title:
A consistent operator splitting algorithm and a two-metric variant:
  Application to topology optimization

abstract:
  In this work, we explore the use of operator splitting algorithms for solving
regularized structural topology optimization problems. The context is the
classical structural design problems (e.g., compliance minimization and
compliant mechanism design), parameterized by means of density functions, whose
ill-posendess is addressed by introducing a Tikhonov regularization term. The
proposed forward-backward splitting algorithm treats the constituent terms of
the cost functional separately which allows suitable approximations of the
structural objective. We will show that one such approximation, inspired by the
optimality criteria algorithm and reciprocal expansions, improves the
convergence characteristics and leads to an update scheme that resembles the
well-known heuristic sensitivity filtering method. We also discuss a two-metric
variant of the splitting algorithm that removes the computational overhead
associated with bound constraints on the density field without compromising
convergence and quality of optimal solutions. We present several numerical
results and investigate the influence of various algorithmic parameters.


title: Large-scale Multi-label Learning with Missing Labels

abstract:
  The multi-label classification problem has generated significant interest in
recent years. However, existing approaches do not adequately address two key
challenges: (a) the ability to tackle problems with a large number (say
millions) of labels, and (b) the ability to handle data with missing labels. In
this paper, we directly address both these problems by studying the multi-label
problem in a generic empirical risk minimization (ERM) framework. Our
framework, despite being simple, is surprisingly able to encompass several
recent label-compression based methods which can be derived as special cases of
our method. To optimize the ERM problem, we develop techniques that exploit the
structure of specific loss functions - such as the squared loss function - to
offer efficient algorithms. We further show that our learning framework admits
formal excess risk bounds even in the presence of missing labels. Our risk
bounds are tight and demonstrate better generalization performance for low-rank
promoting trace-norm regularization when compared to (rank insensitive)
Frobenius norm regularization. Finally, we present extensive empirical results
on a variety of benchmark datasets and show that our methods perform
significantly better than existing label compression based methods and can
scale up to very large datasets such as the Wikipedia dataset.


title:
Automated Defect Localization via Low Rank Plus Outlier Modeling of
  Propagating Wavefield Data

abstract:
  This work proposes an agnostic inference strategy for material diagnostics,
conceived within the context of laser-based non-destructive evaluation methods,
which extract information about structural anomalies from the analysis of
acoustic wavefields measured on the structure's surface by means of a scanning
laser interferometer. The proposed approach couples spatiotemporal windowing
with low rank plus outlier modeling, to identify a priori unknown deviations in
the propagating wavefields caused by material inhomogeneities or defects, using
virtually no knowledge of the structural and material properties of the medium.
This characteristic makes the approach particularly suitable for diagnostics
scenarios where the mechanical and material models are complex, unknown, or
unreliable. We demonstrate our approach in a simulated environment using
benchmark point and line defect localization problems based on propagating
flexural waves in a thin plate.


title:
Evidence that Gamma-ray Burst 130702A Exploded in a Dwarf Satellite of a
  Massive Galaxy

abstract:
  GRB 130702A is a nearby long-duration gamma-ray burst (LGRB) discovered by
the Fermi satellite whose associated afterglow was detected by the Palomar
Transient Factory. Subsequent photometric and spectroscopic monitoring has
identified a coincident broad-lined Type Ic supernova (SN), and nebular
emission detected near the explosion site is consistent with a redshift of
z=0.145. The SN-GRB exploded at an offset of ~7.6" from the center of an
inclined r=18.1 mag red disk-dominated galaxy, and ~0.6" from the center of a
much fainter r=23 mag object. We obtained Keck-II DEIMOS spectra of the two
objects and find a 2{\sigma} upper limit on their line-of-sight velocity offset
of ~<60 km/s. If we project the SN-GRB coordinates onto the plane of the
inclined massive disk galaxy, the explosion would have a ~61+-10 kpc offset, or
~6 times the galaxy's half-light radius. This large estimated nuclear offset
suggests that the faint source is not a star-forming region of the massive red
galaxy but is instead a dwarf galaxy. The star-formation rate of the dwarf
galaxy is ~0.05 solar masses per year, and we place an upper limit on its
oxygen abundance of 12 + log(O/H) < 8.16 dex. The identification of an LGRB in
a dwarf satellite of a massive, metal-rich primary galaxy suggests that recent
detections of LGRBs spatially coincident with metal-rich galaxies may be, in
some cases, superpositions.


title:
Tunable symmetry breaking and helical edge transport in a graphene
  quantum spin Hall state

abstract:
  Low-dimensional electronic systems have traditionally been obtained by
electrostatically confining electrons, either in heterostructures or in
intrinsically nanoscale materials such as single molecules, nanowires, and
graphene. Recently, a new paradigm has emerged with the advent of
symmetry-protected surface states on the boundary of topological insulators,
enabling the creation of electronic systems with novel properties. For example,
time reversal symmetry (TRS) endows the massless charge carriers on the surface
of a three-dimensional topological insulator with helicity, locking the
orientation of their spin relative to their momentum. Weakly breaking this
symmetry generates a gap on the surface, resulting in charge carriers with
finite effective mass and exotic spin textures. Analogous manipulations of the
one-dimensional boundary states of a two-dimensional topological insulator are
also possible, but have yet to be observed in the leading candidate materials.
Here, we demonstrate experimentally that charge neutral monolayer graphene
displays a new type of quantum spin Hall (QSH) effect, previously thought to
exist only in TRS topological insulators, when it is subjected to a very large
magnetic field angled with respect to the graphene plane. Unlike in the TRS
case, the QSH presented here is protected by a spin-rotation symmetry that
emerges as electron spins in a half-filled Landau level are polarized by the
large in-plane magnetic field. The properties of the resulting helical edge
states can be modulated by balancing the applied field against an intrinsic
antiferromagnetic instability, which tends to spontaneously break the
spin-rotation symmetry. In the resulting canted antiferromagnetic (CAF) state,
we observe transport signatures of gapped edge states, which constitute a new
kind of one-dimensional electronic system with tunable band gap and associated
spin-texture.


title: The Gould's Belt Very Large Array Survey I: The Ophiuchus complex

abstract:
  We present large-scale ($\sim$ 2000 square arcminutes), deep ($\sim$ 20
$\mu$Jy), high-resolution ($\sim$ 1$''$) radio observations of the Ophiuchus
star-forming complex obtained with the Karl G.\ Jansky Very Large Array at
$\lambda$ = 4 and 6 cm. In total, 189 sources were detected, 56 of them
associated with known young stellar sources, and 4 with known extragalactic
objects; the other 129 remain unclassified, but most of them are most probably
background quasars. The vast majority of the young stars detected at radio
wavelengths have spectral types K or M, although we also detect 4 objects of
A/F/B types and 2 brown dwarf candidates. At least half of these young stars
are non-thermal (gyrosynchrotron) sources, with active coronas characterized by
high levels of variability, negative spectral indices, and (in some cases)
significant circular polarization. As expected, there is a clear tendency for
the fraction of non-thermal sources to increase from the younger (Class 0/I or
flat spectrum) to the more evolved (Class III or weak line T Tauri) stars. The
young stars detected both in X-rays and at radio wavelengths broadly follow a
G\"udel-Benz relation, but with a different normalization than the most
radio-active types of stars. Finally, we detect a $\sim$ 70 mJy compact
extragalactic source near the center of the Ophiuchus core, which should be
used as gain calibrator for any future radio observations of this region.


title:
Negative Energy: Why Interdisciplinary Physics Requires Multiple
  Ontologies

abstract:
  Much recent work in physics education research has focused on ontological
metaphors for energy, particularly the substance ontology and its pedagogical
affordances. The concept of negative energy problematizes the substance
ontology for energy, but in many instructional settings, the specific
difficulties around negative energy are outweighed by the general advantages of
the substance ontology. However, we claim that our interdisciplinary setting (a
physics class that builds deep connections to biology and chemistry) leads to a
different set of considerations and conclusions. In a course designed to draw
interdisciplinary connections, the centrality of chemical bond energy in
biology necessitates foregrounding negative energy from the beginning. We argue
that the emphasis on negative energy requires a combination of substance and
location ontologies. The location ontology enables energies both "above" and
"below" zero. We present preliminary student data that illustrate difficulties
in reasoning about negative energy, and the affordances of the location
metaphor.


title: The statistical nature of the brightest group galaxies

abstract:
  We examine the statistical properties of the brightest group galaxies (BGGs)
using a complete spectroscopic sample of groups/clusters of galaxies selected
from the Data Release 7 of the Sloan Digital Sky Survey. We test whether BGGs
and other bright members of groups are consistent with an ordered population
among the total population of group galaxies. We find that the luminosity
distributions of BGGs do not follow the predictions from the order statistics
(OS). The average luminosities of BGGs are systematically brighter than OS
predictions. On the other hand, by properly taking into account the brightening
effect of the BGGs, the luminosity distributions of the second brightest
galaxies are in excellent agreement with the expectations of OS. The
brightening of BGGs relative to the OS expectation is consistent with a
scenario that the BGGs on average have over-grown about 20 percent masses
relative to the other member galaxies. The growth ($\Delta M$) is not
stochastic but correlated with the magnitude gap ($G_{1,2}$) between the
brightest and the second brightest galaxy. The growth ($\Delta M$) is larger
for the groups having more prominent BGGs (larger $G_{1,2}$) and averagely
contributes about 30 percent of the final $G_{1,2}$ of the groups of galaxies.


title: Polynomiality for Bin Packing with a Constant Number of Item Types

abstract:
  We consider the bin packing problem with d different item sizes s_i and item
multiplicities a_i, where all numbers are given in binary encoding. This
problem formulation is also known as the 1-dimensional cutting stock problem.
  In this work, we provide an algorithm which, for constant d, solves bin
packing in polynomial time. This was an open problem for all d >= 3.
  In fact, for constant d our algorithm solves the following problem in
polynomial time: given two d-dimensional polytopes P and Q, find the smallest
number of integer points in P whose sum lies in Q.
  Our approach also applies to high multiplicity scheduling problems in which
the number of copies of each job type is given in binary encoding and each type
comes with certain parameters such as release dates, processing times and
deadlines. We show that a variety of high multiplicity scheduling problems can
be solved in polynomial time if the number of job types is constant.


title:
Additional Invariants and Statistical Equilibria for the 2D Euler
  Equations on a spherical domain

abstract:
  The role of the domain geometry for the statistical mechanics of 2D Euler
flows is investigated. It is shown that for a spherical domain, there exists
invariant subspaces in phase space which yield additional angular momentum,
energy and enstrophy invariants. The microcanonical measure taking into account
these invariants is built and a mean-field, Robert-Sommeria-Miller theory is
developed in the simple case of the energy-enstrophy measure. The variational
problem is solved analytically and a partial energy condensation is obtained.
The thermodynamic properties of the system are also discussed.


