title:
Finite Difference Methods for Second Order in Space, First Order in Time
  Hyperbolic Systems and the Linear Shifted Wave Equation as a Model Problem in
  Numerical Relativity

abstract:
  Motivated by the problem of solving the Einstein equations, we discuss high
order finite difference discretizations of first order in time, second order in
space hyperbolic systems.Particular attention is paid to the case when first
order derivatives that can be identified with advection terms are approximated
with non-centered finite difference operators.We first derive general
properties of these discrete operators, then we extend a known result on
numerical stability for such systems to general order of accuracy.As an
application we analyze the shifted wave equation, including the behavior of the
numerical phase and group speeds at different orders of approximations. Special
attention is paid to when the use of off-centered schemes improves the accuracy
over the centered schemes.


title: Antiphase Synchronization in Environmentally coupled Rossler Oscillators

abstract:
  We study the manifestation of antiphase synchronization in a system of n
Rossler Oscillators coupled through a dynamic environment. When the feedback
from system to environment is positive (negative) and that from environment to
system is negative (positive), the oscillators enter into a state of anti phase
synchronization both in periodic and chaotic regimes. Their phases are found to
be uniformly distributed over 2$pi$, with a phase lag of 2$pi$ /n between
neighbors as is evident from the similarity function and the phase plots. The
transition to anti phase synchronization is marked by the crossover of (n-1)
zero Lyapunov Exponents to negative values. If the systems are individually in
chaotic phase, with strong enough coupling they end up in periodic states which
are in antiphase synchronization


title: Semiring Properties of Heyting Algebras

abstract:
  The relationship between Heyting algebras (HA) and semirings is explored. A
new class of HAs called Symmetric Heyting algebras (SHAs) is proposed, and a
necessary condition on SHAs to be consider semirings is given. We define a new
mathematical family called Heyting structures, which are similar to semirings,
but with Heyting-algebra operators in place of the usual arithmetic operators
usually seen in semirings. The impact of the zero-sum free property of
semirings on Heyting structures is shown as also the condition under which it
is possible to extend one Heyting structure to another. It is also shown that
the union of two or more sets forming Heyting structures is again a Heyting
structure, if the operators on the new structure are suitably derived from
those of the component structures. The analysis also provides a sufficient
condition such that the larger Heyting structure satisfying a monotony law
implies that the ones forming the union do so as well.


title:
Modification of Heisenberg uncertainty relations in non-commutative
  Snyder space-time geometry

abstract:
  We show that the Euclidean Snyder non-commutative space implies infinitely
many different physical predictions. The distinct frameworks are specified by
generalized uncertainty relations underlying deformed Heisenberg algebras.
Considering the one-dimensional case in the minisuperspace arena, the bouncing
Universe dynamics of loop quantum cosmology can be recovered.


title: Application of the New Form of the Semiclassical Quantization Condition

abstract:
  We demonstrate how a certain new form of the quantization condition proposed
earlier can be used outside the class of potentials for which this form ensures
exact spectra. Taking this form as a base we get an improved interpolating
condition for the potential wells with coinciding an + and - infinities
asymptotical values. Accuracy of the above conditions is discussed.


title:
Experimental demonstration of the stability of Berry's phase for a
  spin-1/2 particle

abstract:
  The geometric phase has been proposed as a candidate for noise resilient
coherent manipulation of fragile quantum systems. Since it is determined only
by the path of the quantum state, the presence of noise fluctuations affects
the geometric phase in a different way than the dynamical phase. We have
experimentally tested the robustness of Berry's geometric phase for spin-1/2
particles in a cyclically varying magnetic field. Using trapped polarized
ultra-cold neutrons it is demonstrated that the geometric phase contributions
to dephasing due to adiabatic field fluctuations vanish for long evolution
times.


title: On Kummer 3-folds

abstract:
  We investigate a generalization of Kummer construction, as introduced in a
recent paper by M. Andreatta and J.A. Wisniewski. The aim of this work is to
classify 3-dimensional Kummer varieties by computing their Poincare
polynomials.


title:
Hamiltonian description of radiation phenomena: Trautman-Bondi energy
  and corner conditions

abstract:
  Cauchy initial value problem on a hyperboloid is proved to define a
Hamiltonian system, provided the radiation data at null infinity are also taken
into account, as a part of Cauchy data. The "Trautman-Bondi mass", supplemented
by the "already radiated energy" assigned to radiation data, plays role of the
Hamiltonian function. This approach leads to correct description of the corner
conditions.


title: Mixing-induced activity in open flows

abstract:
  We develop a theory describing how a convectively unstable active field in an
open flow is transformed into absolutely unstable by local mixing. Presenting
the mixing region as one with a locally enhanced effective diffusion allows us
to find the linear transition point to an unstable global mode analytically. We
derive the critical exponent that characterizes weakly nonlinear regimes beyond
the instability threshold and compare it with numerical simulations of a full
two-dimensional flow problem. The obtained scaling law turns out to be
universal as it depends neither on geometry nor on the nature of the mixing
region.


title:
Covariant Field Equations, Gauge Fields and Conservation Laws from
  Yang-Mills Matrix Models

abstract:
  The effective geometry and the gravitational coupling of nonabelian gauge and
scalar fields on generic NC branes in Yang-Mills matrix models is determined.
Covariant field equations are derived from the basic matrix equations of
motions, known as Yang-Mills algebra. Remarkably, the equations of motion for
the Poisson structure and for the nonabelian gauge fields follow from a matrix
Noether theorem, and are therefore protected from quantum corrections. This
provides a transparent derivation and generalization of the effective action
governing the SU(n) gauge fields obtained in [1], including the would-be
topological term. In particular, the IKKT matrix model is capable of describing
4-dimensional NC space-times with a general effective metric. Metric
deformations of flat Moyal-Weyl space are briefly discussed.


title:
Simultaneous H.E.S.S. and Chandra observations of Sagittarius A* during
  an X-ray flare

abstract:
  The rapidly varying (~10 minute timescale) non-thermal X-ray emission
observed from Sgr A* implies that particle acceleration is occuring close to
the event horizon of the supermassive black hole. The TeV gamma-ray source HESS
J1745-290 is coincident with Sgr A* and may be closely related to its X-ray
emission. Simultaneous X-ray and TeV observations are required to elucidate the
relationship between these objects. We report on joint H.E.S.S./Chandra
observations performed in July 2005, during which an X-ray flare was detected.
Despite a factor of 9 increase in the X-ray flux of Sgr A*, no evidence is
found for an increase in the TeV gamma-ray flux from this region. We find that
an increase in the gamma-ray flux of a factor of 2 or greater can be excluded
at a confidence level of 99%. This finding disfavours scenarios in which the
keV and TeV emission are associated with the same population of accelerated
particles and in which the bulk of the gamma-ray emission is produced within
~10^{14} cm (~100 R_S) of the supermassive black hole.


