title:
The Role of Surface Tension for the Equation of State of Quark-Gluon
  Bags

abstract:
  The temperature and chemical potential dependent surface tension of bags is
introduced into the gas of quark-gluon bags model. The suggested model is
solved analytically. It resolves a long standing problem of a unified
description of the first and second order phase transition with the cross-over.
Such an approach is necessary to model the complicated properties of
quark-gluon plasma and hadronic matter from the first principles of statistical
mechanics. In addition to the deconfinement phase transition, we found that at
the curve of a zero surface tension coefficient there must exist the surface
induced phase tranition of the 2-nd or higher order, which separates the pure
quark gluon plasma (QGP) from the cross-over states. Thus, the present model
predicts that the critical endpoint of quantum chromodynamics is the
tricritical endpoint.


title: The Casson invariant and the word metric on the Torelli group

abstract:
  We bound the value of the Casson invariant of any integral homology 3-sphere
$M$ by a constant times the distance-squared to the identity, measured in any
word metric on the Torelli group $\T$, of the element of $\T$ associated to any
Heegaard splitting of $M$. We construct examples which show this bound is
asymptotically sharp.


title: Separable convex optimization problems with linear ascending constraints

abstract:
  Separable convex optimization problems with linear ascending inequality and
equality constraints are addressed in this paper. Under an ordering condition
on the slopes of the functions at the origin, an algorithm that determines the
optimum point in a finite number of steps is described. The optimum value is
shown to be monotone with respect to a partial order on the constraint
parameters. Moreover, the optimum value is convex with respect to these
parameters. Examples motivated by optimizations for communication systems are
used to illustrate the algorithm.


title: Phase-separation of miscible liquids in a centrifuge

abstract:
  We show that a liquid mixture in the thermodynamically stable homogeneous
phase can undergo a phase-separation transition when rotated at sufficiently
high frequency $\omega$. This phase-transition is different from the usual case
where two liquids are immiscible or where the slow sedimentation process of one
component (e.g. a polymer) is accelerated due to centrifugation. For a binary
mixture, the main coupling is due to a term $\propto \Delta\rho(\omega r)^2$,
where $\Delta\rho$ is the difference between the two liquid densities and $r$
the distance from the rotation axis. Below the critical temperature there is a
critical rotation frequency $\omega_c$, below which smooth density gradients
occur. When $\omega>\omega_c$, we find a sharp interface between the low
density liquid close to the center of the centrifuge and a high density liquid
far from the center. These findings may be relevant to various separation
processes and to the control of chemical reactions, in particular their
kinetics.


title:
High energy kink in the dispersion of a hole in an antiferromagnet --
  double-occupancy effects on electronic excitations

abstract:
  Evolution of the hole spectral function along the Gamma-(pi,pi) cut is
studied in the antiferromagnetic state of the Hubbard model. The kink in the
calculated hole dispersion, the sharp spectral-weight transfer between the
branches, and the drastically suppressed coherent spectral weight near k=(0,0),
as observed recently in the high-resolution ARPES studies of cuprate
antiferromagnets, are shown to be strongly enhanced by finite-U
double-occupancy effects. Together with the anomalous spin-wave dispersion
observed earlier in high-resolution neutron-scattering studies, the present
study provides further evidence of a unified description of magnetic and
electronic excitations in cuprate antiferromagnets in terms of the Hubbard
model.


title:
Lepton Polarization Asymmetry in B l l(bar) decays in R-parity violating
  Minimal Supersymmetric Standard Model

abstract:
  We study the implication of R-parity violating Rp Minimal Supersymmetric
Standard Model (MSSM) model in lepton polarization asymmetry ALP in B l l(bar)
decays . The analysis show that the ALP is significant in a certain
phenomenological parametric region of Yukawa couplings. We have also placed
indirect bounds on Lambda' lambda couplings as obtained from B t t(bar).


title: Gamma Ray and Neutrino Emission as a Probe of Relativistic Jets

abstract:
  Constraints on the dynamics, dissipation, and production of VHE neutrinos in
relativistic jets are derived using opacity calculations and VHE $\gamma$-ray
observations. In particular, it is demonstrated how rapid variability of the
$\gamma$-ray emission at very high energies ($> 100$ GeV) can be used to map
the location of the $\gamma$-spheres, to derive lower limits on the Doppler
factor of the $\gamma$-ray emission zone, and to constrain the photopion
production opacity. The apparent discrepancy between jet Lorentz factors
inferred from superluminal motions and source statistics in the TeV blazars and
those derived from the $\gamma$-ray emission is discussed. The relation to the
high-energy emission from the HST1 knot in M87 is briefly mentioned. Estimates
of neutrino yields in upcoming neutrino telescopes are given for various
sources. It is shown that for TeV blazars, the rapid variability of the TeV
emission implies neutrino yields well below detection limit.


title:
Design of a Spherical Wrist with Parallel Architecture: Application to
  Vertebrae of an Eel Robot

abstract:
  The design of a spherical wrist with parallel architecture is the object of
this article. This study is part of a larger project, which aims to design and
to build an eel robot for inspection of immersed piping. The kinematic analysis
of the mechanism is presented first to characterize the singular configurations
as well as the isotropic configurations. We add the design constraints related
to the application, such as (i) the compactness of the mechanism, (ii) the
symmetry of the elements in order to ensure static and dynamic balance and
(iii) the possibility of the mechanism to fill the elliptic form of the ell
sections.


title: Entanglement magnification induced by local manipulations

abstract:
  We study the entanglement capability of the evolution of a pair of qubits
evolving under unitary dynamics, when the local dynamical parameters cannot be
modified during the time-evolution. Unlike the fast local control regime, we
find that local and non-local contributions to the dynamics are strictly
interconnected. Moreover, it is possible to strongly increase the entanglement
capability by suitably initializing the characteristic energies of the two
parties.


title:
Applying the Principles of Augmented Learning to Photonics Laboratory
  Work

abstract:
  This paper introduces "OPTOTEACH", a new teaching system for photonics lab
work, designed by Harz University and successfully released on the German
market by HarzOptics. OPTOTEACH is the first POF-WDM teaching system,
specifically designed to cover a multitude of lab experiments in the field of
optical communication technology.
  It is illustrated, how this lab system is supplemented by a newly developed
optical teaching software - "OPTOSOFT" - and how the combination of system and
software creates a unique augmented learning environment. The paper details,
how the didactic concept for the software was conceptualised and introduces the
latest beta version. OPTOSOFT is specifically designed not only as an
attachment to OPTOTEACH, it also allows students to rehearse various aspects of
theoretical optics and experience a fully interactive and feature-rich
self-learning environment.
  The paper further details the first experiences educators at Harz University
have made working with the lab system as well as the teaching software. So far,
the augmented learning concept was received mostly positive, although there is
some potential for further optimisation concerning integration and pacing of
various interactive modules.


title:
Pseudospherical surfaces on time scales: a geometric definition and the
  spectral approach

abstract:
  We define and discuss the notion of pseudospherical surfaces in asymptotic
coordinates on time scales. Thus we extend well known notions of discrete
pseudospherical surfaces and smooth pseudosperical surfaces on more exotic
domains (e.g, the Cantor set). In particular, we present a new expression for
the discrete Gaussian curvature which turns out to be valid for asymptotic nets
on any time scale. We show that asymptotic Chebyshev nets on an arbitrary time
scale have constant negative Gaussian curvature. We present also the
quaternion-valued spectral problem (the Lax pair) and the Darboux-Backlund
transformation for pseudospherical surfaces (in asymptotic coordinates) on
arbitrary time scales.


title: Universal spectral correlations from the ballistic sigma model

abstract:
  We consider the semiclassical ballistic sigma-model as an effective theory
describing the quantum mechanics of classically chaotic systems. Specifically,
we elaborate on close analogies to the recently developed semiclassical theory
of quantum interference in chaotic systems and show how semiclassical
'diagrams' involving near action degenerate sets of periodic orbits emerge in
the field theoretical description. We further discuss how the universality
phenomenon (i.e. the fact that individual chaotic systems behave according to
the prescriptions of random matrix theory) can be understood from the
perspective of the field theory.


title: Passive Control Architecture for Virtual Humans

abstract:
  In the present paper, we introduce a new control architecture aimed at
driving virtual humans in interaction with virtual environments, by motion
capture. It brings decoupling of functionalities, and also of stability thanks
to passivity. We show projections can break passivity, and thus must be used
carefully. Our control scheme enables task space and internal control, contact,
and joint limits management. Thanks to passivity, it can be easily extended.
Besides, we introduce a new tool as for manikin's control, which makes it able
to build passive projections, so as to guide the virtual manikin when sharp
movements are needed.


title: Semiclassical Approach to Parametric Spectral Correlation with Spin 1/2

abstract:
  The spectral correlation of a chaotic system with spin 1/2 is universally
described by the GSE (Gaussian Symplectic Ensemble) of random matrices in the
semiclassical limit. In semiclassical theory, the spectral form factor is
expressed in terms of the periodic orbits and the spin state is simulated by
the uniform distribution on a sphere. In this paper, instead of the uniform
distribution, we introduce Brownian motion on a sphere to yield the parametric
motion of the energy levels. As a result, the small time expansion of the form
factor is obtained and found to be in agreement with the prediction of
parametric random matrices in the transition within the GSE universality class.
Moreover, by starting the Brownian motion from a point distribution on the
sphere, we gradually increase the effect of the spin and calculate the form
factor describing the transition from the GOE (Gaussian Orthogonal Ensemble)
class to the GSE class.


title: On the two-loop contributions to the pion mass

abstract:
  We derive a simplified representation for the pion mass to two loops in
three-flavour chiral perturbation theory. For this purpose, we first determine
the reduced expressions for the tensorial two-loop 2-point sunset integrals
arising in chiral perturbation theory calculations. Making use of those
relations, we obtain the expression for the pion mass in terms of the minimal
set of master integrals. On the basis of known results for these, we arrive at
an explicit analytic representation, up to the contribution from K-K-eta
intermediate states where a closed-form expression for the corresponding sunset
integral is missing. However, the expansion of this function for a small pion
mass leads to a simple representation which yields a very accurate
approximation of this contribution. Finally, we also give a discussion of the
numerical implications of our results.


title:
Non-Markovian entanglement dynamics of noisy continuous variable quantum
  channels

abstract:
  We investigate the entanglement dynamics of continuous-variable quantum
channels in terms of an entangled squeezed state of two cavity fields in a
general non-Markovian environment. Using the Feynman-Vernon influence
functional theory in the coherent-state representation, we derive an exact
master equation with time-dependent coefficients reflecting the non-Markovian
influence of the environment. The influence of environments with different
spectral densities, e.g., Ohmic, sub-Ohmic, and super-Ohmic, is numerically
studied. The non-Markovian process shows its remarkable influences on the
entanglement dynamics due to the sensitive time-dependence of the dissipation
and noise functions within the typical time scale of the environment. The Ohmic
environment shows a weak dissipation-noise effect on the entanglement dynamics,
while the sub-Ohmic and super-Ohmic environments induce much more severe noise.
In particular, the memory of the system interacting with the environment
contributes a strong decoherence effect to the entanglement dynamics in the
super-Ohmic case.