title: On the positive and negative inertia of weighted graphs

abstract:
  The number of the positive, negative and zero eigenvalues in the spectrum of
the (edge)-weighted graph $G$ are called positive inertia index, negative
inertia index and nullity of the weighted graph $G$, and denoted by $i_+(G)$,
$i_-(G)$, $i_0(G)$, respectively. In this paper, the positive and negative
inertia index of weighted trees, weighted unicyclic graphs and weighted
bicyclic graphs are discussed, the methods of calculating them are obtained.


title:
Nonspinning black hole-neutron star mergers: a model for the amplitude
  of gravitational waveforms

abstract:
  Black hole-neutron star binary mergers display a much richer phenomenology
than black hole-black hole mergers, even in the relatively simple case -
considered in this paper - in which both the black hole and the neutron star
are nonspinning. When the neutron star is tidally disrupted, the gravitational
wave emission is radically different from the black hole-black hole case and it
can be broadly classified in two groups, depending on the spatial extent of the
disrupted material. We present a phenomenological model for the gravitational
waveform amplitude in the frequency domain that encompasses the three possible
outcomes of the merger: no tidal disruption, "mild", and "strong" tidal
disruption. The model is calibrated to general relativistic numerical
simulations using piecewise polytropic neutron star equations of state. It
should prove useful to extract information on the nuclear equation of state
from future gravitational-wave observations, and also to obtain more accurate
estimates of black hole-neutron star merger event rates in second- and
third-generation interferometric gravitational-wave detectors. We plan to
extend and improve the model as longer and more accurate gravitational
waveforms become available, and we will make it publicly available online as a
Mathematica package. We also present in appendix analytical fits of the
projected KAGRA noise spectral density, that should be useful in data analysis
applications.


title:
Microstructure and Structural Phase Transitions in Iron-Based
  Superconductors

abstract:
  Crystal structures and microstructural features, such as structural phase
transitions, defect structures, chemical and structural inhomogeneities, are
known to have profound effects on the physical properties of superconducting
materials. Recently, a large amount of works on the structural properties of
Fe-based high-Tc superconductors have been published. This review article will
mainly focus on typical microstructural features in samples that have been well
characterized by physical measurements. (a) Certain common structural features
are discussed. In particular, crystal structural features for different
superconducting families, local structural distortions in the Fe2Pn2 (Pn=P, As,
Sb) or Fe2Ch2 (Ch=S, Se, Te) blocks, and structural transformations in the 122
system. (b) In FeTe(Se) (11-family), the superconductivity, chemical and
structural inhomogeneities are investigated and discussed in correlation with
superconductivity. (c) In K0.8Fe1.6+xSe2 system, we focus on typical compounds
with emphasis on Fe-vacancy order and phase separations. The microstructural
features in other superconducting materials are also briefly discussed.


title:
A THz time-domain susceptibility for superconductors including
  strong-current effects

abstract:
  Finite-difference time-domain methods are increasingly being used to develop,
model and analyze the response of materials, including engineered metamaterials
that may contain superconductors. Though simple and useful expressions for the
time-domain susceptibility exist for basic metals and dielectrics, the
time-domain response for a superconductor has not been developed, mainly
because the frequency-dependent expressions themselves are rather complex. In
this paper we present a simple approximate expression for the time-domain
susceptibility of a superconductor for the hbar/2Delta time scale (where Delta
is the BCS energy gap) that fulfills causality requirements, and demonstrate
its ability to model the transmission and reflection of a fully-gapped
superconductor in the THz region. By allowing Delta to be a function of
current, we also show how this model function can be used to describe nonlinear
microwave response in superconductors.


title: A Finite Element Method for the Fractional Sturm-Liouville Problem

abstract:
  In this work, we propose an efficient finite element method for solving
fractional Sturm-Liouville problems involving either the Caputo or
Riemann-Liouville derivative of order $\alpha\in(1,2)$ on the unit interval
$(0,1)$. It is based on novel variational formulations of the eigenvalue
problem. Error estimates are provided for the finite element approximations of
the eigenvalues. Numerical results are presented to illustrate the efficiency
and accuracy of the method. The results indicate that the method can achieve a
second-order convergence for both fractional derivatives, and can provide
accurate approximations to multiple eigenvalues simultaneously.


title: Framing functions and strengthened version of Dehn's lemma

abstract:
  We give a lower estimate of the framing function of knots, and prove a
strengthened version of Dehn's lemma conjectured by Greene-Wiest.


title: Periodic knots and Heegaard Floer correction terms

abstract:
  We derive new obstructions to periodicity of classical knots by employing the
Heegaard Floer correction terms of the finite cyclic branched covers of the
knots. Applying our results to two fold covers, we demonstrate through numerous
examples that our obstructions are successful where many existing periodicity
obstructions fail. A combination of previously known periodicity obstructions
and the results presented here, leads to a nearly complete (with the exception
of a single knot) classification of alternating, periodic, 12-crossing knots
with odd prime periods. For the case of alternating knots with 13, 14 and 15
crossings, we give a complete listing of all periodic knots with odd prime
periods greater than 3.


title: The ALHAMBRA survey: Discovery of a faint QSO at z = 5.41

abstract:
  We aim to illustrate the potentiality of the Advanced Large, Homogeneous
Area, Medium-Band Redshift Astronomical (ALHAMBRA) survey to investigate the
high redshift universe through the detection of quasi stellar objects (QSOs) at
redshifts larger than 5. The search for z>5 QSOs candidates was done by fitting
an extensive library of spectral energy distributions --including active and
non-active galaxy templates as well as stars-- to the photometric database of
the ALHAMBRA survey (composed of 20 optical medium-band plus the 3 broad-band
JHKs filters). Our selection over ~1 square degree of ALHAMBRA data (~1/4 of
the total area covered by the survey), combined with GTC/OSIRIS spectroscopy,
has yielded the identification of an optically faint QSO at very high redshift
(z = 5.41). The QSO has an absolute magnitude of ~-24 at the 1450{\AA}
continuum, a bolometric luminosity of ~2x10^46 erg/s and an estimated black
hole mass of ~10^8 Msolar. This QSO adds itself to a reduced number of known UV
faint sources at these redshifts. The preliminary derived space density is
compatible with the most recent determinations of the high-z QSO luminosity
functions (QLF). This new detection shows how ALHAMBRA, as well as forthcoming
well designed photometric surveys, can provide a wealth of information on the
origin and early evolution of this kind of objects.


title:
Model-Based Policy Gradients with Parameter-Based Exploration by
  Least-Squares Conditional Density Estimation

abstract:
  The goal of reinforcement learning (RL) is to let an agent learn an optimal
control policy in an unknown environment so that future expected rewards are
maximized. The model-free RL approach directly learns the policy based on data
samples. Although using many samples tends to improve the accuracy of policy
learning, collecting a large number of samples is often expensive in practice.
On the other hand, the model-based RL approach first estimates the transition
model of the environment and then learns the policy based on the estimated
transition model. Thus, if the transition model is accurately learned from a
small amount of data, the model-based approach can perform better than the
model-free approach. In this paper, we propose a novel model-based RL method by
combining a recently proposed model-free policy search method called policy
gradients with parameter-based exploration and the state-of-the-art transition
model estimator called least-squares conditional density estimation. Through
experiments, we demonstrate the practical usefulness of the proposed method.


title:
Primordial blackholes and gravitational waves for an inflection-point
  model of inflation

abstract:
  In this article we provide a new closed relationship between cosmic abundance
of primordial gravitational waves and primordial blackholes originated from
initial inflationary perturbations for inflection-point models of inflation
where inflation occurs below the Planck scale. The current Planck constraint on
tensor-to-scalar ratio, running of the spectral tilt, and from the abundance of
dark matter content in the universe, we can deduce a strict bound on the
current abundance of primordial blackholes to be within a range, $9.99712\times
10^{-3}<\Omega_{PBH}h^{2}<9.99736\times 10^{-3}$.


title: Kelvin-Helmholtz instability of a coronal streamer

abstract:
  The shear-flow-driven instability can play an important role in energy
transfer processes in coronal plasma. We present for the first time the
observation of a kink-like oscillation of a streamer probably caused by the
streaming kinkmode Kelvin-Helmholtz instability. The wave-like behavior of the
streamer was observed by Large Angle and Spectrometric Coronagraph Experiment
(LASCO) C2 and C3 aboard SOlar and Heliospheric Observatory (SOHO). The
observed wave had a period of about 70 to 80 minutes, and its wavelength
increased from 2 Rsun to 3 Rsun in about 1.5 hours. The phase speeds of its
crests and troughs decreased from 406 \pm 20 to 356 \pm 31kms^{-1} during the
event. Within the same heliocentric range, the wave amplitude also appeared to
increase with time. We attribute the phenomena to the MHD Kelvin-Helmholtz
instability which occur at a neutral sheet in a fluid wake. The free energy
driving the instability is supplied by the sheared flow and sheared magnetic
field across the streamer plane. The plasma properties of the local environment
of the streamer were estimated from the phase speed and instability threshold
criteria.


title:
Broadband radio circular polarization spectrum of the relativistic jet
  in PKS B2126-158

abstract:
  We present full-Stokes radio polarization observations of the quasar PKS
B2126-158 (z=3.268) from 1 to 10 GHz using the Australia Telescope Compact
Array. The source has large fractional circular polarization, m_c \equiv |V|/I,
detected at high significance across the entire band (from 15 to 90\sigma per
128 MHz sub-band). This allows us to construct the most robust circular
polarization (CP) spectrum of an AGN jet to date. We find m_c \propto
\nu^{+0.60\pm0.03} from 1.5 to 6.5 GHz, with a peak of m_c ~ 1% before the
spectrum turns over somewhere between 6.5 and 8 GHz, above which m_c \propto
\nu^{-3.0\pm0.4}. The fractional linear polarization (p) varies from <~0.2% to
~1% across our frequency range and is strongly anti-correlated with the
fractional CP, with a best-fit power law giving m_c \propto p^{-0.24\pm0.03}.
This is the first clear relation between the observed linear and circular
polarisations of an AGN jet, revealing the action of Faraday conversion of
linear polarization (LP) to CP within the jet. More detailed modelling in
conjunction with high-spatial resolution observations are required to determine
the true driving force behind the conversion (i.e. magnetic twist or internal
Faraday rotation). In particular determining whether the observed Faraday
rotation is internal or entirely external to the jet is key to this goal. The
simplest interpretation of our observations favours some internal Faraday
rotation, implying that Faraday rotation-driven conversion of LP to CP is the
dominant CP generation mechanism. In this case, a small amount of
vector-ordered magnetic field along the jet axis is required, along with
internal Faraday rotation from the low energy end of the relativistic electron
energy spectrum in an electron-proton dominated jet.