title:
Quantum Monte Carlo study on speckle variation due to photorelaxation of
  ferroelectric clusters in paraelectric barium titanate

abstract:
  Time-dependent speckle pattern of paraelectric barium titanate observed in a
soft x-ray laser pump-probe measurement is theoretically investigated as a
correlated optical response to the pump and probe pulses. The scattering
probability is calculated based on a model with coupled soft x-ray photon and
ferroelectric phonon mode. It is found that the speckle variation is related
with the relaxation dynamics of ferroelectric clusters created by the pump
pulse. Additionally, critical slowing down of cluster relaxation arises on
decreasing temperature towards the paraelectric-ferroelectric transition
temperature. Relation between critical slowing down, local dipole fluctuation
and crystal structure are revealed by quantum Monte Carlo simulation.


title:
Fractional quantum Hall states with negative flux: edge modes in some
  Abelian and non-Abelian cases

abstract:
  We investigate the structure of gapless edge modes propagating at the
boundary of some fractional quantum Hall states. We show how to deduce explicit
trial wavefunctions from the knowledge of the effective theory governing the
edge modes. In general quantum Hall states have many edge states. Here we
discuss the case of fractions having only two such modes. The case of
spin-polarized and spin-singlet states at filling fraction 2/5 is considered.
We give an explicit description of the decoupled charged and neutral modes.
Then we discuss the situation involving negative flux acting on the composite
fermions. This happens notably for the filling factor 2/3 which supports two
counterpropagating modes. Microscopic wavefunctions for spin-polarized and
spin-singlet states at this filling factor are given. Finally we present an
analysis of the edge structure of a non-Abelian state involving also negative
flux. Counterpropagating modes involve in all cases explicit derivative
operators diminishing the angular momentum of the system.


title: The duration problem with multiple exchanges

abstract:
  We treat a version of the multiple-choice secretary problem called the
multiple-choice duration problem, in which the objective is to maximize the
time of possession of relatively best objects. It is shown that, for the
$m$--choice duration problem, there exists a sequence (s1,s2,...,sm) of
critical numbers such that, whenever there remain k choices yet to be made,
then the optimal strategy immediately selects a relatively best object if it
appears at or after time $s_k$ ($1\leq k\leq m$). We also exhibit an
equivalence between the duration problem and the classical best-choice
secretary problem. A simple recursive formula is given for calculating the
critical numbers when the number of objects tends to infinity. Extensions are
made to models involving an acquisition or replacement cost.


title: Collapse and Revival of `Schr\"odinger Cat' States

abstract:
  We study the dynamics of the Jaynes-Cummings Model for an array of $N_q$ two
level systems (or qubits) interacting with a quantized single mode
electromagnetic cavity (or quantum bus). For an initial cavity coherent state
$| \alpha >$ and the qubit system in a specified `basin of attraction' in its
Hilbert space, we demonstrate the oscillation of a superposition of two
macroscopic quantum states between the qubit system and the field mode. From
the perspective of either the qubit or the field system, there is collapse and
revival of a `Schr\"odinger Cat' state.


title: Cold atoms in double-well optical lattices

abstract:
  Cold atoms, loaded into an optical lattice with double-well sites, are
considered. Pseudospin representation for an effective Hamiltonian is derived.
The system in equilibrium displays two phases, ordered and disordered. The
second-order phase transition between the phases can be driven either by
temperature or by changing the system parameters. Collective pseudospin
excitations have a gap disappearing at the phase-transition point. Dynamics of
atoms is studied, when they are loaded into the lattice in an initially
nonequilibrium state. It is shown that the temporal evolution of atoms,
contrary to their equilibrium thermodynamics, cannot be described in the
mean-field approximation, since it results in a structurally unstable dynamical
system, but a more accurate description is necessary taking account of
attenuation effects.


title: Ballistic Intrinsic Spin-Hall Effect in HgTe Nanostructures

abstract:
  We report the first electrical manipulation and detection of the mesoscopic
intrinsic spin-Hall effect (ISHE) in semiconductors through non-local
electrical measurement in nano-scale H-shaped structures built on high mobility
HgTe/HgCdTe quantum wells. By controlling the strength of the spin-orbit
splittings and the n-type to p-type transition by a top-gate, we observe a
large non-local resistance signal due to the ISHE in the p-regime, of the order
of kOhms, which is several orders of magnitude larger than in metals. In the
n-regime, as predicted by theory, the signal is at least an order of magnitude
smaller. We verify our experimental observation by quantum transport
calculations which show quantitative agreement with the experiments.


title:
Chemical evolution of high-mass stars in close binaries. I. The
  eclipsing binary V453 Cygni

abstract:
  The eclipsing and double-lined spectroscopic binary system V453 Cygni
consists of two early B-type stars, one of which is nearing the terminal age
main sequence and one which is roughly halfway through its main sequence
lifetime. Accurate measurements of the masses and radii of the two stars are
available, which makes a detailed abundance analysis both more interesting and
more precise than for isolated stars. We have reconstructed the spectra of the
individual components of V453 Cyg from the observed composite spectra using the
technique of spectral disentangling. From these disentangled spectra we have
obtained improved effective temperature measurements of 27900 +/- 400 K and
26200 +/- 500 K, for the primary and secondary stars respectively, by fitting
non-LTE theoretical line profiles to the hydrogen Balmer lines. Armed with
these high-precision effective temperatures and the accurately known surface
gravities of the stars we have obtained the abundances of helium and metallic
elements. A detailed abundance analysis of the primary star shows a normal
(solar) helium abundance if the microturbulence velocity derived from metallic
lines is used. The elemental abundances show no indication that CNO-processed
material is present in the photosphere of this high-mass terminal age main
sequence star. The elemental abundances of the secondary star were derived by
differential study against a template spectrum of a star with similar
characteristics. Both the primary and secondary components display elemental
abundances which are in the ranges observed in the Galactic OB stars.


title: Area laws and entanglement distillability of thermal states

abstract:
  We study the entanglement distillability properties of thermal states of
many-body systems. Following the ideas presented in [D.Cavalcanti et al.,
arxiv:0705.3762], we first discuss the appearance of bound entanglement in
those systems satisfying an entanglement area law. Then, we extend these
results to other topologies, not necessarily satisfying an entanglement area
law. We also study whether bound entanglement survives in the macroscopic limit
of an infinite number of particles.


title: Canonical quantization of motion on submanifolds

abstract:
  This is an extended version of the talk given by the Author at the 40th
Symposium on Mathematical Physics held in Torun, Poland, June 25-28, 2008. We
review the methods of canonical quantization of free particle motion on curved
submanifolds considered as a system with second class constraints. The work is
based on our previous articles, quant-ph/0508044 and quant-ph/0508111. However,
some new results are also presented.


title: Teleportation via maximally and non-maximally entangled mixed states

abstract:
  We study the efficacy of two-qubit mixed entangled states as resources for
quantum teleportation. We first consider two maximally entangled mixed states,
viz., the Werner state\cite{werner}, and a class of states introduced by Munro
{\it et al.} \cite{munro}. We show that the Werner state when used as
teleportation channel, gives rise to better average teleportation fidelity
compared to the latter class of states for any finite value of mixedness. We
then introduce a non-maximally entangled mixed state obtained as a convex
combination of a two-qubit entangled mixed state and a two-qubit separable
mixed state. It is shown that such a teleportation channel can outperform
another non-maximally entangled channed, viz., the Werner derivative for a
certain range of mixedness. Further, there exists a range of parameter values
where the former state satisfies a Bell-CHSH type inequality and still performs
better as a teleportation channel compared to the Werner derivative even though
the latter violates the inequality.


