title:
Stabilized Sparse Scaling Algorithms for Entropy Regularized Transport
  Problems

abstract:
  Scaling algorithms for entropic transport-type problems have become a very
popular numerical method, encompassing Wasserstein barycenters, multi-marginal
problems, gradient flows and unbalanced transport. However, a standard
implementation of the scaling algorithm has several numerical limitations: the
scaling factors diverge and convergence becomes impractically slow as the
entropy regularization approaches zero. Moreover, handling the dense kernel
matrix becomes unfeasible for large problems. To address this, we combine
several modifications: A log-domain stabilized formulation, the well-known
epsilon-scaling heuristic, an adaptive truncation of the kernel and a
coarse-to-fine scheme. This permits the solution of larger problems with
smaller regularization and negligible truncation error. A new convergence
analysis of the Sinkhorn algorithm is developed, working towards a better
understanding of epsilon-scaling. Numerical examples illustrate efficiency and
versatility of the modified algorithm.


title:
High-frequency asymptotics of the vertex function: diagrammatic
  parametrization and algorithmic implementation

abstract:
  Vertex functions are a crucial ingredient of several forefront many-body
algorithms in condensed matter physics. However, the full treatment of their
frequency and momentum dependence severely restricts numerical calculations. A
significant advancement requires an efficient treatment of the high-frequency
asymptotic behavior of the vertex functions. In this work, we first provide a
detailed diagrammatic analysis of the high-frequency structures and their
physical interpretation. Based on these insights, we propose a parametrization
scheme, which captures the whole high-frequency domain for arbitrary values of
the Coulomb interaction and electronic density, and we discuss the details of
its algorithmic implementation in many-body solvers based on parquet-equations
as well as functional renormalization group schemes. Finally, we assess its
validity by comparing our results for a single impurity Anderson model with
exact diagonalization calculations. The proposed parametrization is pivotal for
the algorithmic development of all quantum many-body methods based on vertex
functions arising from both local and non-local static microscopic interactions
as well as effective dynamic interactions which uniformly approach a static
value for large frequencies. In this way, our present technique can
substantially improve vertex-based diagrammatic approaches including spatial
correlations beyond dynamical mean-field theory.


title: Induced Tur\'an numbers

abstract:
  The classical K\H{o}v\'ari-S\'os-Tur\'an theorem states that if $G$ is an
$n$-vertex graph with no copy of $K_{s,t}$ as a subgraph, then the number of
edges in $G$ is at most $O(n^{2-1/s})$. We prove that if one forbids $K_{s,t}$
as an induced/ subgraph, and also forbids any/ fixed graph $H$ as a (not
necessarily induced) subgraph, the same asymptotic upper bound still holds,
with different constant factors. This introduces a nontrivial angle from which
to generalize Tur\'an theory to induced forbidden subgraphs, which this paper
explores. Along the way, we derive a nontrivial upper bound on the number of
cliques of fixed order in a $K_r$-free graph with no induced copy of $K_{s,t}$.
This result is an induced analog of a recent theorem of Alon and Shikhelman and
is of independent interest.


title:
The canonical Luminous Blue Variable AG Car and its neighbor Hen 3-519
  are much closer than previously assumed

abstract:
  The strong mass loss of Luminous Blue Variables (LBVs) is thought to play a
critical role in massive-star evolution, but their place in the evolutionary
sequence remains debated. A key to understanding their peculiar instability is
their high observed luminosities, which often depends on uncertain distances.
Here we report direct distances and space motions of four canonical Milky Way
LBVs---AG~Car, HR~Car, HD~168607, and (candidate) Hen~3-519---from the Gaia
first data release. Whereas the distances of HR~Car and HD~168607 are
consistent with previous literature estimates within the considerable
uncertainties, Hen~3-519 and AG~Car, both at $\sim$2~kpc, are much closer than
the 6--8~kpc distances previously assumed. As a result, Hen~3-519 moves far
from the locus of LBVs on the HR Diagram, making it a much less luminous
object. For AG~Car, considered a defining example of a classical LBV, its lower
luminosity would also move it off the S~Dor instability strip. Lower
luminosities allow both AG~Car and Hen~3-519 to have passed through a previous
red supergiant phase, lower the mass estimates for their shell nebulae, and
imply that binary evolution is needed to account for their peculiarities. These
results may also impact our understanding of LBVs as potential supernova
progenitors and their isolated environments. Improved distances will be
provided in the Gaia second data release, which will include additional LBVs.
AG~Car and Hen~3-519 hint that this new information may alter our traditional
view of LBVs.


title:
Scattering for the radial 3D cubic focusing inhomogeneous nonlinear
  Schr\"odinger equation

abstract:
  The purpose of this work is to study the 3D focusing inhomogeneous nonlinear
Schr\"odinger equation $$ i u_t +\Delta u+|x|^{-b}|u|^2 u = 0, $$ where
$0<b<1/2$. Let $Q$ be the ground state solution of $-Q+\Delta Q+
|x|^{-b}|Q|^{2}Q=0$ and $s_c=(1+b)/2$. We show that if the radial initial data
$u_0$ belongs to $H^1(\mathbb{R}^3)$ and satisfies
$E(u_0)^{s_c}M(u_0)^{1-s_c}<E(Q)^{s_c}M(Q)^{1-s_c}$ and $\| \nabla u_0
\|_{L^2}^{s_c} \|u_0\|_{L^2}^{1-s_c}<\|\nabla Q \|_{L^2}^{s_c}
\|Q\|_{L^2}^{1-s_c}$, then the corresponding solution is global and scatters in
$H^1(\mathbb{R}^3)$. Our proof is based in the ideas introduced by Kenig-Merle
\cite{KENIG} in their study of the energy-critical NLS and Holmer-Roudenko
\cite{HOLROU} for the radial 3D cubic NLS.


title: Initial Ideals of Pfaffian Ideals

abstract:
  We resolve a conjecture about a class of binomial initial ideals of
$I_{2,n}$, the ideal of the Grassmannian, Gr$(2,\mathbb{C}^n$), which are
associated to phylogenetic trees. For a weight vector $\omega$ in the tropical
Grassmannian, $in_\omega(I_{2,n}) = J_\mathcal{T}$ is the ideal associated to
the tree $\mathcal{T}$. The ideal generated by the $2r \times 2r$ subpfaffians
of a generic $n \times n$ skew-symmetric matrix is precisely
$I_{2,n}^{\{r-1\}}$, the $(r-1)$-secant of $I_{2,n}$. We prove necessary and
sufficient conditions on the topology of $\mathcal{T}$ in order for
$in_\omega(I_{2,n})^{\{2\}} = J_\mathcal{T}^{\{2\}}$. We also give a new
classof prime initial ideals of the Pfaffian ideals.


title: ChoiceRank: Identifying Preferences from Node Traffic in Networks

abstract:
  Understanding how users navigate in a network is of high interest in many
applications. We consider a setting where only aggregate node-level traffic is
observed and tackle the task of learning edge transition probabilities. We cast
it as a preference learning problem, and we study a model where choices follow
Luce's axiom. In this case, the $O(n)$ marginal counts of node visits are a
sufficient statistic for the $O(n^2)$ transition probabilities. We show how to
make the inference problem well-posed regardless of the network's structure,
and we present ChoiceRank, an iterative algorithm that scales to networks that
contains billions of nodes and edges. We apply the model to two clickstream
datasets and show that it successfully recovers the transition probabilities
using only the network structure and marginal (node-level) traffic data.
Finally, we also consider an application to mobility networks and apply the
model to one year of rides on New York City's bicycle-sharing system.


title: The structure of DGA resolutions of monomial ideals

abstract:
  Let $I \subset k[x_1, \dotsc, x_n]$ be a squarefree monomial ideal a
polynomial ring. In this paper we study multiplications on the minimal free
resolution $\mathbb{F}$ of $k[x_1, \dotsc, x_n]/I$. In particular, we
characterize the possible vectors of total Betti numbers for such ideals which
admit a differential graded algebra (DGA) structure on $\mathbb{F}$. We also
show that under these assumptions the maximal shifts of the graded Betti
numbers are subadditive.
  On the other hand, we present an example of a strongly generic monomial ideal
which does not admit a DGA structure on its minimal free resolution. In
particular, this demonstrates that the Hull resolution and the Lyubeznik
resolution do not admit DGA structures in general.
  Finally, we show that it is enough to modify the last map of $\mathbb{F}$ to
ensure that it admits the structure of a DG algebra.


title: Mixing in Reaction-Diffusion Systems: Large Phase Offsets

abstract:
  We consider Reaction-Diffusion systems on $\mathbb{R}$, and prove diffusive
mixing of asymptotic states $u_0(kx - \phi_{\pm}, k)$, where $u_0$ is a
periodic wave. Our analysis is the first to treat arbitrarily large
phase-offsets $\phi_d = \phi_{+}- \phi_{-}$, so long as this offset proceeds in
a sufficiently regular manner. The offset $\phi_d$ completely determines the
size of the asymptotic profiles, placing our analysis in the large data
setting. In addition, the present result is a global stability result, in the
sense that the class of initial data considered are not near the asymptotic
profile in any sense. We prove global existence, decay, and asymptotic
self-similarity of the associated wavenumber equation. We develop a functional
framework to handle the linearized operator around large Burgers profiles via
the exact integrability of the underlying Burgers flow. This framework enables
us to prove a crucial, new mean-zero coercivity estimate, which we then combine
with a nonlinear energy method.


title:
Universal hydrodynamic mechanisms for crystallization in active
  colloidal suspensions

abstract:
  The lack of detailed balance in active colloidal suspensions allows
dissipation to determine stationary states. Here we show that slow viscous flow
produced by polar or apolar active colloids near plane walls mediates
attractive hydrodynamic forces that drive crystallization. Hydrodynamically
mediated torques tend to destabilize the crystal but stability can be regained
through critical amounts of bottom-heaviness or chiral activity. Numerical
simulations show that crystallization is not nucleational, as in equilibrium,
but is preceded by a spinodal-like instability. Harmonic excitations of the
active crystal relax diffusively but the normal modes are distinct from an
equilibrium colloidal crystal. The hydrodynamic mechanisms presented here are
universal and rationalize recent experiments on the crystallization of active
colloids.