title:
Measurement of the e+e- -> K+K- cross section in the energy range
  s**(1/2) = 1.04 - 1.38 GeV with the SND detector in the experiment at the
  VEPP-2M e+e- collider

abstract:
  The cross section of the process $e^+e^- \to K^+K^-$ was measured in the
energy range $\sqrt{s}$ = 1.04--1.38 GeV in the SND experiment at the VEPP-2M
$e^+e^-$ collider. The measured cross section is described by the model of
vector meson dominance with contributions from the light vector mesons $\rho$,
$\omega$, $\phi$ and their lowest excitations. The mean statistical accuracy of
the measurement is 4.4 %, and the systematic uncertainty is 5.2 %.


title: Blue laser cooling transitions in Tm I

abstract:
  We have studied possible candidates for laser cooling transitions in
$^{169}$Tm in the spectral region 410 -- 420 nm. By means of saturation
absorption spectroscopy we have measured the hyperfine structure and rates of
two nearly closed cycling transitions from the ground state
$4\textrm{f}^{13}6\textrm{s}^2(^2\textrm{F}_0)(J_g=7/2)$ to upper states
$4\textrm{f}^{12}(^3\textrm{H}_5)5\textrm{d}_{3/2}6\textrm{s}^2(J_e=9/2)$ at
410.6 nm and
$4\textrm{f}^{12}(^3\textrm{F}_4)5\textrm{d}_{5/2}6\textrm{s}^2(J_e=9/2)$ at
420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and
48(6) ns respectively. Decay rates from these levels to neighboring
opposite-parity levels are evaluated by means of Hartree-Fock calculations. We
conclude, that the strong transition at 410.6 nm has an optical leak rate of
less then $2\cdot10^{-5}$ and can be used for efficient laser cooling of
$^{169}$Tm from a thermal atomic beam. The hyperfine structure of two other
even-parity levels which can be excited from the ground state at 409.5 nm and
418.9 nm is also measured by the same technique. In addition we give a
calculated value of $7(2)$ s$^{-1}$ for the rate of magnetic-dipole transition
at 1.14 $\mu$m between the fine structure levels
$(J_g=7/2)\leftrightarrow(J'_g=5/2)$ of the ground state which can be
considered as a candidate for applications in atomic clocks.


title: A Maslov cocycle for unitary groups

abstract:
  We introduce a 2-cocycle for symplectic and skew-hermitian hyperbolic groups
over arbitrary fields and skew fields, with values in the Witt group of
hermitian forms. This cocycle has good functorial properties: it is natural
under extension of scalars and stable, so it can be viewed as a universal
2-dimensional characteristic class for these groups. Over R and C, it coincides
with the first Chern class.


title:
The impact of initial density profile on protoplanetary disc evolution
  simulation

abstract:
  In the simulation of protoplanetary disc with a power law density profile a
disc instability is detected. The instability arises only with a power law
profile and is affected by power index. Thus the impact of initial density
profile is large within the employed numerical model.


title: Conformal Gravity Challenges String Theory

abstract:
  The cosmological constant problem and the compatibility of gravity with
quantum mechanics are the two most pressing problems in all of gravitational
theory. While string theory nicely addresses the latter, it has so far failed
to provide any compelling solution to the former. On the other hand, while
conformal gravity nicely addresses the cosmological constant problem (by
naturally quenching the amount by which the cosmological constant gravitates
rather than by quenching the cosmological constant itself), the fourth order
derivative conformal theory has long been thought to possess a ghost when
quantized. However, it has recently been shown by Bender and Mannheim that not
only do theories based on fourth order derivative equations of motion not have
ghosts, they actually never had any to begin with, with the apparent presence
of ghosts being due entirely to treating operators which were not Hermitian on
the real axis as though they were. When this is taken care of via an underlying
$\cal P$$\cal T$ symmetry that such theories are found to possess, there are
then no ghosts at all and the $S$-matrix is fully unitary. Conformal gravity is
thus advanced as a fully consistent four-dimensional alternative to
ten-dimensional string theory.


title:
Nonlinear behavior of the Chinese SSEC index with a unit root: Evidence
  from threshold unit root tests

abstract:
  We investigate the behavior of the Shanghai Stock Exchange Composite (SSEC)
index for the period from 1990:12 to 2007:06 using an unconstrained two-regime
threshold autoregressive (TAR) model with an unit root developed by Caner and
Hansen. The method allows us to simultaneously consider non-stationarity and
nonlinearity in financial time series. Our finding indicates that the Shanghai
stock market exhibits nonlinear behavior with two regimes and has unit roots in
both regimes. The important implications of the threshold effect in stock
markets are also discussed.


title:
Neutrino decay as a possible interpretation to the MiniBooNE observation
  with unparticle scenario

abstract:
  In a new measurement on neutrino oscillation $\nu_{\mu}\to\nu_e$, the
MiniBooNE Collaboration observes an excess of electron-like events at low
energy and the phenomenon may demand an explanation which obviously is beyond
the oscillation picuture. We propose that heavier neutrino $\nu_2$ decaying
into a lighter one $\nu_1$ via the transition process $\nu_{\mu}\to \nu_e+X$
where $X$ denotes any light products, could be a natural mechanism. The
theoretical model we employ here is the unparticle scenario established by
Georgi. We have studied two particular modes $\nu_\mu\to \nu_e+\Un$ and
$\nu_\mu\to \nu_e+\bar\nu_e+\nu_e$. Unfortunately, the number coming out from
the computation is too small to explain the observation. Moreover, our results
are consistent with the cosmology constraint on the neutrino lifetime and the
theoretical estimation made by other groups, therefore we can conclude that
even though neutrino decay seems plausible in this case, it indeed cannot be
the source of the peak at lower energy observed by the MiniBooNE collaboration
and there should be other mechanisms responsible for the phenomenon.


title: Non-linear Symmetry-preserving Observer on Lie Groups

abstract:
  In this paper we give a geometrical framework for the design of observers on
finite-dimensional Lie groups for systems which possess some specific
symmetries. The design and the error (between true and estimated state)
equation are explicit and intrinsic. We consider also a particular case:
left-invariant systems on Lie groups with right equivariant output. The theory
yields a class of observers such that error equation is autonomous. The
observers converge locally around any trajectory, and the global behavior is
independent from the trajectory, which reminds of the linear stationary case.


title:
Stability of vortex solitons in thermal nonlinear media with cylindrical
  symmetry

abstract:
  We analyze the salient features of vortex-ring solitons supported by
cylindrically symmetric media with nonlocal thermal nonlinearity. We discover
the existence of a maximum allowed topological charge for such vortex solitons
to be stable on propagation: Only vortex-ring solitons with topological charge
m<=2 are found to be stable. This remarkable result holds independently of the
radius of the sample.


title:
Stellar population synthesis of post-AGB stars: the s-process in
  MACHO47.2496.8

abstract:
  The low-metallicity RV Tauri star MACHO47.2496.8, recently discovered in the
Large Magellanic Cloud, is highly enriched in carbon and heavy elements
produced by the slow neutron capture process (s-process), and is most probably
a genuine post-C(N-type) asymptotic giant branch (AGB) star. We use the
analysis of the abundances of MACHO47.2496.8 to constrain free parameters in
AGB models. We test which values of the free parameters describing uncertain
physical mechanisms in AGB stars, namely the third dredge-up and the features
of the 13C neutron source, produce models that better match the abundances
observed in MACHO47.2496.8. We carry out stellar population synthesis coupled
with s-process nucleosynthesis using a synthetic stellar evolution code. The
s-process ratios observed in MACHO47.2496.8 can be matched by the same models
that explain the s-process ratios of Galactic AGB and post-AGB stars of
metallicity > Z_sun/10, except for the choice of the effectiveness of 13C as a
neutron source, which has to be lower by roughly a factor of 3 to 6. The less
effective neutron source for lower metallicities is also required when
comparing population synthesis results to observations of Galactic halo
$s$-enhanced stars, such as Pb stars. The 12C/13C ratio in MACHO47.2496.8
cannot be matched simultaneously and requires the occurrence of extra-mixing
processes. The confirmed trend of the decreased efficiency of the 13C neutron
source with metallicity requires an explanation from AGB s-process models. The
present work is to date the first comparison between theoretical models and the
detailed abundances of an extragalactic post-AGB star.


title: Lepton Universality Tests with Kaons

abstract:
  Precision data on Kl3 and Kl2 decay rates and form factors allow us to
perform significant tests of lepton universality and to constrain the strength
of non-standard interactions. The present status of these tests and new physics
searches are discussed, as obtained by combining all the available results of
the various kaon physics experiments.


title:
A Time Independent Energy Estimate for Outgoing Scalar Waves in the Kerr
  Geometry

abstract:
  The Cauchy problem for the scalar wave equation in the Kerr geometry is
considered, with initial data which is smooth and compactly supported outside
the event horizon. A time-independent energy estimate for the outgoing wave is
obtained. As an application we estimate the outgoing energy for wave-packet
initial data, uniformly as the support of the initial data is shifted to
infinity. The main mathematical tool is our previously derived integral
representation of the wave propagator.


title:
An Integrated Crosscutting Concern Migration Strategy and its
  Application to JHotDraw

abstract:
  In this paper we propose a systematic strategy for migrating crosscutting
concerns in existing object-oriented systems to aspect-based solutions. The
proposed strategy consists of four steps: mining, exploration, documentation
and refactoring of crosscutting concerns. We discuss in detail a new approach
to aspect refactoring that is fully integrated with our strategy, and apply the
whole strategy to an object-oriented system, namely the JHotDraw framework. The
result of this migration is made available as an open-source project, which is
the largest aspect refactoring available to date. We report on our experiences
with conducting this case study and reflect on the success and challenges of
the migration process, as well as on the feasibility of automatic aspect
refactoring.