title:
A limit transition from the Heckman-Opdam hypergeometric functions to
  the Whittaker functions associated with root systems

abstract:
  We prove that the radial part of the class one Whittaker function on a split
semisimple Lie group can be obtained as an appropriate limit of the
Heckman-Opdam hypergeometric function.


title:
Josephson-current induced conformational switching of a molecular
  quantum dot

abstract:
  We discuss the behavior of a two-level system coupled to a quantum dot
contacted by superconducting source/drain electrodes, representing a simple
model for the conformational degree of freedom of a molecular dot or a break
junction. The Josephson current is shown to induce conformational changes,
including a complete reversal. For small bias voltage, periodic conformational
motions induced by Landau-Zener transitions between Andreev states are
predicted.


title:
Measurement of D+- and D0 production in deep inelastic scattering using
  a lifetime tag at HERA

abstract:
  The production of D+- and D0 mesons has been measured with the ZEUS detector
at HERA using an integrated luminosity of 133.6 pb-1. The measurements cover
the kinematic range 5 < Q^2 < 1000 GeV^2, 0.02 < y < 0.7, 1.5 < p_T^D < 15 GeV
and eta^D < 1.6. Combinatorial background to the D meson signals is reduced by
using the ZEUS microvertex detector to reconstruct displaced secondary
vertices. Production cross sections are compared with the predictions of
next-to-leading-order QCD which is found to describe the data well.
Measurements are extrapolated to the full kinematic phase space in order to
obtain the open-charm contribution, F2^ccbar, to the proton structure function,
F2.


title:
Solutions to some Molecular Potentials in D-Dimensions: Asymptotic
  Iteration Method

abstract:
  We give a study of some molecular vibration potentials by solving the
D-dimensional Schrodinger equation using the asymptotic iteration method (AIM).
The eigenvalue values obtained by the AIM are found to agree with analytic
solutions. The corresponding eigenfunctions are also obtained using the AIM


title: Quasi-complete homogeneous contact manifold associated to a cubic form

abstract:
  Starting from a cubic form, we give a general construction of a
quasi-complete homogeneous manifold endowed with a natural contact structure.
We show that it can be compactified into a projective contact manifold if and
only if the cubic form is the determinant of a simple cubic Jordan algebra.


title:
Transition from mode-locked periodic orbit to chaos in a 2D piecewise
  smooth non-invertible map

abstract:
  In this work we report a new route to chaos from a resonance torus in a
piecewise smooth non-invertible map of the plane into itself. The closed
invariant curve defining the resonance torus is formed by the union of unstable
manifolds of saddle cycle and the points of stable cycle and saddle cycle. We
have found that a cusp torus cannot develop before the onset of chaos, though
the loop torus appears. The destruction of the two-dimensional torus occurs
through homoclinic bifurcation in the presence of an infinite number of loops
on the invariant curve. We show that owing to the non-invertible nature of the
map, the structure of the basin of attraction changes from simply connected to
a nonconnected one. We also describe how the mechanism of transition to chaos
differs from the scenario of appearance of chaos in invertible maps as well as
in smooth non-invertible maps.


title:
Overdetermined 2D Systems Invariant in One Direction and Their Transfer
  Functions

abstract:
  In this work we develop a theory of Vessels. This object arises in the study
of overdetermined 2D systems invariant in one of the variables, which are
usually called time invariant. To each overdetermined time invariant 2D systems
there is associated a vessel, which is a collection of system operators
satisfying certain relations and vise versa. Such an invariance forces the
theory of vessels to resemble a constant (classical) 1D case and as a result
many notions are naturally redefined and most theorems are reproved in this
setting. The notion of transfer function and its connection to the
overdetermined 2D time invariant system (and the corresponding vessel) is one
of the topics of this work. It is well known that multiplicative structure of a
transfer function of a 1D system is closely connected to the decomposition of
the state space into invariant subspaces of the state operator and we
generalize this result to a wider class of functions. This class (denoted by
$\boldsymbol {\mathcal I}$) arises as a class of transfer functions, which
intertwine solutions of ODEs with spectral parameters. At the end we present
solution of factorization problems for finite dimensional case.


title: Complete Analytic Solutions of the Mie-type Potentials in N-Dimensions

abstract:
  The exact solutions of the N-dimensional Schrodinger equation with the
Mie-type potentials are obtained using the conventional Nikiforov-Uvarov
method.The expectation values r^{-1} and r^{-2}$ and the virial theorem are
also obtained in N-dimensions using the Hellmann-Feynman theorem.The ladder
operators are also construct for the Mie-type potentials in N-dimensions and
the matrix elements of some operators $r$ and r\frac{d}{dr} are analytically
obtained from the ladder operators.And the general results reduce to the
3-dimensional case when N=3.


title: Morphology and hardness ratio exploitation under limited statistics

abstract:
  Gamma-ray astronomy has produced for several years now sky maps for low
photon statistics, non-negligible background and comparatively poor angular
resolution. Quantifying the significance of spatial features remains difficult.
Besides, spectrum extraction requires regions with large statistics while maps
in energy bands allow only qualitative interpretation. The two main competing
mechanisms in the VHE domain are the Inverse-Compton emission from accelerated
electrons radiating through synchrotron in the X-ray domain and the
interactions between accelerated hadrons and the surrounding medium, leading to
the production and subsequent decay of Pi0 mesons. The spectrum of the VHE
emission from leptons is predicted to steepen with increasing distance from the
acceleration zone, owing to synchrotron losses (i.e. cooled population). It
would remain approximately constant for hadrons. Ideally, spectro-imaging
analysis would have the same spatial scale in the TeV and X-ray domains, to
distinguish the local emission mechanisms. More realistically, we investigate
here the possibility of improving upon the currently published HESS results by
using more sophisticated tools.


title: Distance dependence of entanglement generation via a bosonic heat bath

abstract:
  Within a generalized Caldeira-Leggett model we analyze the conditions under
which a bosonic heat bath can entangle two microscopic quantum systems at a
distance $r$. We find that the attainable entanglement is extremely
distance-sensitive. Significant entanglement can only be achieved if the
systems are within a {\em microscopic} distance that is of order of the cut-off
wavelength $\lambda$ of the system-bath interaction. At larger distances the
maximal entanglement is exponentially suppressed with a decay length of order
$\lambda$. We conclude that entanglement generation via a heat bath is not
suitable for entangling remote objects.


title: Partonic Pole Matrix Elements for Fragmentation

abstract:
  A model-independent analysis of collinear three-parton correlation functions
for fragmentation is performed. By investigating their support properties it is
shown, in particular, that the so-called partonic pole matrix elements vanish.
This sheds new light on the understanding of transverse single spin asymmetries
in various hard semi-inclusive reactions. Moreover, it gives additional strong
evidence for the universality of transverse-momentum-dependent fragmentation
functions.


