title: Social Browsing & Information Filtering in Social Media

abstract:
  Social networks are a prominent feature of many social media sites, a new
generation of Web sites that allow users to create and share content. Sites
such as Digg, Flickr, and Del.icio.us allow users to designate others as
"friends" or "contacts" and provide a single-click interface to track friends'
activity. How are these social networks used? Unlike pure social networking
sites (e.g., LinkedIn and Facebook), which allow users to articulate their
online professional and personal relationships, social media sites are not, for
the most part, aimed at helping users create or foster online relationships.
Instead, we claim that social media users create social networks to express
their tastes and interests, and use them to filter the vast stream of new
submissions to find interesting content. Social networks, in fact, facilitate
new ways of interacting with information: what we call social browsing. Through
an extensive analysis of data from Digg and Flickr, we show that social
browsing is one of the primary usage modalities on these social media sites.
This finding has implications for how social media sites rate and personalize
content.


title: Extended Connection in Yang-Mills Theory

abstract:
  The three fundamental geometric components of Yang-Mills theory -gauge field,
gauge fixing and ghost field- are unified in a new object: an extended
connection in a properly chosen principal fiber bundle. To do this, it is
necessary to generalize the notion of gauge fixing by using a gauge fixing
connection instead of a section. From the equations for the extended
connection's curvature, we derive the relevant BRST transformations without
imposing the usual horizontality conditions. We show that the gauge field's
standard BRST transformation is only valid in a local trivialization and we
obtain the corresponding global generalization. By using the Faddeev-Popov
method, we apply the generalized gauge fixing to the path integral quantization
of Yang-Mills theory. We show that the proposed gauge fixing can be used even
in the presence of a Gribov's obstruction.


title: Leptoquarks: Neutrino masses and accelerator phenomenology

abstract:
  Leptoquark-Higgs interactions induce mixing between leptoquark states with
different chiralities once the electro-weak symmetry is broken. In such LQ
models Majorana neutrino masses are generated at 1-loop order. Here we
calculate the neutrino mass matrix and explore the constraints on the parameter
space enforced by the assumption that LQ-loops explain current neutrino
oscillation data. LQs will be produced at the LHC, if their masses are at or
below the TeV scale. Since the fermionic decays of LQs are governed by the same
Yukawa couplings, which are responsible for the non-trivial neutrino mass
matrix, several decay branching ratios of LQ states can be predicted from
measured neutrino data. Especially interesting is that large lepton flavour
violating rates in muon and tau final states are expected. In addition, the
model predicts that, if kinematically possible, heavier LQs decay into lighter
ones plus either a standard model Higgs boson or a $Z^0/W^{\pm}$ gauge boson.
Thus, experiments at the LHC might be able to exclude the LQ mechanism as
explanation of neutrino data.


title: Photon polarization as a probe for quark-gluon plasma dynamics

abstract:
  Prospects of measuring polarized photons emitted from a quark-gluon plasma
(QGP) are discussed. In particular, the detection of a possible quark spin
polarization in a QGP using circularly polarized photons emitted from the
plasma is studied. Photons leave the QGP without further interaction and thus
provide a primary probe for quark polarization within the QGP. We find that
photon polarization cannot solely arise due to a possible QGP momentum space
anisotropy, but may be enhanced due to it. In particular, for oblate momentum
distributions and high photon energies, quark polarization is efficiently
transfered to photon polarization. The role of competing sources of polarized
photons in heavy-ion collisions is discussed.


title: Nova V5116 Sgr and searching for superhumps in nova remnants

abstract:
  We present the period analysis of unfiltered photometric observations of
V5116 Sgr (Nova Sgr 2005 #2) and we search for superhump candidates in novae
remnants. The PDM method for period analysis is used. The masses of the novae
componets are estimated from the secondary mass -- orbital period and primary
mass -- decline time relations. We found that 13 nights of V5116 Sgr
observations in the year 2006 are modulated with a period of $0.1238 \pm
0.0001$ d ($2.9712 \pm 0.0024$ h). Following the shape of the phased light
curves and no apparent change in the value of the periodicity in different
subsamples of the data, we interpret the period as orbital in nature. The
binary system then falls within the period gap of the orbital period
distribution of cataclysmic variables. From the maximum magnitude -- rate of
decline relation, we estimate the maximum absolute visual magnitude of $M_{\rm
Vmax} = -8.85 \pm 0.04$ mag using the measured value of decline $t_{\rm 2} =
6.5 \pm 1.0$ d. The mass-period relation for cataclysmic variables yields a
secondary mass estimate of about $0.26 \pm 0.05 {\rm M}_{\rm \odot}$. We
propose that V5116 Sgr is a high inclination system showing an irradiation
effect of the secondary star. No fully developed accretion disc up to the tidal
radius with the value lower than $3.5 10^{10}$ cm is probable. The mass ratio
was estimated in a few novae and the presence or absence of superhumps in these
systems was compared with the mass ratio limit for superhumps of about 0.35. We
found that in the majority of novae with expected superhumps, this variability
has not been found yet. Therefore, more observations of these systems is
encouraged.


title: Solar system tests of scalar field models with an exponential potential

abstract:
  We consider a scenario where a scalar field has dynamics ruled by an
exponential potential, such as those arising from some quintessence type
models, and aim at obtaining phenomenological manifestations of this entity
within our Solar System. To do so, we assume a perturbative regime, derive the
perturbed Schwarzschild metric, and extract the relevant post-Newtonian
parameters.


title: The Sznajd dynamics on a directed clustered network

abstract:
  The Sznajd model is investigated in the directed Erdos--Renyi network with
the clusterization coefficient enhanced to 0.3 by the method of Holme and Kim
(Phys. Rev. E65 (2002) 026107). Within additional triangles, all six links are
present. In this network, some nodes preserve the minority opinion. The time
tau of getting equilibrium is found to follow the log-normal distribution and
it increases linearly with the system size. Its dependence on the initial
opinion distribution is different from the analytical results for fully
connected networks.


title: AGN-Induced Cavities in NGC 1399 and NGC 4649

abstract:
  We present an analysis of archival Chandra and VLA observations of the E0
galaxy NGC 1399 and the E2 galaxy NGC 4649 in which we investigate cavities in
the surrounding X-ray emitting medium caused by the central AGN. We calculate
the jet power required for the AGN to evacuate these cavities and find values
of ~8x10^{41} erg/s and ~14x10^{41} erg/s for the lobes of NGC 1399 and
~7x10^{41} erg/s and ~6x10^{41} erg/s for those of NGC 4649. We also calculate
the k/f values for each cavity, where k is the ratio of the total particle
energy to that of electrons radiating in the range of 10 MHz to 10 GHz, and f
is the volume filling factor of the plasma in the cavity. We find that the
values of k/f for the lobes of NGC 1399 are ~93 and ~190, and those of the
lobes of NGC 4649 are ~15000 and ~12000. We conclude that the assumed spectrum
describes the electron distribution in the lobes of NGC 1399 reasonably well,
and that there are few entrained particles. For NGC 4649, either there are many
entrained particles or the model spectrum does not accurately describe the
population of electrons.


title:
Magnetocaloric effect in nano- and polycrystalline manganite
  $La_{0.7}Ca_{0.3}MnO_3$

abstract:
  $La_{0.7}Ca_{0.3}MnO_3$ samples were prepared in nano- and polycrystalline
forms by sol-gel and solid state reaction methods, respectively, and
structurally characterized by synchrotron X-ray diffraction. The magnetic
properties determined by ac susceptibility and dc magnetization measurements
are discussed. The magnetocaloric effect in this nanocrystalline manganite is
spread over a broader temperature interval than in the polycrystalline case.
The relative cooling power of the poly- and nanocrystalline manganites is used
to evaluate a possible application for magnetic cooling below room temperature.


title: Negative Differential Spin Conductance by Population Switching

abstract:
  An examination of the properties of many-electron conduction through
spin-degenerate systems can lead to situations where increasing the bias
voltage applied to the system is predicted to decrease the current flowing
through it, for the electrons of a particular spin. While this does not
necessarily constitute negative differential conductance (NDC) per se, it is an
example of negative differential conductance per spin (NDSC) which to our
knowledge is discussed here for the first time. Within a many-body master
equation approach which accounts for charging effects in the Coulomb Blockade
regime, we show how this might occur.


title:
The VSOP 5 GHz Active Galactic Nucleus Survey: V. Imaging Results for
  the Remaining 140 sources

abstract:
  In February 1997, the Japanese radio astronomy satellite HALCA was launched
to provide the space-bourne element for the VLBI Space Observatory Programme
(VSOP) mission. Approximately twenty-five percent of the mission time was
dedicated to the VSOP Survey of bright compact Active Galactic Nuclei (AGN) at
5 GHz. This paper, the fifth in the series, presents images and models for the
remaining 140 sources not included in Paper III, which contained 102 sources.
For most sources, the plots of the uv-coverage, the visibility amplitude versus
uv-distance, and the high resolution image are presented. Model fit parameters
to the major radio components are determined, and the brightness temperature of
the core component for each source is calculated. The brightness temperature
distributions for all of the sources in the VSOP AGN survey are discussed.


title:
A simple proof of uniqueness of the particle trajectories for solutions
  of the Navier-Stokes equations

abstract:
  We give a simple proof of the uniqueness of fluid particle trajectories
corresponding to: 1) the solution of the two-dimensional Navier Stokes
equations with an initial condition that is only square integrable, and 2) the
local strong solution of the three-dimensional equations with an
$H^{1/2}$-regular initial condition i.e.\ with the minimal Sobolev regularity
known to guarantee uniqueness. This result was proved by Chemin & Lerner (J
Diff Eq 121 (1995) 314-328) using the Littlewood-Paley theory for the flow in
the whole space $\R^d$, $d\ge 2$. We first show that the solutions of the
differential equation $\dot{X}=u(X,t)$ are unique if $u\in
L^p(0,T;H^{(d/2)-1})$ for some $p>1$ and $\sqrt{t}\,u\in L^2(0,T;H^{(d/2)+1})$.
We then prove, using standard energy methods, that the solution of the
Navier-Stokes equations with initial condition in $H^{(d/2)-1}$ satisfies these
conditions. This proof is also valid for the more physically relevant case of
bounded domains.


title: From Wave Geometry to Fake Supergravity

abstract:
  The `Wave Geometry' equation of the pre-WWII Hiroshima program is also the
key equation of the current `fake supergravity' program. I review the status of
(fake) supersymmetric domain walls and (fake) pseudo-supersymmetric
cosmologies. An extension of the domain-wall/cosmology correspondence to a
triple correspondence with instantons shows that `pseudo-supersymmetry' has
another interpretation as Euclidean supersymmetry.


title: Angular dependence of coercivity in magnetic nanotubes

abstract:
  The nucleation field for infinite magnetic nanotubes, in the case of a
magnetic field applied parallel to the long axis of the tubes, is calculated as
a function of their geometric parameters and compared with those produced
inside the pores of anodic alumina membranes by atomic layer deposition. We
also extended this result to the case of an angular dependence. We observed a
transition from curling-mode rotation to coherent-mode rotation as a function
of the angle in which the external magnetic field is applied. Finally, we
observed that the internal radii of the tubes favors the magnetization curling
reversal.