title:
Relativistic stars with a linear equation of state: analogy with
  classical isothermal spheres and black holes

abstract:
  We complete our previous investigation concerning the structure and the
stability of "isothermal" spheres in general relativity. This concerns objects
that are described by a linear equation of state $P=q\epsilon$ so that the
pressure is proportional to the energy density. In the Newtonian limit $q\to
0$, this returns the classical isothermal equation of state. We consider
specifically a self-gravitating radiation (q=1/3), the core of neutron stars
(q=1/3) and a gas of baryons interacting through a vector meson field (q=1). We
study how the thermodynamical parameters scale with the size of the object and
find unusual behaviours due to the non-extensivity of the system. We compare
these scaling laws with the area scaling of the black hole entropy. We also
determine the domain of validity of these scaling laws by calculating the
critical radius above which relativistic stars described by a linear equation
of state become dynamically unstable. For photon stars, we show that the
criteria of dynamical and thermodynamical stability coincide. Considering
finite spheres, we find that the mass and entropy as a function of the central
density present damped oscillations. We give the critical value of the central
density, corresponding to the first mass peak, above which the series of
equilibria becomes unstable. Finally, we extend our results to d-dimensional
spheres. We show that the oscillations of mass versus central density disappear
above a critical dimension d_{crit}(q). For Newtonian isothermal stars (q=0) we
recover the critical dimension d_{crit}=10. For the stiffest stars (q=1) we
find d_{crit}=9 and for a self-gravitating radiation (q=1/d) we find
d_{crit}=9.96404372... very close to 10. Finally, we give analytical solutions
of relativistic isothermal spheres in 2D gravity.


title: Worm Epidemics in Wireless Adhoc Networks

abstract:
  A dramatic increase in the number of computing devices with wireless
communication capability has resulted in the emergence of a new class of
computer worms which specifically target such devices. The most striking
feature of these worms is that they do not require Internet connectivity for
their propagation but can spread directly from device to device using a
short-range radio communication technology, such as WiFi or Bluetooth. In this
paper, we develop a new model for epidemic spreading of these worms and
investigate their spreading in wireless ad hoc networks via extensive Monte
Carlo simulations. Our studies show that the threshold behaviour and dynamics
of worm epidemics in these networks are greatly affected by a combination of
spatial and temporal correlations which characterize these networks, and are
significantly different from the previously studied epidemics in the Internet.

categories: cs.NI cond-mat.stat-mech cs.CR physics.soc-ph


title:
Search for a High-Mass Diphoton State and Limits on Randall-Sundrum
  Gravitons at CDF

abstract:
  We have performed a search for new particles which decay to two photons using
1.2/fb of integrated luminosity from p-pbar collisions at sqrt(s) = 1.96 TeV
collected using the CDF II Detector at the Fermilab Tevatron. We find the
diphoton mass spectrum to be in agreement with the standard model expectation,
and set limits on the cross section times branching ratio for the
Randall-Sundrum graviton, as a function of diphoton mass. We subsequently
derive lower limits for the graviton mass of 230 GeV/c2 and 850 GeV/c2, at the
95% confidence level, for coupling parameters (k/M_Pl) of 0.01 and 0.1
respectively.


title:
Two polynomial algorithms for special maximum matching constructing in
  trees

abstract:
  For an arbitrary tree we investigate the problems of constructing a maximum
matching which minimizes or maximizes the cardinality of a maximum matching of
the graph obtained from original one by its removal and present corresponding
polynomial algorithms.


title: Counting rational points on cubic hypersurfaces

abstract:
  Let X be a geometrically integral projective cubic hypersurface defined over
the rationals, with dimension D and singular locus of dimension at most D-4.
For any \epsilon>0, we show that X contains O(B^{D+\epsilon}) rational points
of height at most B. The implied constant in this estimate depends upon the
choice of \epsilon and the coefficients of the cubic form defining X.


title:
Edge colouring models for the Tutte polynomial and related graph
  invariants

abstract:
  For integer q>1, we derive edge q-colouring models for (i) the Tutte
polynomial of a graph G on the hyperbola H_q, (ii) the symmetric weight
enumerator of the set of group-valued q-flows of G, and (iii) a more general
vertex colouring model partition function that includes these polynomials and
the principal specialization order q of Stanley's symmetric monochrome
polynomial. In the second half of the paper we exhibit a family of
non-symmetric edge q-colouring models defined on k-regular graphs, whose
partition functions for q >= k each evaluate the number of proper edge
k-colourings of G when G is Pfaffian.


title: N=2 Instanton Calculus In Closed String Background

abstract:
  In this contribution we describe how to obtain instanton effects in four
dimensional gauge theories by computing string scattering amplitudes in
D3/D(-1) brane systems. In particular we study a system of fractional D3/D(-1)
branes in a Z_2 orbifold and in a Ramond-Ramond closed string background, and
show that it describes the gauge instantons of N=2 super Yang-Mills theory and
their interactions with the graviphoton of N=2. Using string theory methods we
compute the prepotential of the effective gauge theory exploiting the
localization methods of the instanton calculus, showing that this leads to the
same information given by the topological string.


title: Constraining interacting dark energy models with flux destabilization

abstract:
  A destabilization in the transfer energy flux from the vacuum to radiation,
for two vacuum decay laws relevant to the dark energy problem, is analyzed
using the Landau-Lifshitz fluctuation hydrodynamic theory. Assuming thermal (or
near thermal) equilibrium between the vacuum and radiation, at the earliest
epoch of the Universe expansion, we show that the law due to
renormalization-group running of the cosmological constant term, with
parameters chosen not to spoil the primordial nucleosynthesis scenario, does
soon drive the flux to fluctuate beyond its statistical average value thereby
distorting the cosmic background radiation spectrum beyond observational
limits. While the law coming from the saturated holographic dark energy does
not lead the flux to wildly fluctuate, a more realistic non--saturated form
shows again such anomalous behavior.


title:
Vibrational energy relaxation (VER) of isotopically labeled amide I
  modes in cytochrome c: Theoretical investigation of VER rates and pathways

abstract:
  Using a time-dependent perturbation theory, vibrational energy relaxation
(VER) of isotopically labeled amide I modes in cytochrome c solvated with water
is investigated. Contributions to the VER are decomposed into two contributions
from the protein and water. The VER pathways are visualized using radial and
angular excitation functions for resonant normal modes. Key differences of VER
among different amide I modes are demonstrated, leading to a detailed picture
of the spatial anisotropy of the VER. The results support the experimental
observation that amide I modes in proteins relax with sub picosecond
timescales, while the relaxation mechanism turns out to be sensitive to the
environment of the amide I mode.


title: 2D velocity fields of simulated interacting disc galaxies

abstract:
  We investigate distortions in the velocity fields of disc galaxies and their
use to reveal the dynamical state of interacting galaxies at different
redshift. For that purpose, we model disc galaxies in combined
N-body/hydrodynamic simulations. 2D velocity fields of the gas are extracted
from these simulations which we place at different redshifts from z=0 to z=1 to
investigate resolution effects on the properties of the velocity field. To
quantify the structure of the velocity field we also perform a kinemetry
analysis. If the galaxy is undisturbed we find that the rotation curve
extracted from the 2D field agrees well with long-slit rotation curves. This is
not true for interacting systems, as the kinematic axis is not well defined and
does in general not coincide with the photometric axis of the system. For large
(Milky way type) galaxies we find that distortions are still visible at
intermediate redshifts but partly smeared out. Thus a careful analysis of the
velocity field is necessary before using it for a Tully-Fisher study. For small
galaxies (disc scale length ~2 kpc) even strong distortions are not visible in
the velocity field at z~0.5 with currently available angular resolution.
Therefore we conclude that current distant Tully-Fisher studies cannot give
reliable results for low-mass systems. Additionally to these studies we confirm
the power of near-infrared integral field spectrometers in combination with
adaptive optics (such as SINFONI) to study velocity fields of galaxies at high
redshift (z~2).


title: Causality and Micro-Causality in Curved Spacetime

abstract:
  We consider how causality and micro-causality are realised in QED in curved
spacetime. The photon propagator is found to exhibit novel non-analytic
behaviour due to vacuum polarization, which invalidates the Kramers-Kronig
dispersion relation and calls into question the validity of micro-causality in
curved spacetime. This non-analyticity is ultimately related to the generic
focusing nature of congruences of geodesics in curved spacetime, as implied by
the null energy condition, and the existence of conjugate points. These results
arise from a calculation of the complete non-perturbative frequency dependence
of the vacuum polarization tensor in QED, using novel world-line path integral
methods together with the Penrose plane-wave limit of spacetime in the
neighbourhood of a null geodesic. The refractive index of curved spacetime is
shown to exhibit superluminal phase velocities, dispersion, absorption (due to
\gamma \to e^+e^-) and bi-refringence, but we demonstrate that the wavefront
velocity (the high-frequency limit of the phase velocity) is indeed c, thereby
guaranteeing that causality itself is respected.


title: The Refractive Index of Curved Spacetime: the Fate of Causality in QED

abstract:
  It has been known for a long time that vacuum polarization in QED leads to a
superluminal low-frequency phase velocity for light propagating in curved
spacetime. Assuming the validity of the Kramers-Kronig dispersion relation,
this would imply a superluminal wavefront velocity and the violation of
causality. Here, we calculate for the first time the full frequency dependence
of the refractive index using world-line sigma model techniques together with
the Penrose plane wave limit of spacetime in the neighbourhood of a null
geodesic. We find that the high-frequency limit of the phase velocity (i.e. the
wavefront velocity) is always equal to c and causality is assured. However, the
Kramers-Kronig dispersion relation is violated due to a non-analyticity of the
refractive index in the upper-half complex plane, whose origin may be traced to
the generic focusing property of null geodesic congruences and the existence of
conjugate points. This puts into question the issue of micro-causality, i.e.
the vanishing of commutators of field operators at spacelike separated points,
in local quantum field theory in curved spacetime.


title: Nonabelian strings in a dense matter

abstract:
  We consider gauge theories with scalar matter with and without supersymmetry
at nonzero chemical potential. It is argued that a chemical potential plays a
role similar to the FI term. We analyze theory at weak coupling regime at large
chemical potential and argue that it supports nonabelian non-BPS strings.
Worldsheet theory on the nonabelian string in a dense matter is briefly
discussed.


title: String Landscape and the Standard Model of Particle Physics

abstract:
  In this paper we describe ideas about the string landscape, and how to relate
it to the physics of the Standard Model of particle physics. First, we give a
short status report about heterotic string compactifications. Then we focus on
the statistics of D-brane models, on the problem of moduli stabilization, and
finally on some attempts to derive a probability wave function in moduli space,
which goes beyond the purely statistical count of string vacua.


title: Parity, eulerian subgraphs and the Tutte polynomial

abstract:
  Identities obtained by elementary finite Fourier analysis are used to derive
a variety of evaluations of the Tutte polynomial of a graph G at certain points
(a,b) where (a-1)(b-1) equals 2 or 4. These evaluations are expressed in terms
of eulerian subgraphs of G and the size of subgraphs modulo 2,3,4 or 6. In
particular, a graph is found to have a nowhere-zero 4-flow if and only if there
is a correlation between the event that three subgraphs A,B,C chosen uniformly
at random have pairwise eulerian symmetric differences and the event that the
integer part of (|A| + |B| + |C|) / 3 is even. Some further evaluations of the
Tutte polynomial at points (a,b) where (a-1)(b-1) = 3 are also given that
illustrate the unifying power of the methods used. The connection between
results of Matiyasevich, Alon and Tarsi and Onn is highlighted by indicating
how they may all be derived by the techniques adopted in this paper.


