title: Modulational instability and variational structure

abstract:
  We study the modulational instability of periodic traveling waves for a class
of Hamiltonian systems in one spatial dimension. We examine how the Jordan
block structure of the associated linearized operator bifurcates for small
values of the Floquet exponent to derive a criterion governing instability to
long wavelengths perturbations in terms of the kinetic and potential energies,
the momentum, the mass of the underlying wave, and their derivatives. The
dispersion operator of the equation is allowed to be nonlocal, for which Evans
function techniques may not be applicable. We illustrate the results by
discussing analytically and numerically equations of Korteweg-de Vries type.


title:
Banach spaces whose algebra of bounded operators has the integers as
  their $K_0$-group

abstract:
  Let $X$ and $Y$ be Banach spaces such that the ideal of operators which
factor through $Y$ has codimension one in the Banach algebra $\mathscr{B}(X)$
of all bounded operators on $X$, and suppose that $Y$ contains a complemented
subspace which is isomorphic to $Y\oplus Y$ and that $X$ is isomorphic to
$X\oplus Z$ for every complemented subspace $Z$ of $Y$. Then the $K_0$-group of
$\mathscr{B}(X)$ is isomorphic to the additive group $\mathbb{Z}$ of integers.
  A number of Banach spaces which satisfy the above conditions are identified.
Notably, it follows that $K_0(\mathscr{B}(C([0,\omega_1])))\cong\mathbb{Z}$,
where $C([0,\omega_1])$ denotes the Banach space of scalar-valued, continuous
functions defined on the compact Hausdorff space of ordinals not exceeding the
first uncountable ordinal $\omega_1$, endowed with the order topology.


title: Joint optimization of fitting & matching in multi-view reconstruction

abstract:
  Many standard approaches for geometric model fitting are based on pre-matched
image features. Typically, such pre-matching uses only feature appearances
(e.g. SIFT) and a large number of non-unique features must be discarded in
order to control the false positive rate. In contrast, we solve feature
matching and multi-model fitting problems in a joint optimization framework.
This paper proposes several fit-&-match energy formulations based on a
generalization of the assignment problem. We developed an efficient solver
based on min-cost-max-flow algorithm that finds near optimal solutions. Our
approach significantly increases the number of detected matches. In practice,
energy-based joint fitting & matching allows to increase the distance between
view-points previously restricted by robustness of local SIFT-matching and to
improve the model fitting accuracy when compared to state-of-the-art
multi-model fitting techniques.


title: R\'edei symbols and arithmetical mild pro-2-groups

abstract:
  Generalizing results of Morishita and Vogel, an explicit description of the
triple Massey product for the Galois group $G_S(2)$ of the maximal 2-extension
of $\mathbb{Q}$ unramified outside a finite set of prime numbers $S$ containing
2 is given in terms of R\'edei symbols. We show that mild pro-2-groups with
Zassenhaus invariant 3 occur as Galois groups of the form $G_S(2)$.
Furthermore, a non-analytic mild fab pro-2-group having only 3 generators is
constructed .


title:
Stellar Mass and color dependence of the three-point correlation
  function of galaxies in the local universe

abstract:
  The three-point correlation function (3PCF) for galaxies provides an
opportunity to measure the non-Gaussianity generated from nonlinear structure
formation and also probes information about galaxy formation and evolution that
is generally not available from the two-point correlation function (2PCF). We
measure the 3PCF of the Sloan Digital Sky Survey DR7 main sample galaxies in
both redshift and projected spaces on scales up to 40Mpc/h. We explore the
dependence of the 3PCF on galaxy stellar mass and color in order to constrain
the formation and evolution for galaxies of different properties. The study of
the dependence on these properties also helps better constrain the relation
between galaxy stellar mass and color and the properties of their hosting
dark-matter halos. We focus on the study of the reduced 3PCF, Q, defined as the
ratio between the 3PCF and the sum of the products of the 2PCFs. We find a very
weak stellar mass dependence of Q in both redshift and projected spaces. On
small scales, more massive galaxies tend to have slightly higher amplitudes of
Q. The shape dependence of Q is also weak on these small scales, regardless of
stellar mass and color. The reduced 3PCF has a strong color dependence for the
low-mass galaxies, while no significant dependence on color is found for the
high-mass galaxies. Low-mass red galaxies have higher amplitudes and stronger
shape dependence of the reduced 3PCF than the blue galaxies, implying that
these low-mass red galaxies tend to populate filamentary structures. The linear
galaxy bias model fails to interpret the color dependence of Q, emphasizing the
importance of a nonvanishing quadratic bias parameter in the correct modeling
of the galaxy color distribution.


title: Kernel Sparse Models for Automated Tumor Segmentation

abstract:
  In this paper, we propose sparse coding-based approaches for segmentation of
tumor regions from MR images. Sparse coding with data-adapted dictionaries has
been successfully employed in several image recovery and vision problems. The
proposed approaches obtain sparse codes for each pixel in brain magnetic
resonance images considering their intensity values and location information.
Since it is trivial to obtain pixel-wise sparse codes, and combining multiple
features in the sparse coding setup is not straightforward, we propose to
perform sparse coding in a high-dimensional feature space where non-linear
similarities can be effectively modeled. We use the training data from
expert-segmented images to obtain kernel dictionaries with the kernel K-lines
clustering procedure. For a test image, sparse codes are computed with these
kernel dictionaries, and they are used to identify the tumor regions. This
approach is completely automated, and does not require user intervention to
initialize the tumor regions in a test image. Furthermore, a low complexity
segmentation approach based on kernel sparse codes, which allows the user to
initialize the tumor region, is also presented. Results obtained with both the
proposed approaches are validated against manual segmentation by an expert
radiologist, and the proposed methods lead to accurate tumor identification.


title:
Strong solutions to stochastic differential equations with rough
  coefficients

abstract:
  We study strong existence and pathwise uniqueness for stochastic differential
equations in $\RR^d$ with rough coefficients, and without assuming uniform
ellipticity for the diffusion matrix. Our approach relies on direct
quantitative estimates on solutions to the SDE, assuming Sobolev bounds on the
drift and diffusion coefficients, and $L^p$ bounds for the solution of the
corresponding Fokker-Planck PDE, which can be proved separately. This allows a
great flexibility regarding the method employed to obtain these last bounds.
Hence we are able to obtain general criteria in various cases, including the
uniformly elliptic case in any dimension, the one-dimensional case and the
Langevin (kinetic) case.


title:
Quasithermal Neutrinos from Rotating Protoneutron Stars Born during Core
  Collapse of Massive Stars

abstract:
  Rotating and magnetized protoneutron stars (PNSs) may drive relativistic
magneto-centrifugally accelerated winds as they cool immediately after core
collapse. The wind fluid near the star is composed of neutrons and protons, and
the neutrons become relativistic while collisionally coupled with the ions.
Here, we argue that the neutrons in the flow eventually undergo inelastic
collisions around the termination shock inside the stellar material, producing
~0.1-1 GeV neutrinos, without relying on cosmic-ray acceleration mechanisms.
Even higher-energy neutrinos may be produced via particle acceleration
mechanisms. We show that PINGU and Hyper-Kamiokande can detect such neutrinos
from nearby core-collapse supernovae, by reducing the atmospheric neutrino
background via coincident detection of MeV neutrinos or gravitational waves and
optical observations. Detection of these GeV and/or higher-energy neutrinos
would provide important clues to the physics of magnetic acceleration,
nucleosynthesis, the relation between supernovae and gamma-ray bursts, and the
properties of newly born neutron stars.


title:
Correlated magnetic noise in global networks of gravitational-wave
  interferometers: observations and implications

abstract:
  One of the most ambitious goals of gravitational-wave astronomy is to observe
the stochastic gravitational-wave background. Correlated noise in two or more
detectors can introduce a systematic error, which limits the sensitivity of
stochastic searches. We report on measurements of correlated magnetic noise
from Schumann resonances at the widely separated LIGO and Virgo detectors. We
investigate the effect of this noise on a global network of interferometers and
derive a constraint on the allowable coupling of environmental magnetic fields
to test mass motion in gravitational-wave detectors. We find that while
correlated noise from global electromagnetic fields could be safely ignored for
initial LIGO stochastic searches, it could severely impact Advanced LIGO and
third-generation detectors.


title:
Search for direct CP violation in D0 -> h- h+ modes using semileptonic B
  decays

abstract:
  A search for direct CP violation in D0 -> h- h+ (where h=K or pi) is
presented using data corresponding to an integrated luminosity of 1.0 fb^-1
collected in 2011 by LHCb in pp collisions at a centre-of-mass energy of 7 TeV.
The analysis uses D0 mesons produced in inclusive semileptonic b-hadron decays
to the D0 mu X final state, where the charge of the accompanying muon is used
to tag the flavour of the D0 meson. The difference in the CP-violating
asymmetries between the two decay channels is measured to be
  Delta A_CP = A_CP(K-K+) - A_CP(pi-pi+) = (0.49 +- 0.30 (stat) +- 0.14 (syst))
% .
  This result does not confirm the evidence for direct CP violation in the
charm sector reported in other analyses.


title:
Cross sections for the $\gamma p \to K^{*+} \Lambda$ and $\gamma p \to
  K^{*+} \Sigma^{0}$ reactions measured at CLAS

abstract:
  The first high-statistics cross sections for the reactions $\gamma p \to
K^{*+} \Lambda$ and $\gamma p \to K^{*+} \Sigma^0$ were measured using the CLAS
detector at photon energies between threshold and 3.9 GeV at the Thomas
Jefferson National Accelerator Facility. Differential cross sections are
presented over the full range of the center-of-mass angles,
$\theta^{CM}_{K^{*+}}$, and then fitted to Legendre polynomials to extract the
total cross section. Results for the $K^{*+}\Lambda$ final state are compared
with two different calculations in an isobar and a Regge model, respectively.
Theoretical calculations significantly underestimate the $K^{*+} \Lambda$ total
cross sections between 2.1 and 2.6 GeV, but are in better agreement with
present data at higher photon energies.


title: Constraining Monodromy Inflation

abstract:
  We use cosmic microwave background (CMB) data from the 9-year WMAP release to
derive constraints on monodromy inflation, which is characterized by a linear
inflaton potential with a periodic modulation. We identify two possible
periodic modulations that significantly improve the fit, but it is unclear
whether this improvement is associated with a "signal" or with the scatter in
the measured angular power spectrum. The unmodulated potential is mildly
favored by standard model selection criteria. A modulated inflationary
potential can generate substantial primordial non-Gaussianity, of a specific
and characteristic form. For the best-fit parameters to the WMAP angular power
spectrum, the corresponding non-Gaussianity might be detectable in upcoming CMB
data, allowing nontrivial consistency checks on the predictions of a modulated
inflationary potential.


