title: M31 globular cluster structures and the presence of X-ray binaries

abstract:
  [Abridged] M31 has several times more globular clusters (GCs) than the Milky
Way. It contains a correspondingly larger number of low mass X-ray binaries
(LMXBs) associated with GCs, and can be used to investigate the GC properties
which lead to X-ray binary formation. The best tracer of the spatial structure
of M31 GCs is high-resolution imaging from the Hubble Space Telescope, and we
have used HST data to derive structural parameters for 29 LMXB-hosting M31 GCs.
These measurements are combined with structural parameters from the literature
for a total of 41 (of 50 known) LMXB GCs and a comparison sample of 65 non-LMXB
GCs. Structural parameters measured in blue bandpasses are found to show
smaller core radii and higher concentrations than those measured in red
bandpasses; this difference is enhanced in LMXB clusters and could be related
to stellar population differences. Clusters with LMXBs show higher collision
rates for their mass compared to those without LMXBs and collision rates
estimated at the core radius show larger offsets than rates estimated at the
half-light radius. These results are consistent with the dynamical formation
scenario for LMXBs. A logistic regression analysis finds that, as expected, the
probability of a GC hosting an LMXB increases with increasing collision rate
and proximity to the galaxy center. The same analysis finds that P(LMXB)
decreases with increasing GC mass at a fixed collision rate, although we
caution that this could be due to sample selection effects. Metallicity is
found to be a less important predictor of P(LMXB) than collision rate, mass, or
distance, even though LMXB GCs have a higher metallicity on average. This may
be due to the interaction of location and metallicity: a sample of M31 LMXBs
with a greater range in galactocentric distance would likely contain more
metal-poor GCs and make it possible to disentangle the two effects.


title: Extracting sigma_effective from the LHCb double-charm measurement

abstract:
  We discuss various issues related to the definition of single and double open
charm cross sections. We conclude that LHCb's extraction of sigma_effective,
the effective cross section for double-parton scattering, is too large by a
factor of two. This correction brings the data from open-charm pairs closer to
that from J/psi plus open charm and jet production.


title:
Robust Iterative Interference Alignment for Cellular Networks with
  Limited Feedback

abstract:
  In theory coordinated multi-point transmission (CoMP) promises vast gains in
spectral efficiency. But industrial field trials show rather disappointing
throughput gains, whereby the major limiting factor is proper sharing of
channel state information. Many recent papers consider this so-called limited
feedback problem in the context of CoMP. Usually taking the assumptions: 1)
infinite SNR regime, 2) no user selection and 3) ideal link adaptation;
rendering the analysis too optimistic. In this paper we make a step forward
towards a more realistic assessment of the limited feedback problem by
introducing an improved metric for the performance evaluation which better
captures the throughput degradation. We find the relevant scaling laws (lower
and upper bounds) and how that they are different from existing ones. Moreover,
we provide a robust iterative interference alignment algorithm and
corresponding feedback strategies achieving the obtained scaling laws. The main
idea is that instead of sending the complete channel matrix each user fixes a
receive filter and feeds back a quantized version of the effective channel.
Finally we underline our findings with simulations for the proposed system.


title: On some additive problems in number theory (v.3)

abstract:
  In this article we present method of solving some additive problems with
primes. The method may be employed to the Goldbach-Euler conjecture and the
twin primes conjecture. The presented method also makes it possible to obtain
some interesting results related to the densities of sequences. The method is
based on the direct construction of the Eratosthenes-type double sieve and does
not use empirical and heuristic reasoning.


title:
Exploring Inequality Violations by Classical Hidden Variables
  Numerically

abstract:
  There are increasingly suggestions for computer simulations of quantum
statistics which try to violate Bell type inequalities via classical, common
cause correlations. The Clauser-Horne-Shimony-Holt (CHSH) inequality is very
robust. However, we argue that with the Einstein-Podolsky-Rosen setup, the CHSH
is inferior to the Bell inequality, although and because the latter must assume
anti-correlation of entangled photon singlet states. We simulate how often
quantum behavior violates both inequalities, depending on the number of
photons. Violating Bell 99% of the time is argued to be an ideal benchmark. We
present hidden variables that violate the Bell and CHSH inequalities with 50%
probability, and ones which violate Bell 85% of the time when missing 13%
anti-correlation. We discuss how to present the quantum correlations to a wide
audience and conclude that, when defending against claims of hidden
classicality, one should demand numerical simulations and insist on
anti-correlation and the full amount of Bell violation. This preprint version
adds a section on realisms and shows the actual programs with output.


title:
Thermodynamic assessment of probability distribution divergencies and
  Bayesian model comparison

abstract:
  Within path sampling framework, we show that probability distribution
divergences, such as the Chernoff information, can be estimated via
thermodynamic integration. The Boltzmann-Gibbs distribution pertaining to
different Hamiltonians is implemented to derive tempered transitions along the
path, linking the distributions of interest at the endpoints. Under this
perspective, a geometric approach is feasible, which prompts intuition and
facilitates tuning the error sources. Additionally, there are direct
applications in Bayesian model evaluation. Existing marginal likelihood and
Bayes factor estimators are reviewed here along with their stepping-stone
sampling analogues. New estimators are presented and the use of compound paths
is introduced.


title:
A Fast Alternating Minimization Algorithm for Total Variation Deblurring
  Without Boundary Artifacts

abstract:
  Recently, a fast alternating minimization algorithm for total variation image
deblurring (FTVd) has been presented by Wang, Yang, Yin, and Zhang [{\em SIAM
J. Imaging Sci.}, 1 (2008), pp. 248--272]. The method in a nutshell consists of
a discrete Fourier transform-based alternating minimization algorithm with
periodic boundary conditions and in which two fast Fourier transforms (FFTs)
are required per iteration. In this paper, we propose an alternating
minimization algorithm for the continuous version of the total variation image
deblurring problem. We establish convergence of the proposed continuous
alternating minimization algorithm. The continuous setting is very useful to
have a unifying representation of the algorithm, independently of the discrete
approximation of the deconvolution problem, in particular concerning the
strategies for dealing with boundary artifacts. Indeed, an accurate restoration
of blurred and noisy images requires a proper treatment of the boundary. A
discrete version of our continuous alternating minimization algorithm is
obtained following two different strategies: the imposition of appropriate
boundary conditions and the enlargement of the domain. The first one is
computationally useful in the case of a symmetric blur, while the second one
can be efficiently applied for a nonsymmetric blur. Numerical tests show that
our algorithm generates higher quality images in comparable running times with
respect to the Fast Total Variation deconvolution algorithm.


title: Accuracy of analytical models of the large-scale matter distribution

abstract:
  We investigate the possible accuracy that can be reached by analytical models
for the matter density power spectrum and correlation function. Using a
realistic description of the power spectrum that combines perturbation theory
with a halo model, we study the convergence rate of several perturbative
expansion schemes and the impact of nonperturbative effects, as well as the
sensitivity to phenomenological halo parameters. We check that the simple
reorganization of the standard perturbative expansion, with a Gaussian damping
prefactor, provides a well-ordered convergence and a finite correlation
function that yields a percent accuracy at the baryon acoustic oscillation peak
(as soon as one goes to second order). Lagrangian-space expansions are somewhat
more efficient, when truncated at low orders, but may diverge at high orders.
We find that whereas the uncertainty on the halo-profile mass-concentration
relation is not a strong limitation, the uncertainty on the halo mass function
can severely limit the accuracy of theoretical predictions for $P(k)$ (this
also applies to the power spectra measured in numerical simulations). The
real-space correlation function provides a better separation between
perturbative and nonperturbative effects, which are restricted to $x \lesssim
10 h^{-1}$Mpc at all redshifts.


title:
Apparent criticality and calibration issues in the Hawkes self-excited
  point process model: application to high-frequency financial data

abstract:
  We present a careful analysis of possible issues on the application of the
self-excited Hawkes process to high-frequency financial data. We carefully
analyze a set of effects leading to significant biases in the estimation of the
"criticality index" n that quantifies the degree of endogeneity of how much
past events trigger future events. We report a number of model biases that are
intrinsic to the estimation of brnaching ratio (n) when using power law memory
kernels. We demonstrate that the calibration of the Hawkes process on mixtures
of pure Poisson process with changes of regime leads to completely spurious
apparent critical values for the branching ratio (n~1) while the true value is
actually n=0. More generally, regime shifts on the parameters of the Hawkes
model and/or on the generating process itself are shown to systematically lead
to a significant upward bias in the estimation of the branching ratio. We also
demonstrate the importance of the preparation of the high-frequency financial
data and give special care to the decrease of quality of the timestamps of tick
data due to latency and grouping of messages to packets by the stock exchange.
Altogether, our careful exploration of the caveats of the calibration of the
Hawkes process stresses the need for considering all the above issues before
any conclusion can be sustained. In this respect, because the above effects are
plaguing their analyses, the claim by Hardiman, Bercot and Bouchaud (2013) that
financial market have been continuously functioning at or close to criticality
(n~1) cannot be supported. In contrast, our previous results on E-mini S&P 500
Futures Contracts and on major commodity future contracts are upheld.


title:
Ripple field losses in DC biased superconductors: simulations and
  comparison with measurements

abstract:
  For example in some supercondcuting generators, motors and power transmission
cables the superconductor experiences a changing magnetic field in a DC
background. Simulating the losses caused by this AC ripple field is an
important task from the application design point of view. In this work, we
compare two formulations, the $H$-formulation and the minimum magnetic energy
variation (the MMEV-formulation), based on the eddy current model (ECM) and the
critical state model (CSM), respectively, in simulating ripple field losses in
a DC biased coated conductor tape. Furthermore, we compare our simulation
results with measurements. We investigate the frequency-dependence of the
hysteresis loss predictions of the power law based ECM and verify by a
measurement, that in DC use, ECM clearly over-estimates the homogenization of
the current density profile in the coated conductor tape: the relaxation of the
local current density is not nearly as prominent in the measurement as it is in
the simulation. Hence, we suggest that the power law resistivity, used as the
\emph{local} relation between the electric field intensity ${\bf E}$ and
current density ${\bf J}$ in ECM, is not an intrinsic property of
high-temperature superconductors. The difference between the models manifests
itself as discrepancies in ripple field loss simulations in very low AC fields
with significant DC fields or currents involved. The results also show,
however, that for many practical situations, CSM and ECM are both eligible
models for ripple field loss simulations.