title: Microcanonical quantum fluctuation theorems

abstract:
  Previously derived expressions for the characteristic function of work
performed on a quantum system by a classical external force are generalized to
arbitrary initial states of the considered system and to Hamiltonians with
degenerate spectra. In the particular case of microcanonical initial states
explicit expressions for the characteristic function and the corresponding
probability density of work are formulated. Their classical limit as well as
their relations to the respective canonical expressions are discussed. A
fluctuation theorem is derived that expresses the ratio of probabilities of
work for a process and its time reversal to the ratio of densities of states of
the microcanonical equilibrium systems with corresponding initial and final
Hamiltonians.From this Crooks-type fluctuation theorem a relation between
entropies of different systems can be derived which does not involve the time
reversed process. This entropy-from-work theorem provides an experimentally
accessible way to measure entropies.


title: On real log canonical thresholds

abstract:
  We introduce real log canonical threshold and real jumping numbers for real
algebraic functions. A real jumping number is a root of the $b$-function up to
a sign if its difference with the minimal one is less than 1. The real log
canonical threshold, which is the minimal real jumping number, coincides up to
a sign with the maximal pole of the distribution defined by the complex power
of the absolute value of the function. However, this number may be greater than
1 if the codimension of the real zero locus of the function is greater than 1.
So it does not necessarily coincide with the maximal root of the b-function up
to a sign, nor with the log canonical threshold of the complexification. In
fact, the real jumping numbers can be even disjoint from the non-integral
jumping numbers of the complexification.


title: Recent progress on supersymmetric effects in rare K decays

abstract:
  The dominant MSSM effects in the rare K decays, K+ --> pi+ nu nu bar, KL -->
pi0 nu nu bar, KL --> pi0 e+ e- and KL --> pi0 mu+ mu-, are discussed both
within and without the minimal flavor violation hypothesis, at moderate and
large tangent beta. In each case, the sensitivities to MSSM soft-breaking terms
are compared, laying emphasis on possible correlations among observables. In
most scenarios, rare K decays offer unique windows into the Delta S=1 sector of
the soft-breaking terms. Therefore, together with B-physics and collider
observables, these modes will be essential for reconstructing the still elusive
SUSY-breaking mechanism.


title: On fluctuations of closed string tachyon solitons

abstract:
  We discuss fluctuations on solitons in the dilaton/graviton/tachyon system
using the low energy effective field theory approach. It is shown that closed
string solitons are free of tachyons in this approximation, regardless of the
exact shape of the tachyon potential.


title: The autoresonance threshold into a system of weakly coupled oscillators

abstract:
  We investigate a system of two weakly coupled oscillators. It is shown that
an external periodic perturbation can lead to the capture into resonance.
Asymptotic description and numerical simulations are presented. We have
obtained the explicit formula for the threshold value for the amplitude of the
perturbation that leads to the autoresonance.


title:
Integer partitions and exclusion statistics: Limit shapes and the
  largest part of Young diagrams

abstract:
  We compute the limit shapes of the Young diagrams of the minimal difference
$p$ partitions and provide a simple physical interpretation for the limit
shapes. We also calculate the asymptotic distribution of the largest part of
the Young diagram and show that the scaled distribution has a Gumbel form for
all $p$. This Gumbel statistics for the largest part remains unchanged even for
general partitions of the form $E=\sum_i n_i i^{1/\nu}$ with $\nu>0$ where
$n_i$ is the number of times the part $i$ appears.

categories: cond-mat.stat-mech math-ph math.CO math.MP


title:
Finite-dimensional irreducible modules for the three-point
  $\mathfrak{sl}_2$ loop algebra

abstract:
  Recently Brian Hartwig and the second author found a presentation for the
three-point $sl_2$ loop algebra by generators and relations. To obtain this
presentation they defined a Lie algebra $\boxtimes$ by generators and
relations, and displayed an isomorphism from $\boxtimes$ to the three-point
$sl_2$ loop algebra. In this paper we describe the finite-dimensional
irreducible $\boxtimes$-modules from multiple points of view.


title: Odderon with a running coupling constant

abstract:
  The running coupling is introduced into the equation for the odderon via the
bootstrap relation. It is shown that the previously found odderon state with a
maximal intercept, which is constructed from antisymmetric pomeron wave
function, continues to exist in the running coupling case. Its intercept is
found to remain equal to unity independent of the behaviour assumed for the
running coupling at low momenta.


title:
Consistent Kaluza-Klein Reductions for General Supersymmetric AdS
  Solutions

abstract:
  For the most general supersymmetric solutions of type IIB supergravity
consisting of a warped product of AdS_5 with a five-dimensional manifold M_5,
we construct an explicit consistent Kaluza-Klein reduction on M_5 to minimal
D=5 gauged supergravity. Thus, any solution of the gauged supergravity can be
uplifted on M_5 to obtain an exact solution of type IIB supergravity. We also
show that for general AdS_4 x SE_7 solutions, where SE_7 is a seven-dimensional
Sasaki-Einstein manifold, and for a general class of supersymmetric solutions
that are a warped product of AdS_4 with a seven-dimensional manifold N_7, there
is an analogous consistent reduction to minimal D=4 gauged supergravity.


title: Galaxy redshift surveys selected by neutral hydrogen using FAST

abstract:
  We discuss the possibility of performing a substantial spectroscopic galaxy
redshift survey selected via the 21cm emission from neutral hydrogen using the
Five-hundred metre Aperture Spherical Telescope (FAST) to be built in China. We
consider issues related to the estimation of the source counts and
optimizations of the survey, and discuss the constraints on cosmological models
that such a survey could provide. We find that a survey taking around two years
could detect ~10^7 galaxies with an average redshift of ~0.15 making the survey
complementary to those already carried out at optical wavelengths. These
conservative estimates have used the z=0 HI mass function and have ignored the
possibility of evolution. The results could be used to constrain Gamma =
(Omega_m h) to 5 per cent and the spectral index, n_s, to 7 per cent
independent of cosmic microwave background data. If we also use simulated power
spectra from the Planck satellite, we can constrain w to be within 5 per cent
of -1.


title: TDDFT and Strongly Correlated Systems: Insight From Numerical Studies

abstract:
  We illustrate the scope of Time Dependent Density Functional Theory (TDDFT)
for strongly correlated (lattice) models out of equilibrium. Using the exact
many body time evolution, we reverse engineer the exact exchange correlation
(xc) potential $v_{xc}$ for small Hubbard chains exposed to time-dependent
fields. We introduce an adiabatic local density approximation (ALDA) to
$v_{xc}$ for the 1D Hubbard model and compare it to exact results, to gain
insight about approximate xc potentials. Finally, we provide some remarks on
the v-representability for the 1D Hubbard model.


title: Angular Momentum Imparted To Test Particles by Gravitational Waves

abstract:
  What are gravitational waves? How do they propagate? and what is their energy
content? These questions are addressed in the first two chapters. In the third
chapter the pseudo-Newtonian formalism and its extension is reviewed in general
and the formula for the momentum imparted to test particles in arbitrary
spacetimes is reviewed in particular. In chapter four the analysis of a paper
claiming to determine the spin for gravitational waves is given, and compared
with the spin given by a geodesic analysis. It is demonstrated that the other
claim is inconsistent. Finally in chapter five a summary of the work is given
with the conclusion.


title: Classical mechanics as nonlinear quantum mechanics

abstract:
  All measurable predictions of classical mechanics can be reproduced from a
quantum-like interpretation of a nonlinear Schrodinger equation. The key
observation leading to classical physics is the fact that a wave function that
satisfies a linear equation is real and positive, rather than complex. This has
profound implications on the role of the Bohmian classical-like interpretation
of linear quantum mechanics, as well as on the possibilities to find a
consistent interpretation of arbitrary nonlinear generalizations of quantum
mechanics.


title:
Prompt photons in heavy ion collisions at the LHC: A ''multi-purpose''
  observable

abstract:
  I emphasize in this contribution how prompt photons can be used to probe
nuclear parton densities as well as medium-modified fragmentation functions in
heavy ion collisions. Various predictions in p-A and A-A collisions at LHC
energies are given.


title: Chern-Simons classes of flat connections on supermanifolds

abstract:
  In this note we define Chern-Simons classes of a superconnection $D+L$ on a
complex supervector bundle $E$ such that $D$ is flat and preserves the grading,
and $L$ is an odd endomorphism of $E$ on a supermanifold. As an application we
obtain a definition of Chern-Simons classes of a (not necessarily flat)
morphism between flat vector bundles on a smooth manifold. We extend Reznikov's
theorem on triviality of these classes when the manifold is a compact K\"ahler
manifold or a smooth complex quasi--projective variety, in degrees > 1.


title:
The correlation between soft and hard X-rays component in flares: from
  the Sun to the stars

abstract:
  In this work we study the correlation between the soft (1.6--12.4 keV, mostly
thermal) and the hard (20--40 and 60--80 keV, mostly non-thermal) X-ray
emission in solar flares up to the most energetic events, spanning about 4
orders of magnitude in peak flux, establishing a general scaling law and
extending it to the most intense stellar flaring events observed to date. We
used the data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager
(RHESSI) spacecraft, a NASA Small Explorer launched in February 2002. RHESSI
has good spectral resolution (~1 keV in the X-ray range) and broad energy
coverage (3 keV--20 MeV), which makes it well suited to distinguish the thermal
from non-thermal emission in solar flares. Our study is based on the detailed
analysis of 45 flares ranging from the GOES C-class, to the strongest X-class
events, using the peak photon fluxes in the GOES 1.6--12.4 keV and in two bands
selected from RHESSI data, i.e.20--40 keV and 60--80 keV. We find a significant
correlation between the soft and hard peak X-ray fluxes spanning the complete
sample studied. The resulting scaling law has been extrapolated to the case of
the most intense stellar flares observed, comparing it with the stellar
observations. Our results show that an extrapolation of the scaling law derived
for solar flares to the most active stellar events is compatible with the
available observations of intense stellar flares in hard X-rays.


title: Violation of the Appelquist-Carazzone decoupling in non-SUSY GUT

abstract:
  We point out that in non supersymmetric GUTs, in which the SU(5) gauge
symmetry is broken down to the Standard Model gauge group by a $\mathbf{24}$
Higgs multiplet the Appelquist-Carazzone decoupling is violated. This is
because the $SU(2)_L$ Higgs triplet contained in the $\mathbf{24}$ acquires a
dimensionfull coupling to the $SU(2)_L$ Higgs doublets which is proportional to
the GUT breaking vacuum expectation value (VEV) $V$. As a result, at one loop
heavy gauge and Higgs fields contribution to tadpoles generate a VEV of the
triplet which is not suppressed for $V\to\infty$ and violates the custodial
symmetry.