title: Study of two-neutron radioactivity in the decay of 26O

abstract:
  A new technique was developed to measure the lifetimes of neutron unbound
nuclei in the picosecond range. The decay of 26O -> 24O+n+n was examined as it
had been predicted to have an appreciable lifetime due to the unique structure
of the neutron-rich oxygen isotopes. The half-life of 26O was extracted as
4.5^{+1.1}_{-1.5}(stat.) +/- 3 (sys.) ps. This corresponds to 26O having a
finite lifetime at an 82% confidence level and, thus, suggests the possibility
of two-neutron radioactivity.


title:
DBI Galileon in the Effective Field Theory of Inflation: Orthogonal
  non-Gaussianities and constraints from the Trispectrum

abstract:
  Very few explicit inflationary scenarios are known to generate a large
bispectrum of orthogonal shape. Dirac-Born-Infeld Galileon inflation, in which
an induced gravity term is added to the DBI action, is one such model. We
formulate it in the language of the effective field theory of inflation by
identifying the unitary gauge operators that govern the behavior of its
cosmological fluctuations. We show how to recover rather easily from this its
power spectrum and bispectrum, which we calculated previously using standard
cosmological perturbation theory. We push our calculations up to the
determination of the fourth-order action and of the trispectrum, in which
shapes absent in k-inflation arise due to the presence of higher-order
derivative operators. We finally discuss the combined constraints set on this
model by current observational bounds on the bispectrum and trispectrum.


title: Making Systems More Robust with Flexible RPC Lookup

abstract:
  Modern distributed systems use names everywhere. Lockservices such as Chubby
and ZooKeeper provide an effective mechanism for mapping from application names
to server instances, but proper usage of them requires a large amount of
error-prone boiler-plate code.
  Application programmers often try to write wrappers to abstract away this
logic, but it turns out there is a more general and easier way of handling the
issue. We show that by extending the existing name resolution capabilities of
RPC libraries, we can remove the need for such annoying boiler-plate code while
at the same time making our services more robust.


title:
Universal features of counting statistics of thermal and quantum phase
  slips in superconducting nanocircuits

abstract:
  We perform measurements of phase-slip-induced switching current events on
different types of superconducting weak links and systematically study
statistical properties of the switching current distributions. We employ two
types of devices in which a weak link is formed either by a superconducting
nanowire or by a graphene flake subject to proximity effect. We demonstrate
that, independently on the nature of the weak link, higher moments of the
distribution take universal values. In particular, the third moment (skewness)
of the distribution is close to -1 both in thermal and quantum regimes. The
fourth moment (kurtosis) also takes a universal value close to 5. The
discovered universality of skewness and kurtosis is confirmed by an analytical
model. Our numerical analysis shows that introduction of extraneous noise into
the system leads to significant deviations from the universal values. We
suggest to use the discovered universality of higher moments as a robust tool
for checking against undesirable effects on noise in various types of
measurements.


title:
The VIMOS Public Extragalactic Redshift Survey (VIPERS). A Support
  Vector Machine classification of galaxies, stars and AGNs

abstract:
  The aim of this work is to develop a comprehensive method for classifying
sources in large sky surveys and we apply the techniques to the VIMOS Public
Extragalactic Redshift Survey (VIPERS). Using the optical (u*, g', r', i') and
NIR data (z', Ks), we develop a classifier, based on broad-band photometry, for
identifying stars, AGNs and galaxies improving the purity of the VIPERS sample.
Support Vector Machine (SVM) supervised learning algorithms allow the automatic
classification of objects into two or more classes based on a multidimensional
parameter space. In this work, we tailored the SVM for classifying stars, AGNs
and galaxies, and applied this classification to the VIPERS data. We train the
SVM using spectroscopically confirmed sources from the VIPERS and VVDS surveys.
We tested two SVM classifiers and concluded that including NIR data can
significantly improve the efficiency of the classifier. The self-check of the
best optical + NIR classifier has shown a 97% accuracy in the classification of
galaxies, 97 for stars, and 95 for AGNs in the 5-dimensional colour space. In
the test on VIPERS sources with 99% redshift confidence, the classifier gives
an accuracy equal to 94% for galaxies, 93% for stars, and 82% for AGNs. The
method was applied to sources with low quality spectra to verify their
classification, and thus increasing the security of measurements for almost 4
900 objects. We conclude that the SVM algorithm trained on a carefully selected
sample of galaxies, AGNs, and stars outperforms simple colour-colour selection
methods, and can be regarded as a very efficient classification method
particularly suitable for modern large surveys.


title:
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Galaxy
  clustering and redshift-space distortions at z=0.8 in the first data release

abstract:
  We present in this paper the general real- and redshift-space clustering
properties of galaxies as measured in the first data release of the VIPERS
survey. VIPERS is a large redshift survey designed to probe the distant
Universe and its large-scale structure at 0.5 < z < 1.2. We describe in this
analysis the global properties of the sample and discuss the survey
completeness and associated corrections. This sample allows us to measure the
galaxy clustering with an unprecedented accuracy at these redshifts. From the
redshift-space distortions observed in the galaxy clustering pattern we provide
a first measurement of the growth rate of structure at z = 0.8: f\sigma_8 =
0.47 +/- 0.08. This is completely consistent with the predictions of standard
cosmological models based on Einstein gravity, although this measurement alone
does not discriminate between different gravity models.


title:
The VIMOS Public Extragalactic Redshift Survey (VIPERS). An
  unprecedented view of galaxies and large-scale structure at 0.5<z<1.2

abstract:
  We describe the construction and general features of VIPERS, the VIMOS Public
Extragalactic Redshift Survey. This `Large Programme' has been using the ESO
VLT with the aim of building a spectroscopic sample of ~100,000 galaxies with
i_{AB}<22.5 and 0.5<z<1.5. The survey covers a total area of ~24 deg^2 within
the CFHTLS-Wide W1 and W4 fields. VIPERS is designed to address a broad range
of problems in large-scale structure and galaxy evolution, thanks to a unique
combination of volume (~ 5 x 10^7 h^{-3} Mpc^3) and sampling rate (~ 40%),
comparable to state-of-the-art surveys of the local Universe, together with
extensive multi-band optical and near-infrared photometry. Here we present the
survey design, the selection of the source catalogue and the development of the
spectroscopic observations. We discuss in detail the overall selection function
that results from the combination of the different constituents of the project.
This includes the masks arising from the parent photometric sample and the
spectroscopic instrumental footprint, together with the weights needed to
account for the sampling and the success rates of the observations. Using the
catalogue of 53,608 galaxy redshifts composing the forthcoming VIPERS Public
Data Release 1 (PDR-1), we provide a first assessment of the quality of the
spectroscopic data. Benefiting from the combination of size and detailed
sampling of this dataset, we conclude by presenting a map showing in
unprecedented detail the large-scale distribution of galaxies between 5 and 8
billion years ago. [abridged]


title: Mechanism for Odd Parity Superconductivity in Iron-Based Superconductors

abstract:
  Under the assumption that superconducting pairing is driven by local d-p
hybridization, we show that the superconducting state in iron-based
superconductors is classified as an odd parity s-wave spin-singlet pairing
state in a single trilayer FeAs/Se, the building block of the materials. In a
low energy effective model with only d-orbitals in an iron square bipartite
lattice, the superconducting order parameter in this state is a combination of
a s-wave normal pairing between two sublattices and a s-wave $\eta$-pairing
within the sublattices. Parity conservation was violated in proposed
superconducting states in the past. The results demonstrate iron-based
superconductors being a new quantum state of matter and suggest that a
measurement of odd parity can establish fundamental principles related to high
temperature superconducting mechanism.


title:
Potential of a Linear Collider for Lepton Flavour Violation studies in
  the SUSY seesaw

abstract:
  We study the potential of an e+- e- Linear Collider for charged lepton
flavour violation studies in a supersymmetric framework where neutrino masses
and mixings are explained by a type-I seesaw. Focusing on e-mu flavour
transitions, we evaluate the background from standard model and supersymmetric
charged currents to the e mu + missing E_T signal. We study the energy
dependence of both signal and background, and the effect of beam polarisation
in increasing the signal over background significance. Finally, we consider the
mu- mu- + missing E_T final state in e- e- collisions that, despite being
signal suppressed by requiring two e-mu flavour transitions, is found to be a
clear signature of charged lepton flavour violation due to a very reduced
standard model background.


title: 3d & 5d gauge theory partition functions as q-deformed CFT correlators

abstract:
  3d N=2 partition functions on the squashed three-sphere and on the twisted
product S2xS1 have been shown to factorize into sums of squares of solid tori
partition functions, the so-called holomorphic blocks. The same set of
holomorphic blocks realizes squashed three-sphere and S2xS1 partition functions
but the two cases involve different inner products, the S-pairing and the
id-pairing respectively. We define a class of q-deformed CFT correlators where
conformal blocks are controlled by a deformation of Virasoro symmetry and are
paired by S-pairing and id-pairing respectively. Applying the bootstrap
approach to a class of degenerate correlators we are able to derive three-point
functions. We show that degenerate correlators can be mapped to 3d partition
functions while the crossing symmetry of CFT correlators corresponds to the
flop symmetry of 3d gauge theories. We explore how non-degenerate q-deformed
correlators are related to 5d partition functions. We argue that id-pairing
correlators are associated to the superconformal index on S4xS1 while S-pairing
three-point function factors capture the one-loop part of S5 partition
functions. This is consistent with the interpretation of S2xS1 and squashed
three-sphere gauge theories as codimension two defect theories inside S4xS1 and
S5 respectively.


title: Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy

abstract:
  We obtained spectra, in the wavelength range \lambda = 995 - 1769 nm, of all
four known planets orbiting the star HR 8799. Using the suite of
instrumentation known as Project 1640 on the Palomar 5-m Hale Telescope, we
acquired data at two epochs. This allowed for multiple imaging detections of
the companions and multiple extractions of low-resolution (R ~ 35) spectra.
Data reduction employed two different methods of speckle suppression and
spectrum extraction, both yielding results that agree. The spectra do not
directly correspond to those of any known objects, although similarities with L
and T-dwarfs are present, as well as some characteristics similar to planets
such as Saturn. We tentatively identify the presence of CH_4 along with NH_3
and/or C_2H_2, and possibly CO_2 or HCN in varying amounts in each component of
the system. Other studies suggested red colors for these faint companions, and
our data confirm those observations. Cloudy models, based on previous
photometric observations, may provide the best explanation for the new data
presented here. Notable in our data is that these presumably co-eval objects of
similar luminosity have significantly different spectra; the diversity of
planets may be greater than previously thought. The techniques and methods
employed in this paper represent a new capability to observe and rapidly
characterize exoplanetary systems in a routine manner over a broad range of
planet masses and separations. These are the first simultaneous spectroscopic
observations of multiple planets in a planetary system other than our own.