title: Continuum Kinetic and Multi-Fluid Simulations of Classical Sheaths

abstract:
  The kinetic study of plasma sheaths is critical, among other things, to
understand the deposition of heat on walls, the effect of sputtering, and
contamination of the plasma with detrimental impurities. The plasma sheath also
provides a boundary condition and can often have a significant global impact on
the bulk plasma. In this paper, kinetic studies of classical sheaths are
performed with the continuum code, Gkeyll, that directly solves the
Vlasov-Poisson/Maxwell equations. The code uses a novel version of the
finite-element discontinuous Galerkin (DG) scheme that conserves energy in the
continuous-time limit. The electrostatic field is computed using the Poisson
equation. Ionization and scattering collisions are included, however, surface
effects are neglected. The aim of this work is to introduce the
continuum-kinetic method and compare its results to those obtained from an
already established finite-volume multi-fluid model also implemented in Gkeyll.
Novel boundary conditions on the fluids allow the sheath to form without
specifying wall fluxes, so the fluids and fields adjust self-consistently at
the wall. The work presented here demonstrates that the kinetic and fluid
results are in agreement for the momentum flux, showing that in certain
regimes, a multi-fluid model can be a useful approximation for simulating the
plasma boundary. There are differences in the electrostatic potential between
the fluid and kinetic results. Further, the direct solutions of the
distribution function presented here highlight the non-Maxwellian distribution
of electrons in the sheath, emphasizing the need for a kinetic model.


title: The intrinsic geometry on bounded pseudoconvex domains

abstract:
  The Diederich--Forn\ae ss index has been introduced since 1977 to classify
bounded pseudoconvex domains. In this article, we derive several intrinsic,
geometric conditions on boundary of domains for arbitrary indexes. Many
results, in the past, by various mathematicians estimated the index by assuming
some properties of domains. Our motivation of this paper is, the other way
around, to look for how the index effects properties and shapes of domains.
Especially, we look for a necessary condition of all bounded pseudoconvex
domains $\Omega\subset\mathbb{C}^2$ with the Diederich--Forn\ae ss index 1. We
also show that, when the Levi-flat set of $\partial\Omega$ is a closed Riemann
surface, then the necessary condition can be simplified.


title: Moment Representations of Exceptional $X_1$ Orthogonal Polynomials

abstract:
  We obtain representations of $X_1$ exceptional orthogonal polynomials through
determinants of matrices that have certain adjusted moments as entries. We
start out directly from the Darboux transformation, allowing for a universal
perspective, rather than dependent upon the particular system (Jacobi or Type
of Laguerre polynomials). We include a recursion formula for the adjusted
moments and provide the initial adjusted moments for each system.
  Throughout we relate to the various examples of $X_1$ exceptional orthogonal
polynomials. We especially focus on and provide complete proofs for the Jacobi
and the Type III Laguerre case, as they are less prevalent in literature.
  Lastly, we include a preliminary discussion explaining that the higher
co-dimension setting becomes more involved. The number of possibilities and
choices is exemplified, but only starts, with the lack of a canonical flag.


title: Uncertainty Principle in Loop Quantum Cosmology by Moyal Formalism

abstract:
  In this paper we derive the uncertainty principle for the Loop Quantum
Cosmology homogeneous and isotropic FLWR model with the holonomy-flux algebra.
The uncertainty principle is between the variables $c$, with the meaning of
connection and $\mu$ having the meaning of the physical cell volume to the
power $2/3$, i.e $v^{2/3}$ or a plaquette area. Since both $\mu$ and $c$ are
not operators, but rather the random variables, the Robertson uncertainty
principle derivation that works for hermitian operators, can not be used.
Instead we use the Wigner-Moyal-Groenewold phase space formalism. The
Wigner-Moyal-Groenewold formalism was originally applied to the Heisenberg
algebra of the Quantum Mechanics. One can derive from it both the canonical and
path integral QM as well as the uncertainty principle. In this paper we apply
it to the holonomy-flux algebra in case of the homogeneous and isotropic space.
Another result is the expression for the Wigner function on the space of the
cylindrical wave functions defined on $R_b$ in $c$ variables rather than in
dual space $\mu$ variables.


title:
Generation and Evolution of High-Mach Number, Laser-Driven Magnetized
  Collisionless Shocks in the Laboratory

abstract:
  Shocks act to convert incoming supersonic flows to heat, and in collisionless
plasmas the shock layer forms on kinetic plasma scales through collective
electromagnetic effects. These collisionless shocks have been observed in many
space and astrophysical systems [Smith 1975, Smith 1980, Burlaga 2008, Sulaiman
2015], and are believed to accelerate particles, including cosmic rays, to
extremely high energies [Kazanas 1986, Loeb 2000, Bamba 2003, Masters 2013,
Ackermann 2013]. Of particular importance are the class of high-Mach number,
supercritical shocks [Balogh 2013] ($M_A\gtrsim4$), which must reflect
significant numbers of particles back into the upstream to accommodate entropy
production, and in doing so seed proposed particle acceleration mechanisms
[Blandford 1978, McClements 2001, Caprioli 2014, Matsumoto 2015]. Here we
present the first laboratory generation of high-Mach number magnetized
collisionless shocks created through the interaction of an expanding
laser-driven plasma with a magnetized ambient plasma. Time-resolved,
two-dimensional imaging of plasma density and magnetic fields shows the
formation and evolution of a supercritical shock propagating at magnetosonic
Mach number $M_{ms}\approx12$. Particle-in-cell simulations constrained by
experimental data show in detail the shock formation, separate reflection
dynamics of C$^{+6}$ and H$^{+1}$ ions in the multi-species ambient plasma, and
density and magnetic field compressions and overshoots in the shock layer. The
development of this experimental platform complements present remote sensing
and spacecraft observations, and opens the way for controlled laboratory
investigations of high-Mach number collisionless shocks, including the
mechanisms and efficiency of particle acceleration.


title: Autonomous Racing using Learning Model Predictive Control

abstract:
  A novel learning Model Predictive Control technique is applied to the
autonomous racing problem. The goal of the controller is to minimize the time
to complete a lap. The proposed control strategy uses the data from previous
laps to improve its performance while satisfying safety requirements. Moreover,
a system identification technique is proposed to estimate the vehicle dynamics.
Simulation results with the high fidelity simulator software CarSim show the
effectiveness of the proposed control scheme.


title: Reedy diagrams in V-model categories

abstract:
  We study the category of Reedy diagrams in a $\mm$-model category.
Explicitly, we show that if K is a small category, V is a closed symmetric
monoidal category and C is a closed V-module, then the diagram category V^K is
a closed symmetric monoidal category and the diagram category C^K is a closed
V^K-module. We then prove that if further K is a Reedy category, V is a
monoidal model category and C is a V-model category, then with the Reedy model
category structures, V^K is a monoidal model category and C^K$ is a
$\mm^K-model category provided that either the unit 1 of V is cofibrant or V is
cofibrantly generated.


title:
Observation of an excess at 30 GeV in the opposite sign di-muon spectra
  of ${\rm Z} \to b\overline{ b} + {\rm X}$ events recorded by the ALEPH
  experiment at LEP

abstract:
  The re-analysis of the archived data recorded at the ${\rm Z}^{0}$ resonance
by the ALEPH experiment at LEP during the years 1992-1995 shows an excess in
the opposite sign di-muon mass spectra at 30.40 $\pm$ 0.46 GeV in events
containing b quarks. The excess has a natural width of 1.78 $\pm$ 1.14 GeV.
  The di-muon excess has a local significance around $5\,\sigma$ ($Z_{\rm
asym}$), depending on the background model used. The significances for
background models based on a kernel density approximation stay close to
$3\,\sigma$ ($Z_{\rm freq,\,lee}$), when including a look elsewhere effect.
Another method to obtain a significance value results in at least $2.6\,\sigma$
($Z_{\rm Bi}$). A compatible, but smaller excess is visible in the opposite
di-electron mass spectrum as well.
  This paper uses the data collected by the ALEPH experiment in the years
1992-1995, which have been archived to allow their use for physics analyses
after the closure of the collaboration.


title:
Lax Integrability of the Modified Camassa-Holm Equation and the Concept
  of Peakons

abstract:
  In this Letter we propose that for Lax integrable nonlinear partial
differential equations the natural concept of weak solutions is implied by the
compatibility condition for the respective distributional Lax pairs. We
illustrate our proposal by comparing two concepts of weak solutions of the
modified Camassa-Holm equation pointing out that in the peakon sector (a family
of non-smooth solitons) only one of them, namely the one obtained from the
distributional compatibility condition, supports the time invariance of the
Sobolev $H^1$ norm.


title: A general double-proximal gradient algorithm for d.c. programming

abstract:
  The possibilities of exploiting the special structure of d.c. programs, which
consist of optimizing the difference of convex functions, are currently more or
less limited to variants of the DCA proposed by Pham Dinh Tao and Le Thi Hoai
An in 1997. These assume that either the convex or the concave part, or both,
are evaluated by one of their subgradients.
  In this paper we propose an algorithm which allows the evaluation of both the
concave and the convex part by their proximal points. Additionally, we allow a
smooth part, which is evaluated via its gradient. In the spirit of primal-dual
splitting algorithms, the concave part might be the composition of a concave
function with a linear operator, which are, however, evaluated separately.
  For this algorithm we show that every cluster point is a solution of the
optimization problem. Furthermore, we show the connection to the Toland dual
problem and prove a descent property for the objective function values of a
primal-dual formulation of the problem. Convergence of the iterates is shown if
this objective function satisfies the Kurdyka--\L ojasiewicz property. In the
last part, we apply the algorithm to an image processing model.


title: Linear separation of connected dominating sets in graphs

abstract:
  A connected dominating set in a graph is a dominating set of vertices that
induces a connected subgraph. Following analogous studies in the literature
related to independent sets, dominating sets, and total dominating sets, we
study in this paper the class of graphs in which the connected dominating sets
can be separated from the other vertex subsets by a linear weight function.
More precisely, we say that a graph is connected-domishold if it admits
non-negative real weights associated to its vertices such that a set of
vertices is a connected dominating set if and only if the sum of the
corresponding weights exceeds a certain threshold. We characterize the graphs
in this non-hereditary class in terms of a property of the set of minimal
cutsets of the graph. We give several characterizations for the hereditary
case, that is, when each connected induced subgraph is required to be
connected-domishold. The characterization by forbidden induced subgraphs
implies that the class properly generalizes two well known classes of chordal
graphs, the block graphs and the trivially perfect graphs. Finally, we study
certain algorithmic aspects of connected-domishold graphs. Building on
connections with minimal cutsets and properties of the derived hypergraphs and
Boolean functions, we show that our approach leads to new polynomially solvable
cases of the weighted connected dominating set problem.


title:
Jointly Learning to Align and Convert Graphemes to Phonemes with Neural
  Attention Models

abstract:
  We propose an attention-enabled encoder-decoder model for the problem of
grapheme-to-phoneme conversion. Most previous work has tackled the problem via
joint sequence models that require explicit alignments for training. In
contrast, the attention-enabled encoder-decoder model allows for jointly
learning to align and convert characters to phonemes. We explore different
types of attention models, including global and local attention, and our best
models achieve state-of-the-art results on three standard data sets (CMUDict,
Pronlex, and NetTalk).


