title:
Analysis and Control of Aircraft Longitudinal Dynamics with Large Flight
  Envelopes

abstract:
  The paper contributes towards the development of a unified control approach
for longitudinal aircraft dynamics with large flight envelopes. Prior to the
control design, we analyze the existence and the uniqueness of the equilibrium
orientation along a reference velocity. We show that shape symmetries and
aerodynamic stall phenomena imply the existence of the equilibrium orientation
irrespective of the reference velocity. The equilibrium orientation, however,
is not in general unique, and this may trigger an aircraft loss-of-control for
specific reference velocities. Conditions that ensure the local and the global
uniqueness of the equilibrium orientation are stated. We show that the
uniqueness of the equilibrium orientation is intimately related to the
so-called spherical equivalency, i.e. the existence of a thrust change of
variable rendering the direction of the transformed external force independent
of the vehicle's orientation, as in the case of spherical shapes. Once this
transformation is applied, control laws for reference velocities can be
designed. These laws extend the so-called vectored--thrust control paradigm
%developed for systems subject to orientation-independent external forces, e.g.
spherical shapes, to the case of generic body shapes subject to steady
aerodynamics.


title: Locally bounded perturbations and (odd) unbounded KK-theory

abstract:
  A regular symmetric operator on a Hilbert module is self-adjoint whenever
there exists a suitable approximate identity. We say an operator is 'locally
bounded' if the composition of the operator with each element in the
approximate identity is bounded. We prove that the perturbation of a regular
self-adjoint operator by a locally bounded symmetric operator is again regular
and self-adjoint. We use this result to show that the Kasparov class
represented by an unbounded Kasparov module is stable under locally bounded
perturbations. As an application, we show that we obtain a converse to the
'doubling up' procedure of odd unbounded Kasparov modules. Finally, we discuss
perturbations of unbounded Kasparov modules by unbounded multipliers. In
particular, we explicitly construct an unbounded multiplier such that (after
doubling up the module) the perturbed operator has compact resolvent.


title: The Joint Physics Analysis Center: Recent results

abstract:
  We review some of the recent achievements of the Joint Physics Analysis
Center, a theoretical collaboration with ties to experimental collaborations,
that aims to provide amplitudes suitable for the analysis of the current and
forthcoming experimental data on hadron physics. Since its foundation in 2013,
the group is focused on hadron spectroscopy in preparation for the forthcoming
high statistics and high precision experimental data from BELLEII, BESIII,
CLAS12, COMPASS, GlueX, LHCb and (hopefully) PANDA collaborations. So far, we
have developed amplitudes for $\pi N$ scattering, $\bar{K}N$ scattering, pion
and $J/\psi$ photoproduction, two kaon photoproduction and three-body decays of
light mesons ($\eta$, $\omega$, $\phi$). The codes for the amplitudes are
available to download from the group web page and can be straightforwardly
incorporated to the analysis of the experimental data.


title:
Multivariable Adaptive Harmonic Steady-State Control for Rejection of
  Sinusoidal Disturbances Acting on an Unknown System

abstract:
  This paper presents an adaptive harmonic steady-state (AHSS) controller,
which addresses the problem of rejecting sinusoids with known frequencies that
act on a completely unknown multi-input multi-output linear time-invariant
system. We analyze the stability and closed-loop performance of AHSS for
single-input single-output systems. In this case, we show that AHSS
asymptotically rejects disturbances.


title: Hurewicz fibrations in elementary toposes

abstract:
  We study formal counterparts of Hurewicz fibrations and related topological
notions in elementary toposes with NNO. The constructions are based on a
specific notion of interval and lead to a structure of category of fibrant
objects on toposes equipped with such a datum. We get in fact slightly more as
the building blocks are derived from a weak factorisation system.


title: On enumeration of tree-rooted planar cubic maps

abstract:
  We consider planar cubic maps, i.e. connected cubic graphs imbedded into
plane, with marked spanning tree and marked directed edge (not in this tree).
The number of such objects with $2n$ vertices is $C_{2n}\cdot C_{n+1}$, where
$C_k$ is $k$-th Catalan number.


title:
Observation of field emission from GeSn nanoparticles epitaxially grown
  on silicon nanopillar arrays

abstract:
  We apply molecular beam epitaxy to grow GeSn-nanoparticles on top of
Si-nanopillars patterned onto p-type Si wafers. We use X-ray photoelectron
spectroscopy to confirm a metallic behavior of the nanoparticle surface due to
partial Sn segregation as well as the presence of a superficial Ge oxide. We
report the observation of stable field emission current from the
GeSn-nanoparticles. We prove that field emission can be enhanced by preventing
GeSn nanoparticles oxidation or by breaking the oxide layer through electrical
stress. Finally, we show that GeSn/p-Si junctions have a rectifying behavior.


title: Lattice bosons with infinite range checkerboard interactions

abstract:
  Motivated by experiments performed by Landig et al. [Nature 532, 476-479], we
consider a two dimensional Bose gas in an optical lattice, trapped inside a
single mode superradiant Fabry Perot cavity. The cavity mediates infinite range
checkerboard interactions between the atoms, which produces competition between
Mott insulator, charge density wave, superfluid and supersolid phases. We
calculate the phase diagram of this Bose gas in a homogeneous system and in the
presence of a harmonic trap.


title:
Optimized plasma high harmonics generation from ultra-intense laser
  pulses

abstract:
  Plasma high harmonics generation from an extremely intense short-pulse laser
is explored by including the effects of ion motion, electron-ion collisions and
radiation reaction force in the plasma dynamics. The laser radiation pressure
induces plasma ion motion through the hole-boring effect resulting into the
frequency shifting and widening of the harmonic spectra. Classical radiation
reaction force slightly mitigates the frequency broadening caused by the ion
motion. Based on the results and physical considerations, parameter maps
highlighting optimum regions for generating a single intense attosecond pulse
and coherent XUV radiations are presented.


title: Optical response of correlated electron systems

abstract:
  Recent progress in experimental techniques has made it possible to extract
detailed information on dynamics of carriers in a correlated electron material
from its optical conductivity, $\sigma(\Omega, T)$. This review consists of
three parts, addressing the following three aspects of optical response: 1) the
role of momentum relaxation, 2) $\Omega/T$ scaling of the optical conductivity
of a Fermi-liquid metal, and 3) optical conductivity of non-Fermi-liquid
metals. In the first part (Sec. II), we analyze the interplay between the
contributions to the conductivity from normal and umklapp scattering. In the
second part (Secs. III and IV), we re-visit the Gurzhi formula for the optical
scattering rate, $1/\tau(\Omega,T)\propto\Omega^2+4\pi^2 T^2$, and show that a
factor of $4\pi^2$ is the manifestation of the "first-Matsubara-frequency
rule", which states that $1/\tau(\Omega,T)$ must vanish upon analytic
continuation to the first boson Matsubara frequency. However, recent
experiments show that the coefficient $b$ in the Gurzhi-like form,
$1/\tau(\Omega,T)\propto\Omega^2+b\pi^2 T^2$, differs significantly from $b=4$
in most of the cases. We suggest that the discrepancy may be due to the
presence of elastic scattering, which decreases the value of $b$ below $4$,
with $b=1$ corresponding to purely elastic scattering. In the third part (Sec.
V), we consider the optical conductivity of metals near quantum phase
transitions to nematic and spin-density-wave (SDW) states. In the last case, we
focus on "composite" scattering processes, which give rise to a
non-Fermi--liquid behavior of the optical conductivity:
$\sigma'(\Omega,T)\propto \Omega^{-1/3}$ at low frequencies and
$\sigma'(\Omega,T)\propto \Omega^{-1}$ at higher frequencies. We also discuss
$\Omega/T$ scaling and show that $\sigma'(\Omega,T)$ in the same model scales
in a non-Fermi-liquid way, as $T^{4/3}\Omega^{-5/3}$.


title: A note on the Survivable Network Design Problem

abstract:
  In this note we consider the survivable network design problem (SNDP) in
undirected graphs. We make two contributions. The first is a new counting
argument in the iterated rounding based 2-approximation for edge-connectivity
SNDP (EC-SNDP) originally due to Jain. The second is to make some additional
connections between hypergraphic version of SNDP introduced by Zhao, Nagamochi
and Ibaraki and edge and node-weighted versions of EC-SNDP and
element-connectivity SNDP (Elem-SNDP). One useful consequence of this
connection is a 2-approximation for Elem-SNDP that avoids the use of set-pair
based relaxation and analysis.


title:
Higher order mean curvatures of SAC half-lightlike submanifolds of
  indefinite almost contact manifolds

abstract:
  We introduce higher order mean curvatures of screen almost conformal (SAC)
half-lightlike submanifolds of indefinite contact manifolds, admitting a
semi-symmetric non-metric connection, and use them to generalize some known
results of [6]. Also, we derive a new set of integration formulae via the
divergence of some special vector fields tangent to this submanifold. Several
examples are also included to illustrate the main concepts.


title:
Fictitious magnetic field gradients in optical microtraps as an
  experimental tool for interrogating and manipulating cold atoms

abstract:
  Optical microtraps provide a strong spatial confinement for laser-cooled
atoms. They can, e.g., be realized with strongly focused trapping light beams
or the optical near fields of nano-scale waveguides and photonic
nanostructures. Atoms in such traps often experience strongly spatially varying
AC Stark shifts which are proportional to the magnetic quantum number of the
respective energy level. These inhomogeneous fictitious magnetic fields can
cause a displacement of the trapping potential that depends on the Zeeman
state. Hitherto, this effect was mainly perceived as detrimental. However, it
also provides a means to probe and to manipulate the motional state of the
atoms in the trap by driving transitions between Zeeman states. Furthermore, by
applying additional real or fictitious magnetic fields, the state-dependence of
the trapping potential can be controlled. Here, using laser-cooled atoms that
are confined in a nanofiber-based optical dipole trap, we employ this control
in order to tune the microwave coupling of motional quantum states. We record
corresponding microwave spectra which allow us to infer the trap parameters as
well as the temperature of the atoms. Finally, we reduce the mean number of
motional quanta in one spatial dimension to $\langle n\rangle=0.3 \pm 0.1$ by
microwave sideband cooling. Our work shows that the inherent fictitious
magnetic fields in optical microtraps expand the experimental toolbox for
interrogating and manipulating cold atoms.


title: Partial resolution by toroidal blow-ups

abstract:
  We answer a question of Keel: How much can one improve a non-toroidal ideal
sheaf by a sequence of toroidal blow-ups? Version2: Corollary 5 was proved
earlier by Tevelev and Ulirsch.


