title:
An Empirical Comparison of Formalisms for Modelling and Analysis of
  Dynamic Reconfiguration of Dependable Systems

abstract:
  This paper uses a case study to evaluate empirically three formalisms of
different kinds for their suitability for the modelling and analysis of dynamic
reconfiguration of dependable systems. The requirements on an ideal formalism
for dynamic software reconfiguration are defined. The reconfiguration of an
office workflow for order processing is described, and the requirements on the
reconfiguration of the workflow are defined. The workflow is modelled using the
Vienna Development Method ($\mathrm{VDM}$), conditional partial order graphs
($\mathrm{CPOGs}$), and the basic Calculus of Communicating Systems for dynamic
process reconfiguration (basic $\mathrm{CCS^{dp}}$), and verification of the
reconfiguration requirements is attempted using the models. The formalisms are
evaluated according to their ability to model the reconfiguration of the
workflow, to verify the requirements on the workflow's reconfiguration, and to
meet the requirements on an ideal formalism.


title:
Characterizing Elastic Turbulence in Channel Flows at Low Reynolds
  number

abstract:
  We experimentally investigate the flow of a viscoelastic fluid in a parallel
shear geometry at low Reynolds number. As the flow becomes unstable via a
nonlinear subcritical instability, velocimetry measurements show non-periodic
fluctuations over a broad range of frequencies and wavelengths, consistent with
the main features of elastic turbulence. Using the same experimental setup, we
compare these features to those in the flow around cylinders, which is upstream
to the parallel shear region; we find significant differences in power spectra
scaling, intermittency statistics, and flow structures. We propose a simple
mechanism to explain the growth of velocity fluctuations in parallel shear
flows based on polymer stretching due to fluctuations in streamwise velocity
gradients.


title:
Multi-component vapor-liquid equilibrium model for LES and application
  to ECN Spray A

abstract:
  We present and evaluate a detailed multi-species two-phase thermodynamic
equilibrium model for large-eddy simulations (LES) of liquid-fuel injection and
mixing at high pressure. The model can represent the coexistence of
supercritical states and multi-component subcritical two-phase states. LES
results for the transcritical Spray A of the Engine Combustion Network (ECN)
are found to agree very well to available experimental data. We also address
well-known numerical challenges of trans- and supercritical fluid mixing and
compare a fully conservative formulation to a quasi conservative formulation of
the governing equations. Our results prove physical and numerical consistency
of both methods on fine grids and demonstrate the effects of energy
conservation errors associated with the quasi conservative formulation on
typical LES grids.


title:
Variation Of The Tully-Fisher Relation As A Function Of The Magnitude
  Interval Of A Sample Of Galaxies

abstract:
  In this paper we carry out a preliminary study of the dependence of the
Tully-Fisher Relation (TFR) with the width and intensity level of the absolute
magnitude interval of a limited sample of 2411 galaxies taken from Mathewson \&
Ford (1996). The galaxies in this sample do not differ significantly in
morphological type, and are distributed over an $\sim11$-magnitude interval
($-24.4 < I < -13.0$). We take as directives the papers by Nigoche-Netro et al.
(2008, 2009, 2010) in which they study the dependence of the Kormendy (KR), the
Fundamental Plane (FPR) and the Faber-Jackson Relations (FJR) with the
magnitude interval within which the observed galaxies used to derive these
relations are contained. We were able to characterise the behaviour of the TFR
coefficients $(\alpha, \beta)$ with respect to the width of the magnitude
interval as well as with the brightness of the galaxies within this magnitude
interval. We concluded that the TFR for this specific sample of galaxies
depends on observational biases caused by arbitrary magnitude cuts, which in
turn depend on the width and intensity of the chosen brightness levels.


title: Chronodes: Interactive Multi-focus Exploration of Event Sequences

abstract:
  The advent of mobile health technologies presents new challenges that
existing visualizations, interactive tools, and algorithms are not yet designed
to support. In dealing with uncertainty in sensor data and high-dimensional
physiological records, we must seek to improve current tools that make sense of
health data from traditional perspectives in event-based trend discovery. With
Chronodes, a system developed to help researchers collect, interpret, and model
mobile health (mHealth) data, we posit a series of interaction techniques that
enable new approaches to understanding and exploring event-based data. From
numerous and discontinuous mobile health data streams, Chronodes finds and
visualizes frequent event sequences that reveal common chronological patterns
across participants and days. By then promoting the sequences as interactive
elements, Chronodes presents opportunities for finding, defining, and comparing
cohorts of participants that exhibit particular behaviors. We applied Chronodes
to a real 40GB mHealth dataset capturing about 400 hours of data. Through our
pilot study with 20 behavioral and biomedical health experts, we gained
insights into Chronodes' efficacy, limitations, and potential applicability to
a wide range of healthcare scenarios.


title: Scheduling Nonlinear Sensors for Stochastic Process Estimation

abstract:
  In this paper, we focus on activating only a few sensors, among many
available, to estimate the state of a stochastic process of interest. This
problem is important in applications such as target tracking and simultaneous
localization and mapping (SLAM). It is challenging since it involves stochastic
systems whose evolution is largely unknown, sensors with nonlinear
measurements, and limited operational resources that constrain the number of
active sensors at each measurement step. We provide an algorithm applicable to
general stochastic processes and nonlinear measurements whose time complexity
is linear in the planning horizon and whose performance is a multiplicative
factor 1/2 away from the optimal performance. This is notable because the
algorithm offers a significant computational advantage over the polynomial-time
algorithm that achieves the best approximation factor 1/e. In addition, for
important classes of Gaussian processes and nonlinear measurements corrupted
with Gaussian noise, our algorithm enjoys the same time complexity as even the
state-of-the-art algorithms for linear systems and measurements. We achieve our
results by proving two properties for the entropy of the batch state vector
conditioned on the measurements: a) it is supermodular in the choice of the
sensors; b) it has a sparsity pattern (involves block tri-diagonal matrices)
that facilitates its evaluation at each sensor set.


title:
Exact zeros of entanglement for arbitrary rank-two mixtures: how a
  geometric view of the zero-polytope makes life more easy

abstract:
  Here I present a method how intersections of a certain density matrix of rank
two with the zero-polytope can be calculated exactly. This is a purely
geometrical procedure which thereby is applicable to obtaining the zeros of SL-
and SU-invariant entanglement measures of arbitrary polynomial degree. I
explain this method in detail for a recently unsolved problem. In particular, I
show how a three-dimensional view, namely in terms of the Boch-sphere analogy,
solves this problem immediately. To this end, I determine the zero-polytope of
the three-tangle, which is an exact result up to computer accuracy, and
calculate upper bounds to its convex roof which are below the linearized upper
bound. The zeros of the three-tangle (in this case) induced by the
zero-polytope (zero-simplex) are exact values. I apply this procedure to a
superposition of the four qubit GHZand W-state. It can however be applied to
every case one has under consideration, including an arbitrary polynomial
convex-roof measure of entanglement and for arbitrary local dimension.


title:
Time-Reversal-Symmetry-Breaking Superconductivity in Epitaxial
  Bismuth/Nickel Bilayers

abstract:
  Superconductivity that spontaneously breaks time-reversal symmetry (TRS) has
been found, so far, only in a handful of 3D crystals with bulk inversion
symmetry. Here we report an observation of spontaneous TRS breaking in a 2D
superconducting system without inversion symmetry: the epitaxial bilayer films
of bismuth and nickel. The evidence comes from the onset of the polar Kerr
effect at the superconducting transition in the absence of an external magnetic
field, detected by the ultrasensitive loop-less fiber-optic Sagnac
interferometer. Because of strong spin-orbit interaction and lack of inversion
symmetry in a Bi/Ni bilayer, superconducting pairing cannot be classified as
singlet or triplet. We propose a theoretical model where magnetic fluctuations
in Ni induce superconducting pairing of the dxy = +- idx^2y^2 orbital symmetry
between the electrons in Bi. In this model the order parameter spontaneously
breaks the TRS and has a non-zero phase winding number around the Fermi
surface, thus making it a rare example of a 2D topological superconductor.


title:
Shifted Chebyshev polynomials for Solving Three-Dimensional Volterra
  Integral Equations of the second kind

abstract:
  In this paper, an efficient method is presented for solving three dimensional
Volterra integral equations of the second kind with continuous kernel. Shifted
Chebyshev polynomial is applied to approximate a solution for these integral
equations. This method transforms the integral equation to algebraic equations
with unknown Chebyshev coefficients. Numerical results are calculated and the
estimated error in each example is computed using Maple 17.


title:
Josephson-phase-controlled interplay between correlation effects and
  electron pairing in a three-terminal nanostructure

abstract:
  We study the subgap spectrum of the interacting single-level quantum dot
coupled between two superconducting reservoirs, forming the Josephson-type
circuit, and additionally hybridized with a metallic normal lead. This system
allows for the phase-tunable interplay between the correlation effects and the
proximity-induced electron pairing resulting in the singlet-doublet (0-$\pi$)
crossover and the phase-dependent Kondo effect. We investigate the spectral
function, induced local pairing, Josephson supercurrent, and Andreev
conductance in a wide range of system parameters by the numerically exact
Numerical Renormalization Group and Quantum Monte Carlo calculations along with
perturbative treatments in terms of the Coulomb repulsion and the hybridization
term. Our results address especially the correlation effects reflected in
dependencies of various quantities on the local Coulomb interaction strength as
well as on the coupling to the normal lead. We quantitatively establish the
phase-dependent Kondo temperature $\log T_{K}(\phi)\propto\cos^{2}(\phi/2)$ and
show that it can be read off from the half-width of the zero-bias enhancement
in the Andreev conductance in the doublet phase, which can be experimentally
measured by the tunneling spectroscopy.


title: Novel phases in strongly coupled four-fermion theories

abstract:
  We study a lattice model comprising four massless reduced staggered fermions
in four dimensions coupled through an $SU(4)$-invariant four-fermion
interaction. We present both theoretical arguments and numerical evidence that
no bilinear fermion condensates are present for any value of the four-fermi
coupling, in contrast to earlier studies of Higgs--Yukawa models with different
exact lattice symmetries. At strong coupling we observe the formation of a
four-fermion condensate and a mass gap in spite of the absence of bilinear
condensates. Unlike those previously studied systems we do not find a
ferromagnetic phase separating this strong-coupling phase from the massless
weak-coupling phase. Instead we observe long-range correlations in a narrow
region of the coupling, still with vanishing bilinear condensates. While our
numerical results come from relatively small lattice volumes that call for
caution in drawing conclusions, if this novel phase structure is verified by
future investigations employing larger volumes it may offer the possibility for
new continuum limits for strongly interacting fermions in four dimensions.