title:
On mathematical and physical principles of transformations of the
  coherent radar backscatter matrix

abstract:
  The congruential rule advanced by Graves for polarization basis
transformation of the radar backscatter matrix is now often misinterpreted as
an example of consimilarity transformation. However, consimilarity
transformations imply a physically unrealistic antilinear time-reversal
operation. This is just one of the approaches found in literature to the
description of transformations where the role of conjugation has been
misunderstood. In this paper, the different approaches are examined in
particular in respect to the role of conjugation. In order to justify and
correctly derive the congruential rule for polarization basis transformation
and properly place the role of conjugation, the origin of the problem is traced
back to the derivation of the antenna hight from the transmitted field. In
fact, careful consideration of the role played by the Green's dyadic operator
relating the antenna height to the transmitted field shows that, under general
unitary basis transformation, it is not justified to assume a scalar
relationship between them. Invariance of the voltage equation shows that
antenna states and wave states must in fact lie in dual spaces, a distinction
not captured in conventional Jones vector formalism. Introducing spinor
formalism, and with the use of an alternate spin frame for the transmitted
field a mathematically consistent implementation of the directional wave
formalism is obtained. Examples are given comparing the wider generality of the
congruential rule in both active and passive transformations with the
consimilarity rule.


title: Prospect Agents and the Feedback Effect on Price Fluctuations

abstract:
  A microeconomic approach is proposed to derive the fluctuations of risky
asset price, where the market participants are modeled as prospect trading
agents. As asset price is generated by the temporary equilibrium between demand
and supply, the agents' trading behaviors can affect the price process in turn,
which is called the feedback effect. The prospect agents make actions based on
their reactions to gains and losses, and as a consequence of the feedback
effect, a relationship between the agents' trading behavior and the price
fluctuations is constructed, which explains the implied volatility skew and
smile observed in actual market.


title: Practical Aspects of the Bitcoin System

abstract:
  Digital payment schemes show an ever increasing importance. Out of the
countless different schemes available this article focuses on the popular
Bitcoin system. The authors provide a description of Bitcoin's unique
technological basis and its accompanying ecosystem of users, miners, trading
platforms and vendors. Furthermore, this article discusses Bitcoin's
currency-like features and the first regulatory actions take in the European
Union and in the United States of America.


title: Infinite Previsions and Finitely Additive Expectations

abstract:
  We give an extension of de Finetti's concept of coherence to unbounded (but
real-valued) random variables that allows for gambling in the presence of
infinite previsions. We present a finitely additive extension of the Daniell
integral to unbounded random variables that we believe has advantages over
Lebesgue-style integrals in the finitely additive setting. We also give a
general version of the Fundamental Theorem of Prevision to deal with
conditional previsions and unbounded random variables.


title:
The Brownian cactus II. Upcrossings and local times of super-Brownian
  motion

abstract:
  We study properties of the random metric space called the Brownian map. For
every h>0, we consider the connected components of the complement of the open
ball of radius h centered at the root, and we let N(h,r) be the number of those
connected components that intersect the complement of the ball of radius h+r.
We then prove that r^3N(h,r) converges as r tends to 0 to a constant times the
density at h of the profile of distances from the root. In terms of the
Brownian cactus, this gives asymptotics for the number of vertices at height h
that have descendants at height h+r. Our proofs are based on a similar
approximation result for local times of super-Brownian motion by upcrossing
numbers. Our arguments make a heavy use of the Brownian snake and its special
Markov property.


title:
Accurate Evaluations of Strain and Stress in Atomistic Simulations of
  Crystalline Solids

abstract:
  In this paper, we study the accuracy of Irving-Kirkwood type of formulas for
the approximation of continuum quantities from atomistic simulations. Such
formulas are derived by expressing the displacement, deformation gradient and
stress in terms of certain kernel functions. We propose two criteria for
choosing the kernel functions to significantly improve the sampling accuracy.
We present a simple procedure to construct kernel functions that meet these
criteria. Further, numerical tests on homogeneous and non-homogeneous systems
provide validations for our analysis.


title: Evolution of the atomic and molecular gas content of galaxies

abstract:
  We study the evolution of atomic and molecular gas in galaxies in
semi-analytic models of galaxy formation that include new modeling of the
partitioning of cold gas in galactic discs into atomic, molecular, and ionised
phases. We adopt two scenarios for the formation of molecules: one
pressure-based and one metallicity-based. We find that both recipes
successfully reproduce the gas fractions and gas-to-stellar mass ratios of HI
and H2 in local galaxies,as well as the HI and H2 disc sizes up to z<2. We
reach good agreement with the locally observed HI and H2 mass function,
although both recipes slightly overpredict the low-mass end of the HI mass
function. Both of our models predict that the high-mass end of the HI mass
function remains nearly constant at redshifts z < 2.0. The metallicity-based
recipe yields a higher cosmic density of cold gas and much lower cosmic H2
fraction over the entire redshift range probed than the pressure based recipe.
These strong differences in HI mass function and cosmic density between the two
recipes are driven by low mass galaxies (log (M*/Msun) < 7) residing in low
mass halos (log (Mvir/Msun) < 10). Both recipes predict that galaxy gas
fractions remain high from z ~ 6-3 and drop rapidly at lower redshift. The
galaxy H2 fractions show a similar trend, but drop even more rapidly. We
provide predictions for the CO J = 1-0 luminosity of galaxies, which will be
directly comparable with observations with sub-mm and radio instruments.


title:
The blue sky of GJ3470b: the atmosphere of a low-mass planet unveiled by
  ground-based photometry

abstract:
  GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a
nearby M1.5 dwarf. It is of crucial interest for atmospheric studies because it
is one of the most inflated low-mass planets known, bridging the boundary
between "super-Earths" and Neptunian planets. We present two new ground-based
light curves of GJ3470b gathered by the LBC camera at the Large Binocular
Telescope. Simultaneous photometry in the ultraviolet (lambda_c = 357.5 nm) and
optical infrared (lambda_c = 963.5 nm) allowed us to detect a significant
change of the effective radius of GJ3470b as a function of wavelength. This can
be interpreted as a signature of scattering processes occurring in the
planetary atmosphere, which should be cloud-free and with a low mean molecular
weight. The unprecedented accuracy of our measurements demonstrates that the
photometric detection of Earth-sized planets around M dwarfs is achievable
using 8-10m size ground-based telescopes. We provide updated planetary
parameters, and a greatly improved orbital ephemeris for any forthcoming study
of this planet.


title: Atomic clocks: new prospects in metrology and geodesy

abstract:
  We present the latest developments in the field of atomic clocks and their
applications in metrology and fundamental physics. In the light of recent
advents in the accuracy of optical clocks, we present an introduction to the
relativistic modelization of frequency transfer and a detailed review of
chronometric geodesy.


title:
A Criterion for Deficient Numbers Using the Abundancy Index and
  Deficiency Functions

abstract:
  We show that $n$ is almost perfect if and only if $I(n) - 1 < D(n) \leq
I(n)$, where $I(n)$ is the abundancy index of $n$ and $D(n)$ is the deficiency
of $n$. This criterion is then extended to the case of integers $m$ satisfying
$D(m)>1$.


title: Content and popularity analysis of Tor hidden services

abstract:
  Tor hidden services allow running Internet services while protecting the
location of the servers. Their main purpose is to enable freedom of speech even
in situations in which powerful adversaries try to suppress it. However,
providing location privacy and client anonymity also makes Tor hidden services
an attractive platform for every kind of imaginable shady service. The ease
with which Tor hidden services can be set up has spurred a huge growth of
anonymously provided Internet services of both types. In this paper we analyse
the landscape of Tor hidden services. We have studied Tor hidden services after
collecting 39824 hidden service descriptors on 4th of Feb 2013 by exploiting
protocol and implementation flaws in Tor: we scanned them for open ports; in
the case of HTTP services, we analysed and classified their content. We also
estimated the popularity of hidden services by looking at the request rate for
hidden service descriptors by clients. We found that while the content of Tor
hidden services is rather varied, the most popular hidden services are related
to botnets.


title: Parity violation in the CMB bispectrum by a rolling pseudoscalar

abstract:
  We investigate parity-violating signatures of temperature and polarization
bispectra of the cosmic microwave background (CMB) in an inflationary model
where a rolling pseudoscalar produces large equilateral tensor non-Gaussianity.
By a concrete computation based on full-sky formalism, it is shown that
resultant CMB bispectra have nonzero signals in both parity-even $(\ell_1 +
\ell_2 + \ell_3 = {\rm even})$ and parity-odd $(\ell_1 + \ell_2 + \ell_3 = {\rm
odd})$ spaces, and are almost uncorrelated with usual scalar-mode equilateral
bispectra. These characteristic signatures and polarization information help to
detect such tensor non-Gaussianity. Use of both temperature and E-mode
bispectra potentially improves of $400\%$ the detectability with respect to an
analysis with temperature bispectrum alone. Considering B-mode bispectrum, the
signal-to-noise ratio may be able to increase by 3 orders of magnitude. We
present the $1\sigma$ uncertainties of a parameter depending on a coupling
constant and a rolling condition for the pseudoscalar expected in the ${\it
Planck}$ and the proposed PRISM experiments.


title: A Lie-Rinehart algebra with no antipode

abstract:
  The aim of this note is to communicate a simple example of a Lie-Rinehart
algebra whose enveloping algebra is not a Hopf algebroid in the sense of Boehm
and Szlachanyi.


title: Nucleon-nucleon scattering matrix and its Nc scaling

abstract:
  This paper focuses on the scaling of the S-matrix for elastic nucleon-nucleon
scattering at large Nc. It is argued that the logarithm of a typical S-matrix
element is proportional to Nc in the regime where the large Nc limit is taken
with momentum of the incident nucleons proportional Nc. The suggested scaling
was previously derived within the framework of potential scattering models for
purely elastic scattering in which the parameters scale the same way as in
large Nc QCD. A variety of heuristic arguments strongly suggest that the same
scaling holds in the realistic case where both elastic and inelastic scattering
are possible.


title: Dual Fibonacci Quaternions

abstract:
  In this study, we define the dual Fibonacci quaternion and the dual Lucas
quternion. We derive the relations between the dual Fibonacci and the dual
Lucas quaternion which connected the Fibonacci and the Lucas numbers.
Furthermore, we give the Binet and Cassini formulas for these quaternions.