title: Topic Modelling and Event Identification from Twitter Textual Data

abstract:
  The tremendous growth of social media content on the Internet has inspired
the development of the text analytics to understand and solve real-life
problems. Leveraging statistical topic modelling helps researchers and
practitioners in better comprehension of textual content as well as provides
useful information for further analysis. Statistical topic modelling becomes
especially important when we work with large volumes of dynamic text, e.g.,
Facebook or Twitter datasets. In this study, we summarize the message content
of four data sets of Twitter messages relating to challenging social events in
Kenya. We use Latent Dirichlet Allocation (LDA) topic modelling to analyze the
content. Our study uses two evaluation measures, Normalized Mutual Information
(NMI) and topic coherence analysis, to select the best LDA models. The obtained
LDA results show that the tool can be effectively used to extract discussion
topics and summarize them for further manual analysis


title:
MOCCA-SURVEY Database I: Coalescing Binary Black Holes Originating From
  Globular Clusters

abstract:
  In this first of a series of papers, we utilize results for around two
thousand star cluster models simulated using the MOCCA code for star cluster
evolution (Survey Database I) to determine the astrophysical properties and
local merger rate densities for coalescing binary black holes (BBHs)
originating from globular clusters (GCs). We extracted information for all
coalescing BBHs that escape the cluster models and subsequently merge within a
Hubble time along with BBHs that are retained in our GC models and merge inside
the cluster via gravitational wave (GW) emission. By obtaining results from a
substantial number of realistic star cluster models that cover different
initial parameters, we have an extremely large statistical sample of BBHs with
stellar mass and massive stellar BH ($\lesssim 100M_{\odot}$) components that
merge within a Hubble time. Using this data, we estimate local merger rate
densities for these BBHs originating from GCs to be at least 5.4 ${\rm
Gpc}^{-3}\,{\rm yr}^{-1}$


title:
Correlations in Double Parton Distributions: Perturbative and
  Non-Perturbative effects

abstract:
  The correct description of Double Parton Scattering (DPS), which represents a
background in several channels for the search of new Physics at the LHC,
requires the knowledge of double parton distribution functions (dPDFs). These
quantities represent also a novel tool for the study of the three-dimensional
nucleon structure, complementary to the possibilities offered by
electromagnetic probes. In this paper we analyze dPDFs using Poincar\'e
covariant predictions obtained by using a Light-Front constituent quark model
proposed in a recent paper, and QCD evolution. We study to what extent
factorized expressions for dPDFs, which neglect, at least in part, two-parton
correlations, can be used. We show that they fail in reproducing the calculated
dPDFs, in particular in the valence region. Actually measurable processes at
existing facilities occur at low longitudinal momenta of the interacting
partons; to have contact with these processes we have analyzed correlations
between pairs of partons of different kind, finding that, in some cases, they
are strongly suppressed at low longitudinal momenta, while for other
distributions they can be sizeable. For example, the effect of gluon-gluon
correlations can be as large as 20 $\%$. We have shown that these behaviors can
be understood in terms of a delicate interference of non-perturbative
correlations, generated by the dynamics of the model, and perturbative ones,
generated by the model independent evolution procedure. Our analysis shows that
at LHC kinematics two-parton correlations can be relevant in DPS, and therefore
we address the possibility to study them experimentally.


title: Projective superflows. III. Finite subgroups of $U(2)$

abstract:
  Let $X\in\mathbb{R}^{n}$ or $\mathbb{C}^{n}$. For
$\phi:\mathbb{R}^{n}\mapsto\mathbb{R}^{n}$ (respectively,
$\phi:\mathbb{C}^{n}\mapsto\mathbb{C}^{n}$) and $t\in\mathbb{R}$ (respectively,
$\mathbb{C}$), we put $\phi^{t}=t^{-1}\phi(Xt)$. A projective flow is a
solution to the projective translation equation
$\phi^{t+s}=\phi^{t}\circ\phi^{s}$, $t,s\in\mathbb{R}$ or $\mathbb{C}$.
  The projective superflow is a projective flow with a rational vector field
which, among projective flows with a given symmetry, is, up to a homothety,
unique and optimal. In the first and the second part of this work we classified
real $2$ and $3-$dimensional supeflows over $\mathbb{R}$.
  In this third part we classify all $2-$dimensional complex superflows; that
is, whose group of symmetries are finite subgroups of $U(2)$. This includes
both irreducible and reducible superflows.


title:
Role of Intensive and Extensive Variables in a Soup of Firms in Economy
  to Address Long Run Prices and Aggregate Data

abstract:
  We review the production function and the hypothesis of equilibrium in the
neoclassical framework. We notify that in a soup of sectors in economy, while
capital and labor resemble extensive variables, wage and rate of return on
capital act as intensive variables. As a result, Baumol and Bowen's statement
of equal wages is inevitable from the thermodynamics point of view. We try to
see how aggregation can be performed concerning the extensive variables in a
soup of firms. We provide a toy model to perform aggregation for production and
the labor income as extensive quantities in a neoclassical framework.


title: Virtual pullbacks in $K$-theory

abstract:
  We consider virtual pullbacks in $K$-theory, and show that they are bivariant
classes and satisfy certain functoriality. As applications to $K$-theoretic
counting invariants, we include proofs of a virtual localization formula for
schemes and a degeneration formula in Donaldson-Thomas theory.


title: Magnetically self-regulated formation of early protoplanetary discs

abstract:
  The formation of protoplanetary discs during the collapse of molecular dense
cores is significantly influenced by angular momentum transport, notably by the
magnetic torque. In turn, the evolution of the magnetic field is determined by
dynamical processes and non-ideal MHD effects such as ambipolar diffusion.
Considering simple relations between various timescales characteristic of the
magnetized collapse, we derive an expression for the early disc radius, $ r
\simeq 18 \, {\rm AU} \, \left({\eta_{\rm AD} / 0.1 \, {\rm s}} \right)^{2/9}
\left({B_z / 0.1\, {\rm G}} \right) ^{-4/9} \left({M / 0.1 \msol} \right)
^{1/3},$ where $M$ is the total disc plus protostar mass, $\eta_\mathrm{AD}$ is
the ambipolar diffusion coefficient and $B_z$ is the magnetic field in the
inner part of the core. This is about significantly smaller than the discs that
would form if angular momentum was conserved.
  The analytical predictions are confronted against a large sample of 3D,
non-ideal MHD collapse calculations covering variations of a factor 100 in core
mass, a factor 10 in the level of turbulence, a factor 5 in rotation, and
magnetic mass-to-flux over critical mass-to-flux ratios 2 and 5. The disc
radius estimates are found to agree with the numerical simulations within less
than a factor 2.
  A striking prediction of our analysis is the weak dependence of circumstellar
disc radii upon the various relevant quantities, suggesting weak variations
among class-0 disc sizes. In some cases, we note the onset of large spiral arms
beyond this radius.


title:
On the use of the incompressibility condition in the Euler and
  Navier-Stokes equations

abstract:
  The Euler and Navier-Stokes equations both belong to a closed system of three
transport equations, describing the particle number density N, the macroscopic
velocity v and the temperature T. These sytems are complete, leaving no room
for any additional equation. Nonetheless, it is common practice in parts of the
literature to replace the thermal equation by the incompressibility condition
div v = 0, motivated by the wish to obtain simpler equations. It is shown that
this procedure is physically inconsistent in several ways, with the consequence
that incompressibility is not a property that can be enforced by an external
condition. Incompressible behaviour, if existing, will have to follow
self-consistently from the full set of transport equations.


title:
Experimental validation of volume-based comparison for double-McCormick
  relaxations

abstract:
  Volume is a natural geometric measure for comparing polyhedral relaxations of
non-convex sets. Speakman and Lee gave volume formulae for comparing
relaxations of trilinear monomials, quantifying the strength of various natural
relaxations. Their work was motivated by the spatial branch-and-bound algorithm
for factorable mathematical-programming formulations. They mathematically
analyzed an important choice that needs to be made whenever three or more terms
are multiplied in a formulation. We experimentally substantiate the relevance
of their main results to the practice of global optimization, by applying it to
difficult box cubic problems (boxcup). In doing so, we find that, using their
volume formulae, we can accurately predict the quality of a relaxation for
boxcups based on the (box) parameters defining the feasible region.


title:
Temperature dependence of the spin Hall angle and switching current in
  the nc-W(O)/CoFeB/MgO system with perpendicular magnetic anisotropy

abstract:
  We investigated the temperature dependence of the switching current for a
perpendicularly magnetized CoFeB film deposited on a nanocrystalline tungsten
film with large oxygen content: nc-W(O). The spin Hall angle
$|\Theta_\mathrm{SH}| \approx 0.22$ is independent of temperature, whereas the
switching current increases strongly at low temperature. We show that the
nc-W(O) is insensitive to annealing. It thus can be a good choice for the
integration of spin Hall driven writing of information in magnetic memory or
logic devices that require a high-temperature annealing process during
fabrication.


title:
Implications of a Electroweak Triplet Scalar Leptoquark on the
  Ultra-High Energy Neutrino Events at IceCube

abstract:
  We study the production of scalar leptoquarks at IceCube, in particular, a
particle transforming as a triplet under the weak interaction. The existence of
electroweak-triplet scalars is highly motivated by models of grand unification
and also within radiative seesaw models for neutrino mass generation. In our
framework, we extend the Standard Model by a single colored electroweak-triplet
scalar leptoquark and analyze its implications on the excess of ultra-high
energy neutrino events observed by the IceCube collaboration. We consider only
couplings between the leptoquark to first generation leptons and quarks and
carry out a statistical analysis to determine the parameters that best describe
the IceCube data as well as set $95\%$ CL upper bounds. We analyze whether this
study is still consistent with most up-to-date LHC data and various low energy
observables.


title: Border Ranks of Monomials

abstract:
  Young flattenings, introduced by Landsberg and Ottaviani, give determinantal
equations for secant varieties and their non-vanishing provides lower bounds
for border ranks of tensors and in particular polynomials. We study
monomial-optimal shapes for Young flattenings, which exhibit the limits of the
Young flattening method. In particular, they provide the best possible lower
bound for large classes of monomials including all monomials up to degree 6,
monomials in 3 variables, and any power of the product of variables. On the
other hand, for degree 7 and higher there are monomials for which no Young
flattening can give a lower bound that matches the conjecturally tight upper
bound of Landsberg and Teitler.


title:
Tight lower bounds for connected queen domination problems on the
  chessboard

abstract:
  1. We first show a lower bound of 2N/3-1 for the connected minimum queen
domination (or cover) problem on the NXN chessboard - the upper bound is only 2
higher at most and is easy to show. 2. We then define the k-colored connected
minimum queen domination, and extend the above proof to show a lower bound of
(2 N - k - 2)/3, where the parameter k can be increased to get decreasing lower
bounds LB(N, k) until one reaches the simple domination lower bound of floor
N/2. 3. We also discuss extensions of the connected domination problem and
additional directions.