title: Relativistic Black-Scholes model

abstract:
  Black-Scholes equation, after a certain coordinate transformation, is
equivalent to the heat equation. On the other hand the relativistic extension
of the latter, the telegraphers equation, can be derived from the Euclidean
version of the Dirac equation. Therefore the relativistic extension of the
Black-Scholes model follows from relativistic quantum mechanics quite
naturally. We investigate this particular model for the case of European
vanilla options. Due to the notion of locality incorporated in this way one
finds that the volatility frown-like effect appears when comparing to the
original Black-Scholes model.


title: Extremely Large Images: Considerations for Contemporary Approach

abstract:
  The new widefield radio telescopes, such as: ASKAP,MWA, LOFAR, eVLA and SKA;
will produce spectral-imaging data-cubes (SIDC) of unprecedented volumes in the
order of hundreds of Petabytes. Servicing such data as images to the end-user
may encounter challenges unforeseen during the development of IVOA SIAP. We
discuss the requirements for extremely large SIDC, and in this light we analyse
the applicability of approach taken in the ISO/IEC 15444 (JPEG2000) standards.


title: The Feynman $i \epsilon$ in String Theory

abstract:
  The Feynman $i\varepsilon$ is an important ingredient in defining
perturbative scattering amplitudes in field theory. Here we describe its analog
in string theory. Roughly one takes the string worldsheet to have Lorentz
signature when a string is going on-shell although it has Euclidean signature
generically.


title: A Possible Detection of Solar Gamma-Rays by the Ground Level Detector

abstract:
  On March 7, 2011 from 19:48:00 to 20:03:00 UT, the solar neutron telescope
located at Mt. Sierra Negra, Mexico (4,600m) observed a 8.8sigma enhancement.
In this paper, we would like to try to explain this enhancement by a hypothesis
that a few GeV gamma-rays arrived at the top of the mountain produced by the
Sun. We postulate that protons were accelerated at the shock front. They
precipitate at the solar surface and produced those gamma-rays. If hypothesis
is confirmed, this enhancement is the first sample of GeV gamma-rays observed
by a ground level detector.


title: Time-symmetric quantization in spacetimes with event horizons

abstract:
  The standard quantization formalism in spacetimes with event horizons implies
a non-unitary evolution of quantum states, as initial pure states may evolve
into thermal states. This phenomenon is behind the famous black hole
information loss paradox which provoked long-standing debates on the
compatibility of quantum mechanics and gravity. In this paper we demonstrate
that within an alternative time-symmetric quantization formalism thermal
radiation is absent and states evolve unitarily in spacetimes with event
horizons. We also discuss the theoretical consistency of the proposed
formalism. We explicitly demonstrate that the theory preserves the
microcausality condition and suggest a "reinterpretation postulate" to resolve
other apparent pathologies associated with negative energy states. Accordingly
as there is a consistent alternative, we argue that choosing to use
time-asymmetric quantization is a necessary condition for the black hole
information loss paradox.


title: An extension of the Dirac theory of constraints

abstract:
  Constructions introduced by Dirac for singular Lagrangians are extended and
reinterpreted to cover cases when kernel distributions are either nonintegrable
or of nonconstant rank, and constraint sets need not be closed.


title: Generalized Parton Distributions for the Proton in AdS/QCD

abstract:
  We present a study of proton GPDs in both momentum and position spaces using
proton wavefunction obtained from AdS/ QCD. Here we consider the soft wall
model. The results are compared with a phenomenological model of proton GPDs.


title:
Study Of Casleo Clear Sky Aerosol Loads In 2011 From One Year Of Aeronet
  Quality Assured Data

abstract:
  In this work we analyze one year observation of an Aeronet (GSFC-NASA Aerosol
Robotic Network) sun-photometer installed on January 11, 2011 in CASLEO and
being operational up to date. The main goal of placing the instrument in this
location is to characterize the aerosol loads of this astronomical complex
which is close and has the same sky characteristics of El Leoncito (31deg
43.33' South - 69deg 15.93' West, 2552 m ASL) one of the southern candidate
site for Cherenkov Telescope Array (CTA). The low aerosol optical depth (AOD)
annual mean of 0.038 measured at 500 nm shows exceptional clear sky quality.
Data is compared with the measurements being done at Mauna Loa (19deg 32.34'
North, 55deg 34.68' West, 3397 m ASL), where Aeronet reference instruments are
being re-calibrated two to four times per year. Long term MODIS observations
are studied, showing that the site is far enough to biomass burning transport
regions to be affected by its influence.


title:
Perspective: Coulomb fluids -- weak coupling, strong coupling, in
  between and beyond

abstract:
  We present a personal view on the current state of statistical mechanics of
Coulomb fluids with special emphasis on the interactions between macromolecular
surfaces, concentrating on the weak and the strong coupling limits. Both are
introduced for a (primitive) counterion-only system in the presence of
macroscopic, uniformly charged boundaries, where they can be derived
systematically. Later we show how this formalism can be generalized to the
cases with additional characteristic length scales that introduce new coupling
parameters into the problem. These cases most notably include asymmetric ionic
mixtures with mono- and multivalent ions that couple differently to charged
surfaces, ions with internal charge (multipolar) structure and finite static
polarizability, where weak and strong coupling limits can be constructed by
analogy with the counterion-only case and lead to important new insights into
their properties that can not be derived by any other means.

categories: cond-mat.soft cond-mat.stat-mech physics.bio-ph physics.chem-ph


title:
Waves in the unseen : theory of spin excitations in a quantum spin
  nematic

abstract:
  The idea that a quantum magnet could act like a liquid crystal, breaking
spin-rotation symmetry without breaking time-reversal symmetry, holds an
abiding fascination. However, the very fact that spin nematic states do not
break time-reversal symmetry renders them "invisible" to the most common probes
of magnetism - they do not exhibit magnetic Bragg peaks, a static splitting of
lines in NMR spectra, or oscillations in muSR. Nonetheless, as a consequence of
breaking spin-rotation symmetry, spin-nematic states do possess a
characteristic spectrum of dispersing excitations which could be observed in
experiment. With this in mind, we develop a symmetry-based description of
long-wavelength excitations in a spin-nematic state, based on an SU(3)
generalisation of the quantum non-linear sigma model. We use this field theory
to make explicit predictions for inelastic neutron scattering, and argue that
the wave-like excitations it predicts could be used to identify the symmetries
broken by the otherwise unseen spin-nematic order.


title: Every matrix is a product of Toeplitz matrices

abstract:
  We show that every n-by-n matrix is generically a product of [n/2] + 1
Toeplitz matrices and always a product of at most 2n+5 Toeplitz matrices. The
same result holds true if the word "Toeplitz" is replaced by "Hankel", and the
generic bound [n/2] + 1 is sharp. We will see that these decompositions into
Toeplitz or Hankel factors are unusual: We may not in general replace the
subspace of Toeplitz or Hankel matrices by an arbitrary (2n-1)-dimensional
subspace of n-by-n matrices. Furthermore such decompositions do not exist if we
require the factors to be symmetric Toeplitz, persymmetric Hankel, or circulant
matrices, even if we allow an infinite number of factors. Lastly, we discuss
how the Toeplitz and Hankel decompositions of a generic matrix may be computed
by either (i) solving a system of linear and quadratic equations if the number
of factors is required to be [n/2] + 1, or (ii) Gaussian elimination in O(n^3)
time if the number of factors is allowed to be 2n.


title:
Chamber Surface Roughness and Electron Cloud for the Advanced Photon
  Source Superconducting Undulator

abstract:
  The electron cloud is a possible heat source in the superconducting undulator
(SCU) designed for the Advanced Photon Source (APS), a 7-GeV electron
synchrotron radiation source at Argonne National Laboratory. In electron cloud
generation extensive research has been done, and is continuing, to understand
the secondary electron component. However, little work has been done to
understand the parameters of photoemission in the accelerator environment. To
better understand the primary electron generation in the APS; a beamline at the
Australian Light Source synchrotron was used to characterize two samples of the
Al APS vacuum chamber. The total photoelectron yield and the photoemission
spectra were measured. Four parameters were varied: surface roughness, sample
temperature, incident photon energy, and incident photon angle, with their
results presented here.


title: Hajlasz Gradients Are Upper Gradients

abstract:
  Let $(X, d, \mu)$ be a metric measure space, with $\mu$ a Borel regular
measure. In this paper, we prove that, if $u\in
L^1_{{\mathop\mathrm{\,loc\,}}}(X)$ and $g$ is a Haj{\l}asz gradient of $u$,
then there exists $\widetilde u$ such that $\widetilde u=u$ almost everywhere
and $4g$ is a $p$-weak upper gradient of $\widetilde u$. This result avoids a
priori assumption on the quasi-continuity of $u$ used in [Rev. Mat.
Iberoamericana 16 (2000), 243-279]. As an application, an embedding of the
Morrey-type function spaces based on Haj{\l}asz-gradients into the
corresponding function spaces based on upper gradients is obtained. We also
introduce the notion of local Haj{\l}asz gradient, and investigate the
relations between local Haj{\l}asz gradient and upper gradient.


title:
Updated photometry and orbital period analysis for the polar
  \objectname{am herculis} on the upper edge of the period gap

abstract:
  Twenty-one new optical light curves, including five curves obtained in 2009
and sixteen curves detected from the AAVSO International Database spanning from
1977 to 2011, demonstrate 16 new primary minimum light times in the high state.
Furthermore, seven newly found low-state transient events from 2006 to 2009
were discovered, consisting of five Gaussian-shaped events and two events with
an exponential form with decay timescales of $<$0.005 days; these timescales
are one order of magnitude shorter than those of previous X-ray flare events.
In the state transition, two special events were detected: a "disrupted event"
with an amplitude of $\sim$ 2 mag and a duration of $\sim$ 72 minutes and
continuing R-band twin events larger than all known R-band flares detected in
M-type red dwarfs. All 45 available high-state data points spanning over 35 yr
were used to construct an updated O-C diagram of \objectname{AM Herculis},
which clearly shows a significant sine-like variation with a period of 12-15 yr
and an amplitude of 6-9 minutes. Using the inspected physical parameters of the
donor star, the secular variation in the O-C diagram cannot be interpreted by
any decided angular momentum loss mechanism, but can satisfy the condition
$\tau_{\dot{\rm M}_{2}}\simeq\tau_{\rm KH}>>\tau_{\dot{\rm R}_{\rm 2}}$, which
is required by numerical calculations of the secular evolution of cataclysmic
variables. In order to explain the prominent periodic modulation, three
plausible mechanisms - spot motion, the light travel-time effect, and magnetic
active cycles - are discussed in detail.


