:
  We solve principal component regression (PCR), up to a multiplicative
accuracy $1+\gamma$, by reducing the problem to $\tilde{O}(\gamma^{-1})$
black-box calls of ridge regression. Therefore, our algorithm does not require
any explicit construction of the top principal components, and is suitable for
large-scale PCR instances. In contrast, previous result requires
$\tilde{O}(\gamma^{-2})$ such black-box calls.
  We obtain this result by developing a general stable recurrence formula for
matrix Chebyshev polynomials, and a degree-optimal polynomial approximation to
the matrix sign function. Our techniques may be of independent interests,
especially when designing iterative methods.


title: Inversion of Zeeman splitting of exciton states in InGaAs quantum wells

abstract:
  Zeeman splitting of quantum-confined states of excitons in InGaAs quantum
wells (QWs) is experimentally found to depend strongly on quantization energy.
Moreover, it changes sign when the quantization energy increases with a
decrease in the QW width. In the 87-nm QW, the sign change is observed for the
excited quantum-confined states, which are above the ground state only by a few
meV. A two-step approach for the numerical solution of the two-particle
Schroedinger equation, taking into account the Coulomb interaction and
valence-band coupling, is used for a theoretical justification of the observed
phenomenon. The calculated variation of the g-factor convincingly follows the
dependencies obtained in the experiments.


title:
The Solar Neighborhood XXXVII: The Mass-Luminosity Relation for Main
  Sequence M Dwarfs

abstract:
  We present a Mass-Luminosity Relation (MLR) for red dwarfs spanning a range
of masses from 0.62 Msun to the end of the stellar main sequence at 0.08 Msun.
The relation is based on 47 stars for which dynamical masses have been
determined, primarily using astrometric data from Fine Guidance Sensors (FGS) 3
and 1r, white-light interferometers on the Hubble Space Telescope (HST), and
radial velocity data from McDonald Observatory. For our HST/FGS sample of 15
binaries component mass errors range from 0.4% to 4.0% with a median error of
1.8%. With these and masses from other sources, we construct a V-band MLR for
the lower main sequence with 47 stars, and a K-band MLR with 45 stars with fit
residuals half of those of the V-band.
  We use GJ 831 AB as an analysis example, obtaining an absolute trigonometric
parallax, pi_abs = 125.3 +/- 0.3 milliseconds of arc, with orbital elements
yielding MA = 0.270 +/- 0.004 Msun and MB = 0.145 +/- 0.002 Msun. The mass
precision rivals that derived for eclipsing binaries.
  A remaining major task is the interpretation of the intrinsic cosmic scatter
in the observed MLR for low mass stars in terms of physical effects. In the
meantime, useful mass values can be estimated from the MLR for the ubiquitous
red dwarfs that account for 75% of all stars, with applications ranging from
the characterization of exoplanet host stars to the contribution of red dwarfs
to the mass of the Universe.


title:
Inference of Heating Properties from "Hot" Non-flaring Plasmas in Active
  Region Cores I. Single Nanoflares

abstract:
  The properties expected of "hot" non-flaring plasmas due to nanoflare heating
in active regions are investigated using hydrodynamic modeling tools, including
a two-fluid development of the EBTEL code. Here we study a single nanoflare and
show that while simple models predict an emission measure distribution
extending well above 10 MK that is consistent with cooling by thermal
conduction, many other effects are likely to limit the existence and
detectability of such plasmas. These include: differential heating between
electrons and ions, ionization non-equilibrium and, for short nanoflares, the
time taken for the coronal density to increase. The most useful temperature
range to look for this plasma, often called the "smoking gun" of nanoflare
heating, lies between $10^{6.6}$ and $10^7$ K. Signatures of the actual heating
may be detectable in some instances.


title: An elementary approach to simplexes in thin subsets of Euclidean space

abstract:
  We prove that if the Hausdorff dimension of $E \subset {\Bbb R}^d$, $d \ge
3$, is greater than $\min \left\{ \frac{dk+1}{k+1}, \frac{d+k}{2} \right\},$
then the ${k+1 \choose 2}$-dimensional Lebesgue measure of $T_k(E)$, the set of
congruence classes of $k$-dimensional simplexes with vertices in $E$, is
positive. This improves the best bounds previously known, decreasing the
$\frac{d+k+1}{2}$ threshold obtained in Erdo\u{g}an-Hart-Iosevich (2012) to
$\frac{d+k}{2}$ via a different and conceptually simpler method. We also give a
simpler proof of the $d-\frac{d-1}{2d}$ threshold for $d$-dimensional simplexes
obtained in Greenleaf-Iosevich (2012), Grafakos-Greenleaf-Iosevich-Palsson
(2015).


title: Negative ion formation in lanthanide atoms: Many-body effects

abstract:
  Investigations of low-energy electron-scattering of the lanthanide atoms Eu,
Nd, Tb, Tm demonstrate that electron-correlation effects and core polarization
are the dominant fundamental many-body effects responsible for the formation of
metastable states of negative ions. Ramsauer Townsend minima, shape resonances
and binding energies of the resultant anions are identified and extracted from
the elastic total cross sections calculated using the complex angular momentum
method. The large discrepancy between the recently measured electron affinity
of 0.116 and the previously measured value of 1.053 eV for Eu is resolved.
Also, the previously measured electron affinities for Nd, Tb and Tm are
reconciled and new values are extracted from the calculated total cross
sections. The large electron affinities found here for these atoms, should be
useful in negative ion nanocatalysis, including methane conversion to methanol
without CO2 emission, with significant environmental impact.. The powerful
complex angular momentum method which requires only a few poles, yields
reliable binding energies for the metastable states of negative ions with no a
priori knowledge of experimental or other theoretical data and should be
applicable to other complex systems for the fundamental understanding of their
interactions.


title:
Thin InSb layers with metallic gratings: a novel platform for
  spectrally-selective THz plasmonic sensing

abstract:
  We present a computational study of terahertz optical properties of a
grating-coupled plasmonic structure based on micrometer-thin InSb layers. We
find two strong absorption resonances that we interpret as standing surface
plasmon modes and investigate their dispersion relations, dependence on InSb
thickness, and the spatial distribution of the electric field. The observed
surface plasmon modes are well described by a simple theory of the air/InSb/air
trilayer. The plasmonic response of the grating/InSb structure is highly
sensitive to the dielectric environment and the presence of an analyte (e.g.,
lactose) at the InSb interface, which is promising for terahertz plasmonic
sensor applications. We determine the sensor sensitivity to be 7200 nm per
refractive index unit (or 0.06 THz per refractive index unit). The lower
surface plasmon mode also exhibits a splitting when tuned in resonance with the
vibrational mode of lactose at 1.37 THz. We propose that such interaction
between surface plasmon and vibrational modes can be used as the basis for a
new sensing modality that allows the detection of terahertz vibrational
fingerprints of an analyte.


title: The modulus of Whittaker functions

abstract:
  The paper discusses some properties of the modulus $|W_{k,m}(z)|$ of the
Whittaker function $W_{k,m}(z)$. In particular, completely monotone functions
expressed in terms of $|W_{k,m}(z)|$ are found. The results follow from an
integral representation for products of Whittaker functions due to Erd\'elyi
(1938).