title: Generating connected and biconnected graphs

abstract:
  We focus on the algorithm underlying the main result of [A. Mestre, R. Oeckl,
Generating loop graphs via Hopf algebra in quantum field theory. J. Math.
Phys., 47, 122302, 2006]. This is an algebraic formula to generate all
connected graphs in a recursive and efficient manner. The key feature is that
each graph carries a scalar factor given by the inverse of the order of its
group of automorphisms.
  In the present paper, we revise that algorithm on the level of graphs.
Moreover, we extend the result subsequently to further classes of connected
graphs, namely, (edge) biconnected, simple and loopless graphs. Our method
consists of basic graph transformations only.


title: Why we need to see the dark matter to understand the dark energy

abstract:
  The cosmological concordance model contains two separate constituents which
interact only gravitationally with themselves and everything else, the dark
matter and the dark energy. In the standard dark energy models, the dark matter
makes up some 20% of the total energy budget today, while the dark energy is
responsible for about 75%. Here we show that these numbers are only robust for
specific dark energy models and that in general we cannot measure the abundance
of the dark constituents separately without making strong assumptions.


title: Complete families of linearly non-degenerate rational curves

abstract:
  We prove that a complete family of linearly non-degenerate rational curves of
degree $e > 2$ in $\mathbb{P}^n$ has at most $n-1$ moduli. For $e = 2$ we prove
that such a family has at most $n$ moduli. It is unknown whether or not this is
the best possible result. The general method involves exhibiting a map from the
base of a family $X$ to the Grassmaninian of $e$-planes in $\mathbb{P}^n$ and
analyzing the resulting map on cohomology.


title:
Fusion of neutron rich oxygen isotopes in the crust of accreting neutron
  stars

abstract:
  Fusion reactions in the crust of an accreting neutron star are an important
source of heat, and the depth at which these reactions occur is important for
determining the temperature profile of the star. Fusion reactions depend
strongly on the nuclear charge $Z$. Nuclei with $Z\le 6$ can fuse at low
densities in a liquid ocean. However, nuclei with Z=8 or 10 may not burn until
higher densities where the crust is solid and electron capture has made the
nuclei neutron rich. We calculate the $S$ factor for fusion reactions of
neutron rich nuclei including $^{24}$O + $^{24}$O and $^{28}$Ne + $^{28}$Ne. We
use a simple barrier penetration model. The $S$ factor could be further
enhanced by dynamical effects involving the neutron rich skin. This possible
enhancement in $S$ should be studied in the laboratory with neutron rich
radioactive beams. We model the structure of the crust with molecular dynamics
simulations. We find that the crust of accreting neutron stars may contain
micro-crystals or regions of phase separation. Nevertheless, the screening
factors that we determine for the enhancement of the rate of thermonuclear
reactions are insensitive to these features. Finally, we calculate the rate of
thermonuclear $^{24}$O + $^{24}$O fusion and find that $^{24}$O should burn at
densities near $10^{11}$ g/cm$^3$. The energy released from this and similar
reactions may be important for the temperature profile of the star.


title:
Progress in Gauge Invariant Lagrangian Construction for Massive Higher
  Spin Fields

abstract:
  We review the recently developed general gauge invariant approach to
Lagrangian construction for massive higher spin fields in Minkowski and AdS
spaces of arbitrary dimension. Higher spin Lagrangian, describing the dynamics
of the fields with any spin, is formulated with help of BRST-BFV operator in
auxiliary Fock space. No off-shell constraints on the fields and gauge
parameters are imposed. The construction is also applied to tensor higher spin
fields with index symmetry corresponding to a multirow Young tableau.


title: RNA Secondary Structures: Complex Statics and Glassy Dynamics

abstract:
  Models for RNA secondary structures (the topology of folded RNA) without
pseudo knots are disordered systems with a complex state-space below a critical
temperature. Hence, a complex dynamical (glassy) behavior can be expected, when
performing Monte Carlo simulation. Interestingly, in contrast to most other
complex systems, the ground states and the density of states can be computed in
polynomial time exactly using transfer matrix methods. Hence, RNA secondary
structure is an ideal model to study the relation between static/thermodynamic
properties and dynamics of algorithms. Also they constitute an ideal benchmark
system for new Monte Carlo methods.
  Here we considered three different recent Monte Carlo approaches: entropic
sampling using flat histograms, optimized-weights ensembles, and ParQ, which
estimates the density of states from transition matrices.
  These methods were examined by comparing the obtained density of states with
the exact results. We relate the complexity seen in the dynamics of the Monte
Carlo algorithms to static properties of the phase space by studying the
correlations between tunneling times, sampling errors, amount of meta-stable
states and degree of ultrametricity at finite temperature.


title:
Low-momentum ring diagrams of neutron matter at and near the unitary
  limit

abstract:
  We study neutron matter at and near the unitary limit using a low-momentum
ring diagram approach. By slightly tuning the meson-exchange CD-Bonn potential,
neutron-neutron potentials with various $^1S_0$ scattering lengths such as
$a_s=-12070fm$ and $+21fm$ are constructed. Such potentials are renormalized
with rigorous procedures to give the corresponding $a_s$-equivalent
low-momentum potentials $V_{low-k}$, with which the low-momentum
particle-particle hole-hole ring diagrams are summed up to all orders, giving
the ground state energy $E_0$ of neutron matter for various scattering lengths.
At the limit of $a_s\to \pm \infty$, our calculated ratio of $E_0$ to that of
the non-interacting case is found remarkably close to a constant of 0.44 over a
wide range of Fermi-momenta. This result reveals an universality that is well
consistent with the recent experimental and Monte-Carlo computational study on
low-density cold Fermi gas at the unitary limit. The overall behavior of this
ratio obtained with various scattering lengths is presented and discussed.
Ring-diagram results obtained with $V_{low-k}$ and those with $G$-matrix
interactions are compared.


title: Normal triangulations in o-minimal structures

abstract:
  We work over an o-minimal expansion of a real closed field R. Given a closed
simplicial complex K and a finite number of definable subsets of its
realization |K| in R we prove that there exists a triangulation (K',f) of |K|
compatible with the definable subsets such that K' is a subdivision of K and f
is definably homotopic to the identity on |K|.


title: Shear Viscosity in a Gluon Gas

abstract:
  The relation of the shear viscosity coefficient to the recently introduced
transport rate is derived within relativistic kinetic theory. We calculate the
shear viscosity over entropy ratio \eta/s for a gluon gas, which involves
elastic gg-> gg perturbative QCD (PQCD) scatterings as well as inelastic
gg<->ggg PQCD bremsstrahlung. For \alpha_s=0.3 we find \eta/s=0.13 and for
\alpha_s=0.6, \eta/s=0.076. The small \eta/s values, which suggest strongly
coupled systems, are due to the gluon bremsstrahlung incorporated.


title: Spin polaron in the J1-J2 Heisenberg model

abstract:
  We have studied the validity of the spin polaron picture in the frustrated
J1-J2 Heisenberg model. For this purpose, we have computed the hole spectral
functions for the Neel, collinear, and disordered phases of this model, by
means of the self-consistent Born approximation and Lanczos exact
diagonalization on finite-size clusters. We have found that the spin polaron
quasiparticle excitation is always well defined for the magnetically ordered
Neel and collinear phases, even in the vicinity of the magnetic quantum
critical points, where the local magnetization vanishes. As a general feature,
the effect of frustration is to increase the amplitude of the multimagnon
states that build up the spin polaron wave function, leading to the reduction
of the quasiparticle coherence. Based on Lanczos results, we discuss the
validity of the spin polaron picture in the disordered phase.


title: The radiation equation of state and loop quantum gravity corrections

abstract:
  The equation of state for radiation is derived in a canonical formulation of
the electromagnetic field. This allows one to include correction terms expected
from canonical quantum gravity and to infer implications to the universe
evolution in radiation dominated epochs. Corrections implied by quantum
geometry can be interpreted in physically appealing ways, relating to the
conformal invariance of the classical equations.


title: Canonical Gravity with Fermions

abstract:
  Canonical gravity in real Ashtekar-Barbero variables is generalized to allow
for fermionic matter. The resulting torsion changes several expressions in
Holst's original vacuum analysis, which are summarized here. This in turn
requires adaptations to the known loop quantization of gravity coupled to
fermions, which is discussed on the basis of the classical analysis. As a
result, parity invariance is not manifestly realized in loop quantum gravity.


title:
A global conformal extension theorem for perfect fluid Bianchi
  space-times

abstract:
  A global extension theorem is established for isotropic singularities in
polytropic perfect fluid Bianchi space-times. When an extension is possible,
the limiting behaviour of the physical space-time near the singularity is
analysed.


title:
Existence of K\"ahler-Einstein metrics and multiplier ideal sheaves on
  del Pezzo surfaces

abstract:
  We apply Nadel's method of multiplier ideal sheaves to show that every
complex del Pezzo surface of degree at most six whose automorphism group acts
without fixed points has a K\"ahler-Einstein metric. In particular, all del
Pezzo surfaces of degree $4,5$, or $6$ and certain special del Pezzo surfaces
of lower degree are shown to have a K\"ahler-Einstein metric. This result is
not new, but the proofs given in the present paper are less involved than
earlier ones by Siu, Tian and Tian-Yau.


title:
Convergence of the K\"ahler-Ricci flow and multiplier ideal sheaves on
  del Pezzo surfaces

abstract:
  On certain del Pezzo surfaces with large automorphism groups, it is shown
that the solution to the K\"ahler-Ricci flow with a certain initial value
converges in $C^\infty$-norm exponentially fast to a K\"ahler-Einstein metric.
The proof is based on the method of multiplier ideal sheaves.


title: Hard thermal loops in the real-time formalism

abstract:
  We present a systematic discussion of Braaten and Pisarski's hard thermal
loop (HTL) effective theory within the framework of the real-time
(Schwinger-Keldysh) formalism. As is well known, the standard imaginary-time
HTL amplitudes for hot gauge theory express the polarization of a medium made
out of nonabelian charged point-particles; we show that the complete real-time
HTL theory includes, in addition, a second set of amplitudes which account for
Gaussian fluctuations in the charge distributions, but nothing else. We give a
concise set of graphical rules which generate both set of functions, and
discuss its relation to classical plasma physics.


title: INTEGRAL detection of the pulsar wind nebula in PSR J1846-0258

abstract:
  We communicate the detection of soft (20--200 keV) gamma-rays from the pulsar
and pulsar wind nebula of PSR J1846-0258 and aim to identify the component of
the system which is responsible for the gamma-ray emission. To pinpoint the
source of gamma-ray emission we combine spectral information from the INTEGRAL
gamma-ray mission with archival data from the Chandra X-ray Observatory. Our
analysis shows that the soft gamma-rays detected from PSR J1846-0258 include
emission from both the pulsar and the pulsar wind nebula, but the measured
spectral shape is dominated by the pulsar wind nebula. We further discuss PSR
J1846-0258 in the context of rotation-powered pulsars with high magnetic field
strengths and review the anomalously high fraction of spin-down luminosity
converted into X- and gamma-ray emission in light of a possible overestimate of
the distance to this pulsar.