title: Search for medium modification of the $\rho$ meson

abstract:
  The photoproduction of vector mesons on various nuclei has been studied using
the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory. The
vector mesons, $\rho$, $\omega$, and $\phi$, are observed via their decay to
$e^+e^-$, in order to reduce the effects of final state interactions in the
nucleus. Of particular interest are possible in-medium effects on the
properties of the $\rho$ meson. The $\rho$ spectral function is extracted from
the data on various nuclei, carbon, iron, and titanium, and compared to the
spectrum from liquid deuterium, which is relatively free of nuclear effects. We
observe no significant mass shift for the $\rho$ meson; however, there is some
widening of the resonance in titanium and iron, which is consistent with
expected collisional broadening.


title: SiPM used as fast Photon-Counting Module and for Multiphoton Detection

abstract:
  We demonstrate fast counting and multiphoton detection abilities of a Silicon
Photo Multiplier (SiPM). In fast counting mode we are able to detect two
consecutive photons separated by only 2.3 ns corresponding to 430 MHz. The
counting efficiency for small optical intensities at a wavelength of 532 nm was
found to be around 8.3% with a dark count rate of 50 kHz at T=-7 degrees
Celsius. Using the SiPM in multiphoton detection mode, we find a good signal
discrimination for different numbers of simultaneous detected photons.

categories: quant-ph astro-ph physics.bio-ph physics.ins-det


title:
Some examples of vector bundles in the base locus of the generalized
  theta divisor

abstract:
  This paper shows that on the moduli space of semi-stable vector bundles of
fixed rank and determinant (of any degree) on a smooth curve of genus at least
two, the base locus of the generalized theta divisor is large provided the rank
is sufficiently large. It also shows that the base locus is large for positive
multiples of the theta divisor. This work extends results already known for the
case where the determinant is of degree zero.


title: On points at infinity of real spectra of polynomial rings

abstract:
  Let R be a real closed field and A=R[x_1,...,x_n]. Let sper A denote the real
spectrum of A. There are two kinds of points in sper A : finite points (those
for which all of |x_1|,...,|x_n| are bounded above by some constant in R) and
points at infinity. In this paper we study the structure of the set of points
at infinity of sper A and their associated valuations. Let T be a subset of
{1,...,n}. For j in {1,...,n}, let y_j=x_j if j is not in T and y_j=1/x_j if j
is in T. Let B_T=R[y_1,...,y_n]. We express sper A as a disjoint union of sets
of the form U_T and construct a homeomorphism of each of the sets U_T with a
subspace of the space of finite points of sper B_T. For each point d at
infinity in U_T, we describe the associated valuation v_{d*} of its image d* in
sper B_T in terms of the valuation v_d associated to d. Among other things we
show that the valuation v_{d*} is composed with v_d (in other words, the
valuation ring R_d is a localization of R_{d*} at a suitable prime ideal).


title:
Interaction of carbon clusters with Ni(100) : Application to the
  nucleation of carbon nanotubes

abstract:
  In order to understand the first stages of the nucleation of carbon nanotubes
in catalytic processes, we present a tight-binding Monte Carlo study of the
stability and cohesive mechanisms of different carbon structures deposited on
nickel (100) surfaces. Depending on the geometry, we obtain contrasted results.
On the one hand, the analysis of the local energy distributions of flat carbon
sheets, demonstrate that dangling bonds remain unsaturated in spite of the
presence of the metallic catalyst. Their adhesion results from the energy gain
of the surface Ni atoms located below the carbon nanostructure. On the other
hand, carbon caps are stabilized by the presence of carbon atoms occupying the
hollow sites of the fcc nickel structure suggesting the saturation of the
dangling bonds.


title: Isometries for the Caratheodory Metric

abstract:
  Under certain hypothesises, we prove that a map which is an isometry for the
Caratheodory infinitesimal metric at a point is an analytic isomorphism onto
its image.


title:
Hilbert Function and Betti Numbers of Algebras with Lefschetz Property
  of Order m

abstract:
  The authors T.Harima, J.C.Migliore, U.Nagel and J.Watanabe characterized the
Hilbert function of algbebras with the Lefschetz property. We extend this
characterization to algebras with the Lefschetz property m times. We also give
upper bounds for the Betti numbers of Artinian algebras with a given Hilbert
function and with the Lefschetz property m times and describe the cases in
which these bounds are reached.


title:
Crystal structure, Fermi surface calculations and Shubnikov-de Haas
  oscillations spectrum of the organic metal
  $\theta$-(BETS)$_4$HgBr$_4$(C$_6$H$_5$Cl) at low temperature

abstract:
  The organic metal \theta$-(BETS)$_4$HgBr$_4$(C$_6$H$_5$Cl) is known to
undergo a phase transition as the temperature is lowered down to about 240 K.
X-ray data obtained at 200 K indicate a corresponding modification of the
crystal structure, the symmetry of which is lowered from quadratic to
monoclinic. In addition, two different types of cation layers are observed in
the unit cell. The Fermi surface (FS), which can be regarded as a network of
compensated electron and hole orbits according to band structure calculations
at room temperature, turns to a set of two alternating linear chains of orbits
at low temperature. The field and temperature dependence of the Shubnikov-de
Haas oscillations spectrum have been studied up to 54 T. Eight frequencies are
observed which, in any case, points to a FS much more complex than predicted by
band structure calculations at room temperature, even though some of the
observed Fourier components might be ascribed to magnetic breakdown or
frequency mixing. The obtained spectrum could result from either an interaction
between the FS's linked to each of the two cation layers or to an eventual
additional phase transition in the temperature range below 200 K.


title: On Selberg's small eigenvalue conjecture and residual eigenvalues

abstract:
  We show that Selberg's eigenvalue conjecture concerning small eigenvalues of
the automorphic Laplacian for congruence groups is equivalent to a conjecture
about the non-existence of residual eigenvalues for a perturbed system. We
prove this using a combination of methods from asymptotic perturbation theory
and number theory.


title:
Wigner theorems for random matrices with dependent entries: Ensembles
  associated to symmetric spaces and sample covariance matrices

abstract:
  It is a classical result of Wigner that for an hermitian matrix with
independent entries on and above the diagonal, the mean empirical eigenvalue
distribution converges weakly to the semicircle law as matrix size tends to
infinity. In this paper, we prove analogs of Wigner's theorem for random
matrices taken from all infinitesimal versions of classical symmetric spaces.
This is a class of models which contains those studied by Wigner and Dyson,
along with seven others arising in condensed matter physics. Like Wigner's, our
results are universal in that they only depend on certain assumptions about the
moments of the matrix entries, but not on the specifics of their distributions.
What is more, we allow for a certain amount of dependence among the matrix
entries, in the spirit of a recent generalization of Wigner's theorem, due to
Schenker and Schulz-Baldes. As a byproduct, we obtain a universality result for
sample covariance matrices with dependent entries.


title:
UV Spectroscopy of Metal-Poor Massive Stars in the Small Magellanic
  Cloud

abstract:
  The Hubble Space Telescope has provided the first clear evidence for weaker
winds of metal-poor massive stars in the Small Magellanic Cloud, confirming
theoretical predictions of the metallicity dependence of mass-loss rates and
wind terminal velocities. For lower luminosity O-type stars however, derived
mass-loss rates are orders of magnitude lower than predicted, and are at
present unexplained.


title:
Quasielastic He atom scattering from surfaces: A stochastic description
  of the dynamics of interacting adsorbates

abstract:
  The study of diffusion and low frequency vibrational motions of particles on
metal surfaces is of paramount importance; it provides valuable information on
the nature of the adsorbate-substrate and the substrate-substrate interactions.
In particular, the experimental broadening observed in the diffusive peak with
increasing coverage is usually interpreted in terms of a dipole-dipole like
interaction among adsorbates via extensive molecular dynamics calculations
within the Langevin framework. Here we present an alternative way to interpret
this broadening by means of a purely stochastic description, namely the
interacting single adsorbate approximation, where two noise sources are
considered: (1) a Gaussian white noise accounting for the surface friction and
temperature, and (2) a white shot noise replacing the interaction potential
between adsorbates. Standard Langevin numerical simulations for flat and
corrugated surfaces (with a separable potential) illustrate the dynamics of Na
atoms on a Cu(100) surface which fit fairly well to the analytical expressions
issued from simple models (free particle and anharmonic oscillator) when the
Gaussian approximation is assumed. A similar broadening is also expected for
the frustrated translational mode peaks.


title:
Spinor moving frame, M0-brane covariant BRST quantization and intrinsic
  complexity of the pure spinor approach

abstract:
  To exhibit the possible origin of the inner complexity of the Berkovits's
pure spinor approach, we consider the covariant BRST quantization of the D=11
massless superparticle (M0-brane) in its spinor moving frame or twistor-like
Lorentz harmonics formulation. The presence of additional twistor-like
variables (spinor harmonics) allows us to separate covariantly the first and
the second class constraints. After taking into account the second class
constraints by means of Dirac brackets and after further reducing the first
class constraints algebra, the dynamical system is described by the cohomology
of a simple BRST charge associated to the d=1, n=16 supersymmetry algebra. The
calculation of the cohomology of this BRST operator requires a regularization
which implies the complexification of the bosonic ghost associated to the
kappa-symmetry and further leads to a complex (non-Hermitian) BRST charge which
is essentially the `pure spinor' BRST operator by Berkovits, but with a
composite pure spinor.


title:
Compatibility of quantization functors of Lie bialgebras with duality
  and doubling operations

abstract:
  We study the behavior of the Etingof-Kazhdan quantization functors under the
natural duality operations of Lie bialgebras and Hopf algebras. In particular,
we prove that these functors are "compatible with duality", i.e., they commute
with the operation of duality followed by replacing the coproduct by its
opposite. We then show that any quantization functor with this property also
commutes with the operation of taking doubles. As an application, we show that
the Etingof-Kazhdan quantization of some affine Lie superalgebras coincide with
their Drinfeld-Jimbo-type quantizations.


title: Lorentz transformation by mimicking the Lorentz transformation

abstract:
  We show that starting with the fact that special relativity theory is
concerned with a distortion of the observed length of a moving rod, without
mentioning if it is a "contraction" or "dilation", we can derive the Lorentz
transformations for the spacetime coordinates of the same event. This
derivation is based on expressing the length of the moving rod as a sum of
components with all the lengths involved in this summation being measured by
the observers of the same inertial reference frame.