title: Polarizable ions at interfaces

abstract:
  A non-perturbative theory is presented which allows to calculate the
solvation free energy of polarizable ions near a water-vapor and water-oil
interfaces. The theory predicts that larger halogen anions are adsorbed at the
interface, while the alkali metal cations are repelled from it. The density
profiles calculated theoretically are similar to those obtained using the
molecular dynamics simulations with polarizable force fields.


title: Frameworks, Symmetry and Rigidity

abstract:
  Symmetry equations are obtained for the rigidity matrix of a bar-joint
framework in R^d. These form the basis for a short proof of the Fowler-Guest
symmetry group generalisation of the Calladine-Maxwell counting rules. Similar
symmetry equations are obtained for the Jacobian of diverse framework systems,
including constrained point-line systems that appear in CAD, body-pin
frameworks, hybrid systems of distance constrained objects and infinite
bar-joint frameworks. This leads to generalised forms of the Fowler-Guest
character formula together with counting rules in terms of counts of
symmetry-fixed elements. Necessary conditions for isostaticity are obtained for
asymmetric frameworks, both when symmetries are present in subframeworks and
when symmetries occur in partition-derived frameworks.


title: The gluon propagator in Coulomb gauge from the lattice

abstract:
  We show that in the lattice Hamiltonian limit the static transverse
propagator $D(|\vec{p}|)\propto\int d p_0 D(|\vec{p}|,p_0)$ satisfies
multiplicative renormalizability. We give a procedure to calculate
$D(|\vec{p}|)$ on available lattices at finite temporal spacing. The result
agrees at all momenta with the Gribov formula $D(|\vec{p}|)\propto(|\vec{p}|^2+
M^4 |\vec{p}|^{-2})^{-{1/2}}$, with $M=0.88(1) {\rm GeV} \simeq 2
\sqrt{\sigma}$.


title: A non-abelian Stickelberger theorem

abstract:
  Let L/k be a finite Galois extension of number fields with Galois group G.
For every odd prime p satisfying certain mild technical hypotheses, we use
values of Artin L-functions to construct an element in the centre of the group
ring Z_(p)[G] that annihilates the p-part of the class group of L.


title: Foundations of SPARQL Query Optimization

abstract:
  The SPARQL query language is a recent W3C standard for processing RDF data, a
format that has been developed to encode information in a machine-readable way.
We investigate the foundations of SPARQL query optimization and (a) provide
novel complexity results for the SPARQL evaluation problem, showing that the
main source of complexity is operator OPTIONAL alone; (b) propose a
comprehensive set of algebraic query rewriting rules; (c) present a framework
for constraint-based SPARQL optimization based upon the well-known chase
procedure for Conjunctive Query minimization. In this line, we develop two
novel termination conditions for the chase. They subsume the strongest
conditions known so far and do not increase the complexity of the recognition
problem, thus making a larger class of both Conjunctive and SPARQL queries
amenable to constraint-based optimization. Our results are of immediate
practical interest and might empower any SPARQL query optimizer.


title:
Optimizing Nuclear Reaction Analysis (NRA) using Bayesian Experimental
  Design

abstract:
  Nuclear Reaction Analysis with ${}^{3}$He holds the promise to measure
Deuterium depth profiles up to large depths. However, the extraction of the
depth profile from the measured data is an ill-posed inversion problem. Here we
demonstrate how Bayesian Experimental Design can be used to optimize the number
of measurements as well as the measurement energies to maximize the information
gain. Comparison of the inversion properties of the optimized design with
standard settings reveals huge possible gains. Application of the posterior
sampling method allows to optimize the experimental settings interactively
during the measurement process.


title: Liquid metal experiments on the helical magnetorotational instability

abstract:
  The magnetorotational instability (MRI) plays an essential role in the
formation of stars and black holes. By destabilizing hydrodynamically stable
Keplerian flows, the MRI triggers turbulence and enables outward transport of
angular momentum in accretion discs. We present the results of a liquid metal
Taylor-Couette experiment under the influence of helical magnetic fields that
show typical features of MRI at Reynolds numbers of the order 1000 and Hartmann
numbers of the order 10. Particular focus is laid on an improved experiment in
which split end caps are used to minimize the Ekman pumping.


title: Entanglement of qubits via a nonlinear resonator

abstract:
  Coherent coupling of two qubits mediated by a nonlinear resonator is studied.
It is shown that the amount of entanglement accessible in the evolution depends
both on the strength of nonlinearity in the Hamiltonian of the resonator and on
the initial preparation of the system. The created entanglement survives in the
presence of decoherence.


title: On the Thermodynamic Geometry of Hot QCD

abstract:
  We study the nature of the covariant thermodynamic geometry arising from the
free energy of hot QCD. We systematically analyze the underlying equilibrium
thermodynamic configurations of the free energy of 2- and 3-flavor hot QCD with
or without including thermal fluctuations in the neighborhood of the QCD
transition temperature. We show that there exists a well-defined thermodynamic
geometric notion for QCD thermodynamics. The geometry thus obtained has no
singularity as an intrinsic Riemannian manifold. We further show that there is
a close connection of this geometric approach with the existing studies of
correlations and quark number susceptibilities in hot QCD.


title: Modified effective-range theory for low energy e-N2 scattering

abstract:
  We analyze the low-energy e-N2 collisions within the framework of the
Modified-Effective Range Theory (MERT) for the long-range potentials, developed
by O'Malley, Spruch and Rosenberg [Journal of Math. Phys. 2, 491 (1961)]. In
comparison to the traditional MERT we do not expand the total cross-section in
the series of the incident momentum \hbar k, but instead we apply the exact
analytical solutions of the Schroedinger equation for the long-range
polarization potential, as proposed in the original formulation of O'Malley et
al. This extends the applicability of MERT up to few eV regime, as we confirm
using some simplified model potential of the electron-molecule interaction. The
parameters of the effective-range expansion (i.e. the scattering length and the
effective range) are determined from experimental, integral elastic cross
sections in the 0.1 - 1.0 eV energy range by fitting procedure. Surprisingly,
our treatment predicts a shape resonance that appears slightly higher than
experimentally well known resonance in the total cross section. Agreement with
the experimentally observed shape-resonance can be improved by assuming the
position of the resonance in a given partial wave. Influence of the quadrupole
potential on resonances is also discussed: we show that it can be disregarded
for N2. In conclusion, the modified-effective range formalism treating the
long-range part of the potential in an exact way, reproduces well both the very
low-energy behavior of the integral cross section as well as the presence of
resonances in the few eV range.


title: Unitarity cutting rules for hard processes on nuclei

abstract:
  Heavy nuclei introduce a new scale into the pQCD description of hard
processes on nuclei, the saturation scale, and the familiar linear
k_\perp-factorization breaks down. It is replaced by a new concept, the
nonlinear k_\perp-factorization. Here we give a brief overview how topological
cross sections for hard processes on nuclei are obtained from nonlinear
k_\perp-factorization.