title: The H-principle and Pseudoconcave CR Manifolds

abstract:
  The H-principle, which is the analogue, for CR manifolds, of the classical
Hartogs principle in several complex variables, is known to be valid in the
small on a pseudoconcave CR manifold of any codimension. However it fails in
the large, as has been shown by the counterexample found in [HN1]. Hence there
is an underlying obstruction to the global H-principle on a pseudoconcave CR
manifold. The purpose of this note is to take the first steps toward a deeper
understanding of this obstruction.


title: On the geometry of V-systems

abstract:
  We consider a complex version of the $\vee$-systems, which appeared in the
theory of the WDVV equation. We show that the class of these systems is closed
under the natural operations of restriction and taking the subsystems and study
a special class of the $\vee$-systems related to generalized root systems and
basic classical Lie superalgebras.


title: Supersymmetric Models for Neutrino Mass

abstract:
  We review models for neutrino mass, with special emphasis in supersymmetric
models where R-parity is broken either explicitly or spontaneously. The
simplest unified extension of the MSSM with explicit bilinear R-parity
violation provides a predictive scheme for neutrino masses and mixings which
can account for the observed atmospheric and solar neutrino anomalies. Despite
the smallness of neutrino masses R-parity violation is observable at present
and future high-energy colliders, providing an unambiguous cross-check of the
model. This model can be shown to be an effective model for the, more
theoretically satisfying, spontaneous broken theory. The main difference in
this last case is the appearance of a massless particle, the majoron, that can
modify the decay modes of the Higgs boson, making it decay invisibly most of
the time.


title: GLISSANDO: GLauber Initial-State Simulation AND mOre

abstract:
  GLISSANDO is a Glauber Monte-Carlo generator for early-stages of relativistic
heavy-ion collisions, written in c++ and interfaced to Root. Several models are
implemented: the wounded-nucleon model, the binary collisions model, the mixed
model, and the model with hot-spots. Subtleties of the distribution of nucleon
in the nucleus are discussed. The original geometric distribution of sources in
the transverse plane can be superimposed with a statistical distribution
simulating the dispersion in the generated transverse energy in each individual
collision. The program generates inter alia the fixed axes (standard) and
variable-axes (participant) two-dimensional profiles of the density of sources
in the transverse plane and their Fourier components. These profiles can be
used in further analyses of physical phenomena, such as the the jet quenching,
event-by-event hydrodynamics, or analysis of the elliptic flow and its
fluctuations. Characteristics of the event (multiplicities, eccentricities,
Fourier coefficients, etc.) are evaluated and stored in a file for further
off-line studies. A number of scripts is provided for that purpose. Supplied
variants of the code can also be used for the proton-nucleus and
deuteron-nucleus collisions.


title:
The interplay between ionized gas and massive stars in the HII galaxy
  IIZw70: integral field spectroscopy with PMAS

abstract:
  We performed an integral field spectroscopic study for the HII galaxy IIZw70
in order to investigate the interplay between its ionized interstellar medium
(ISM) and the massive star formation (SF). Observations were taken in the
optical spectral range (3700-6800 A) with the Potsdam Multi-Aperture
Spectrophotometer (PMAS) attached to the 3.5 m telescope at CAHA. We created
and analysed maps of spatially distributed emission-lines, continuum emission
and properties of the ionized ISM (e.g. physical-chemical conditions, dust
extinction, kinematics). We investigated the relation of these properties to
the spatial distribution and evolutionary stage of the massive stars. For the
first time we have detected the presence of Wolf-Rayet (WR) stars in this
galaxy. The peak of the ionized gas emission coincides with the location of the
WR bump. The region of the galaxy with lower dust extinction corresponds to the
region that shows the lowest values of velocity dispersion and radial velocity.
The overall picture suggests that the ISM of this region is being disrupted via
photoionization and stellar winds, leading to a spatial decoupling between
gas+stars and dust clouds. The bulk of dust appears to be located at the
boundaries of the region occupied by the probable ionizing cluster. We also
found that this region is associated to the nebular emission in HeII4686 and to
the intensity maximum of most emission lines. This indicates that the hard
ionizing radiation responsible for the HeII4686 nebular emission can be related
to the youngest stars. Within $\sim$ 0.4 x 0.3 kpc^2 in the central burst, we
derived O/H using direct determinations of Te[OIII]. We found abundances in the
range 12+log(O/H)=7.65-8.05, yielding an error-weighted mean of
12+log(O/H)=7.86 $\pm$0.05.


title: Tsunamis, Viscosity and the HBT Puzzle

abstract:
  The equation of state and bulk and shear viscosities are shown to be able to
affect the transverse dynamics of a central heavy ion collision. The net
entropy, along with the femtoscopic radii are shown to be affected at the
10-20% level by both shear and bulk viscosity. The degree to which these
effects help build a tsunami-like pulse is also discussed.


title: Dirac Fields in Loop Quantum Gravity and Big Bang Nucleosynthesis

abstract:
  Big Bang nucleosynthesis requires a fine balance between equations of state
for photons and relativistic fermions. Several corrections to equation of state
parameters arise from classical and quantum physics, which are derived here
from a canonical perspective. In particular, loop quantum gravity allows one to
compute quantum gravity corrections for Maxwell and Dirac fields. Although the
classical actions are very different, quantum corrections to the equation of
state are remarkably similar. To lowest order, these corrections take the form
of an overall expansion-dependent multiplicative factor in the total density.
We use these results, along with the predictions of Big Bang nucleosynthesis,
to place bounds on these corrections.


title:
Critical behavior of diluted magnetic semiconductors: the apparent
  violation and the eventual restoration of the Harris criterion for all
  regimes of disorder

abstract:
  Using large-scale Monte Carlo calculations, we consider strongly disordered
Heisenberg models on a cubic lattice with missing sites (as in diluted magnetic
semiconductors such as Ga_{1-x}Mn_{x}As). For disorder ranging from weak to
strong levels of dilution, we identify Curie temperatures and calculate the
critical exponents nu, gamma, eta, and beta finding, per the Harris criterion,
good agreement with critical indices for the pure Heisenberg model where there
is no disorder component. Moreover, we find that thermodynamic quantities (e.g.
the second moment of the magnetization per spin) self average at the
ferromagnetic transition temperature with relative fluctuations tending to zero
with increasing system size. We directly calculate effective critical exponents
for T > T_{c}, yielding values which may differ significantly from the critical
indices for the pure system, especially in the presence of strong disorder.
Ultimately, the difference is only apparent, and eventually disappears when T
is very close to T_{c}.


title: Extending the Reach of Hydrodynamics

abstract:
  Recent and ongoing improvements to hydrodynamic treatments at RHIC are
extending the physics reach of hydrodynamics, and improving the phenomenology.
Here, the links between technological improvements and the extension of physics
are emphasized.


title: A Cosmic Microwave Background feature consistent with a cosmic texture

abstract:
  The Cosmic Microwave Background provides our most ancient image of the
Universe and our best tool for studying its early evolution. Theories of high
energy physics predict the formation of various types of topological defects in
the very early universe, including cosmic texture which would generate hot and
cold spots in the Cosmic Microwave Background. We show through a Bayesian
statistical analysis that the most prominent, 5 degree radius cold spot
observed in all-sky images, which is otherwise hard to explain, is compatible
with having being caused by a texture. From this model, we constrain the
fundamental symmetry breaking energy scale to be phi_0 ~ 8.7 x 10^(15) GeV. If
confirmed, this detection of a cosmic defect will probe physics at energies
exceeding any conceivable terrestrial experiment.


title:
Factorization of nonlinear supersymmetry in one-dimensional Quantum
  Mechanics. I: general classification of reducibility and analysis of the
  third-order algebra

abstract:
  We study possible factorizations of supersymmetric (SUSY) transformations in
the one-dimensional quantum mechanics into chains of elementary Darboux
transformations with nonsingular coefficients. A classification of irreducible
(almost) isospectral transformations and of related SUSY algebras is presented.
The detailed analysis of SUSY algebras and isospectral operators is performed
for the third-order case.


title:
Interpreting scattering wave functions in the presence of
  energy-dependent interactions

abstract:
  In scattering theory, the squared relative wave function $|\phi({\bf q},{\bf
r})|^2$ is often interpreted as a weight, due to final-state interactions,
describing the probability enhancement for emission with asymptotic relative
momentum $q$. An equivalence relation also links the integral of the squared
wave function over all coordinate space to the density of states. This
relation, which plays an important role in understanding two-particle
correlation phenomenology, is altered for the case where the potential is
energy dependent, as is assumed in various forms of reaction theory. Here, the
modification to the equivalence relation is derived, and it is shown that the
squared wave function should be augmented by a additional factor if it is to
represent the emission enhancement for final-state interactions. Examples with
relativistic vector interactions, e.g., the Coulomb interaction, are presented.


title: HESS Observations and VLT Spectroscopy of PG 1553+113

abstract:
  AIMS: The properties of the very high energy (VHE; E>100 GeV) gamma-ray
emission from the high-frequency peaked BL Lac PG 1553+113 are investigated. An
attempt is made to measure the currently unknown redshift of this object.
  METHODS: VHE Observations of PG 1553+113 were made with the High Energy
Stereoscopic System (HESS) in 2005 and 2006. H+K (1.45-2.45 micron)
spectroscopy of PG 1553+113 was performed in March 2006 with SINFONI, an
integral field spectrometer of the ESO Very Large Telescope (VLT) in Chile.
  RESULTS: A VHE signal, ~10 standard deviations, is detected by HESS during
the 2 years of observations (24.8 hours live time). The integral flux above 300
GeV is (4.6 +- 0.6{stat} +- 0.9{syst}) x 10^{-12} cm^{-2} s^{-1}, corresponding
to ~3.4% of the flux from the Crab Nebula above the same threshold. The
time-averaged energy spectrum is measured from 225 GeV to ~1.3 TeV, and is
characterized by a very soft power law (photon index of Gamma = 4.5 +-
0.3{stat} +- 0.1{syst}). No evidence for any flux or spectral variations is
found on any sampled time scale within the VHE data. The redshift of PG
1553+113 could not be determined. Indeed, even though the measured SINFONI
spectrum is the most sensitive ever reported for this object at near infrared
wavelengths, and the sensitivity is comparable to the best spectroscopy at
other wavelengths, no absorption or emission lines were found in the H+K
spectrum presented here.