title:
Quantum field theory on curved spacetime and the standard cosmological
  model

abstract:
  The aim of this review is to outline a full route from the fundamental
principles of algebraic quantum field theory on curved spacetime in its
present-day form to explicit phenomenological applications which allow for
comparison with experimental data. We give a brief account on the quantization
of the free scalar field and its Wick powers in terms of an algebra of
functionals on configuration space. Afterwards we demonstrate that there exist
states on this algebra in which the energy momentum tensor is qualitatively and
quantitatively of the perfect fluid form assumed in the standard model of
cosmology up to small corrections. We indicate the potential relevance of one
of these corrections for the actively debated phenomenon of Dark Radiation.


title:
Separable Approximations and Decomposition Methods for the Augmented
  Lagrangian

abstract:
  In this paper we study decomposition methods based on separable
approximations for minimizing the augmented Lagrangian. In particular, we study
and compare the Diagonal Quadratic Approximation Method (DQAM) of Mulvey and
Ruszczy\'{n}ski and the Parallel Coordinate Descent Method (PCDM) of
Richt\'arik and Tak\'a\v{c}. We show that the two methods are equivalent for
feasibility problems up to the selection of a single step-size parameter.
Furthermore, we prove an improved complexity bound for PCDM under strong
convexity, and show that this bound is at least $8(L'/\bar{L})(\omega-1)^2$
times better than the best known bound for DQAM, where $\omega$ is the degree
of partial separability and $L'$ and $\bar{L}$ are the maximum and average of
the block Lipschitz constants of the gradient of the quadratic penalty
appearing in the augmented Lagrangian.


title: Discrepancy and numerical integration on metric measure spaces

abstract:
  We study here the error of numerical integration on metric measure spaces
adapted to a decomposition of the space into disjoint subsets. We consider both
the error for a single given function, and the worst case error for all
functions in a given class of potentials. The main tools are the classical
Marcinkiewicz-Zygmund inequality and ad hoc definitions of function spaces on
metric measure spaces. The same techniques are used to prove the existence of
point distributions in metric measure spaces with small $L^p$ discrepancy with
respect to certain classes of subsets, for example metric balls.


title: Piecewise-linear pseudodiagrams

abstract:
  There are 2^n possible resolutions of a smooth pseudodiagram with n
precrossings. If we consider piecewise-linear (PL) pseudodiagrams and
resolutions that themselves are PL, certain resolutions of the pseudodiagram
may not exist in three-space. We investigate this situation and its impact on
the weighted resolution set of PL pseudodiagrams as well as introduce a concept
specific to PL pseudodiagrams, the forcing number. Our main result classifies
the PL shadows whose weighted resolution sets differ from the weighted
resolution set that would exist in the smooth case.


title: Magnetic fields of Herbig Ae/Be stars

abstract:
  We report on the status of our spectropolarimetric studies of Herbig Ae/Be
stars carried out during the last years. The magnetic field geometries of these
stars, investigated with spectropolarimetric time series, can likely be
described by centred dipoles with polar magnetic field strengths of several
hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields
have recently been observed with X-shooter in the visible and the near-IR, as
well as with the high-resolution near-IR spectrograph CRIRES. These
observations are of great importance to understand the relation between the
magnetic field topology and the physics of the accretion flow and the accretion
disk gas emission.


title:
Using ILP/SAT to determine pathwidth, visibility representations, and
  other grid-based graph drawings

abstract:
  We present a simple and versatile formulation of grid-based graph
representation problems as an integer linear program (ILP) and a corresponding
SAT instance. In a grid-based representation vertices and edges correspond to
axis-parallel boxes on an underlying integer grid; boxes can be further
constrained in their shapes and interactions by additional problem-specific
constraints. We describe a general d-dimensional model for grid representation
problems. This model can be used to solve a variety of NP-hard graph problems,
including pathwidth, bandwidth, optimum st-orientation, area-minimal (bar-k)
visibility representation, boxicity-k graphs and others. We implemented
SAT-models for all of the above problems and evaluated them on the Rome graphs
collection. The experiments show that our model successfully solves NP-hard
problems within few minutes on small to medium-size Rome graphs.


title:
Effects of a charged Higgs boson in $B \rightarrow D^{(*)} \tau \nu$
  decays

abstract:
  In this talk I consider the current status of $B \rightarrow D^{(*)} \tau
\nu$ decays in the context of two-Higgs-doublet models. The BaBar collaboration
has reported an excess in semileptonic $b \rightarrow c \tau \nu$ transitions
that has gathered recent interest as a possible signature of new physics. The
sensitivity of these decays to tree-level charged Higgs boson contributions is
discussed, taking into account the constraints from other semileptonic and
leptonic meson decays in which the charged Higgs would enter at the same level.


title: Approximate Bayesian Model Selection with the Deviance Statistic

abstract:
  Bayesian model selection poses two main challenges: the specification of
parameter priors for all models, and the computation of the resulting Bayes
factors between models. There is now a large literature on automatic and
objective parameter priors in the linear model. One important class are
$g$-priors, which were recently extended from linear to generalized linear
models (GLMs). We show that the resulting Bayes factors can be approximated by
test-based Bayes factors (Johnson [Scand. J. Stat. 35 (2008) 354-368]) using
the deviance statistics of the models. To estimate the hyperparameter $g$, we
propose empirical and fully Bayes approaches and link the former to minimum
Bayes factors and shrinkage estimates from the literature. Furthermore, we
describe how to approximate the corresponding posterior distribution of the
regression coefficients based on the standard GLM output. We illustrate the
approach with the development of a clinical prediction model for 30-day
survival in the GUSTO-I trial using logistic regression.


title: Connecting toric manifolds by conical Kahler-Einstein metrics

abstract:
  We give criterions for the existence of toric conical Kahler-Einstein and
Kahler-Ricci soliton metrics on any toric manifold in relation to the greatest
Ricci and Bakry-Emery-Ricci lower bound. We also show that any two toric
manifolds with the same dimension can be joined by a continuous path of toric
manifolds with conical Kahler-Einstein metrics in the Gromov-Hausdorff
topology.


title: Graphene Nanotechnology for the Next Generation Nonvolatile Memory

abstract:
  As conventional silicon technology is approaching its fundamental material
and physical limits with continuous scaling, there is a growing push to look
for new platform to design memory circuits for nanoelectronic applications. In
this paper we explore new design concept of nonvolatile memory based on
graphene nanotechnology. The investigation focuses on two forms of graphene
based field effect transistor (FET) carbon nanotube FET (CNTFET) and graphene
nanoribbon FET (GNRFET). The analysis reveals that GNRFET with a high trapping
capable oxide layer is suitable for ultra high ensity nonvolatile memory.


title: Bipartite entanglement of quantum states in a pair basis

abstract:
  The unambiguous detection and quantification of entanglement is a hot topic
of scientific research, though it is limited to low dimensions or specific
classes of states. Here we identify an additional class of quantum states, for
which bipartite entanglement measures can be efficiently computed, providing
new rigorous results. Such states are written in arbitrary $d\times d$
dimensions, where each basis state in the subsystem A is paired with only one
state in B. This new class, that we refer to as pair basis states, is
remarkably relevant in many physical situations, including quantum optics. We
find that negativity is a necessary and sufficient measure of entanglement for
mixtures of states written in the same pair basis. We also provide analytical
expressions for a tight lower-bound estimation of the entanglement of
formation, a central quantity in quantum information.

categories: quant-ph cond-mat.quant-gas cs.IT math.IT


title:
The Hot and Energetic Universe: The X-ray Integral Field Unit (X-IFU)
  for Athena+

abstract:
  The Athena+ mission concept is designed to implement the Hot and Energetic
Universe science theme submitted to the European Space Agency in response to
the call for White Papers for the definition of the L2 and L3 missions of its
science program. The Athena+ science payload consists of a large aperture high
angular resolution X-ray optics and twelve meters away, two interchangeable
focal plane instruments: the X-ray Integral Field Unit (X-IFU) and the Wide
Field Imager (WFI). The X-IFU is a cryogenic X-ray spectrometer, based on a
large array of Transition Edge Sensors (TES), offering 2.5 eV spectral
resolution, with ~5" pixels, over a field of view of 5 arc minutes in diameter.
In this paper, we briefly describe the Athena+ mission concept and the X-IFU
performance requirements. We then present the X-IFU detector and readout
electronics principles, the current design of the focal plane assembly, the
cooling chain and review the global architecture design. Finally, we describe
the current performance estimates, in terms of effective area, particle
background rejection, count rate capability and velocity measurements. Finally,
we emphasize on the latest technology developments concerning TES array
fabrication, spectral resolution and readout performance achieved to show that
significant progresses are being accomplished towards the demanding X-IFU
requirements.


title: The Hot and Energetic Universe: The Wide Field Imager (WFI) for Athena+

abstract:
  The Wide Field Imager (WFI) is one of the two scientific instruments proposed
for the Athena+ X-ray observatory. It will provide imaging in the 0.1-15 keV
band over a wide field, simultaneously with spectrally and time-resolved photon
counting. The instrument is designed to make optimal use of the grasp
(collecting area times solid angle product) provided by the optical design of
the Athena+ mirror system (Willingale et al. 2013), by combining a sensitive
approx. 40' diameter field of view (baseline; 50' goal) DEPFET detector with a
pixel size properly sampling the angular resolution of 5 arc sec on-axis (half
energy width).This synthesis makes the WFI a very powerful survey instrument,
significantly surpassing currently existing capabilities (Nandra et al. 2013;
Aird et al. 2013). In addition, the WFI will provide unprecedented simultaneous
high-time resolution and high count rate capabilities for the observation of
bright sources with low pile-up and high efficiency. In this paper, we
summarize the instrument design, the status of the technology development, and
the baseline performance.


title: Helices in the wake of precipitation fronts

abstract:
  A theoretical study of the emergence of helices in the wake of precipitation
fronts is presented. The precipitation dynamics is described by the
Cahn-Hilliard equation and the fronts are obtained by quenching the system into
a linearly unstable state. Confining the process onto the surface of a cylinder
and using the pulled-front formalism, our analytical calculations show that
there are front solutions that propagate into the unstable state and leave
behind a helical structure. We find that helical patterns emerge only if the
radius of the cylinder R is larger than a critical value R>R_c, in agreement
with recent experiments.