title: Non-Galilean response of Rashba coupled Fermi gases

abstract:
  We consider the effect of a momentum kick on the ground state of a
non-interacting two-dimensional Fermi gas subject to Rashba spin-orbit
coupling. Although the total momentum is a constant of motion, the gas does not
obey the rules of Galilean relativity. Upon imprinting a small overall velocity
to the non-interacting gas, we find that the Fermi sea is deformed in a
non-trivial way. We also consider a weakly repulsive Fermi gas, and find, from
its Hartree shift, that the total ground state of the system may change into a
deformed, finite momentum ground state as the repulsion is increased beyond a
critical value, without the need of any external Zeeman fields. We also discuss
possible experimental signatures of these effects.


title:
Fundamental stellar and accretion disc parameters of the eclipsing
  binary DQ Velorum

abstract:
  To add to the growing collection of well-studied double periodic variables
(DPVs) we have carried out the first spectroscopic and photometric analysis of
the eclipsing binary DQ Velorum to obtain its main physical stellar and orbital
parameters. Combining spectroscopic and photometric observations that cover
several orbital cycles allows us to estimate the stellar properties of the
binary components and the orbital parameters. We also searched for
circumstellar material around the more massive star. We separated DQ Velorum
composite spectra and measured radial velocities with an iterative method for
double spectroscopic binaries. We obtained the radial velocity curves and
calculated the spectroscopic mass ratio. We compared our single-lined spectra
with a grid of synthetic spectra and estimated the temperature of the stars. We
modeled the V-band light curve with a fitting method based on the simplex
algorithm, which includes an accretion disc. To constrain the main stellar
parameters we fixed the mass ratio and donor temperature to the values obtained
by our spectroscopic analysis. We obtain donor and gainer masses, the radii,
and temperatures for the stellar components. We find that DQ Vel is a
semi-detached system consisting of a B3V gainer and an A1III donor star plus an
extended accretion disc around the gainer. The disc is filling 89% of the
gainer Roche lobe and it has a concave shape that is thicker at its edge than
at its centre. We find a significant sub-orbital frequency of 0.19 d^{-1} in
the residuals of the V-band light curve, which we interpret as a pulsation of
an slowly pulsating B-type (SPB) of a gainer star. We also estimate the
distance to the binary (3.1 kpc) using the absolute radii, apparent magnitudes,
and effective temperatures of the components found in our study.


title: Two Compton-Thick Active Nuclei in Arp 220?

abstract:
  Narrow-band spectral imaging with sub-pixel resolution of the Chandra-ACIS
archival observation of the ULIRG merger Arp 220 strongly suggests two Compton
thick nuclei, spatially coincident with the infrared and radio emitting nuclear
clusters, and separated by 1" (~ 365 pc at a distance of 76 Mpc). These
previously undetected highly obscured AGNs - West (W) and East (E) - are
imaged, and separated from neighboring sources, in the 6-7 keV band, where the
Fe-K lines dominate the emission. The western nucleus is also detected at
energies above 7 keV. We estimate Fe-K equivalent width ~ 1 keV or possibly
greater for both sources, and observed 2-10 keV luminosities L_X < 3.2 x 10^40
erg/s (W) and <1.3 x 10^40 erg/s (E). From the observed Fe-K lines
luminosities{, and assuming on the basis of the XMM-Newton spectrum that 40% of
this may be from the 6.4 keV component, we evaluate 2-10 keV intrinsic
luminosities L_X ~ 1 x 10^42 erg/s (W) and L_X ~ 0.4 x 10^42 erg/s (E). The
inferred X-ray luminosity is at least a factor of 3 higher than that expected
from a pure starburst with the bolometric luminosity of Arp 220. For a typical
AGN SED the bolometric luminosities are 5.2 x 10^43 erg/s (W) and 2 x 10^42
erg/s (E).


title: Quantum filtering using POVM measurements

abstract:
  The objective of this work is to develop a recursive, discrete time quantum
filtering equation for a system that interacts with a probe, on which
measurements are performed according to the Positive Operator Valued Measures
(POVMs) framework. POVMs are the most general measurements one can make on a
quantum system and although in principle they can be reformulated as projective
measurements on larger spaces, for which filtering results exist, a direct
treatment of POVMs is more natural and can simplify the filter computations for
some applications. Hence we formalize the notion of strongly commuting (Davies)
instruments which allows one to develop joint measurement statistics for POVM
type measurements. This allows us to prove the existence of conditional POVMs,
which is essential for the development of a filtering equation. We demonstrate
that under generally satisfied assumptions, knowing the observed probe POVM
operator is sufficient to uniquely specify the quantum filtering evolution for
the system.


title: Supersymmetric gauge theory and the Yangian

abstract:
  This paper develops a new connection between supersymmetric gauge theories
and the Yangian. I show that a twisted, deformed version of the pure N=1
supersymmetric gauge theory is controlled by the Yangian, in the same way that
Chern-Simons theory is controlled by the quantum group. This result is used to
give an exact calculation, in perturbation theory, of the expectation value of
a certain net of n+m Wilson operators in the deformed N=1 gauge theory. This
expectation value coincides with the partition function of a spin-chain
integrable lattice model on an n-by-m doubly-periodic lattice.


title:
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Luminosity and
  stellar mass dependence of galaxy clustering at 0.5<z<1.1

abstract:
  We investigate the dependence of galaxy clustering on luminosity and stellar
mass in the redshift range 0.5<z<1.1, using the first ~55000 redshifts from the
VIMOS Public Extragalactic Redshift Survey (VIPERS). We measured the
redshift-space two-point correlation functions (2PCF), and the projected
correlation function, in samples covering different ranges of B-band absolute
magnitudes and stellar masses. We considered both threshold and binned galaxy
samples, with median B-band absolute magnitudes -21.6<MB-5log(h)<-19.5 and
median stellar masses 9.8<log(M*[Msun/h^2])<10.7. We assessed the real-space
clustering in the data from the projected correlation function, which we model
as a power law in the range 0.2<r_p[Mpc/h]<20. Finally, we estimated the galaxy
bias as a function of luminosity, stellar mass, and redshift, assuming a flat
LCDM model to derive the dark matter 2PCF. We provide the best-fit parameters
of the power-law model assumed for the real-space 2PCF -- the correlation
length and the slope -- as well as the linear bias parameter, as a function of
the B-band absolute magnitude, stellar mass, and redshift. We confirm and
provide the tightest constraints on the dependence of clustering on luminosity
at 0.5<z<1.1. We prove the complexity of comparing the clustering dependence on
stellar mass from samples that are originally flux-limited and discuss the
possible origin of the observed discrepancies. Overall, our measurements
provide stronger constraints on galaxy formation models, which are now required
to match, in addition to local observations, the clustering evolution measured
by VIPERS galaxies between z=0.5 and z=1.1 for a broad range of luminosities
and stellar masses.


title: Gravity dual of dynamically broken supersymmetry

abstract:
  We study a renormalization group flow of ABJM theory embedded into the warped
A_8 geometry and explore the dependence of the vacuum structure on the
parameters of the theory. This model has a product group gauge structure
U(N)xU(n+l) and comes equipped with discrete parameters N, l and k, a
continuous parameter b related to the ratio of the Yang-Mills coupling for the
two gauge groups, and one dimensionful parameter gYM^2 setting the overall
scale. A supersymmetric supergravity solution exists when Q=N-l(l-k)/2k-k/24 is
positive and is interpretable as a RG flow from a Yang-Mills like UV fixed
point to a superconformal IR fixed point with free energy of order Q^3/2. The
fate of the theory when Q is taken to be negative is less clear. We explore the
structure of the possible gravity solution for small negative Q by considering
the linearized gravitational back reaction from adding a small number of
anti-branes on the Q=0 background. Following the work of Bena, et.al., we find
that a sensible solution satisfying appropriate boundary conditions does not
appear to exist. This leaves the status of the RG flow for the Q<0 theories a
mystery. We offer the following speculative resolution to the puzzle: the -k/24
unit of charge induced by the curvature correction to supergravity should be
considered an allowed physical object, and one should be adding an anti brane
not to the Q=0 background but rather the Q=-k/24 background. Such a solution
has a repulson singularity, and gives rise to a picture of the vacuum
configuration where a cluster of anti-branes are floating around the repulson
singularity, but are stabilized from being pushed off to infinity by other
fluxes. Such a state is non-supersymmetric and appears to describe a vacuum
with dynamical breaking of supersymmetry. Based on these considerations, we
construct a phase diagram for this theory exhibiting various interesting
regions.


title: On the invariant measures for the Ostrovsky equation

abstract:
  In this paper, we construct invariant measures for the Ostrovsky equation
associated with conservation laws. On the other hand, we prove the local well-
posedness of the initial value problem for the periodic Ostrovsky equation with
initial data in $H^{s}(\mathbb{T})$ for $s>-1/2$.


title: Energy Cooperation in Energy Harvesting Communications

abstract:
  In energy harvesting communications, users transmit messages using energy
harvested from nature during the course of communication. With an optimum
transmit policy, the performance of the system depends only on the energy
arrival profiles. In this paper, we introduce the concept of energy
cooperation, where a user wirelessly transmits a portion of its energy to
another energy harvesting user. This enables shaping and optimization of the
energy arrivals at the energy-receiving node, and improves the overall system
performance, despite the loss incurred in energy transfer. We consider several
basic multi-user network structures with energy harvesting and wireless energy
transfer capabilities: relay channel, two-way channel and multiple access
channel. We determine energy management policies that maximize the system
throughput within a given duration using a Lagrangian formulation and the
resulting KKT optimality conditions. We develop a two-dimensional directional
water-filling algorithm which optimally controls the flow of harvested energy
in two dimensions: in time (from past to future) and among users (from
energy-transferring to energy-receiving) and show that a generalized version of
this algorithm achieves the boundary of the capacity region of the two-way
channel.