title:
Study of the nonlocal gauge invariant mass operator $\mathrm{Tr} \int
  d^4x F_{\mu\nu} (D^2)^{-1} F_{\mu\nu}$ in the maximal Abelian gauge

abstract:
  The nonlocal gauge invariant mass operator $\mathrm{Tr} \int d^{4}x
F_{\mu\nu} (D^2)^{-1} F_{\mu\nu}$ is investigated in Yang-Mills theories in the
maximal Abelian gauge. By means of the introduction of auxiliary fields a local
action is achieved, enabling us to use the algebraic renormalization in order
to prove the renormalizability of the resulting local model to all orders of
perturbation theory.


title: Mathematical Foundations of Supersymmetry

abstract:
  We lay down the foundations for a systematic study of differentiable and
algebraic supervarieties, with a special attention to supergroups.


title:
The Einstein-Boltzmann Relation for Thermodynamic and Hydrodynamic
  Fluctuations

abstract:
  When making the connection between the thermodynamics of irreversible
processes and the theory of stochastic processes through the
fluctuation-dissipation theorem, it is necessary to invoke a postulate of the
Einstein-Boltzmann type. For convective processes hydrodynamic fluctuations
must be included, the velocity is a dynamical variable and although the entropy
cannot depend directly on the velocity, $\delta^{2} S$ will depend on velocity
variations. Some authors do not include velocity variations in $\delta^{2} S$,
and so have to introduce a non-thermodynamic function which replaces the
entropy and does depend on the velocity. At first sight, it seems that the
introduction of such a function requires a generalisation of the
Einstein-Boltzmann relation to be invoked. We review the reason why it is not
necessary to introduce such a function, and therefore why there is no need to
generalise the Einstein-Boltzmann relation in this way. We then obtain the
fluctuation-dissipation theorem which shows some differences as compared with
the non-convective case. We also show that $\delta^{2} S$ is a Liapunov
function when it includes velocity fluctuations.


title:
On Painleve VI transcendents related to the Dirac operator on the
  hyperbolic disk

abstract:
  Dirac hamiltonian on the Poincare disk in the presence of an Aharonov-Bohm
flux and a uniform magnetic field admits a one-parameter family of self-adjoint
extensions. We determine the spectrum and calculate the resolvent for each
element of this family. Explicit expressions for Green functions are then used
to find Fredholm determinant representations for the tau function of the Dirac
operator with two branch points on the Poincare disk. Isomonodromic deformation
theory for the Dirac equation relates this tau function to a one-parameter
class of solutions of the Painleve VI equation with $\gamma=0$. We analyze long
distance behaviour of the tau function, as well as the asymptotics of the
corresponding Painleve VI transcendents as $s\to 1$. Considering the limit of
flat space, we also obtain a class of solutions of the Painleve V equation with
$\beta=0$.


title:
Random Walk on a Surface Group: Boundary Behavior of the Green's
  Function at the Spectral Radius

abstract:
  It is proved that the Green's function of the simple random walk on a surface
group of large genus decays exponentially at the spectral radius. It is also
shown that Ancona's inequalities extend to the spectral radius R, and therefore
that the Martin boundary for R-potentials coincides with the natural geometric
boundary S^1. This implies that the Green's function obeys a power law with
exponent 1/2 at the spectral radius.


title: Dynamics, Symmetries and Hadron Properties

abstract:
  We provide a snapshot of Dyson-Schwinger equation applications to the theory
and phenomenology of hadrons. Exact results for pseudoscalar mesons are
highlighted, with details relating to the U_A(1) problem. Calculated masses of
the lightest J=0,1 states are discussed. We recapitulate upon studies of
nucleon properties and give a perspective on the contribution of quark orbital
angular momentum to the spin of a nucleon at rest.


title:
Field-induced local moments around nonmagnetic impurities in metallic
  cuprates

abstract:
  We consider a defect in a strongly correlated host metal and discuss, within
a slave boson mean field formalism for the $t-t'-J$ model, the formation of an
induced paramagnetic moment which is extended over nearby sites. We study in
particular an impurity in a metallic band, suitable for modelling the optimally
doped cuprates, in a regime where the impurity moment is paramagnetic. The form
of the local susceptibility as a function of temperature and doping is found to
agree well with recent NMR experiments, without including screening processes
leading to the Kondo effect.


title: Quantum phase transitions in photonic cavities with two-level systems

abstract:
  Systems of coupled photonic cavities have been predicted to exhibit quantum
phase transitions by analogy with the Hubbard model. To this end, we have
studied topologies of few (up to six) photonic cavities each containing a
single two-level system. Quantum phase space diagrams are produced for these
systems, and compared to mean-field results. We also consider finite effective
temperature, and compare this to the notion of disorder. We find the extent of
the Mott lobes shrink analogously to the conventional Bose-Hubbard model.


title:
On the Laplace transform of some quadratic forms and the exact
  distribution of the sample variance from a gamma or uniform parent
  distribution

abstract:
  From a suitable integral representation of the Laplace transform of a
positive semi-definite quadratic form of independent real random variables with
not necessarily identical densities a univariate integral representation is
derived for the cumulative distribution function of the sample variance of
i.i.d. random variables with a gamma density, supplementing former formulas of
the author. Furthermore, from the above Laplace transform Fourier series are
obtained for the density and the distribution function of the sample variance
of i.i.d. random variables with a uniform distribution. This distribution can
be applied e.g. to a statistical test for a scale parameter.


title: Supersymmetry without a light Higgs boson at the LHC

abstract:
  We analyze the LHC phenomenology of lambdaSUSY - a version of NMSSM with a
largish SH1H2 coupling. The scalar spectrum of the model contains a 200-300 GeV
Higgs boson h with Standard-Model like properties, and heavy CP-even and CP-odd
Higgs bosons H and A with masses in 500-800 GeV range. We study the discovery
potential of H and A in the decay chains H->hh->4V->2l6j and A->Zh->Z2V->2l4j.
The dominant backgrounds are the diffuse Z6j and Z4j productions, which can be
suppressed by demanding reconstruction of V's and h's in intermediate states.
The excess of signal events allows for a discovery of both H and A with over
5sigma significance for 100 inverse fb of integrated luminosity.


title: A Vanishing Result for Toric Varieties Associated with Root Systems

abstract:
  Consider a root system $R$ and the corresponding toric variety $V_R$ whose
fan is the Weyl fan and whose lattice of characters is given by the root
lattice for $R$. We prove the vanishing of the higher cohomology groups for
certain line bundles on $V_R$ by proving a purely combinatorial result for root
systems. These results are related to a converse to Mazur's Inequality for
(simply-connected) split reductive groups.


title:
Some classifications of \infty-Harmonic maps between Riemannian
  manifolds

abstract:
  $\infty$-Harmonic maps are a generalization of $\infty$-harmonic functions.
They can be viewed as the limiting cases of p-harmonic maps as p goes to
infinity. In this paper, we give complete classifications of linear and
quadratic $\infty$-harmonic maps from and into a sphere, quadratic
$\infty$-harmonic maps between Euclidean spaces. We describe all linear and
quadratic $\infty$-harmonic maps between Nil and Euclidean spaces, between Sol
and Euclidean spaces. We also study holomorphic $\infty$-harmonic maps between
complex Euclidean spaces.


title: Integrability and reduction of Poisson group actions

abstract:
  In this paper we study Poisson actions of complete Poisson groups, without
any connectivity assumption or requiring the existence of a momentum map. For
any complete Poisson group $G$ with dual $G^\star$ we obtain a suitably
connected integrating symplectic double groupoid $\calS$. As a consequence, the
cotangent lift of a Poisson action on an integrable Poisson manifold $P$ can be
integrated to a Poisson action of the symplectic groupoid
$\poidd{\calS}{G^\star}$ on the symplectic groupoid for $P$. Finally, we show
that the quotient Poisson manifold $P/G$ is also integrable, giving an explicit
construction of a symplectic groupoid for it, by a reduction procedure on an
associated morphism of double Lie groupoids.


title:
Fine structures in the optical absorption spectra of photochemical
  silver in silver halides? A call for further research

abstract:
  A survey is presented of the work done so far to check earlier claims that a
fine structure may be observed to occur under certain circumstances in the
impurity spectral range of the optical absorption spectra of silver halides
following photostimulation in the intrinsic range. This structure, associated
with the photochemical formation of silver specks, has been questioned over the
years. We now weigh carefully the experimental evidence on the silver halides
against a background of similar data on the alkali halides, where competing
processes run slower. We come to the conclusion that present day advances in
experimental techniques may be quite adequate for providing a solid
experimental basis to solve the problem unambiguously.


title:
On axiomatic aspects of N=2 vertex superalgebras with odd formal
  variables, and deformations of N=1 vertex superalgebras

abstract:
  The notion of "N = 2 vertex superalgebra with two odd formal variables" is
presented, the main axiom being a Jacobi identity with odd formal variables in
which an N=2 superconformal shift is incorporated into the usual Jacobi
identity for a vertex superalgebra. It is shown that as a consequence of these
axioms, the N=2 vertex superalgebra is naturally a representation of the Lie
algebra isomorphic to the three-dimensional algebra of superderivations with
basis consisting of the usual conformal operator and the two N=2 superconformal
operators. The notion of N=2 Neveu-Schwarz vertex operator superalgebra with
two odd formal variables is introduced, and consequences of this notion are
derived. Various other formulations of the notion of N=2 (Neveu-Schwarz) vertex
(operator) superalgebra appearing in the mathematics and physics literature are
discussed, and several mistakes in the literature are noted and corrected. The
notion of ``N=2 (Neveu-Schwarz) vertex (operator) superalgebra with one odd
formal variable" is formulated. It is shown that this formulation naturally
arises from alternate notions of N=1 superconformality and the continuous
deformation of an N=1 (Neveu-Schwarz) vertex (operator) superalgebra with one
odd formal variable. This notion is formulated to reflect the underlying N=1
superanalytic geometry, and it is shown that the equivalence of the notions of
N=2 (Neveu-Schwarz) vertex (operator) superalgebra with one and with two odd
formal variables reflects the equivalence of N=2 superconformal and N=1
superanalytic geometry. In particular we prove that the group of formal N=2
superconformal functions vanishing at zero and invertible in a neighborhood of
zero is isomorphic to a certain subgroup of N=1 superanalytic functions
vanishing at zero and invertible in a neighborhood of zero.


title:
Signals of the QGP phase transition - a view from microscopic transport
  models

abstract:
  In this contribution the results from various transport models on different
observables - considered as possible signals of the phase transition from
hadronic matter to the quark-gluon plasma (QGP) - are briefly reviewed.


title:
Remanence of Ni nanowire arrays: Influence of size and labyrinth
  magnetic structure

abstract:
  The influence of the macroscopic size of the Ni nanowire array system on
their remanence state has been investigated. A simple magnetic phenomenological
model has been developed to obtain the remanence as a function of the
magnetostatic interactions in the array. We observe that, due to the long range
of the dipolar interactions between the wires, the size of the sample strongly
influence the remanence of the array. On the other hand, the magnetic state of
nanowires has been studied by variable field magnetic force microscopy for
different remanent states. The distribution of nanowires with the magnetization
in up or down directions and the subsequent remanent magnetization has been
deduced from the magnetic images. The existence of two short-range magnetic
orderings with similar energies can explain the typical labyrinth pattern
observed in magnetic force microscopy images of the nanowire arrays.