title:
Tunable add-drop filter using an active whispering gallery mode
  microcavity

abstract:
  An add-drop filter (ADF) fabricated using a whispering gallery mode resonator
has different crosstalks for add and drop functions due to non-zero intrinsic
losses of the resonator. Here, we show that introducing gain medium in the
resonator and optically pumping it below the lasing threshold not only allows
loss compensation to achieve similar and lower crosstalks but also tunability
in bandwidth and add-drop efficiency. For an active ADF fabricated using an
erbium-ytterbium co-doped microsphere, we achieved 24-fold enhancement in the
intrinsic quality factor, 3.5-fold increase in drop efficiency, bandwidth
tunability of 35 MHz and a crosstalk of only 2%.


title: Donagi-Markman cubic for the generalised Hitchin system

abstract:
  Donagi and Markman (1993) have shown that the infinitesimal period map for an
algebraic completely integrable Hamiltonian system is encoded in a section of
the third symmetric power of the cotangent bundle to the base of the system.
For the ordinary Hitchin system the cubic is given by a formula of Balduzzi and
Pantev. We prove that the Balduzzi--Pantev formula holds along maximal rank
symplectic leaves of the G-generalised Hitchin system.


title: Is charged lepton flavour violation a high energy phenomenon?

abstract:
  Searches for rare processes such as mu --> e gamma put stringent limits on
lepton flavour violation expected in many Beyond the Standard Model physics
scenarios. This usually precludes the observation of flavour violation at high
energy colliders such as the LHC. We here discuss a scenario where right-handed
neutrinos are produced via a Z' portal but which can only decay via small
flavour violating couplings. Consequently, the process rate is unsuppressed by
the small couplings and can be visible despite unobservably small mu --> e
gamma rates.


title: Moving curve ideals of rational plane parametrizations

abstract:
  In the nineties, several methods for dealing in a more efficient way with the
implicitization of rational parametrizations were explored in the Computer
Aided Geometric Design Community. The analysis of the validity of these
techniques has been a fruitful ground for Commutative Algebraists and Algebraic
Geometers, and several results have been obtained so far. Yet, a lot of
research is still being done currently around this topic. In this note we
present these methods, show their mathematical formulation, and survey current
results and open questions.


title: Deterministic bootstrap percolation in high dimensional grids

abstract:
  In this paper, we study the k-neighbor bootstrap percolation process on the
d-dimensional grid [n]^d, and show that the minimum number of initial vertices
that percolate is (1-d/k)n^d + O(n^{d-1})$ when d<=k<=2d. This confirms a
conjecture of Pete.


title: Global actions, K-theory and unimodular rows

abstract:
  Global actions were introduced by Bak in order to have a homotopy theory in a
purely algebraic setting. In this paper we apply his techniques in a particular
case: the (single domain) unimodular row global action. More precisely, we
compute the the path connected component and fundamental group for the
unimodular row global action. An explicit computation of the fundamental group
of the (connected component of) unimodular row global action is closely related
to stability questions in K-theory. This will be shown by constructing an exact
sequence with the fundamental group functor as the middle term and having
surjective stability for the functor K_2 on the left and injective stability
for the functor K_1 on the right.


title:
Establishing Conservation Laws in Pair Correlated Many Body theories: T
  matrix Approaches

abstract:
  We address conservation laws associated with current, momentum and energy and
show how they can be satisfied within many body theories which focus on pair
correlations. Of interest are two well known t-matrix theories which represent
many body theories which incorporate pairing in the normal state. The first of
these is associated with Nozieres Schmitt-Rink theory, while the second
involves the t-matrix of a BCS-Leggett like state as identified by Kadanoff and
Martin. T-matrix theories begin with an ansatz for the single particle self
energy and are to be distinguished from $\Phi$-derivable theories which
introduce an ansatz for a particular contribution to the thermodynamical
potential. Conservation laws are equivalent to Ward identities which we address
in some detail here. Although $\Phi$-derivable theories are often referred to
as "conserving theories", a consequence of this work is the demonstration that
these two t-matrix approaches similarly can be made to obey all conservation
laws. Moreover, simplifying approximations in $\Phi$-derivable theories,
frequently lead to results which are incompatible with conservation.


title:
On the gas dependence of thermal transpiration and a critical appraisal
  of correction methods for capacitive diaphragm gauges

abstract:
  Thermal transpiration effects are commonly encountered in low pressure
measurements with capacitance diaphragm gauges. They arise from the temperature
difference between the measurement volume and the temperature stabilised
manometer. Several approaches have been proposed to correct for the pressure
difference, but surface and geometric effects usually require that the
correction is determined for each gas type and gauge individually. Common
(semi) empirical corrections are based on studies of atoms or small molecules.
We present a simple calibration method for diaphragm gauges and compare
transpiration corrections for argon and styrene at pressures above 1 Pa. We
find that characteristic pressures at which the pressure difference reaches
half its maximum value, are compatible with the universal scaling p_{1/2} = 2
\{\eta} \cdot \{v_{th}} / d, thus essentially depending on gas viscosity \eta,
thermal molecular speed v_{th} and gauge tubing diameter d. This contradicts
current recommendations based on the Takaishi and Sensui formula, which show an
unphysical scaling with molecular size. Our results support the Miller or
\v{S}etina equations where the pressure dependency is basically determined by
the Knudsen number. The use of these two schemes is therefore recommended,
especially when thermal transpiration has to be predicted for new molecules.
Implications for investigations on large polyatomics are discussed.


title:
{\it K}-Shell Photoionization of Be-like and Li-like Ions of Atomic
  Nitrogen: Experiment and Theory

abstract:
  Absolute cross sections for the {\it K}-shell photoionization of Be-like and
Li-like atomic nitrogen ions were measured by employing the ion-photon
merged-beam technique at the SOLEIL synchrotron radiation facility in
Saint-Aubin, France. High-resolution spectroscopy at nominal resolutions of 38
meV, 56 meV, 111 meV, 133 meV FWHM for Be-like and 125 meV FWHM for Li-like
atomic nitrogen ions was achieved for the photon energies ranging from 410 eV
up to 460 eV. The experimental measurements are compared with theoretical
estimates from the multi-configuration Dirac-Fock (MCDF), R-matrix and an
empirical method. The interplay between experiment and theory enabled the
identification and characterisation of the strong 1s $\rightarrow$ 2p
resonances features observed in the {\it K}-shell spectra of each ion and the
region around 460 eV for the 1s $\rightarrow$ 3p resonance of the N$^{3+}$ ion
yielding suitable agreement with experiment.


title: Reduced and non-reduced linear spaces: Lines and points

abstract:
  In this paper we consider the problem of determining the Hilbert function of
schemes X of the proiective space P^n which are the generic union of s lines
and one m-multiple point. We completely solve this problem for any s and m when
n > 3. When n=3 we find several defective such schemes and conjecture that they
are the only ones. We verify this conjecture in several cases.


title: Online Ranking: Discrete Choice, Spearman Correlation and Other Feedback

abstract:
  Given a set $V$ of $n$ objects, an online ranking system outputs at each time
step a full ranking of the set, observes a feedback of some form and suffers a
loss. We study the setting in which the (adversarial) feedback is an element in
$V$, and the loss is the position (0th, 1st, 2nd...) of the item in the
outputted ranking. More generally, we study a setting in which the feedback is
a subset $U$ of at most $k$ elements in $V$, and the loss is the sum of the
positions of those elements.
  We present an algorithm of expected regret $O(n^{3/2}\sqrt{Tk})$ over a time
horizon of $T$ steps with respect to the best single ranking in hindsight. This
improves previous algorithms and analyses either by a factor of either
$\Omega(\sqrt{k})$, a factor of $\Omega(\sqrt{\log n})$ or by improving running
time from quadratic to $O(n\log n)$ per round. We also prove a matching lower
bound. Our techniques also imply an improved regret bound for online rank
aggregation over the Spearman correlation measure, and to other more complex
ranking loss functions.


title:
From Nodeless Clouds and Vortices to Gray Rings and Symmetry-Broken
  States in Two-Dimensional Polariton Condensates

abstract:
  We consider the existence, stability and dynamics of the nodeless state and
fundamental nonlinear excitations, such as vortices, for a
quasi-two-dimensional polariton condensate in the presence of pumping and
nonlinear damping. We find a series of interesting features that can be
directly contrastedto the case of the typically energy-conserving ultracold
alkali-atom Bose-Einstein condensates (BECs). For sizeable parameter ranges, in
line with earlier findings, the nodeless state becomes unstable towards the
formation of {\em stable} nonlinear single or multi-vortex excitations. The
potential instability of the single vortex is also examined and is found to
possess similar characteristics to those of the nodeless cloud. We also report
that, contrary to what is known, e.g., for the atomic BEC case, {\it stable}
stationary gray rings (that can be thought of as radial forms of a Nozaki-Bekki
hole) can be found for polariton condensates in suitable parametric regimes. In
other regimes, however, these may also suffer symmetry breaking instabilities.
The dynamical, pattern-forming implications of the above instabilities are
explored through direct numerical simulations and, in turn, give rise to
waveforms with triangular or quadrupolar symmetry.


title: Beyond Effective Field Theory for Dark Matter Searches at the LHC

abstract:
  We study the validity of effective field theory (EFT) interpretations of
monojet searches for dark matter at the LHC for vector and axial-vector
interactions. We show that the EFT approach is valid when the mediator has mass
m_med greater than 2.5 TeV. We find that the current limits on the contact
interaction scale Lambda in the EFT apply to theories that are perturbative for
dark matter mass m_DM < 800 GeV. However, for all values of m_DM in these
theories, the mediator width is larger than the mass, so that a particle-like
interpretation of the mediator is doubtful. Furthermore, consistency with the
thermal relic density occurs only for 170 <m_DM < 520 GeV. For lighter mediator
masses, the EFT limit either under-estimates the true limit (because the
process is resonantly enhanced) or over-estimates it (because the missing
energy distribution is too soft). We give some `rules of thumb' that can be
used to estimate the limit on Lambda (to an accuracy of about 50%) for any dark
matter and mediator masses from knowledge of the EFT limit. We also compare the
relative sensitivities of monojet and dark matter direct detection searches
finding that both dominate in different regions of the m_DM-m_med plane.
Comparing only the EFT limit with direct searches is misleading and can lead to
incorrect conclusions about the relative sensitivity of the two search
approaches.