title:
Power Asymmetry in Cosmic Microwave Background Fluctuations from Full
  Sky to Sub-degree Scales: Is the Universe Isotropic?

abstract:
  We repeat and extend the analysis of Eriksen et al 2004 and Hansen et al 2004
testing the isotropy of the Cosmic Microwave Background (CMB) fluctuations. We
find that the hemispherical power asymmetry previously reported for the largest
scales l=2-40 extend to much smaller scales. In fact, for the full multipole
range l=2-600, significantly more power is found in the hemisphere centered at
(theta=107 deg., phi=226 deg.) in galactic co-latitude and longitude than in
the opposite hemisphere consistent with the previously detected direction of
asymmetry for l=2-40. We adopt a model selection test where the direction and
amplitude of asymmetry as well as the multipole range are free parameters. A
model with an asymmetric distribution of power for l=2-600 is found to be
preferred over the isotropic model at the 0.4% significance level taking into
account the additional parameters required to describe it. A similar direction
of asymmetry is found independently in all six subranges of 100 multipoles
between l=2-600 and none of our 9800 isotropic simulated maps show a similarly
consistent direction of asymmetry over such a large multipole range. No known
systematic effects or foregrounds are found to be able to explain the
asymmetry.


title:
The inhomogeneous equation of state and the speed of convergence to a
  small cosmological constant

abstract:
  The mechanism for the relaxation of the cosmological constant is studied and
elaborated. In the model used for the analysis of the relaxation mechanism the
universe contains two components: a cosmological constant of an arbitrary size
and sign and a component with an inhomogeneous equation of state. Owing to the
dynamics of the second component the universe asymptotically tends to a de
Sitter phase of expansion characterized by a small effective positive
cosmological constant. An analysis of the asymptotic expansion for a general
inhomogeneous equation of state of the second component is made. Several
concrete examples are presented and the stability and speed of convergence to
their fixed points are analyzed. It is found that the speed of convergence to a
fixed point is large whenever the absolute value of the cosmological constant
is large.


title: Domain structure of epitaxial Co films with perpendicular anisotropy

abstract:
  Epitaxial hcp Cobalt films with pronounced c-axis texture have been prepared
by pulsed lased deposition (PLD) either directly onto Al2O3 (0001) single
crystal substrates or with an intermediate Ruthenium buffer layer. The crystal
structure and epitaxial growth relation was studied by XRD, pole figure
measurements and reciprocal space mapping. Detailed VSM analysis shows that the
perpendicular anisotropy of these highly textured Co films reaches the
magnetocrystalline anisotropy of hcp-Co single crystal material. Films were
prepared with thickness t of 20 nm < t < 100 nm to study the crossover from
in-plane magnetization to out-of-plane magnetization in detail. The analysis of
the periodic domain pattern observed by magnetic force microscopy allows to
determine the critical minimum thickness below which the domains adopt a pure
in-plane orientation. Above the critical thickness the width of the stripe
domains is evaluated as a function of the film thickness and compared with
domain theory. Especially the discrepancies at smallest film thicknesses show
that the system is in an intermediate state between in-plane and out-of-plane
domains, which is not described by existing analytical domain models.


title: Vortex Core States in Superconducting Graphene

abstract:
  The distinctive features of the electronic structure of vortex states in
superconducting graphene are studied within the Bogolubov-de Gennes theory
applied to excitations near the Dirac point. We suggest a scenario describing
the subgap spectrum transformation which occurs with a change in the doping
level. For an arbitrary vorticity and doping level we investigate the problem
of existence of zero energy modes. The crossover to a Caroli - de Gennes -
Matricon type of spectrum is studied.


title: A Supersymmetric D4 Model for mu-tau Symmetry

abstract:
  We construct a supersymmeterized version of the model presented by Grimus and
Lavoura (GL) in [1] which predicts theta_{23} maximal and theta_{13}=0 in the
lepton sector. For this purpose, we extend the flavor group, which is D4 x
Z2^{(aux)} in the original model, to D4 x Z5. An additional difference is the
absence of right-handed neutrinos. Despite these changes the model is the same
as the GL model, since theta_{23} maximal and theta_{13}=0 arise through the
same mismatch of D4 subgroups, D2 in the charged lepton and Z2 in the neutrino
sector. In our setup D4 is solely broken by gauge singlets, the flavons. We
show that their vacuum structure, which leads to the prediction of theta_{13}
and theta_{23}, is a natural result of the scalar potential. We find that the
neutrino mass matrix only allows for inverted hierarchy, if we assume a certain
form of spontaneous CP violation. The quantity |m_{ee}|, measured in
neutrinoless double beta decay, is nearly equal to the lightest neutrino mass
m3. The Majorana phases phi1 and phi2 are restricted to a certain range for m3
< 0.06 eV. We discuss the next-to-leading order corrections which give rise to
shifts in the vacuum expectation values of the flavons. These induce deviations
from maximal atmospheric mixing and vanishing theta_{13}. It turns out that
these deviations are smaller for theta_{23} than for theta_{13}.


title:
Measurement of the Spin-forbidden Decay rate (3s3d)$^{1}$D$_{2}$ $\to$
  (3s3p)$^{3}$P$_{2,1}$ in $^{24}$Mg

abstract:
  We have measured the spin-forbidden decay rate from (3s3d)$^{1}$D$_{2}$ $\to$
(3s3p)$^{3}$P$_{2,1}$ in $^{24}$Mg atoms trapped in a magneto-optical trap. The
total decay rate, summing up both exit channels (3s3p)$^{3}$P$_{1}$ and
(3s3p)$^{3}$P$_{2}$, yields (196 $\pm$ 10) s$^{-1}$ in excellent agreement with
resent relativistic many-body calculations of [S.G. Porsev et al., Phys. Rev.
A. \textbf{64}, 012508 (2001)]. The characterization of this decay channel is
important as it may limit the performance of quantum optics experiments carried
out with this ladder system as well as two-photon cooling experiments currently
explored in several groups.


title:
3:1 magnetization plateau and suppression of ferroelectric polarization
  in an Ising chain multiferroic

abstract:
  Ferroelectric Ising chain magnet Ca$_3$Co$_{2-x}$Mn$_x$O$_6$ ($x\simeq$0.96)
was studied in magnetic fields up to 33 T. Magnetization and neutron scattering
measurements reveal successive metamagnetic transitions from the zero-field
$\uparrow \uparrow \downarrow \downarrow$ spin configuration to the $\uparrow
\uparrow \uparrow \downarrow$ state with a broad magnetization plateau, and
then to the $\uparrow \uparrow \uparrow \uparrow$ state. The absence of
hysteresis in these plateaus reveals an intriguing coupling between the
intra-chain state and the three-dimensional geometrically frustrated magnetic
system. Inversion symmetry, broken in the $\uparrow \uparrow \downarrow
\downarrow$ state, is restored in the $\uparrow \uparrow \uparrow \downarrow$
state, leading to the complete suppression of the electric polarization driven
by symmetric superexchange.