title:
Maximal amenability of the generator subalgebra in $q$-Gaussian von
  Neumann algebras

abstract:
  In this article, we give explicit examples of maximal amenable subalgebras of
the $q$-Gaussian algebras, namely, the generator subalgebra is maximal amenable
inside the $q$-Gaussian algebras for real numbers $q$ with its absolute value
sufficiently small. To achieve this, we construct a Riesz basis in the spirit
of R\u{a}dulescu and develop a structural theorem for the $q$-Gaussian
algebras.


title:
Sustained Turbulence in Differentially Rotating Magnetized Fluids at Low
  Magnetic Prandtl Number

abstract:
  We show for the first time that sustained turbulence is possible at low
magnetic Prandtl number for Keplerian flows with no mean magnetic flux. Our
results indicate that increasing the vertical domain size is equivalent to
increasing the dynamical range between the energy injection scale and the
dissipative scale. This has important implications for a large variety of
differentially rotating systems with low magnetic Prandtl number such as
protostellar disks and laboratory experiments.


title: Difference Dimension Quasi-polynomials

abstract:
  We consider Hilbert-type functions associated with difference (not
necessarily inversive) field extensions and systems of algebraic difference
equations in the case when the translations are assigned some integer weights.
We will show that such functions are quasi-polynomials, which can be
represented as alternative sums of Ehrhart quasi-polynomials associated with
rational conic polytopes. In particular, we obtain generalizations of main
theorems on difference dimension polynomials and their invariants to the case
of weighted basic difference operators.


title: Squared Dehn twists and deformed symplectic invariants

abstract:
  We establish an infinitesimal version of fragility for squared Dehn twists
around even dimensional Lagrangian spheres. The precise formulation involves
twisting the Fukaya category by a closed two-form or bulk deforming it by a
half-dimensional cycle. As our main application, we compute the twisted and
bulk deformed symplectic cohomology of the subflexible Weinstein manifolds
constructed in \cite{murphysiegel}.


title: Shape Completion Enabled Robotic Grasping

abstract:
  This work provides an architecture to enable robotic grasp planning via shape
completion. Shape completion is accomplished through the use of a 3D
convolutional neural network (CNN). The network is trained on our own new open
source dataset of over 440,000 3D exemplars captured from varying viewpoints.
At runtime, a 2.5D pointcloud captured from a single point of view is fed into
the CNN, which fills in the occluded regions of the scene, allowing grasps to
be planned and executed on the completed object. Runtime shape completion is
very rapid because most of the computational costs of shape completion are
borne during offline training. We explore how the quality of completions vary
based on several factors. These include whether or not the object being
completed existed in the training data and how many object models were used to
train the network. We also look at the ability of the network to generalize to
novel objects allowing the system to complete previously unseen objects at
runtime. Finally, experimentation is done both in simulation and on actual
robotic hardware to explore the relationship between completion quality and the
utility of the completed mesh model for grasping.


title: Sharp commutator estimates via harmonic extensions

abstract:
  We give an alternative proof of several sharp commutator estimates involving
Riesz transforms, Riesz potentials, and fractional Laplacians. Our methods only
involve harmonic extensions to the upper half-space, integration by parts, and
trace space characterizations.
  The commutators we investigate are Jacobians, more generally
Coifman-Rochberg-Weiss commutators, Chanillo's commutator with the Riesz
potential, Coifman-Meyer or Kato-Ponce-Vega type commutators, and the Da
Lio-Rivi\`{e}re three-term commutators. We also give a new limiting
$L^1$-estimate for a double commutator of Coifman-Rochberg-Weiss-type, and
several intermediate estimates.
  The beauty of our method is that all those commutator estimates, which are
originally proven by various specific methods or by general paraproduct
arguments, can be obtained purely from integration by parts and trace theorems.
Another interesting feature is that in all these cases the cancellation effect
responsible for the commutator estimate simply follows from the product rule
for classical derivatives and can be traced in a precise way.


title: The magnetic properties of the hollow cylindrical ideal remanence magnet

abstract:
  We consider the magnetic properties of the hollow cylindrical ideal remanence
magnet. This magnet is the cylindrical permanent magnet that generates a
uniform field in the cylinder bore, using the least amount of magnetic energy
to do so. The remanence distribution of this magnet is derived and the
generated field is compared to that of a Halbach cylinder of equal dimensions.
The ideal remanence magnet is shown in most cases to generate a significantly
lower field than the equivalent Halbach cylinder, although the field is
generated with higher efficiency. The most efficient Halbach cylinder is shown
to generate a field exactly twice as large as the equivalent ideal remanence
magnet.


title:
Short average distribution of a prime counting function over families of
  elliptic curves

abstract:
  Let $E$ be an elliptic curve defined over $\mathbb{Q}$ and let $N$ be a
positive integer. Now, $M_E(N)$ counts the number of primes $p$ such that the
group $E_p(\mathbb{F}_p)$ is of order $N$. In an earlier joint work with
Balasubramanian, we showed that $M_E(N)$ follows Poisson distribution when an
average is taken over a family of elliptic curve with parameters $A$ and $B$
where $A,\, B\ge N^{\frac{\ell}{2}}(\log N)^{1+\gamma}$ and
$AB>N^{\frac{3\ell}{2}}(\log N)^{2+\gamma}$ for a fixed integer $\ell$ and any
$\gamma>0$. In this paper, we show that for sufficiently large $N$, the same
result holds even if we take $A$ and $B$ in the range
$\exp(N^{\frac{\epsilon^2}{20\ell}})\ge A, B>N^\epsilon$ and
$AB>N^{\frac{3\ell}{2}}(\log N)^{6+\gamma}$ for any $\epsilon>0$.


title: Correct classification for big/smart/fast data machine learning

abstract:
  Table (database) / Relational database Classification for big/smart/fast data
machine learning is one of the most important tasks of predictive analytics and
extracting valuable information from data. It is core applied technique for
what now understood under data science and/or artificial intelligence. Widely
used Decision Tree (Random Forest) and rare used rule based PRISM , VFST, etc
classifiers are empirical substitutions of theoretically correct to use Boolean
functions minimization. Developing Minimization of Boolean functions algorithms
is started long time ago by Edward Veitch's 1952. Since it, big efforts by wide
scientific/industrial community was done to find feasible solution of Boolean
functions minimization. In this paper we propose consider table data
classification from mathematical point of view, as minimization of Boolean
functions. It is shown that data representation may be transformed to Boolean
functions form and how to use known algorithms. For simplicity, binary output
function is used for development, what opens doors for multivalued outputs
developments.


title:
Disordered Route to the Coulomb Quantum Spin Liquid: Random Transverse
  Fields on Spin Ice in Pr$_2$Zr$_2$O$_7$

abstract:
  Inelastic neutron scattering reveals a broad continuum of excitations in
Pr$_2$Zr$_2$O$_7$, the temperature and magnetic field dependence of which
indicate a continuous distribution of quenched transverse fields ($\Delta$)
acting on the non-Kramers Pr$^{3+}$ crystal field ground state doublets.
Spin-ice correlations are apparent within 0.2 meV of the Zeeman energy. A
random phase approximation provides an excellent account of the data with a
transverse field distribution $\rho(\Delta)\propto (\Delta^2+\Gamma^2)^{-1}$
where $ \Gamma=0.27(1)$ meV. Established during high temperature synthesis due
to an underlying structural instability, it appears disorder in
Pr$_2$Zr$_2$O$_7$ actually induces a quantum spin liquid.


title:
Charge and Matter Form Factors of Two-Neutron Halo Nuclei in Halo
  Effective Field Theory at Next-to-leading-order

abstract:
  Using halo effective field theory (EFT), an expansion in $R_{core}/R_{halo}$,
where $R_{core}$ is the radius of the core and $R_{halo}$ the radius of the
halo nucleus, we calculate the charge and neutron form factors of the
two-neutron halo nuclei $^{11}$Li, $^{14}$Be, and $^{22}$C to
next-to-leading-order (NLO) by treating them as an effective three-body system.
From the form factors we extract the point charge and point matter radii,
inter-neutron distance, and neutron opening angle. Agreement is found with
existing experimental extractions. Results are given for the point charge and
point matter radii for arbitrary neutron core scattering effective range,
$\rho_{cn}$, that can be used for predictions once $\rho_{cn}$ is measured.
Estimates for $\rho_{cn}$ are also used to make NLO predictions. Finally, our
point charge radii are compared to other halo-EFT predictions, and setting the
core mass equal to the neutron mass our point charge radius is found to agree
with an analytical prediction in the unitary limit.


title:
SPT0346-52: Negligible AGN Activity in a Compact, Hyper-starburst Galaxy
  at z = 5.7

abstract:
  We present Chandra ACIS-S and ATCA radio continuum observations of the
strongly lensed dusty, star-forming galaxy SPT-S J034640-5204.9 (hereafter
SPT0346-52) at $z$ = 5.656. This galaxy has also been observed with ALMA, HST,
Spitzer, Herschel, APEX, and the VLT. Previous observations indicate that if
the infrared (IR) emission is driven by star formation, then the inferred
lensing-corrected star formation rate ($\sim$ 4500 $M_{\sun}$ yr$^{-1}$) and
star formation rate surface density $\Sigma_{\rm SFR}$ ($\sim$ 2000 $M_{\sun}
{yr^{-1}} {kpc^{-2}}$) are both exceptionally high. It remained unclear from
the previous data, however, whether a central active galactic nucleus (AGN)
contributes appreciably to the IR luminosity. The {\it Chandra} upper limit
shows that SPT0346-52 is consistent with being star-formation dominated in the
X-ray, and any AGN contribution to the IR emission is negligible. The ATCA
radio continuum upper limits are also consistent with the FIR-to-radio
correlation for star-forming galaxies with no indication of an additional AGN
contribution. The observed prodigious intrinsic IR luminosity of (3.6 $\pm$
0.3) $\times$ 10$^{13}$ $L_{\sun}$ originates almost solely from vigorous star
formation activity. With an intrinsic source size of 0.61 $\pm$ 0.03 kpc,
SPT0346-52 is confirmed to have one of the highest $\Sigma_{SFR}$ of any known
galaxy. This high $\Sigma_{SFR}$, which approaches the Eddington limit for a
radiation pressure supported starburst, may be explained by a combination of
very high star formation efficiency and gas fraction.