title:
The relation of the Dzyaloshinskii-Moriya interaction to spin currents
  and to the spin-orbit field

abstract:
  Starting from the general Berry phase theory of the Dzyaloshinskii-Moriya
interaction (DMI) we derive an expression for the linear contribution of the
spin-orbit interaction (SOI). Thereby, we show analytically that at the first
order in SOI DMI is given by the ground-state spin current. We verify this
finding numerically by ab-initio calculations in Mn/W(001) and Co/Pt(111)
magnetic bilayers. We show that despite the strong SOI from the 5$d$ heavy
metals DMI is well-approximated by the first order in SOI, while the
ground-state spin current is not. We decompose the SOI-linear contribution to
DMI into two parts. One part has a simple interpretation in terms of the Zeeman
interaction between the spin-orbit field and the spin misalignment that
electrons acquire in magnetically noncollinear textures. This interpretation
provides also an intuitive understanding of the symmetry of DMI on the basis of
the spin-orbit field and it explains in a simple way why DMI and ground-state
spin currents are related. Moreover, we show that energy currents driven by
magnetization dynamics and associated to DMI can be explained by
counter-propagating spin currents that carry energy due to their Zeeman
interaction with the spin-orbit field. Finally, we discuss options to modify
DMI by nonequilibrium spin currents excited by electric fields or light.


title:
Lexicons and Minimum Risk Training for Neural Machine Translation:
  NAIST-CMU at WAT2016

abstract:
  This year, the Nara Institute of Science and Technology (NAIST)/Carnegie
Mellon University (CMU) submission to the Japanese-English translation track of
the 2016 Workshop on Asian Translation was based on attentional neural machine
translation (NMT) models. In addition to the standard NMT model, we make a
number of improvements, most notably the use of discrete translation lexicons
to improve probability estimates, and the use of minimum risk training to
optimize the MT system for BLEU score. As a result, our system achieved the
highest translation evaluation scores for the task.


title: Heavy Exotic Molecules

abstract:
  We briefly review the formation of pion-mediated heavy-light exotic molecules
with both charm and bottom, under the general strictures of chiral and heavy
quark symmetries. The charm isosinglet exotic molecules with $J^{PC}=1^{++}$
binds, which we identify as the reported neutral $X(3872)$. The bottom
isotriplet exotic with $J^{PC}=1^{+-}$ binds, and is identified as a mixed
state of the reported charged exotics $Z^+_b(10610)$ and $Z^+_b(10650)$. The
bound bottom isosinglet molecule with $J^{PC}=1^{++}$ is a possible neutral
$X_b(10532)$ to be observed.


title:
Chemisorption of water on the surface of silicon microparticles measured
  by DNP-enhanced NMR

abstract:
  We use dynamic nuclear polarization (DNP) enhanced nuclear magnetic resonance
(NMR) at liquid helium temperatures to directly detect hydrogen attached to the
surface of silicon microparticles. The proton NMR spectrum from a dry sample of
polycrystalline silicon powder (1-5 $\mu$m) shows a distinctively narrow
Lorentzian-shaped resonance with a width of 6.2 kHz, indicative of a very
sparse distribution of protons attached to the silicon surface. These protons
are within a few atomic monolayers of the silicon surface. The high sensitivity
NMR detection of surface protons from low surface area ($0.26 - 1.3 \: m^2/g$)
particles is enabled by an overall signal enhancement of 4150 over the room
temperature NMR signal at the same field. When the particles were suspended in
a solvent with 80% H2O and 20% D2O, the narrow peak was observed to grow in
intensity over time, indicating growth of the sparse surface proton layer.
However, when the particles were suspended in a solvent with 20% H2O and 80%
D2O, the narrow bound-proton peak was observed to shrink due to exchange
between the surface protons and the deuterium in solution. This decrease was
accompanied by a concomitant growth in the intensity of the frozen solvent
peak, as the relative proton concentration of the solvent increased. When the
particles were suspended in the organic solvent hexane, the proton NMR spectra
remained unchanged over time. These results are consistent with the known
chemisorption of water on the silicon surface resulting in the formation of
hydride and hydroxyl species. Low-temperature DNP NMR can thus be used as a
non-destructive probe of surface corrosion for silicon in aqueous environments.
This is important in the context of using silicon MEMS and bioMEMS devices in
such environments, for silicon micro- and nano-particle MRI imaging agents, and
the use of nanosilicon for splitting water in fuel cells.


title: Revisiting Classifier Two-Sample Tests

abstract:
  The goal of two-sample tests is to assess whether two samples, $S_P \sim P^n$
and $S_Q \sim Q^m$, are drawn from the same distribution. Perhaps intriguingly,
one relatively unexplored method to build two-sample tests is the use of binary
classifiers. In particular, construct a dataset by pairing the $n$ examples in
$S_P$ with a positive label, and by pairing the $m$ examples in $S_Q$ with a
negative label. If the null hypothesis "$P = Q$" is true, then the
classification accuracy of a binary classifier on a held-out subset of this
dataset should remain near chance-level. As we will show, such Classifier
Two-Sample Tests (C2ST) learn a suitable representation of the data on the fly,
return test statistics in interpretable units, have a simple null distribution,
and their predictive uncertainty allow to interpret where $P$ and $Q$ differ.
The goal of this paper is to establish the properties, performance, and uses of
C2ST. First, we analyze their main theoretical properties. Second, we compare
their performance against a variety of state-of-the-art alternatives. Third, we
propose their use to evaluate the sample quality of generative models with
intractable likelihoods, such as Generative Adversarial Networks (GANs).
Fourth, we showcase the novel application of GANs together with C2ST for causal
discovery.


title: Hamiltonian Simulation by Qubitization

abstract:
  We present the problem of approximating the time-evolution operator
$e^{-i\hat{H}t}$ to error $\epsilon$, where the Hamiltonian $\hat{H}=(\langle
G|\otimes\hat{\mathcal{I}})\hat{U}(|G\rangle\otimes\hat{\mathcal{I}})$ is the
projection of a unitary oracle $\hat{U}$ onto the state $|G\rangle$ created by
another unitary oracle. Our algorithm solves this with a query complexity
$\mathcal{O}\big(t+\log({1/\epsilon})\big)$ to both oracles that is optimal
with respect to all parameters in both the asymptotic and non-asymptotic
regime, and also with low overhead, using at most two additional ancilla
qubits. This approach to Hamiltonian simulation subsumes important prior art
considering Hamiltonians which are $d$-sparse or a linear combination of
unitaries, leading to significant improvements in space and gate complexity,
such as a quadratic speed-up for precision simulations. It also motivates
useful new instances, such as where $\hat{H}$ is a density matrix. A key
technical result is `qubitization', which uses the controlled version of these
oracles to embed any $\hat{H}$ in an invariant $\text{SU}(2)$ subspace. A large
class of operator functions of $\hat{H}$ can then be computed with optimal
query complexity, of which $e^{-i\hat{H}t}$ is a special case.


title: General Relativity, Time and Determinism

abstract:
  Einstein's theory of general relativity models the physical universe using
spacetimes which satisfy Einstein's gravitational field equations. To date,
Einstein's theory has been enormously successful in modeling observed
gravitational phenomena, both at the astrophysical and the cosmological levels.
  The collection of spacetime solutions of Einstein's equations which have been
effectively used for modeling the physical universe is a very small subset of
the full set of solutions. Among this larger set, there are many spacetimes in
which strange phenomena related to time are present: There are solutions
containing regions in which determinism and the predictability of experimental
outcomes breaks down (the Taub-NUT spacetimes), and there others in which the
breakdown of determinism occurs everywhere (the G\"odel universe).
  Should the existence of these strange solutions lead us to question the
usefulness of Einstein's theory in modeling physical phenomena? Should it
instead lead us to seriously search for strange time phenomena in physics? Or
should we simply treat these solutions as anomalous (if embarrassing)
distractions which we can ignore?
  In this essay, after introducing some basic ideas of special and general
relativity and discussing what it means for a spacetime to be a solution of
Einstein's equations, we explore the use of spacetime solutions for modeling
astrophysical events and cosmology. We then examine some of the spacetime
solutions in which determinism and causal relationships break down, we relate
such phenomena to Penrose's "Strong Cosmic Censorship Conjecture", and finally
we discuss the questions noted above.


title:
Status and Future of Nuclear Matrix Elements for Neutrinoless
  Double-Beta Decay: A Review

abstract:
  The nuclear matrix elements that govern the rate of neutrinoless double beta
decay must be accurately calculated if experiments are to reach their full
potential. Theorists have been working on the problem for a long time but have
recently stepped up their efforts as ton-scale experiments have begun to look
feasible. Here we review past and recent work on the matrix elements in a wide
variety of nuclear models and discuss work that will be done in the near
future. Ab initio nuclear-structure theory, which is developing rapidly, holds
out hope of more accurate matrix elements with quantifiable error bars.


title: Untraceable VoIP Communication based on DC-nets

abstract:
  Untraceable communication is about hiding the identity of the sender or the
recipient of a message. Currently most systems used in practice (e.g., TOR)
rely on the principle that a message is routed via several relays to obfuscate
its path through the network. However, as this increases the end-to-end latency
it is not ideal for applications like Voice-over-IP (VoIP) communication, where
participants will notice annoying delays if the data does not arrive fast
enough. We propose an approach based on the paradigm of Dining Cryptographer
networks (DC-nets) that can be used to realize untraceable communication within
small groups. The main features of our approach are low latency and resilience
to packet-loss and fault packets sent by malicious players. We consider the
special case of VoIP communication and propose techniques for a P2P
implementation. We expose existing problems and sketch possible future
large-scale systems composed of multiple groups.


title: Neural Machine Translation with Characters and Hierarchical Encoding

abstract:
  Most existing Neural Machine Translation models use groups of characters or
whole words as their unit of input and output. We propose a model with a
hierarchical char2word encoder, that takes individual characters both as input
and output. We first argue that this hierarchical representation of the
character encoder reduces computational complexity, and show that it improves
translation performance. Secondly, by qualitatively studying attention plots
from the decoder we find that the model learns to compress common words into a
single embedding whereas rare words, such as names and places, are represented
character by character.


title:
Nonlinear Structural Vector Autoregressive Models for Inferring
  Effective Brain Network Connectivity

abstract:
  Structural equation models (SEMs) and vector autoregressive models (VARMs)
are two broad families of approaches that have been shown useful in effective
brain connectivity studies. While VARMs postulate that a given region of
interest in the brain is directionally connected to another one by virtue of
time-lagged influences, SEMs assert that causal dependencies arise due to
contemporaneous effects, and may even be adopted when nodal measurements are
not necessarily multivariate time series. To unify these complementary
perspectives, linear structural vector autoregressive models (SVARMs) that
leverage both contemporaneous and time-lagged nodal data have recently been put
forth. Albeit simple and tractable, linear SVARMs are quite limited since they
are incapable of modeling nonlinear dependencies between neuronal time series.
To this end, the overarching goal of the present paper is to considerably
broaden the span of linear SVARMs by capturing nonlinearities through kernels,
which have recently emerged as a powerful nonlinear modeling framework in
canonical machine learning tasks, e.g., regression, classification, and
dimensionality reduction. The merits of kernel-based methods are extended here
to the task of learning the effective brain connectivity, and an efficient
regularized estimator is put forth to leverage the edge sparsity inherent to
real-world complex networks. Judicious kernel choice from a preselected
dictionary of kernels is also addressed using a data-driven approach. Extensive
numerical tests on ECoG data captured through a study on epileptic seizures
demonstrate that it is possible to unveil previously unknown causal links
between brain regions of interest.