title:
Full Field Supercritical Angle Fluorescence Microscopy for live cell
  imaging

abstract:
  We introduce a full field fluorescence imaging technique with axial
confinement of about 100 nm at the sample/substrate interface. Contrary to
standard surface imaging techniques, this confinement is obtained through
emission filtering. This technique is based on supercritical emission
selectivity. It can be implemented on any epifluorescence microscope with a
commercial high numerical aperture objective and offers a real time surface
imaging capability. This technique is of particular interest for live cell
membrane and adhesion studies. Using HEK cells, we show that one can observe
simultaneously the surface and in-depth cell phenomena.


title: Statistical Physics: a Short Course for Electrical Engineering Students

abstract:
  This is a set of lecture notes of a course on statistical physics and
thermodynamics, which is oriented, to a certain extent, towards electrical
engineering students. The main body of the lectures is devoted to statistical
physics, whereas much less emphasis is given to the thermodynamics part. In
particular, the idea is to let the most important results of thermodynamics
(most notably, the laws of thermodynamics) to be obtained as conclusions from
the derivations in statistical physics. Beyond the variety of central topics in
statistical physics that are important to the general scientific education of
the EE student, special emphasis is devoted to subjects that are vital to the
engineering education concretely. These include, first of all, quantum
statistics, like the Fermi-Dirac distribution, as well as diffusion processes,
which are both fundamental for deep understanding of semiconductor devices.
Another important issue for the EE student is to understand mechanisms of noise
generation and stochastic dynamics in physical systems, most notably, in
electric circuitry. Accordingly, the fluctuation-dissipation theorem of
statistical mechanics, which is the theoretical basis for understanding thermal
noise processes in systems, is presented from a signals--and--systems point of
view, in a way that would hopefully be understandable and useful for an
engineering student, and well connected to other courses in the electrcial
engineering curriculum like courses on random priocesses. The quantum regime,
in this context, is important too and hence provided as well. Finally, we touch
very briefly upon some relationships between statistical mechanics and
information theory, which is the theoretical basis for communications
engineering, and demonstrate how statistical-mechanical approach can be useful
in order for the study of information-theoretic problems.


title:
Illumination complexes, {\Delta}-zonotopes, and the polyhedral curtain
  theorem

abstract:
  Illumination complexes are examples of 'flat polyhedral complexes' which
arise if several copies of a convex polyhedron (convex body) Q are glued
together along some of their common faces (closed convex subsets of their
boundaries). A particularly nice example arises if Q is a {\Delta}-zonotope
(generalized rhombic dodecahedron), known also as the dual of the difference
body {\Delta} - {\Delta} of a simplex {\Delta}, or the dual of the convex hull
of the root system A_n. We demonstrate that the illumination complexes and
their relatives can be used as 'configuration spaces', leading to new 'fair
division theorems'. Among the central new results is the 'polyhedral curtain
theorem' (Theorem 3) which is a relative of both the 'ham sandwich theorem' and
the 'splitting necklaces theorem'.


title: The Site of the ASTRI SST-2M Telescope Prototype

abstract:
  ASTRI is a Flagship Project financed by the Italian Ministry of Education,
University and Research, and led by the Italian National Institute of
Astrophysics, INAF. Primary goal of the ASTRI project is the design and
production of an end-to-end prototype of Small Size Telescope for the CTA
(Cherenkov Telescope Array) in a dual-mirror configuration (SST-2M) equipped
with a camera at the focal plane composed by an array of Silicon
Photo-Multipliers and devoted to the investigation of the highest gamma-ray
energy band. The ASTRI SST-2M prototype will be placed at the INAF M.G.
Fracastoro observing station in Serra La Nave on the Etna Mountain near
Catania, Italy. After the verification tests, devoted to probe the
technological solutions adopted, the ASTRI SST-2M prototype will perform
scientific observations on the Crab Nebula and on some of the brightest TeV
sources. Here we present the Serra La Nave site, its meteorological and weather
conditions, the sky darkness and visibility, and the complex of auxiliary
instrumentation that will be used on site to support the calibration and
science verification phase as well as the regular data reconstruction and
analysis of the ASTRI SST-2M prototype.


title:
Measurement-Based Quantum Computation on Two-Body Interacting Qubits
  with Adiabatic Evolution

abstract:
  A cluster state cannot be a unique ground state of a two-body interacting
Hamiltonian. Here, we propose the creation of a cluster state of logical qubits
encoded in spin-1/2 particles by adiabatically weakening two-body interactions.
The proposal is valid for any spatial dimensional cluster states. Errors
induced by thermal fluctuations and adiabatic evolution within finite time can
be eliminated ensuring fault-tolerant quantum computing schemes.


title:
Two-dimensional von Neumann--Wigner potentials with a multiple positive
  eigenvalue

abstract:
  By the Moutard transformation method we construct two-dimensional Schrodinger
operators with real smooth potential decaying at infinity and with a multiple
positive eigenvalue. These potentials are rational functions of spatial
variables and their sines and cosines.


title: The ASTRI SST-2M Prototype: Camera and Electronics

abstract:
  ASTRI is a Flagship Project financed by the Italian Ministry of Education,
University and Research, and led by INAF, the Italian National Institute of
Astrophysics. The primary goal of the ASTRI project is the realization of an
end-to-end prototype of a Small Size Telescope for the Cherenkov Telescope
Array. The prototype, named ASTRI SST-2M, is based on a completely new double
mirror optics design and will be equipped with a camera made of a matrix of
SiPM detectors. Here we describe the ASTRI SST-2M camera concept: basic idea,
detectors, electronics, current status and some results coming from experiments
in lab.


title:
A polynomial-time algorithm for the ground state of 1D gapped local
  Hamiltonians

abstract:
  Computing ground states of local Hamiltonians is a fundamental problem in
condensed matter physics. We give the first randomized polynomial-time
algorithm for finding ground states of gapped one-dimensional Hamiltonians: it
outputs an (inverse-polynomial) approximation, expressed as a matrix product
state (MPS) of polynomial bond dimension. The algorithm combines many
ingredients, including recently discovered structural features of gapped 1D
systems, convex programming, insights from classical algorithms for 1D
satisfiability, and new techniques for manipulating and bounding the complexity
of MPS. Our result provides one of the first major classes of Hamiltonians for
which computing ground states is provably tractable despite the exponential
nature of the objects involved.


title: Hamiltonian replica-exchange in GROMACS: a flexible implementation

abstract:
  A simple and general implementation of Hamiltonian replica exchange for the
popular molecular-dynamics software GROMACS is presented. In this
implementation, arbitrarily different Hamiltonians can be used for the
different replicas without incurring in any significant performance penalty.
The implementation was validated on a simple toy model - alanine dipeptide in
water - and applied to study the rearrangement of an RNA tetraloop, where it
was used to compare recently proposed force-field corrections.

categories: physics.comp-ph cond-mat.stat-mech physics.bio-ph physics.chem-ph


title: An Improved Estimator In Systematic Sampling

abstract:
  In this paper we have adapted Bahl and Tuteja (1991) estimator in systematic
sampling using auxiliary information. Using Bedi (1996) transformation an
improved estimator is also proposed under systematic sampling. The expressions
of bias and mean square error up to the first order of approximation are
derived. It has been shown that the proposed estimator performs better than
many existing estimators. A numerical example is included to support the
theoretical results.


title: The long wavelength view of GG Tau A: Rocks in the Ring World

abstract:
  We present the first detection of GG Tau A at centimeter-wavelengths, made
with the Arcminute Microkelvin Imager Large Array (AMI-LA) at a frequency of 16
GHz ({\lambda} = 1.8 cm). The source is detected at > 6 {\sigma}_{rms} with an
integrated flux density of S = 249+/-45 {\mu}Jy. We use these new
centimetre-wave data, in conjunction with additional measurements compiled from
the literature, to investigate the long wavelength tail of the dust emission
from this unusual proto-planetary system. We use an MCMC based method to
determine maximum likelihood parameters for a simple parametric spectral model
and consider the opacity and mass of the dust contributing to the microwave
emission. We derive a dust mass of approximately 0.1 solar masses, constrain
the dimensions of the emitting region and find that the opacity index at
{\lambda} > 7mm is less than unity, implying a contribution to the dust
population from grains exceeding 4 cm in size. We suggest that this indicates
coagulation within the GG Tau A system has proceeded to the point where dust
grains have grown to the size of small rocks with dimensions of a few
centimetres. Considering the relatively young age of the GG Tau association, in
combination with the low derived disk mass, we suggest that this system may
provide a useful test case for rapid core accretion planet formation models.


title: An Arrow-type result for inferring a species tree from gene trees

abstract:
  The reconstruction of a central tendency `species tree' from a large number
of conflicting gene trees is a central problem in systematic biology. Moreover,
it becomes particularly problematic when taxon coverage is patchy, so that not
all taxa are present in every gene tree. Here, we list four desirable
properties that a method for estimating a species tree from gene trees should
have. We show that while these can be achieved when taxon coverage is complete
(by the Adams consensus method), they cannot all be satisfied in the more
general setting of partial taxon coverage.


title:
Ion heating dynamics in solid buried layer targets irradiated by
  ultra-short intense laser pulses

abstract:
  We investigate bulk ion heating in solid buried layer targets irradiated by
ultra-short laser pulses of relativistic intensities using particle-in-cell
simulations. Our study focuses on a CD2-Al-CD2 sandwich target geometry. We
find enhanced deuteron ion heating in a layer compressed by the expanding
aluminium layer. A pressure gradient created at the Al-CD2 interface pushes
this layer of deuteron ions towards the outer regions of the target. During its
passage through the target, deuteron ions are constantly injected into this
layer. Our simulations suggest that the directed collective outward motion of
the layer is converted into thermal motion inside the layer, leading to
deuteron temperatures higher than those found in the rest of the target. This
enhanced heating can already be observed at laser pulse durations as low as 100
femtoseconds. Thus, detailed experimental surveys at repetition rates of
several ten laser shots per minute are in reach at current high-power laser
systems, which would allow for probing and optimizing the heating dynamics.


title:
A Nehari manifold for non-local elliptic operator with concave-convex
  non-linearities and sign-changing weight function

abstract:
  In this article, we study the existence and multiplicity of non-negative
solutions of following $p$-fractional equation: $$ \quad
\left\{\begin{array}{lr}\ds
  \quad - 2\int_{\mb R^n}\frac{|u(y)-u(x)|^{p-2}(u(y)-u(x))}{|x-y|^{n+p\al}}
dxdy = \la h(x)|u|^{q-1}u+ b(x)|u|^{r-1} u \; \text{in}\; \Om
  \quad \quad \quad \quad u \geq 0 \; \mbox{in}\; \Om,\quad u\in W^{\al,p}(\mb
R^n),
  \quad \quad\quad \quad\quad u =0\quad\quad \text{on} \quad \mb R^n\setminus
\Om \end{array} \right. $$ where $\Om$ is a bounded domain in $\mb R^n$, $p\geq
2$, $n> p\al$, $\al\in(0,1)$, $0< q<p-1 <r < \frac{np}{n-ps}-1$, $\la>0$ and
$h$, $b$ are sign changing smooth functions. We show the existence of solutions
by minimization on the suitable subset of Nehari manifold using the fibering
maps. We find that there exists $\la_0$ such that for $\la\in (0,\la_0)$, it
has at least two solutions.