title:
Hawking versus Unruh effects, or the difficulty of slowly crossing a
  black hole horizon

abstract:
  When analyzing the perception of Hawking radiation by different observers,
the Hawking effect becomes mixed with the Unruh effect. The separation of both
effects is not always clear in the literature. Here we propose an
inconsistency-free interpretation of what constitutes a Hawking effect and what
an Unruh effect. An appropriate interpretation is important in order to
elucidate what sort of effects a detector might experience depending on its
trajectory and the state of the quantum field. Under simplifying assumptions we
introduce an analytic formula that separates these two effects. Armed with the
previous interpretation we argue that for a free-falling detector to cross the
horizon without experiencing high-energy effects, it is necessary that the
horizon crossing is not attempted at low velocities.


title: Designing Modular Software: A Case Study in Introductory Statistics

abstract:
  Modular programming is a development paradigm that emphasizes self-contained,
flexible, and independent pieces of functionality. This practice allows new
features to be seamlessly added when desired, and unwanted features to be
removed, thus simplifying the user-facing view of the software. The recent rise
of web-based software applications has presented new challenges for designing
an extensible, modular software system. In this paper, we outline a framework
for designing such a system, with a focus on reproducibility of the results. We
present as a case study a Shiny-based web application called intRo, that allows
the user to perform basic data analyses and statistical routines. Finally, we
highlight some challenges we encountered, and how to address them, when
combining modular programming concepts with reactive programming as used by
Shiny.


title:
Pre-proceedings of the 26th International Symposium on Logic-Based
  Program Synthesis and Transformation (LOPSTR 2016)

abstract:
  This volume constitutes the pre-proceedings of the 26th International
Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2016),
held on 6-8th September 2016 in Edinburgh, Scotland UK, and co-located with the
18th International Symposium on Principles and Practice of Declarative
Programming (PPDP 2016) and the 23rd Static Analysis Symposium (SAS 2016).
After discussion at the symposium papers will go through a second round of
refereeing and selection for the formal proceedings.


title:
Stabilized density gradient theory algorithm for modeling interfacial
  properties of pure and mixed systems

abstract:
  Density gradient theory (DGT) allows fast and accurate determination of
surface tension and density profile through a phase interface. Several
algorithms have been developed to apply this theory in practical calculations.
While the conventional algorithm requires a reference substance of the system,
a modified "stabilized density gradient theory" (SDGT) algorithm is introduced
in our work to solve DGT equations for multiphase pure and mixed systems. This
algorithm makes it possible to calculate interfacial properties accurately at
any domain size larger than the interface thickness without choosing a
reference substance or assuming the functional form of the density profile. As
part of DGT inputs, the perturbed chain statistical associating fluid theory
(PC-SAFT) equation of state (EoS) was employed for the first time with the SDGT
algorithm. PC-SAFT has excellent performance in predicting liquid phase
properties as well as phase behaviors. The SDGT algorithm with the PC-SAFT EoS
was tested and compared with experimental data for several systems. Numerical
stability analyses were also included in each calculation to verify the
reliability of this approach for future applications.


title:
Geostrophic wind induced by latitudinal variation in gravitational
  acceleration on oblate planets

abstract:
  The population of known extrasolar planets includes giant and terrestrial
planets that closely orbit their host star. Such planets experience significant
tidal distortions that can force the planet into synchronous rotation. The
combined effects of tidal deformation and centripetal acceleration induces
significant asphericity in the shape of these planets, compared to the mild
oblateness of Earth, with maximum gravitational acceleration at the poles. Here
we show that this latitudinal variation in gravitational acceleration is
relevant for modeling the climate of oblate planets including Jovian planets
within the solar system, closely-orbiting hot Jupiters, and planets within the
habitable zone of white dwarfs. We compare first- and third-order
approximations for gravitational acceleration on an oblate spheroid and
calculate the geostrophic wind that would result from this asphericity on a
range of solar system planets and exoplanets. Third-order variations in
gravitational acceleration are negligible for Earth but become significant for
Jupiter, Saturn, and Jovian exoplanets. This latitudinal variation in
gravitational acceleration can be measured remotely, and the formalism
presented here can be implemented for use in general circulation climate
modeling studies of exoplanet atmospheres.


title: $P$-wave coupled channel effects in electron-positron annihilation

abstract:
  $P$-wave coupled channel effects arising from the $D\bar{D}$,
$D\bar{D}^*+c.c.$, and $D^*\bar{D}^*$ thresholds in $e^+e^-$ annihilations are
systematically studied. We provide an exploratory study by solving the
Lippmann-Schwinger equation with short-ranged contact potentials obtained in
the heavy quark limit. These contact potentials can be extracted from the
$P$-wave interactions in the $e^+e^-$ annihilations, and then be employed to
investigate possible isosinglet $P$-wave hadronic molecules. In particular,
such an investigation may provide information about exotic candidates with
quantum numbers $J^{PC}=1^{-+}$. In the mass region of the $D\bar{D}$,
$D\bar{D}^*+c.c.$, and $D^*\bar{D}^*$ thresholds, there are two quark model
bare states, i.e. the $\psi(3770)$ and $\psi(4040)$, which are assigned as
$(1^3D_1)$ and $(3^1S_1)$ states, respectively. By an overall fit of the cross
sections of $e^+e^-\to D\bar{D}$, $D\bar{D}^*+c.c.$, $D^*\bar{D}^*$, we
determine the physical coupling constants to each channel and extract the pole
positions of the $\psi(3770)$ and $\psi(4040)$. The deviation of the ratios
from that in the heavy quark spin symmetry (HQSS) limit reflects the HQSS
breaking effect due to the mass splitting between the $D$ and the $D^*$.
Besides the two poles, we also find a pole a few MeV above the
$D\bar{D}^*+c.c.$ threshold which can be related to the so-called $G(3900)$
observed earlier by BABAR and Belle. This scenario can be further scrutinized
by measuring the angular distribution in the $D^*\bar{D}^*$ channel with high
luminosity experiments.


title: Towards the (Mexican) discovery of second class currents at Belle-II

abstract:
  Within the SM, the yet unmeasured $\tau^-\to\pi^-\eta^{(\prime)}\nu_\tau$
decays are predicted as a suppressed, isospin-violating effect with branching
ratios $\lesssim\mathcal{O}(10^{-5})$. However, they can also proceed through
other mechanisms (such as charged Higgs exchange) at comparable rates. This has
motivated several studies of the corresponding QCD predictions for these second
class current processes. In this contribution we discuss the prospects for the
discovery of these decays at Belle-II emphasizing the Mexican involvement in
this project. Our branching ratio prediction $\sim1.7\cdot10^{-5}$ (decay
channel with an $\eta$ meson) is well within the reach of Belle-II. The
branching fraction for the decay channel with an $\eta^\prime$ meson is
expected to be between one and two orders of magnitude more suppressed.


title:
Further results on the uniqueness of meromorphic functions and their
  derivative counterpart sharing one or two sets

abstract:
  In this paper we prove a number of results concerning uniqueness of a
meromorphic function as well as its derivative sharing one or two sets. In
particular, we deal with the specific question raised in [18], [19], [20] and
ultimately improve the result of Banerjee-Bhattacharjee [4].


title: Gravity wave and model-independent axion

abstract:
  In this short comment, we notice that the model-independent axion
contribution to the graviton mass at just outside the Schwarzschild radius is
completely negligible in GW150914. The model-independent axion contribution to
the graviton mass at the order $10^{-22}\,$eV might be possible for merger of
black holes of mass of order $2\times 10^{14}\,$kg.


title:
Growth of perturbations in nonlocal gravity with non-$\Lambda$CDM
  background

abstract:
  We re-analyze the nonlocal gravity model of Deser and Woodard which was
proposed to account for the current phase of cosmic acceleration. We show that
the growth of perturbations predicted by this nonlocal gravity model when its
background evolution is fixed by some particular non-$\Lambda$CDM models can be
substantially lower than when its background is fixed by $\Lambda$CDM. This can
be seen when we consider the background expansion by a dark energy model with a
slightly less negative equation of state with respect to cosmological constant.
Our results hints towards a fact that the choice of the background expansion
can play a crucial role how this nonlocal gravity model can fit the growth
history data. While the growth data might show better consistency to GR models
(among the background models we studied so far), it seems the nonlocal gravity
model studied in this work is able to show comparable consistency to the growth
data as well. Showing this consistency can be considered as a significant
result since this model can stand as a distinguishable alternative to the
standard model of cosmology.


title:
Analogues of glacial valley profiles in particle mechanics and in
  cosmology

abstract:
  An ordinary differential equation describing the transverse profiles of
U-shaped glacial valleys, derived with a variational principle, has two formal
analogies which we analyze. First, an analogy with point particle mechanics
completes the description of the solutions. Second, an analogy with the
Friedmann equation of relativistic cosmology shows that the analogue of a
glacial valley profile is a universe with a future singularity but respecting
the weak energy condition. The equation unveils also a Big Freeze singularity,
which was not observed before for positive curvature index.


title: On the Generalizations of Br\"{u}ck Conjecture

abstract:
  We obtain similar types of conclusions as that of Br\"{u}ck \cite{3} for two
differential polynomials which in turn radically improve and generalize several
existing results. Moreover a number of examples have been exhibited to justify
the necessity or sharpness of some conditions used in the paper. At last we
pose an open problem for future research.


title: Self-amplifying Hawking radiation and its background: a numerical study

abstract:
  We numerically study an analogue black hole with two horizons with similar
parameters to a recent experiment. We find that the Hawking radiation exists on
a background which contains a density oscillation, a zero-frequency ripple. The
Hawking radiation evolves from spontaneous to self-amplifying, while the
background ripple grows steadily with no qualitative change. It is seen that
the self-amplifying Hawking radiation has a non-zero frequency. The background
ripple appears even before the inner horizon is created, in contrast to
predictions. This work is in agreement with the recent observation of
self-amplifying Hawking radiation, and explains some of the features seen. In
contrast to recent works, our study differentiates between the Hawking
radiation observed, and the evolution of the background.


title:
The monotonicity of an entropy like energy for the heat equation on a
  quaternionic contact and CR manifolds

abstract:
  A proof of the monotonicity of an entropy like energy for the heat equation
on a quaternionic contact and CR manifolds is proven


title:
A Stackelberg Game Perspective on the Conflict Between Machine Learning
  and Data Obfuscation

abstract:
  Data is the new oil; this refrain is repeated extensively in the age of
internet tracking, machine learning, and data analytics. As data collection
becomes more personal and pervasive, however, public pressure is mounting for
privacy protection. In this atmosphere, developers have created applications to
add noise to user attributes visible to tracking algorithms. This creates a
strategic interaction between trackers and users when incentives to maintain
privacy and improve accuracy are misaligned. In this paper, we conceptualize
this conflict through an N+1-player, augmented Stackelberg game. First a
machine learner declares a privacy protection level, and then users respond by
choosing their own perturbation amounts. We use the general frameworks of
differential privacy and empirical risk minimization to quantify the utility
components due to privacy and accuracy, respectively. In equilibrium, each user
perturbs her data independently, which leads to a high net loss in accuracy. To
remedy this scenario, we show that the learner improves his utility by
proactively perturbing the data himself. While other work in this area has
studied privacy markets and mechanism design for truthful reporting of user
information, we take a different viewpoint by considering both user and learner
perturbation.