title: The features of the Cosmic Web unveiled by the flip-flop field

abstract:
  Understanding of the observed structure in the universe can be reached only
in the theoretical framework of dark matter. N-body simulations are
indispensable for the analysis of the formation and evolution of the dark
matter web. Two primary fields - density and velocity fields - are used in most
of studies. However dark matter provides two additional fields which are unique
for collisionless media only. These are the multi- stream field in Eulerian
space and flip-flop field in Lagrangian space. The flip-flop field represents
the number of sign reversals of an elementary volume of each collisionless
fluid element. This field can be estimated by counting the sign reversals of
the Jacobian at each particle at every time step of the simulation. The
Jacobian is evaluated by numerical differentiation of the Lagrangian
submanifold, i.e., the three-dimensional dark matter sheet in the
six-dimensional space formed by three Lagrangian and three Eulerian
coordinates. We present the results of the statistical study of the evolution
of the flip-flop field from z = 50 to the present time z = 0. A number of
statistical characteristics show that the pattern of the flip-flop field
remains remarkably stable from z = 30 to the present time. As a result the
flip-flop field evaluated at z = 0 stores a wealth of information about the
dynamical history of the dark matter web. In particular one of the most
intriguing properties of the flip-flop is a unique capability to preserve the
information about the merging history of dark matter haloes.


title: Geometry induced phase transitions in magnetic spherical shell

abstract:
  Equilibrium magnetization states in thin spherical shells of a magnetically
soft ferromagnet are determined by the competition between two interactions:
(i) The local exchange interaction favours the more homogeneous onion state
with magnetization oriented in meridian directions; such a state is realized in
relatively small particles. (ii) The nonlocal magnetostatic interaction prefers
the double-vortex configuration with the magnetization oriented in the
parallels directions, since it minimizes the volume magnetostatic charges.
These sates are topologically equivalent, in contrast to the same-name states
of magnetic nanoring. As a consequence, a continuous (the second order) phase
transition between the vortex and onion states takes place. The detailed
analytical description of the phase diagram is well confirmed by micromagnetic
simulations.


title: Many-body methods in agent-based epidemic models

abstract:
  The susceptible-infected-susceptible (SIS) agent-based model is usually
employed in the investigation of epidemics. The model describes a Markov
process for a single communicable disease among susceptible (S) and infected
(I) agents. However, the disease spreading forecasting is often restricted to
numerical simulations, while analytic formulations lack both general results
and perturbative approaches since they are subjected to asymmetric time
generators. Here, we discuss perturbation theory, approximations and
application of many-body techniques in epidemic models in the framework for
squared norm of probability vector $|P(t)| ^2$, in which asymmetric time
generators are replaced by their symmetric counterparts.


title: Learning about stars from their colors

abstract:
  We pose the question of how much information on the atmospheric parameters of
late-type stars can be retrieved purely from colors using standard photometric
systems. We carried out numerical experiments using stellar fluxes from model
atmospheres, injecting random noise before analyzing them. We examined the
presence of degeneracies among atmospheric parameters, and evaluated how well
the parameters are extracted depending on the number and wavelength span of the
photometric filters available, from the UV GALEX to the mid-IR WISE passbands.
We also considered spectrophotometry from the Gaia mission. We find that
stellar effective temperatures can be determined accurately ($\sigma \sim$ 0.01
dex or about 150 K) when reddening is negligible or known, based merely on
optical photometry, and the accuracy can be improved twofold by including IR
data. On the other hand, stellar metallicities and surface gravities are fairly
unconstrained from optical or IR photometryy. However, our ability to retrieve
these parameters can improve significantly by adding UV photometry. When
reddening is considered a free parameter, assuming it can be modeled perfectly,
our experiments suggest that it can be disentangled from the rest of the
parameters. This theoretical study indicates that combining broad-band
photometry from the UV to the mid-IR allows atmospheric parameters and
interstellar extinction to be determined with fair accuracy. The use of UV
passbands helps substantially to derive metallicities and surface gravities, as
well as to break the degeneracy between effective temperature and reddening.
The Gaia BP/RP data can disentangle all the parameters, provided the stellar
SEDs are modeled reasonably well.


title:
First flight of the Gamma-Ray Imager/Polarimeter for Solar flares
  (GRIPS) instrument

abstract:
  The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) is a balloon-borne
telescope designed to study solar-flare particle acceleration and transport. We
describe GRIPS's first Antarctic long-duration flight in Jan 2016 and report
preliminary calibration and science results.
  Electron and ion dynamics, particle abundances and the ambient plasma
conditions in solar flares can be understood by examining hard X-ray (HXR) and
gamma-ray emission (20 keV to 10 MeV) with enhanced imaging, spectroscopy and
polarimetry. GRIPS is specifically designed to answer questions including: What
causes the spatial separation between energetic electrons producing HXRs and
energetic ions producing gamma-ray lines? How anisotropic are the relativistic
electrons, and why can they dominate in the corona? How do the compositions of
accelerated and ambient material vary with space and time, and why?
  GRIPS's key technological improvements over the Reuven Ramaty High Energy
Solar Spectroscopic Imager (RHESSI) include 3D position-sensitive germanium
detectors (3D-GeDs) and a single-grid, multi-pitch rotating modulator (MPRM)
collimator. The 3D-GeDs have spectral FWHM resolution of a few hundred keV and
spatial resolution $<$1 mm$^3$. For photons that Compton scatter, usually
$\gtrsim$150 keV, the energy deposition sites can be tracked, providing
polarization measurements as well as enhanced background reduction. The MPRM
single-grid design provides twice the throughput of a bi-grid imaging system
like RHESSI. The grid is composed of 2.5 cm thick W/Cu slats with 1-13 mm
variable slit pitch, achieving quasi-continuous FWHM angular coverage over
12.5-162 arcsecs. This resolution is capable of imaging the separate magnetic
loop footpoint emissions in a variety of flare sizes.
  (Abstract edited down from source.)

categories: astro-ph.IM astro-ph.HE astro-ph.SR physics.ins-det physics.space-ph


title: Stochastic resonance in a tristable optomechanical system

abstract:
  In this work we theoretically investigate the stochastic resonance (SR)
effect in an optomechanical membrane system subject to two weak signals (one
optical field and one mechanical force). The quadratic optomechanical coupling
allows us to find a region with tristability where the noise activated
stochastic switching among three stable states occurs and SR phenomena are
observed at the cooperation of input signals and noises. We show that the
mechanical force and the optical field respectively serve as an additive signal
and a multiplicative signal to the membrane position and they induce completely
different SR behaviors. Moreover, when two signals coexist the SR effect can be
enhanced and the beating effect appears in the SR synchronization process with
unsynchronized signals.


title: Integrability in out-of-equilibrium systems

abstract:
  This short note presents a summary of the articles arXiv:1408.5357,
arXiv:1412.5939, arXiv:1603.06796, arXiv:1606.01018, arXiv:1606.08148 that were
done in collaboration with N. CRAMPE, M. EVANS, C. FINN, K. MALLICK and M.
VANICAT. It presents an approach to the matrix ansatz of out-of-equilibrium
systems with boundaries, within the framework of integrable systems, and was
presented at ISQS24 (Prague, 2016).


title: Formulas for Generalized Two-Qubit Separability Probabilities

abstract:
  To begin, we find certain formulas $Q(k,\alpha)= G_1^k(\alpha)
G_2^k(\alpha)$, for $k = -1, 0, 1,...,9$. These yield that part of the total
separability probability, $P(k,\alpha)$, for generalized (real, complex,
quaternionic,\ldots) two-qubit states endowed with random induced measure, for
which the determinantal inequality $|\rho^{PT}| >|\rho|$ holds. Here $\rho$
denotes a $4 \times 4$ density matrix, obtained by tracing over the pure states
in $4 \times (4 +k)$-dimensions, and $\rho^{PT}$, its partial transpose.
Further, $\alpha$ is a Dyson-index-like parameter with $\alpha = 1$ for the
standard (15-dimensional) convex set of (complex) two-qubit states. For $k=0$,
we obtain the previously reported Hilbert-Schmidt formulas, with (the real
case) $Q(0,\frac{1}{2}) = \frac{29}{128}$, (the standard complex case)
$Q(0,1)=\frac{4}{33}$, and (the quaternionic case) $Q(0,2)=
\frac{13}{323}$---the three simply equalling $ P(0,\alpha)/2$. The factors
$G_2^k(\alpha)$ are sums of polynomial-weighted generalized hypergeometric
functions $_{p}F_{p-1}$, $p \geq 7$, all with argument $z=\frac{27}{64}
=(\frac{3}{4})^3$. We find number-theoretic-based formulas for the upper
($u_{ik}$) and lower ($b_{ik}$) parameter sets of these functions and, then,
equivalently express $G_2^k(\alpha)$ in terms of first-order difference
equations. Applications of Zeilberger's algorithm yield "concise" forms,
parallel to the one obtained previously for $P(0,\alpha) =2 Q(0,\alpha)$. For
nonnegative half-integer and integer values of $\alpha$, $Q(k,\alpha)$ has
descending roots starting at $k=-\alpha-1$. Then, we (C. Dunkl and I) construct
a remarkably compact (hypergeometric) form for $Q(k,\alpha)$ itself. The
possibility of an analogous "master" formula for $P(k,\alpha)$ is, then,
investigated, and a number of interesting results found.


title:
Security of two-state and four-state practical quantum bit-commitment
  protocols

abstract:
  We study cheating strategies against a practical four-state quantum
bit-commitment protocol and its two-state variant when the underlying quantum
channels are noisy and the cheating party is constrained to using single-qubit
measurements only. We show that simply inferring the transmitted photons'
states by using the Breidbart basis, optimal for ambiguous (minimum-error)
state discrimination, does not directly produce an optimal cheating strategy
for this bit-commitment protocol. We introduce a new strategy, based on certain
post-measurement processes, and show it to have better chances at cheating than
the direct approach. We also study to what extent sending forged geographical
coordinates helps a dishonest party in breaking the binding security
requirement. Finally, we investigate the impact of imperfect single-photon
sources in the protocols. Our study shows that, in terms of the resources used,
the four-state protocol is advantageous over the two-state version. The
analysis performed can be straightforwardly generalised to any finite-qubit
measurement, with the same qualitative results.


title: New limits on neutrino magnetic moments from low energy neutrino data

abstract:
  Here we give a brief review on the current bounds on the general Majorana
transition neutrino magnetic moments (TNMM) which cover also the conventional
neutrino magnetic moments (NMM). Leptonic CP phases play a key role in
constraining TNMMs. While the Borexino experiment is the most sensitive to the
TNMM magnitudes, one needs complementary information from reactor and
accelerator experiments in order to probe the complex CP phases.