title: Multipomeron Cuts and Hard Processes on Nuclei

abstract:
  With nuclear targets comes a new scale into the pQCD description of hard
processes - the saturation scale. In the saturation regime, the familiar linear
k_\perp-factorization breaks down and must be replaced by a nonlinear
k_\perp-factorization, which accounts for absorptive and multiple scattering
corrections to the hard process. Predictions for partial cross sections
corresponding to a fixed number of cut Pomerons (the topological cross
sections) can be obtained in a surprisingly straightforward manner. We discuss
some applications to deep inelastic scattering.


title:
Rare K and B Decays in a Warped Extra Dimension with Custodial
  Protection

abstract:
  We present a complete study of rare K and B meson decays in a warped extra
dimensional model with a custodial protection of (both diagonal and
non-diagonal) Z d_L^i \bar d_L^j couplings, including K^+ -> pi^+ nu anti-nu,
K_L -> pi^0 nu anti-nu, K_L -> pi^0 l^+ l^-, K_L -> mu^+ mu^-, B_{s,d} -> mu^+
mu^-, B -> K nu anti-nu, B -> K^* nu anti-nu and B -> X_{s,d} nu anti-nu. In
this model in addition to Standard Model one loop contributions these processes
receive tree level contributions from the Z boson and the new heavy electroweak
gauge bosons. We analyse all these contributions that turn out to be dominated
by tree level Z boson exchanges governed by right-handed couplings to down-type
quarks. Imposing all existing constraints from Delta F=2 transitions analysed
by us recently and fitting all quark masses and CKM mixing parameters we find
that a number of branching ratios for rare K decays can differ significantly
from the SM predictions, while the corresponding effects in rare B decays are
modest, dominantly due to the custodial protection being more effective in B
decays than in K decays. In order to reduce the parameter dependence we study
correlations between various observables within the K system, within the B
system and in particular between K and B systems, and also between Delta F=2
and Delta F=1 observables. These correlations allow for a clear distinction
between this new physics scenario and models with minimal flavour violation or
the Littlest Higgs Model with T-parity, and could give an opportunity to future
experiments to confirm or rule out the model. We show how our results would
change if the custodial protection of Z d_L^i bar d^j_L couplings was absent.
In the case of rare B decays the modifications are spectacular.


title:
Search for Lepton Flavour Violating Decays $\tau \to \ell K^0_S$ with
  the BaBar Experiment

abstract:
  A search for the lepton flavour violating decays $\tau^- \to l^-
K^0_{\scriptscriptstyle S}$ ($l = e$ or $\mu$) has been performed using a data
sample corresponding to an integrated luminosity of 469 ${fb}^{-1}$, collected
with the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller
A\kern-0.2em R}} detector at the SLAC PEP-II $e^+e^-$ asymmetric energy
collider. No statistically significant signal has been observed in either
channel and the estimated upper limits on branching fractions are ${\cal
B}(\tau^- \to e^- K^0_{\scriptscriptstyle S}) < 3.3 \times 10^{-8}$ and ${\cal
B}(\tau^- \to \mu^- K^0_{\scriptscriptstyle S}) < 4.0 \times 10^{-8}$ at 90%
confidence level.


title:
Discovery of fossil magnetic fields in the intermediate-mass pre-main
  sequence stars

abstract:
  It is now well-known that the surface magnetic fields observed in cool,
lower-mass stars on the main sequence (MS) are generated by dynamos operating
in their convective envelopes. However, higher-mass stars (above 1.5 Msun) pass
their MS lives with a small convective core and a largely radiative envelope.
Remarkably, notwithstanding the absence of energetically-important envelope
convection, we observe very strong (from 300 G to 30 kG) and organised (mainly
dipolar) magnetic fields in a few percent of the A and B-type stars on the MS,
the origin of which is not well understood. In this poster we propose that
these magnetic fields could be of fossil origin, and we present very strong
observational results in favour of this proposal.


title:
Interfacial instability induced by lateral vapor pressure fluctuation in
  bounded thin liquid-vapor layers

abstract:
  We study an instability of thin liquid-vapor layers bounded by rigid parallel
walls from both below and above. In this system, the interfacial instability is
induced by lateral vapor pressure fluctuation, which is in turn attributed to
the effect of phase change: evaporation occurs at a hotter portion of the
interface and condensation at a colder one. The high vapor pressure pushes the
interface downward and the low one pulls it upward. A set of equations
describing the temporal evolution of the interface of the liquid-vapor layers
is derived. This model neglects the effect of mass loss or gain at the
interface and guarantees the mass conservation of the liquid layer. The result
of linear stability analysis of the model shows that the presence of the
pressure dependence of the local saturation temperature mitigates the growth of
long-wave disturbances. The thinner vapor layer enhances the vapor pressure
effect. We find the stability criterion, which suggests that only slight
temperature gradients are sufficient to overcome the gravitational effect for a
water/vapor system. The same holds for the Rayleigh-Taylor unstable case, with
a possibility that the vapor pressure effect may be weakened if the
accommodation coefficient is below a certain critical value.


title: Beyond Totally Reflexive Modules and Back

abstract:
  Starting from the notion of totally reflexive modules, we survey the theory
of Gorenstein homological dimensions for modules over commutative rings. The
account includes the theory's connections with relative homological algebra and
with studies of local ring homomorphisms. It ends close to the starting point:
with a characterization of Gorenstein rings in terms of total acyclicity of
complexes.


title:
A dissipative scheme to approach the boundary of two-qubit entangled
  mixed states

abstract:
  We discuss the generation of states close to the boundary-family of maximally
entangled mixed states as defined by the use of concurrence and linear entropy.
The coupling of two qubits to a dissipation-affected bosonic mode is able to
produce a bipartite state having, for all practical purposes, the entanglement
and purity properties of one of such boundary states. We thoroughly study the
effects that thermal and squeezed character of the bosonic mode have in such a
process and we discuss tolerance to qubit phase-damping mechanisms. The
non-demanding nature of the scheme makes it realizable in a matter-light based
physical set-up, which we address in some details.


title: High Energy Neutrino Telescopes

abstract:
  This paper presents a review of the history, motivation and current status of
high energy neutrino telescopes. Many years after these detectors were first
conceived, the operation of kilometer-cubed scale detectors is finally on the
horizon at both the South Pole and in the Mediterranean Sea. These new
detectors will perhaps provide us the first view of high energy astrophysical
objects with a new messenger particle and provide us with our first real
glimpse of the distant universe at energies above those accessible by gamma-ray
instruments. Some of the topics that can be addressed by these new instruments
include the origin of cosmic rays, the nature of dark matter, and the
mechanisms at work in high energy astrophysical objects such as gamma-ray
bursts, active galactic nuclei, pulsar wind nebula and supernova remnants.


title:
Four-dimensional couplings among BF and massless Rarita-Schwinger
  theories: a BRST cohomological approach

abstract:
  The local and manifestly covariant Lagrangian interactions in four spacetime
dimensions that can be added to a free model that describes a massless
Rarita-Schwinger theory and an Abelian BF theory are constructed by means of
deforming the solution to the master equation on behalf of specific
cohomological techniques.