title:
On the channel width-dependence of the thermal conductivity in
  ultra-narrow graphene nanoribbons

abstract:
  The thermal conductivity of low-dimensional materials and graphene
nanoribbons in particular, is limited by the strength of line-edge-roughness
scattering. One way to characterize the roughness strength is the dependency of
the thermal conductivity on the channel width in the form W^{\beta}. Although
in the case of electronic transport this dependency is very well studied,
resulting in W^6 for nanowires and quantum wells and W^4 for nanoribbons, in
the case of phonon transport it is not yet clear what this dependence is. In
this work, using lattice dynamics and Non-Equilibrium Greens Function
simulations, we examine the width dependence of the thermal conductivity of
ultra-narrow graphene nanoribbons under the influence of line edge-roughness.
We show that the exponent {\beta} is in fact not a single well-defined number,
but it is different for different parts of the phonon spectrum depending on
whether phonon transport is ballistic, diffusive, or localized. The exponent
{\beta} takes values {\beta} < 1 for semi-ballistic phonon transport, values
{\beta} >> than 1 for sub-diffusive or localized phonons, and {\beta} = 1 only
in the case where the transport is diffusive. The overall W^{\beta} dependence
of the thermal conductivity is determined by the width-dependence of the
dominant phonon modes (usually the acoustic ones). We show that due to the long
phonon mean-free-paths, the width-dependence of thermal conductivity becomes a
channel length dependent property, because the channel length determines
whether transport is ballistic, diffusive, or localized.


title:
The effects of Ekman pumping on quasi-geostrophic Rayleigh-Benard
  convection

abstract:
  Numerical simulations of 3D, rapidly rotating Rayleigh-Benard convection are
performed using an asymptotic quasi-geostrophic model that incorporates the
effects of no-slip boundaries through (i) parameterized Ekman pumping boundary
conditions, and (ii) a thermal wind boundary layer that regularizes the
enhanced thermal fluctuations induced by pumping. The fidelity of the model,
obtained by an asymptotic reduction of the Navier-Stokes equations that
implicitly enforces a pointwise geostrophic balance, is explored for the first
time by comparisons of simulations against the findings of direct numerical
simulations and laboratory experiments. Results from these methods have
established Ekman pumping as the mechanism responsible for significantly
enhancing the vertical heat transport. This asymptotic model demonstrates
excellent agreement over a range of thermal forcing for Pr ~1 when compared
with results from experiments and DNS at maximal values of their attainable
rotation rates, as measured by the Ekman number (E ~ 10^{-7}); good qualitative
agreement is achieved for Pr > 1. Similar to studies with stress-free
boundaries, four spatially distinct flow morphologies exists. Despite the
presence of frictional drag at the upper and/or lower boundaries, a strong
non-local inverse cascade of barotropic (i.e., depth-independent) kinetic
energy persists in the final regime of geostrophic turbulence and is dominant
at large scales. For mixed no-slip/stress-free and no-slip/no-slip boundaries,
Ekman friction is found to attenuate the efficiency of the upscale energy
transport and, unlike the case of stress-free boundaries, rapidly saturates the
barotropic kinetic energy. For no-slip/no-slip boundaries, Ekman friction is
strong enough to prevent the development of a coherent dipole vortex
condensate. Instead vortex pairs are found to be intermittent, varying in both
time and strength.


title:
Sampling Requirements and Accelerated Schemes for Sparse Linear
  Regression with Orthogonal Least-Squares

abstract:
  We study the problem of inferring a sparse vector from random linear
combinations of its components. We propose the Accelerated Orthogonal
Least-Squares (AOLS) algorithm that improves performance of the well-known
Orthogonal Least-Squares (OLS) algorithm while requiring significantly lower
computational costs. While OLS greedily selects columns of the coefficient
matrix that correspond to non-zero components of the sparse vector, AOLS
employs a novel computationally efficient procedure that speeds up the search
by anticipating future selections via choosing $L$ columns in each step, where
$L$ is an adjustable hyper-parameter. We analyze the performance of AOLS and
establish lower bounds on the probability of exact recovery for both noiseless
and noisy random linear measurements. In the noiseless scenario, it is shown
that when the coefficients are samples from a Gaussian distribution, AOLS with
high probability recovers a $k$-sparse $m$-dimensional sparse vector using
${\cal O}(k\log \frac{m}{k+L-1})$ measurements. Similar result is established
for the bounded-noise scenario where an additional condition on the smallest
nonzero element of the unknown vector is required. The asymptotic sampling
complexity of AOLS is lower than the asymptotic sampling complexity of the
existing sparse reconstruction algorithms. In simulations, AOLS is compared to
state-of-the-art sparse recovery techniques and shown to provide better
performance in terms of accuracy, running time, or both. Finally, we consider
an application of AOLS to clustering high-dimensional data lying on the union
of low-dimensional subspaces and demonstrate its superiority over existing
methods.


title:
A time of ruin constrained optimal dividend problem for spectrally
  one-sided L\'evy processes

abstract:
  We introduce a longevity feature to the classical optimal dividend problem by
adding a constraint on the time of ruin of the firm. We extend the results in
\cite{HJ15}, now in context of one-sided L\'evy risk models. We consider de
Finetti's problem in both scenarios with and without fix transaction costs,
e.g. taxes. We also study the constrained analog to the so called Dual model.
To characterize the solution to the aforementioned models we introduce the dual
problem and show that the complementary slackness conditions are satisfied and
therefore there is no duality gap. As a consequence the optimal value function
can be obtained as the pointwise infimum of auxiliary value functions indexed
by Lagrange multipliers. Finally, we illustrate our findings with a series of
numerical examples.


title: Scattering of biflagellate microswimmers from surfaces

abstract:
  We use a three-bead-spring model to investigate the dynamics of bi-flagellate
micro-swimmers near a surface. While the primary dynamics and scattering are
governed by geometric-dependent direct contact, the fluid flows generated by
the swimmer locomotion are important in orienting it toward or away from the
surface. Flagellar noise and in particular cell spinning about the main axis
help a surface-trapped swimmer escape, whereas the time a swimmer spends at the
surface depends on the incident angle. The dynamics results from a nuanced
interplay of direct collisions, hydrodynamics, noise and the swimmer geometry.
We show that to correctly capture the dynamics of a biflagellate swimmer,
minimal models need to resolve the shape asymmetry.


title:
First Detection of Chromospheric Magnetic Field Changes During an
  X1-Flare

abstract:
  Stepwise changes of the photospheric magnetic field, which often becomes more
horizontal, have been observed during many flares. Previous interpretations
include coronal loops that contract and it has been speculated that such jerks
could be responsible for sunquakes. Here we report the detection of stepwise
chromospheric line-of-sight magnetic field (B$_{\rm LOS}$) changes obtained
through spectropolarimetry of Ca II 8542 \AA\ with DST/IBIS during the X1-flare
SOL20140329T17:48. They are stronger ($<$640 Mx cm$^{-2}$) and appear in larger
areas than their photospheric counterparts ($<$320 Mx cm$^{-2}$). The absolute
value of B$_{\rm LOS}$ more often decreases than increases. Photospheric
changes are predominantly located near a polarity inversion line, chromospheric
changes near footpoints of loops. The locations of changes are near, but not
exactly co-spatial to hard X-ray (HXR) emission and neither to enhanced
continuum emission, nor a small sunquake. Enhanced chromospheric and coronal
emission is observed in nearly all locations that exhibit changes of B$_{\rm
LOS}$, but the emission also occurs in many locations without any B$_{\rm LOS}$
changes. Photospheric and chromospheric changes of B$_{\rm LOS}$ show
differences in timing, sign, and size and seem independent of each other. A
simple model of contracting loops yields changes of opposite sign to those
observed. An explanation for this discrepancy could be increasing loop sizes or
loops that untwist in a certain direction during the flare. It is yet unclear
which processes are responsible for the observed changes, their timing, size
and locations, especially considering the incoherence between photosphere and
chromosphere.


title:
Exact Exchange-Correlation Functional for the Infinitely Stretched
  Hydrogen Molecule

abstract:
  The exchange-correlation hole density of the infinitely stretched
(dissociated) hydrogen molecule can be cast into a closed analytical form by
using its exact wave function. This permits to obtain an explicit
exchange-correlation energy functional of the electron density which allows for
its functional derivation to yield the corresponding Kohh-Sham effective
exchange-correlation potential. We have shown that this exchange-correlation
functional is exact for the dissociated hydrogen molecule, yields its
dissociation energy correctly, and its corresponding exchange-correlation
potential has the correct $-1/r$ asymptotic behavior.


title: Sparse recovery via Orthogonal Least-Squares under presence of Noise

abstract:
  We consider the Orthogonal Least-Squares (OLS) algorithm for the recovery of
a $m$-dimensional $k$-sparse signal from a low number of noisy linear
measurements. The Exact Recovery Condition (ERC) in bounded noisy scenario is
established for OLS under certain condition on nonzero elements of the signal.
The new result also improves the existing guarantees for Orthogonal Matching
Pursuit (OMP) algorithm. In addition, This framework is employed to provide
probabilistic guarantees for the case that the coefficient matrix is drawn at
random according to Gaussian or Bernoulli distribution where we exploit some
concentration properties. It is shown that under certain conditions, OLS
recovers the true support in $k$ iterations with high probability. This in turn
demonstrates that ${\cal O}\left(k\log m\right)$ measurements is sufficient for
exact recovery of sparse signals via OLS.


title: On gravitational and thermal corrections to vacuum decay

abstract:
  We reconsider gravitational corrections to vacuum decay, confirming and
simplifying earlier results and extending them by allowing for a non-minimal
coupling of the Higgs to gravity. We find that leading-order gravitational
corrections suppress the vacuum decay rate. Furthermore, we compute minor
corrections to thermal vacuum decay in the SM by adding one-loop contributions
to the Higgs kinetic term, two-loop contributions to the Higgs potential and
allowing for time-dependent bounces.


title: Constraints on new physics from radiative $B$ decays

abstract:
  A new phase for the measurements of radiative decay modes in $b \to s$
transitions has started with new measurements of exclusive modes by LHCb and
with Belle-II showing distinctive promises in both inclusive and exclusive
channels. After critically reviewing the hadronic uncertainties in exclusive
radiative decays, we analyze the impact of recent measurements of the branching
ratio and mass-eigenstate rate asymmetry in $B_s\to\phi\gamma$ and of the
angular distribution of $B\to K^*e^+e^-$ at low $q^2$ on new physics in the
$b\to s\gamma$ transition.