title:
Quantitative magnetic imaging at the nanometer scale by ballistic
  electron magnetic microscopy

abstract:
  We demonstrate quantitative ballistic electron magnetic microscopy (BEMM)
imaging of simple model Fe(001) nanostructures. We use in situ nanostencil
shadow mask resistless patterning combined with molecular beam epitaxy
deposition to prepare under ultra-high vacuum conditions nanostructured
epitaxial Fe/Au/Fe/GaAs(001) spin-valves. In this epitaxial system, the
magnetization of the bottom Fe/GaAs(001) electrode is parallel to the [110]
direction, defining accurately the analysis direction for the BEMM experiments.
The large hot-electron magnetoresistance of the Fe/Au/Fe/GaAs(001) epitaxial
spin-valve allows us to image various stable magnetic configurations on the
as-grown Fe(001) microstructures with a high sensitivity, even for small
misalignments of both magnetic electrodes. The angular dependence of the
hot-electron magnetocurrent is used to convert magnetization maps calculated by
micromagnetic simulations into simulated BEMM images. The calculated BEMM
images and magnetization rotation profiles show quantitative agreement with
experiments and allow us to investigate the magnetic phase diagram of these
model Fe(001) microstructures. Finally, magnetic domain reversals are observed
under high current density pulses. This opens the way for further BEMM
investigations of current-induced magnetization dynamics.


title: SDP Duals without Duality Gaps for a Class of Convex Minimax Programs

abstract:
  In this paper we introduce a new dual program, which is representable as a
semi-definite linear programming problem, for a primal convex minimax
programming model problem and show that there is no duality gap between the
primal and the dual whenever the functions involved are SOS-convex polynomials.
Under a suitable constraint qualification, we derive strong duality results for
this class of minimax problems. Consequently, we present applications of our
results to robust SOS-convex programming problems under data uncertainty and to
minimax fractional programming problems with SOS-convex polynomials. We obtain
these results by first establishing sum of squares polynomial representations
of non-negativity of a convex max function over a system of SOS-convex
constraints. The new class of SOS-convex polynomials is an important subclass
of convex polynomials and it includes convex quadratic functions and separable
convex polynomials. The SOS-convexity of polynomials can numerically be checked
by solving semi-definite programming problems whereas numerically verifying
convexity of polynomials is generally very hard.


title: Characteristic classes of mixed Hodge modules and applications

abstract:
  These notes are an extended version of the authors' lectures at the 2013 CMI
Workshop "Mixed Hodge Modules and Their Applications". We give an overview,
with an emphasis on applications, of recent developments on the interaction
between characteristic class theories for singular spaces and Saito's theory of
mixed Hodge modules in the complex algebraic context.


title: Pairing in few-fermion systems with attractive interactions

abstract:
  We have studied quasi one-dimensional few-particle systems consisting of one
to six ultracold fermionic atoms in two different spin states with attractive
interactions. We probe the system by deforming the trapping potential and by
observing the tunneling of particles out of the trap. For even particle numbers
we observe a tunneling behavior which deviates from uncorrelated
single-particle tunneling indicating the existence of pair correlations in the
system. From the tunneling timescales we infer the differences in interaction
energies of systems with different number of particles which show a strong
odd-even effect, similar to the one observed for neutron separation experiments
in nuclei.


title: Multi-species mean-field spin-glasses. Rigorous results

abstract:
  We study a multi-species spin glass system where the density of each species
is kept fixed at increasing volumes. The model reduces to the
Sherrington-Kirkpatrick one for the single species case. The existence of the
thermodynamic limit is proved for all densities values under a convexity
condition on the interaction. The thermodynamic properties of the model are
investigated and the annealed, the replica symmetric and the replica symmetry
breaking bounds are proved using Guerra's scheme. The annealed approximation is
proved to be exact under a high temperature condition. We show that the replica
symmetric solution has negative entropy at low temperatures. We study the
properties of a suitably defined replica symmetry breaking solution and we
optimise it within a ziggurat ansatz. The generalized order parameter is
described by a Parisi-like partial differential equation.

categories: math-ph cond-mat.dis-nn cond-mat.stat-mech math.MP


title:
Damping and non-linearity of a levitating magnet in rotation above a
  superconductor

abstract:
  We study the dissipation of moving magnets in levitation above a
superconductor. The rotation motion is analyzed using optical tracking
techniques. It displays a remarkable regularity together with long damping time
up to several hours. The magnetic contribution to the damping is investigated
in detail by comparing 14 distinct magnetic configurations, and points towards
amplitude-dependent dissipation mechanisms. The non-linear dynamics of the
mechanical rotation motion is also revealed and described with an effective
Duffing model. The obtained picture of the coupling of levitating magnets to
their environment sheds light on their potential as ultra-low dissipation
mechanical oscillators for high precision physics.


title: On The Multinorm Principle For Finite Extensions

abstract:
  Let L_1 and L_2 be finite abelian extensions of a global field K. We compute
the obstruction to the multinorm principle for the pair L_1, L_2.


title: Lower bounds on geometric Ramsey functions

abstract:
  We continue a sequence of recent works studying Ramsey functions for
semialgebraic predicates in $\mathbb{R}^d$. A $k$-ary semialgebraic predicate
$\Phi(x_1,\ldots,x_k)$ on $\mathbb{R}^d$ is a Boolean combination of polynomial
equations and inequalities in the $kd$ coordinates of $k$ points
$x_1,\ldots,x_k\in\mathbb{R}^d$. A sequence $P=(p_1,\ldots,p_n)$ of points in
$\mathbb{R}^d$ is called $\Phi$-homogeneous if either $\Phi(p_{i_1},
\ldots,p_{i_k})$ holds for all choices $1\le i_1 < \cdots < i_k\le n$, or it
holds for no such choice. The Ramsey function $R_\Phi(n)$ is the smallest $N$
such that every point sequence of length $N$ contains a $\Phi$-homogeneous
subsequence of length $n$.
  Conlon, Fox, Pach, Sudakov, and Suk constructed the first examples of
semialgebraic predicates with the Ramsey function bounded from below by a tower
function of arbitrary height: for every $k\ge 4$, they exhibit a $k$-ary $\Phi$
in dimension $2^{k-4}$ with $R_\Phi$ bounded below by a tower of height $k-1$.
We reduce the dimension in their construction, obtaining a $k$-ary
semialgebraic predicate $\Phi$ on $\mathbb{R}^{k-3}$ with $R_\Phi$ bounded
below by a tower of height $k-1$.
  We also provide a natural geometric Ramsey-type theorem with a large Ramsey
function. We call a point sequence $P$ in $\mathbb{R}^d$ order-type homogeneous
if all $(d+1)$-tuples in $P$ have the same orientation. Every sufficiently long
point sequence in general position in $\mathbb{R}^d$ contains an order-type
homogeneous subsequence of length $n$, and the corresponding Ramsey function
has recently been studied in several papers. Together with a recent work of
B\'ar\'any, Matou\v{s}ek, and P\'or, our results imply a tower function of
$\Omega(n)$ of height $d$ as a lower bound, matching an upper bound by Suk up
to the constant in front of $n$.


title:
Approximate solutions for N-body Hamiltonians with identical particles
  in D dimensions

abstract:
  A method based on the envelope theory is presented to compute approximate
solutions for $N$-body Hamiltonians with identical particles in $D$ dimensions
($D\ge 2$). In some favorable cases, the approximate eigenvalues can be
analytically determined and can be lower or upper bounds. An application to a
$N$-body system with a minimal length is studied, and a semiclassical
interpretation of the generic formula obtained for the eigenvalues is given.


title: Spontaneous exciton dissociation in carbon nanotubes

abstract:
  Simultaneous photoluminescence and photocurrent measurements on individual
single-walled carbon nanotubes reveal spontaneous dissociation of excitons into
free electron-hole pairs. Correlation of luminescence intensity and
photocurrent shows that a significant fraction of excitons are dissociating
during their relaxation into the lowest exciton state. Furthermore, the
combination of optical and electrical signals also allows for extraction of the
absorption cross section and the oscillator strength. Our observations explain
the reasons for photoconductivity measurements in single-walled carbon
nanotubes being straightforward despite the large exciton binding energies.


title: Killing vector fields of constant length on compact hypersurfaces

abstract:
  We show that if a compact hypersurface $M \subset \mathbb{R}^{n+1}$, $n
\geq3$, admits a non zero Killing vector field $X$ of constant length then $n$
is even and $M$ is diffeomorphic to the unit hypersphere of $\mathbb{R}^{n+1}$.
Actually, we show that $M$ is a complex ellipsoid in $\mathbb{C}^{N} =
\mathbb{R}^{n+1}$. As an application we give a simpler proof of a recent
theorem due to S. Deshmukh \cite{De12}.


title: Random Binary Mappings for Kernel Learning and Efficient SVM

abstract:
  Support Vector Machines (SVMs) are powerful learners that have led to
state-of-the-art results in various computer vision problems. SVMs suffer from
various drawbacks in terms of selecting the right kernel, which depends on the
image descriptors, as well as computational and memory efficiency. This paper
introduces a novel kernel, which serves such issues well. The kernel is learned
by exploiting a large amount of low-complex, randomized binary mappings of the
input feature. This leads to an efficient SVM, while also alleviating the task
of kernel selection. We demonstrate the capabilities of our kernel on 6
standard vision benchmarks, in which we combine several common image
descriptors, namely histograms (Flowers17 and Daimler), attribute-like
descriptors (UCI, OSR, and a-VOC08), and Sparse Quantization (ImageNet).
Results show that our kernel learning adapts well to the different descriptors
types, achieving the performance of the kernels specifically tuned for each
image descriptor, and with similar evaluation cost as efficient SVM methods.


title:
Protected quantum computing: Interleaving gate operations with dynamical
  decoupling sequences

abstract:
  Implementing precise operations on quantum systems is one of the biggest
challenges for building quantum devices in a noisy environment. Dynamical
decoupling (DD) attenuates the destructive effect of the environmental noise,
but so far it has been used primarily in the context of quantum memories. Here,
we present a general scheme for combining DD with quantum logical gate
operations and demonstrate its performance on the example of an electron spin
qubit of a single nitrogen-vacancy center in diamond. We achieve process
fidelities >98% for gate times that are 2 orders of magnitude longer than the
unprotected dephasing time $T_{2}$.