title: Reactive Turing Machines with Infinite Alphabets

abstract:
  The notion of Reactive Turing machine (RTM) was proposed as an orthogonal
extension of Turing machines with interaction. RTMs are used to define the
notion of executable transition system in the same way as Turing machines are
used to define the notion of computable function on natural numbers. RTMs
inherited finiteness of all sets involved from Turing machines, and as a
consequence, in a single step, an RTM can only communicate elements from a
finite set of data. Some process calculi, such as the pi-calculus, essentially
depend on an infinite alphabet of actions, and hence it immediately follows
that transition systems specified in these calculi are not executable. On
closer inspection, however, the pi-calculus does not appear to use the infinite
data in a non-computable manner.
  In this paper, we investigate several ways to relax the finiteness
requirement. We start by considering a variant of RTMs in which all sets are
allowed to be countable, and we get a notion of infinitary RTM. Infinitary RTMs
are extremely expressive such that we can hardly use them as a expressiveness
criterion. Then, we refine the model by adding extra restrictions. As a result,
we define a notion of RTM with atoms. It is a more restricted variant of RTMs
in which the sets of actions and data symbols are still allowed to be infinite.
We propose a notion of of nominal executability based on RTMs with atoms, and
show that every effective transition system with atoms is nominally executable.
It will follow that processes definable in the pi-calculus are nominally
executable. In contrast, in the process specification language mCRL2 it is
possible to specify processes that are not nominally executable. Thus, nominal
executability provides a new expressiveness criterion for process calculi.


title: A note on the Schur-finiteness of linear sections

abstract:
  Making use of the recent theory of noncommutative motives, we prove that
Schur-finiteness in the setting of Voevodsky's mixed motives is invariant under
homological projective duality. As an application, we show that the mixed
motives of smooth linear sections of certain (Lagrangian) Grassmannians, spinor
varieties, and determinantal varieties, are Schur-finite. Finally, we upgrade
our applications from Schur-finiteness to Kimura-finiteness.


title: Contravariant Gravity on Poisson Manifolds and Einstein Gravity

abstract:
  A relation between gravity on Poisson manifolds proposed in arXiv:1508.05706
and Einstein gravity is investigated. The compatibility of the Poisson and
Riemann structures defines a unique connection, the contravariant Levi-Civita
connection, and leads to the idea of the contravariant gravity. The
Einstein-Hilbert-type action yields an equation of motion which is written in
terms of the analog of the Einstein tensor, and it includes couplings between
the metric and the Poisson tensor. The study of the Weyl transformation reveals
properties of those interactions. It is argued that this theory can have an
equivalent description as a system of Einstein gravity coupled to matter. As an
example, it is shown that the contravariant gravity on a two-dimensional
Poisson manifold can be described by a real scalar field coupled to the metric
in a specific manner.


title: Decompositions of differential equations from medical imaging

abstract:
  Studying medical imaging, Peter Kuchment and Sergey Lvin encountered an
countable family of differential identities for sine, cosine, and the
exponential function. Specifically if for a smooth function $u$ and a complex
number $\lambda$ the minimal differential equation $u' = \lambda u$ held, then
$u$ satisfied all of their identities (i). If $u" = \lambda^2 u$, then $u$
satisfied all odd-indexed identities (ii). They were unable to determine (iii)
if there were some other pattern as well. We realize their $n$-th identity as a
polynomial $f_{n,\lambda}(u)$ in the variable $u$ that turns out to have
integer coefficients. We construct combinatorial relations on the coefficients
to provide an alternate proof of one of Kuchment and Lvin's results. We also
isolate the part of $f_{n,\lambda}(u)$ that is linear in the variable $u$ to
answer (iii) negatively, and describe how the analysis of the linear polynomial
may connect to the analysis of the whole polynomial.


title: Phase-field crystal model for ordered crystals

abstract:
  We describe a general method to model multicomponent ordered crystals using
the phase-field crystal (PFC) formalism. As a test case, a generic B2 compound
is investigated. We are able to produce a line of either first-order or
second-order order-disorder phase transitions, features that have not been
incorporated in existing PFC approaches. Further, it is found that the only
elastic constant for B2 that depends on ordering is $C_{11}$. This B2 model was
then used to study antiphase boundaries (APBs). The APBs were shown to
reproduce classical mean field results. Dynamical simulations of ordering
across small-angle grain boundaries predict that dislocation cores pin the
evolution of APBs.


title: Fano-Andreev effect in T-shape double-quantum-dot in the Kondo regime

abstract:
  In the present work, we investigate the electronic transport through a
T-shape double quantum dot system coupled to two normal leads and to one
superconducting lead. We explore the interplay between Kondo and Andreev states
due to proximity effects. We find that Kondo resonance is modified by the
Andreev bound states, which manifest through Fano antiresonances in the local
density of states of the embedded quantum dot and normal transmission. This
means that there is a correlation between Andreev bound states and Fano
resonances that is robust under the influence of high electronic correlation.
We have also found that the dominant couplings at the quantum dots are
characterized by a crossover region that defines the range where the Fano-Kondo
and the Andreev-Kondo effect prevail in each quantum dot. Likewise, we find
that the interaction between Kondo and Andreev bound states has a notable
influence on the Andreev transport.


title: Hamiltonicity of planar graphs with a forbidden minor

abstract:
  Tutte showed that $4$-connected planar graphs are Hamiltonian, but it is well
known that $3$-connected planar graphs need not be Hamiltonian. We show that
$K_{2,5}$-minor-free $3$-connected planar graphs are Hamiltonian. This does not
extend to $K_{2,5}$-minor-free $3$-connected graphs in general, as shown by the
Petersen graph, and does not extend to $K_{2,6}$-minor-free $3$-connected
planar graphs, as we show by an infinite family of examples.


title: Prospects for Cosmological Collider Physics

abstract:
  It is generally expected that heavy fields are present during inflation,
which can leave their imprint in late-time cosmological observables. The main
signature of these fields is a small amount of distinctly shaped
non-Gaussianity, which if detected, would provide a wealth of information about
the particle spectrum of the inflationary Universe. Here we investigate to what
extent these signatures can be detected or constrained using futuristic 21-cm
surveys. We construct model-independent templates that extract the
squeezed-limit behavior of the bispectrum, and examine their overlap with
standard inflationary shapes and secondary non-Gaussianities. We then use these
templates to forecast detection thresholds for different masses and couplings
using a 3D reconstruction of modes during the dark ages ($z\sim 30-100$). We
consider interactions of several broad classes of models and quantify their
detectability as a function of the baseline of a dark ages interferometer. Our
analysis shows that there exists the tantalizing possibility of discovering new
particles with different masses and interactions with future 21-cm surveys.


title: B-strings on non-K\"ahlerian manifolds

abstract:
  We explain how to couple topological B-models whose targets are
non-K\"ahlerian manifolds to topological gravity and to thus define
corresponding topological strings. We emphasize the need to take into account
the coupling to the superghost field of topological gravity in order to obtain
a consistent definition of the string model. We also review the importance of
the superghost for correctly interpreting the holomorphic anomaly of the string
amplitudes. We perform our analysis in the BV framework in order to make it
completely gauge independent.


title: Detecting the Elusive Blazar Counter-Jets

abstract:
  Detection of blazar pc scale counter-jets is difficult, but it can provide
invaluable insight into the relativistic effects, radiative processes and the
complex mechanisms of jet production, collimation and accelation in blazars. We
build on recent populations models (optimized using the MOJAVE apparent
velocity and redshift distributions) in order to derive the distribution of
jet-to-counter-jet ratios and the flux densities of the counter-jet at
different frequencies, in an effort to set minimum sensitivity limits required
for existing and future telescope arrays in order to detect these elusive
counter-jets. We find that: for the BL Lacs $5\%$ of their counter-jets have a
flux-density higher than 100mJy, $15\%$ are higher than 10 mJy, and $32\%$ have
higher flux-density than 1 mJy, whereas for the FSRQs $8\%$ have a flux-density
higher than 10mJy, $17\%$ are higher than 1 mJy, and $32\%$ are higher than 0.1
mJy (at 15 GHz). Future telescopes like the SKA and newly operating like
e-MERLIN and JVLA may detect up to $99\%$ of the BL Lac and $77\%$ of the FSRQ
counter-jets. Sources with both low apparent velocity and a low Doppler factor
make prime candidates for counter-jet detection. Combining our findings with
literature values we have identified five such counter-jet detection
candidates. Finally, we discuss possible effects beyond relativistic deboosting
that may complicate the detection of counter-jets and that need to be accounted
for in the interpretation of detections.


title:
TiO2 nanotubes: N-ion implantation at low-dose provides noble-metal-free
  photocatalytic H2-evolution activity

abstract:
  Low-dose nitrogen implantation induces in TiO2 nanotubes a co-catalytic
activity for photocatalytic H2-evolution. The use of an ion implantation
process leads to a N-implanted zone only at the top part of the tubes. The
coupling of this top layer and the underlying non-implanted part of the
nanotubes strongly contributes to an efficient carrier separation and thus to a
significantly enhanced H2 generation.


title:
Neutrino spin and spin-flavour oscillations in transversally moving or
  polarized matter

abstract:
  Studies of an interesting effect of neutrino spin and spin-flavour
oscillations engenders by neutrino weak interactions with the transversally
moving or polarized matter are reviewed.


title:
Hydrogenated anatase: Strong photocatalytic H2 evolution without the use
  of a co-catalyst

abstract:
  In the present work we show, how a high pressure hydrogenation of commercial
anatase or anatase/rutile powder can create a photocatalyst for hydrogen
evolution that is highly effective and stable without the need of any
additional co-catalyst. This activation effect can not be observed for rutile.
For anatase/rutile mixtures, however, a strong synergistic effect is found
(similar to findings commonly observed for noble metal decorated TiO2). ESR
measurements indicate the intrinsic co-catalytic activation of anatase TiO2 to
be due to specific defect centers formed during hydrogenation.