title: Symmetry-preserving numerical schemes

abstract:
  In these lectures we review two procedures for constructing finite difference
numerical schemes that preserve symmetries of differential equations. The first
approach is based on Lie's infinitesimal symmetry generators, while the second
method uses the novel theory of equivariant moving frames. The advantages of
both techniques are discussed and illustrated with the Schwarzian differential
equation, the Korteweg-de Vries equation and Burgers' equation. Numerical
simulations are presented and innovative techniques for obtaining better
invariant numerical schemes are introduced. New research directions and open
problems are indicated at the end of these notes.


title:
On Functions Whose Mean Value Abscissas Are Midpoints, with Connections
  to Harmonic Functions

abstract:
  We investigate functions with the property that for every interval, the slope
at the midpoint of the interval is the same as the average slope. More
generally, we find functions whose average slopes over intervals are given by
the slope at a weighted average of the endpoints of those intervals. This is
equivalent to finding functions satisfying a weighted mean value property. In
the course of our exploration, we find connections to harmonic functions that
prompt us to explore multivariable analogues and the existence of "weighted
harmonic functions."


title:
Fermi and Coulomb correlation effects upon the interacting quantum atoms
  energy partition

abstract:
  The Interacting Quantum Atoms (IQA) electronic energy partition is an
important method in the field of quantum chemical topology which has given
important insights of different systems and processes in physical chemistry.
There have been several attempts to include Electron Correlation (EC) in the
IQA approach, for example, through DFT and Hartree-Fock/Coupled-Cluster (HF/CC)
transition densities. This work addresses the separation of EC in Fermi and
Coulomb correlation and its effect upon the IQA analysis by taking into account
spin-dependent one- and two-electron matrices $D^{\mathrm{HF/CC}}_{p\sigma q
\sigma}$ and $d^{\mathrm{HF/CC}}_{p\sigma q\sigma r\tau s\tau}$ wherein
$\sigma$ and $\tau$ represent either of the $\alpha$ and $\beta$ spin
projections. We illustrate this approach by considering BeH$_2$,BH, CN$^-$, HF,
LiF, NO$^+$, LiH, H$_2$O$\cdots$H$_2$O and C$_2$H$_2$, which comprise non-polar
covalent, polar covalent, ionic and hydrogen bonded systems. The same and
different spin contributions to ($i$) the net, interaction and
exchange-correlation IQA energy components and ($ii$) delocalisation indices
defined in the quantum theory of atoms in molecules are carefully examined and
discussed. Overall, we expect that this kind of analysis will yield important
insights about Fermi and Coulomb correlation in covalent bonding,
intermolecular interactions and electron delocalisation in physical chemistry.


title:
Note on "Quantum superconducting criticality in graphene and topological
  insulators"

abstract:
  We correct our previous conclusion regarding the fate of a charged quantum
critical point across the superconducting transition for two dimensional
massless Dirac fermion. Within the leading order $\epsilon$ expansion, we now
find that the requisite number of four-component Dirac fermion flavors ($N_f$)
for the continuous phase transition through a charged critical point is
$N_f>18.2699$. For $N_f\geq1/2$, the critical number of bosonic flavors for
this transition is significantly reduced as compared to the value determined in
the absence of the Dirac fermions in the theory.


title:
Field Effect Optoelectronic Modulation of Quantum-Confined Carriers in
  Black Phosphorus

abstract:
  We report measurements of the infrared optical response of thin black
phosphorus under field-effect modulation. We interpret the observed spectral
changes as a combination of an ambipolar Burstein-Moss (BM) shift of the
absorption edge due to band-filling under gate control, and a quantum confined
Franz-Keldysh (QCFK) effect, phenomena which have been proposed theoretically
to occur for black phosphorus under an applied electric field. Distinct optical
responses are observed depending on the flake thickness and starting carrier
concentration. Transmission extinction modulation amplitudes of more than two
percent are observed, suggesting the potential for use of black phosphorus as
an active material in mid-infrared optoelectronic modulator applications.


title:
Influence of the Constant Electric Field on the Mutual Rectification of
  the Electromagnetic Waves in Graphene Superlattice

abstract:
  In tight binding approximation the explicit form of the electron energy in
graphene superlattice was derived. The possibility of propagation of the
cnoidal waves in graphene superlattice was discussed. The direct current
induced perpendicularly to the superlattice axis by cnoidal and sinusoidal
electromagnetic waves under the presence of longitudinal constant electric
field was calculated. Such direct current was shown to change its direction
when the intensity of longitudinal electric field changes its absolute value.


title: Lattice methods and effective field theory

abstract:
  Lattice field theory is a non-perturbative tool for studying properties of
strongly interacting field theories, which is particularly amenable to
numerical calculations and has quantifiable systematic errors. In these
lectures we apply these techniques to nuclear Effective Field Theory (EFT), a
non-relativistic theory for nuclei involving the nucleons as the basic degrees
of freedom. The lattice formulation of [1,2] for so-called pionless EFT is
discussed in detail, with portions of code included to aid the reader in code
development. Systematic and statistical uncertainties of these methods are
discussed at length, and extensions beyond pionless EFT are introduced in the
final Section.


title:
The KSBA compactification of the moduli space of $D_{1,6}$-polarized
  Enriques surfaces

abstract:
  We describe a compactification by stable pairs (also known as KSBA
compactification) of the $4$-dimensional family of Enriques surfaces which
arise as the $\mathbb{Z}_2^2$-covers of the blow up of $\mathbb{P}^2$ at three
general points branched along a configuration of three pairs of lines. Up to a
finite group action, we show that this compactification is isomorphic to the
toric variety associated to the secondary polytope of the unit cube. We relate
the KSBA compactification considered to the Baily-Borel compactification of the
same family of Enriques surfaces. Part of the KSBA boundary has a toroidal
behavior, another part is isomorphic to the Baily-Borel compactification, and
what remains is a mixture of these two. We relate the stable pair
compactification studied here with Looijenga's semitoric compactifications.


title: Semantic Code Browsing

abstract:
  Programmers currently enjoy access to a very high number of code repositories
and libraries of ever increasing size. The ensuing potential for reuse is
however hampered by the fact that searching within all this code becomes an
increasingly difficult task. Most code search engines are based on syntactic
techniques such as signature matching or keyword extraction. However, these
techniques are inaccurate (because they basically rely on documentation) and at
the same time do not offer very expressive code query languages. We propose a
novel approach that focuses on querying for semantic characteristics of code
obtained automatically from the code itself. Program units are pre-processed
using static analysis techniques, based on abstract interpretation, obtaining
safe semantic approximations. A novel, assertion-based code query language is
used to express desired semantic characteristics of the code as partial
specifications. Relevant code is found by comparing such partial specifications
with the inferred semantics for program elements. Our approach is fully
automatic and does not rely on user annotations or documentation. It is more
powerful and flexible than signature matching because it is parametric on the
abstract domain and properties, and does not require type definitions. Also, it
reasons with relations between properties, such as implication and abstraction,
rather than just equality. It is also more resilient to syntactic code
differences. We describe the approach and report on a prototype implementation
within the Ciao system.
  Under consideration for acceptance in TPLP.


title: Q-deformed Painleve tau function and q-deformed conformal blocks

abstract:
  We propose $q$-deformation of the Gamayun-Iorgov-Lisovyy formula for
Painlev\'e $\tau$ function. Namely we propose formula for $\tau$ function for
$q$-difference Painlev\'e equation corresponding to $A_7^{(1)}{}'$ surface (and
$A_1^{(1)}$ symmetry) in Sakai's classification. In this formula $\tau$
function equals the series of $q$-Virasoro Whittaker conformal blocks
(equivalently Nekrasov partition functions for pure $SU(2)$ 5d theory).


title: A Geometric Multigrid Preconditioning Strategy for DPG System Matrices

abstract:
  The discontinuous Petrov-Galerkin (DPG) methodology of Demkowicz and
Gopalakrishnan [15,17] guarantees the optimality of the solution in an energy
norm, and provides several features facilitating adaptive schemes. A key
question that has not yet been answered in general - though there are some
results for Poisson, e.g. - is how best to precondition the DPG system matrix,
so that iterative solvers may be used to allow solution of large-scale
problems.
  In this paper, we detail a strategy for preconditioning the DPG system matrix
using geometric multigrid which we have implemented as part of Camellia [26],
and demonstrate through numerical experiments its effectiveness in the context
of several variational formulations. We observe that in some of our
experiments, the behavior of the preconditioner is closely tied to the discrete
test space enrichment.
  We include experiments involving adaptive meshes with hanging nodes for
lid-driven cavity flow, demonstrating that the preconditioners can be applied
in the context of challenging problems. We also include a scalability study
demonstrating that the approach - and our implementation - scales well to many
MPI ranks.


title: Backlund transformation of Painleve III($D_8$) tau function

abstract:
  We study explicit formula (suggested by Gamayun, Iorgov, Lisovyy) for
Painlev\'e III($D_8$) $\tau$ function in terms of Virasoro conformal blocks
with central charge $1$. The Painlev\'e equation has two types of bilinear
forms, we call them Toda-like and Okamoto-like. We obtain these equations from
the representation theory using an embedding of a direct sum of two Virasoro
algebra in a certain superalgebra. These two types of bilinear forms correspond
to Neveu-Schwarz sector and Ramond sector of this algebra. We also obtain
$\tau$ functions of algebraic solutions of Painlev\'e III($D_8$) from the
special representations of the Virasoro algebra of highest weight $(n+1/4)^2$.


title:
Abelian Z-theory: NLSM amplitudes and alpha'-corrections from the open
  string

abstract:
  In this paper we derive the tree-level S-matrix of the effective theory of
Goldstone bosons known as the non-linear sigma model (NLSM) from string theory.
This novel connection relies on a recent realization of tree-level
open-superstring S-matrix predictions as a double copy of super-Yang-Mills
theory with Z-theory --- the collection of putative scalar effective field
theories encoding all the alpha'-dependence of the open superstring. Here we
identify the color-ordered amplitudes of the NLSM as the low-energy limit of
abelian Z-theory. This realization also provides natural higher-derivative
corrections to the NLSM amplitudes arising from higher powers of alpha' in the
abelian Z-theory amplitudes, and through double copy also to Born-Infeld and
Volkov-Akulov theories. The Kleiss-Kuijf and Bern-Carrasco-Johansson relations
obeyed by Z-theory amplitudes thereby apply to all alpha'-corrections of the
NLSM. As such we naturally obtain a cubic-graph parameterization for the
abelian Z-theory predictions whose kinematic numerators obey the duality
between color and kinematics to all orders in alpha'.