title:
Dressed quantum graphs with optical nonlinearities approaching the
  fundamental limit

abstract:
  We dress bare quantum graphs with finite delta function potentials and
calculate optical nonlinearities that are found to match the fundamental limits
set by potential optimization. We show that structures whose first
hyperpolarizability is near the maximum are well described by only three
states, the so-called three-level Ansatz, while structures with the largest
second hyperpolarizability require four states. We analyze a very large set of
configurations for graphs with quasi-quadratic energy spectra and show how they
exhibit better response than bare graphs through exquisite optimization of the
shape of the eigenfunctions enabled by the existence of the finite potentials.
We also discover an exception to the universal scaling properties of the
three-level model parameters and trace it to the observation that a greater
number of levels are required to satisfy the sum rules even when the
three-level Ansatz is satisfied and the first hyperpolarizability is at its
maximum value, as specified by potential optimization. This exception in the
universal scaling properties of nonlinear optical structures at the limit is
traced to the discontinuity in the gradient of the eigenfunctions at the
location of the delta potential. This is the first time that dressed quantum
graphs have been devised and solved for their nonlinear response, and it is the
first analytical model of a confined dynamic system with a simple potential
energy that achieves the fundamental limits.


title: Many-to-One Boundary Labeling with Backbones

abstract:
  In this paper we study \emph{many-to-one boundary labeling with backbone
leaders}. In this new many-to-one model, a horizontal backbone reaches out of
each label into the feature-enclosing rectangle. Feature points that need to be
connected to this label are linked via vertical line segments to the backbone.
We present dynamic programming algorithms for label number and total leader
length minimization of crossing-free backbone labelings. When crossings are
allowed, we aim to obtain solutions with the minimum number of crossings. This
can be achieved efficiently in the case of fixed label order, however, in the
case of flexible label order we show that minimizing the number of leader
crossings is NP-hard.


title: Partial Gauge Fixing and Equivariant Cohomology

abstract:
  Given a gauge theory with gauge group G, it is sometimes useful to find an
equivalent formulation in terms of a non-trivial gauge subgroup H of G. This
amounts to fixing the gauge partially from G down to H. We study this problem
systematically, both from the algebraic and the path integral points of view.
We find that the usual BRST cohomology must be replaced by an equivariant
version and that the ghost Lagrangian must always include quartic ghost terms,
even at tree level. Both the Cartan and Weil models for equivariant cohomology
play a role and find natural interpretations within the physics framework.
Applications include the construction of D-brane models of emergent space, the
't Hooft's Abelian projection scenario in quantum chromodynamics and the
formulation of the low energy effective theories of grand unified models.


title:
Asymptotics of Chebyshev-Stirling and Stirling numbers of the second
  kind

abstract:
  For the Chebyshev-Stirling numbers, a special case of the Jacobi-Stirling
numbers, asymptotic formulae are derived in terms of a local central limit
theorem. The underlying probabilistic approach also applies to the classical
Stirling numbers of the second kind. Thereby a supplement of the asymptotic
analysis for these numbers is established.


title:
A Low-Dimensional Representation for Robust Partial Isometric
  Correspondences Computation

abstract:
  Intrinsic isometric shape matching has become the standard approach for pose
invariant correspondence estimation among deformable shapes. Most existing
approaches assume global consistency, i.e., the metric structure of the whole
manifold must not change significantly. While global isometric matching is well
understood, only a few heuristic solutions are known for partial matching.
Partial matching is particularly important for robustness to topological noise
(incomplete data and contacts), which is a common problem in real-world 3D
scanner data. In this paper, we introduce a new approach to partial, intrinsic
isometric matching. Our method is based on the observation that isometries are
fully determined by purely local information: a map of a single point and its
tangent space fixes an isometry for both global and the partial maps. From this
idea, we develop a new representation for partial isometric maps based on
equivalence classes of correspondences between pairs of points and their
tangent spaces. From this, we derive a local propagation algorithm that find
such mappings efficiently. In contrast to previous heuristics based on RANSAC
or expectation maximization, our method is based on a simple and sound
theoretical model and fully deterministic. We apply our approach to register
partial point clouds and compare it to the state-of-the-art methods, where we
obtain significant improvements over global methods for real-world data and
stronger guarantees than previous heuristic partial matching algorithms.


title: Twins:Device-free Object Tracking using Passive Tags

abstract:
  Without requiring objects to carry any transceiver, device-free based object
tracking provides a promising solution for many localization and tracking
systems to monitor non-cooperative objects such as intruders. However, existing
device-free solutions mainly use sensors and active RFID tags, which are much
more expensive compared to passive tags. In this paper, we propose a novel
motion detection and tracking method using passive RFID tags, named Twins. The
method leverages a newly observed phenomenon called critical state caused by
interference among passive tags. We contribute to both theory and practice of
such phenomenon by presenting a new interference model that perfectly explains
this phenomenon and using extensive experiments to validate it. We design a
practical Twins based intrusion detection scheme and implement a real prototype
with commercial off-the-shelf reader and tags. The results show that Twins is
effective in detecting the moving object, with low location error of 0.75m in
average.


title:
Mechanical and microscopic properties of the reversible plastic regime
  in a 2D jammed material

abstract:
  At the microscopic level, plastic flow of a jammed, disordered material
consists of a series of particle rearrangements that cannot be reversed by
subsequent deformation. An infinitesimal deformation of the same material has
no rearrangements. Yet between these limits, there may be a self-organized
plastic regime with rearrangements, but with no net change upon reversing a
deformation. We measure the oscillatory response of a jammed interfacial
material, and directly observe rearrangements that couple to bulk stress and
dissipate energy, but do not always give rise to global irreversibility.


title:
Achieving the Optimal Steaming Capacity and Delay Using Random Regular
  Digraphs in P2P Networks

abstract:
  In earlier work, we showed that it is possible to achieve $O(\log N)$
streaming delay with high probability in a peer-to-peer network, where each
peer has as little as four neighbors, while achieving any arbitrary fraction of
the maximum possible streaming rate. However, the constant in the $O(log N)$
delay term becomes rather large as we get closer to the maximum streaming rate.
In this paper, we design an alternative pairing and chunk dissemination
algorithm that allows us to transmit at the maximum streaming rate while
ensuring that all, but a negligible fraction of the peers, receive the data
stream with $O(\log N)$ delay with high probability. The result is established
by examining the properties of graph formed by the union of two or more random
1-regular digraphs, i.e., directed graphs in which each node has an incoming
and an outgoing node degree both equal to one.


title:
Effect of Dedifferentiation on Time to Mutation Acquisition in Stem
  Cell-Driven Cancers

abstract:
  Accumulating evidence suggests that many tumors have a hierarchical
organization, with the bulk of the tumor composed of relatively differentiated
short-lived progenitor cells that are maintained by a small population of
undifferentiated long-lived cancer stem cells. It is unclear, however, whether
cancer stem cells originate from normal stem cells or from dedifferentiated
progenitor cells. To address this, we mathematically modeled the effect of
dedifferentiation on carcinogenesis. We considered a hybrid
stochastic-deterministic model of mutation accumulation in both stem cells and
progenitors, including dedifferentiation of progenitor cells to a stem
cell-like state. We performed exact computer simulations of the emergence of
tumor subpopulations with two mutations, and we derived semi-analytical
estimates for the waiting time distribution to fixation. Our results suggest
that dedifferentiation may play an important role in carcinogenesis, depending
on how stem cell homeostasis is maintained. If the stem cell population size is
held strictly constant (due to all divisions being asymmetric), we found that
dedifferentiation acts like a positive selective force in the stem cell
population and thus speeds carcinogenesis. If the stem cell population size is
allowed to vary stochastically with density-dependent reproduction rates
(allowing both symmetric and asymmetric divisions), we found that
dedifferentiation beyond a critical threshold leads to exponential growth of
the stem cell population. Thus, dedifferentiation may play a crucial role, the
common modeling assumption of constant stem cell population size may not be
adequate, and further progress in understanding carcinogenesis demands a more
detailed mechanistic understanding of stem cell homeostasis.


title:
Primal and Dual Approximation Algorithms for Convex Vector Optimization
  Problems

abstract:
  Two approximation algorithms for solving convex vector optimization problems
(CVOPs) are provided. Both algorithms solve the CVOP and its geometric dual
problem simultaneously. The first algorithm is an extension of Benson's outer
approximation algorithm, and the second one is a dual variant of it. Both
algorithms provide an inner as well as an outer approximation of the (upper and
lower) images. Only one scalar convex program has to be solved in each
iteration. We allow objective and constraint functions that are not necessarily
differentiable, allow solid pointed polyhedral ordering cones, and relate the
approximations to an appropriate \epsilon-solution concept. Numerical examples
are provided.


title:
Herding Cats - Modelling, simulation, testing, and data-mining for weak
  memory

abstract:
  We propose an axiomatic generic framework for modelling weak memory. We show
how to instantiate this framework for SC, TSO, C++ restricted to
release-acquire atomics, and Power. For Power, we compare our model to a
preceding operational model in which we found a flaw. To do so, we define an
operational model that we show equivalent to our axiomatic model.
  We also propose a model for ARM. Our testing on this architecture revealed a
behaviour later acknowledged as a bug by ARM, and more recently 33 additional
anomalies.
  We offer a new simulation tool, called herd, which allows the user to specify
the model of his choice in a concise way. Given a specification of a model, the
tool becomes a simulator for that model. The tool relies on an axiomatic
description; this choice allows us to outperform all previous simulation tools.
Additionally, we confirm that verification time is vastly improved, in the case
of bounded model-checking.
  Finally, we put our models in perspective, in the light of empirical data
obtained by analysing the C and C++ code of a Debian Linux distribution. We
present our new analysis tool, called mole, which explores a piece of code to
find the weak memory idioms that it uses.


title: Subadditivity of syzygies of Koszul algebras

abstract:
  Estimates are obtained for the degrees of minimal syzygies of quotient
algebras of polynomial rings. For a class that includes Koszul algebra in
almost all characteristics, these degrees are shown to increase by at most 2
from one syzygy module to the next one. Even slower growth is proved if, in
addition, the algebra satisfies Green and Lazarsfeld's condition N_q with q >
1.


title: A classification of nilpotent 3-BCI groups

abstract:
  Given a finite group $G$ and a subset $S\subseteq G,$ the bi-Cayley graph
$\bcay(G,S)$ is the graph whose vertex set is $G \times \{0,1\}$ and edge set
is $\{\{(x,0),(s x,1)\} : x \in G, s\in S \}$. A bi-Cayley graph $\bcay(G,S)$
is called a BCI-graph if for any bi-Cayley graph $\bcay(G,T),$ $\bcay(G,S)
\cong \bcay(G,T)$ implies that $T = g S^\alpha$ for some $g \in G$ and $\alpha
\in \aut(G)$. A group $G$ is called an $m$-BCI-group if all bi-Cayley graphs of
$G$ of valency at most $m$ are BCI-graphs.In this paper we prove that, a finite
nilpotent group is a 3-BCI-group if and only if it is in the form $U \times V,$
where $U$ is a homocyclic group of odd order, and $V$ is trivial or one of the
groups $\Z_{2^r},$ $\Z_2^r$ and $\Q_8$.