title:
Dynamic Programming for controlled Markov families: abstractly and over
  Martingale Measures

abstract:
  We describe an abstract control-theoretic framework in which the validity of
the dynamic programming principle can be established in continuous time by a
verification of a small number of structural properties. As an application we
treat several cases of interest, most notably the lower-hedging and
utility-maximization problems of financial mathematics both of which are
naturally posed over ``sets of martingale measures''.


title: X-ray diffraction by magnetic charges (monopoles)

abstract:
  Magnetic charges, or magnetic monopoles, may form in the electronic structure
of magnetic materials where ions are deprived of symmetry with respect to
spatial inversion. Predicted in 2009, the strange magnetic, pseudoscalars have
recently been found different from zero in simulations of electronic structures
of some magnetically ordered, orthorhombic, lithium orthophosphates (LiMPO4).
We prove that magnetic charges in lithium orthophosphates diffract x-rays tuned
in energy to an atomic resonance, and to guide future experiments we calculate
appropriate unit-cell structure factors for monoclinic LiCoPO4 and orthorhombic
LiNiPO4.


title: Using a rotating magnetic guiding field for the 3He-129Xe-Comagnetometer

abstract:
  Our search for non-magnetic spin-dependent interactions is based on the
measurement of free precession of nuclear spin polarized 3He and 129Xe atoms in
a homogeneous magnetic guiding field of about 400 nT. We report on our approach
to perform an adiabatic rotation of the guiding field that allows us to
modulate possible non-magnetic spin-dependent interactions and to find an
optimization procedure for long transverse relaxation times T2* both for Helium
and Xenon.


title:
Total transmission and total reflection of acoustic wave by zero index
  metamaterials loaded with general solid defects

abstract:
  This work investigates acoustic wave transmission property through a zero
index metamaterials (ZIM) waveguide embedded with a general solid defect. Total
transmission and total reflection can be achieved by adjusting the parameters
of the solid defect. We comprehensively study how longitudinal/transverse wave
speeds of the solid defect affect the acoustic wave propagation through the
waveguide. A two-dimensional (2D) acoustic crystals (ACs) system with zero
index is used to realize these intriguing transmission properties. Thus, our
work provides more possibilities to manipulate acoustic wave propagation
through ZIM.


title: Effect of three-nucleon interaction in p-3He elastic scattering

abstract:
  We present a detailed study of the effect of different three-nucleon
interaction models in p-3He elastic scattering at low energies. In particular,
two models have been considered: one derived from effective field theory at
next-to-next-to-leading order and one derived from a more phenomenological
point of view -- the so-called Illinois model. The four-nucleon scattering
observables are calculated using the Kohn variational principle and the
hyperspherical harmonics technique and the results are compared with available
experimental data. We have found that the inclusion of either one of the other
force model improves the agreement with the experimental data, in particular
for the proton vector analyzing power.


title: Novel Experimentally Observed Phenomena in Soft Matter

abstract:
  Soft materials such as colloidal suspensions, polymer solutions and liquid
crystals are constituted by mesoscopic entities held together by weak forces.
Their mechanical moduli are several orders of magnitude lower than those of
atomic solids. The application of small to moderate stresses to these materials
results in the disruption of their microstructures. The resulting flow is
non-Newtonian and is characterised by features such as shear rate-dependent
viscosities and non-zero normal stresses. This article begins with an
introduction to some unusual flow properties displayed by soft matter.
Experiments that report a spectrum of novel phenomena exhibited by these
materials, such as turbulent drag reduction, elastic turbulence, the formation
of shear bands and the existence of rheological chaos, flow-induced
birefringence and the unusual rheology of soft glassy materials, are reviewed.
The focus then shifts to observations of the liquid-like response of granular
media that have been subjected to external forces. The article concludes with
examples of the patterns that emerge when certain soft materials are vibrated,
or when they are displaced with Newtonian fluids of lower viscosities.


title: Finite volume treatment of $\pi\pi$ scattering in the $\rho$ channel

abstract:
  We make a theoretical study of $\pi\pi$ scattering with quantum numbers
$J^{PC}=1^{--}$ in a finite box. To calculate physical observables for infinite
volume from lattice QCD, the finite box dependence of the potentials is not
usually considered. We quantify such effects by means of two different
approaches for vector-isovector $\pi\pi$ scattering based on Unitarized Chiral
Perturbation Theory results: the Inverse Amplitude Method and another one based
on the $N/D$ method. We take into account finite box effects stemming from
higher orders through loops in the crossed $t,u-$channels as well as from the
renormalization of the coupling constants. The main conclusion is that for
$\pi\pi$ phase shifts in the isovector channel one can safely apply L\"uscher
based methods for finite box sizes of $L$ greater than $2 m_\pi^{-1}$.


title:
Repr\'esentations galoisiennes automorphes et cons\'equences
  arithm\'etiques des conjectures de Langlands et Arthur

abstract:
  This is the memoir of my habilitation thesis, defended on March 29 th, 2013
(Universit\'e Paris XI).


title: Star Formation in Nearby Isolated Galaxies

abstract:
  We use the FUV fluxes measured with the GALEX to study the star formation
properties of galaxies collected in the "Local Orphan Galaxies" catalog (LOG).
Among 517 LOG galaxies having radial velocities V(LG) < 3500 km/s and Galactic
latitudes |b|> 15 degr, 428 objects have been detected in FUV. We briefly
discuss some scaling relations between the specific star formation rate (SSFR)
and stellar mass, HI-mass, morphology, and surface brightness of galaxies
situated in extremely low density regions of the Local Supercluster. Our sample
is populated with predominantly late-type, gas-rich objects with the median
morphological type of Sdm. Only 5% of LOG galaxies are classified as early
types: E, S0, S0/a, however, they systematically differ from normal E and S0
galaxies by lower luminosity and presence of gas and dust. We find that almost
all galaxies in our sample have their SSFR below 0.4 [Gyr^{-1}]. This limit is
also true even for a sample of 260 active star-burst Markarian galaxies
situated in the same volume. The existence of such a quasi-Eddington limit for
galaxies seems to be a key factor which characterizes the transformation of gas
into stars at the current epoch.


title: Evidence for X(3872) from DD* scattering on the lattice

abstract:
  A candidate for the charmonium(like) state X(3872) is found 11 +/- 7 MeV
below the DD* threshold using dynamical Nf=2 lattice simulation with J^PC=1^++
and I=0. This is the first lattice simulation that establishes a candidate for
X(3872) in addition to the nearby scattering states D D* and J/psi omega, which
inevitably have to be present in dynamical QCD. We extract large and negative
DD* scattering length a_0=-1.7 +/- 0.4 fm and the effective range r_0=0.5 +/-
0.1 fm, but their reliable determination will have to wait for a simulation on
a larger volume. In I=1 channel, only the D D* and J/psi rho scattering states
are found and no candidate for X(3872). This is in agreement with the
interpretation that X(3872) is dominantly I=0, while its small I=1 component
arises solely from the isospin breaking and is therefore absent in our
simulation with m_u=m_d.


title: Probability functions in the context of signed involutive meadows

abstract:
  The Kolmogorov axioms for probability functions are placed in the context of
signed meadows. A completeness theorem is stated and proven for the resulting
equational theory of probability calculus. Elementary definitions of
probability theory are restated in this framework.


title: q-deformed Loewner evolution

abstract:
  The Loewner equation, in its stochastic incarnation introduced by Schramm, is
an insightful method for the description of critical random curves and
interfaces in two-dimensional statistical mechanics. Two features are crucial,
namely conformal invariance and a conformal version of the Markov property.
Extensions of the equation have been explored in various directions, in order
to expand the reach of such a powerful method. We propose a new generalization
based on q-calculus, a concept rooted in quantum geometry and non-extensive
thermodynamics; the main motivation is the explicit breaking of the Markov
property, while retaining scale invariance in the stochastic version. We focus
on the deterministic equation and give some exact solutions; the formalism
naturally gives rise to multiple mutually-intersecting curves. A general method
of simulation is constructed - which can be easily extended to other q-deformed
equations - and is applied to both the deterministic and the stochastic realms.
The way the $q\neq 1$ picture converges to the classical one is explored as
well.


title: Transverse spin diffusion in strongly interacting Fermi gases

abstract:
  We compute spin diffusion in a dilute Fermi gas at arbitrary temperature,
polarization and strong interaction in the normal phase using kinetic theory.
While the longitudinal spin diffusivity depends weakly on polarization and
diverges for small temperatures, the transverse spin diffusivity D_\perp has a
strong polarization dependence and approaches a finite value for T->0 in the
Fermi liquid phase. For a 3D unitary Fermi gas at infinite scattering length
the diffusivities reach a minimum near the quantum limit of diffusion \hbar/m
in the quantum degenerate regime and are strongly suppressed by medium
scattering, and we discuss the importance of the spin-rotation effect. In two
dimensions, D_\perp attains a minimum at strong coupling -1 < ln(kFa2D) < 1 and
reaches D_\perp~0.2...0.3\hbar/m at large polarization. These values are
consistent with recent measurements of two-dimensional ultracold atomic gases
in the strong coupling regime.


title:
Constraining Primordial Black-Hole Bombs through Spectral Distortions of
  the Cosmic Microwave Background

abstract:
  We consider the imprint of superradiant instabilities of nonevaporating
primordial black holes (PBHs) on the spectrum of the cosmic microwave
background (CMB). In the radiation dominated era, PBHs are surrounded by a
roughly homogeneous cosmic plasma which endows photons with an effective mass
through the plasma frequency. In this setting, spinning PBHs are unstable to a
spontaneous spindown through the well-known "black-hole bomb" mechanism. At
linear level, the photon density is trapped by the effective photon mass and
grows exponentially in time due to superradiance. As the plasma density
declines due to cosmic expansion, the associated energy around PBHs is released
and dissipated in the CMB. We evaluate the resulting spectral distortions of
the CMB in the redshift range 10^3 < z < 2x10^6. Using the existing COBE/FIRAS
bounds on CMB spectral distortions, we derive upper limits on the fraction of
dark matter that can be associated with spinning PBHs in the mass range
10^{-8}*Msun < M < 0.2*Msin. For maximally-spinning PBHs, our limits are much
tighter than those derived from microlensing or other methods. Future data from
the proposed PIXIE mission could improve our limits by several orders of
magnitude.


title:
Spectroscopy of proton-rich 66^Se up to J^{\pi} = 6^+: isospin-breaking
  effect in the A = 66 isobaric triplet

abstract:
  Candidates for three excited states in the 66^Se have been identified using
the recoil-{\beta} tagging method together with a veto detector for
charged-particle evaporation channels. These results allow a comparison of
mirror and triplet energy differences between analogue states across the A = 66
triplet as a function of angular momentum. The extracted triplet energy
differences follow the negative trend observed in the f_7/2 shell. Shell-model
calculations indicate a continued need for an additional isospin non-conserving
interaction in addition to the Coulomb isotensor part as a function of mass.