title: Grassmannian Beamforming for MIMO Amplify-and-Forward Relaying

abstract:
  In this paper, we derive the optimal transmitter/ receiver beamforming
vectors and relay weighting matrix for the multiple-input multiple-output
amplify-and-forward relay channel. The analysis is accomplished in two steps.
In the first step, the direct link between the transmitter (Tx) and receiver
(Rx) is ignored and we show that the transmitter and the relay should map their
signals to the strongest right singular vectors of the Tx-relay and relay-Rx
channels. Based on the distributions of these vectors for independent
identically distributed (i.i.d.) Rayleigh channels, the Grassmannian codebooks
are used for quantizing and sending back the channel information to the
transmitter and the relay. The simulation results show that even a few number
of bits can considerably increase the link reliability in terms of bit error
rate. For the second step, the direct link is considered in the problem model
and we derive the optimization problem that identifies the optimal Tx
beamforming vector. For the i.i.d Rayleigh channels, we show that the solution
to this problem is uniformly distributed on the unit sphere and we justify the
appropriateness of the Grassmannian codebook (for determining the optimal
beamforming vector), both analytically and by simulation. Finally, a modified
quantizing scheme is presented which introduces a negligible degradation in the
system performance but significantly reduces the required number of feedback
bits.


title: CN Bimodality at Low Metallicity: The Globular Cluster M53

abstract:
  We present low resolution UV-blue spectroscopic observations of red giant
stars in the globular cluster M53 ([Fe/H]=-1.84), obtained to study primordial
abundance variations and deep mixing via the CN and CH absorption bands. The
metallicity of M53 makes it an attractive target: a bimodal distribution of
3883 angstrom CN bandstrength is common in moderate- and high-metallicity
globular clusters ([Fe/H] > -1.6) but unusual in those of lower metallicity
([Fe/H] < -2.0). We find that M53 is an intermediate case, and has a broad but
not strongly bimodal distribution of CN bandstrength, with CN and CH
bandstrengths anticorrelated in the less-evolved stars. Like many other
globular clusters, M53 also exhibits a general decline in CH bandstrength and
[C/Fe] abundance with rising luminosity on the red giant branch.


title:
Discovery of Griffiths phase in itinerant magnetic semiconductor
  Fe_{1-x}Co_xS_2

abstract:
  Critical points that can be suppressed to zero temperature are interesting
because quantum fluctuations have been shown to dramatically alter electron gas
properties. Here, the metal formed by Co doping the paramagnetic insulator
FeS$_2$, Fe$_{1-x}$Co$_x$S$_2$, is demonstrated to order ferromagnetically at
$x>x_c=0.01\pm0.005$ where we observe unusual transport, magnetic, and
thermodynamic properties. We show that this magnetic semiconductor undergoes a
percolative magnetic transition with distinct similarities to the Griffiths
phase, including singular behavior at $x_c$ and zero temperature.


title: On exotic modular tensor categories

abstract:
  It has been conjectured that every $(2+1)$-TQFT is a Chern-Simons-Witten
(CSW) theory labelled by a pair $(G,\lambda)$, where $G$ is a compact Lie
group, and $\lambda \in H^4(BG;Z)$ a cohomology class. We study two TQFTs
constructed from Jones' subfactor theory which are believed to be
counterexamples to this conjecture: one is the quantum double of the even
sectors of the $E_6$ subfactor, and the other is the quantum double of the even
sectors of the Haagerup subfactor. We cannot prove mathematically that the two
TQFTs are indeed counterexamples because CSW TQFTs, while physically defined,
are not yet mathematically constructed for every pair $(G,\lambda)$. The cases
that are constructed mathematically include:
  1. $G$ is a finite group--the Dijkgraaf-Witten TQFTs;
  2. $G$ is torus $T^n$;
  3. $G$ is a connected semi-simple Lie group--the Reshetikhin-Turaev TQFTs.
  We prove that the two TQFTs are not among those mathematically constructed
TQFTs or their direct products. Both TQFTs are of the Turaev-Viro type: quantum
doubles of spherical tensor categories. We further prove that neither TQFT is a
quantum double of a braided fusion category, and give evidence that neither is
an orbifold or coset of TQFTs above. Moreover, representation of the braid
groups from the half $E_6$ TQFT can be used to build universal topological
quantum computers, and the same is expected for the Haagerup case.


title: Gluon self-interaction in the position space in Landau gauge

abstract:
  We propose a method to treat the three-gluon self-interaction vertex in the
position space in D = 4 - 2e dimensions. As an example, we calculate a two-loop
contribution to auxiliary Lcc vertex in the Landau gauge which contains the
three-gluon vertex for SU(N) Yang-Mills theory. We represent the integral
expression as a sum of separate contributions so that each of the contributions
is a double finite integral or single integral (singular or finite) in the
position space. In each double finite integral we use the freedom to shift
exponents in powers in the denominator of integrands by some multiples of e, in
order to perform at least one of the integrations by the uniqueness technique
without corrupting the first term of the decomposition in e.


title:
A Study of Excited Charm-Strange Baryons with Evidence for new Baryons
  \Xi_c(3055)^+ and \Xi_c(3123)^+

abstract:
  We present a study of excited charm-strange baryon states produced in
$e^+e^-$ annihilations at or near a center-of-mass energy of
$10.58\mathrm{Ge\kern -0.1em V}$, in a data sample with an integrated
luminosity of $384 fb^{-1}$ recorded with the BABAR detector at the PEP-II
$e^+e^-$ storage rings at the Stanford Linear Accelerator Center. We study
strong decays of charm-strange baryons to $\Lambda_c^+K^0_{\scriptscriptstyle
S}$, $\Lambda_c^+K^-$, $\Lambda_c^+K^-\pi^+$,
$\Lambda_c^+K^0_{\scriptscriptstyle S}\pi^-$,
$\Lambda_c^+K^0_{\scriptscriptstyle S}\pi^-\pi^+$, and
$\Lambda_c^+K^-\pi^+\pi^-$. This study confirms the existence of the states
$\Xi_c(2980)^+$, $\Xi_c(3077)^+$, and $\Xi_c(3077)^0$, with a more accurate
determination of the $\Xi_c(2980)^+$ mass and width. We also present evidence
for two new states, $\Xi_c(3055)^+$ and $\Xi_c(3123)^+$, decaying through the
intermediate resonant modes $\Sigma_c(2455)^{++}K^-$ and
$\Sigma_c(2520)^{++}K^-$, respectively. For each of these baryons, we measure
the yield in each final state, determine the statistical significance, and
calculate the product of the production cross-section and branching fractions.
We also measure the masses and widths of these excited charm-strange baryons.


title: Nonequilibrium dynamics of polymer translocation: a mean-field model

abstract:
  We analyse the dynamics of polymer translocation in the strong force regime
by recasting the problem into solving a differential equation with a moving
absorbing boundary. For the total translocation time, $\tau_{\rm tr}$, our
simple mean-field model predicts that $\tau_{\rm tr}\sim$ (number of
monomers)$^{1.5}$, which is in agreement with the exponent found in previous
simulation results. Our model also predicts intricate dependencies of
$\tau_{\rm tr}$ on the variations of the pulling force and of the temperature.


title:
Halo Gas Cross Sections And Covering Fractions of MgII Absorption
  Selected Galaxies

abstract:
  We examine halo gas cross sections and covering fractions, f_c, of
intermediate redshift MgII absorption selected galaxies. We computed
statistical absorber halo radii, R_x, using current values of dN/dz and
Schechter luminosity function parameters, and have compared these values to the
distribution of impact parameters and luminosities from a sample of 37
galaxies. For equivalent widths W_r(2796) > 0.3 Ang, we find 43 < R_x < 88 kpc,
depending on the lower luminosity cutoff and the slope, beta, of the
Holmberg-like luminosity scaling, R \propto L^beta. The observed distribution
of impact parameters, D, are such that several absorbing galaxies lie at D >
R_x and several non-absorbing galaxies lie at D < R_x. We deduced f_c must be
less than unity and obtain a mean of <f_c> ~ 0.5 for our sample. Moreover, the
data suggest halo radii of MgII absorbing galaxies do not follow a luminosity
scaling with beta in the range of 0.2-0.28, if f_c= 1 as previously reported.
However, provided f_c~0.5, we find that halo radii can remain consistent with a
Holmberg-like luminosity relation with beta ~ 0.2 and R* = R_x/sqrt(f_c)= 110
kpc. No luminosity scaling (beta=0) is also consistent with the observed
distribution of impact parameters if f_c < 0.37. The data support a scenario in
which gaseous halos are patchy and likely have non-symmetric geometric
distributions about the galaxies. We suggest halo gas distributions may not be
govern primarily by galaxy mass/luminosity but also by stochastic processes
local to the galaxy.


title:
Dispersion and energy spectrum of spin excitations in an underdoped
  La_1.90Sr_0.10CuO_4

abstract:
  We performed inelastic neutron experiments on underdoped
La_2-xSr_xCuO_4(x=0.10, T_c=28.6K) using a time-of-flight neutron scattering
technique. Four incommensurate peaks on the two-dimensional reciprocal plane
disperse inwards toward an antiferromagnetic zone center as the energy
increases. These peaks merge into a single peak at an energy E_cross around
w=40+-3meV. Beyond E_cross, the peak starts to broaden and ``hourglass-like''
excitations are observed. The E_cross in the underdoped sample is smaller than
that reported for the optimally doped La_1.84Sr_0.16CuO_4. The reduction of the
E_cross is explained by the doping-independent slope of the downward dispersion
below the E_cross combined with the smaller incommensurability in the
underdoped sample. In the energy spectrum of chi"(w), we observed a similar
"peak-dip-hump" structure in the energy region of 10~45meV to that reported for
the optimally doped sample. We discuss the relation between the
hourglass-shaped dispersion and the peak-dip-hump energy spectrum.


title: Hunting Galaxies to (and for) Extinction

abstract:
  In studies of star-forming regions, near-infrared excess (NIRX)
sources--objects with intrinsic colors redder than normal stars--constitute
both signal (young stars) and noise (e.g. background galaxies). We hunt down
(identify) galaxies using near-infrared observations in the Perseus
star-forming region by combining structural information, colors, and number
density estimates. Galaxies at moderate redshifts (z = 0.1 - 0.5) have colors
similar to young stellar objects (YSOs) at both near- and mid-infrared (e.g.
Spitzer) wavelengths, which limits our ability to identify YSOs from colors
alone. Structural information from high-quality near-infrared observations
allows us to better separate YSOs from galaxies, rejecting 2/5 of the YSO
candidates identified from Spitzer observations of our regions and potentially
extending the YSO luminosity function below K of 15 magnitudes where galaxy
contamination dominates. Once they are identified we use galaxies as valuable
extra signal for making extinction maps of molecular clouds. Our new iterative
procedure: the Galaxies Near Infrared Color Excess method Revisited (GNICER),
uses the mean colors of galaxies as a function of magnitude to include them in
extinction maps in an unbiased way. GNICER increases the number of background
sources used to probe the structure of a cloud, decreasing the noise and
increasing the resolution of extinction maps made far from the galactic plane.