title: A Scaling Hypothesis for Modulated Systems

abstract:
  We propose a scaling hypothesis for pattern-forming systems in which
modulation of the order parameter results from the competition between a
short-ranged interaction and a long-ranged interaction decaying with some power
$\alpha$ of the inverse distance. With L being a spatial length characterizing
the modulated phase, all thermodynamic quantities are predicted to scale like
some power of L. The scaling dimensions with respect to L only depend on the
dimensionality of the system d and the exponent \alpha. Scaling predictions are
in agreement with experiments on ultra-thin ferromagnetic films and
computational results. Finally, our scaling hypothesis implies that, for some
range of values \alpha>d, Inverse-Symmetry-Breaking transitions may appear
systematically in the considered class of frustrated systems.


title: Competing many-body interactions in systems of trapped ions

abstract:
  We propose and theoretically analyse an experimental configuration in which
lasers induce 3-spin interactions between trapped ions.By properly choosing the
intensities and frequencies of the lasers, 3-spin couplings may be dominant or
comparable to 2-spin terms and magnetic fields. In this way, trapped ions can
be used to study exotic quantum phases which do not have a counterpart in
nature. We study the conditions for the validity of the effective 3-spin
Hamiltonian, and predict qualitatively the quantum phase diagram of the system.


title: Parabolic systems with coupled boundary conditions

abstract:
  We consider elliptic operators with operator-valued coefficients and discuss
the associated parabolic problems. The unknowns are functions with values in a
Hilbert space $W$. The system is equipped with a general class of coupled
boundary conditions of the form $f_{|\partial\Omega}\in \mathcal Y$ and
$\frac{\partial f}{\partial \nu}\in {\mathcal Y}^\perp$, where $\mathcal Y$ is
a closed subspace of $L^2(\partial\Omega;W)$. We discuss well-posedness and
further qualitative properties, systematically reducing features of the
parabolic system to operator-theoretical properties of the orthogonal
projection onto $\mathcal Y$.


title:
Moving towards nano-TCAD through multimillion atom quantum dot
  simulations matching experimental data

abstract:
  Low-loss optical communication requires light sources at 1.5um wavelengths.
Experiments showed without much theoretical guidance that InAs/GaAs quantum
dots (QDs) may be tuned to such wavelengths by adjusting the In fraction in an
InxGa1-xAs strain-reducing capping layer (SRCL). In this work systematic
multimillion atom electronic structure calculations qualitatively and
quantitatively explain for the first time available experimental data. The NEMO
3-D simulations treat strain in a 15 million atom system and electronic
structure in a subset of ~9 million atoms using the experimentally given
nominal geometries and without any further parameter adjustments the
simulations match the nonlinear behavior of experimental data very closely.
With the match to experimental data and the availability of internal model
quantities significant insight can be gained through mapping to reduced order
models and their relative importance. We can also demonstrate that starting
from simple models has in the past led to the wrong conclusions. The critical
new insight presented here is that the QD changes its shape. The quantitative
simulation agreement with experiment without any material or geometry parameter
adjustment in a general atomistic tool leads us to believe that the era of nano
Technology Computer Aided Design (nano-TCAD) is approaching. NEMO 3-D will be
released on nanoHUB.org where the community can duplicate and expand on the
results presented here through interactive simulations.


title:
MSSM Higgs Boson Production via Gluon Fusion: The Large Gluino Mass
  Limit

abstract:
  Scalar MSSM Higgs boson production via gluon fusion gg -> h,H is mediated by
heavy quark and squark loops. The higher order QCD corrections to these
processes turn out to be large. The full supersymmetric QCD corrections have
been calculated recently. In the limit of large SUSY masses a conceptual
problem appears, i.e. the proper treatment of the large gluino mass limit. In
this work we will describe the consistent decoupling of heavy gluino effects
and derive the effective Lagrangian for decoupled gluinos.


title: Sur les automorphismes reguliers de C^k

abstract:
  We show the uniqueness for the measure of maximal entropy for regular
automorphisms of C^k.


title: Multiple orthogonal polynomials, string equations and the large-n limit

abstract:
  The Riemann-Hilbert problems for multiple orthogonal polynomials of types I
and II are used to derive string equations associated to pairs of Lax-Orlov
operators. A method for determining the quasiclassical limit of string
equations in the phase space of the Whitham hierarchy of dispersionless
integrable systems is provided. Applications to the analysis of the large-n
limit of multiple orthogonal polynomials and their associated random matrix
ensembles and models of non-intersecting Brownian motions are given.


title: Entanglement in open quantum dynamics

abstract:
  In the framework of the theory of open systems based on completely positive
quantum dynamical semigroups, we give a description of the continuous-variable
entanglement for a system consisting of two independent harmonic oscillators
interacting with a general environment. Using Peres-Simon necessary and
sufficient criterion for separability of two-mode Gaussian states, we describe
the generation and evolution of entanglement in terms of the covariance matrix
for an arbitrary Gaussian input state. For some values of diffusion and
dissipation coefficients describing the environment, the state keeps for all
times its initial type: separable or entangled. In other cases, entanglement
generation or entanglement collapse (entanglement sudden death) take place or
even a periodic collapse and revival of entanglement. We show that for certain
classes of environments the initial state evolves asymptotically to an
entangled equilibrium bipartite state, while for other values of the
coefficients describing the environment, the asymptotic state is separable. We
calculate also the logarithmic negativity characterizing the degree of
entanglement of the asymptotic state.


title:
Quantum ground-state cooling and tripartite entanglement with three-mode
  optoacoustic interactions

abstract:
  We present a quantum analysis of three-mode optoacoustic parametric
interactions in an optical cavity, in which two orthogonal transverse
optical-cavity modes are coupled to one acoustic mode through radiation
pressure. Due to the optimal frequency matching -- the frequency separation of
two cavity modes is equal to the acoustic-mode frequency -- the carrier and
sideband fields simultaneously resonate and coherently build up. This mechanism
significantly enhances the optoacoustic couplings in the quantum regime. It
allows exploration of quantum behavior of optoacoustic interactions in
small-scale table-top experiments. We show explicitly that given an
experimentally achievable parameter, three-mode scheme can realize quantum
ground-state cooling of milligram scale mechanical oscillators and create
robust stationary tripartite optoacoustic quantum entanglements.


title: Effective Field Theories and Matching for Codimension-2 Branes

abstract:
  It is generic for the bulk fields sourced by branes having codimension two
and higher to diverge at the brane position, much as does the Coulomb potential
at the position of its source charge. This complicates finding the relation
between brane properties and the bulk geometries they source. (These
complications do not arise for codimension-1 sources, such as in RS geometries,
because of the special properties unique to codimension one.) Understanding
these relations is a prerequisite for phenomenological applications involving
higher-codimension branes. Using codimension-2 branes in extra-dimensional
scalar-tensor theories as an example, we identify the classical matching
conditions that relate the near-brane asymptotic behaviour of bulk fields to
the low-energy effective actions describing how space-filling codimension-2
branes interact with the surrounding extra-dimensional bulk. We do so by
carefully regulating the near-brane divergences, and show how these may be
renormalized in a general way. Among the interesting consequences is a
constraint relating the on-brane curvature to its action, that is the
codimension-2 generalization of the well-known modification of the Friedmann
equation for codimension-1 branes. We argue that its interpretation within an
effective field theory framework in this case is as a relation $4\pi U \simeq
\kappa^2 (T')^2$ between the codimension-2 brane tension, T, and its
contribution to the low-energy on-brane effective potential, U. This relation
implies that any dynamics that minimizes a brane contribution to the on-brane
curvature automatically also minimizes its couplings to the extra-dimensional
scalar.