title: Asymptotic formulas for stacks and unimodal sequences

abstract:
  We study enumeration functions for unimodal sequences of positive integers,
where the size of a sequence is the sum of its terms. We survey known results
for a number of natural variants of unimodal sequences, including Auluck's
generalized Ferrer diagrams, Wright's stacks, and Andrews' convex compositions.
These results describe combinatorial properties, generating functions, and
asymptotic formulas for the enumeration functions. We also prove several new
asymptotic results that fill in the notable missing cases from the literature,
including an open problem in statistical mechanics due to Temperley.
Furthermore, we explain the combinatorial and asymptotic relationship between
partitions, Andrews' Frobenius symbols, and stacks with summits.


title: Extensions and their Minimizations on the Sierpinski Gasket

abstract:
  We study the extension problem on the Sierpinski Gasket ($SG$). In the first
part we consider minimizing the functional $\mathcal{E}_{\lambda}(f) =
\mathcal{E}(f,f) + \lambda \int f^2 d \mu$ with prescribed values at a finite
set of points where $\mathcal{E}$ denotes the energy (the analog of $\int
|\nabla f|^2$ in Euclidean space) and $\mu$ denotes the standard self-similiar
measure on $SG$. We explicitly construct the minimizer $f(x) = \sum_{i} c_i
G_{\lambda}(x_i, x)$ for some constants $c_i$, where $G_{\lambda}$ is the
resolvent for $\lambda \geq 0$. We minimize the energy over sets in $SG$ by
calculating the explicit quadratic form $\mathcal{E}(f)$ of the minimizer $f$.
We consider properties of this quadratic form for arbitrary sets and then
analyze some specific sets. One such set we consider is the bottom row of a
graph approximation of $SG$. We describe both the quadratic form and a
discretized form in terms of Haar functions which corresponds to the continuous
result established in a previous paper. In the second part, we study a similar
problem this time minimizing $\int_{SG} |\Delta f(x)|^2 d \mu (x)$ for general
measures. In both cases, by using standard methods we show the existence and
uniqueness to the minimization problem. We then study properties of the unique
minimizers.


title: $N$-point Virasoro Algebras and Their Modules of Densities

abstract:
  In this paper we introduce and study $n$-point Virasoro algebras,
$\tilde{\W_a}$, which are natural generalizations of the classical Virasoro
algebra and have as quotients multipoint genus zero Krichever-Novikov type
algebras. We determine necessary and sufficient conditions for the latter two
such Lie algebras to be isomorphic. Moreover we determine their automorphisms,
their derivation algebras, their universal central extensions, and some other
properties. The list of automorphism groups that occur is $C_n$, $D_n$, $A_4$,
$S_4$ and $A_5$. We also construct a large class of modules which we call
modules of densities, and determine necessary and sufficient conditions for
them to be irreducible.


title: Can you play a fair game of craps with a loaded pair of dice?

abstract:
  We study, in various special cases, total distributions on the product of a
finite collection of finite probability spaces and, in particular, the question
of when the probability distribution of each factor space is determined by the
total distribution.


title:
Determinantal point processes in the plane from products of random
  matrices

abstract:
  We show the density of eigenvalues for three classes of random matrix
ensembles is determinantal. First we derive the density of eigenvalues of
product of $k$ independent $n\times n$ matrices with i.i.d. complex Gaussian
entries with a few of matrices being inverted. In second example we calculate
the same for (compatible) product of rectangular matrices with i.i.d. Gaussian
entries and in last example we calculate for product of independent truncated
unitary random matrices. We derive exact expressions for limiting expected
empirical spectral distributions of above mentioned ensembles.


title:
Host Galaxy Spectra and Consequences for SN Typing From The SDSS SN
  Survey

abstract:
  We present the spectroscopy from 5254 galaxies that hosted supernovae (SNe)
or other transient events in the Sloan Digital Sky Survey II (SDSS-II).
Obtained during SDSS-I, SDSS-II, and the Baryon Oscillation Spectroscopic
Survey (BOSS), this sample represents the largest systematic, unbiased,
magnitude limited spectroscopic survey of supernova (SN) host galaxies. Using
the host galaxy redshifts, we test the impact of photometric SN classification
based on SDSS imaging data with and without using spectroscopic redshifts of
the host galaxies. Following our suggested scheme, there are a total of 1166
photometrically classified SNe Ia when using a flat redshift prior and 1126 SNe
Ia when the host spectroscopic redshift is assumed. For 1024 (87.8%) candidates
classified as likely SNe Ia without redshift information, we find that the
classification is unchanged when adding the host galaxy redshift. Using
photometry from SDSS imaging data and the host galaxy spectra, we also report
host galaxy properties for use in future nalysis of SN astrophysics. Finally,
we investigate the differences in the interpretation of the light curve
properties with and without knowledge of the redshift. When using the SALT2
light curve fitter, we find a 21% increase in the number of fits that converge
when using the spectroscopic redshift. Without host galaxy redshifts, we find
that SALT2 light curve fits are systematically biased towards lower photometric
redshift estimates and redder colors in the limit of low signal-to-noise data.
The general improvements in performance of the light curve fitter and the
increased diversity of the host galaxy sample highlights the importance of host
galaxy spectroscopy for current photometric SN surveys such as the Dark Energy
Survey and future surveys such as the Large Synoptic Survey Telescope.


title: The effect of softening on dynamical simulations of galaxies

abstract:
  Dynamical simulations are a fundamental tool for studying the secular
evolution of disc galaxies. Even at their maximum resolution, they still follow
a limited number of particles and typically resolve scales of the order of a
few tens of parsecs. Generally, the spatial resolution is defined by (some
multiple of) the softening length, whose value is set as a compromise between
the desired resolution and the need for limiting small-scale noise. Several
works have studied the question whether a softening scale fixed in space and
time provides a good enough modelling of an astrophysical system. Here we
address this question within the context of dynamical simulations and disc
instabilities. We first follow the evolution of a galaxy-like object in
isolation and then set up a simulation of an idealised merger event. Alongside
a run using the standard fixed-softening approach, we performed simulations
where the softening lengths were let to vary from particle to particle
according to the evolution of the local density field in space and time. Even
though during the most violent phases of the merging the fixed-softening
simulation tends to underestimate the resulting matter densities, as far as the
evolution of the disc component is concerned we found no significant
differences among the runs. We conclude that using an appropriate fixed
softening scale is a safe approach to the problem of modelling an N-body,
non-cosmological disc galaxy system.


title: Robusteness of discrete nonuniform dichotomic behavior

abstract:
  For nonautonomous linear difference equations in Banach spaces we show that a
very general type of dichotomic behavior persists under small enough additive
linear perturbations. By using a new approach, we obtain two general robustness
theorems that improve several results in the literature and also contain new
situations. In particular, unlike several existent results for particular
growth rates, we show that, up to a multiplicative constant, the dichotomic
behavior for the perturbed equation is the same as the one for the original
equation.


title:
Mellin transforms with only critical zeros: generalized Hermite
  functions

abstract:
  We consider the Mellin transforms of certain generalized Hermite functions
based upon certain generalized Hermite polynomials, characterized by a
parameter $\mu>-1/2$. We show that the transforms have polynomial factors whose
zeros lie all on the critical line. The polynomials with zeros only on the
critical line are identified in terms of certain $_2F_1(2)$ hypergeometric
functions, being certain scaled and shifted Meixner-Pollaczek polynomials.
Other results of special function theory are presented.


title: nuSTORM - Neutrinos from STORed Muons: Proposal to the Fermilab PAC

abstract:
  The nuSTORM facility has been designed to deliver beams of electron neutrinos
and muon neutrinos (and their anti-particles) from the decay of a stored muon
beam with a central momentum of 3.8 GeV/c and a momentum acceptance of 10%. The
facility is unique in that it will: 1. Allow searches for sterile neutrinos of
exquisite sensitivity to be carried out; 2. Serve future long- and
short-baseline neutrino-oscillation programs by providing definitive
measurements of electron neutrino and muon neutrino scattering cross sections
off nuclei with percent-level precision; and 3. Constitutes the crucial first
step in the development of muon accelerators as a powerful new technique for
particle physics. The document describes the facility in detail and
demonstrates its physics capabilities. This document was submitted to the
Fermilab Physics Advisory Committee in consideration for Stage I approval.


title:
A Hypergraph-Partitioned Vertex Programming Approach for Large-scale
  Consensus Optimization

abstract:
  In modern data science problems, techniques for extracting value from big
data require performing large-scale optimization over heterogenous, irregularly
structured data. Much of this data is best represented as multi-relational
graphs, making vertex programming abstractions such as those of Pregel and
GraphLab ideal fits for modern large-scale data analysis. In this paper, we
describe a vertex-programming implementation of a popular consensus
optimization technique known as the alternating direction of multipliers
(ADMM). ADMM consensus optimization allows elegant solution of complex
objectives such as inference in rich probabilistic models. We also introduce a
novel hypergraph partitioning technique that improves over state-of-the-art
partitioning techniques for vertex programming and significantly reduces the
communication cost by reducing the number of replicated nodes up to an order of
magnitude. We implemented our algorithm in GraphLab and measure scaling
performance on a variety of realistic bipartite graph distributions and a large
synthetic voter-opinion analysis application. In our experiments, we are able
to achieve a 50% improvement in runtime over the current state-of-the-art
GraphLab partitioning scheme.


title: Strict Confluent Drawing

abstract:
  We define strict confluent drawing, a form of confluent drawing in which the
existence of an edge is indicated by the presence of a smooth path through a
system of arcs and junctions (without crossings), and in which such a path, if
it exists, must be unique. We prove that it is NP-complete to determine whether
a given graph has a strict confluent drawing but polynomial to determine
whether it has an outerplanar strict confluent drawing with a fixed vertex
ordering (a drawing within a disk, with the vertices placed in a given order on
the boundary).