title: DVCS at HERMES: Recent Results

abstract:
  Hard exclusive reactions are the tool to learn about generalized parton
distributions, which provide a more complete parametrization of the nucleon
than the ordinary parton distribution functions. Recent measurements by the
HERMES collaboration of the exclusive production of photons, i.e.,
Deeply-Virtual Compton Scattering, are summarized and compared to model
calculations, focusing on the measurements and model comparisons relevant to
the extraction of quark orbital angular momentum and on the measurements on
heavy nuclei.


title:
Searching for hexagonal analogues of the half-metallic half-Heusler XYZ
  compounds

abstract:
  The XYZ half-Heusler crystal structure can conveniently be described as a
tetrahedral zinc blende YZ structure which is stuffed by a slightly ionic X
species. This description is well suited to understand the electronic structure
of semiconducting 8-electron compounds such as LiAlSi (formulated
Li$^+$[AlSi]$^-$) or semiconducting 18-electron compounds such as TiCoSb
(formulated Ti$^{4+}$[CoSb]$^{4-}$). The basis for this is that [AlSi]$^-$
(with the same electron count as Si$_2$) and [CoSb]$^{4-}$ (the same electron
count as GaSb), are both structurally and electronically, zinc-blende
semiconductors. The electronic structure of half-metallic ferromagnets in this
structure type can then be described as semiconductors with stuffing magnetic
ions which have a local moment: For example, 22 electron MnNiSb can be written
Mn$^{3+}$[NiSb]$^{3-}$. The tendency in the 18 electron compound for a
semiconducting gap -- believed to arise from strong covalency -- is carried
over in MnNiSb to a tendency for a gap in one spin direction. Here we similarly
propose the systematic examination of 18-electron hexagonal compounds for
semiconducting gaps; these would be the "stuffed wurtzite" analogues of the
"stuffed zinc blende" half-Heusler compounds. These semiconductors could then
serve as the basis for possibly new families of half-metallic compounds,
attained through appropriate replacement of non-magnetic ions by magnetic ones.
These semiconductors and semimetals with tunable charge carrier concentrations
could also be interesting in the context of magnetoresistive and thermoelectric
materials.


title: Compact massive objects in Virgo galaxies: the black hole population

abstract:
  We investigate the distribution of massive black holes (MBHs) in the Virgo
cluster. Observations suggest that AGN activity is widespread in massive
galaxies (M>1e10 solar masses), while at lower galaxy masses star clusters are
more abundant, which might imply a limited presence of central black holes in
these galaxy-mass regimes. We explore if this possible threshold in MBH
hosting, is linked to nature, nurture, or a mixture of both. The nature
scenario arises naturally in hierarchical cosmologies, as MBH formation
mechanisms typically are efficient in biased systems, which would later evolve
into massive galaxies. Nurture, in the guise of MBH ejections following MBH
mergers, provides an additional mechanism that is more effective for low mass,
satellite galaxies. The combination of inefficient formation, and lower
retention of MBHs, leads to the natural explanation of the distribution of
compact massive ob jects in Virgo galaxies. If MBHs arrive to the correlation
with the host mass and velocity dispersion during merger-triggered accretion
episodes, sustained tidal stripping of the host galaxies creates a population
of MBHs which lie above the expected scaling between the holes and their host
mass, suggesting a possible environmental dependence.


title: Fisher's Zeros and Perturbative Series in Gluodynamics

abstract:
  We study the zeros of the partition function in the complex beta plane
(Fisher's zeros) in SU(2) and SU(3) gluodynamics. We discuss their effects on
the asymptotic behavior of the perturbative series for the average plaquette.
We present new methods to infer the existence of these zeros in region of the
complex beta plane where MC reweighting is not reliable. These methods are
based on the assumption that the plaquette distribution can be approximated by
a phi^4 type distribution. We give new estimates of the locations for a 4^4
lattice. For SU(2), we found zeros at beta =2.18(1) \pm i0.18(2) (which differs
from previous estimates), and at beta =2.18(1) \pm i0.22(2). For SU(3), we
confirm beta =5.54(2)\pm i0.10(2) and found additional zeros at beta
=5.54(2)\pm i0.16(2). Some of the technical material can be found in recent
preprints, in the following we emphasize the motivations (why it is important
to know the locations of the zeros) and the challenges (why it is difficult to
locate the zeros when the volume increases)


title: Pre-Poisson submanifolds

abstract:
  This is an expository and introductory note on some results obtained in
"Coisotropic embeddings in Poisson manifolds" (ArXiv math/0611480). Some
original material is contained in the last two sections, where we consider
linear Poisson structures.


title: Unparticle Searches Through Compton Scattering

abstract:
  We investigate the effects of unparticles on Compton scattering, e gamma -> e
gamma based on a future e^+e^- linear collider such as the CLIC. For different
polarization configurations, we calculate the lower limits of the unparticle
energy scale Lambda_U for a discovery reach at the center of mass energies
sqrt(s)=0.5 TeV- 3 TeV. It is shown that, especially, for smaller values of the
mass dimension d, (1 <d <1.3), and for high energies and luminosities of the
collider these bounds are very significant. As a stringent limit, we find
Lambda_U>80 TeV for d<1.3 at sqrt(s)=3 TeV, and 1 ab^(-1) integrated luminosity
per year, which is comparable with the limits calculated from other low and
high energy physics implications.


title: Physical and Wind Properties of [WC] Stars

abstract:
  We review the properties of carbon-sequence ([WC]) Wolf-Rayet central stars
of planetary nebulae (CSPNe). Differences between the subtype distribution of
[WC] stars and their massive WC cousins are discussed. We conclude that
[WO]-type differ from early-type [WC] stars as a result of weaker stellar winds
due to high surface gravities, and that late- and early-type [WC] and [WO]
stars generally span a similar range in abundances, X(He) ~ X(C) >> X(O),
consistent with a late thermal pulse, and likely progenitors to PG1159 stars.


title:
A study of Bbar -> Xi_c Lambda_c^- and Bbar -> Lambda_c^+ Lambda_c^-
  Kbar decays at BABAR

abstract:
  We report measurements of B-meson decays into two- and three-body final
states containing two charmed baryons using a sample of 230 million Y(4S) -> B
Bbar decays. We find significant signals in two modes, measuring branching
fractions BF(B^- -> \Lambda_c^+ \Lambda_c^- K^-) = (1.14 +- 0.15 +- 0.17 +-
0.60) x 10^{-3} and BF(B^- -> \Xi_c^0 \Lambda_c^-) x BF(\Xi_c^0 -> \Xi^- \pi^+)
= (2.08 +- 0.65 +- 0.29 +- 0.54) x 10^{-5}, where the uncertainties are
statistical, systematic, and from the branching fraction BF(\Lambda_c^+ -> p
K^- \pi^+), respectively. We also set upper limits at the 90% confidence level
on two other modes: BF(B0bar -> \Xi_c^+ \Lambda_c^-) x BF(\Xi_c^+ -> \Xi^-
\pi^+ \pi^+) < 5.6 x 10^{-5} and BF(B0bar -> \Lambda_c^+ \Lambda_c^- K0bar) <
1.5 x 10^{-3}. We observe structure centered at an invariant mass of 2.93
GeV/c^2 in the \Lambda_c^+ K^- mass distribution of the decay B^- ->
\Lambda_c^+ \Lambda_c^- K^-.


title: Entanglement Generation in the Scattering of One-Dimensional Particles

abstract:
  This article provides a convenient framework for quantitative evaluation of
the entanglement generated when two structureless, distinguishable particles
scatter non-relativistically in one dimension. It explores how three factors
determine the amount of entanglement generated: the momentum distributions of
the incoming particles, their masses, and the interaction potential. Two
important scales emerge, one set by the kinematics and one set by the dynamics.
This method also provides two approximate analytic formulas useful for
numerical evaluation of entanglement and reveals an interesting connection
between purity, linear coordinate transformations, and momentum uncertainties.


title:
On metallic gratings coated conformally with isotropic
  negative-phase-velocity materials

abstract:
  Application of the differential method (also called the C method) to
plane-wave diffraction by a perfectly conducting, sinusoidally corrugated
metallic grating coated with a linear, homogeneous, isotropic, lossless
dielectric-magnetic material shows that coating materials with negative index
of refraction may deliver enhanced maximum nonspecular reflection efficiencies
in comparison to coating materials with positive index of refraction.


title:
The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic
  Globular and Open Clusters

abstract:
  We validate the performance and accuracy of the current SEGUE (Sloan
Extension for Galactic Understanding and Exploration) Stellar Parameter
Pipeline (SSPP), which determines stellar atmospheric parameters (effective
temperature, surface gravity, and metallicity) by comparing derived overall
metallicities and radial velocities from selected likely members of three
globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M
67) to the literature values. Spectroscopic and photometric data obtained
during the course of the original Sloan Digital Sky Survey (SDSS-I) and its
first extension (SDSS-II/SEGUE) are used to determine stellar radial velocities
and atmospheric parameter estimates for stars in these clusters. Based on the
scatter in the metallicities derived for the members of each cluster, we
quantify the typical uncertainty of the SSPP values, sigma([Fe/H]) = 0.13 dex
for stars in the range of 4500 K < Teff < 7500 K and 2.0 < log g < 5.0, at
least over the metallicity interval spanned by the clusters studied (-2.3 <
[Fe/H] < 0). The surface gravities and effective temperatures derived by the
SSPP are also compared with those estimated from the comparison of the
color-magnitude diagrams with stellar evolution models; we find satisfactory
agreement. At present, the SSPP underestimates [Fe/H] for
near-solar-metallicity stars, represented by members of M 67 in this study, by
about 0.3 dex.


title:
Geometric approach towards stable homotopy groups of spheres. The Hopf
  invariant

abstract:
  We develop a geometric approach to stable homotopy groups of spheres in the
spirit of the work of Pontrjagin and Rokhlin. A new proof of the Hopf Invariant
One Theorem by J.F.Adams is obtained in all dimensions except 15 and 31.
  To prove that the stable Hopf invariant H: \Pi_n \to Z/2 vanishes for n>31,
we apply methods of geometric topology. The Pontrjagin-Thom construction along
with Hirsch's compression lemma identify every \alpha \in \Pi_n with the framed
bordism class of a framed immersion of a closed n-manifold into R^{n+k}, for
any given k>0. Its self-intersection M projects to an immersion f: M \to R^n
which is framed by k copies of a line bundle \kappa. It is well-known that
H(\alpha) = <w_1(\kappa)^{n-k}, [M]>. The self-intersection N of f is framed by
k copies of a plane bundle with structure group D_4. We observe that H(\alpha)
= <w_1(i^*\kappa)^{n-2k}, [\bar N]>, where i immerses the double cover \bar N
of N into M. The hardest part of the proof is to show that, after modifying f
in its skew-framed bordism class, the classifying map g: N \to K(D_4,1) factors
through K(Z/4,1), provided that n=2^l-1, l>5 and n-2k=15. This is achieved by
analyzing immersions in the regular homotopy class of f that approximate the
composition of the classifying map M \to RP^{n-k}, the projection of RP^{n-k}
onto the join of copies of S^1/(Z/4) (the standard sphere), and an embedding of
this join in R^n. The last step is proved with the quaternions.