title: Output Feedback Control of the One-Phase Stefan Problem

abstract:
  In this paper, a backstepping observer and an output feedback control law are
designed for the stabilization of the one-phase Stefan problem. The present
result is an improvement of the recent full state feedback backstepping
controller proposed in our previous contribution. The one-phase Stefan problem
describes the time-evolution of a temperature profile in a liquid-solid
material and its liquid-solid moving interface. This phase transition problem
is mathematically formulated as a 1-D diffusion Partial Differential Equation
(PDE) of the melting zone defined on a time-varying spatial domain described by
an Ordinary Differential Equation (ODE). We propose a backstepping observer
allowing to estimate the temperature profile along the melting zone based on
the available measurement, namely, the solid phase length. The designed
observer and the output feedback controller ensure the exponential stability of
the estimation errors, the moving interface, and the ${\cal H}_1$-norm of the
distributed temperature while keeping physical constraints, which is shown with
the restriction on the gain parameter of the observer and the setpoint.


title:
Carbon nanofiber-filled conductive silicone elastomers as soft, dry
  bioelectronic interfaces

abstract:
  Soft and pliable conductive polymer composites hold promise for application
as bioelectronic interfaces such as for electroencephalography (EEG). In
clinical, laboratory, and real-world EEG there is a desire for dry, soft, and
comfortable interfaces to the scalp that are capable of relaying the
microvolt-level scalp potentials to signal processing electronics. A key
challenge is that most material approaches are sensitive to deformation-induced
shifts in electrical impedance associated with decreased signal-to-noise ratio.
This is a particular concern in real-world environments where human motion is
present. The entire set of brain information outside of tightly controlled
laboratory or clinical settings are currently unobtainable due to this
challenge. Here we explore the performance of an elastomeric material solution
purposefully designed for dry, soft, comfortable scalp contact electrodes for
EEG that is specifically targeted to have flat electrical impedance response to
deformation to enable utilization in real world environments. A conductive
carbon nanofiber filled polydimethylsiloxane (CNF-PDMS) elastomer was evaluated
at three fill ratios (3, 4 and 7 volume percent). To evaluate usability for
EEG, pre-recorded human EEG signals were replayed through the contact
electrodes subjected to quasi-static compressive strains between zero and 35%.
These tests show that conductive filler ratios well above the electrical
percolation threshold are desirable in order to maximize signal-to-noise ratio
and signal correlation with an ideal baseline. Increasing fill ratios yield
increasingly flat electrical impedance response to large applied compressive
deformations with a trade in increased material stiffness, and with nominal
electrical impedance tunable over greater than 4 orders of magnitude.


title: Optical conductivity of multi-Weyl semimetals

abstract:
  Multi-Weyl semimetals are new types of Weyl semimetals which have anisotropic
non-linear energy dispersion and a topological charge larger than one, thus
exhibiting a unique quantum response. Using a unified lattice model, we
calculate the optical conductivity numerically in the multi-Weyl semimetal
phase and in its neighboring gapped states, and obtain the characteristic
frequency dependence of each phase analytically using a low-energy continuum
model. The frequency dependence of longitudinal and transverse optical
conductivities obeys scaling relations that are derived from the winding number
of the parent multi-Weyl semimetal phase and can be used to distinguish these
electronic states of matter.


title:
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray
  spectrum

abstract:
  We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at $\lg(E/{\rm eV})=18.5-19.0$ differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass $A >
4$. Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.


title: Non-properly Embedded H-Planes in H^2xR

abstract:
  For any $H$ in (0,1/2), we construct complete, non-proper, stable,
simply-connected surfaces embedded in $H^2xR$ with constant mean curvature $H$.


title:
The Hierarchical Spectral Merger algorithm: A New Time Series Clustering
  Procedure

abstract:
  We present a new method for time series clustering which we call the
Hierarchical Spectral Merger (HSM) method. This procedure is based on the
spectral theory of time series and identifies series that share similar
oscillations or waveforms. The extent of similarity between a pair of time
series is measured using the total variation distance between their estimated
spectral densities. At each step of the algorithm, every time two clusters
merge, a new spectral density is estimated using the whole information present
in both clusters, which is representative of all the series in the new cluster.
The method is implemented in an R package HSMClust. We present two applications
of the HSM method, one to data coming from wave-height measurements in
oceanography and the other to electroencefalogram (EEG) data.


title:
Potentially semi-stable deformations of specified Hodge-Tate type and
  Galois type

abstract:
  Let $k$ be a perfect field of characteristic $p > 2$, and let $K$ be a finite
totally ramified extension of $W(k)[\frac{1}{p}]$. We prove that the locus of
potentially semi-stable $\mathrm{Gal}(\bar{K}/K)$-representations of a given
Hodge-Tate type and Galois type is a closed subspace of the universal
deformation ring, generalizing the result of Kisin (2007) where $k$ is assumed
to be finite.


title:
Analysis and limitations of modified circuit-to-Hamiltonian
  constructions

abstract:
  Feynman's circuit-to-Hamiltonian construction connects quantum computation
and ground states of many-body quantum systems. Kitaev applied this
construction to demonstrate QMA-completeness of the local Hamiltonian problem,
and Aharanov et al. used it to show the equivalence of adiabatic computation
and the quantum circuit model. In this work, we analyze the low energy
properties of a class of modified circuit Hamiltonians, which include features
like complex weights and branching transitions. For history states with linear
clocks and complex weights, we develop a method for modifying the circuit
propagation Hamiltonian to implement any desired distribution over the time
steps of the circuit in a frustration-free ground state, and show that this can
be used to obtain a constant output probability for universal adiabatic
computation while retaining the $\Omega(T^{-2})$ scaling of the spectral gap,
and without any additional overhead in terms of numbers of qubits.
  Furthermore, we establish limits on the increase in the ground energy due to
input and output penalty terms for modified tridiagonal clocks with non-uniform
distributions on the time steps by proving a tight $O(T^{-2})$ upper bound on
the product of the spectral gap and ground state overlap with the endpoints of
the computation. Using variational techniques which go beyond the
$\Omega(T^{-3})$ scaling that follows from the usual geometrical lemma, we
prove that the standard Feynman-Kitaev Hamiltonian already saturates this
bound. We review the formalism of unitary labeled graphs which replace the
usual linear clock by graphs that allow branching and loops, and we extend the
$O(T^{-2})$ bound from linear clocks to this more general setting. In order to
achieve this, we apply Chebyshev polynomials to generalize an upper bound on
the spectral gap in terms of the graph diameter to the context of arbitrary
Hermitian matrices.


title: Dipole of the Epoch of Reionization 21-cm signal

abstract:
  The motion of the solar system with respect to the cosmic rest frame
modulates the monopole of the Epoch of Reionization 21-cm signal into a dipole.
This dipole has a characteristic frequency dependence that is dominated by the
frequency derivative of the monopole signal. We argue that although the signal
is weaker by a factor of $\sim100$, there are significant benefits in measuring
the dipole. Most importantly, the direction of the cosmic velocity vector is
known exquisitely well from the cosmic microwave background and is not aligned
with the galaxy velocity vector that modulates the foreground monopole.
Moreover, an experiment designed to measure a dipole can rely on differencing
patches of the sky rather than making an absolute signal measurement, which
helps with some systematic effects.


title: Noise induced phase transition in the $S$-state block voter model

abstract:
  We use Monte Carlo simulations and finite-size scaling theory to investigate
the phase transition and critical behavior of the $S$-state block voter model
on square lattices. It is shown that the system exhibits an order-disorder
phase transition at a given value of the noise parameter, which changes from a
continuous transition for $S\le4$ to a discontinuous transition for $S\ge5$.
Moreover, for the cases of continuous transition, the calculated critical
exponents indicate that the present studied nonequilibrium model system is in
the same universality class of its counterpart equilibrium two-dimensional
S-state Potts model. We also provide a first estimation of the long-range
exponents governing the dependence on the range of interaction of the
magnetization, the susceptibility, and the derivative of Binder's cumulant.


title:
Asynchronous progress design for a MPI-based PGAS one-sided
  communication system

abstract:
  Remote-memory-access models, also known as one-sided communication models,
are becoming an interesting alternative to traditional two-sided communication
models in the field of High Performance Computing. In this paper we extend
previous work on an MPI-based, locality-aware remote-memory-access model with a
asynchronous progress-engine for non-blocking communication operations. Most
previous related work suggests to drive progression on communication through an
additional thread within the application process. In contrast, our scheme uses
an arbitrary number of dedicated processes to drive asynchronous progression.
Further, we describe a prototypical library implementation of our concepts,
namely DART, which is used to quantitatively evaluate our design against a
MPI-3 baseline reference. The evaluation consists of micro-benchmark to measure
overlap of communication and computation and a scientific application kernel to
assess total performance impact on realistic use-cases. Our benchmarks shows,
that our asynchronous progression scheme can overlap computation and
communication efficiently and lead to substantially shorter communication cost
in real applications.


title: Painlev\'e IV and a third-order viewpoint

abstract:
  We take a third-order approach to the fourth Painlev\'e equation and indicate
the value of such an approach to other second-order ODEs in the
Painlev\'e-Gambier list of 50.


title: The Linear Growth of Structure in the R_h=ct Universe

abstract:
  We use recently published redshift space distortion measurements of the
cosmological growth rate, f sigma_8(z), to examine whether the linear evolution
of perturbations in the R_h=ct cosmology is consistent with the observed
development of large scale structure. We find that these observations favour
R_h=ct over the version of LCDM optimized with the joint analysis of Planck and
linear growth rate data, particularly in the redshift range 0 < z < 1, where a
significant curvature in the functional form of f sigma_8(z) predicted by the
standard model---but not by R_h=ct---is absent in the data. When LCDM is
optimized using solely the growth rate measurements, however, the two models
fit the observations equally well though, in this case, the low-redshift
measurements find a lower value for the fluctuation amplitude than is expected
in Planck LCDM. Our results strongly affirm the need for more precise
measurements of f sigma_8(z) at all redshifts, but especially at z < 1.