title:
Cosmic Ray Acceleration by a Versatile Family of Galactic Wind
  Termination Shocks

abstract:
  There are two distinct breaks in the cosmic ray (CR) spectrum: the so-called
"knee" around $3 \times 10^{15}$ eV and the so-called "ankle" around $10^{18}$
eV. Diffusive shock acceleration (DSA) at supernova remnant (SNR) shock fronts
is thought to accelerate galactic CRs to energies below the knee, while an
extragalactic origin is presumed for CRs with energies beyond the ankle. CRs
with energies between $3 \times 10^{15}$ and $10^{18}$ eV, which we dub the
"shin," have an unknown origin. It has been proposed that DSA at galactic wind
termination shocks, rather than at SNR shocks, may accelerate CRs to these
energies. This paper uses the galactic wind model of Bustard et al. (2016) to
analyze whether galactic wind termination shocks may accelerate CRs to shin
energies within a reasonable acceleration time and whether such CRs can
subsequently diffuse back to the galaxy. We argue for acceleration times on the
order of 100 Myrs rather than a few billion years, as assumed in some previous
works, and we discuss prospects for magnetic field amplification at the shock
front. Ultimately, we generously assume that the magnetic field is amplified to
equipartition. This formalism allows us to obtain analytic formulae, applicable
to any wind model, for CR acceleration. Even with generous assumptions, we find
that very high wind velocities are required to set up the necessary conditions
for acceleration beyond $10^{17}$ eV. We also estimate the luminosities of CRs
accelerated by outflow termination shocks, including estimates for the Milky
Way wind.


title: On the Origin and Evolution of the Galaxy Stellar Mass Function

abstract:
  Here we explore the evolution of galaxy ensembles at early times by writing
the in situ stellar mass growth of galaxies purely as a stationary stochastic
(e.g., quasi-steady state) process. By combining the mathematics of such
processes with Newtonian gravity and a mean local star formation efficiency, we
show that the stellar mass evolution of galaxy ensembles is directly related to
the average acceleration of baryons onto dark matter halos at the onset of star
formation, with explicit dependencies on initial local matter densities and
halo mass. The density term specifically implies more rapid average rates of
growth in higher density regions of the universe compared to low density
regions, i.e., assembly bias. With this framework, using standard cosmological
parameters, a mean star formation efficiency derived by other authors, and
knowledge of the shape of the cosmological matter power spectrum at small
scales, we analytically derive (1) the characteristic stellar masses of
galaxies (M*), (2) the power-law low-mass slope (alpha) and normalization
(phi*) of the stellar mass function, and (3) the evolution of the stellar mass
function in time over 12.5 > z > 2. Correspondingly, the rise in the cosmic
star formation rate density over these epochs, while the universe can sustain
unabated fueling of star formation, also emerges naturally. All of our findings
are consistent with the deepest available data, including the expectation of
alpha~-7/5; i.e., a stellar mass function low-mass slope that is notably
shallower than that of the halo mass function, and with no systematic
deviations from a mean star formation efficiency with density or mass, nor any
explicit, additional feedback mechanisms. These derivations yield a compelling
richness and complexity but also show that very few astrophysical details are
required to understand the evolution of cosmic ensemble of galaxies at early
times.


title: Two-Loop SL(2) Form Factors and Maximal Transcendentality

abstract:
  Form factors of composite operators in the SL(2) sector of N=4 SYM theory are
studied up to two loops via the on-shell unitarity method. The non-compactness
of this subsector implies the novel feature and technical challenge of an
unlimited number of loop momenta in the integrand's numerator. At one loop, we
derive the full minimal form factor to all orders in the dimensional
regularisation parameter. At two loops, we construct the complete integrand for
composite operators with an arbitrary number of covariant derivatives, and we
obtain the remainder functions as well as the dilatation operator for composite
operators with up to three covariant derivatives. The remainder functions
reveal curious patterns suggesting a hidden maximal uniform transcendentality
for the full form factor. Finally, we speculate about an extension of these
patterns to QCD.


title:
Entanglement entropy of the large $N$ Wilson-Fisher conformal field
  theory

abstract:
  We compute the entanglement entropy of the Wilson-Fisher conformal field
theory (CFT) in 2+1 dimensions with O($N$) symmetry in the limit of large $N$
for general entanglement geometries. We show that the leading large $N$ result
can be obtained from the entanglement entropy of $N$ Gaussian scalar fields
with their mass determined by the geometry. For a few geometries, the universal
part of the entanglement entropy of the Wilson-Fisher CFT equals that of a CFT
of $N$ massless scalar fields. However, in most cases, these CFTs have a
distinct universal entanglement entropy even at $N=\infty$. Notably, for a
semi-infinite cylindrical region it scales as $N^0$, in stark contrast to the
$N$-linear result of the Gaussian fixed point.


title:
The SILCC project --- IV. Impact of dissociating and ionising radiation
  on the interstellar medium and Halpha emission as a tracer of the star
  formation rate

abstract:
  We present three-dimensional radiation-hydrodynamical simulations of the
impact of stellar winds, photoelectric heating, photodissociating and
photoionising radiation, and supernovae on the chemical composition and star
formation in a stratified disc model. This is followed with a sink-based model
for star clusters with populations of individual massive stars. Stellar winds
and ionising radiation regulate the star formation rate at a factor of ~10
below the simulation with only supernova feedback due to their immediate impact
on the ambient interstellar medium after star formation. Ionising radiation
(with winds and supernovae) significantly reduces the ambient densities for
most supernova explosions to rho < 10^-25 g cm^-3, compared to 10^-23 g cm^-3
for the model with only winds and supernovae. Radiation from massive stars
reduces the amount of molecular hydrogen and increases the neutral hydrogen
mass and volume filling fraction. Only this model results in a molecular gas
depletion time scale of 2 Gyr and shows the best agreement with observations.
In the radiative models, the Halpha emission is dominated by radiative
recombination as opposed to collisional excitation (the dominant emission in
non-radiative models), which only contributes ~1-10 % to the total Halpha
emission. Individual massive stars (M >= 30 M_sun) with short lifetimes are
responsible for significant fluctuations in the Halpha luminosities. The
corresponding inferred star formation rates can underestimate the true
instantaneous star formation rate by factors of ~10.


title:
Revealing a spiral-shaped molecular cloud in our galaxy - Cloud
  fragmentation under rotation and gravity

abstract:
  The dynamical processes that control star formation in molecular clouds are
not well understood, and in particular, it is unclear if rotation plays a major
role in cloud evolution. We investigate the importance of rotation in cloud
evolution by studying the kinematic structure of a spiral-shaped Galactic
molecular cloud G052.24+00.74. The cloud belongs to a large filament, and is
stretching over ~ 100 pc above the Galactic disk midplane. The spiral-shaped
morphology of the cloud suggests that the cloud is rotating. We have analysed
the kinematic structure of the cloud, and study the fragmentation and star
formation. We find that the cloud exhibits a regular velocity pattern along
west-east direction - a velocity shift of ~ 10 km/s at a scale of ~ 30 pc. The
kinematic structure of the cloud can be reasonably explained by a model that
assumes rotational support. Similarly to our Galaxy, the cloud rotates with a
prograde motion. We use the formalism of Toomre (1964) to study the cloud's
stability, and find that it is unstable and should fragment. The separation of
clumps can be consistently reproduced assuming gravitational instability,
suggesting that fragmentation is determined by the interplay between rotation
and gravity. Star formation occurs in massive, gravitational bound clumps.


title: Evolving Planck Mass in Classically Scale-Invariant Theories

abstract:
  We consider classically scale-invariant theories with non-minimally coupled
scalar fields, where the Planck mass and the hierarchy of physical scales are
dynamically generated. The classical theories possess a fixed point, where
scale invariance is spontaneously broken. In these theories, however, the
Planck mass becomes unstable in the presence of explicit sources of scale
invariance breaking, such as non-relativistic matter and cosmological constant
terms. We quantify the constraints on such classical models from Big Bang
Nucleosynthesis that lead to an upper bound on the non-minimal coupling and
require trans-Planckian field values. We show that quantum corrections to the
scalar potential can stabilise the fixed point close to the minimum of the
Coleman-Weinberg potential. The time-averaged motion of the evolving fixed
point is strongly suppressed, thus the limits on the evolving gravitational
constant from Big Bang Nucleosynthesis and other measurements do not presently
constrain this class of theories. Field oscillations around the fixed point, if
not damped, contribute to the dark matter density of the Universe.


title:
VoIgt profile Parameter Estimation Routine (VIPER): H I photoionization
  rate at z<0.5

abstract:
  We have developed a parallel code called "VoIgt profile Parameter Estimation
Routine (VIPER)" for automatically fitting the H I Ly-$\alpha$ forest seen in
the spectra of QSOs. We obtained the H I column density distribution function
(CDDF) and line width ($b$) parameter distribution for $z < 0.45$ using spectra
of 82 QSOs obtained using Cosmic Origins Spectrograph and VIPER. Consistency of
these with the existing measurements in the literature validate our code. By
comparing this CDDF with those obtained from hydrodynamical simulation, we
constrain the H I photoionization rate ($\Gamma_{\rm HI}$) at $z < 0.45$ in
four redshift bins. The VIPER, together with the Code for Ionization and
Temperature Evolution (CITE) we have developed for GADGET-2, allows us to
explore parameter space and perform $\chi^2$ minimization to obtain
$\Gamma_{\rm HI}$. We notice that the $b$ parameters from the simulations are
smaller than what are derived from the observations. We show the observed $b$
parameter distribution and $b$ vs $\log {\rm N_{HI}}$ scatter can be reproduced
in simulation by introducing sub-grid scale turbulence. However, it has very
little influence on the derived $\Gamma_{\rm HI}$. The $\Gamma_{\rm HI}(z)$
obtained here, $(3.9 \pm 0.1) \times 10^{-14} \; (1+z)^{4.98 \pm 0.11} \;{\rm
s^{-1}}$, is in good agreement with those derived by us using flux based
statistics in the previous paper. These are consistent with the hydrogen
ionizing ultra-violet (UV) background being dominated mainly by QSOs without
needing any contribution from the non-standard sources of the UV photons.


title: Wait for it: Post-supernova winds driven by delayed radioactive decays

abstract:
  In most astrophysical situations, the radioactive decay of 56Ni to 56Co
occurs via electron capture with a fixed half-life of 6.1 days. However, this
decay rate is significantly slowed when the nuclei are fully ionized because
K-shell electrons are unavailable for capture. In this paper, we explore the
effect of these delayed decays on white dwarfs (WDs) that may survive Type Ia
and Type Iax supernovae (SNe Ia and SNe Iax). The energy released by the
delayed radioactive decays of 56Ni and 56Co drives a persistent wind from the
surviving WD's surface that contributes to the late-time appearance of these
SNe after emission from the bulk of the SN ejecta has faded. We use the stellar
evolution code MESA to calculate the hydrodynamical evolution and resulting
light curves of these winds. Our post-SN Ia models conflict with late-time
observations of SN 2011fe, but uncertainties in our initial conditions prevent
us from ruling out the existence of surviving WD donors. Much better agreement
with observations is achieved with our post-SN Iax bound remnant models,
providing evidence that these explosions are due to deflagrations in accreting
WDs that fail to completely unbind the WDs. Future radiative transfer
calculations and wind models utilizing explosion simulations for more accurate
initial conditions will extend our study of radioactively-powered winds from
post-SN surviving WDs and enable their use as powerful discriminants among the
various SN Ia and SN Iax progenitor scenarios.