title:
The SEGUE Stellar Parameter Pipeline. III. Comparison with
  High-Resolution Spectroscopy of SDSS/SEGUE Field Stars

abstract:
  We report high-resolution spectroscopy of 125 field stars previously observed
as part of the Sloan Digital Sky Survey and its program for Galactic studies,
the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These
spectra are used to measure radial velocities and to derive atmospheric
parameters, which we compare with those reported by the SEGUE Stellar Parameter
Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS
ugriz photometry and low-resolution (R = 2000) spectroscopy. For F- and G-type
stars observed with high signal-to-noise ratios (S/N), we empirically determine
the typical random uncertainties in the radial velocities, effective
temperatures, surface gravities, and metallicities delivered by the SSPP to be
2.4 km/s, 130 K (2.2%), 0.21 dex, and 0.11 dex, respectively, with systematic
uncertainties of a similar magnitude in the effective temperatures and
metallicities. We estimate random errors for lower S/N spectra based on
numerical simulations.


title:
Vortex Redistribution below the First-Order Transition Temperature in
  the \beta-Pyrochlore Superconductor KOs_2O_6

abstract:
  A miniature Hall sensor array was used to detect magnetic induction locally
in the vortex states of the $\beta$-pyrochlore superconductor KOs$_2$O$_6$.
Below the first-order transition at $T_{\rm p}\sim 8$ K, which is associated
with a change in the rattling motion of K ions, the lower critical field and
the remanent magnetization both show a distinct decrease, suggesting that the
electron-phonon coupling is weakened below the transition. At high magnetic
fields, the local induction shows an unexpectedly large jump at $T_{\rm p}$
whose sign changes with position inside the sample. Our results demonstrate a
novel redistribution of vortices whose energy is reduced abruptly below the
first-order transition at $T_{\rm p}$.


title:
Evolution of the Intracluster Medium Between 0.2 < z < 1.3 in a Chandra
  Sample of 70 Galaxy Clusters

abstract:
  We study the evolution of the ICM with a sample of 70 galaxy clusters
spanning 0.18 < z < 1.24. We find that X-ray luminosity and ICM mass at a fixed
temperature evolve with redshift in a manner inconsistent with the standard
self-similar model of cluster formation. Both luminosity and ICM mass evolve
more slowly toward high redshift than the self-similar prediction. We find that
evolution in these two observables can be modeled by a simple evolution in the
cluster gas mass fraction. Excluding cluster cores from measurements results in
evolution more consistent with the self-similar model than when the entire
cluster is used, indicating that the fraction of clusters with cool cores
increases with time, or that cool cores become more developed over time in
those clusters that have them; this is supported by direct study of the
redshift dependence of central surface brightness, which increases in scatter
and magnitude at low redshift. We find that isophotal size-temperature
relations evolve differently according to which isophote is used, indicating
that the central and outer regions of cluster ICM evolve differently. We show
that constraints on the evolution of the gas fraction and isophotal
size-temperature relations constraints can be combined to measure cluster
distances, and thus to constrain cosmological parameters. There are indications
that scaling relation scatter decreases at higher redshift, suggesting that
merging is not the dominant source of cluster structural variation. Our results
provide constraints for simulations attempting to model cluster physics,
indicate some difficulties for cosmological studies that assume constant
cluster gas fractions, and point toward other potentially more robust uses of
clusters for cosmological applications. (Abridged)


title:
Logarithmic singularities of Schwartz kernels and local invariants of
  conformal and CR structures

abstract:
  This paper consists of two parts. In the first part we show that in odd
dimension, as well as in even dimension below the critical weight (i.e. half
the dimension), the logarithmic singularities of Schwartz kernels and Green
kernels of conformal invariant pseudodifferential operators are linear
combinations of Weyl conformal invariants, i.e., of local conformal invariants
arising from complete tensorial contractions of the covariant derivatives of
the Lorentz ambient metric of Fefferman-Graham. In even dimension and above the
critical weight exceptional local conformal invariants may further come into
play. As a consequence, this allows us to get invariant expressions for the
logarithmic singularities of the Green kernels of the GJMS operators (including
the Yamabe and Paneitz operators). In the second part, we prove analogues of
these results in CR geometry. Namely, we prove that the logarithmic
singularities of Schwartz kernels and Green kernels of CR invariant Heisenberg
pseudodifferential operators give rise to local CR invariants, and below the
critical weight are linear combinations of complete tensorial contractions of
the covariant derivatives of Fefferman's K\"alher-Lorentz ambient metric. As a
consequence, we can obtain invariant descriptions of the logarithmic
singularities of the Green kernels of the CR GJMS operators of Gover-Graham
(including the CR Yamabe operator of Jerison-Lee).


title:
Density profiles of Ar adsorbed in slits of CO_2: spontaneous symmetry
  breaking

abstract:
  A recently reported symmetry breaking of density profiles of fluid argon
confined by two parallel solid walls of carbon dioxide is studied. The
calculations are performed in the framework of a nonlocal density functional
theory. It is shown that the existence of such asymmetrical solutions is
restricted to a special choice for the adsorption potential, where the
attraction of the solid-fluid interaction is reduced by the introduction of a
hard-wall repulsion. The behavior as a function of the slit's width is also
discussed. All the results are placed in the context of the current knowledge
on this matter.


title: On extremely amenable groups of homeomorphisms

abstract:
  A topological group $G$ is {\em extremely amenable} if every compact
$G$-space has a $G$-fixed point. Let $X$ be compact and
$G\subset{\mathrm{Homeo}} (X)$. We prove that the following are equivalent: (1)
$G$ is extremely amenable; (2) every minimal closed $G$-invariant subset of
$\exp R$ is a singleton, where $R$ is the closure of the set of all graphs of
$g\in G$ in the space $\exp (X^2)$ ($\exp$ stands for the space of closed
subsets); (3) for each $n=1,2,...$ there is a closed $G$-invariant subset $Y_n$
of $(\exp X)^n$ such that $\cup_{n=1}^\infty Y_n$ contains arbitrarily fine
covers of $X$ and for every $n\ge 1$ every minimal closed $G$-invariant subset
of $\exp Y_n$ is a singleton. This yields an alternative proof of Pestov's
theorem that the group of all order-preserving self-homeomorphisms of the
Cantor middle-third set (or of the interval $[0,1]$) is extremely amenable.


title:
Electron polarizability of crystalline solids in quantizing magnetic
  fields and topological gap numbers

abstract:
  A theory of the static electron polarizability of crystals whose energy
spectrum is modified by quantizing magnetic fields is presented. It is argued
that The polarizability is strongly affected by non-dissipative Hall currents
induced by the presence of crossed electric and magnetic fields: these can even
change its sign. Results are illustrated in detail for a two dimensional square
lattice. The polarizability and the Hall conductivity are respectively linked
to the two topological quantum numbers entering the so--called Diophantine
equation. These numbers could in principle be detected in actual experiments.


title:
The Selberg Trace Formula for Hecke operators on cocompact Kleinian
  groups

abstract:
  We compute the Selberg trace formula for Hecke operators (also called the
trace formula for modular correspondences) in the context of cocompact Kleinian
groups with finite-dimentional unitary representations. We give some
applications to the distribution of Hecke eigenvalues, and give an analogue of
Huber's theorem.


title:
Variations in Stellar Clustering with Environment: Dispersed Star
  Formation and the Origin of Faint Fuzzies

abstract:
  The observed increase in star formation efficiency with average cloud
density, from several percent in whole giant molecular clouds to ~30 or more in
cluster-forming cores, can be understood as the result of hierarchical cloud
structure if there is a characteristic density as which individual stars become
well defined. Also in this case, the efficiency of star formation increases
with the dispersion of the density probability distribution function (pdf).
Models with log-normal pdf's illustrate these effects. The difference between
star formation in bound clusters and star formation in loose groupings is
attributed to a difference in cloud pressure, with higher pressures forming
more tightly bound clusters. This correlation accounts for the observed
increase in clustering fraction with star formation rate and with the
observation of Scaled OB Associations in low pressure environments. ``Faint
fuzzie'' star clusters, which are bound but have low densities, can form in
regions with high Mach numbers and low background tidal forces. The proposal by
Burkert, Brodie & Larsen (2005) that faint fuzzies form at large radii in
galactic collisional rings, satisfies these constraints.


title:
The Proto-neutron Star Phase of the Collapsar Model and the Route to
  Long-soft Gamma-ray Bursts and Hypernovae

abstract:
  Recent stellar evolutionary calculations of low-metallicity massive
fast-rotating main-sequence stars yield iron cores at collapse endowed with
high angular momentum. It is thought that high angular momentum and black hole
formation are critical ingredients of the collapsar model of long-soft
gamma-ray bursts (GRBs). Here, we present 2D multi-group,
flux-limited-diffusion MHD simulations of the collapse, bounce, and immediate
post-bounce phases of a 35-Msun collapsar-candidate model of Woosley & Heger.
We find that, provided the magneto-rotational instability (MRI) operates in the
differentially-rotating surface layers of the millisecond-period neutron star,
a magnetically-driven explosion ensues during the proto-neutron star phase, in
the form of a baryon-loaded non-relativistic jet, and that a black hole,
central to the collapsar model, does not form. Paradoxically, and although much
uncertainty surrounds stellar mass loss, angular momentum transport, magnetic
fields, and the MRI, current models of chemically homogeneous evolution at low
metallicity yield massive stars with iron cores that may have too much angular
momentum to avoid a magnetically-driven, hypernova-like, explosion in the
immediate post-bounce phase. We surmise that fast rotation in the iron core may
inhibit, rather than enable, collapsar formation, which requires a large
angular momentum not in the core but above it. Variations in the angular
momentum distribution of massive stars at core collapse might explain both the
diversity of Type Ic supernovae/hypernovae and their possible association with
a GRB. A corollary might be that, rather than the progenitor mass, the angular
momentum distribution, through its effect on magnetic field amplification,
distinguishes these outcomes.