title:
Phase- and intensity-dependence of ultrafast dynamics in hydrocarbon
  molecules in few-cycle laser fields

abstract:
  In strong laser fields, sub-femtosecond control of chemical reactions with
the carrier-envelope phase (CEP) becomes feasible. We have studied the control
of reaction dynamics of acetylene and allene in intense few-cycle laser pulses
at 750 nm, where ionic fragments are recorded with a reaction microscope. We
find that by varying the CEP and intensity of the laser pulses it is possible
to steer the motion of protons in the molecular dications, enabling control
over deprotonation and isomerization reactions. The experimental results are
compared to predictions from a quantum dynamical model, where the control is
based on the manipulation of the phases of a vibrational wave packet by the
laser waveform. The measured intensity dependence in the CEP-controlled
deprotonation of acetylene is well captured by the model. In the case of the
isomerization of acetylene, however, we find differences in the intensity
dependence between experiment and theory. For the isomerization of allene, an
inversion of the CEP-dependent asymmetry is observed when the intensity is
varied, which we discuss in light of the quantum dynamical model. The inversion
of the asymmetry is found to be consistent with a transition from
non-sequential to sequential double ionization.


title: Arithmetic properties for cubic partition pairs modulo powers of 3

abstract:
  Let $b(n)$ denote the number of cubic partition pairs of $n$. In this paper,
we aim to provide a strategy to obtain arithmetic properties of $b(n)$. This
gives affirmative answers to two of Lin's conjectures.


title: Markovian Marignals

abstract:
  We introduce a class of so called Markovian marginals, which gives a natural
framework for constructing solutions to the quantum marginal problem. We
consider a set of marginals that possess a certain internal quantum Markov
chain structure. If they are equipped with such a structure and are locally
consistent on their overlapping supports, there exists a global state that is
consistent with all the marginals. The proof is constructive, and relies on a
reduction of the marginal problem to a certain combinatorial problem. By
employing an entanglement entropy scaling law, we give a physical argument that
the requisite structure exists in any states with finite correlation lengths.
This includes topologically ordered states as well as finite temperature Gibbs
states.

categories: quant-ph cond-mat.str-el math-ph math.MP


title: Gravitational focusing of Imperfect Dark Matter

abstract:
  Motivated by the projectable Horava--Lifshitz model/mimetic matter scenario,
we consider a particular modification of standard gravity, which manifests as
an imperfect low pressure fluid. While practically indistinguishable from a
collection of non-relativistic weakly interacting particles on cosmological
scales, it leaves drastically different signatures in the Solar system. The
main effect stems from gravitational focusing of the flow of Imperfect Dark
Matter passing near the Sun. This entails strong amplification of Imperfect
Dark Matter energy density compared to its average value in the surrounding
halo. The enhancement is many orders of magnitude larger than in the case of
Cold Dark Matter, provoking deviations of the metric in the second order in the
Newtonian potential. Effects of gravitational focusing are prominent enough to
substantially affect the planetary dynamics. Using the existing bound on the
PPN parameter $\beta_{PPN}$, we deduce a stringent constraint on the unique
constant of the model.


title: A Probability Density Function for Neutrino Masses and Mixings

abstract:
  The anarchy principle leading to the see-saw ensemble is studied analytically
with the usual tools of random matrix theory. The probability density function
for the see-saw ensemble of $N\times N$ matrices is obtained in terms of a
multidimensional integral. This integral involves all light neutrino masses,
leading to a complicated probability density function. It is shown that the
probability density function for the neutrino mixing angles and phases is the
appropriate Haar measure. The decoupling of the light neutrino masses and
neutrino mixings implies no correlation between the neutrino mass eigenstates
and the neutrino mixing matrix and leads to a loss of predictive power when
comparing with observations. This decoupling is in agreement with some of the
claims found in the literature.


title:
The two-dimensional Coulomb plasma: quasi-free approximation and central
  limit theorem

abstract:
  For the two-dimensional one-component Coulomb plasma, we derive an asymptotic
expansion of the free energy up to order $N$, the number of particles of the
gas, with an effective error bound $N^{1-\kappa}$ for some constant $\kappa >
0$. This expansion is based on approximating the Coulomb gas by a quasi-free
Yukawa gas. Further, we prove that the fluctuations of the linear statistics
are given by a Gaussian free field at any positive temperature. Our proof of
this central limit theorem uses a loop equation for the Coulomb gas, the free
energy asymptotics, and rigidity bounds on the local density fluctuations of
the Coulomb gas, which we obtained in a previous paper.


title:
Survey of Inter-satellite Communication for Small Satellite Systems:
  Physical Layer to Network Layer View

abstract:
  Small satellite systems enable whole new class of missions for navigation,
communications, remote sensing and scientific research for both civilian and
military purposes. As individual spacecraft are limited by the size, mass and
power constraints, mass-produced small satellites in large constellations or
clusters could be useful in many science missions such as gravity mapping,
tracking of forest fires, finding water resources, etc. Constellation of
satellites provide improved spatial and temporal resolution of the target.
Small satellite constellations contribute innovative applications by replacing
a single asset with several very capable spacecraft which opens the door to new
applications. With increasing levels of autonomy, there will be a need for
remote communication networks to enable communication between spacecraft. These
space based networks will need to configure and maintain dynamic routes, manage
intermediate nodes, and reconfigure themselves to achieve mission objectives.
Hence, inter-satellite communication is a key aspect when satellites fly in
formation. In this paper, we present the various researches being conducted in
the small satellite community for implementing inter-satellite communications
based on the Open System Interconnection (OSI) model. This paper also reviews
the various design parameters applicable to the first three layers of the OSI
model, i.e., physical, data link and network layer. Based on the survey, we
also present a comprehensive list of design parameters useful for achieving
inter-satellite communications for multiple small satellite missions. Specific
topics include proposed solutions for some of the challenges faced by small
satellite systems, enabling operations using a network of small satellites, and
some examples of small satellite missions involving formation flying aspects.


title: Asymmetric de Finetti Theorem for Infinite-dimensional Quantum Systems

abstract:
  The de Finetti representation theorem for continuous variable quantum system
is first developed to approximate an N-partite continuous variable quantum
state with a convex combination of independent and identical subsystems, which
requires the original state to obey permutation symmetry conditioned on
successful experimental verification on k of N subsystems. We generalize the de
Finetti theorem to include asymmetric bounds on the variance of canonical
observables and biased basis selection during the verification step. Our result
thereby enables application of infinite-dimensional de Finetti theorem to
situations where two conjugate measurements obey different statistics, such as
the security analysis of quantum key distribution protocols based on squeezed
state against coherent attack.


title: Finite-Dimensional Representations constructed from Random Walks

abstract:
  Given a $1$-cocycle $b$ with coefficients in an orthogonal representation, we
show that any finite dimensional summand of $b$ is cohomologically trivial if
and only if $\| b(X_n) \|^2/n$ tends to a constant in probability, where $X_n$
is the trajectory of the random walk $(G,\mu)$. As a corollary, we obtain
sufficient conditions for $G$ to satisfy Shalom's property $H_{\mathrm{FD}}$.
Another application is a convergence to a constant in probability of
$\mu^{*n}(e) -\mu^{*n}(g)$, $n\gg m$, normalized by its average with respect to
$\mu^{*m}$, for any finitely generated amenable group without infinite
virtually Abelian quotients. Finally, we show that the harmonic equivariant
mapping of $G$ to a Hilbert space obtained as an $U$-ultralimit of normalized
$\mu^{*n}- g \mu^{*n}$ can depend on the ultrafilter $U$ for some groups.


title:
Determination of the proton-to-helium ratio in cosmic rays at ultra-high
  energies from the tail of the $X_{\rm max}$ distribution

abstract:
  We present a method to determine the proton-to-helium ratio in cosmic rays at
ultra-high energies. It makes use of the exponential slope, $\Lambda$, of the
tail of the $X_{\rm max}$ distribution measured by an air shower experiment.
The method is quite robust with respect to uncertainties from modeling hadronic
interactions and to systematic errors on $X_{\rm max}$ and energy, and to the
possible presence of primary nuclei heavier than helium. Obtaining the
proton-to-helium ratio with air shower experiments would be a remarkable
achievement.
  To quantify the applicability of a particular mass-sensitive variable for
mass composition analysis despite hadronic uncertainties we introduce as a
metric the `analysis indicator' and find an improved performance of the
$\Lambda$ method compared to other variables currently used in the literature.
The fraction of events in the tail of the $X_{\rm max}$ distribution can
provide additional information on the presence of nuclei heavier than helium in
the primary beam.


title: Lowest Landau level on a cone and zeta determinants

abstract:
  We consider the integer QH state on Riemann surfaces with conical
singularities, with the main objective of detecting the effect of the
gravitational anomaly directly from the form of the wave function on a singular
geometry. We suggest the formula expressing the normalisation factor of the
holomorphic state in terms of the regularized zeta determinant on conical
surfaces and check this relation for some model geometries. We also comment on
possible extensions of this result to the fractional QH states.


title: Efficient Algorithms for Scheduling Moldable Tasks

abstract:
  We study the problem of scheduling $n$ independent moldable tasks on $m$
processors that arises in large-scale parallel computations. When tasks are
monotonic, the best known result is a $(\frac{3}{2}+\epsilon)$-approximation
algorithm for makespan minimization with a complexity linear in $n$ and
polynomial in $\log{m}$ and $\frac{1}{\epsilon}$ where $\epsilon$ is
arbitrarily small. We propose a new perspective of the existing speedup models:
the speedup of a task $T_{j}$ is linear when the number $p$ of assigned
processors is small (up to a threshold $\delta_{j}$) while it presents
monotonicity when $p$ ranges in $[\delta_{j}, k_{j}]$; the bound $k_{j}$
indicates an unacceptable overhead when parallelizing on too many processors.
For a given integer $\delta\geq 5$, let $u=\left\lceil \sqrt[2]{\delta}
\right\rceil-1$. In this paper, we propose a $\frac{1}{\theta(\delta)}
(1+\epsilon)$-approximation algorithm for makespan minimization with a
complexity $\mathcal{O}(n\log{\frac{n}{\epsilon}}\log{m})$ where
$\theta(\delta) = \frac{u+1}{u+2}\left( 1- \frac{k}{m} \right)$ ($m\gg k$). As
a by-product, we also propose a $\theta(\delta)$-approximation algorithm for
throughput maximization with a common deadline with a complexity
$\mathcal{O}(n^{2}\log{m})$.


title: Sewing Greenberger-Horne-Zeilinger states with a quantum zipper

abstract:
  A mechanism of a chiral spin wave rotation is introduced to systematically
generate mesoscopic Greenberger-Horne-Zeilinger states.