title:
Detection of $1.6\times 10^{10}$ M$_\odot$ of molecular gas in the host
  galaxy of the $z=5.77$ SDSS quasar J0927+2001

abstract:
  We have detected emission by the CO 5-4 and 6-5 rotational transitions at $z
= 5.7722\pm 0.0006$ from the host galaxy of the SDSS quasar J0927+2001 using
the Plateau de Bure interferometer. The peak line flux density for the CO 5-4
line is $0.72 \pm 0.09$ mJy, with a line FWHM = $610 \pm 110$ km s$^{-1}$. The
implied molecular gas mass is $(1.6 \pm 0.3) \times 10^{10}$ M$_\odot$. We also
detect the 90 GHz continuum at $0.12 \pm 0.03$ mJy, consistent with a 47K dust
spectrum extrapolated from higher frequencies. J0927+2001 is the second example
of a huge molecular gas reservoir within the host galaxy of a quasar within 1
Gyr of the big bang. Observations of J0927+2001 are consistent with a massive
starburst coeval with a bright quasar phase in the galaxy, suggesting the rapid
formation of both a super-massive black hole through accretion, and the stellar
host spheroid, at a time close to the end of cosmic reionization.


title: Negative dependence and the geometry of polynomials

abstract:
  We introduce the class of {\em strongly Rayleigh} probability measures by
means of geometric properties of their generating polynomials that amount to
the stability of the latter. This class covers important models such as
determinantal measures (e.g. product measures, uniform random spanning tree
measures) and distributions for symmetric exclusion processes. We show that
strongly Rayleigh measures enjoy all virtues of negative dependence and we also
prove a series of conjectures due to Liggett, Pemantle, and Wagner,
respectively. Moreover, we extend Lyons' recent results on determinantal
measures and we construct counterexamples to several conjectures of Pemantle
and Wagner on negative dependence and ultra log-concave rank sequences.


title: A Cultural Market Model

abstract:
  Social interactions and personal tastes shape our consumption behavior of
cultural products. In this study, we present a computational model of a
cultural market and we aim to analyze the behavior of the consumer population
as an emergent phenomena. Our results suggest that the final market shares of
cultural products dramatically depend on consumer heterogeneity and social
interaction pressure. Furthermore, the relation between the resulting market
shares and social interaction is robust with respect to a wide range of
variation in the parameter values and the type of topology.


title: AGN counts at 15um. XMM observations of the ELAIS-S1-5 sample

abstract:
  Context: The counts of galaxies and AGN in the mid infra-red (MIR) bands are
important instruments for studying their cosmological evolution. However, the
classic spectral line ratios techniques can become misleading when trying to
properly separate AGN from starbursts or even from apparently normal galaxies.
  Aims: We use X-ray band observations to discriminate AGN activity in
previously classified MIR-selected starburst galaxies and to derive updated
AGN1 and (Compton thin) AGN2 counts at 15 um.
  Methods: XMM observations of the ELAIS-S1 15um sample down to flux limits
~2x10^-15 erg cm^-2 s^-1 (2-10 keV band) were used. We classified as AGN all
those MIR sources with a unabsorbed 2-10 keV X-ray luminosity higher that
~10^42 erg/s.
  Results: We find that at least about 13(+/-6) per cent of the previously
classified starburst galaxies harbor an AGN. According to these figures, we
provide an updated estimate of the counts of AGN1 and (Compton thin) AGN2 at 15
um. It turns out that at least 24% of the extragalactic sources brighter than
0.6 my at 15 um are AGN (~13% contribution to the extragalactic background
produced at fluxes brighter than 0.6 mJy).


title:
Dust-scattered X-ray halos around two Swift gamma-ray bursts: GRB 061019
  and GRB 070129

abstract:
  Two new expanding X-ray rings were detected by the Swift XRT instrument
during early follow-up observations of GRB 061019 and GRB 070129, increasing to
5 the number of dust scattering X-ray halos observed around GRBs. Although
these two halos were particularly faint, a sensitive analysis can be performed
that optimizes the method originally developed by Tiengo & Mereghetti (2006) to
analyze dust scattering rings observed with XMM-Newton for the Swift satellite.
In the case of GRB 061019, a known giant molecular cloud is identified as the
one responsible for the scattering process, and its distance is accurately
measured (d=940$\pm$40 pc) through the dynamics of the expanding ring. In the
second case, XRT observed both the main peak of the prompt emission of GRB
070129 and the scattering halo, but the small number of detected halo photons
prevents us from distinguish between different dust models.


title:
Magnetodipolar interlayer interaction effect on the magnetization
  dynamics of a trilayer square element with the Landau domain structure

abstract:
  We present a detailed numerical simulation study of the effects caused by the
magnetodipolar interaction between ferromagnetic (FM) layers of a trilayer
magnetic nanoelement on its magnetization dynamics. As an example we use a
Co/Cu/Ni80Fe20 element with a square lateral shape where the magnetization of
FM layers forms a closed Landau-like domain pattern. First we show that when
the thickness of the non-magnetic (NM) spacer is in the technology relevant
region h ~ 10 nm, magnetodipolar interaction between 90o Neel domain walls in
FM layers qualitatively changes the equilibrium magnetization state of these
layers. In the main of the paper we compare the magnetization dynamics induced
by a sub-nsec field pulse in a single-layer Ni80Fe20 (Py) element and in the
Co/Cu/Py trilayer element. Here we show that (i) due to the spontaneous
symmetry breaking of the Landau state in the FM/NM/FM trilayer its domains and
domain walls oscillate with different frequencies and have different spatial
oscillation patterns; (ii) magnetization oscillations of the trilayer domains
are strongly suppressed due to different oscillation frequencies of domains in
Co and Py; (iii) magnetization dynamics qualitatively depends on the relative
rotation sense of magnetization states in Co and Py layers and on the
magnetocrystalline anisotropy kind of Co crystallites. Finally we discuss the
relation of our findings with experimental observations of magnetization
dynamics in magnetic trilayers, performed using the element-specific
time-resolved X-ray microscopy.


title: Particularly Efficient Star Formation in M33

abstract:
  The Star Formation (SF) rate in galaxies is an important parameter at all
redshifts and evolutionary stages of galaxies. In order to understand the
increased SF rates in intermediate redshift galaxies one possibility is to
study star formation in local galaxies with properties frequently found at this
earlier epoch like low metallicity and small size. We present sensitive
observations of the molecular gas in M 33, a small Local Group spiral at a
distance of 840 kpc which shares many of the characteristics of the
intermediate redshift galaxies. The observations were carried out in the
CO(2--1) line with the HERA heterodyne array on the IRAM 30 m telescope. A
11\arcmin$\times$22\arcmin region in the northern part of M 33 was observed,
reaching a detection threshold of a few 10$^{3}$ \msol. The correlation in this
field between the CO emission and tracers of SF (8\mum, 24\mum, \Ha, FUV) is
excellent and CO is detected very far North, showing that molecular gas forms
far out in the disk even in a small spiral with a subsolar metallicity. One
major molecular cloud was discovered in an interarm region with no HI peak and
little if any signs of SF -- without a complete survey this cloud would never
have been found. The radial dependence of the CO emission has a scale length
similar to the dust emission, less extended than the \Ha or FUV. If, however,
the $\ratioo$ ratio varies inversely with metallicity, then the scale length of
the H$_2$ becomes similar to that of the \Ha or FUV. Comparing the SF rate to
the H$_2$ mass shows that M 33, like the intermediate redshift galaxies it
resembles, has a significantly higher SF efficiency than large local universe
spirals.


title: Hardy's theorem for the q-Bessel Fourier transform

abstract:
  In this paper we give a q-analogue of the Hardy's theorem for the $q$-Bessel
Fourier transform. The celebrated theorem asserts that if a function $f$ and
its Fourier transform $\hat{f}$ satisfying $|f(x)|\leq c.e^{-{1/2} x^2}$ and
$|\hat{f}(x)|\leq c.e^{-{1/2} x^2}$ for all $x\in\mathbb{% R}$ then
$f(x)=\text{const}.e^{-{1/2} x^2}$.


title:
Memory efficient scheduling of Strassen-Winograd's matrix multiplication
  algorithm

abstract:
  We propose several new schedules for Strassen-Winograd's matrix
multiplication algorithm, they reduce the extra memory allocation requirements
by three different means: by introducing a few pre-additions, by overwriting
the input matrices, or by using a first recursive level of classical
multiplication. In particular, we show two fully in-place schedules: one having
the same number of operations, if the input matrices can be overwritten; the
other one, slightly increasing the constant of the leading term of the
complexity, if the input matrices are read-only. Many of these schedules have
been found by an implementation of an exhaustive search algorithm based on a
pebble game.


title: Curve counting via stable pairs in the derived category

abstract:
  For a nonsingular projective 3-fold $X$, we define integer invariants
virtually enumerating pairs $(C,D)$ where $C\subset X$ is an embedded curve and
$D\subset C$ is a divisor. A virtual class is constructed on the associated
moduli space by viewing a pair as an object in the derived category of $X$. The
resulting invariants are conjecturally equivalent, after universal
transformations, to both the Gromov-Witten and DT theories of $X$. For
Calabi-Yau 3-folds, the latter equivalence should be viewed as a wall-crossing
formula in the derived category.
  Several calculations of the new invariants are carried out. In the Fano case,
the local contributions of nonsingular embedded curves are found. In the local
toric Calabi-Yau case, a completely new form of the topological vertex is
described.
  The virtual enumeration of pairs is closely related to the geometry
underlying the BPS state counts of Gopakumar and Vafa. We prove that our
integrality predictions for Gromov-Witten invariants agree with the BPS
integrality. Conversely, the BPS geometry imposes strong conditions on the
enumeration of pairs.


title: Surface polaritons on left-handed spheres

abstract:
  We consider the interaction of an electromagnetic field with a left-handed
sphere, i.e., with a sphere fabricated from a left-handed material, in the
framework of complex angular momentum techniques. We emphasize more
particularly, from a semiclassical point of view, the resonant aspects of the
problem linked to the existence of surface polaritons. We prove that the
long-lived resonant modes can be classified into distinct families, each family
being generated by one surface polariton propagating close to the sphere
surface and we physically describe all the surface polaritons by providing, for
each one, its dispersion relation and its damping. This can be achieved by
noting that each surface polariton corresponds to a particular Regge pole of
the electric part (TM) or the magnetic part (TE) of the $S$ matrix of the
sphere. Moreover, for both polarizations, we find that there exists a
particular surface polariton which corresponds, in the large radius limit, to
that supported by the plane interface. There also exists, for both
polarizations, an infinite family of surface polaritons of whispering gallery
type having no analogs in the plane interface case and specific to left-handed
materials. They present a "left-handed behavior" (phase and group velocities
are opposite) as well as a very weak damping. They could be very useful in the
context of plasmonics or cavity quantum electrodynamics.