title:
Application of object-oriented programming in a time-dependent
  density-functional theory calculation of exciton binding energies

abstract:
  This paper discusses the benefits of object-oriented programming to
scientific computing, using our recent calculations of exciton binding energies
with time-dependent density-functional theory (arXiv: 1302.6972) as a case
study. We find that an object-oriented approach greatly facilitates the
development, the debugging, and the future extension of the code by promoting
code reusing. We show that parallelism is added easily in our code in a
object-oriented fashion with ScaLAPACK, Boost::MPI and OpenMP.


title:
Imaging of non tumorous and tumorous human brain tissue with full-field
  optical coherence tomography

abstract:
  A prospective study was performed on neurosurgical samples from 18 patients
to evaluate the use of Full-Field Optical Coherence Tomography (FF-OCT) in
brain tumor diagnosis. FF-OCT captures en face slices of tissue samples at
1\mum resolution in 3D with a typical 200\mum imaging depth. A 1cm2 specimen is
scanned at a single depth and processed in about 5 minutes. This rapid imaging
process is non-invasive and 30 requires neither contrast agent injection nor
tissue preparation, which makes it particularly well suited to medical imaging
applications. Temporal chronic epileptic parenchyma and brain tumors such as
meningiomas, low- grade and high-grade gliomas, and choroid plexus papilloma
were imaged. A subpopulation of neurons, myelin fibers and CNS vasculature were
clearly identified. Cortex could be discriminated from white matter, but
individual glial cells as astrocytes (normal or reactive) or oligodendrocytes
were not observable. This study reports for the first time on the feasibility
of using FF-OCT in a real-time manner as a label-free non-invasive imaging
technique in an intra-operative neurosurgical clinical setting to assess
tumorous glial and epileptic margins.


title: Photon mediated interaction between distant quantum dot circuits

abstract:
  Engineering the interaction between light and matter is an important goal in
the emerging field of quantum opto-electronics. Thanks to the use of cavity
quantum electrodynamics architectures, one can envision a fully hybrid
multiplexing of quantum conductors. Here, we use such an architecture to couple
two quantum dot circuits . Our quantum dots are separated by 200 times their
own size, with no direct tunnel and electrostatic couplings between them. We
demonstrate their interaction, mediated by the cavity photons. This could be
used to scale up quantum bit architectures based on quantum dot circuits or
simulate on-chip phonon-mediated interactions between strongly correlated
electrons.


title:
Grazing incidence fast atom diffraction for He atoms impinging on a
  Ag(110) surface

abstract:
  Experimental diffraction patterns produced by grazing scattering of fast
helium atoms from a Ag(110) surface are used as a sensitive tool to test both
the scattering and the potential models. To describe the elastic collision
process we employ the surface eikonal (SE) approximation, which is a
semi-classical method that includes the quantum interference between
contributions coming from different projectile paths. The projectile-surface
potential is derived from an accurate density-functional theory (DFT)
calculation that takes into account the three degrees of freedom of the
incident projectile. A fairly good agreement between theoretical and
experimental momentum distributions is found for incidence along different
low-indexed crystallographic directions.


title: Extreme wave runup on a vertical cliff

abstract:
  Wave impact and run-up onto vertical obstacles are among the most important
phenomena which must be taken into account in the design of coastal structures.
From linear wave theory, we know that the wave amplitude on a vertical wall is
twice the incident wave amplitude with weakly nonlinear theories bringing small
corrections to this result. In this present study, however, we show that
certain simple wave groups may produce much higher run-ups than previously
predicted, with particular incident wave frequencies resulting in run up
heights exceeding the initial wave amplitude by a factor of 5, suggesting that
the notion of the design wave used in coastal structure design may need to be
revisited. The results presented in this study can be considered as a note of
caution for practitioners, on one side, and as a challenging novel material for
theoreticians who work in the field of extreme wave - coastal structure
interaction.


title:
The Analysis of Long-Term Frequency and Damping Wandering in Buildings
  Using the Random Decrement Technique

abstract:
  The characterization and monitoring of buildings is an issue that has
attracted the interest of many sectors over the last two decades. With the
increasing use of permanent, continuous and real-time networks, ambient
vibrations can provide a simple tool for the identification of dynamic building
parameters. This study is focused on the long-term variation of frequency and
damping in several buildings, using the Random Decrement Technique (RDT). RDT
provides a fast, robust and accurate long-term analysis and improves the
reliability of frequency and damping measurements for structural health
monitoring. This reveals particularly useful information in finding out
precisely how far changes in modal parameters can be related to changes in
physical properties. This paper highlights the reversible changes of the
structure's dynamic parameters, correlated with external forces, such as
temperature and exposure to the sun. Contrasting behaviors are observed,
including correlation and anti-correlation with temperature variations.


title:
Revealing Cluster Structure of Graph by Path Following Replicator
  Dynamic

abstract:
  In this paper, we propose a path following replicator dynamic, and
investigate its potentials in uncovering the underlying cluster structure of a
graph. The proposed dynamic is a generalization of the discrete replicator
dynamic. The replicator dynamic has been successfully used to extract dense
clusters of graphs; however, it is often sensitive to the degree distribution
of a graph, and usually biased by vertices with large degrees, thus may fail to
detect the densest cluster. To overcome this problem, we introduce a dynamic
parameter, called path parameter, into the evolution process. The path
parameter can be interpreted as the maximal possible probability of a current
cluster containing a vertex, and it monotonically increases as evolution
process proceeds. By limiting the maximal probability, the phenomenon of some
vertices dominating the early stage of evolution process is suppressed, thus
making evolution process more robust. To solve the optimization problem with a
fixed path parameter, we propose an efficient fixed point algorithm. The time
complexity of the path following replicator dynamic is only linear in the
number of edges of a graph, thus it can analyze graphs with millions of
vertices and tens of millions of edges on a common PC in a few minutes.
Besides, it can be naturally generalized to hypergraph and graph with edges of
different orders. We apply it to four important problems: maximum clique
problem, densest k-subgraph problem, structure fitting, and discovery of
high-density regions. The extensive experimental results clearly demonstrate
its advantages, in terms of robustness, scalability and flexility.


title:
Cancellation of quantum anomalies and bosonization of three-dimensional
  time-reversal symmetric topological insulators

abstract:
  The strong time-reversal symmetric (TRS) topological insulator (TI) in three
space dimensions features gapless surface states in the form of massless Dirac
fermions. We study these surface states with the method of bosonization, and
find that the resulting bosonic theory has a topological contribution due to
the parity anomaly of the surface Dirac fermions. We argue that the presence of
a quantum anomaly is, in fact, the main reason for the existence of a surface
state, by the principle that anomalies of a surface and bulk must cancel.
Inspecting other classes of topological insulators, we argue that this
principle holds in general. Moving beyond purely topological considerations, we
incorporate the dynamics of the surface electron states into the bosonic
theory. Additionally, we discuss the thermodynamics of the bosonic theory and
propose a representation of the surface Dirac fermions in terms of the bosonic
fields.


title: Theta(13) and charged Lepton Flavor Violation in "warped" A(4) models

abstract:
  We recently proposed a spontaneous A$_{4}$ flavor symmetry breaking scheme
implemented in a warped extra dimensional setup to explain the observed pattern
of quark and lepton masses and mixings. The main features of this choice are
the explanation of fermion mass hierarchies by wave function overlaps, the
emergence of tribimaximal (TBM) neutrino mixing and zero quark mixing at the
leading order and the absence of tree-level gauge mediated flavor violation.
Quark mixing and deviations from TBM neutrino mixing are induced by the
presence of bulk A$_4$ flavons, which allow for "cross-brane" interactions and
a "cross-talk" between the quark and neutrino sectors. In this work, we study
the constraints associated with the recent measurements of $\theta_{13}\approx
9^\circ$ by RENO and Daya Bay, forcing every model that predicts TBM neutrino
mixing to account for the significant deviation of $\theta_{13}$ from 0, while
keeping the values of $\theta_{12}$ and $\theta_{23}$ close to their central
experimental values. We then proceed to study in detail the RS-A$_4$
contributions to $\mu\to e,3e$, generated at the tree level by virtue of
anomalous $Z$ couplings. These couplings arise from gauge and fermionic KK
mixing effects after electroweak symmetry breaking. Since the experimental
sensitivity for $BR(\mu\to e,3e)$ is expected to increase by five orders of
magnitude within the next decade, it is shown that the RS-A$_4$ lepton sector
can be significantly constrained. Finally, we show that when "cross-brane"
interactions are turned off, the $Z$ couplings are protected against all
anomalous contributions and a strong correlation between $\theta_{13}$ and the
deviation from maximality of $\theta_{23}$ is found.


title: Work Issues in Software Engineering

abstract:
  Using data from a web-based survey of software developers, the author
attempts to determine root causes of "death march" projects and excessive work
hours in the software industry in relation to company practices and management.
Special emphasis is placed on the factor of business/technical supervisor
background. An analysis of variance revealed significant differences between
these supervisor groups with regard to a "Pointy-Haired Boss" (PHB) sentiment
index. This difference, combined with correlations between the PHB index and
the endpoints of project failure and use of software engineering practices,
indicate some disparity in the suitability of businessbackground supervisors to
manage software development projects compared with their technical-background
counterparts. Other survey data points to improved project management skills as
the biggest necessity for supervisors in the business-background group.


title:
Magnetically-Driven Suppression of Nematic Order in an Iron-Based
  Superconductor

abstract:
  A theory of superconductivity in the iron-based materials requires an
understanding of the phase diagram of the normal state. In these compounds,
superconductivity emerges when stripe spin density wave (SDW) order is
suppressed by doping, pressure or atomic disorder. This magnetic order is often
pre-empted by nematic order, whose origin is yet to be resolved. One scenario
is that nematic order is driven by orbital ordering of the iron 3d-electrons
that triggers stripe SDW order. Another is that magnetic interactions produce a
spin-nematic phase, which then induces orbital order. In this article, we
report the observation by neutron powder diffraction of an additional four-
fold-symmetric phase in Ba1-xNaxFe2As2 close to the suppression of SDW order,
which is consistent with the predictions of magnetically-driven models of
nematic order.


title: Affine cones over smooth cubic surfaces

abstract:
  We show that affine cones over smooth cubic surfaces do not admit non-trivial
$\mathbb{G}_a$ -actions.