title:
On uniform continuity of Cauchy's function and uniform convergence of
  Cauchy's integral formula with applications

abstract:
  This study is on Cauchy's function $f(z)$ and its integral, $J[f(z)]\equiv
(2\pi i)^{-1}\oint_C f(t)dt/(t-z)$ taken along a closed simple contour $C$, in
regard to their comprehensive properties over the entire $z=x+iy$ plane
consisted of the open domain ${\cal D}^+$ bounded by $C$ and the open domain
${\cal D}^-$ outside $C$. (i) With $f(z)$ assumed to be $C^n$ ($n$ times
continuously differentiable) $\forall z\in {\cal D}^+$ and in a neighborhood of
$C$, $f(z)$ and its derivatives $f^{(n)}(z)$ are proved uniformly continuous in
the closed domain $\bar{{\cal D}^+}=[\cal D^++C]$. (ii) Under this new
assumption, integral $J[f(z)]$ and its derivatives $J_n[f(z)]=d^n J[f(z)]/dz^n$
are proved to converge uniformly in $\bar{{\cal D}^+}$, thereby rendering the
integral formula valid over the entire $z$-plane. (iii) The same claims (as for
$f(z)$ and $J[f(z)]$) are shown extended to hold for the complement function
$F(z)$, defined to be $C^n \forall z\in \bar{{\cal D}^-}=[\cal D^-+C]$, in
$\bar{{\cal D}^-}$. (iv) Further, the singularity distribution of $f(z)$ in
${\cal D}^-$ (existing unless $f(z)\equiv$ const.in the $z$-plane) is
elucidated by considering the direct problem exemplified with several typical
singularities prescribed in ${\cal D}^-$. (v) The uniform convergence theorems
for $f(z)$ and $F(z)$ shown for contour $C$ of arbitrary shape are adapted to
apply to special domains in the upper or lower half $z$-planes and those inside
and outside the unit circle $|z|=1$ to achieve the generalized Hilbert
transforms for these cases. (vi) Finally, an unsolved inverse problem to
determine all the singularities of Cauchy function $f(z)$ in domain ${\cal
D}^-$ is presented for resolution as a conjecture.


title: Topological physics in the standard model and beyond

abstract:
  Topological interactions are an essential ingredient for building consistent
low-energy theories of fermions, gauge fields and Nambu-Goldstone bosons in the
absence of explicit UV completions, such as in Little Higgs models. These
interactions are also a probe of UV completion physics that may be out of
direct experimental reach. The technology of topological, or Wess-Zumino-Witten
interactions is described, using explicit examples in the standard model and in
Little Higgs models. The construction of a simple topological action on
SU(3)/SU(2) is described. Inconsistencies in some popular Little Higgs models
are pointed out.


title: Light-Cone Coordinate System in General Relativity

abstract:
  If there is a null gradient field in 1+3 dimensional space-time, we can set
up a kind of light-cone coordinate system in the space-time. In such coordinate
system, the metric takes a simple form, which is much helpful for simplifying
and solving the Einstein's field equation. This light-cone coordinate system
has wonderful properties and has been widely used in astrophysics to calculate
parameters. In this paper, we give a detailed discussion for the structure of
space-time with light-cone coordinate system. We derive the conditions for
existence of such coordinate system, and show how to construct the light-cone
coordinate system from usual ones, then explain their geometrical and physical
meanings by examples.


title:
Congruences for Andrews' Smallest Parts Partition Function and New
  Congruences for Dyson's Rank

abstract:
  Let spt(n) denote the total number of appearances of smallest parts in the
partitions of n. Recently, Andrews showed how spt(n) is related to the second
rank moment, and proved some surprising Ramanujan-type congruences mod 5, 7 and
13. We prove a generalization of these congruences using known relations
between rank and crank moments. We obtain explicit Ramanujan-type congruences
for spt(n) mod p for p = 11, 17, 19, 29, 31 and 37. Recently, Bringmann and Ono
proved that Dyson's rank function has infinitely many Ramanujan-type
congruences. Their proof is non-constructive and utilizes the theory of weak
Maass forms. We construct two explicit nontrivial examples mod 11 using
elementary congruences between rank moments and half-integer weight Hecke
eigenforms.


title: Quantum Algorithms for Evaluating MIN-MAX Trees

abstract:
  We present a bounded-error quantum algorithm for evaluating Min-Max trees.
For a tree of size N our algorithm makes N^{1/2+o(1)} comparison queries, which
is close to the optimal complexity for this problem.


title:
Mass ordering of differential elliptic flow and its violation for phi
  mesons

abstract:
  We simulate the dynamics of Au+Au collisions at the Relativistic Heavy Ion
Collider (RHIC) with a hybrid model that treats the dense early quark-gluon
plasma (QGP) stage macroscopically as an ideal fluid, but models the dilute
late hadron resonance gas (HG) microscopically using a hadronic cascade. By
comparing with a pure hydrodynamic approach we identify effects of hadronic
viscosity on the transverse momentum spectra and differential elliptic flow
v_2(p_T). We investigate the dynamical origins of the observed mass-ordering of
v_2(p_T) for identified hadrons, focusing on dissipative effects during the
late hadronic stage. We find that, at RHIC energies, much of the finally
observed mass-splitting is generated during the hadronic stage, due to build-up
of additional radial flow. The phi meson, having a small interaction cross
section, does not fully participate in this additional flow. As a result, it
violates the mass-ordering pattern for v_2(p_T) that is observed for other
hadron species. We also show that the early decoupling of the phi meson from
the hadronic rescattering dynamics leads to interesting and unambiguous
features in the p_T-dependence of the nuclear suppression factor R_AA and of
the phi/p ratio.


title:
Gauging Spacetime Symmetries on the Worldsheet and the Geometric
  Langlands Program

abstract:
  We study the two-dimensional twisted (0,2) sigma-model on various smooth
complex flag manifolds G/B, and explore its relevance to the geometric
Langlands program. We find that an equivalence - at the level of the
holomorphic chiral algebra - between a bosonic string on G/B and a B-gauged
version of itself on G, will imply an isomorphism of classical W-algebras and a
level relation which underlie a geometric Langlands correspondence for
G=SL(N,C). This furnishes an alternative physical interpretation of the
geometric Langlands correspondence for G=SL(N,C), to that demonstrated earlier
by Kapustin and Witten via an electric-magnetic duality of four-dimensional
gauge theory. Likewise, the Hecke operators and Hecke eigensheaves will have an
alternative physical interpretation in terms of the correlation functions of
local operators in the holomorphic chiral algebra of a quasi-topological
sigma-model without boundaries. A forthcoming paper will investigate the
interpretation of a ``quantum'' geometric Langlands correspondence for
G=SL(N,C) in a similar setting, albeit with fluxes of the sigma-model moduli
which induce a ``quantum'' deformation of the relevant classical algebras
turned on.


title: The distribution of maxima of approximately Gaussian random fields

abstract:
  Motivated by the problem of testing for the existence of a signal of known
parametric structure and unknown ``location'' (as explained below) against a
noisy background, we obtain for the maximum of a centered, smooth random field
an approximation for the tail of the distribution. For the motivating class of
problems this gives approximately the significance level of the maximum score
test. The method is based on an application of a likelihood-ratio-identity
followed by approximations of local fields. Numerical examples illustrate the
accuracy of the approximations.


title:
Two point correlations of a trapped interacting Bose gas at finite
  temperature

abstract:
  We develop a computationally tractable method for calculating correlation
functions of the finite temperature trapped Bose gas that includes the effects
of s-wave interactions. Our approach uses a classical field method to model the
low energy modes and treats the high energy modes using a Hartree-Fock
description. We present results of first and second order correlation
functions, in position and momentum space, for an experimentally realistic
system in the temperature range of $0.6T_c$ to $1.0T_c$. We also characterize
the spatial coherence length of the system. Our theory should be applicable in
the critical region where experiments are now able to measure first and second
order correlations.


title: Configurations of Rank-40r Extremal Even Unimodular Lattices (r=1,2,3)

abstract:
  We show that if L is an extremal even unimodular lattice of rank 40r with
r=1,2,3 then L is generated by its vectors of norms 4r and 4r+2. Our result is
an extension of Ozeki's result for the case r=1.


title:
Cuntz semigroups of ideals and quotients and a generalized Kasparov
  Stabilization Theorem

abstract:
  Let A be a C*-algebra and I a closed two-sided ideal of A. We use the Hilbert
C*-modules picture of the Cuntz semigroup to investigate the relations between
the Cuntz semigroups of I, A and A/I. We obtain a relation on two elements of
the Cuntz semigroup of A that characterizes when they are equal in the Cuntz
semigroup of A/I. As a corollary, we show that the Cuntz semigroup functor is
exact. Replacing the Cuntz equivalence relation of Hilbert modules by their
isomorphism, we obtain a generalization of Kasparov's Stabilization theorem.


title:
Setting UBVRI Photometric Zero-Points Using Sloan Digital Sky Survey
  ugriz Magnitudes

abstract:
  We discuss the use of Sloan Digital Sky Survey (SDSS) ugriz point-spread
function (PSF) photometry for setting the zero points of UBVRI CCD images. From
a comparison with the Landolt (1992) standards and our own photometry we find
that there is a fairly abrupt change in B, V, R, & I zero points around g, r, i
~ 14.5, and in the U zero point at u ~ 16. These changes correspond to where
there is significant interpolation due to saturation in the SDSS PSF fluxes.
There also seems to be another, much smaller systematic effect for stars with
g, r > 19.5. The latter effect is consistent with a small Malmquist bias.
Because of the difficulties with PSF fluxes of brighter stars, we recommend
that comparisons of ugriz and UBVRI photometry should only be made for
unsaturated stars with g, r and i in the range 14.5 - 19.5, and u in the range
16 - 19.5. We give a prescription for setting the UBVRI zero points for CCD
images, and general equations for transforming from ugriz to UBVRI.


title:
Leptogenesis in SO(10) models with a left-right symmetric seesaw
  mechanism

abstract:
  We study leptogenesis in supersymmetric SO(10) models with a left-right
symmetric seesaw mechanism, including flavour effects and the contribution of
the next-to-lightest right-handed neutrino. Assuming M_D = M_u and hierarchical
light neutrino masses, we find that successful leptogenesis is possible for 4
out of the 8 right-handed neutrino mass spectra that are compatible with the
observed neutrino data. An accurate description of charged fermion masses
appears to be an important ingredient in the analysis.


title: Covariant Theory of Gravitation in the Spacetime with Finsler Structure

abstract:
  The theory of gravitation in the spacetime with Finsler structure is
constructed. It is shown that the theory keeps general covariance. Such theory
reduces to Einstein's general relativity when the Finsler structure is
Riemannian. Therefore, this covariant theory of gravitation is an elegant
realization of Einstein's thoughts on gravitation in the spacetime with Finsler
structure.


title:
Experimental Demonstration of the Unified Framework for the Mixed State
  Geometric Phase

abstract:
  Geometrical phases have been applied in virtually every major branch of
physics and they play an important role in topology and knot theory in
mathematics and quantum computation. However, most of the early works focus on
pure quantum states which are very unrealistic and almost never occur in
practice. The two existed definitions -Uhlmann's and Sj\"{o}qvist's- would
result in different values for the geometric phase in general. The definition
of geometric phase in mixed state scenario is still an open question. Here we
present a unified framework for both approaches within one and the same
formalism based on simple interferometry. We then present experimental results
which confirm both approaches to mixed state geometric phase and clearly
demonstrate that their unification is possible. Our experiments are furthermore
the first such to measure Uhlmann's mixed state geometric phase and show in
addition that it is different to the Sj\"{o}qvist's phase.