title: A remarkable DG-module model for configuration spaces

abstract:
  Let M be a simply-connected closed manifold and consider the (ordered)
configuration space of $k$ points in M, F(M,k). In this paper we construct a
commutative differential graded algebra which is a potential candidate for a
model of the rational homotopy type of F(M,k). We prove that our model it is at
least a Sigma_k-equivariant differential graded model.
  We also study Lefschetz duality at the level of cochains and describe
equivariant models of the complement of a union of polyhedra in a closed
manifold.


title: Convection and AGN Feedback in Clusters of Galaxies

abstract:
  A number of studies have shown that the convective stability criterion for
the intracluster medium (ICM) is very different from the Schwarzchild criterion
due to the effects of anisotropic thermal conduction and cosmic rays. Building
on these studies, we develop a model of the ICM in which a central active
galactic nucleus (AGN) accretes hot intracluster plasma at the Bondi rate and
produces cosmic rays that cause the ICM to become convectively unstable. The
resulting convection heats the intracluster plasma and regulates its
temperature and density profiles. By adjusting a single parameter in the model
(the size of the cosmic-ray acceleration region), we are able to achieve a good
match to the observed density and temperature profiles in a sample of eight
clusters. Our results suggest that convection is an important process in
cluster cores. An interesting feature of our solutions is that the cooling rate
is more sharply peaked about the cluster center than is the convective heating
rate. As a result, in several of the clusters in our sample, a compact cooling
flow arises in the central region with a size R that is typically a few kpc.
The cooling flow matches onto a Bondi flow at smaller radii. The mass accretion
rate in the Bondi flow is equal to, and controlled by, the rate at which mass
flows in through the cooling flow. Our solutions suggest that the AGN regulates
the mass accretion rate in these clusters by controlling R: if the AGN power
rises above the equilibrium level, R decreases, the mass accretion rate drops,
and the AGN power drops back down to the equilibrium level.


title: From ballistic to diffusive behavior in periodic potentials

abstract:
  The long-time/large-scale, small-friction asymptotic for the one dimensional
Langevin equation with a periodic potential is studied in this paper. It is
shown that the Freidlin-Wentzell and central limit theorem (homogenization)
limits commute. We prove that, in the combined small friction,
long-time/large-scale limit the particle position converges weakly to a
Brownian motion with a singular diffusion coefficient which we compute
explicitly. We show that the same result is valid for a whole one parameter
family of space/time rescalings. The proofs of our main results are based on
some novel estimates on the resolvent of a hypoelliptic operator.


title:
Another proof for the equivalence between invariance of closed sets with
  respect to stochastic and deterministic systems

abstract:
  We provide a short and elementary proof for the recently proved result by G.
da Prato and H. Frankowska that -- under minimal assumptions -- a closed set is
invariant with respect to a stochastic control system if and only if it is
invariant with respect to the (associated) deterministic control system.


title: Critical velocity for superfluid flow across the BEC-BCS crossover

abstract:
  Critical velocities have been observed in an ultracold superfluid Fermi gas
throughout the BEC-BCS crossover. A pronounced peak of the critical velocity at
unitarity demonstrates that superfluidity is most robust for resonant atomic
interactions. Critical velocities were determined from the abrupt onset of
dissipation when the velocity of a moving one dimensional optical lattice was
varied. The dependence of the critical velocity on lattice depth and on the
inhomogeneous density profile was studied.


title:
Determination of the \eta\to\pi^+\pi^-\pi^0 Dalitz Plot slopes and
  asymmetries with the KLOE detector

abstract:
  We have studied, with the KLOE detector at the DA$\Phi$NE $\Phi$-Factory, the
dynamics of the decay $\eta\to\pi^+\pi^-\pi^0$ using data from the radiative
$\phi\to\eta\gamma$ decay for an integrated luminosity $L = 450
\textrm{pb^{-1}}$. From a fit to the Dalitz plot density distribution we obtain
a precise measurement of the slope parameters. This should allow to improve the
knowledge of the decay amplitude which is sensitive to the u-d quark mass
difference. We also present new best results on the C-violating asymmetries in
the $\eta\to\pi^+\pi^-\pi^0$ decay.


title:
Identified hadron spectra in Pb-Pb at sqrt(s) = 5.5 TeV:
  hydrodynamics+pQCD predictions

abstract:
  The single inclusive charged hadron pT spectra in Pb-Pb collisions at the
LHC, predicted by a combined hydrodynamics+perturbative QCD (pQCD) approach are
presented.


title:
Direct photon spectra in Pb-Pb at sqrt(s) = 5.5 TeV: hydrodynamics+pQCD
  predictions

abstract:
  The transverse momentum spectra for direct photons produced in Pb-Pb
collisions at the LHC, including thermal (hydrodynamics) and prompt (pQCD)
emissions are presented.


title: Exchange induced charge inhomogeneities in rippled neutral graphene

abstract:
  A new mechanism that induces charge density variations in corrugated graphene
is proposed. Here it is shown how the interplay between lattice deformations
and exchange interactions can induce charge separation, i.e., puddles of
electrons and holes, for realistic deformation values of the graphene sheet.
The induced charge density lies in the range of $10^{11}-10^{12}$ cm$^{-2}$,
which is compatible with recent measurements.


title:
Manufacturing a thin wire electrostatic trap (TWIST) for ultracold polar
  molecules

abstract:
  We present a detailed description on how to build a Thin WIre electroStatic
Trap (TWIST) for ultracold polar molecules. It is the first design of an
electrostatic trap that can be superimposed directly onto a magneto optical
trap (MOT). We can thus continuously produce ultracold polar molecules via
photoassociation from a two species MOT and instantaneously trap them in the
TWIST without the need for complex transfer schemes. Despite the spatial
overlap of the TWIST and the MOT, the two traps can be operated and optimized
completely independently due to the complementary nature of the utilized
trapping mechanisms.


title: Order Independence in Asynchronous Cellular Automata

abstract:
  A sequential dynamical system, or SDS, consists of an undirected graph Y, a
vertex-indexed list of local functions F_Y, and a permutation pi of the vertex
set (or more generally, a word w over the vertex set) that describes the order
in which these local functions are to be applied. In this article we
investigate the special case where Y is a circular graph with n vertices and
all of the local functions are identical. The 256 possible local functions are
known as Wolfram rules and the resulting sequential dynamical systems are
called finite asynchronous elementary cellular automata, or ACAs, since they
resemble classical elementary cellular automata, but with the important
distinction that the vertex functions are applied sequentially rather than in
parallel. An ACA is said to be pi-independent if the set of periodic states
does not depend on the choice of pi, and our main result is that for all n>3
exactly 104 of the 256 Wolfram rules give rise to a pi-independent ACA. In 2005
Hansson, Mortveit and Reidys classified the 11 symmetric Wolfram rules with
this property. In addition to reproving and extending this earlier result, our
proofs of pi-independence also provide significant insight into the dynamics of
these systems.


title:
The SDSS-GALEX viewpoint of the truncated red sequence in field
  environments at z~0

abstract:
  We combine GALEX near-UV photometry with a volume-limited sample of local
(0.005<z<0.037) SDSS DR4 galaxies to examine the composition and the
environmental dependencies of the optical and UV-optical colour-magnitude (C-M)
diagrams. We find that ~30% of red sequence galaxies in the optical C-M diagram
show signs of ongoing star-formation from their spectra having EW(Halpha)>2A.
This contamination is greatest at faint magnitudes (Mr>-19) and in field
regions where as many as three-quarters of red sequence galaxies are
star-forming, and as such has important consequences for following the build-up
of the red sequence. We find that the NUV-r colour instead allows a much more
robust separation of passively-evolving and star-forming galaxies, which allows
the build-up of the UV-selected red sequence with redshift and environment to
be directly interpreted in terms of the assembly of stellar mass in
passively-evolving galaxies. We find that in isolated field regions the number
density of UV-optical red sequence galaxies declines rapidly at magnitudes
fainter than Mr~-19 and appears completely truncated at Mr~-18. This confirms
the findings of Haines et al. (2007) that no passively-evolving dwarf galaxies
are found more than two virial radii from a massive halo, whether that be a
group, cluster or massive galaxy. These results support the downsizing paradigm
whereby the red sequence is assembled from the top down, being already largely
in place at the bright end by z~1, and the faint end filled in at later epochs
in clusters and groups through environment-related processes such as
ram-pressure stripping or galaxy harassment.


title:
Search for chargino-neutralino production in ppbar collisions at sqrt(s)
  = 1.96 TeV

abstract:
  We present the results of a search for associated production of the chargino
and neutralino supersymmetric particles using up to 1.1 fb-1 of integrated
luminosity collected by the CDF II experiment at the Tevatron ppbar collider at
a center-of-mass energy of 1.96 TeV. The search is conducted by analyzing
events with a large transverse momentum imbalance and either three charged
leptons or two charged leptons of the same electric charge. The numbers of
observed events are found to be consistent with standard model expectations.
Upper limits on the production cross section are derived in different
theoretical models. In one of these models a lower limit on the mass of the
chargino is set at 129 GeV/c^2 at the 95% confidence level.


title: A proof of the multiplicity one conjecture for GL(n) in GL(n+1)

abstract:
  Let F be a non-archimedean local field of characteristic zero. We consider
distributions on GL(n+1,F) which are invariant under the adjoint action of
GL(n,F). We prove that any such distribution is invariant with respect to
transposition. This implies that the restriction to GL(n) of any irreducible
smooth representation of GL(n+1) is multiplicity free.
  Our paper is based on the recent work [RS] of Steve Rallis and Gerard
Schiffmann where they made a remarkable progress on this problem.
  In [RS], they also show that our result implies multiplicity one theorem for
restrictions from the orthogonal group $O(V \oplus F)$ to $O(V)$.


title: The origin of strong correlations and superconductivity in Na$_x$CoO$_2$

abstract:
  We propose a minimal model resolving a puzzle of enigmatic correlations
observed in sodium-rich Na$_x$CoO$_2$ where one expects a simple, free motion
of the dilute $S=1/2$ holes doped into a band insulator NaCoO$_2$. The model
also predicts singlet superconductivity at experimentally observed
compositions. The model is based on a key property of cobalt oxides -- the
spin-state quasidegeneracy of CoO$_6$ octahedral complex -- leading to an
unusual physics of, {\it e.g.}, LaCoO$_3$. We show that correlated hopping
between $t_{2g}$ and $e_g$ states leads to the spin-polaron physics at $x\sim
1$, and to an extended s-wave pairing at larger doping when coherent fermionic
bands are formed.


title:
Weights of modular forms on $\mathrm{SO}^{+}(2,l)$ and congruences
  between Eisenstein series and cusp forms of half-integral weight on
  $\mathrm{SL}_{2}$

abstract:
  Let $E$ be a level 1, vector valued Eisenstein series of half-integral
weight, normalized so that the coefficients are all in $\mathbb{Z}$. We show
that there is a level one vector valued cusp form $f$ with the same weight as
$E$ and with coefficients in $\mathbb{Z}$, which is congruent to $E$ modulo the
constant term of $E$.