title: Enhancement of laser-driven electron acceleration in an ion channel

abstract:
  A long laser beam propagating through an underdense plasma produces a
positively charged ion channel by expelling plasma electrons in the transverse
direction. We consider the dynamics of a test electron in a resulting
two-dimensional channel under the action of the laser field and the transverse
electric field of the channel. A considerable enhancement of the axial momentum
can be achieved in this case via amplification of betatron oscillations. It is
shown that the oscillations can be parametrically amplified when the betatron
frequency, which increases with the wave amplitude, becomes comparable to the
frequency of its modulations. The modulations are caused by non-inertial
(accelerated/decelerated) relativistic axial motion induced by the wave
regardless of the angle between the laser electric field and the field of the
channel. We have performed a parameter scan for a wide range of wave amplitudes
and ion densities and we have found that, for a given density, there is a well
pronounced wave amplitude threshold above which the maximum electron energy is
considerably enhanced. We have also calculated a time-integrated electron
spectrum produced by an ensemble of electrons with a spread in the initial
transverse momentum. The numerical results show that the considerable energy
enhancement is accompanied by spectrum broadening. The presented mechanism of
energy enhancement is robust with respect to an axial increase of ion density,
because it relies on a threshold phenomenon rather than on a narrow linear
resonance.


title:
Sparse reconstructions of overlapping three-dimensional point spread
  functions using overcomplete dictionaries

abstract:
  When a single molecule is detected in a wide-field microscope, the image
approximates the point spread function of the system. However, as the
distribution of molecules becomes denser and their images begin to coincide,
existing solutions to determine the number of molecules present and their
precise three-dimensional locations can tolerate little to no overlap. A
solution to this problem involving matched optical and digital techniques, as
here proposed, is critical to increase the allowable labeling density and to
accelerate single-molecule localization microscopy.


title: Surfaces with parallel mean curvature in Sasakian space forms

abstract:
  We study the global geometry of surfaces in Sasakian space forms whose mean
curvature vector is parallel in the normal bundle (these include the Riemannian
Heisenberg space of dimension $2n+1$). We prove a codimension reduction
theorem. We introduce two holomorphic quadratic differentials on anti-invariant
such surfaces and use them to obtain classification theorems.


title: Soft asymptotics with mass gap

abstract:
  From the operator product expansion the gluon condensate controls a certain
power law correction to the ultraviolet behavior of the gauge theory. This is
reflected by the asymptotic behavior of the effective gluon mass function as
determined by its Schwinger-Dyson equation. We show that the current state of
the art determination of the gluon mass function by Binosi, Ibanez and
Papavassiliou points to a vanishing gluon condensate. If this is correct then
the vacuum energy also vanishes in massless QCD. This result can be interpreted
as a statement about a softness in the ultraviolet behavior and the consistency
of this behavior with a mass gap.


title:
Line Defects, Tropicalization, and Multi-Centered Quiver Quantum
  Mechanics

abstract:
  We study BPS line defects in N=2 supersymmetric four-dimensional field
theories. We focus on theories of "quiver type," those for which the BPS
particle spectrum can be computed using quiver quantum mechanics. For a wide
class of models, the renormalization group flow between defects defined in the
ultraviolet and in the infrared is bijective. Using this fact, we propose a way
to compute the BPS Hilbert space of a defect defined in the ultraviolet, using
only infrared data. In some cases our proposal reduces to studying
representations of a "framed" quiver, with one extra node representing the
defect. In general, though, it is different. As applications, we derive a
formula for the discontinuities in the defect renormalization group map under
variations of moduli, and show that the operator product algebra of line
defects contains distinguished subalgebras with universal multiplication rules.
We illustrate our results in several explicit examples.


title: The effects of psammophilous plants on sand dune dynamics

abstract:
  Psammophilous plants are special plants that flourish in sand moving
environments. There are two main mechanisms by which the wind affects these
plants: (i) sand drift exposes roots and covers branches--the exposed roots
turn into new plants and the covered branches turn into new roots; both
mechanisms result in an enhanced growth rate of the psammophilous plant cover
of the dunes; (ii) strong winds, often associated with sand movement, tear
branches and seed them in nearby locations, resulting in new plants and an
enhanced growth rate of the psammophilous plant cover of the dunes. Despite
their important role in dune dynamics, to our knowledge, psammophilous plants
have never been incorporated into mathematical models of sand dunes. Here, we
attempt to model the effects of these plants on sand dune dynamics. We
construct a set of three ordinary differential equations for the fractions of
surface cover of regular vegetation, biogenic soil crust and psammophilous
plants. The latter reach their optimal growth under (i) specific sand drift or
(ii) specific wind power. We show that psammophilous plants enrich the sand
dune dynamics. Depending on the climatological conditions, it is possible to
obtain one, two, or three steady dune states. The activity of the dunes can be
associated with the surface cover--bare dunes are active, and dunes with
significant cover of vegetation, biogenic soil crust, or psammophilous plants
are fixed. Our model shows that under suitable precipitation rates and wind
power, the dynamics of the different cover types is in accordance with the
common view that dunes are initially stabilized by psammophilous plants that
reduce sand activity, thus enhancing the growth of regular vegetation that
eventually dominates the cover of the dunes and determines their activity.


title:
Lattice construction of pseudopotential Hamiltonians for Fractional
  Chern Insulators

abstract:
  Fractional Chern insulators are new realizations of fractional quantum Hall
states in lattice systems without orbital magnetic field. These states can be
mapped onto conventional fractional quantum Hall states through the Wannier
state representation (Phys. Rev. Lett. 107, 126803 (2011)). In this paper, we
use the Wannier state representation to construct the pseudopotential
Hamiltonians for fractional Chern insulators, which are interaction
Hamiltonians with certain ideal model wavefunctions as exact ground states. We
show that these pseudopotential Hamiltonians can be approximated by
short-ranged interactions in fractional Chern insulators, and that their range
will be minimized by an optimal gauge choice for the Wannier states. As
illustrative examples, we explicitly write down the form of the lowest
pseudopotential for several fractional Chern insulator models including the
lattice Dirac model and the checkerboard model with Chern number 1, and the
d-wave model and the triangular lattice model with Chern number 2. The proposed
pseudopotential Hamiltonians have the 1/3 Laughlin state as their groundstate
when the Chern number C=1, and a topological nematic (330) state as their
groundstate when C=2. Also included are the results of an interpolation between
the d-wave model and two decoupled layers of lattice Dirac models, which
explicitly demonstrate the relation between C=2 fractional Chern insulators and
bilayer fractional quantum Hall states. The proposed states can be verified by
future numerical works, and in particular provide a model Hamiltonian for the
topological nematic states that have not been realized numerically.


title:
Measurement of the W gamma and Z gamma inclusive cross sections in pp
  collisions at sqrt(s) = 7 TeV and limits on anomalous triple gauge boson
  couplings

abstract:
  Measurements of W gamma and Z gamma production in proton-proton collisions at
sqrt(s) = 7 TeV are used to extract limits on anomalous triple gauge couplings.
The results are based on data recorded by the CMS experiment at the LHC that
correspond to an integrated luminosity of 5.0 inverse femtobarns. The cross
sections are measured for photon transverse momenta pt[gamma] > 15 GeV, and for
separations between photons and final-state charged leptons in the
pseudorapidity-azimuthal plane of Delta R[l, gamma] > 0.7 in l nu gamma and ll
gamma final states, where l refers either to an electron or a muon. A dilepton
invariant mass requirement of m[ll] > 50 GeV is imposed for the Z gamma
process. No deviations are observed relative to predictions from the standard
model, and limits are set on anomalous WW gamma, ZZ gamma, and Z gamma gamma
triple gauge couplings.


title:
Stability of Polynomial Differential Equations: Complexity and Converse
  Lyapunov Questions

abstract:
  We consider polynomial differential equations and make a number of
contributions to the questions of (i) complexity of deciding stability, (ii)
existence of polynomial Lyapunov functions, and (iii) existence of sum of
squares (sos) Lyapunov functions.
  (i) We show that deciding local or global asymptotic stability of cubic
vector fields is strongly NP-hard. Simple variations of our proof are shown to
imply strong NP-hardness of several other decision problems: testing local
attractivity of an equilibrium point, stability of an equilibrium point in the
sense of Lyapunov, invariance of the unit ball, boundedness of trajectories,
convergence of all trajectories in a ball to a given equilibrium point,
existence of a quadratic Lyapunov function, local collision avoidance, and
existence of a stabilizing control law.
  (ii) We present a simple, explicit example of a globally asymptotically
stable quadratic vector field on the plane which does not admit a polynomial
Lyapunov function (joint work with M. Krstic). For the subclass of homogeneous
vector fields, we conjecture that asymptotic stability implies existence of a
polynomial Lyapunov function, but show that the minimum degree of such a
Lyapunov function can be arbitrarily large even for vector fields in fixed
dimension and degree. For the same class of vector fields, we further establish
that there is no monotonicity in the degree of polynomial Lyapunov functions.
  (iii) We show via an explicit counterexample that if the degree of the
polynomial Lyapunov function is fixed, then sos programming may fail to find a
valid Lyapunov function even though one exists. On the other hand, if the
degree is allowed to increase, we prove that existence of a polynomial Lyapunov
function for a planar or a homogeneous vector field implies existence of a
polynomial Lyapunov function that is sos and that the negative of its
derivative is also sos.


title: A bilateral extension of the $q$-Selberg integral

abstract:
  A multi-dimensional bilateral $q$-series extending the $q$-Selberg integral
is studied using concepts of truncation, regularization and connection
formulae. Following Aomoto's method, which involves regarding the $q$-series as
a solution of a $q$-difference equation fixed by its asymptotic behavior, an
infinite product evaluation is obtained. The $q$-difference equation is derived
applying the shifted symmetric polynomials introduced by Knop and Sahi. As a
special case of the infinite product formula, Askey--Evans's $q$-Selberg
integral evaluation and its generalization by Tarasov--Varchenko and Stokman is
reclaimed, and an explanation in the context of Aomoto's setting is thus
provided.


title:
Necessary condition of divisibility by the power of prime ideal and its
  application to Fermat's problem

abstract:
  In the paper we use necessary condition for divisibility by the power of
prime ideal.


title: Concentration Inequalities for Bounded Random Vectors

abstract:
  We derive simple concentration inequalities for bounded random vectors, which
generalize Hoeffding's inequalities for bounded scalar random variables. As
applications, we apply the general results to multinomial and Dirichlet
distributions to obtain multivariate concentration inequalities.