title:
Resonantly enhanced second-harmonic generation using III-V semiconductor
  all-dielectric metasurfaces

abstract:
  Nonlinear optical phenomena in nanostructured materials have been challenging
our perceptions of nonlinear optical processes that have been explored since
the invention of lasers. For example, the ability to control optical field
confinement, enhancement, and scattering almost independently, allows nonlinear
frequency conversion efficiencies to be enhanced by many orders of magnitude
compared to bulk materials. Also, the subwavelength length scale renders phase
matching issues irrelevant. Compared with plasmonic nanostructures, dielectric
resonator metamaterials show great promise for enhanced nonlinear optical
processes due to their larger mode volumes. Here, we present, for the first
time, resonantly enhanced second-harmonic generation (SHG) using Gallium
Arsenide (GaAs) based dielectric metasurfaces. Using arrays of cylindrical
resonators we observe SHG enhancement factors as large as 104 relative to
unpatterned GaAs. At the magnetic dipole resonance we measure an absolute
nonlinear conversion efficiency of ~2X10^(-5) with ~3.4 GW/cm2 pump intensity.
The polarization properties of the SHG reveal that both bulk and surface
nonlinearities play important roles in the observed nonlinear process.


title:
Active Brownian motion of emulsion droplets: Coarsening dynamics at the
  interface and rotational diffusion

abstract:
  A micron-sized droplet of bromine water immersed in a surfactant-laden oil
phase can swim (S. Thutupalli, R. Seemann, S. Herminghaus, New J. Phys. 13
073021 (2011)). The bromine reacts with the surfactant at the droplet interface
and generates a surfactant mixture. It can spontaneously phase-separate due to
solutocapillary Marangoni flow, which propels the droplet. We model the system
by a diffusion-advection-reaction equation for the mixture order parameter at
the interface including thermal noise and couple it to fluid flow. Going beyond
previous work, we illustrate the coarsening dynamics of the surfactant mixture
towards phase separation in the axisymmetric swimming state. Coarsening
proceeds in two steps: an initially slow growth of domain size followed by a
nearly ballistic regime. On larger time scales thermal fluctuations in the
local surfactant composition initiates random changes in the swimming direction
and the droplet performs a persistent random walk, as observed in experiments.
Numerical solutions show that the rotational correlation time scales with the
square of the inverse noise strength. We confirm this scaling by a perturbation
theory for the fluctuations in the mixture order parameter and thereby identify
the active emulsion droplet as an active Brownian particle.


title: The generation problem in Thompson group $F$

abstract:
  We show that the generation problem in Thompson group $F$ is decidable, i.e.,
there is an algorithm which decides if a finite set of elements of $F$
generates the whole $F$. The algorithm makes use of the Stallings $2$-core of
subgroups of $F$, which can be defined in an analogue way to the Stallings core
of subgroups of a finitely generated free group. Further study of the Stallings
$2$-core of subgroups of $F$ provides a solution to another algorithmic problem
in $F$. Namely, given a finitely generated subgroup $H$ of $F$, it is decidable
if $H$ acts transitively on the set of finite dyadic fractions $\mathcal D$.
Other applications of the study include the construction of new maximal
subgroups of $F$ of infinite index, among which, a maximal subgroup of infinite
index which acts transitively on the set $\mathcal D$ and the construction of
an elementary amenable subgroup of $F$ which is maximal in a normal subgroup of
$F$.


title: Current status of MSSM Higgs sector with LHC 13 TeV data

abstract:
  ATLAS and CMS collaborations have reported the results on the Higgs search
analyzing $\sim 36$ fb$^{-1}$ data from Run-II of LHC at 13 TeV. In this work,
we study the Higgs sector of the phenomenological Minimal Supersymmetric
Standard Model, in light of the recent Higgs data, by studying separately the
impact of Run-I and Run-II data. One of the major impacts of the new data on
the parameter space comes from the direct searches of neutral CP-even and
CP-odd heavy Higgses ($H$ and $A$, respectively) in the $H/A \to \tau^{+}
\tau^{-}$ channel which disfavours high $\tan\beta$ regions more efficiently
than Run-I data. Secondly, we show that the latest result of the rare radiative
decay of $B$ meson imposes a slightly stronger constraint on low $\tan \beta$
and low $M_A$ region of the parameter space, as compared to its previous
measurement. Further, we find that in a global fit Run-II light Higgs signal
strength data is almost comparable in strength with the corresponding Run-I
data. Finally, we discuss scenarios with the Heavy Higgs boson decaying into
electroweakinos and third generation squarks and sleptons.


title: Critical Telomerase Activity for Uncontrolled Cell Growth

abstract:
  The lengths of the telomere regions of chromosomes in a population of cells
are modelled using a chemical master equation formalism, from which the
evolution of the average number of cells of each telomere length is extracted.
In particular, the role of the telomere-elongating enzyme telomerase on these
dynamics is investigated. We show that for biologically relevant rates of cell
birth and death, one finds a critical rate, R_crit, of telomerase activity such
that the total number of cells diverges. Further, R_crit is similar in
magnitude to the rates of mitosis and cell death. The possible relationship of
this result to replicative immortality and its associated hallmark of cancer is
discussed.


title: Substructure of fuzzy dark matter haloes

abstract:
  We derive the halo mass function (HMF) for fuzzy dark matter (FDM) by solving
the excursion set problem explicitly with a mass-dependent barrier function,
which has not been done before. We find that compared to the naive approach of
the Sheth--Tormen HMF for FDM, our approach has a higher cut off mass and the
cut off mass changes less strongly with redshifts. Using merger trees
constructed with a modified version of the Lacey & Cole formalism that accounts
for suppressed small scale power and the scale-dependent growth of FDM haloes
and the semi-analytic GALACTICUS code, we study the statistics of halo
substructure including the effects from dynamical friction and tidal stripping.
We find that if the dark matter is a mixture of cold dark matter (CDM) and FDM,
there will be a suppression on the halo substructure on small scales which may
be able to solve the Missing Satellites Problem faced by the pure CDM model.
The suppression becomes stronger with increasing FDM fraction or decreasing FDM
mass. Thus, it may be used to constrain the FDM model.


title: Ferromagnetism and glassiness on the surface of topological insulators

abstract:
  We investigate the nature of the ordering among magnetic adatoms, randomly
deposited on the surface of topological insulators. Restricting ourselves to
dilute impurity and weak coupling (between itinerant fermion and magnetic
impurities) limit, we show that for arbitrary amount of chemical doping away
from the apex of the surface Dirac cone the magnetic impurities tend to arrange
themselves in a spin-density-wave pattern, with the periodicity approximately
$\pi/k_F$, where $k_F$ is the Fermi wave vector, when magnetic moment for
impurity adatoms is isotropic. However, when magnetic moment possesses strong
Ising or easy-axis anisotropy, pursuing both analytical and numerical
approaches we show that the ground state is ferromagnetic for low to moderate
chemical doping, despite the fragmentation of the system into multiple
ferromagnetic islands. For high doping away from the Dirac point as well, the
system appears to fragment into many ferromagnetic islands, but the
magnetization in these islands is randomly distributed. Such magnetic ordering
with net zero magnetization, is referred here as ferromagnetic spin glass,
which is separated from the pure ferromagnet state by a first order phase
transition. We generalize our analysis for cubic topological insulators
(supporting three Dirac cones on a surface) and demonstrate that the nature of
magnetic orderings and the transition between them remains qualitatively the
same. We also discuss the possible relevance of our analysis to recent
experiments.


title: Transverse-momentum-dependent gluon distributions from JIMWLK evolution

abstract:
  Transverse-momentum-dependent (TMD) gluon distributions have different
operator definitions, depending on the process under consideration. We study
that aspect of TMD factorization in the small-x limit, for the various
unpolarized TMD gluon distributions encountered in the literature. To do this,
we consider di-jet production in hadronic collisions, since this process allows
to be exhaustive with respect to the possible operator definitions, and is
suitable to be investigated at small x. Indeed, for forward and nearly
back-to-back jets, one can apply both the TMD factorization and Color Glass
Condensate (CGC) approaches to compute the di-jet cross-section, and compare
the results. Doing so, we show that both descriptions coincide, and we show how
to express the various TMD gluon distributions in terms of CGC correlators of
Wilson lines, while keeping Nc finite. We then proceed to evaluate them by
solving the JIMWLK equation numerically. We obtain that at large transverse
momentum, the process dependence essentially disappears, while at small
transverse momentum, non-linear saturation effects impact the various TMD gluon
distributions in very different ways. We notice the presence of a geometric
scaling regime for all the TMD gluon distributions studied: the "dipole" one,
the Weizs\"acker-Williams one, and the six others involved in forward di-jet
production.


title: Constrained Reconstruction in MUSCL-type Finite Volume Schemes

abstract:
  In this paper we are concerned with the stabilization of MUSCL-type finite
volume schemes in arbitrary space dimensions. We consider a number of limited
reconstruction techniques which are defined in terms inequality-constrained
linear or quadratic programming problems on individual grid elements. No
restrictions to the conformity of the grid or the shape of its elements are
made. In the special case of Cartesian meshes a novel QP reconstruction is
shown to coincide with the widely used Minmod reconstruction. The accuracy and
overall efficiency of the stabilized second-order finite volume schemes is
supported by numerical experiments.


title:
On generalized Vietoris' number sequences - origins, properties and
  applications

abstract:
  Ruscheweyh and Salinas showed in 2004 the relationship of a celebrated
theorem of Vietoris (1958) about the positivity of certain sine and cosine sums
with the function theoretic concept of stable holomorphic functions in the unit
disc. The present paper shows that the coefficient sequence in Vietoris'
theorem is identical with the number sequence that characterizes generalized
Appell sequences of homogeneous Clifford holomorphic polynomials in
$\mathbb{R}^3.$ The paper studies one-parameter generalizations of Vietoris'
number sequence, their properties as well as their role in the framework of
Hypercomplex Function Theory.


title:
The F-GAMMA program: Multi-frequency study of Active Galactic Nuclei in
  the Fermi era. Program description and the first 2.5 years of monitoring

abstract:
  To fully exploit the scientific potential of the Fermi mission, we initiated
the F-GAMMA program. Between 2007 and 2015 it was the prime provider of
complementary multi-frequency monitoring in the radio regime. We quantify the
radio variability of gamma-ray blazars. We investigate its dependence on source
class and examine whether the radio variability is related to the gamma-ray
loudness. Finally, we assess the validity of a putative correlation between the
two bands. The F-GAMMA monitored monthly a sample of about 60 sources at up to
twelve radio frequencies between 2.64 and 228.39 GHz. We perform a time series
analysis on the first 2.5-year dataset to obtain variability parameters. A
maximum likelihood analysis is used to assess the significance of a correlation
between radio and gamma-ray fluxes. We present light curves and spectra
(coherent within ten days) obtained with the Effelsberg 100-m and IRAM 30-m
telescopes. All sources are variable across all frequency bands with amplitudes
increasing with frequency up to rest frame frequencies of around 60 - 80 GHz as
expected by shock-in-jet models. Compared to FSRQs, BL Lacs show systematically
lower variability amplitudes, brightness temperatures and Doppler factors at
lower frequencies, while the difference vanishes towards higher ones. The time
scales appear similar for the two classes. The distribution of spectral indices
appears flatter or more inverted at higher frequencies for BL Lacs. Evolving
synchrotron self-absorbed components can naturally account for the observed
spectral variability. We find that the Fermi-detected sources show larger
variability amplitudes as well as brightness temperatures and Doppler factors,
than non-detected ones. Flux densities at 86.2 and 142.3 GHz correlate with 1
GeV fluxes at a significance level better than 3sigma, implying that gamma rays
are produced very close to the mm-band emission region.