title: Study of star formation in NGC 1084

abstract:
  We present UBVRI broad band, H$\alpha$ narrow band photometry of the star
forming complexes in the infra-red bright galaxy NGC 1084. Results of medium
resolution spectroscopy of some of the brighter complexes are also discussed.
Spectroscopic data is used to better estimate the internal reddening within the
galaxy which is found to be highly variable and to calculate metallicity which
is close to the solar value. Diagnostic diagram identifies the shocked regions
within this galaxy. The narrow band H$\alpha$ flux and its equivalent width are
used to determine the star formation rates of the complexes and the
distribution of ages. Star formation rates for a few of the complexes are found
to be as high as 0.5 $M_{\odot}$/year. The star forming complexes lie in the
age range 3 Myr to 6.5 Myr. U-B vs V-I colour-colour mixed population model
created using the Starburst99 model colours is used to estimate the ages of the
stellar populations present within these regions. Using this technique, it is
found that the star formation in NGC 1084 has taken place in a series of short
bursts over the last 40 Myr or so. It is proposed that the likely trigger for
enhanced star formation is merger with a gas rich dwarf galaxy.


title:
Rectification by charging -- the physics of contact-induced current
  asymmetry in molecular conductors

abstract:
  We outline the qualitatively different physics behind charging-induced
current asymmetries in molecular conductors operating in the weakly interacting
self-consistent field (SCF) and the strongly interacting Coulomb Blockade (CB)
regimes. A conductance asymmetry arises in SCF because of the unequal
mean-field potentials that shift a closed-shell conducting level differently
for positive and negative bias. A very different current asymmetry arises for
CB due to the unequal number of open-shell excitation channels at opposite bias
voltages. The CB regime, dominated by single charge effects, typically requires
a computationally demanding many-electron or Fock space description. However,
our analysis of molecular Coulomb Blockade measurements reveals that many novel
signatures can be explained using a {{simpler}} orthodox model that involves an
incoherent sum of Fock space excitations and {\it{hence treats the molecule as
a metallic dot or an island}}. This also reduces the complexity of the Fock
space description by just including various charge configurations only, thus
partially underscoring the importance of electronic structure, while retaining
the essence of the single charge nature of the transport process. We finally
point out, however, that the inclusion of electronic structure and hence
well-resolved Fock space excitations is crucial in some notable examples.


title: New Ultraviolet Observations of AM CVn

abstract:
  We have obtained observations of the ultraviolet spectrum of AM CVn, an
ultra-short-period helium cataclysmic variable, using the Space Telescope
Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST). We
obtained data in time-tag mode during two consecutive orbits of HST, covering
1600-3150 and 1140-1710 Angstrom, respectively. The mean spectrum is
approximately flat in f-nu. The absorption profiles of the strong lines of N V,
Si IV, C IV, He II, and N IV are blue-shifted and in some cases asymmetric,
evidencing a wind that is partly occulted by the accretion disk. There is weak
red-shifted emission from N V and He II. The profiles of these lines vary
mildly with time. The light curve shows a decline of ~20% over the span of the
observations. There is also flickering and a 27 s (or 54 s) "dwarf nova
oscillation", revealed in a power-spectrum analysis. The amplitude of this
oscillation is larger at shorter wavelengths. We assemble and illustrate the
spectral energy distribution (s.e.d.) of AM CVn from the ultraviolet to the
near-infrared. Modeling the accretion phenomenon in this binary system can in
principle lead to a robust estimate of the mass accretion rate on to the
central white dwarf, which is of great interest in characterizing the
evolutionary history of the binary system. Inferences about the mass accretion
rate depend strongly on the local radiative properties of the disk, as we
illustrate. Uncertainty in the distance of AM CVn and other parameters of the
binary system presently limit the ability to confidently infer the mass
accretion rate.


title: Radio Loudness of AGNs: Host Galaxy Morphology and the Spin Paradigm

abstract:
  We investigate how the total radio luminosity of AGN-powered radio sources
depends on their accretion luminosity and the central black hole mass. We find
that AGNs form two distinct and well separated sequences on the radio-loudness
- Eddington-ratio plane. We argue that these sequences mark the real upper
bounds of radio-loudness of two distinct populations of AGNs: those hosted
respectively by elliptical and disk galaxies. Both sequences show the same
dependence of the radio-loudness on the Eddington ratio (an increase with
decreasing Eddington ratio), which suggests that another parameter in addition
to the accretion rate must play a role in determining the jet production
efficiency in active galactic nuclei, and that this parameter is related to
properties of the host galaxy. The revealed host-related radio dichotomy breaks
down at high accretion rates where the dominant fraction of luminous quasars
hosted by elliptical galaxies is radio quiet. We argue that the huge difference
between the radio-loudness reachable by AGNs in disc and elliptical galaxies
can be explained by the scenario according to which the spin of a black hole
determines the outflow's power, and central black holes can reach large spins
only in early type galaxies (following major mergers), and not (in a
statistical sense) in spiral galaxies.


title: Temperature Equilibration Rate with Fermi-Dirac Statistics

abstract:
  We calculate the electron-ion temperature equilibration rate in a fully
ionized, weakly to moderately coupled plasma, using an exact treatment of the
Fermi-Dirac electrons. The temperature is sufficiently high so that the
quantum-mechanical Born approximation to the scattering is valid. At the heart
of this calculation lies the method of dimensional continuation, a technique
that we borrow from quantum field theory and use in a novel fashion to regulate
the kinetic equations in a consistent manner. We can then perform a systematic
perturbation expansion and thereby obtain a finite first-principles result to
leading and next-to-leading order. Unlike model building, this systematic
calculation yields an estimate of its own error and thus prescribes its domain
of applicability. The calculational error is small for a weakly to moderately
coupled plasma, for which our result is nearly exact. It should also be
emphasized that our calculation becomes unreliable for a strongly coupled
plasma, where the perturbative expansion that we employ breaks down, and one
must then utilize model building and computer simulations. Besides providing
new and potentially useful results, we use this calculation as an opportunity
to explain the method of dimensional continuation in a pedagogical fashion.
Interestingly, in the regime of relevance for many inertial confinement fusion
experiments, the degeneracy corrections are comparable in size to the
subleading quantum correction below the Born approximation. For consistency, we
therefore present this subleading quantum-to-classical transition correction in
addition to the degeneracy correction.


title: I Zw 18 revisited with HST/ACS and Cepheids: New Distance and Age

abstract:
  We present new V and I-band HST/ACS photometry of I Zw 18, the most
metal-poor blue compact dwarf (BCD) galaxy in the nearby universe. It has been
argued in the past that I Zw 18 is a very young system that started forming
stars only < 500 Myr ago, but other work has hinted that older (> 1 Gyr) red
giant branch (RGB) stars may also exist. Our new data, once combined with
archival HST/ACS data, provide a deep and uncontaminated optical
color-magnitude diagram (CMD) that now strongly indicates an RGB. The RGB tip
(TRGB) magnitude yields a distance modulus (m-M)_0 = 31.30 +/- 0.17, i.e., D =
18.2 +/- 1.5 Mpc. The time-series nature of our observations allows us to also
detect and characterize for the first time three classical Cepheids in I~Zw~18.
The time-averaged Cepheid <V> and <I> magnitudes are compared to the VI
reddening-free Wesenheit relation predicted from new non-linear pulsation
models specifically calculated at the metallicity of I Zw 18. For the one
bona-fide classical Cepheid with a period of 8.63 days this implies a distance
modulus (m-M)_0 = 31.42 +/- 0.26. The other two Cepheids have unusually long
periods (125.0 and 129.8 d) but are consistent with this distance. The coherent
picture that emerges is that I Zw 18 is older and farther away than previously
believed. This rules out the possibility that I Zw 18 is a truly primordial
galaxy formed recently (z < 0.1) in the local universe.


title: Importance of bath dynamics for decoherence in spin systems

abstract:
  We study the decoherence of two coupled spins that interact with a chaotic
spin-bath environment. It is shown that connectivity of spins in the bath is of
crucial importance for the decoherence of the central system. The previously
found phenomenon of two-step decoherence (Phys. Rev. Lett. {\bf 90}, 210401
(2003)) turns out to be typical for the bath with a slow enough dynamics or no
dynamics. For a generic random system with chaotic dynamics a conventional
exponential relaxation to the pointer states takes place. Our results confirm a
conjecture of Paz and Zurek (Phys. Rev. Lett. {\bf 82}, 5181 (1999)) that for
weak enough interactions the pointer states are eigenstates of the central
system.


title: NNLO QCD predictions for the H -> WW -> l l nu nu signal at the LHC

abstract:
  We present a first computation of the NNLO QCD cross section at the LHC for
the production of four leptons from a Higgs boson decaying into W bosons. We
study the cross section for a Higgs boson mass Mh = 165 GeV; around this value
a Standard Model Higgs boson decays almost exclusively into W-pairs. We apply
all nominal experimental cuts on the final state leptons and the associated jet
activity and study the magnitude of higher-order effects up to NNLO on all
kinematic variables which are constrained by experimental cuts. We find that
the magnitude of the higher-order corrections varies significantly with the
signal selection cuts. As a main result we give the value of the cross section
at NNLO with all selection cuts envisaged for the search for the Higgs boson.


title: Search for Exclusive Gamma Gamma Production in Hadron-Hadron Collisions

abstract:
  We have searched for exclusive 2-photon production in proton-antiproton
collisions at sqrt{s} = 1.96 TeV, using 532/pb of integrated luminosity taken
by the Run II Collider Detector at Fermilab. The event signature requires two
electromagnetic showers, each with transverse energy E_T > 5 GeV and
pseudorapidity |eta|<1.0, with no other particles detected in the event. Three
candidate events are observed. We discuss the consistency of the three events
with gamma-gamma, pi0-pi0, or eta-eta production. The probability that other
processes fluctuate to 3 events or more is 1.7x10^-4. An upper limit on the
cross section of p+pbar --> p+gamma-gamma+pbar is set at 410 fb with 95%
confidence level.


title:
Pion Production by Protons on a Thin Beryllium Target at 6.4, 12.3, and
  17.5 GeV/c Incident Proton Momenta

abstract:
  An analysis of inclusive pion production in proton-beryllium collisions at
6.4, 12.3, and 17.5 GeV/c proton beam momentum has been performed. The data
were taken by Experiment 910 at the Alternating Gradient Synchrotron at the
Brookhaven National Laboratory. The differential $\pi^+$ and $\pi^-$ production
cross sections ($d^2\sigma/dpd\Omega$) are measured up to 400 mRad in
$\theta_{\pi}$ and up to 6 GeV/c in $p_{\pi}$. The measured cross section is
fit with a Sanford-Wang parameterization.