title:
Surface Brightness Profiles of Dwarf Galaxies: I. Profiles and
  Statistics

abstract:
  Radial surface brightness profiles of spiral galaxies are classified into
three types: (I) single exponential, or the light falls off with one
exponential to a break before falling off (II) more steeply, or (III) less
steeply. Profile breaks are also found in dwarf disks, but some dwarf Type IIs
are flat or increasing out to a break before falling off. Here we re-examine
the stellar disk profiles of 141 dwarfs: 96 dwarf irregulars (dIms), 26 Blue
Compact Dwarfs (BCDs), and 19 Magellanic-type spirals (Sms). We fit single,
double, or even triple exponential profiles in up to 11 passbands: GALEX FUV
and NUV, ground-based UBV JHK and H{\alpha}, and Spitzer 3.6 and 4.5 {\mu}m. We
find that more luminous galaxies have brighter centers, larger inner and outer
scale lengths, and break at larger radii; dwarf trends with M_B extend to
spirals. However, the V-band break surface brightness is independent of break
type, M_B, and Hubble type. Dwarf Type II and III profiles fall off similarly
beyond the breaks but have different interiors and IIs break ~twice as far as
IIIs. Outer Type II and III scale lengths may have weak trends with wavelength,
but pure Type II inner scale lengths clearly decrease from the FUV to visible
bands whereas Type III inner scale lengths increase with redder bands. This
suggests the influence of different star formation histories on profile type,
but nonetheless the break location is approximately the same in all passbands.
Dwarfs continue trends between profile and Hubble types such that later-type
galaxies have more Type II but fewer Type I and III profiles than early-type
spirals. BCDs and Sms are over-represented as Types III and II, respectively,
compared to dIms.


title: Experimental verification of quantum computations

abstract:
  Quantum computers are expected to offer substantial speedups over their
classical counterparts and to solve problems that are intractable for classical
computers. Beyond such practical significance, the concept of quantum
computation opens up new fundamental questions, among them the issue whether or
not quantum computations can be certified by entities that are inherently
unable to compute the results themselves. Here we present the first
experimental verification of quantum computations. We show, in theory and in
experiment, how a verifier with minimal quantum resources can test a
significantly more powerful quantum computer. The new verification protocol
introduced in this work utilizes the framework of blind quantum computing and
is independent of the experimental quantum-computation platform used. In our
scheme, the verifier is only required to generate single qubits and transmit
them to the quantum computer. We experimentally demonstrate this protocol using
four photonic qubits and show how the verifier can test the computer's ability
to perform measurement-based quantum computations.


title: The planetary nebula population in the halo of M87

abstract:
  We investigate the diffuse light in the outer regions of the nearby
elliptical galaxy M87 in the Virgo cluster, using planetary nebulas (PNs) as
tracers. The surveyed areas (0.43 squared degrees) cover M87 up to a radial
distance of 150 kpc, in the ransition region between galaxy halo and
intracluster light (ICL). All PNs are identified through the on-off band
technique using automatic selection criteria based on the distribution of the
detected sources in the colour-magnitude diagram and the properties of their
point-spread function. We extract a catalogue of 688 objects down to
m_5007=28.4, with an estimated residual contamination from foreground stars and
background Lyalpha galaxies, which amounts to ~35% of the sample. This is one
of the largest extragalactic PN samples in number of candidates, magnitude
depth, and radial extent, which allows us to carry out an unprecedented
photometric study of the PN population in the outer regions of M87. We find
that the logarithmic density profile of the PN distribution is shallower than
the surface brightness profile at large radii. This behaviour is consistent
with the superposition of two components associated with the halo of M87 and
with the ICL, which have different luminosity specific PN numbers, the ICL
contributing three times more PNs per unit light. Because of the depth of this
survey we are also able to study the shape of the PN luminosity function (PNLF)
in the outer regions of M87. We find a slope for the PNLF that is steeper at
fainter magnitudes than the standard analytical PNLF formula and adopt a
generalised model that treats the slope as a free parameter. Comparing the PNLF
of M87 and the M31 bulge, both normalised by the sampled luminosity, the M87
PNLF contains fewer bright PNs and has a steeper slope towards fainter
magnitudes.


title: Baryogenesis from the Inflaton Field

abstract:
  In this letter we show that the inflaton can generate the cosmological baryon
asymmetry. We take the inflaton to be a complex scalar field with a weakly
broken global symmetry and develop a new variant on the Affleck-Dine mechanism.
The inflationary phase is driven by a quadratic potential whose amplitude of
B-modes is in agreement with BICEP2 data. We show that a conserved particle
number is produced in the latter stage of inflation, which can later decay to
baryons. We present promising embeddings in particle physics, including the use
of high dimension operators for decay or using a colored inflaton. We also
point out observational consequences, including a prediction of isocurvature
fluctuations, whose amplitude is just below current limits, and a possible
large scale dipole.


title:
Encoding the infrared excess (IRX) in the NUVrK color diagram for
  star-forming galaxies

abstract:
  We present an empirical method of assessing the star formation rate (SFR) of
star-forming galaxies based on their locations in the rest-frame color-color
diagram (NUV-r) vs (r-K). By using the Spitzer 24 micron sample in the COSMOS
field (~16400 galaxies with 0.2 < z < 1.3) and a local GALEX-SDSS-SWIRE sample
(~700 galaxies with z < 0.2), we show that the mean infrared excess <IRX>= <
L_IR / L_UV > can be described by a single vector, NRK, that combines the two
colors. The calibration between <IRX> and NRK allows us to recover the IR
luminosity, L_IR, with an accuracy of ~0.21 dex for the COSMOS sample and ~0.27
dex for the local one. The SFRs derived with this method agree with the ones
based on the observed (UV+IR) luminosities and on the spectral energy
distribution fitting for the vast majority (~85 %) of the star-forming
population. Thanks to a library of model galaxy SEDs with realistic
prescriptions for the star formation history, we show that we need to include a
two-component dust model (i.e., birth clouds and diffuse ISM) and a full
distribution of galaxy inclinations in order to reproduce the behavior of the
<IRX> stripes in the NUVrK diagram. In conclusion, the NRK method, based only
on rest-frame UV and optical colors available in most of the extragalactic
fields, offers a simple alternative of assessing the SFR of star-forming
galaxies in the absence of far-IR or spectral diagnostic observations.


title:
Habitable Planets Around White Dwarfs: an Alternate Mission for the
  Kepler Spacecraft

abstract:
  A large fraction of white dwarfs (WDs) may host planets in their habitable
zones. These planets may provide our best chance to detect bio-markers on a
transiting exoplanet, thanks to the diminished contrast ratio between the
Earth-sized WD and its Earth-sized planets. The JWST is capable of obtaining
the first spectroscopic measurements of such planets, yet there are no known
planets around WDs. Here we propose to take advantage of the unique capability
of the Kepler spacecraft in the 2-Wheels mode to perform a transit survey that
is capable of identifying the first planets in the habitable zone of a WD. We
propose to obtain Kepler time-series photometry of 10,000 WDs in the SDSS
imaging area to search for planets in the habitable zone. Thanks to the large
field of view of Kepler, for the first time in history, a large number of WDs
can be observed at the same time, which is essential for discovering transits.
Our proposed survey requires a total of 200 days of observing time, and will
find up to 100 planets in the WD habitable zone. This survey will maintain
Kepler's spirit of searching for habitable Earths, but near new hosts. With
few-day observations and minute-cadences per field, it will also open up a
completely unexplored discovery space. In addition to planets, this survey is
sensitive to pulsating WDs, as well as eclipsing short period stellar and
substellar companions. These have important implications for constraining the
double WD merger rate and their contribution to Type Ia supernovae and the
gravitational wave foreground. Given the relatively low number density of our
targets, this program can be combined with other projects that would benefit
from high cadence and many-fields observations with Kepler, e.g. a transit
survey of a magnitude-limited, complete sample of nearby M dwarfs or
asteroseismology of variable stars (e.g. RR Lyrae) in the same fields.


title: Generating the Observed Baryon Asymmetry from the Inflaton Field

abstract:
  We propose a mechanism by which the inflaton can generate baryogenesis, by
taking the inflaton to be a complex scalar field with a weakly broken global
symmetry and present a new version of the Affleck-Dine mechanism. The smallness
of the breaking is motivated both by technical naturalness and a requirement
for inflation. We study inflation driven by a quadratic potential for
simplicity and discuss generalizations to other potentials. We compute the
inflationary dynamics and find that a conserved particle number is obtained
towards the end of inflation. We then explain in detail the later decay to
baryons. We present two promising embeddings in particle physics: (i) using
high dimension operators for a gauge singlet; we find this leads to the
observed asymmetry for decay controlled by the ~ grand unified theory scale and
this is precisely the regime where the effective field theory applies. (ii)
using a colored inflaton, which requires small couplings. We also point out two
observational consequences: a possible large scale dipole in the baryon
density, and a striking prediction of isocurvature fluctuations whose amplitude
is found to be just below current limits and potentially detectable in future
data.


title:
Warm Jupiters Need Close "Friends" for High-Eccentricity Migration -- A
  Stringent Upper Limit on the Perturber's Separation

abstract:
  We propose a stringent observational test on the formation of warm Jupiters
(gas-giant planets with 10 d <~ P <~ 100 d) by high-eccentricity (high-e)
migration mechanisms. Unlike hot Jupiters, the majority of observed warm
Jupiters have pericenter distances too large to allow efficient tidal
dissipation to induce migration. To access the close pericenter required for
migration during a Kozai-Lidov cycle, they must be accompanied by a strong
enough perturber to overcome the precession caused by General Relativity (GR),
placing a strong upper limit on the perturber's separation. For a warm Jupiter
at a ~ 0.2 AU, a Jupiter-mass (solar-mass) perturber is required to be <~ 3 AU
(<~ 30 AU) and can be identified observationally. Among warm Jupiters detected
by Radial Velocities (RV), >~ 50% (5 out of 9) with large eccentricities (e >~
0.4) have known Jovian companions satisfying this necessary condition for
high-e migration. In contrast, <~ 20 % (3 out of 17) of the low-e (e <~ 0.2)
warm Jupiters have detected additional Jovian companions, suggesting that
high-e migration with planetary perturbers may not be the dominant formation
channel. Complete, long-term RV follow-ups of the warm-Jupiter population will
allow a firm upper limit to be put on the fraction of these planets formed by
high-e migration. Transiting warm Jupiters showing spin-orbit misalignments
will be interesting to apply our test. If the misalignments are solely due to
high-e migration as commonly suggested, we expect that the majority of warm
Jupiters with low-e (e <~0.2) are not misaligned, in contrast with low-e hot
Jupiters.