title:
Characterising the evolving $K$-band luminosity function using the
  UltraVISTA, CANDELS and HUDF surveys

abstract:
  We present the results of a new study of the K-band galaxy luminosity
function (KLF) at redshifts z<3.75, based on a nested combination of the
UltraVISTA, CANDELS and HUDF surveys. The large dynamic range in luminosity
spanned by this new dataset (3-4 dex over the full redshift range) is
sufficient to clearly demonstrate for the first time that the faint-end slope
of the KLF at z>0.25 is relatively steep (-1.3<alpha<-1.5 for a single
Schechter function), in good agreement with recent theoretical and
phenomenological models. Moreover, based on our new dataset we find that a
double Schechter function provides a significantly improved description of the
KLF at z<2. At redshifts z>0.25 the evolution of the KLF is remarkably smooth,
with little or no evolution evident at faint (M_K>-20.5) or bright magnitudes
(M_K<-24.5). Instead, the KLF is seen to evolve rapidly at intermediate
magnitudes, with the number density of galaxies at M_K~-23 dropping by a factor
of ~5 over the redshift interval 0.25<z<3.75. Motivated by this, we explore a
simple description of the evolving KLF based on a double Schechter function
with fixed faint-end slopes (alpha_1=-0.5, alpha_2=-1.5) and a shared
characteristic magnitude (M_K*). According to this parameterisation, the
normalisation of the component which dominates the faint-end of the KLF remains
approximately constant, with phi*_2 decreasing by only a factor of ~2 between
z~0 and z~3.25. In contrast, the component which dominates the bright end of
the KLF at low redshifts evolves dramatically, becoming essentially negligible
by z~3. Finally, we note that within this parameterisation, the observed
evolution of M_K* between z~0 and z~3.25 is entirely consistent with M_K*
corresponding to a constant stellar mass of M*~5x10^10 Msun at all redshifts.


title:
Partonic structure of neutral pseudoscalars via two photon transition
  form factors

abstract:
  The $\gamma \gamma^\ast \to \eta_{c,b}$ transition form factors are computed
using a continuum approach to the two valence-body bound-state problem in
relativistic quantum field theory, and thereby unified with equivalent
calculations of electromagnetic pion elastic and transition form factors. The
resulting $\gamma \gamma^\ast \to \eta_c$ form factor, $G_{\eta_c}(Q^2)$, is
consistent with available data: significantly, at accessible momentum
transfers, $Q^2 G_{\eta_c}(Q^2)$ lies well below its conformal limit. These
observations confirm that the leading-twist parton distribution amplitudes
(PDAs) of heavy-heavy bound-states are compressed relative to the conformal
limit. A clear understanding of the distribution of valence-quarks within
mesons thus emerges; a picture which connects Goldstone modes, built from the
lightest-quarks in Nature, with systems containing the heaviest valence-quarks
that can now be studied experimentally, and highlights basic facts about
manifestations of mass within the Standard Model.


title:
A Multiply-Imaged z $\sim$ 6.3 Lyman Alpha Emitter candidate behind
  Abell 2261

abstract:
  While the Lyman-$\alpha$ ($\mathrm{Ly}\alpha$) emission line serves as an
important tool in the study of galaxies at $z\lesssim 6$, finding Ly$\alpha$
emitters (LAE) at significantly higher redshifts has been more challenging,
probably because of the increasing neutrality of the intergalactic medium above
$z\sim6$. Galaxies with extremely high rest-frame Ly$\alpha$ equivalent widths,
EW(Ly$\alpha$) $\gtrsim 150$ \AA{}, at $z>6$ are good candidates for Ly$\alpha$
follow-up observations, and can stand out in multiband imaging surveys because
of their unusual colors. We have conducted a photometric search for such
objects in the Cluster Lensing And Supernova survey with Hubble (CLASH), and
report here the identification of three likely gravitationally-lensed images of
a single LAE candidate at $z\sim6.3$, behind the galaxy cluster Abell 2261($z =
0.225$). In the process, we also measured with Keck/MOSFIRE the first
spectroscopic redshift of a multiply-imaged galaxy behind Abell 2261, at $z =
3.337$. This allows us to calibrate the lensing model, which in turn is used to
study the properties of the candidate LAE. Population III galaxy spectral
energy distribution (SED) model fits to the CLASH broadband photometry of the
possible LAE provide a slightly better fit than Population I/II models. The
best fitted model suggests intrinsic EW(Ly$\alpha$) $\approx 160$ \AA{} after
absorption in the interstellar and intergalactic medium. Future spectroscopic
observations will examine this prediction as well as shed more light on the
morphology of this object, which indicates it may be a merger of two smaller
galaxies.


title:
Criteria for gravitational instability and quasi-isolated gravitational
  collapse in turbulent medium

abstract:
  We study the evolution of structures in turbulent, self-gravitating media,
and present an analytical criterion $M_{\rm crit} \approx \epsilon_{\rm
cascade}^{2/3} \eta^{-2/3} G^{-1} l^{5/3}$ (where $M_{\rm crit}$ is the
critical mass, $l$ is the scale, $\epsilon_{\rm cascade}\approx \eta
\sigma_{\rm v}^3 /l $ is the turbulence energy dissipation rate of the ambient
medium, $G$ is the gravitational constant, $\sigma_{\rm v}$ is the velocity
dispersion, $l$ is the scale and $\eta\approx 0.2$ is an efficiency parameter)
for an object to undergo quasi-isolated gravitational collapse. The criterion
also defines the critical scale ($l_{\rm crit} \approx \epsilon_{\rm
cascade}^{1/2} \eta^{-1/2} G^{-3/4} \rho^{-3/4}$) for turbulent gravitational
instability to develop. The analytical formalism explains the size dependence
of the masses of the progenitors of star clusters ($M_{\rm cluster} \sim R_{\rm
cluster}^{1.67}$) in our Galaxy.


title:
The metal enrichment of passive galaxies in cosmological simulations of
  galaxy formation

abstract:
  Massive early-type galaxies have higher metallicities and higher ratios of
$\alpha$ elements to iron than their less massive counterparts. Reproducing
these correlations has long been a problem for hierarchical galaxy formation
theory, both in semi-analytic models and cosmological hydrodynamic simulations.
We show that a simulation in which gas cooling in massive dark haloes is
quenched by radio-mode active galactic nuclei (AGNs) feedback naturally
reproduces the observed trend between $\alpha$/Fe and the velocity dispersion
of galaxies, $\sigma$. The quenching occurs earlier for more massive galaxies.
Consequently, these galaxies complete their star formation before $\alpha$/Fe
is diluted by the contribution from type Ia supernovae. For galaxies more
massive than $\sim 10^{11}~M_\odot$ whose $\alpha$/Fe correlates positively
with stellar mass, we find an inversely correlated mass-metallicity relation.
This is a common problem in simulations in which star formation in massive
galaxies is quenched either by quasar- or radio-mode AGN feedback. The early
suppression of gas cooling in progenitors of massive galaxies prevents them
from recapturing enriched gas ejected as winds. Simultaneously reproducing the
[$\alpha$/Fe]-$\sigma$ relation and the mass-metallicity relation is, thus,
difficult in the current framework of galaxy formation.


title:
The turbulent life of dust grains in the supernova-driven, multi-phase
  interstellar medium

abstract:
  Dust grains are an important component of the interstellar medium (ISM) of
galaxies. We present the first direct measurement of the residence times of
interstellar dust in the different ISM phases, and of the transition rates
between these phases, in realistic hydrodynamical simulations of the
multi-phase ISM. Our simulations include a time-dependent chemical network that
follows the abundances of H^+, H, H_2, C^+ and CO and take into account
self-shielding by gas and dust using a tree-based radiation transfer method.
Supernova explosions are injected either at random locations, at density peaks,
or as a mixture of the two. For each simulation, we investigate how matter
circulates between the ISM phases and find more sizeable transitions than
considered in simple mass exchange schemes in the literature. The derived
residence times in the ISM phases are characterised by broad distributions, in
particular for the molecular, warm and hot medium. The most realistic
simulations with random and mixed driving have median residence times in the
molecular, cold, warm and hot phase around 17, 7, 44 and 1 Myr, respectively.
The transition rates measured in the random driving run are in good agreement
with observations of Ti gas-phase depletion in the warm and cold phases in a
simple depletion model, although the depletion in the molecular phase is
under-predicted. ISM phase definitions based on chemical abundance rather than
temperature cuts are physically more meaningful, but lead to significantly
different transition rates and residence times because there is no direct
correspondence between the two definitions.

categories: astro-ph.GA astro-ph.SR physics.comp-ph physics.flu-dyn


title:
The Ly$\alpha$ emission from high-$z$ galaxies hosting strong Damped
  Ly$\alpha$ systems

abstract:
  We study the average Ly$\alpha$ emission associated with high-$z$ strong (log
$N$(H I) $\ge$ 21) damped Ly$\alpha$ systems (DLAs). We report Ly$\alpha$
luminosities ($L_{\rm Ly\alpha}$) for the full as well as various sub-samples
based on $N$(H I), $z$, $(r-i)$ colours of QSOs and rest equivalent width of Si
II$\lambda$1526 line (i.e., $W_{1526}$). For the full sample, we find $L_{\rm
Ly\alpha}$$< 10^{41} (3\sigma)\ \rm erg\ s^{-1}$ with a $2.8\sigma$ level
detection of Ly$\alpha$ emission in the red part of the DLA trough. The $L_{\rm
Ly\alpha}$ is found to be higher for systems with higher $W_{1526}$ with its
peak, detected at $\geq 3\sigma$, redshifted by about 300-400 $\rm km\ s^{-1}$
with respect to the systemic absorption redshift, as seen in Lyman Break
Galaxies (LBGs) and Ly$\alpha$ emitters. A clear signature of a double-hump
Ly$\alpha$ profile is seen when we consider $W_{1526} \ge 0.4$ \AA\ and $(r-i)
< 0.05$. Based on the known correlation between metallicity and $W_{1526}$, we
interpret our results in terms of star formation rate (SFR) being higher in
high metallicity (mass) galaxies with high velocity fields that facilitates
easy Ly$\alpha$ escape. The measured Ly$\alpha$ surface brightness requires
local ionizing radiation that is 4 to 10 times stronger than the metagalactic
UV background at these redshifts. The relationship between the SFR and surface
mass density of atomic gas seen in DLAs is similar to that of local dwarf and
metal poor galaxies. We show that the low luminosity galaxies will contribute
appreciably to the stacked spectrum if the size-luminosity relation seen for H
I at low-$z$ is also present at high-$z$. Alternatively, large Ly$\alpha$ halos
seen around LBGs could also explain our measurements.


title: Is the dark matter particle its own antiparticle?