title: Single Transverse-Spin Asymmetries in Drell-Yan Processes

abstract:
  The asymmetry in the angular distribution of Drell--Yan dilepton pairs
generated in collisions where just one nucleon is transversely polarised has
been examined in the literature with a variety of results, mainly differing by
factors of two. We re-evaluate the asymmetry via twist-3 contributions in
collinear factorisation. In order to allow complete and in-depth comparison
with existing calculations, we supply all calculational details.


title: Dynamics of cancer recurrence

abstract:
  Mutation-induced drug resistance in cancer often causes the failure of
therapies and cancer recurrence, despite an initial tumor reduction. The timing
of such cancer recurrence is governed by a balance between several factors such
as initial tumor size, mutation rates and growth kinetics of drug-sensitive and
resistance cells. To study this phenomenon we characterize the dynamics of
escape from extinction of a subcritical branching process, where the
establishment of a clone of escape mutants can lead to total population growth
after the initial decline. We derive uniform in-time approximations for the
paths of the escape process and its components, in the limit as the initial
population size tends to infinity and the mutation rate tends to zero. In
addition, two stochastic times important in cancer recurrence will be
characterized: (i) the time at which the total population size first begins to
rebound (i.e., become supercritical) during treatment, and (ii) the first time
at which the resistant cell population begins to dominate the tumor.


title: Wulff shape of equilibrium crystals

abstract:
  The shape of an equilibrium crystal is obtained, according to the Gibbs
thermodynamic principle, by minimizing the total surface free energy associated
to the crystal-medium interface. To study the solution to this problem, known
as the Wulff construction, is the object of the article.


title: Photon correlations from ultra-strong optical nonlinearities

abstract:
  We study the full field and frequency filtered output photon statistics of a
resonator in thermal equilibrium with a bath and containing an arbitrarily
large quartic nonlinearity. According to the general theory of photodetection,
we derive general input-output relations valid for the ultra-anharmonic regime,
where the nonlinearity becomes comparable to the energy of the resonator, and
show how the emission properties are modified as compared to the generally
assumed simple anharmonic regime. We analyse the impact of the nonlinearity on
the full statistics of the emission and its spectral properties. In particular
we derive a semi-analytical expression for the frequency resolved two-photon
correlations or two-photon spectrum of the system in terms of the master
equation coefficients and density matrix. This provides a very clear insight
into the level structure and emission possibilities of the system.


title: Automated Small-Cell Deployment for Heterogeneous Cellular Networks

abstract:
  Optimizing the cellular network's cell locations is one of the most
fundamental problems of network design. The general objective is to provide the
desired Quality-of-Service (QoS) with the minimum system cost. In order to meet
a growing appetite for mobile data services, heterogeneous networks have been
proposed as a cost- and energy-efficient method of improving local spectral
efficiency. Whilst unarticulated cell deployments can lead to localized
improvements, there is a significant risk posed to network-wide performance due
to the additional interference.
  The first part of the paper focuses on state-of-the-art modelling and
radio-planning methods based on stochastic geometry and Monte-Carlo
simulations, and the emerging automatic deployment prediction technique for
low-power nodes (LPNs) in heterogeneous networks. The technique advises a LPN
where it should be deployed, given certain knowledge of the network. The second
part of the paper focuses on algorithms that utilize interference and physical
environment knowledge to assist LPN deployment. The proposed techniques can not
only improve network performance, but also reduce radio-planning complexity,
capital expenditure, and energy consumption of the cellular network. The
theoretical work is supported by numerical results from system-level
simulations that employ real cellular network data and physical environments.


title:
Critical behavior of nanocrystalline gadolinium: Evidence for a new
  universality class

abstract:
  We report on how nanocrystal size affects the critical behavior of the
rare-earth metal Gd near the ferromagnetic-to-paramagnetic phase transition.
The asymptotic critical behavior of the coarse-grained polycrystalline sample
(with an average crystallite size of $L \cong \unit[100]{\mu m}$) is that of a
(pure) \textsl{uniaxial dipolar} ferromagnet, as is the case with
single-crystal Gd, albeit the width of the asymptotic critical region (ACR) is
reduced. As the grain size approaches $\sim \unit[30]{nm}$, the ACR is so
narrow that it could not be accessed in the present experiments. Inaccessibly
narrow ACR for $L \sim \unit[30]{nm}$ and the continuous increase in the width
of ACR as $L$ decreases from $\unit[16]{nm}$ to $\unit[9.5]{nm}$ basically
reflects a crossover to the \textsl{random uniaxial dipolar} fixed point caused
by the quenched random-exchange disorder prevalent at the internal interfaces
(grain boundaries).


title:
Asymptotic equivalence of the discrete variational functional and a
  rate-large-deviation-like functional in the Wasserstein gradient flow of the
  porous medium equation

abstract:
  In this paper, we study the Wasserstein gradient flow structure of the porous
medium equation. We prove that, for the case of $q$-Gaussians on the real line,
the functional derived by the JKO-discretization scheme is asymptotically
equivalent to a rate-large-deviation-like functional. The result explains why
the Wasserstein metric as well as the combination of it with the
Tsallis-entropy play an important role.


title: Deformation of a magnetized neutron star

abstract:
  Magnetars are compact stars which are observationally determined to have very
strong surface magnetic fields of the order of $10^{14}-10^{15}$G. The centre
of the star can potentially have a magnetic field several orders of magnitude
larger. We study the effect of the field on the mass and shape of such a star.
In general, we assume a non-uniform magnetic field inside the star which varies
with density. The magnetic energy and pressure as well as the metric are
expanded as multipoles in spherical harmonics up to the quadrupole term.
Solving the Einstein equations for the gravitational potential, one obtains the
correction terms as functions of the magnetic field. Using a nonlinear model
for the hadronic EoS the excess mass and change in equatorial radius of the
star due to the magnetic field are quite significant if the surface field is
$10^{15}$G and the central field is about $10^{18}$ G. For a value of the
central magnetic field strength of $1.75\times10^{18}$ G, we find that both the
excess mass and the equatorial radius of the star changes by about $3-4\%$
compared to the spherical solution.


title: Coloring directed cycles

abstract:
  Sopena in his survey [E. Sopena, The oriented chromatic number of graphs: A
short survey, preprint 2013] writes, without any proof, that an oriented cycle
$\vec C$ can be colored with three colors if and only if $\lambda(\vec C)=0$,
where $\lambda(\vec C)$ is the number of forward arcs minus the number of
backward arcs in $\vec C$. This is not true. In this paper we show that $\vec
C$ can be colored with three colors if and only if $\lambda(\vec C)=0(\bmod~3)$
or $\vec C$ does not contain three consecutive arcs going in the same
direction.


title:
Quantum systems of ultra-cold bosons with customized inter-particle
  interactions

abstract:
  Recent progress in cooling and trapping of polarized clouds of chromium
$^{52}Cr$, dysprosium $^{164}Dy$ and erbium $^{168}Er$ opens a road-map to
quantum systems where shapes of inter-particle interactions can be customized.
The main purpose of this work is to get a deeper insight on a role which the
overall shape of the inter-particle interaction plays in a context of trapped
ultra-cold bosons. We show that strong inter-particle repulsion inevitably
leads to multi-hump fragmentation of the ground state. The fragmentation
phenomenon is universal -- it takes place in traps of different dimensionality
and topologies and for very broad classes of repulsive inter-particle
potentials. The physics behind is identified and explained.


title: Poly-Cauchy numbers and polynomials with umbral calculus viewpoint

abstract:
  In this paper, we give some interesting identities of poly-Cauchy numbers and
polynomials arising from umbral calculus.


title: Prediction in a non-homogeneous Poisson cluster model

abstract:
  A non-homogeneous Poisson cluster model is studied, motivated by insurance
applications. The Poisson center process which expresses arrival times of
claims, triggers off cluster member processes which correspond to number or
amount of payments. The cluster member process is an additive process. Given
the past observations of the process we consider expected values of future
increments and their mean squared errors, aiming the application in claims
reserving problems. Our proposed process can cope with non-homogeneous
observations such as the seasonality of claims arrival or the reducing property
of payment processes, which are unavailable in the former models where both
center and member processes are time homogeneous. Hence results presented in
this paper are significant extensions toward applications. We also give
numerical examples to show how non-homogeneity appears in predictions.


title: Electronic states in a graphene flake strained by a Gaussian bump

abstract:
  The effect of strain in graphene is usually modeled by a pseudo-magnetic
vector potential which is, however, derived in the limit of small strain. In
realistic cases deviations are expected in view of graphene's very high strain
tolerance, which can be up to 25%. Here we investigate the pseudo-magnetic
field generated by a Gaussian bump and we show that it exhibits significant
differences with numerical tight-binding results. Furthermore, we calculate the
electronic states in the strained region for a hexagon shaped flake with
armchair edges. We find that the six-fold symmetry of the wave functions inside
the Gaussian bump is directly related to the different effect of strain along
the fundamental directions of graphene: zigzag and armchair. Low energy
electrons are strongly confined in the armchair directions and are localized on
the carbon atoms of a single sublattice.


title: Prompt merger collapse and the maximum mass of neutron stars

abstract:
  We perform hydrodynamical simulations of neutron-star mergers for a large
sample of temperature-dependent, nuclear equations of state, and determine the
threshold mass above which the merger remnant promptly collapses to form a
black hole. We find that, depending on the equation of state, the threshold
mass is larger than the maximum mass of a non-rotating star in isolation by
between 30 and 70 per cent. Our simulations also show that the ratio between
the threshold mass and maximum mass is tightly correlated with the compactness
of the non-rotating maximum-mass configuration. We speculate on how this
relation can be used to derive constraints on neutron-star properties from
future observations.


title:
Geomagnetic Backtracing: A comparison of Tsyganenko 1996 and 2005
  External Field models with AMS-02 data

abstract:
  We used a backtracing code to reconstruct particle trajectory inside the
Earth Magnetosphere during the last solar active period (2011 and 2012) when
very high Solar Wind pressure values were measured. We compared our results on
AMS-02 proton and electron data with 2 different External Field models, namely
Tsyganenko 1996 (T96) and 2005 (T05), both for quiet (defined as the periods
when the solar wind pressure is below the average value, set at 2nPa) and
active periods. Although T05 has been specifically designed for storm events,
at high energy the particle trajectory is similar for the two models. For
instance at rigidities larger than 50 GV, the RMS of angular difference between
reconstructed asymptotic direction outside the Magnetosphere is of the order of
the millirad, while it increases at intermediate energies. We also confirmed,
as a function of the pointing direction, the well known East-West effect on the
trajectory of primary particles and on the access solid angle on the AMS
detector.