title:
A revised estimate of the occurrence rate of terrestrial planets in the
  habitable zones around kepler m-dwarfs

abstract:
  Because of their large numbers, low mass stars may be the most abundant
planet hosts in our Galaxy. Furthermore, terrestrial planets in the habitable
zones (HZs) around M-dwarfs can potentially be characterized in the near future
and hence may be the first such planets to be studied. Recently Dressing &
Charbonneau(2013) used Kepler data and calculated the frequency of terrestrial
planets in the HZ of cool stars to be 0.15^{+0.13}_{-0.06} per star for
Earth-size planets (0.5-1.4 R_{Earth}). However, this estimate was derived
using the Kasting et al.(1993) HZ limits, which were not valid for stars with
effective temperatures lower than 3700 K. Here we update their result using new
HZ limits from Kopparapu et al.(2013) for stars with effective temperatures
between 2600 K and 7200 K, which includes the cool M stars in the Kepler target
list. The new habitable zone boundaries increase the number of planet
candidates in the habitable zone. Assuming Earth-size planets as 0.5 - 1.4
R_{Earth}, when we reanalyze their results, we obtain a terrestrial planet
frequency of 0.48^{+0.12}_{-0.24} and 0.53^{+0.08}_{-0.17} planets per M-dwarf
star for conservative and optimistic limits of the HZ boundaries, respectively.
Assuming Earth-size planets as 0.5 - 2 R_{Earth}, the frequency increases to
0.51^{+0.10}_{-0.20} per star for the conservative estimate and to
0.61^{+0.07}_{-0.15} per star for the optimistic estimate. Within
uncertainties, our optimistic estimates are in agreement with a similar
optimistic estimate from the radial velocity survey of M-dwarfs
(0.41^{+0.54}_{-0.13}, Bonfils et al.(2011)). So, the potential for finding
Earth-like planets around M stars may be higher than previously reported.


title: Diffusion on hierarchical systems of weakly-coupled networks

abstract:
  We analyse diffusion dynamics on weakly-coupled networks (interconnected
networks) by means of separation of time scales. Using an adiabatic
approximation we reduced the system dynamics to a Markov chain with aggregated
variables and derived a transport equation that is analogous to Fick's First
Law and includes a driving force. Entropy production is a sum of microscopic
entropy transport, which results from the particle's migration between networks
of different topologies and macroscopic entropy production of the Markov chain.
Equilibrium particles partition between different sub-networks depends only on
internal sub-network parameters. Our framework, confirmed by numerical
simulations, is also useful for considering diffusion in nested systems
corresponding to hierarchical networks with several different time scales thus
it can serve to uncover hidden hierarchy levels from observations of diffusion
processes.


title: Hybrid Q-Learning Applied to Ubiquitous recommender system

abstract:
  Ubiquitous information access becomes more and more important nowadays and
research is aimed at making it adapted to users. Our work consists in applying
machine learning techniques in order to bring a solution to some of the
problems concerning the acceptance of the system by users. To achieve this, we
propose a fundamental shift in terms of how we model the learning of
recommender system: inspired by models of human reasoning developed in robotic,
we combine reinforcement learning and case-base reasoning to define a
recommendation process that uses these two approaches for generating
recommendations on different context dimensions (social, temporal, geographic).
We describe an implementation of the recommender system based on this
framework. We also present preliminary results from experiments with the system
and show how our approach increases the recommendation quality.


title:
Existence and merging of Dirac points in $\alpha$-(BEDT-TTF)$_2$I$_3$
  organic conductor

abstract:
  We reexamine the existence and stability conditions of Dirac points between
valence and conduction bands of 3/4 filled $\alpha$-(BEDT-TTF)$_2$I$_3$
conducting plane. We consider the usual nearest neigbhor tight binding model
with the seven transfer energies that depend on the applied pressure. Owing to
the four distinct molecules (A, A', B, C) per unit cell of the Bravais lattice,
the corresponding Bloch Hamiltonian is a $4\times4$ matrix ${\cal H}({\bm k})$
for each wave vector $\mathbf{k}$ of the Brillouin zone. In most previous works
the study of Dirac points was achieved through direct numerical diagonalization
of matrix ${\cal H}({\bm k})$. In this work we develop a novel analytical
approach which allows to analyze the existence and stability conditions of
Dirac points from the knowledge of their merging properties at time reversal
points. Within this approach we can discuss thoroughly the role of each
transfer integrals and demonstrate that inversion symmetry is convenient but
not necessary.


title: Lattice Boltzmann based discrete simulation for gas-solid fluidization

abstract:
  Discrete particle simulation, a combined approach of computational fluid
dynamics and discrete methods such as DEM (Discrete Element Method), DSMC
(Direct Simulation Monte Carlo), SPH (Smoothed Particle Hydrodynamics), PIC
(Particle-In-Cell), etc., is becoming a practical tool for exploring lab-scale
gas-solid systems owing to the fast development of parallel computation.
However, gas-solid coupling and the corresponding fluid flow solver remain
immature. In this work, we propose a modified lattice Boltzmann approach to
consider the effect of both the local solid volume fraction and the local
relative velocity between particles and fluid, which is different from the
traditional volume-averaged Navier-Stokes equations. A time-driven hard sphere
algorithm is combined to simulate the motion of individual particles, in which
particles interact with each other via hard-sphere collisions, the collision
detection and motion of particles are performed at constant time intervals. The
EMMS (energy minimization multi-scale) drag is coupled with the lattice
Boltzmann based discrete particle simulation to improve the accuracy. Two
typical fluidization processes, namely, a single bubble injection at incipient
fluidization and particle clustering in a fast fluidized bed riser, are
simulated with this approach, with the results showing a good agreement with
published correlations and experimental data. The capability of the approach to
capture more detailed and intrinsic characteristics of particle-fluid systems
is demonstrated. The method can also be used straightforward with other solid
phase solvers.


title: Secure Wireless Communications via Cooperative Transmitting

abstract:
  Information theoretic secrecy is combined with cryptographic secrecy to
create a secret-key exchange protocol for wireless networks. A network of
transmitters, which already have cryptographically secured channels between
them, cooperate to exchange a secret key with a new receiver at a random
location, in the presence of passive eavesdroppers at unknown locations. Two
spatial point processes: homogeneous Poisson process and independent uniformly
distributed points are used for the spatial distributions of transmitters and
eavesdroppers. We analyse the impact of the number of cooperating transmitters
and the number of eavesdroppers on the area fraction where secure communication
is possible. Upper bounds on the probability of existence of positive secrecy
between the cooperating transmitters and the receiver are derived. The
closeness of the upper bounds to the real value is then estimated by means of
numerical simulations. Simulations also indicate that a deterministic spatial
distribution for the transmitters e.g. hexagonal and square lattices, increases
the probability of existence of positive secrecy capacity compared to the
random spatial distributions. For the same number of friendly nodes,
cooperative transmitting provides a dramatically larger secrecy region than
cooperative jamming and cooperative relaying.


title: Ice Lines in Circumbinary Protoplanetary Disks

abstract:
  I examine the position of the ice line in circumbinary disks heated by steady
mass accretion and stellar irradiation and compare with the critical semi-major
axis, interior to which planetary orbits are unstable. There is a critical
binary separation, dependent on the binary parameters and disk properties, for
which the ice line lies within the critical semi-major axis for a given binary
system. For an equal mass binary comprised of 1 M$_{\odot}$ components, this
critical separation is $\approx 1.04 $AU, and scales weakly with mass accretion
rate and Rosseland mean opacity ($\propto [\dot{M}\kappa_R]^{2/9}$). Assuming a
steady mass accretion rate of $\dot{M} \sim 10^{-8} {\rm M_{\odot} yr^{-1}}$
and a Rosseland mean opacity of $\kappa_R\sim 1 {\rm cm^2 g^{-1}}$, I show that
$\gtrsim 80%$ of all binary systems with total masses $M_{\rm tot} \lesssim 4.0
M_{\odot}$ have ice lines that lie interior to the critical semi-major axis.
This suggests that rocky planets should not form in these systems, a prediction
which can be tested by looking for planets around binaries with separations
larger than the critical separation with \emph{Kepler} (difficult) and with
microlensing.


title:
A new method for the extraction of mid-infrared gamma-ray emitting
  candidate blazars

abstract:
  We present a new method for identifying blazar candidates by examining the
locus, i.e. the region occupied by the Fermi gamma-ray blazars in the
three-dimensional color space defined by the WISE infrared colors. This method
is a refinement of our previous approach that made used of the two-dimensional
projection of the the distribution of WISE gamma-ray emitting blazars (the
Strip) in the three WISE color-color planes. In this paper, we define the
three-dimensional locus by means of a Principal Component analysis of the the
colors distribution of a large sample of blazars composed by all the ROMA-BZCAT
sources with counterparts in the WISE All-Sky Catalog and associated to a
gamma-ray source in the second Fermi LAT catalog (2FGL) (the WISE Fermi Blazars
sample, WFB). Our new procedure, as reported in [D'Abrusco et al. 2013], yields
a total completeness of c=81% and total efficiency of e=97%.


title:
Electronic spectral properties of the two-dimensional infinite-U Hubbard
  model

abstract:
  A strong-coupling series expansion for the Green's function and the
extremely-correlated Fermi liquid (ECFL) theory are used to calculate the
moments of the electronic spectral functions of the infinite-U Hubbard model.
Results from these two complementary methods agree very well at both, low
densities, where the ECFL solution is the most accurate, and at high to
intermediate temperatures, where the series converge. We find that a modified
first moment, which underestimates the contributions from the occupied states
and is accessible in the series through the time-dependent Green's function,
best describes the quasiparticle peak location in the strongly-correlated
regime. This is examined by the ECFL results at low temperatures, where it is
shown that the spectral function is largely skewed towards the occupied states.


title: Probing two approaches to Unified Dark Dynamics

abstract:
  Dark matter and dark energy are essential in the description of the late
Universe, since at least the epoch of equality. On the other hand, the
inflation is also necessary and demands a "dark" component, usually associated
to a scalar field that dominated the dynamics and kinematics in the very early
Universe. Yet, these three dark components of standard model of cosmology are
independent from each other, although there are alternative models that pursue
to achieve a triple unification, or at least a double. In the present work we
present an update of two models that we have considered in recent years. The
first is the "dark fluid" model in which dark matter and dark energy are the
same thing, achieving a double unification with specific properties that
exactly emulate the standard model of cosmology, given the dark degeneracy that
exists in the LCDM model. The second model is given by a single F(X) scalar
field Lagrangian, with which one is able to model the whole cosmological
dynamics, from inflation to today, representing a triple unification model. We
highlight the main properties of these models, as well as we test them against
known cosmological probes.