abstract:
  We propose a test based on direct detection data that allows to determine if
the dark matter particle is different from its antiparticle. The test requires
the precise measurement of the dark matter spin-independent direct detection
cross sections off $\mathrm{three}$ different nuclei, and consists of
interpreting such signals in terms of self-conjugate (particle $=$
antiparticle) dark matter to see if such interpretation is consistent. If it is
not, the dark matter must be different from its antiparticle. We illustrate
this procedure for two sets of target nuclei, $\mathrm{\{Xe, Ar, Si\}}$ and
$\mathrm{\{Xe, Ar, Ge\}}$, identifying the regions of the parameter space where
it is particularly feasible. Our results indicate that future signals in direct
detection experiments, if sufficiently accurate, might be used to establish
that the dark matter particle is not its own antiparticle --a major step
towards the determination of the fundamental nature of the dark matter.


title: Exotic colored scalars at the LHC

abstract:
  We study the phenomenology of exotic color-triplet scalar particles $X$ with
charge $|Q|=2/3, 4/3,5/3,7/3,8/3$ and $10/3$. If $X$ is a non-singlet of
$SU(2)_W$ representation, mass splitting within the multiplet allows for
cascade decays of the members into the lightest state. We study examples where
the lightest state, in turn, decays into a three-body $W^\pm jj$ final state,
and show that in such case the entire multiplet is compatible with existing
direct collider searches and indirect precision tests down to $m_X\sim250$~GeV.
However, bound states $S$, made of $XX^\dag$ pairs at $m_S\approx2m_X$, form
under rather generic conditions and their decay to diphoton can be the first
discovery channel of the model. Furthermore, for $SU(2)_W$-non-singlets, the
mode $S\to W^+W^-$ may be observable and the width of $S\to\gamma\gamma$ and
$S\to jj$ may appear large as a consequence of mass splittings within the
$X$-multiplet. As an example we study in detail the case of an $SU(2)_W$
quartet, finding that $m_X\simeq450$~GeV is allowed by all current searches.


title: Constraining axionlike particles using the distance-duality relation

abstract:
  One of the fundamental results used in observational cosmology is the
distance duality relation (DDR), which relates the luminosity distance, $D_L$,
with angular diameter distance, $D_A$, at a given redshift $z$. We employ the
observed limits of this relation to constrain the coupling of axion like
particles (ALPs) with photons. With our detailed $3D$ ALP-photon mixing
simulation in standard $\Lambda$CDM universe and latest DDR limits observed in
Holand \& Barros (2016) we limit the coupling constant $g_{\phi}\le 6 \times
10^{-13} GeV^{-1}\left(\frac{nG}{\langle B \rangle_{\rm Mpc}}\right)$ for ALPs
of mass $\le 10^{-15}$ eV. The DDR observations can provide very stringent
constraint on ALPs mixing in future. Also any deviation in DDR can be
conventionally explained as photons decaying to axions or vice-versa.


title:
A Novel Averaging Technique for Discrete Entropy-Stable Dissipation
  Operators for Ideal MHD

abstract:
  Entropy stable schemes can be constructed with a specific choice of the
numerical flux function. First, an entropy conserving flux is constructed.
Secondly, an entropy stable dissipation term is added to this flux to guarantee
dissipation of the discrete entropy. Present works in the field of entropy
stable numerical schemes are concerned with thorough derivations of entropy
conservative fluxes for ideal MHD. However, as we show in this work, if the
dissipation operator is not constructed in a very specific way, it cannot lead
to a generally stable numerical scheme.
  The two main findings presented in this paper are that the entropy conserving
flux of Ismail & Roe can easily break down for certain initial conditions
commonly found in astrophysical simulations, and that special care must be
taken in the derivation of a discrete dissipation matrix for an entropy stable
numerical scheme to be robust.
  We present a convenient novel averaging procedure to evaluate the entropy
Jacobians of the ideal MHD and the compressible Euler equations that yields a
discretization with favorable robustness properties.


title:
Assessment of the Information Content of the Power Spectrum and
  Bispectrum

abstract:
  The covariance matrix of the matter and halo power spectrum and bispectrum
are studied. Using a large suite of simulations, we find that the
non-Gaussianity in the covariance is significant already at mildly nonlinear
scales. We compute the leading disconnected non-Gaussian correction to the
matter bispectrum covariance using perturbation theory, and find that the
corrections result in good agreement in the mildly nonlinear regime. The shot
noise contribution to the halo power spectrum and bispectrum covariance is
computed using the Poisson model, and the model yields decent agreement with
simulation results. However, when the shot noise is estimated from the
individual realization, which is usually done in reality, we find that the halo
covariance is substantially reduced and gets close to the Gaussian covariance.
This is because most of the non-Gaussianity in the covariance arises from the
fluctuations in the Poisson shot noise. We use the measured non-Gaussian
covariance to access the information content of the power spectrum and
bispectrum. The signal-to-noise ratio, S/N, of the matter and halo power
spectrum levels off in the mildly nonlinear regime, $k \sim 0.1 - 0.2
\,\mathrm{Mpc} h^{-1}$. In the nonlinear regime the S/N of the matter and halo
bispectrum increases but much slower than the Gaussian results suggest. We find
that both the S/N for power spectrum and bispectrum are overestimated by the
Gaussian covariances, but the problem being much more serious for the
bispectrum. Because the bispectrum is affected strongly by nonlinearity and
shot noise, inclusion of the bispectrum only adds modest amount of S/N compared
to that of the power spectrum.


title: Parameter spaces for algebraic equivalence

abstract:
  A cycle is algebraically trivial if it can be exhibited as the difference of
two fibers in a family of cycles parameterized by a smooth scheme. Over an
algebraically closed field, it is a result of Weil that it suffices to consider
families of cycles parameterized by curves, or by abelian varieties. In this
paper, we extend these results to arbitrary base fields. The strengthening of
these results turns out to be a key step in our work elsewhere extending
Murre's results on algebraic representatives for varieties over algebraically
closed fields to arbitrary perfect fields.


title:
A Call for New Physics : The Muon Anomalous Magnetic Moment and Lepton
  Flavor Violation

abstract:
  We review how the muon anomalous magnetic moment ($g-2$) and the quest for
lepton flavor violation are intimately correlated. Indeed the decay $\mu \to e
\gamma$ is induced by the same amplitude for different choices of in- and
outgoing leptons. In this work, we try to address some intriguing questions
such as: Which hierarchy in the charged lepton sector one should have in order
to reconcile possible signals coming simultaneously from $g-2$ and lepton
flavor violation? What can we learn if the $g-2$ anomaly is confirmed by the
upcoming flagship experiments at FERMILAB and J-PARC, and no signal is seen in
the decay $\mu \rightarrow e\gamma$ in the foreseeable future? On the other
hand, if the $\mu \rightarrow e\gamma$ decay is seen in the upcoming years, do
we need to necessarily observe a signal also in $g-2$?. In this attempt, we
generally study the correlation between these observables in a detailed
analysis of simplified models. We derive master integrals and fully analytical
and exact expressions for both phenomena, and adress other flavor violating
signals. We investigate under which conditions the observations can be made
compatible and discuss their implications. Lastly, we discuss in this context
several extensions of the SM, such as the Minimal Supersymmetric Standard
Model, Left-Right symmetric model, $B-L$ model, scotogenic model, two Higgs
doublet model, Zee-Babu model, 331 model, and $L_{\mu}-L_{\tau}$, dark photon,
seesaw models type~I, II and III, and also address the interplay with $\mu \to
eee$ decay and $\mu-e$ conversion.


title: A composite tale of two right-handed neutrinos

abstract:
  In this work, we develop a model for Higgs-like composites based on two
generations of right handed neutrinos which condense. We analyze the
Spontaneous Symmetry Breaking of the theory with two explicit breakings,
setting the different scales of the model and obtaining massive bosons as a
result. Finally, we calculate the gravitational wave imprint left by the phase
transition associated to the symmetry breaking of a generic potential dictated
by the symmetries of the composites.


title:
Large bulk photovoltaic effect and spontaneous polarization of
  single-layer monochalcogenides

abstract:
  We use a first-principles density functional theory approach to calculate the
shift current and linear absorption of uniformly illuminated single-layer Ge
and Sn monochalcogenides. We predict strong absorption in the visible spectrum
and a large effective three-dimensional shift current ($\sim$100 $\mu$A/V$^2$),
larger than has been previously observed in other polar systems. Moreover, we
show that the integral of the shift-current tensor is correlated to the large
spontaneous effective three-dimensional electric polarization ($\sim$1.9
C/m$^2$). Our calculations indicate that the shift current will be largest in
the visible spectrum, suggesting that these monochalcogenides may be promising
for polar optoelectronic devices. A Rice-Mele tight-binding model is used to
rationalize the shift-current response for these systems, and its dependence on
polarization, in general terms with implications for other polar materials


title: Scaling Laws of Passive-Scalar Diffusion in the Interstellar Medium

abstract:
  Passive scalar mixing (metals, molecules, etc.) in the turbulent interstellar
medium (ISM) is critical for abundance patterns of stars and clusters, galaxy
and star formation, and cooling from the circumgalactic medium. However, the
fundamental scaling laws remain poorly understood in the highly supersonic,
magnetized, shearing regime relevant for the ISM. We therefore study the full
scaling laws governing passive-scalar transport in idealized simulations of
supersonic turbulence. Using simple phenomenological arguments for the
variation of diffusivity with scale based on Richardson diffusion, we propose a
simple fractional diffusion equation to describe the turbulent advection of an
initial passive scalar distribution. These predictions agree well with the
measurements from simulations, and vary with turbulent Mach number in the
expected manner, remaining valid even in the presence of a large-scale shear
flow (e.g. rotation in a galactic disk). The evolution of the scalar
distribution is not the same as obtained using simple, constant "effective
diffusivity" as in Smagorinsky models, because the scale-dependence of
turbulent transport means an initially Gaussian distribution quickly develops
highly non-Gaussian tails. We also emphasize that these are mean scalings that
only apply to ensemble behaviors (assuming many different, random scalar
injection sites): individual Lagrangian "patches" remain coherent
(poorly-mixed) and simply advect for a large number of turbulent flow-crossing
times.

categories: astro-ph.GA math.NA physics.comp-ph physics.flu-dyn


title: Di-boson signatures as Standard Candles for Partial Compositeness

abstract:
  Composite Higgs Models are often constructed including fermionic top partners
with a mass around the TeV scale, with the top partners playing the role of
stabilizing the Higgs potential and enforcing partial compositeness for the top
quark. A class of models of this kind can be formulated in terms of fermionic
strongly coupled gauge theories. A common feature they all share is the
presence of specific additional scalar resonances, namely two neutral singlets
and a colored octet, described by a simple effective Lagrangian. We study the
phenomenology of these scalars, both in a model independent and model dependent
way, including the bounds from all the available searches in the relevant
channels with di-boson and di-top final states. We develop a generic framework
which can be used to constrain any model containing pseudo-scalar singlets or
octets. Using it, we find that such signatures provide strong bounds on the
compositeness scale complementary to the traditional EWPT and Higgs couplings
deviations. In many cases a relatively light scalar can be on the verge of
discovery as a first sign of new physics.