title: Stability, Higgs Boson Mass and New Physics

abstract:
  When the particle with mass $\sim 126$ GeV discovered at LHC is identified
with the Higgs boson of the Standard Model, intriguing and challenging
questions arise. Among them, the issue of the EW vacuum stability. We find
that, despite claims to the contrary, the latter strongly depends on new
physics interactions. In particular, if $\tau$ is the lifetime of the EW
vacuum, new physics can turn $\tau$ from $\tau >> T_U$ to $\tau << T_U$, where
$T_U$ is the age of the Universe.


title:
Developments for coating, testing, and aligning Cherenkov Telescope
  Array mirrors in T\"ubingen

abstract:
  The Cherenkov Telescope Array (CTA) is the next generation very-high energy
gamma-ray air-shower Cherenkov observatory. CTA will consist of many
segmented-mirror telescopes of three different diameters, placed in two arrays,
one in the Northern hemisphere and one in the South, thus covering the whole
sky. The total number of mirror tiles will be of the order of 10000,
corresponding to a reflective area of ~10^4 m^2. The Institute for Astronomy
and Astrophysics in T\"ubingen is developing procedures to coat
glass-substrate-based mirror tiles, is participating to the CTA mirror
prototype testing, and is prototyping Active Mirror Control alignment
mechanics, electronics and software. We will present the current status of our
work and plans for future developments.


title:
Suprathermal particle addition to solar wind pressure: possible
  influence on magnetospheric transmissivity of low energy cosmic rays?

abstract:
  Energetic (suprathermal) solar particles, accelerated in the interplanetary
medium, contribute to the solar wind pressure, in particular during high solar
activity periods. We estimated the effect of the increase of solar wind
pressure due to suprathermal particles on magnetospheric transmissivity of
galactic cosmic rays in the case of one recent solar event.

categories: astro-ph.IM astro-ph.EP astro-ph.SR physics.space-ph


title:
GeoMag and HelMod webmodels version for magnetosphere and heliosphere
  transport of cosmic rays

abstract:
  We implemented a website to deal with main effects on Cosmic Ray access to
the Earth, i.e. the Solar Modulation and the Geomagnetic Field effect. In
helmod.org the end user can easily access a web interface to results catalog of
the HelMod Monte Carlo Code. This Model uses a Monte Carlo Approach to solves
the Parker Transport Equation, obtaining a modulated proton flux for a period
(monthly average) between January 1990 and december 2007. geomagsphere.org is
instead based on GeoMag Backtracing Code, that solves the Lorentz equation with
a Runge-Kutta method of 6th order, and, reversing charge sign and velocity,
reconstruct particle trajectories in the Earth Magnetosphere back in time. We
use last models of internal (IGRF-11) and external (Tsyganenko 1996 -T96- and
2005 -T05-) field components valid up to 2015. Particles are backtraced to the
outer (magnetopause) or inner boundary to separate Primary (allowed trajectory)
from Secondary (forbidden) Cosmic Rays. This code has been used both for
reproducing known effects as East-West effect and rigidity cutoff calculations.
In geomagsphere.org the user can choose the external field model from
Tsyganenko (T96 or T05) and obtain for a fixed position and date from 1st Jan.
1968 (T96) and 1st Jan. 1995 (T05) respectively till 31$^{st}$ Dec 2012, the
vertical rigidity cutoff estimation obtained with the backtracing technique
with a rigidity step of 0.1 GV. For a more precise calculation (0.01 GV),
requiring more CPU time, results are sent to the user by email (mail model)


title: On the Contribution of Pulsars to the Positron Fraction in Cosmic Rays

abstract:
  Several cosmic ray experiments have measured the positron fraction up to few
hundred GeV. Their data have revealed an excess of positrons above 10 GeV that
is not consistent with the secondary production of these particles in the
interstellar medium. A primary source like dark matter or astrophysical sources
(e.g pulsars and their nebulae) were considered to account for such an excess.
In this paper we analyse the possibility of a primary positron production due
to pulsars. Under the assumption of equal initial spectra at the source for
positrons, electrons, and gamma-rays we study the propagation of particle
spectra using a diffusion model in the Galaxy. We focused our analysis on the
Vela and Crab pulsars and their associated nebulae, which are well observed in
gamma-rays. Comparison with experimental data is reported. The propagated
positron and electron spectra generated from these sources result in a positron
ratio, which is largely inconsistent with the excess observed by PAMELA and AMS


title: Pair plasma cushions in the hole-boring scenario

abstract:
  Pulses from a 10 PW laser are predicted to produce large numbers of
gamma-rays and electron-positron pairs on hitting a solid target. However, a
pair plasma, if it accumulates in front of the target, may partially shield it
from the pulse. Using stationary, one-dimensional solutions of the two-fluid
(electron-positron) and Maxwell equations, including a classical radiation
reaction term, we examine this effect in the hole-boring scenario. We find the
collective effects of a pair plasma "cushion" substantially reduce the
reflectivity, converting the absorbed flux into high-energy gamma-rays. There
is also a modest increase in the laser intensity needed to achieve threshold
for a non-linear pair cascade.


title:
Cosmic Ray Modulation studied with HelMod Monte Carlo tool and
  comparison with Ulysses Fast Scan Data during consecutive Solar Minima

abstract:
  The Cosmic Rays propagation was studied in details using the HelMod-2D Monte
Carlo code, that includes a general description of the diffusion tensor, and
polar magnetic-field. The Numerical Approach used in this work is based on a
set of Stochastic Differential Equations fully equivalent to the well know
Parker Equation for the transport of Cosmic Rays. In our approach the Diffusion
tensor in the frame of the magnetic field turbolence does not depends
explicitly by Solar Latitude but varies with time using a diffusion parameter
obtained by Neutron Monitors. The parameters of the Model were tuned using data
during the solar Cycle 23 and Ulysses latitudinal Fast Scan in 1995. The actual
parametrization is able to well reproduce the observed latitudinal gradient of
protons and the southward shift of the minimum of latitudinal intensity. The
description of the model is also available online at website www.helmod.org.
The model was then applied on Pamela/Ulysses proton intensity from 2006 up to
2009. The model during this 4-year continous period agree well with both PAMELA
(at 1 AU) and Ulysses data (at various solar distance and solar latitude). The
agreement improves when considering the ratio between this data. Studies done
also with particles with different charge (e.g. electrons) allow us to explain
the presence (or not) of protons and electrons latitudinal gradients observed
by Ulysses during the Latitudinal Fast Scan in 1995 and 2007.


title: Fokker-Planck equations for SPDE with non-trace class noise

abstract:
  In this paper we develop a new technique to prove existence of solutions of
Fokker-Planck equations on Hilbert spaces for Kolmogorov operators with non
trace-class second order coefficients or equivalently with an associated
stochastic partial differential equation (SPDE) with non trace-class noise.
Applications include stochastic 2D and 3D-Navier-Stokes equations with non
trace-class additive noise.


title: Ostrowski type inequalities for harmonically s-convex functions

abstract:
  The author introduces the concept of harmonically s-convex functions and
establishes some Ostrowski type inequalities and Hermite-Hadamard type
inequality of these classes of functions.


title: Muon reconstruction and identification with the Run II D0 detector

abstract:
  We present an overview of the muon reconstruction and identification methods
employed by the D0 Collaboration to analyze the Run II (2001-2011) ppbar data
of the Fermilab Tevatron collider at sqrt s = 1.96 TeV. We discuss the
performance of these methods, how it is measured using D0 data, and how it is
properly modeled by the D0 simulation program. In its pseudorapidity
acceptance, eta< 2, the muon system identifies high-pT muons (pT>10 GeV) with
efficiencies ranging from 72% to 89%. Muons tracks are reconstructed in the D0
central tracking system with efficiencies ranging from 85% to 92% and with a
typical relative momentum resolution of 10% for pT = 40 GeV. Isolation criteria
reject multijet background with efficiencies of 87% to 99%.


title: Existence problem of extremal Kaehler metrics

abstract:
  In this paper, we shall give some affirmative answer to an extremal Kaehler
version of the Yau-Tian-Donaldson Conjecture. For a polarized algebraic
manifold $(X,L)$, we choose a maximal algebraic torus $T$ in the group of
holomorphic automorphisms of $X$. Then the polarization class $c_1(L)$ will be
shown to admit an extremal Kaehler metric if $(X,L)$ is strongly K-stable
relative to $T$.


title: Calibration of the ASTRI SST-2M Prototype using Muon Ring Images

abstract:
  The study of ring images generated from high-energy muons is a very useful
tool for the performance monitoring and calibration of any Imaging Atmosphere
Cherenkov Telescope. Isolated muons travelling towards the telescope light
collector system produce characteristic Cherenkov ring images in the focal
plane camera. Since the geometry and the distribution of light deployed onto
the camera can be easily reconstructed analytically for a muon of given energy
and direction, muon rings are a powerful tool for monitoring the behaviour of
crucial properties of an imaging telescope such as the point-spread-function
and the overall light collection efficiency. In this contribution we present
the possibility of using the analysis of muon ring images as calibrator for the
ASTRI SST-2M prototype point spread function.


title: The post-Higgs MSSM scenario: Habemus MSSM?

abstract:
  We analyze the Minimal Supersymmetric extension of the Standard Model that we
have after the discovery of the Higgs boson at the LHC, the hMSSM (habemus
MSSM?), i.e. a model in which the lighter $h$ boson has a mass of approximately
125 GeV which, together with the non-observation of superparticles at the LHC,
indicates that the SUSY-breaking scale $M_S$ is rather high, $M_S > 1$ TeV. We
first demonstrate that the value $M_h \approx 125$ GeV fixes the dominant
radiative corrections that enter the MSSM Higgs boson masses, leading to a
Higgs sector that can be described, to a good approximation, by only two free
parameters. In a second step, we consider the direct supersymmetric radiative
corrections and show that, to a good approximation, the phenomenology of the
lighter Higgs state can be described by its mass and three couplings: those to
massive gauge bosons and to top and bottom quarks. We perform a fit of these
couplings using the latest LHC data on the production and decay rates of the
light $h$ boson and combine it with the limits from the negative search of the
heavier $H,A$ and $H^\pm$ states, taking into account the current
uncertainties.


title:
Stimulated and spontaneous four-wave mixing in silicon-on-insulator
  coupled photonic wire nano-cavities

abstract:
  We report on four-wave mixing in coupled photonic crystal nano-cavities on a
silicon-on-insulator platform. Three photonic wire cavities are side-coupled to
obtain three modes equally separated in energy. The structure is designed to be
self-filtering, and we show that the pump is rejected by almost two orders of
magnitudes. We study both the stimulated and the spontaneous four-wave mixing
processes: owing to the small modal volume, we find that signal and idler
photons are generated with a hundred-fold increase in efficiency as compared to
silicon micro-ring resonators.