title: A Pilot for a VLA HI Deep Field

abstract:
  High-resolution 21-cm HI deep fields provide spatially and kinematically
resolved neutral gas maps at different redshifts, which are key to
understanding galaxy evolution across cosmic time and testing predictions of
cosmological simulations. Here we present results from a pilot for the COSMOS
HI Large Extragalactic Survey (CHILES) done with the Karl G. Jansky Very Large
Array (VLA). We take advantage of the newly expanded capabilities of the
telescope to probe the redshift interval 0<z<0.193 in one observation. We
observe the COSMOS field for 50 hours, which contains 413 galaxies with optical
spectroscopic redshifts in the imaged field of view of 34' x 34' and the
observed redshift interval. We have detected neutral hydrogen gas in 33
galaxies in different environments spanning the probed redshift range,
including three without a previously known spectroscopic redshift. The
detections have a range of HI and stellar masses, indicating the diversity of
galaxies we are probing. We discuss the observations, data reduction, results
and highlight interesting detections. We find that the VLA's B-array is the
ideal configuration for HI deep fields since its long spacings mitigate RFI.
This pilot shows that the VLA is ready to carry out such a survey, and serves
as a test for future HI deep fields planned with other SKA pathfinders.


title: Chiral Liouville Gravity

abstract:
  Classical two-dimensional Liouville gravity is often considered in conformal
gauge which has a residual left and right Virasoro symmetry algebra. We
consider an alternate, chiral, gauge which has a residual right Virasoro
Kac-Moody algebra, and no left Virasoro algebra. The Kac-Moody zero mode is the
left-moving energy. Dirac brackets of the constrained Hamiltonian theory are
derived, and the residual symmetries are shown to be generated by integrals of
the conserved chiral currents. The central charge and Kac-Moody level are
computed. The possible existence of a corresponding quantum theory is
discussed.


title: Exploring 6D origins of 5D supergravities with Chern-Simons terms

abstract:
  We consider five-dimensional supergravity theories with eight or sixteen
supercharges with Abelian vector fields and ungauged scalars. We address the
question under which conditions these theories can be interpreted as effective
low energy descriptions of circle reductions of anomaly free six-dimensional
theories with (1,0) or (2,0) supersymmetry. We argue that classical and
one-loop gauge- and gravitational Chern-Simons terms are instrumental for this
question.


title: New Boundary Conditions for AdS3

abstract:
  New chiral boundary conditions are found for quantum gravity with matter on
AdS3. The associated asymptotic symmetry group is generated by a single
right-moving U(1) Kac-Moody-Virasoro algebra with c_R = 3l/2G. The Kac-Moody
zero mode generates global left-moving translations and equals, for a BTZ black
hole, the sum of the total mass and spin. The level is positive about the
global vacuum and negative in the black hole sector, corresponding to
ergosphere formation. Realizations arising in Chern-Simons gravity and string
theory are analyzed. The new boundary conditions are shown to naturally arise
for warped AdS3 in the limit that the warp parameter is taken to zero.


title: Spectral Clustering with Epidemic Diffusion

abstract:
  Spectral clustering is widely used to partition graphs into distinct modules
or communities. Existing methods for spectral clustering use the eigenvalues
and eigenvectors of the graph Laplacian, an operator that is closely associated
with random walks on graphs. We propose a new spectral partitioning method that
exploits the properties of epidemic diffusion. An epidemic is a dynamic process
that, unlike the random walk, simultaneously transitions to all the neighbors
of a given node. We show that the replicator, an operator describing epidemic
diffusion, is equivalent to the symmetric normalized Laplacian of a reweighted
graph with edges reweighted by the eigenvector centralities of their incident
nodes. Thus, more weight is given to edges connecting more central nodes. We
describe a method that partitions the nodes based on the componentwise ratio of
the replicator's second eigenvector to the first, and compare its performance
to traditional spectral clustering techniques on synthetic graphs with known
community structure. We demonstrate that the replicator gives preference to
dense, clique-like structures, enabling it to more effectively discover
communities that may be obscured by dense intercommunity linking.


title: Superbubble breakout and galactic winds from disk galaxies

abstract:
  We study the conditions for disk galaxies to produce superbubbles that can
break out of the disk and produce a galactic wind. We argue that the threshold
surface density of supernovae rate for seeding a wind depends on the ability of
superbubble energetics to compensate for radiative cooling. We first adapt
Kompaneets formalism for expanding bubbles in a stratified medium to the case
of continuous energy injection and include the effects of radiative cooling in
the shell. With the help of hydrodynamic simulations, we then study the
evolution of superbubbles evolving in stratified disks with typical disk
parameters. We identify two crucial energy injection rates that differ in their
effects, the corresponding breakout ranging from being gentle to a vigorous
one. (a) Superbubbles that break out of the disk with a Mach number of order
2-3 correspond to an energy injection rate of order 10^{-4} erg cm^{-2} s^{-1},
which is relevant for disk galaxies with synchrotron emitting gas in the
extra-planar regions. (b) A larger energy injection threshold, of order 10^{-3}
erg cm^{-2} s^{-1}, or equivalently, a star formation surface density of \sim
0.1 solar mass yr^{-1} kpc^{-2}, corresponds to superbubbles with a Mach number
\sim 5-10. While the milder superbubbles can be produced by large OB
associations, the latter kind requires super-starclusters. These derived
conditions compare well with observations of disk galaxies with winds and the
existence of multiphase halo gas. Furthermore, we find that contrary to the
general belief that superbubbles fragment through Rayleigh-Taylor (RT)
instability when they reach a vertical height of order the scale height, the
superbubbles are first affected by thermal instability for typical disk
parameters and that RT instability takes over when the shells reach a distance
of approximately twice the scale height.


title:
Black hole discharge in massive electrodynamics and black hole
  disappearance in massive gravity

abstract:
  We define and calculate the "discharge mode" for a Schwarzschild black hole
in massive electrodynamics. For small photon mass, the discharge mode describes
the decay of the electric field of a charged star collapsing into a black hole.
We argue that a similar "discharge of mass" occurs in massive gravity and leads
to a strange process of black hole disappearance.


title:
Constraining the astrophysical origin of the p-nuclei through nuclear
  physics and meteoritic data

abstract:
  A small number of naturally occurring, proton-rich nuclides (the p-nuclei)
cannot be made in the s- and r-process. Their origin is not well understood.
Massive stars can produce p-nuclei through photodisintegration of pre-existing
intermediate and heavy nuclei. This so-called gamma-process requires high
stellar plasma temperatures and occurs mainly in explosive O/Ne burning during
a core-collapse supernova. Although the gamma-process in massive stars has been
successful in producing a large range of p-nuclei, significant deficiences
remain. An increasing number of processes and sites has been studied in recent
years in search of viable alternatives replacing or supplementing the massive
star models. A large number of unstable nuclei, however, with only
theoretically predicted reaction rates are included in the reaction network and
thus the nuclear input may also bear considerable uncertainties. The current
status of astrophysical models, nuclear input, and observational constraints is
reviewed. After an overview of currently discussed models, the focus is on the
possibility to better constrain those models through different means.
Meteoritic data not only provide the actual isotopic abundances of the p-nuclei
but can also put constraints on the possible contribution of proton-rich
nucleosynthesis. The main part of the review focusses on the nuclear
uncertainties involved in the determination of the astrophysical reaction rates
required for the extended reaction networks used in nucleosynthesis studies.
Experimental approaches are discussed together with their necessary connection
to theory, which is especially pronounced for reactions with intermediate and
heavy nuclei in explosive nuclear burning, even close to stability.

categories: astro-ph.SR astro-ph.HE astro-ph.IM nucl-ex nucl-th


title: Mock Observations of Blue Stragglers in Globular Cluster Models

abstract:
  We created artificial color-magnitude diagrams of Monte Carlo dynamical
models of globular clusters, and then used observational methods to determine
the number of blue stragglers in those clusters. We compared these blue
stragglers to various cluster properties, mimicking work that has been done for
blue stragglers in Milky Way globular clusters to determine the dominant
formation mechanism(s) of this unusual stellar population. We find that a
mass-based prescription for selecting blue stragglers will choose approximately
twice as many blue stragglers than a selection criterion that was developed for
observations of real clusters. However, the two numbers of blue stragglers are
well-correlated, so either selection criterion can be used to characterize the
blue straggler population of a cluster. We confirm previous results that the
simplified prescription for the evolution of a collision or merger product in
the BSE code overestimates their lifetimes. We show that our model blue
stragglers follow similar trends with cluster properties (core mass, binary
fraction, total mass, collision rate) as the true Milky Way blue stragglers, as
long as we restrict ourselves to model clusters with an initial binary fraction
higher than 5%. We also show that, in contrast to earlier work, the number of
blue stragglers in the cluster core does have a weak dependence on the
collisional parameter Gamma in both our models and in Milky Way globular
clusters.


title:
Y-system for form factors at strong coupling in AdS5 and with
  multi-operator insertions in AdS3

abstract:
  We study form factors in N=4 SYM at strong coupling in general kinematics and
with multi-operator insertions by using gauge/string duality and integrability
techniques. This generalizes the AdS3 results of Maldacena and Zhiboedov in two
non-trivial aspects. The first generalization to AdS5 space was motivated by
its potential connection to strong coupling Higgs-to-three-gluons amplitudes in
QCD which was observed recently at weak coupling. The second generalization to
multi-operator insertions was motivated as a step towards applying on-shell
techniques to compute correlation functions at strong coupling. In this
picture, each operator is associated to a monodromy condition on the cusp
solutions. We construct Y-systems for both cases. The Y-functions are related
to the spacetime (cross) ratios. Their WKB approximations based on a rational
function P(z) are also studied. We focus on the short operators, while the
prescription is hopefully also applicable for more general operators.


title: Crawling scallop: Friction-based locomotion with one degree of freedom

abstract:
  Fluid-based locomotion at low Reynolds number is subject to the constraints
of the scallop theorem, which dictate that body kinematics identical under a
time-reversal symmetry (in particular, those with a single degree of freedom)
cannot display locomotion on average. The implications of the theorem naturally
compel one to ask whether similar symmetry constraints exist for locomotion in
different environments. In this work we consider locomotion along a surface
where forces are described by isotropic Coulomb friction. To address whether
motions with a single degree of freedom can lead to transport, we analyze a
model system consisting of two bodies whose separation distance undergoes
periodic time variations. The behavior of the two-body system is entirely
determined by the kinematic specification of their separation, the friction
forces, and the mass of each body. We show that the constraints of the scallop
theorem can be escaped in frictional media if two asymmetry conditions are met
at the same time: the frictional forces of each body against the surface must
be distinct and the time-variation of the body-body separation must vary
asymmetrically in time (so quick-slow or slow-quick in the
extension-contraction phases). Our results are demonstrated numerically and
interpreted using asymptotic expansions.