title: Defects of liquid crystals with variable degree of orientation

abstract:
  We prove that the zero set of a minimizer of the modified Ericksen energy for
nematic liquid crystals with variable degree of orientation consists locally of
isolated points and a finite union of H\"older continuous curves with only
finitely many crossings.


title:
Nonlinear molecular deformations give rise to stress stiffening,
  yielding and non-uniform stress propagation in actin networks

abstract:
  We use optical tweezers microrheology and fluorescence microscopy to apply
nonlinear microscale strains to entangled and crosslinked actin networks, and
measure the resulting stress and actin filament deformations. We couple
nonlinear stress response and subsequent relaxation to the velocity profiles of
individual fluorescent-labeled actin segments at varying times throughout the
strain and varying distances from the strain path to determine the underlying
molecular dynamics that give rise to the debated nonlinear response and stress
propagation of crosslinked and entangled actin networks at the microscale. We
show that initial stress stiffening arises from acceleration of strained
filaments due to molecular extension along the strain, while softening and
yielding is coupled to filament deceleration, halting and recoil. We
demonstrate a surprising non-monotonic dependence of velocity profiles on
crosslinker concentration. Namely, networks with no crosslinks or substantial
crosslinks both exhibit fast initial filament velocities and reduced molecular
recoil while intermediate crosslinker concentrations display reduced velocities
and increased recoil. We show that these collective results are due to a
balance of network elasticity and transient crosslinker unbinding and
rebinding. We further show that elasticity and relaxation timescales display an
exponential dependence on crosslinker concentration that reveal that crosslinks
dominate entanglement dynamics when the length between crosslinkers becomes
smaller than the length between entanglements. In accord with recent
simulations, our relaxation dynamics demonstrate that post-strain stress can be
long-lived in crosslinked networks by distributing stress to a small fraction
of highly-strained connected filaments that span the network and sustain the
load, thereby allowing the rest of the network to recoil and relax.


title: Efficient numerical solution to vacuum decay with many fields

abstract:
  Finding numerical solutions describing bubble nucleation is notoriously
difficult in more than one field space dimension. Traditional shooting methods
fail because of the extreme non-linearity of field evolution over a macroscopic
distance as a function of initial conditions. Minimization methods tend to
become either slow or imprecise for larger numbers of fields due to their
dependence on the high dimensionality of discretized function spaces. We
present a new method for finding solutions which is both very efficient and
able to cope with the non-linearities. Our method directly integrates the
equations of motion except at a small number of junction points, so we do not
need to introduce a discrete domain for our functions. The method, based on
multiple shooting, typically finds solutions involving three fields in under a
minute, and can find solutions for eight fields in about an hour. We include a
numerical package for Mathematica which implements the method described here.


title:
Structure and Physical Conditions in the Huygens Region of the Orion
  Nebula

abstract:
  HST images, MUSE maps of emission-lines, and an atlas of high velocity
resolution emission-line spectra have been used to establish for the firrst
time correlations of the electron temperature, electron density, radial
velocity, turbulence, and orientation within the main ionization front of the
nebula. From the study of the combined properties of multiple features, it is
established that variations in the radial velocity are primarily caused by the
photo-evaporating ionization front being viewed at different angles. There is a
progressive increase of the electron temperature and density with decreasing
distance from the dominant ionizing star Theta1 Ori C. The product of these
characteristics (NexTe) is the most relevant parameter in modeling a
blister-type nebula like the Huygens Region, where this quantity should vary
with the surface brightness in Halpha. Several lines of evidence indicate that
small-scale structure and turbulence exists down to the level of our resolution
of a few arcseconds. Although photo-evaporative ow must contribute at some
level to the well-known non-thermal broadening of the emission lines,
comparison of quantitative predictions with the observed optical line widths
indicate that it is not the major additive broad- ening component. Derivation
of Te values for H+ from radio+optical and optical-only ionized hydro- gen
emission showed that this temperature is close to that derived from [Nii] and
that the transition from the well-known at extinction curve that applies in the
Huygens Region to a more normal steep extinction curve occurs immediately
outside of the Bright Bar feature of the nebula.


title:
H-theorem and Thermodynamics for generalized entropies that depend only
  on the probability

abstract:
  We consider a previously proposed non-extensive statistical mechanics in
which the entropy depends only on the probability, this was obtained from a
f(\beta) distribution and its corresponding Boltzmann factor. We show that the
first term correcting the usual entropy also arises from several f(\beta)
distributions, we also construct the corresponding H-function and demonstrate
that a generalized H-theorem is fulfilled. Furthermore, expressing this
H-function as function of the simplest Maxwellian state we find, up to a first
approximation some modified thermodynamic quantities for an ideal gas. In order
to gain some insight about the behavior of the proposed generalized statistics,
we present some simulation results for the case of a square-well and
Lennard-Jones potentials, showing that an effective repulsive interaction is
obtained with the new formalism.


title: Standard Model Background of the Cosmological Collider

abstract:
  The inflationary universe can be viewed as a "Cosmological Collider" with
energy of Hubble scale, producing very massive particles and recording their
characteristic signals in primordial non-Gaussianities. To utilize this
collider to explore any new physics at very high scales, it is a prerequisite
to understand the background signals from the particle physics Standard Model.
In this paper we describe the Standard Model background of the Cosmological
Collider.


title: When do Correlations Increase with Firing Rate?

abstract:
  A central question in neuroscience is to understand how noisy firing patterns
are used to transmit information. Because neural spiking is noisy, spiking
patterns are often quantified via pairwise correlations, or the probability
that two cells will spike coincidentally, above and beyond their baseline
firing rate. One observation frequently made in experiments, is that
correlations can increase systematically with firing rate. Theoretical studies
have determined that stimulus-dependent correlations that increase with firing
rate can have beneficial effects on information coding; however, we still have
an incomplete understanding of what circuit mechanisms do, or do not, produce
this correlation-firing rate relationship.
  Here, we study the relationship between pairwise correlations and firing
rates in recurrently coupled excitatory-inhibitory spiking networks with
conductance-based synapses. We found that with stronger excitatory coupling, a
positive relationship emerges between pairwise correlations and firing rates.
To explain these findings, we used linear response theory to predict the full
correlation matrix and to decompose correlations in terms of graph motifs. We
then used this decomposition to explain why covariation of correlations with
firing rate -- a relationship previously explained in feedforward networks
driven by correlated input -- emerges in some recurrent networks but not in
others. Furthermore, when correlations covary with firing rate, this
relationship is reflected in low-rank structure in the correlation matrix.


title:
Euclidean distance matrix completion and point configurations from the
  minimal spanning tree

abstract:
  The paper introduces a special case of the Euclidean distance matrix
completion problem (edmcp) of interest in statistical data analysis where only
the minimal spanning tree distances are given and the matrix completion must
preserve the minimal spanning tree. Two solutions are proposed, one an
adaptation of a more general method based on a dissimilarity parameterized
formulation, the other an entirely novel method which constructs the point
configuration directly through a guided random search. These methods as well as
three standard edcmp methods are described and compared experimentally on real
and synthetic data. It is found that the constructive method given by the
guided random search algorithm clearly outperforms all others considered here.
Notably, standard methods including the adaptation force peculiar, and
generally unwanted, geometric structure on the point configurations their
completions produce.


title: Completeness of the Nearby White Dwarf Sample: Let Us Count the Ways

abstract:
  We have recently extended our ongoing survey of the local white dwarf
population, effectively doubling the sample volume. Based upon the latest
distance determinations, Holberg et al. (2016) estimated the present 20 pc and
25 pc samples were about 86 and 68 percent complete, respectively. Here we
examine how the completeness of the 25 pc sample depends upon other observables
such as apparent magnitude, proper motion, photometric color index, etc. The
results may provide additional clues to why Sirius-Like systems are
underrepresented in the extended 25 pc sample and how additional nearby single
white dwarf stars may be found.


title:
An Approach to Speed-up the Word Sense Disambiguation Procedure through
  Sense Filtering

abstract:
  In this paper, we are going to focus on speed up of the Word Sense
Disambiguation procedure by filtering the relevant senses of an ambiguous word
through Part-of-Speech Tagging. First, this proposed approach performs the
Part-of-Speech Tagging operation before the disambiguation procedure using
Bigram approximation. As a result, the exact Part-of-Speech of the ambiguous
word at a particular text instance is derived. In the next stage, only those
dictionary definitions (glosses) are retrieved from an online dictionary, which
are associated with that particular Part-of-Speech to disambiguate the exact
sense of the ambiguous word. In the training phase, we have used Brown Corpus
for Part-of-Speech Tagging and WordNet as an online dictionary. The proposed
approach reduces the execution time upto half (approximately) of the normal
execution time for a text, containing around 200 sentences. Not only that, we
have found several instances, where the correct sense of an ambiguous word is
found for using the Part-of-Speech Tagging before the Disambiguation procedure.


title: Iterative Refinement for Machine Translation

abstract:
  Existing machine translation decoding algorithms generate translations in a
strictly monotonic fashion and never revisit previous decisions. As a result,
earlier mistakes cannot be corrected at a later stage. In this paper, we
present a translation scheme that starts from an initial guess and then makes
iterative improvements that may revisit previous decisions. We parameterize our
model as a convolutional neural network that predicts discrete substitutions to
an existing translation based on an attention mechanism over both the source
sentence as well as the current translation output. By making less than one
modification per sentence, we improve the output of a phrase-based translation
system by up to 0.4 BLEU on WMT15 German-English translation.


title: Combinatorial Multi-Armed Bandit with General Reward Functions

abstract:
  In this paper, we study the stochastic combinatorial multi-armed bandit
(CMAB) framework that allows a general nonlinear reward function, whose
expected value may not depend only on the means of the input random variables
but possibly on the entire distributions of these variables. Our framework
enables a much larger class of reward functions such as the $\max()$ function
and nonlinear utility functions. Existing techniques relying on accurate
estimations of the means of random variables, such as the upper confidence
bound (UCB) technique, do not work directly on these functions. We propose a
new algorithm called stochastically dominant confidence bound (SDCB), which
estimates the distributions of underlying random variables and their
stochastically dominant confidence bounds. We prove that SDCB can achieve
$O(\log{T})$ distribution-dependent regret and $\tilde{O}(\sqrt{T})$
distribution-independent regret, where $T$ is the time horizon. We apply our
results to the $K$-MAX problem and expected utility maximization problems. In
particular, for $K$-MAX, we provide the first polynomial-time approximation
scheme (PTAS) for its offline problem, and give the first $\tilde{O}(\sqrt T)$
bound on the $(1-\epsilon)$-approximation regret of its online problem, for any
$\epsilon>0$.