title: A New Algorithm for Approximating the Least Concave Majorant

abstract:
  The least concave majorant, $\hat F$, of a continuous function $F$ on a
closed interval, $I$, is defined by \[ \hat F (x) = \inf \left\{ G(x): G \geq
F, G \mbox{ concave}\right\},\; x \in I. \] We present here an algorithm, in
the spirit of the Jarvis March, to approximate the least concave majorant of a
differentiable piecewise polynomial function of degree at most three on $I$.
Given any function $F \in \mathcal{C}^4(I)$, it can be well-approximated on $I$
by a clamped cubic spline $S$. We show that $\hat S$ is then a good
approximation to $\hat F$.
  We give two examples, one to illustrate, the other to apply our algorithm.


title: Approximate Universal Relations for Neutron Stars and Quark Stars

abstract:
  Neutron stars and quark stars are ideal laboratories to study fundamental
physics at supra nuclear densities and strong gravitational fields.
Astrophysical observables, however, depend strongly on the star's internal
structure, which is currently unknown due to uncertainties in the equation of
state. Universal relations, however, exist among certain stellar observables
that do not depend sensitively on the star's internal structure. One such set
of relations is between the star's moment of inertia ($I$), its tidal Love
number (Love) and its quadrupole moment ($Q$), the so-called I-Love-Q
relations. Similar relations hold among the star's multipole moments, which
resemble the well-known black hole no-hair theorems. Universal relations break
degeneracies among astrophysical observables, leading to a variety of
applications: (i) X-ray measurements of the nuclear matter equation of state,
(ii) gravitational wave measurements of the intrinsic spin of inspiraling
compact objects, and (iii) gravitational and astrophysical tests of General
Relativity that are independent of the equation of state. We here review how
the universal relations come about and all the applications that have been
devised to date.


title: A new gamma-ray loud, eclipsing low-mass X-ray binary

abstract:
  We report the discovery of an eclipsing low-mass X-ray binary at the center
of the 3FGL error ellipse of the unassociated Fermi/Large Area Telescope
gamma-ray source 3FGL J0427.9-6704. Photometry from OGLE and the SMARTS 1.3-m
telescope and spectroscopy from the SOAR telescope have allowed us to classify
the system as an eclipsing low-mass X-ray binary (P = 8.8 hr) with a main
sequence donor and a neutron star accretor. Broad double-peaked H and He
emission lines suggest the ongoing presence of an accretion disk. Remarkably,
the system shows shows separate sets of absorption lines associated with the
accretion disk and the secondary, and we use their radial velocities to find
evidence for a massive (~ 1.8-1.9 M_sun) neutron star primary. In addition to a
total X-ray eclipse of duration ~ 2200 s observed with NuSTAR, the X-ray light
curve also shows properties similar to those observed among known transitional
millisecond pulsars: short-term variability, a hard power-law spectrum (photon
index ~ 1.7), and a comparable 0.5-10 keV luminosity (~ 2.4 x 10^33 erg/s). We
find tentative evidence for a partial (~ 60%) gamma-ray eclipse at the same
phase as the X-ray eclipse, suggesting the gamma-ray emission may not be
confined to the immediate region of the compact object. The favorable
inclination of this binary is promising for future efforts to determine the
origin of gamma-rays among accreting neutron stars.


title:
Low-metallicity Absorbers Account for Half of the Dense Circumgalactic
  Gas at z < 1

abstract:
  We present an analysis of the metallicity distribution of the dense
circumgalactic medium (CGM) of galaxies at 0.1 < z < 1.1 as probed by partial
Lyman limit systems (pLLSs, 16.1 < log N(H I) < 17.2) and LLSs (17.2 < log N(H
I) < 17.7 in our sample). The new H I-selected sample, drawn from our HST COS
G140L snapshot survey of 61 QSOs, has 20 pLLSs and 10 LLSs. Combined with our
previous survey, we have a total of 44 pLLSs and 11 LLSs. We find that the
metallicity distribution of the pLLSs is bimodal at z < 1, with a minimum at
[X/H] = -1. The low-metallicity peak comprises (57 +/- 8)% of the pLLSs and is
centered at [X/H] ~ -1.87 (1.3% solar metallicity), while the high-metallicity
peak is centered at [X/H] ~ -0.32 (48% solar metallicity). Although the sample
of LLSs is still small, there is some evidence that the metallicity
distributions of the LLSs and pLLSs are different, with a far lower fraction of
very metal-poor ([X/H] < -1.4) LLSs than pLLSs. The fraction of LLSs with [X/H]
< -1 is similar to that found in pLLSs (~56%). However, higher H I column
density absorbers (log N(H I) > 19.0) show a much lower fraction of metal-poor
gas; therefore, the metallicity distribution of gas in and around galaxies
depends sensitively on N(H I) at z < 1. We interpret the high-metallicity
([X/H] > -1) pLLSs and LLSs as arising in outflows, recycling winds, and
tidally-stripped gas around galaxies. The low-metallicity pLLSs and LLSs imply
that the CGM of z < 1 galaxies is also host to a substantial mass of cool,
dense, low-metallicity gas that may ultimately accrete onto the galaxies.


title: Cosmic ray-driven galactic winds: streaming or diffusion?

abstract:
  Cosmic rays (CRs) have recently re-emerged as attractive candidates for
mediating feedback in galaxies because of their long cooling timescales. They
can have energy densities comparable to the thermal gas, but do not suffer
catastrophic cooling losses. Recent simulations have shown that the momentum
and energy deposited by CRs moving with respect to the ambient medium can drive
galactic winds. However, simulations are hampered by our ignorance of the
details of CR transport. Two key limits previously considered model CR
transport as a purely diffusive process (with a constant diffusion coefficient)
and as an advective streaming process. With a series of GADGET simulations, we
compare and contrast the results of these different assumptions. In idealised
three-dimensional galaxy formation models, we show that these two cases result
in significant differences for the galactic wind mass loss rates and star
formation suppression in dwarf galaxies with halo masses
$M\approx10^{10}\,\textrm{M}_\odot$: diffusive CR transport results in more
than ten times larger mass loss rates compared to CR streaming models. We
demonstrate that this is largely due to the excitation of Alfv\'en waves during
the CR streaming process that drains energy from the CR population to the
thermal gas, which is subsequently radiated away. By contrast, CR diffusion
conserves the CR energy in the absence of adiabatic changes and if CRs are
efficiently scattered by Alfv\'en waves that are propagating up the CR
gradient. Moreover, because pressure gradients are preserved by CR streaming,
but not diffusion, the two can have a significantly different dynamical
evolution regardless of this energy exchange. In particular, the constant
diffusion coefficients usually assumed can lead to unphysically high CR fluxes.


title: Dynamical response near quantum critical points

abstract:
  We study high frequency response functions, notably the optical conductivity,
in the vicinity of quantum critical points (QCPs) by allowing for both detuning
from the critical coupling and finite temperature. We consider general
dimensions and dynamical exponents. This leads to a unified understanding of
sum rules. In systems with emergent Lorentz invariance, powerful methods from
conformal field theory allow us to fix the high frequency response in terms of
universal coefficients. We test our predictions analytically in the large-N
O(N) model and using the gauge-gravity duality, and numerically via Quantum
Monte Carlo simulations on a lattice model hosting the interacting
superfluid-insulator QCP. In superfluid phases, interacting Goldstone bosons
qualitatively change the high frequency optical conductivity, and the
corresponding sum rule.

categories: cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech hep-th


title:
Nebular Emission Line Ratios in z~2-3 Star-Forming Galaxies with
  KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and
  Nitrogen-to-Oxygen Ratio

abstract:
  We present a detailed study of the rest-optical (3600-7000 Angstrom) nebular
spectra of ~380 star-forming galaxies at z~2-3 obtained with Keck/MOSFIRE as
part of the Keck Baryonic Structure Survey (KBSS). The KBSS-MOSFIRE sample is
representative of star-forming galaxies at these redshifts, with stellar masses
M*=10^9-10^11.5 M_sun and star formation rates SFR=3-1000 M_sun/yr. We focus on
robust measurements of many strong diagnostic emission lines for individual
galaxies: [O II]3727,3729, [Ne III]3869, H-beta, [O III]4960,5008, [N
II]6549,6585, H-alpha, and [S II]6718,6732. Comparisons with observations of
typical local galaxies from the Sloan Digital Sky Survey (SDSS) and between
subsamples of KBSS-MOSFIRE show that high-redshift galaxies exhibit a number of
significant differences in addition to the well-known offset in log([O
III]/H-beta) and log([N II]/H-alpha). We argue that the primary difference
between H II regions in z~2.3 galaxies and those at z~0 is an enhancement in
the degree of nebular excitation, as measured by [O III]/H-beta and R23=log[([O
III]+[O II])/H-beta]. At the same time, KBSS-MOSFIRE galaxies are ~10 times
more massive than z~0 galaxies with similar ionizing spectra and have higher
N/O (likely accompanied by higher O/H) at fixed excitation. These results
indicate the presence of harder ionizing radiation fields at fixed N/O and O/H
relative to typical z~0 galaxies, consistent with Fe-poor stellar population
models that include massive binaries, and highlight a population of massive,
high-specific star formation rate galaxies at high-redshift with systematically
different star formation histories than galaxies of similar stellar mass today.


title:
The Cosmic Evolution of the Metallicity Distribution of Ionized Gas
  Traced by Lyman Limit Systems

abstract:
  We present the first results from our KODIAQ Z survey aimed to determine the
metallicity distribution and physical properties of the z>2 partial and full
Lyman limit systems (pLLSs and LLSs; 16.2<log N(HI)<19), which are probed of
the interface regions between the intergalactic medium (IGM) and galaxies. We
study 31 HI-selected pLLSs and LLSs at 2.3<z<3.3 observed with Keck/HIRES in
absorption against background QSOs. We compare the column densities of
metal-ions to HI and use photoionization models to assess the metallicity. The
metallicity distribution of the pLLSs/LLSs at 2.3<z<3.3 is consistent with a
unimodal distribution peaking at [X/H]=-2. The metallicity distribution of
these absorbers therefore evolves markedly with z since at z<1 it is bimodal
with peaks at [X/H]=-1.8 and -0.3. There is a substantial fraction (25-41%) of
pLLSs/LLSs with metallicities well below those of damped Lya absorbers (DLAs)
at any studied z from z<1 to z~2-4, implying reservoirs of metal-poor cool,
dense gas in the IGM/galaxy interface at all z. However, the gas probed by
pLLSs and LLSs is rarely pristine, with a fraction 3-18% for pLLSs/LLSs with
[X/H]<-3. We find C/alpha enhancement in several pLLSs and LLSs in the
metallicity range -2<[X/H]<-0.5, where C/alpha is 2-5 times larger than
observed in Galactic metal-poor stars or high redshift DLAs at similar
metallicities. This is likely caused by preferential ejection of carbon from
metal-poor galaxies into their surroundings.