title: A Lower Bound on the Renormalized Nelson Model

abstract:
  We provide explicit lower bounds for the ground-state energy of the
renormalized Nelson model in terms of the coupling constant $\alpha$ and the
number of particles $N$, uniform in the meson mass and valid even in the
massless case. In particular, for any number of particles $N$ and large enough
$\alpha$ we provide a bound of the form $-C\alpha^2 N^3\log^2(\alpha N)$, where
$C$ is an explicit positive numerical constant; and if $\alpha$ is sufficiently
small, we give one of the form $-C\alpha^2 N^3\log^2 N$ for $N \geq 2$, and
$-C\alpha^2$ for $N = 1$. Whereas it is known that the renormalized Hamiltonian
of the Nelson model is bounded below (as realized by E. Nelson) and implicit
lower bounds have been given elsewhere (as in a recent work by Gubinelli,
Hiroshima, and L\"{o}rinczi), ours seem to be the first fully explicit lower
bounds with a reasonable dependence on $\alpha$ and $N$. We emphasize that the
logarithmic term in the bounds above is probably an artifact in our
calculations, since one would expect that the ground-state energy should behave
as $-C\alpha^2 N^3$ for large $N$ or $\alpha$, as in the polaron model of H.
Fr\"{o}hlich.


title:
The $C \: ^1 \Sigma ^+$, $A \: ^1 \Sigma ^+$, and $b \: ^3 \Pi_{0^+}$
  states of LiRb

abstract:
  We present the first spectroscopic studies of the $C \ ^1\Sigma^+$ electronic
state and the $A \ ^1\Sigma^+$ - $b \ ^3\Pi_{0^+}$ complex in $^7$Li -
$^{85}$Rb. Using resonantly-enhanced, two-photon ionization, we observed $v =
7$, 9, 12, 13 and $26-44$ of the $C \ ^1\Sigma^+$ state. We augment the REMPI
data with a form of depletion spectra in regions of dense spectral lines. The
$A \ ^1\Sigma^+$ - $b \ ^3\Pi_{0^+}$ complex was observed with depletion
spectroscopy, depleting to vibrational levels $v=0 \rightarrow 29$ of the $A \
^1\Sigma^+$ state and $v=8 \rightarrow 18$ of the $b \ ^3\Pi_{0^+}$ state. For
all three series, we determine the term energy and vibrational constants.
Finally, we outline several possible future projects based on the data
presented here.


title:
Additive Classical Capacity of Quantum Channels Assisted by Noisy
  Entanglement

abstract:
  We give a capacity formula for the classical information transmission over a
noisy quantum channel, with separable encoding by the sender and limited
resources provided by the receiver's pre-shared ancilla. Instead of a pure
state, we consider the signal-ancilla pair in a mixed state, purified by a
"witness". Thus, the signal-witness correlation limits the resource available
from the signal-ancilla correlation. Our formula characterizes the utility of
different forms of resources, including noisy or limited entanglement
assistance, for classical communication. With separable encoding, the sender's
signals across multiple channel uses are still allowed to be entangled, yet our
capacity formula is additive. In particular, for generalized covariant channels
our capacity formula has a simple closed-form. Moreover, our additive capacity
formula upper bounds the general coherent attack's information gain in various
two-way quantum key distribution protocols. For Gaussian protocols, the
additivity of the formula indicates that the collective Gaussian attack is the
most powerful.


title: Multi-graded nilpotent tuples

abstract:
  We discuss multi-graded nilpotent tuples of multi-graded vector spaces which
are a generalization of graded nilpotent pairs. The multi-grading yields a
natural notion of a shape of such tuple and our main interest is to answer the
question "Is the number of multi-graded nilpotent tuples of a fixed shape, up
to base change in the homogeneous components, finite?" Our methods make use of
a translation to the class of so-called "Multi-staircase algebras" and we
classify their representation types.


title: Capacity Estimates via comparison with TRO channels

abstract:
  A ternary ring of operators (TRO) in finite dimensions is a diagonal sum of
spaces of rectangular matrices. TRO as operator space corresponds to quantum
channels that are diagonal sums of partial traces, which we call TRO channels.
TRO channels admits simple, single-letter capacity formula. Using operator
space and complex interpolation techniques, we give perturbative capacities
estimates for a wider class of quantum channels by comparison to TRO channels.
Our estimates applies mainly for quantum and private capacity and also strong
converse rates. The examples includes random unitary from group representations
which in general are non-degradable channels.


title: Distinguishing quantum states using Clifford orbits

abstract:
  It is a fundamental property of quantum mechanics that information is lost as
a result of performing measurements. Indeed, with every quantum measurement one
can associate a number -- its POVM norm constant -- that quantifies how much
the distinguishability of quantum states degrades in the worst case as a result
of the measurement. This raises the obvious question which measurements
preserve the most information in these sense of having the largest norm
constant. While a number of near-optimal schemes have been found (e.g. the
uniform POVM, or complex projective 4-designs), they all seem to be difficult
to implement in practice. Here, we analyze the distinguishability of quantum
states under measurements that are orbits of the Clifford group. The Clifford
group plays an important role e.g. in quantum error correction, and its
elements are considered simple to implement. We find that the POVM norm
constants of Clifford orbits depend on the effective rank of the states that
should be distinguished, as well as on a quantitative measure of the "degree of
localization in phase space" of the vectors in the orbit. The most important
Clifford orbit is formed by the set of stabilizer states. Our main result
implies that stabilizer measurements are essentially optimal for distinguishing
pure quantum states. As an auxiliary result, we use the methods developed here
to prove new entropic uncertainty relations for stabilizer measurements. This
paper is based on a very recent analysis of the representation theory of tensor
powers of the Clifford group.


title: $h^\ast$-polynomials of zonotopes

abstract:
  The Ehrhart polynomial of a lattice polytope $P$ encodes information about
the number of integer lattice points in positive integral dilates of $P$. The
$h^\ast$-polynomial of $P$ is the numerator polynomial of the generating
function of its Ehrhart polynomial. A zonotope is any projection of a higher
dimensional cube. We give a combinatorial description of the
$h^\ast$-polynomial of a lattice zonotope in terms of refined descent
statistics of permutations and prove that the $h^\ast$-polynomial of every
lattice zonotope has only real roots and therefore unimodal coefficients.
Furthermore, we present a closed formula for the $h^\ast$-polynomial of a
zonotope in matroidal terms which is analogous to a result by Stanley (1991) on
the Ehrhart polynomial. Our results hold not only for $h^\ast$-polynomials but
carry over to general combinatorial positive valuations. Moreover, we give a
complete description of the convex hull of all $h^\ast$-polynomials of
zonotopes in a given dimension: it is a simplicial cone spanned by refined
Eulerian polynomials.


title: Quantitative estimate on singularities in isoperimetric clusters

abstract:
  We prove a quantitative estimate on the number of certain singularities in
almost minimizing clusters. In particular, we consider the singular points
belonging to the lowest stratum of the Federer-Almgren stratification (namely,
where each tangent cone does not split a $\R$) with maximal density. As a
consequence we obtain an estimate on the number of triple junctions in
$2$-dimensional clusters and on the number of tetrahedral points in $3$
dimensions, that in turn implies that the boundaries of volume-constrained
minimizing clusters form at most a finite number of equivalence classes modulo
homeomorphism of the boundary, provided that the prescribed volumes vary in a
compact set. The method is quite general and applies also to other problems:
for instance, to count the number of singularities in a codimension 1
area-minimizing surface in $\R^8$.


title:
Properties of the First-order Fermi acceleration in fast magnetic
  reconnection driven by turbulence in collisional MHD flows

abstract:
  Fast magnetic reconnection may occur in different astrophysical sources,
producing flare-like emission and particle acceleration. Currently, this
process is being studied as an efficient mechanism to accelerate particles via
a first-order Fermi process. In this work we analyse the acceleration rate and
the energy distribution of test particles injected in three-dimensional
magnetohydrodynamical (MHD) domains with large-scale current sheets where
reconnection is made fast by the presence of turbulence. We study the
dependence of the particle acceleration time with the relevant parameters of
the embedded turbulence, i.e., the Alfv\'en speed $V_{\rm A}$, the injection
power $P_{\rm inj}$ and scale $k_{\rm inj}$ ($k_{\rm inj} = 1/l_{\rm inj}$). We
find that the acceleration time follows a power-law dependence with the
particle kinetic energy: $t_{acc} \propto E^{\alpha}$, with $0.2 < \alpha <
0.6$ for a vast range of values of $c / V_{\rm A} \sim 20 - 1000$. The
acceleration time decreases with the Alfv\'en speed (and therefore with the
reconnection velocity) as expected, having an approximate dependence $t_{acc}
\propto (V_{\rm A} / c)^{-\kappa}$, with $\kappa \sim 2.1- 2.4$ for particles
reaching kinetic energies between $1 - 100 \, m_p c^2$, respectively.
Furthermore, we find that the acceleration time is only weakly dependent on the
$P_{\rm inj}$ and $l_{\rm inj}$ parameters of the turbulence. The particle
spectrum develops a high-energy tail which can be fitted by a hard power-law
already in the early times of the acceleration, in consistency with the results
of kinetic studies of particle acceleration by magnetic reconnection in
collisionless plasmas.


title: f-Biharmonic and bi-f-harmonic submanifolds of generalized space forms

abstract:
  We study f-biharmonic and bi-f-harmonic submanifolds in both generalized
complex and Sasakian space forms. We prove necessary and sufficient condition
for f-biharmonicity and bi-f-harmonicity in the general case and many
particular cases. Some non-existence results are also obtained.


title: The range and valence of a real Smirnov function

abstract:
  We give a complete description of the possible ranges of real Smirnov
functions (quotients of two bounded analytic functions on the open unit disk
where the denominator is outer and such that the radial boundary values are
real almost everywhere on the unit circle). Our techniques use the theory of
unbounded symmetric Toeplitz operators, some general theory of unbounded
symmetric operators, classical Hardy spaces, and an application of the
uniformization theorem. In addition, we completely characterize the possible
valences for these real Smirnov functions when the valence is finite. To do so
we construct Riemann surfaces we call disk trees by welding together copies of
the unit disk and its complement in the Riemann sphere. We also make use of
certain trees we call valence trees that mirror the structure of disk trees.


title: On normality of f.pk-structures on g-manifolds

abstract:
  We consider higher dimensional generalisations of normal almost contact
structures, the so called f.pk-structures where parallelism spans a Lie algebra
g (f.pk-g-structures). Two types of these structures are discussed. In the
first case, we construct an almost complex structure on a product manifold
mirroring K-structures. We show that the natural normality condition can be
satisfied only when g is abelian. The second case we consider is when the Lie
algebra in question is 3-dimensional, but the almost complex structure on a
product is constructed in a different manner. In both cases the normality
conditions are expressed in terms of the structure tensors.