title: Constructing Strong Markov Processes

abstract:
  The construction presented in this paper can be briefly described as follows:
starting from any "finite-dimensional" Markov transition function p_t, on a
measurable state space (E,B), we construct a strong Markov process on a certain
"intrinsic" state space that is, in fact, a closed subset of a finite
dimensional Euclidean space R^d. Of course we must explain the meaning of
finite-dimensionality and intrinsity. Starting with p_t, we consider the range
of the nonnegative bounded measurable functions under the action of the
resolvent. This class of functions induces a uniform structure on E. We say
that E is finite-dimensional if this uniformity is finitely generated. In such
cases we then map E into R^d. The intrinsic state space is the closure of the
range of this mapping. On this enlarged state space we construct a strong
Markov process, which corresponds quite naturally to p_t. We give several
examples including the usual examples of nonstrong Markov process.


title:
Open Book Structures on Moment-Angle Manifolds $Z^{\mathbb C}(\Lambda)$
  and Higher Dimensional Contact Manifolds

abstract:
  We construct open book structures on moment-angle manifolds and give a new
construction of examples of contact manifolds in arbitrarily large dimensions.


title:
The PRIsm MUlti-object Survey (PRIMUS). II. Data Reduction and Redshift
  Fitting

abstract:
  The PRIsm MUti-object Survey (PRIMUS) is a spectroscopic galaxy redshift
survey to z~1 completed with a low-dispersion prism and slitmasks allowing for
simultaneous observations of ~2,500 objects over 0.18 square degrees. The final
PRIMUS catalog includes ~130,000 robust redshifts over 9.1 sq. deg. In this
paper, we summarize the PRIMUS observational strategy and present the data
reduction details used to measure redshifts, redshift precision, and survey
completeness. The survey motivation, observational techniques, fields, target
selection, slitmask design, and observations are presented in Coil et al 2010.
Comparisons to existing higher-resolution spectroscopic measurements show a
typical precision of sigma_z/(1+z)=0.005. PRIMUS, both in area and number of
redshifts, is the largest faint galaxy redshift survey completed to date and is
allowing for precise measurements of the relationship between AGNs and their
hosts, the effects of environment on galaxy evolution, and the build up of
galactic systems over the latter half of cosmic history.


title: Division-Alebra/Poncare-Conjecture correspondence

abstract:
  We briefly describe the importance of division algebras and Poincar\'e
conjecture in both mathematical and physical scenarios. Mathematically, we
argue that using the torsion concept one can combine the formalisms of division
algebras and Poincar\'e conjecture. Physically, we show that both formalisms
may be the underlying mathematical tools in special relativity and cosmology.
Moreover, we explore the possibility that by using the concept of n-qubit
system, such conjecture may allow generalization the Hopf maps.


title:
Crater functions for compound materials: a route to parameter estimation
  in coupled-PDE models of ion bombardment

abstract:
  During the ion bombardment of targets containing multiple component species,
highly-ordered arrays of nanostructures are sometimes observed. Models
incorporating coupled partial differential equations, describing both
morphological and chemical evolution, seem to offer the most promise of
explaining these observations. However, these models contain many unknown
parameters, which must satisfy specific conditions in order to explain observed
behavior. The lack of knowledge of these parameters is therefore an important
barrier to the comparison of theory with experiment. Here, by adapting the
recent theory of "crater functions" to the case of binary materials, we develop
a generic framework in which many of the parameters of such models can be
estimated using the results of molecular dynamics simulations.
  As a demonstration, we apply our framework to the recent theory of Bradley
and Shipman, for the case of Ar-irradiated GaSb, in which ordered patterns were
first observed. In contrast to the requirements therein that sputtered atoms
form the dominant component of the collision cascade, and that preferential
redistribution play an important stabilizing role, we find instead that the
redistributed atoms dominate the collision cascade, and that preferential
redistribution appears negligible. Hence, the actual estimated parameters for
this system do not seem to satisfy the requirements imposed by current theory,
motivating the consideration of other potential pattern-forming mechanisms.


title:
A legal perspective of E-business and E-marketing for small and medium
  enterprises

abstract:
  Electronic businesses are witnessing enormous growth as more and more people
are switching to online platforms. The widespread use of Internet has opened
new channels to operate trade for many businesses. Also electronic marketing
has become a proven channel of passing on the word to the customers. Legal and
ethical issues quickly become an area of concern. In this research
recommendations are made to harmonize IT and Internet Laws. A novel approach is
proposed to promote legal risk management culture in organizations. It begins
with revising current state of regulations surrounding eBusinesses and
electronic marketing. The proposed approach offers risk management by
considering risk mitigation strategy, educating people and use of information
technology. Monitoring compliance requirements are met by reviewing the latest
changes in regulations and rewarding the employees who ensures the successful
implementation of the strategy.


title: Hydrodynamic Supercontinuum

abstract:
  We demonstrate experimentally multi-bound-soliton solutions of the Nonlinear
Schr\"odinger equation (NLS) in the context of surface gravity waves. In
particular, the Satsuma-Yajima N-soliton solution with N=2,3,4 is investigated
in detail. Such solutions, also known as breathers on zero background, lead to
periodic self-focussing in the wave group dynamics, and the consequent
generation of a steep localized carrier wave underneath the group envelope. Our
experimental results are compared with predictions from the NLS for low
steepness initial conditions where wave-breaking does not occur, with very good
agreement. We also show the first detailed experimental study of irreversible
massive spectral broadening of the water wave spectrum, which we refer to by
analogy with optics as the first controlled observation of hydrodynamic
supercontinuum a process which is shown to be associated with the fission of
the initial multi-soliton bound state into individual fundamental solitons
similar to what has been observe in optics.


title: Tubes of magnetic flux and electric current in space physics

abstract:
  The singularities of an irrotational magnetic field are lines of electric
current. This property derives from the relationship between vector fields and
the topology of the underlying three-space and allows for a definition of
{cosmic field} flux tubes and flux ropes as \textit{cores} (in the sense of the
physics of defects) of helical singularities. When applied to force-free flux
ropes, and assuming current conservation, an interesting feature is the
quantization of the radii, pitches, and helicities. One expects similar
quantization effects in the general case. In the special case when the total
electric current vanishes, a force-free rope embedded in a medium devoid of
magnetic field is nonetheless topologically stable, because it is the core of a
singularity of the vector potential. Magnetic merging is also discussed in the
same framework.


title: Cygnus X-1: shedding light on the spectral variability of a black hole

abstract:
  The knowledge of the spectral state of a black hole is essential for the
interpretation of data from black holes in terms of their emission models.
Based on pointed observations of Cyg X-1 with the Rossi X-ray timing Explorer
(RXTE) that are used to classify simultaneous RXTE-ASM observations, we develop
a scheme based on RXTE -ASM colors and count rates that can be used to classify
all observations of this canonical black hole that were performed between 1996
and 2011. We show that a simple count rate criterion, as used previously, leads
to a significantly higher fraction of misclassified observations. This scheme
enables us to classify single INTEGRAL-IBIS science windows and to obtain
summed spectra for the soft, intermediate and hard state with low contamination
by other states.


title: Comment on "Giant Plasticity of a Quantum Crystal"

abstract:
  In their Letter, Haziot et al. [Phys. Rev. Lett. 110 (2013) 035301] report a
novel phenomenon of giant plasticity for hcp Helium-4 quantum crystals. They
assert that Helium-4 exhibits mechanical properties not found in classical
plasticity theory. Specifically, they examine high-quality crystals as a
function of temperature and applied strain, where the shear modulus reaches a
plateau and dissipation becomes close to zero; both quantities are reported to
be independent of stress and strain, implying a reversible dissipation process
and quantum tunneling. In this Comment, we show that these signatures can be
explained with a classical model of thermally activated dislocation glide
without the need to invoke quantum tunneling or dissipationless motion.
Recently, we proposed a dislocation glide model in solid Helium-4 containing
the dissipation contribution in the presence of other dislocations with
qualitatively similar behavior [Zhou et al., Philos. Mag. Lett. 92 (2012) 608].


title:
Existence of nearly holomorphic sections on compact Hermitian symmetric
  spaces

abstract:
  Let $X=U/K$ be a compact Hermitian symmetric space, and let $\sE$ be a
$U$-homogeneous Hermitian vector bundle on $X$. In a previous paper, we showed
that the space of nearly holomorphic sections is well-adapted for harmonic
analysis in $L^2(X,\sE)$ provided that non-trivial nearly holomorphic sections
do exist. Here we investigate the problem of extending local nearly holomorphic
sections to global ones and prove the existence of non-trivial nearly
holomorphic sections. This extends the results on the $U$-type decomposition of
$L^2(X,\sE)$ from our previous paper.


title: On the paradox of pesticides

abstract:
  The paradox of pesticides was observed experimentally, which says that
pesticides may dramatically increase the population of a pest when the pest has
a natural predator. Here we use a mathematical model to study the paradox. We
find that the timing for the application of pesticides is crucial for the
resurgence or non-resurgence of the pests. In particular, regularly applying
pesticides is not a good idea as also observed in experiments. In fact, the
best time to apply pesticides is when the pest population is reasonably high.


title: Principles of Security: Human, Cyber, and Biological

abstract:
  Cybersecurity attacks are a major and increasing burden to economic and
social systems globally. Here we analyze the principles of security in
different domains and demonstrate an architectural flaw in current
cybersecurity. Cybersecurity is inherently weak because it is missing the
ability to defend the overall system instead of individual computers. The
current architecture enables all nodes in the computer network to communicate
transparently with one another, so security would require protecting every
computer in the network from all possible attacks. In contrast, other systems
depend on system-wide protections. In providing conventional security, police
patrol neighborhoods and the military secures borders, rather than defending
each individual household. Likewise, in biology, the immune system provides
security against viruses and bacteria using primarily action at the skin,
membranes, and blood, rather than requiring each cell to defend itself. We
propose applying these same principles to address the cybersecurity challenge.
This will require: (a) Enabling pervasive distribution of self-propagating
securityware and creating a developer community for such securityware, and (b)
Modifying the protocols of internet routers to accommodate adaptive security
software that would regulate internet traffic. The analysis of the immune
system architecture provides many other principles that should be applied to
cybersecurity. Among these principles is a careful interplay of detection and
action that includes evolutionary improvement. However, achieving significant
security gains by applying these principles depends strongly on remedying the
underlying architectural limitations.


title: Inequalities for generalized minors

abstract:
  It is a classical result that the absolute value of any $k$-minor of an
$r\times s$ real or complex matrix is bounded by the product of its first $k$
singular values. We generalize this statement to the context of real or complex
simple Jordan pairs with generalized minors given by Jordan algebra
determinants.