title: Discrete time crystals: rigidity, criticality, and realizations

abstract:
  Despite being forbidden in equilibrium, spontaneous breaking of time
translation symmetry can occur in periodically driven, Floquet systems with
discrete time-translation symmetry. The period of the resulting discrete time
crystal is quantized to an integer multiple of the drive period, arising from a
combination of collective synchronization and many body localization. Here, we
consider a simple model for a one dimensional discrete time crystal which
explicitly reveals the rigidity of the emergent oscillations as the drive is
varied. We numerically map out its phase diagram and compute the properties of
the dynamical phase transition where the time crystal melts into a trivial
Floquet insulator. Moreover, we demonstrate that the model can be realized with
current experimental technologies and propose a blueprint based upon a one
dimensional chain of trapped ions. Using experimental parameters (featuring
long-range interactions), we identify the phase boundaries of the
ion-time-crystal and propose a measurable signature of the symmetry breaking
phase transition.

categories: cond-mat.dis-nn cond-mat.quant-gas cond-mat.stat-mech cond-mat.str-el quant-ph


title:
Resolving Close Encounters: Stability in the HD 5319 and HD 7924
  Planetary Systems

abstract:
  Radial velocity searches for exoplanets have detected many multi-planet
systems around nearby bright stars. An advantage of this technique is that it
generally samples the orbit outside of inferior/superior conjunction,
potentially allowing the Keplerian elements of eccentricity and argument of
periastron to be well characterized. The orbital architectures for some of
these systems show signs of close planetary encounters that may render the
systems unstable as described. We provide an in-depth analysis of two such
systems: HD 5319 and HD 7924, for which the scenario of coplanar orbits results
in rapid destabilization of the systems. The poorly constrained periastron
arguments of the outer planets in these systems further emphasizes the need for
detailed investigations. An exhaustive scan of parameters space via dynamical
simulations reveals specific mutual inclinations between the two outer planets
in each system that allow for stable configurations over long timescales. We
compare these configurations with those presented by mean-motion resonance as
possible stability sources. Finally, we discuss the relevance to interpretation
of multi-planet Keplerian orbits and suggest additional observations that will
help to resolve the system stabilities.


title:
First results from the MADCASH Survey: A Faint Dwarf Galaxy Companion to
  the Low Mass Spiral Galaxy NGC 2403 at 3.2 Mpc

abstract:
  We report the discovery of the faintest known dwarf galaxy satellite of an
LMC stellar-mass host beyond the Local Group, based on deep imaging with
Subaru/Hyper Suprime-Cam. MADCASH J074238+652501-dw lies $\sim$35 kpc in
projection from NGC 2403, a dwarf spiral galaxy at $D$$\approx$3.2 Mpc. This
new dwarf has $M_{g} = -7.4\pm0.4$ and a half-light radius of $168\pm70$ pc, at
the calculated distance of $3.39\pm0.41$ Mpc. The color-magnitude diagram
reveals no evidence of young stellar populations, suggesting that MADCASH
J074238+652501-dw is an old, metal-poor dwarf similar to low luminosity dwarfs
in the Local Group. The lack of either detected HI gas ($M_{\rm HI}/L_{V} <
0.69 M_\odot/L_\odot$, based on Green Bank Telescope observations) or $GALEX$
NUV/FUV flux enhancement is consistent with a lack of young stars. This is the
first result from the MADCASH (Magellanic Analog Dwarf Companions And Stellar
Halos) survey, which is conducting a census of the stellar substructure and
faint satellites in the halos of Local Volume LMC analogs via resolved stellar
populations. Models predict a total of $\sim$4-10 satellites at least as
massive as MADCASH J074238+652501-dw around a host with the mass of NGC 2403,
with 2-3 within our field of view, slightly more than the one such satellite
observed in our footprint.


title:
Searching for photon-sector Lorentz violation using gravitational-wave
  detectors

abstract:
  We study the prospects for using interferometers in gravitational-wave
detectors as tools to search for photon-sector violations of Lorentz symmetry.
Existing interferometers are shown to be exquisitely sensitive to tiny changes
in the effective refractive index of light occurring at frequencies around and
below the microhertz range, including at the harmonics of the frequencies of
the Earth's sidereal rotation and annual revolution relevant for tests of
Lorentz symmetry. We use preliminary data obtained by the Laser Interferometer
Gravitational-Wave Observatory (LIGO) in 2006-2007 to place constraints on
coefficients for Lorentz violation in the photon sector exceeding current
limits by about four orders of magnitude.


title: Tailored jump operators for purely dissipative quantum magnetism

abstract:
  I propose an archtitecture for the realization of dissipative quantum
many-body spin models. The dissipative processes are mediated by interactions
with auxiliary particles and lead to a widely tunable class of correlated
quantum jump operators. These findings enable the investigation of purely
dissipative spin models, where coherent dynamics is entirely absent. I provide
a detailed review of a recently introduced variational method to analyze such
dissipative quantum many-body systems, and I discuss a specific example in
terms of a purely dissipative Heisenberg model, for which I find an additional
disordered phase that is not present in the corresponding ground state phase
diagram.


title: On domains of noncommutative rational functions

abstract:
  In this paper the stable extended domain of a noncommutative rational
function is introduced and it is shown that it can be completely described by a
monic linear pencil from the minimal realization of the function. This result
amends the singularities theorem of Kalyuzhnyi-Verbovetskyi and Vinnikov.
Furthermore, for noncommutative rational functions which are regular at a
scalar point it is proved that their domains and stable extended domains
coincide.


title: Multipartite Entanglement in Stabilizer Tensor Networks

abstract:
  Despite the fundamental importance of quantum entanglement in many-body
systems, our understanding is mostly limited to bipartite situations. Indeed,
even defining appropriate notions of multipartite entanglement is a significant
challenge for general quantum systems. In this work, we initiate the study of
multipartite entanglement in a rich, yet tractable class of quantum states
called stabilizer tensor networks. We demonstrate that, for generic stabilizer
tensor networks, the geometry of the tensor network informs the multipartite
entanglement structure of the state. In particular, we show that the average
number of Greenberger-Horne-Zeilinger (GHZ) triples that can be extracted from
a stabilizer tensor network is small, implying that tripartite entanglement is
scarce. This, in turn, restricts the higher-partite entanglement structure of
the states. Recent research in quantum gravity found that stabilizer tensor
networks reproduce important structural features of the AdS/CFT correspondence,
including the Ryu-Takayanagi formula for the entanglement entropy and certain
quantum error correction properties. Our results imply a new operational
interpretation of the monogamy of the Ryu-Takayanagi mutual information and an
entropic diagnostic for higher-partite entanglement. Our technical
contributions include a spin model for evaluating the average GHZ content of
stabilizer tensor networks, as well as a novel formula for the third moment of
random stabilizer states, which we expect to find further applications in
quantum information.


title: Super-quantum curves from super-eigenvalue models

abstract:
  In modern mathematical and theoretical physics various generalizations, in
particular supersymmetric or quantum, of Riemann surfaces and complex algebraic
curves play a prominent role. We show that such supersymmetric and quantum
generalizations can be combined together, and construct supersymmetric quantum
curves, or super-quantum curves for short. Our analysis is conducted in the
formalism of super-eigenvalue models: we introduce $\beta$-deformed version of
those models, and derive differential equations for associated
$\alpha/\beta$-deformed super-matrix integrals. We show that for a given model
there exists an infinite number of such differential equations, which we
identify as super-quantum curves, and which are in one-to-one correspondence
with, and have the structure of, super-Virasoro singular vectors. We discuss
potential applications of super-quantum curves and prospects of other
generalizations.


title:
L-band Spectroscopy with Magellan-AO/Clio2: First Results on Young
  Low-Mass Companions

abstract:
  L-band spectroscopy is a powerful probe of cool low-gravity atmospheres: The
P, Q, and R branch fundamental transitions of methane near 3.3 $\mu$m provide a
sensitive probe of carbon chemistry; cloud thickness modifies the spectral
slope across the band; and H$_{3}^{+}$ opacity can be used to detect aurorae.
Many directly imaged gas-giant companions to nearby young stars exhibit L-band
fluxes distinct from the field population of brown dwarfs at the same effective
temperature. Here we describe commissioning the L-band spectroscopic mode of
Clio2, the 1-5 $\mu$m instrument behind the Magellan adaptive-optics system. We
use this system to measure L-band spectra of directly imaged companions. Our
spectra are generally consistent with the parameters derived from previous
near-infrared spectra for these late M to early L type objects. Therefore,
deviations from the field sequence are constrained to occur below 1500 K. This
range includes the L-T transition for field objects and suggests that observed
discrepancies are due to differences in cloud structure and CO/CH$_{4}$
chemistry.


title: Quantum Criticality and DBI Magneto-resistance

abstract:
  We use the DBI action from string theory and holography to study the
magneto-resistance at quantum criticality with hyperscaling violation. We find
and analyze a rich class of scaling behaviors for the magneto-resistance. A
special case describes the scaling results found in pnictides by Hayers et al.
in~\cite{analytis}.


title: Interpreting Flux from Broadband Photometry

abstract:
  We discuss the transformation of observed photometry into flux for the
creation of spectral energy distributions and the computation of bolometric
luminosities. We do this in the context of supernova studies, particularly as
observed with the Swift spacecraft, but the concepts and techniques should be
applicable to many other types of sources and wavelength regimes. Traditional
methods of converting observed magnitudes to flux densities are not very
accurate when applied to UV photometry. Common methods for extinction and the
integration of pseudo-bolometric fluxes can also lead to inaccurate results.
The sources of inaccuracy, though, also apply to other wavelengths. Because of
the complicated nature of translating broad-band photometry into monochromatic
flux densities, comparison between observed photometry and a spectroscopic
model is best done by comparing in the natural units of the observations. We
recommend that integrated flux measurements be made using a spectrum or
spectral energy distribution which is consistent with the multi-band photometry
rather than converting individual photometric measurements to flux densities,
linearly interpolating between the points, and integrating. We also highlight
some specific areas where the UV flux can be mischaracterized.