title: On the number of factorizations of an integer

abstract:
  Let $f(n)$ denote the number of unordered factorizations of a positive
integer $n$ into factors larger than $1$. We show that the number of distinct
values of $f(n)$, less than or equal to $x$, is at most $\exp \left( C
\sqrt{\frac{\log x}{\log \log x}} \left( 1 + o(1) \right) \right)$, where
$C=2\pi\sqrt{2/3}$ and $x$ is sufficiently large. This improves upon a previous
result of the first author and F. Luca.


title:
A short proof of Minkowski's second theorem and its application to some
  open questions

abstract:
  In this paper we present a surprisingly short proof of Minkowski's second
theorem. The author hopes there is no mistake in it, though the argument seems
to be too plain to contain one. Also, we apply the main construction of the
proof to some problems concerning the anomaly of a convex body, the density of
the densest lattice packing, lattice point enumerator, and Ehrhart polynomial.


title:
Gyromagnetic factor of rotating disks of electrically charged dust in
  general relativity

abstract:
  We calculated the dimensionless gyromagnetic ratio ("$g$-factor") of
self-gravitating, uniformly rotating disks of dust with a constant specific
charge $\epsilon$. These disk solutions to the Einstein-Maxwell equations
depend on $\epsilon$ and a "relativity parameter" $\gamma$ ($0<\gamma\le 1$) up
to a scaling parameter. Accordingly, the $g$-factor is a function
$g=g(\gamma,\epsilon)$. The Newtonian limit is characterized by $\gamma \ll 1$,
whereas $\gamma\to 1$ leads to a black-hole limit. The $g$-factor, for all
$\epsilon$, approaches the values $g=1$ as $\gamma\to 0$ and $g=2$ as
$\gamma\to 1$.


title:
Effects of binary stellar populations on direct collapse black hole
  formation

abstract:
  The critical Lyman--Werner flux required for direct collapse blackholes
(DCBH) formation, or J$_{crit}$, depends on the shape of the irradiating
spectral energy distribution (SED). The SEDs employed thus far have been
representative of {{realistic}} single stellar populations. We study the effect
of binary stellar populations on the formation of DCBH, as a result of their
contribution to the Lyman--Werner radiation field. Although binary populations
with ages $>$ 10 Myr yield a larger LW photon output, we find that the
corresponding values of J$_{crit}$ can be up to 100 times higher than single
stellar populations. We attribute this to the shape of the binary SEDs as they
produce a sub--critical rate of H$^-$ photodetaching 0.76 eV photons as
compared to single stellar populations, reaffirming the role that H$^-$ plays
in DCBH formation. This further corroborates the idea that DCBH formation is
better understood in terms of a critical region in the H$_2$--H$^-$
photo--destruction rate parameter space, rather than a single value of LW flux.


title: The blazar sequence 2.0

abstract:
  I discuss the spectral energy distribution (SED) of all blazars with redshift
detected by the {\it Fermi} satellite and listed in the 3LAC catalog. I will
update the so called "blazar sequence" from the phenomenological point of view,
with no theory or modelling. I will show that: i) pure data show that jet and
accretion power are related; ii) the updated blazar sequence maintains the
properties of the old version, albeit with a less pronounced dominance of the
$\gamma$--ray emission; iii) at low bolometric luminosities, two different type
of objects have the same high energy power: low black hole mass flat spectrum
radio quasars and high mass BL Lacs. Therefore, at low luminosities, there is a
very large dispersion of SED shapes; iv) in low power BL Lacs, the contribution
of the host galaxy is important. Remarkably, the luminosity distribution of the
host galaxies of BL Lacs are spread in a very narrow range; v) a simple sum of
two smoothly joining power laws can describe the blazar SEDs very well.


title:
Inequalities for Quadratic Operator Perspective of Convex Functions and
  Bounded Linear Operators in Hilbert Spaces

abstract:
  In this paper we introduce the concept of quadratic operator perspective for
a continuous function {\Phi} defined on the positive semi-axis of real numbers.
This generalize the quadratic weighted operator geometric mean and the
quadratic relative operator entropy. Some inequalities for this perspective of
convex functions are established. Applications for quadratic weighted operator
geometric mean and quadratic relative operator entropy are also provided.


title: CP-violating phase on magnetized toroidal orbifolds

abstract:
  We study the CP-violating phase of the quark sector in the $U(8)$ flavor
model on $T^2/Z_N \, (N=2,3,4,6)$ with non-vanishing magnetic fluxes, where
properties of possible origins of the CP violation are investigated minutely.
In this system, a non-vanishing value is mandatory in the real part of the
complex modulus parameter $\tau$ of the two-dimensional torus. On $T^2$ without
orbifolding, underlying discrete flavor symmetries severely restrict the form
of Yukawa couplings and it is very difficult to reproduce the observed pattern
in the quark sector including the CP-violating phase $\delta_{\rm CP}$. In
cases of multiple Higgs doublets emerging on $T^2/Z_2$, the mass matrices of
the zero-mode fermions can be written in the Gaussian textures by choosing
appropriate configurations of vacuum expectation values of the Higgs fields.
When such Gaussian textures of mass matrices are realized, we show that all of
the quark profiles, which are mass hierarchies among the quarks, quark mixing
angles, and $\delta_{\rm CP}$ can be simultaneously realized.


title:
Comprehending particle production at RHIC and LHC energies using global
  measurements

abstract:
  The centrality dependence of the charged-particle multiplicity densities
($dN_{ch}/d\eta$) and transverse energy densities ($dE_{T}/d\eta$) are
investigated using the two-component Glauber approach for broad range of
energies in heavy ion collisions at RHIC and LHC. A comprehensive study shows
that the data is well described within the framework of two component model
which includes the contribution of "soft processes" and "hard processes" for
different centrality classes and energies. The data at two different energies
are compared by means of the ratio of $dN_{ch}/d\eta$ (and $dE_{T}/d\eta$) to
see the interplay of energy and $x$-scaling.


title: Spectral line intensity and polarization in gas-dusty medium

abstract:
  We study the standard spectral line radiative transfer equation for media
consisting of resonant atoms and non-resonant components (the dust grains and
the atoms without considered spectral transition). Our goal is to study the
intensity and polarization of the resonance radiation emerging from
semi-infinite atmosphere. Using the known technique of resolvent matrices, we
obtain the exact solution of vectorial radiative transfer equation for various
sources of non-polarized radiation in semi-infinite atmosphere. Homogeneous,
linear increasing and exponentially decreasing sources are considered. Recall,
that homogeneous sources correspond to the isothermal atmosphere and the
exponential ones correspond to the incident radiation with different angles of
inclination.


title: Expansion under climate change: the genetic consequences

abstract:
  Range expansion and range shifts are crucial population responses to climate
change. Genetic consequences are not well understood but are clearly coupled to
ecological dynamics that, in turn, are driven by shifting climate conditions.
We model a population with a deterministic reaction-- diffusion model coupled
to a heterogeneous environment that develops in time due to climate change. We
decompose the resulting travelling wave solution into neutral genetic
components to analyse the spatio-temporal dynamics of its genetic structure.
Our analysis shows that range expansions and range shifts under slow climate
change preserve genetic diversity. This is because slow climate change creates
range boundaries that promote spatial mixing of genetic components.
Mathematically , the mixing leads to so-called pushed travelling wave
solutions. This mixing phenomenon is not seen in spatially homogeneous
environments, where range expansion reduces genetic diversity through gene
surfing arising from pulled travelling wave solutions. However, the
preservation of diversity is diminished when climate change occurs too quickly.
Using diversity indices, we show that fast expansions and range shifts erode
genetic diversity more than slow range expansions and range shifts. Our study
provides analytical insight into the dynamics of travelling wave solutions in
heterogeneous environments.


title: Representations of $p$-convolution algebras on $L^q$-spaces

abstract:
  For a nontrivial locally compact group $G$, and $p\in [1,\infty)$, consider
the Banach algebras of $p$-pseudofunctions, $p$-pseudomeasures, $p$-convolvers,
and the full group $L^p$-operator algebra. We show that these Banach algebras
are operator algebras if and only if $p=2$. More generally, we show that for
$q\in [1,\infty)$, these Banach algebras can be represented on an $L^q$-space
if and only if one of the following holds: (a) $p=2$ and $G$ is abelian; or (b)
$|\frac 1p - \frac 12|=|\frac 1q - \frac 12|$. This result can be interpreted
as follows: for $p,q\in [1,\infty)$, the $L^p$- and $L^q$-representation
theories of a group are incomparable, except in the trivial cases when they are
equivalent.
  As an application, we show that, for distinct $p,q\in [1,\infty)$, if the
$L^p$ and $L^q$ crossed products of a topological dynamical system are
isomorphic, then $\frac 1p + \frac 1q=1$. In order to prove this, we study the
following relevant aspects of $L^p$-crossed products: existence of approximate
identities, duality with respect to $p$, and existence of canonical isometric
maps from group algebras into their multiplier algebras.


title:
The clustering of galaxies in the SDSS-III Baryon Oscillation
  Spectroscopic Survey: higher-order correlations revealed by germ-grain
  Minkowski Functionals

abstract:
  We probe the higher-order clustering of the galaxies in the final data
release (DR12) of the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic
Survey (BOSS) using the method of germ-grain Minkowski Functionals (MFs). Our
sample consists of 410,615 BOSS galaxies from the northern Galactic cap in the
redshift range 0.450--0.595. We show the MFs to be sensitive to contributions
up to the six-point correlation function for this data set. We ensure with a
custom angular mask that the results are more independent of boundary effects
than in previous analyses of this type. We extract the higher-order part of the
MFs and quantify the difference to the case without higher-order correlations.
The resulting $\chi^{2}$ value of over 10,000 for a modest number of degrees of
freedom, O(200), indicates a 100-sigma deviation and demonstrates that we have
a highly significant signal of the non-Gaussian contributions to the galaxy
distribution. This statistical power can be useful in testing models with
differing higher-order correlations. Comparing the galaxy data to the QPM and
MultiDark-Patchy mocks, we find that the latter better describes the observed
structure. From an order-by-order decomposition we expect that, for example,
already a reduction of the amplitude of the MD-Patchy mock power spectrum by 5%
would remove the remaining tension.