title:
Ultrasoft fermion mode and off-diagonal Boltzmann equation in
  quark-gluon plasma at high temperature

abstract:
  We derive the generalized Boltzmann equation (GBE) near equilibrium from the
Kadanoff-Baym equation for quark excitation with ultrasoft momentum (~g^2T, g:
coupling constant, T: temperature) in quantum chromodynamics (QCD) at extremely
high T, and show that the equation is equivalent to the self-consistent
equation derived in the resummed perturbation scheme used to analyze the quark
propagator. We obtain the expressions of the dispersion relation, the damping
rate, and the strength of a quark excitation with ultrasoft momentum by solving
the GBE. We also show that the GBE enables us to obtain the equation
determining the n-point function containing a pair of quarks and (n-2) gluon
external lines whose momenta are ultrasoft.


title: Bilateral Filter: Graph Spectral Interpretation and Extensions

abstract:
  In this paper we study the bilateral filter proposed by Tomasi and Manduchi,
as a spectral domain transform defined on a weighted graph. The nodes of this
graph represent the pixels in the image and a graph signal defined on the nodes
represents the intensity values. Edge weights in the graph correspond to the
bilateral filter coefficients and hence are data adaptive. Spectrum of a graph
is defined in terms of the eigenvalues and eigenvectors of the graph Laplacian
matrix. We use this spectral interpretation to generalize the bilateral filter
and propose more flexible and application specific spectral designs of
bilateral-like filters. We show that these spectral filters can be implemented
with k-iterative bilateral filtering operations and do not require expensive
diagonalization of the Laplacian matrix.


title:
Applications of an Y-88/Be photo-neutron calibration source to Dark
  Matter and Neutrino Experiments

abstract:
  The low-energy monochromatic neutron emission from an Y-88/Be source can be
exploited to mimic the few keVnr nuclear recoils expected from low-mass Weakly
Interacting Massive Particles (WIMPs) and coherent scattering of neutrinos off
nuclei. Using this source, a ~<10% quenching factor is measured for sodium
recoils below 24 keVnr in NaI[Tl]. This is considerably smaller than the 30%
typically adopted in the interpretation of the DAMA/LIBRA dark matter
experiment, resulting in a marked increase of its tension with other searches,
under the standard set of phenomenological assumptions. The method is
illustrated for other target materials (superheated and noble liquids).

categories: physics.ins-det astro-ph.CO astro-ph.IM hep-ph nucl-ex


title:
Multiband s-wave topological superconductors: role of dimensionality and
  magnetic field response

abstract:
  We further investigate a class of time-reversal-invariant two-band s-wave
topological superconductors introduced in Phys. Rev. Lett. 108, 036803 (2012).
We show how, in the presence of time-reversal symmetry, Z_2 invariants that
distinguish between trivial and non-trivial quantum phases can be constructed
by considering only one of the Kramers' sectors in which the Hamiltonian
decouples into. We find that the main features identified in our original 2D
setting remain qualitatively unchanged in 1D and 3D, with non-trivial
topological superconducting phases supporting an odd number of Kramers' pairs
of helical Majorana modes on each boundary, as long as the required $\pi$ phase
difference between gaps is maintained. We also analyze the consequences of
time-reversal symmetry-breaking either due to the presence of an applied or
impurity magnetic field or to a deviation from the intended phase matching
between the superconducting gaps. We demonstrate how the relevant notion of
topological invariance must be modified when time-reversal symmetry is broken,
and how both the persistence of gapless Majorana modes and their robustness
properties depend in general upon the way in which the original Hamiltonian is
perturbed. Interestingly, a topological quantum phase transition between
helical and chiral superconducting phases can be induced by suitably tuning a
Zeeman field in conjunction with a phase mismatch between the gaps. Recent
experiments in doped semiconducting crystals, of potential relevance to the
proposed model, and possible candidate material realizations in superconductors
with $s_\pm$ pairing symmetry are discussed.


title:
Elliptical galaxies with rapidly decreasing velocity dispersion
  profiles: NMAGIC models and dark halo parameter estimates for NGC 4494

abstract:
  NGC 4494 is one of several intermediate-luminosity elliptical galaxies
inferred to have an unusually diffuse dark matter halo. We use the
chi^2-made-to-measure particle code NMAGIC to construct axisymmetric models of
NGC 4494 from photometric and various kinematic data. The extended kinematics
include light spectra in multiple slitlets out to 3.5 R_e, and hundreds of
planetary nebulae velocities out to ~7 R_e, thus allowing us to probe the dark
matter content and orbital structure in the halo. We use Monte Carlo
simulations to estimate confidence boundaries for the halo parameters, given
our data and modelling set-up. We find that the true potential of the dark
matter halo is recovered within Delta G (merit function)<26 (Delta chi^2<59) at
70% confidence level (C.L.), and within Delta G<32 (Delta chi^2<70) at 90%
C.L.. These numbers are much larger than the usually assumed Delta chi^2=2.3
(4.6) for 70% (90%) C.L. for two free parameters, perhaps case-dependent, but
calling into question the general validity of the standard assumptions used for
halo and black hole mass determinations. The best-fitting models for NGC 4494
have a dark matter fraction of about 0.6\pm0.1 at 5R_e (70% C.L.), and are
embedded in a dark matter halo with circular velocity ~200 km/s. The total
circular velocity curve (CVC) is approximately flat at v_c=220 km/s outside
~0.5R_e. The orbital anisotropy of the stars is moderately radial. These
results are independent of the assumed inclination of the galaxy, and edge-on
models are preferred. Comparing with the halos of NGC 3379 and NGC 4697, whose
velocity dispersion profiles also decrease rapidly from the center outwards,
the outer CVCs and dark matter halos are quite similar. NGC 4494 shows a
particularly high dark matter fraction inside ~3R_e, and a strong concentration
of baryons in the center.


title:
Constraining The Assembly Of Normal And Compact Passively Evolving
  Galaxies From Redshift z=3 To The Present With CANDELS

abstract:
  We study the evolution of the number density, as a function of the size, of
passive early-type galaxies with a wide range of stellar masses
10^10<M*/Msun<10^11.5) from z~3 to z~1, exploiting the unique dataset available
in the GOODS-South field, including the recently obtained WFC3 images as a part
of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
(CANDELS). In particular, we select a sample of 107 massive (M*>10^10 M_sun),
passive (SSFR<10^-2 Gyr^-1) and morphologically spheroidal galaxies at 1.2<z<3,
taking advantage of the panchromatic dataset available for GOODS, including
VLT, CFHT, Spitzer, Chandra and HST ACS+WFC3 data. We find that at 1<z<3 the
passively evolving early-type galaxies are the reddest and most massive objects
in the Universe, and we prove that a correlation between mass, morphology,
color and star-formation activity is already in place at that epoch. We measure
a significant evolution in the mass-size relation of passive early-type
galaxies (ETGs) from z~3 to z~1, with galaxies growing on average by a factor
of 2 in size in a 3 Gyr timescale only. We witness also an increase in the
number density of passive ETGs of 50 times over the same time interval. We find
that the first ETGs to form at z>2 are all compact or ultra-compact, while
normal sized ETGs (meaning ETGs with sizes comparable to those of local
counterparts of the same mass) are the most common ETGs only at z<1. The
increase of the average size of ETGs at 0<z<1 is primarily driven by the
appearance of new large ETGs rather than by the size increase of individual
galaxies.


title: The kinematics of the Local Group in a cosmological context

abstract:
  Recent observations constrained the tangential velocity of M31 with respect
to the Milky Way (MW) to be v_tan<34.4 km/s and the radial velocity to be in
the range v_rad=-109+/- 4.4 km/s (van der Marel et al. 2012). In this study we
use a large volume high resolution N-body cosmological simulation (Bolshoi)
together with three constrained simulations to statistically study this
kinematics in the context of the LCDM. The comparison of the ensembles of
simulated pairs with the observed LG at the 1-sigma level in the uncertainties
has been done with respect to the radial and tangential velocities, the reduced
orbital energy (e_tot), angular momentum (l_orb) and the dimensionless spin
parameter, lambda. Our main results are: (i) the preferred radial and
tangential velocities for pairs in LCDM are v_rad=-80+/-20 km/s, v_tan=50+/-10
km/s, (ii) pairs around that region are 3 to 13 times more common than pairs
within the observational values, (iii) 15%to 24% of LG-like pairs in LCDM have
energy and angular momentum consistent with observations while (iv) 9% to 13%
of pairs in the same sample show similar values in the inferred dimensionless
spin parameter. It follows that within current observational uncertainties the
quasi-conserved quantities that characterize the orbit of the LG, i.e. e_tot,
r_orb and lambda, do not challenge the standard LCDM model, but the model is in
tension with regard to the actual values of the radial and tangential
velocities. This might hint to a problem of the LCDM model to reproduce the
observed LG.


title:
The rotation of surviving companion stars after type Ia supernova
  explosions in the WD+MS scenario

abstract:
  In the SD scenario of SNe Ia the companion survives the SN explosion and thus
should be visible near the center of the SN remnant and may show some unusual
features. A promising approach to test progenitor models of SNe Ia is to search
for the companion in SNRs. Here we present the results of 3D hydrodynamics
simulations of the interaction between the SN Ia blast wave and a MS companion
taking into consideration its orbital motion and spin. The primary goal of this
work is to investigate the rotation of surviving companions after SN Ia
explosions in the WD+MS scenario. We use Eggleton's code including the
optically thick accretion wind model to obtain realistic models of companions.
The impact of the SN blast wave on these companions is followed in 3D
hydrodynamic simulations employing the SPH code GADGET3. We find that the
rotation of the companion does not significantly affect the amount of stripped
mass and the kick velocity caused by the SN impact. However, in our
simulations, the rotational velocity of the companion is significantly reduced
to about 14% to 32% of its pre-explosion value due to the expansion of the
companion and the fact that 55%-89% of the initial angular momentum is carried
away by the stripped matter. Compared with the observed rotational velocity of
the presumed companion star of Tycho's SN, Tycho G, of 6 km/s the final
rotational velocity we obtain is still higher by at least a factor of two.
Whether this difference is significant, and may cast doubts on the suggestion
that Tycho G is the companion of SN 1572, has to be investigated in future
studies. Based on binary population synthesis results we present, for the first
time, the expected distribution of rotational velocities of companions after
the explosion which may provide useful information for the identification of
the surviving companion in observational searches in other historical SNRs.