title: Shaping of the inner Oort cloud by Planet Nine

abstract:
  We present a numerical simulation of the dynamical interaction between the
proposed Planet Nine and a debris disk around the Sun for $4{\rm Gyr}$,
accounting for the secular perturbation of the four giant planets in two
scenarios: (a) an initially thin circular disk around the Sun (b) inclined and
eccentric disk. We show, in both scenarios, that Planet Nine governs the
dynamics in between $1000{\rm -5000{\rm AU}}$ and forms spherical structure in
the inner part ($\sim1000{\rm AU}$) and inclined disk. This structure is the
outcome of mean motion resonances and secular interaction with Planet Nine. We
compare the morphology of this structure with the outcome from a fly-by
encounter of a star with the debris disk and show distinct differences between
the two cases. We predict that this structure serves as a source of comets and
calculate the resulting comet production rate to be detectable.


title:
The Infrared-Gamma-Ray Connection: A WISE View of the Extragalactic
  Gamma-Ray Sky

abstract:
  Using data from the WISE all-sky survey we discovered that the non-thermal
infrared (IR) emission of blazars, the largest known population of
extragalactic gamma-ray sources, has peculiar spectral properties. In this
work, we confirm and strengthen our previous analyses using the latest
available releases of both the WISE and the Fermi source catalogs. We also show
that there is a tight correlation between the mid-IR colors and the gamma-ray
spectral index of Fermi blazars. We name this correlation "the
infrared--gamma-ray connection". We discuss how this connection links both the
emitted powers and the spectral shapes of particles accelerated in jets arising
from blazars over ten decades in energy. Based on this evidence, we argue that
the infrared--gamma-ray connection is stronger than the well known
radio--gamma-ray connection.


title: Composite fermion duality for half-filled multicomponent Landau Levels

abstract:
  We study the interplay of particle-hole symmetry and fermion-vortex duality
in multicomponent half-filled Landau levels, such as quantum Hall gallium
arsenide bilayers and graphene. For the $\nu{=}1/2{+}1/2$ bilayer, we show that
particle-hole-symmetric interlayer Cooper pairing of composite fermions leads
to precisely the same phase as the electron exciton condensate realized in
experiments. This equivalence is easily understood by applying the recent Dirac
fermion formulation of $\nu{=}1/2$ to two components. It can also be described
by Halperin-Lee-Read composite fermions undergoing interlayer $p_x{+}ip_y$
pairing. An RG analysis showing strong instability to interlayer pairing at
large separation $d\rightarrow \infty$ demonstrates that two
initially-decoupled composite Fermi liquids can be smoothly tuned into the
conventional bilayer exciton condensate without encountering a phase
transition. We also discuss multicomponent systems relevant to graphene, derive
related phases including a $Z_2$ gauge theory with spin-half visons, and argue
for symmetry-enforced gaplessness under full SU$(N_f)$ flavor symmetry when the
number of components $N_f$ is even.


title: Theory of quantum kagome ice and vison zero modes

abstract:
  We derive an effective $Z_2$ gauge theory to describe the quantum kagome ice
(QKI) state that has been observed by Carrasquilla $\textit{et. al.}$ in Monte
Carlo studies of the $S = 1/2$ kagome XYZ model in a Zeeman field. The
numerical results on QKI are consistent with, but do not confirm or rule out,
the hypothesis that it is a $Z_2$ spin liquid. Our effective theory allows us
to explore this hypothesis and make a striking prediction for future numerical
studies, namely that symmetry-protected vison zero modes arise at lattice
disclination defects, leading to a Curie defect term in the spin
susceptibility, and a characteristic $(N_{dis} - 1) \ln 2$ contribution to the
entropy, where $N_{dis}$ is the number of disclinations. Only the $Z_2$ Ising
symmetry is required to protect the vison zero modes. This is remarkable
because a unitary $Z_2$ symmetry cannot be responsible for symmetry-protected
degeneracies of local degrees of freedom. We also discuss other signatures of
symmetry fractionalization in the $Z_2$ spin liquid, and phase transitions out
of the $Z_2$ spin liquid to nearby ordered phases.


title: Realizing topological surface states in a lower-dimensional flat band

abstract:
  The anomalous surface states of symmetry protected topological (SPT) phases
are usually thought to be only possible in conjunction with the higher
dimensional topological bulk. However, it has recently been realized that a
class of anomalous SPT surface states can be realized in the same dimension if
symmetries are allowed to act in a nonlocal fashion. An example is the
particle-hole symmetric half filled Landau level, which effectively realizes
the anomalous surface state of a 3D chiral Topological Insulator (class AIII).
A dual description in terms of Dirac composite fermions has also been
discussed. Here we explore generalizations of these constructions to
multicomponent quantum Hall states. Our results include a duality mapping of
the bilayer case to composite bosons with Kramers degeneracy and the
possibility of a particle hole symmetric integer quantum Hall state when the
number of components is a multiple of eight. Next, we make a further extension
by half filling other classes of topological bands and imposing particle hole
symmetry. When applied to time-reversal invariant topological insulators we
realize a different chiral class (CII) topological surface state. Notably,
half-filling a 3D TI band allows for the realization of the surface of the
otherwise inaccessible 4D topological insulator, which supports an anomalous 3D
Dirac cone. Surface topological orders equivalent to the 3D Dirac cone (from
the global anomaly standpoint) are constructed and connections to Witten's
SU(2) anomaly are made. These observations may also be useful for numerical
simulations of topological surface states and of Dirac fermions without fermion
doubling.


title: Superfluid helium II as the QCD vacuum

abstract:
  We study the winding number susceptibility < I^2> in a superfluid system and
the topological susceptibility < Q^2> in QCD. We argue that both correlation
functions exhibit similar structures, including the generation of the contact
terms. We discuss the nature of the contact term in superfluid system and argue
that it has exactly the same origin as in QCD, and it is related to the long
distance physics which cannot be associated with conventional microscopical
degrees of freedom such as phonons and rotons. We emphasize that the conceptual
similarities between superfluid system and QCD may lead, hopefully, to a deeper
understanding of the topological features of a superfluid system as well as the
QCD vacuum.

categories: cond-mat.stat-mech hep-lat hep-ph hep-th


title: Quantum critical properties of a metallic spin density wave transition

abstract:
  We report on numerically exact determinantal quantum Monte Carlo simulations
of the onset of spin-density wave (SDW) order in itinerant electron systems
captured by a sign-problem-free two-dimensional lattice model. Extensive
measurements of the SDW correlations in the vicinity of the phase transition
reveal that the critical dynamics of the bosonic order parameter are well
described by a dynamical critical exponent z = 2, consistent with Hertz-Millis
theory, but are found to follow a finite-temperature dependence that does not
fit the predicted behavior of the same theory. The presence of critical SDW
fluctuations is found to have a strong impact on the fermionic quasiparticles,
giving rise to a dome-shaped superconducting phase near the quantum critical
point. In the superconducting state we find a gap function that has an opposite
sign between the two bands of the model and is nearly constant along the Fermi
surface of each band. Above the superconducting $T_c$ our numerical simulations
reveal a nearly temperature and frequency independent self energy causing a
strong suppression of the low-energy quasiparticle spectral weight in the
vicinity of the hot spots on the Fermi surface. This indicates a clear
breakdown of Fermi liquid theory around these points.


title:
PKDGRAV3: Beyond Trillion Particle Cosmological Simulations for the Next
  Era of Galaxy Surveys

abstract:
  We report on the successful completion of a 2 trillion particle cosmological
simulation to z=0 run on the Piz Daint supercomputer (CSCS, Switzerland), using
4000+ GPU nodes for a little less than 80h of wall-clock time or 350,000 node
hours. Using multiple benchmarks and performance measurements on the US Oak
Ridge National Laboratory Titan supercomputer, we demonstrate that our code
PKDGRAV3, delivers, to our knowledge, the fastest time-to-solution for
large-scale cosmological N-body simulations. This was made possible by using
the Fast Multipole Method in conjunction with individual and adaptive particle
time steps, both deployed efficiently (and for the first time) on
supercomputers with GPU-accelerated nodes. The very low memory footprint of
PKDGRAV3 allowed us to run the first ever benchmark with 8 trillion particles
on Titan, and to achieve perfect scaling up to 18000 nodes and a peak
performance of 10 Pflops.


title: The dust content of galaxies from z = 0 to z = 9

abstract:
  We study the dust content of galaxies from $z=0$ to $z=9$ in semi-analytic
models of galaxy formation that include new recipes to track the production and
destruction of dust. We include condensation of dust in stellar ejecta, the
growth of dust in the interstellar medium (ISM), the destruction of dust by
supernovae and in the hot halo, and dusty winds and inflows. The rate of dust
growth in the ISM depends on the metallicity and density of molecular clouds.
Our fiducial model reproduces the relation between dust mass and stellar mass
from $z=0$ to $z=7$, the number density of galaxies with dust masses less than
$10^{8.3}\,\rm{M}_\odot$, and the cosmic density of dust at $z=0$. The model
accounts for the double power-law trend between dust-to-gas (DTG) ratio and
gas-phase metallicity of local galaxies and the relation between DTG ratio and
stellar mass. The dominant mode of dust formation is dust growth in the ISM,
except for galaxies with $M_*<10^7\,\rm{M}_\odot$, where condensation of dust
in supernova ejecta dominates. The dust-to-metal ratio of galaxies depends on
the gas-phase metallicity, unlike what is typically assumed in cosmological
simulations. Model variants including higher condensation efficiencies, a fixed
timescale for dust growth in the ISM, or no growth at all reproduce some of the
observed constraints, but fail to simultaneously reproduce the shape of dust
scaling relations and the dust mass of high-redshift galaxies.


title:
A framework for testing leptonic unitarity by neutrino oscillation
  experiments

abstract:
  If leptonic unitarity is violated by new physics at an energy scale much
lower than the electroweak scale, which we call low-scale unitarity violation,
it has different characteristic features from those expected in unitarity
violation at high-energy scales. They include maintaining flavor universality
and absence of zero-distance flavor transition. We present a framework for
testing such unitarity violation at low energies by neutrino oscillation
experiments. Starting from the unitary 3 active plus $N$ (arbitrary integer)
sterile neutrino model we show that by restricting the active-sterile and
sterile-sterile neutrino mass squared differences to $\gtrsim$ 0.1 eV$^2$ the
oscillation probability in the $(3+N)$ model becomes insensitive to details of
the sterile sector, providing a nearly model-independent framework for testing
low-scale unitarity violation. Yet, the presence of the sterile sector leaves
trace as a constant probability leaking term, which distinguishes low-scale
unitarity violation from the high-scale one. The non-unitary mixing matrix in
the active neutrino subspace is common for the both cases. We analyze how
severely the unitarity violation can be constrained in $\nu_{e}$-row by taking
a JUNO-like setting to simulate medium baseline reactor experiments. Possible
modification of the features of the $(3+N)$ model due to matter effect is
discussed to first order in the matter potential.