title:
Magnetic order in a spin-half interpolating square-triangle Heisenberg
  antiferromagnet

abstract:
  Using the coupled cluster method we study the zero-temperature phase diagram
of a spin-half Heisenberg antiferromagnet (HAF), the so-called
$J_{1}$--$J_{2}'$ model, defined on an anisotropic 2D lattice. With respect to
an underlying square-lattice geometry the model contains antiferromagnetic
($J_{1} > 0$) bonds between nearest neighbors and competing ($J_{2}'>0$) bonds
between next-nearest neighbors across only one of the diagonals of each square
plaquette, the same diagonal in every square. Considered on an equivalent
triangular-lattice geometry the model may be regarded as having two sorts of
nearest-neighbor bonds, with $J_{2}' \equiv \kappa J_{1}$ bonds along parallel
chains and $J_{1}$ bonds providing an interchain coupling. Hence, the model
interpolates between a spin-half HAF on the square lattice at one extreme
($\kappa = 0$) and a set of decoupled spin-half chains at the other ($\kappa
\to \infty$), with the spin-half HAF on the triangular lattice in between at
$\kappa = 1$. We find strong evidence that quantum fluctuations favor a
first-order transition from quasiclassical N\'{e}el order to a quantum helical
state at a first critical point at $\kappa_{c_{1}} = 0.80 \pm 0.01$, by
contrast with the corresponding second-order transition between the equivalent
classical states at $\kappa_{{\rm cl}} = 0.5$. We also find strong evidence for
a second critical point at $\kappa_{c_{2}} = 1.8 \pm 0.4$ where another
first-order transition occurs, this time from the quantum helical phase to a
collinear stripe-ordered phase. This latter result provides quantitative
verification of a recent qualitative prediction of Starykh and Balents [Phys.\
Rev. Lett. {\bf 98}, 077205 (2007)] for the $J_{1}$--$J_{2}'$ model that did
not, however, evaluate the corresponding critical point.


title:
Two-scale semi-lagrangian simulation of a charged particle beam in a
  periodic focusing channel

abstract:
  This paper is devoted to numerical simulation of a charged particle beam
submitted to a strong oscillating electric field. For that, we consider a
two-scale numerical approach as follows: we first recall the two-scale model
which is obtained by using two-scale convergence techniques; then, we
numerically solve this limit model by using a backward semi-lagrangian method
and we propose a new mesh of the phase space which allows us to simplify the
solution of the Poisson's equation. Finally, we present some numerical results
which have been obtained by the new method, and we validate its efficiency
through long time simulations.


title:
The solar wind charge-transfer X-ray emission in the 1/4 keV energy
  range: inferences on Local Bubble hot gas at low Z

abstract:
  We present calculations of the heliospheric SWCX emission spectra and their
contributions in the ROSAT 1/4 keV band. We compare our results with the soft
X-ray diffuse background (SXRB) emission detected in front of 378 identified
shadowing regions during the ROSAT All-Sky Survey (Snowden et al. 2000). This
foreground component is principally attributed to the hot gas of the so-called
Local Bubble (LB), an irregularly shaped cavity of ~50-150 pc around the Sun,
which is supposed to contain ~10^6 K plasma. Our results suggest that the SWCX
emission from the heliosphere is bright enough to account for most of the
foreground emission towards the majority of low galactic latitude directions,
where the LB is the least extended. In a large part of directions with galactic
latitude above 30deg the heliospheric SWCX intensity is significantly smaller
than the measured one. However, the SWCX R2/R1 band ratio differs slightly from
the data in the galactic center direction, and more significantly in the
galactic anti-centre direction where the observed ratio is the smallest.
Assuming that both SWCX and hot gas emission are present and their relative
contributions vary with direction, we tested a series of thermal plasma spectra
for temperatures ranging from 10^5 to 10^6.5 K and searched for a combination
of SWCX spectra and thermal emission matching the observed intensities and band
ratios, while simultaneously being compatible with O VI emission measurements.
In the frame of collisional equilibrium models and for solar abundances, the
range we derive for hot gas temperature and emission measure cannot reproduce
the Wisconsin C/B band ratio. We emphasize the need for additional atomic data,
describing consistently EUV and X-ray photon spectra of the charge-exchange
emission of heavier solar wind ions.


title:
Efficient Parametrization of the Vertex Function, $\Omega$-Scheme, and
  the (t,t')-Hubbard Model at Van Hove Filling

abstract:
  We propose a new parametrization of the four-point vertex function in the
one-loop one-particle irreducible renormalization group (RG) scheme for
fermions. It is based on a decomposition of the effective two-fermion
interaction into fermion bilinears that interact via exchange bosons. The
numerical computation of the RG flow of the boson propagators reproduces the
leading weak coupling instabilities of the two-dimensional Hubbard model at Van
Hove filling, as they were previously obtained by a temperature RG flow.
Instead of regularizing with temperature, we here use a soft frequency
$\Omega$-regularization that likewise does not artificially suppress
ferromagnetism. Besides being more efficient than previous N-patch schemes,
this parametrization also reduces the ambiguities in introducing boson fields.


title:
Simple condensation of composite bosons in a number conserving approach
  to many fermion systems

abstract:
  We recently derived the Hamiltonian of fermionic composites by an exact
procedure of bosonization. In the present paper expand this Hamiltonian in the
inverse of the number of fermionic states in the composite wave function and
give the necessary and sufficient conditions for the validity of such an
expansion. We compare the results to the Random phase Approximation and the BCS
theory and perform an illustrative application of the method.


title: Franck-Condon blockade in suspended carbon nanotube quantum dots

abstract:
  Understanding the influence of vibrational motion of the atoms on electronic
transitions in molecules constitutes a cornerstone of quantum physics, as
epitomized by the Franck-Condon principle of spectroscopy. Recent advances in
building molecular-electronics devices and nanoelectromechanical systems open a
new arena for studying the interaction between mechanical and electronic
degrees of freedom in transport at the single-molecule level. The tunneling of
electrons through molecules or suspended quantum dots has been shown to excite
vibrational modes, or vibrons. Beyond this effect, theory predicts that strong
electron-vibron coupling dramatically suppresses the current flow at low
biases, a collective behaviour known as Franck-Condon blockade. Here we show
measurements on quantum dots formed in suspended single-wall carbon nanotubes
revealing a remarkably large electron-vibron coupling and, due to the high
quality and unprecedented tunability of our samples, admit a quantitative
analysis of vibron-mediated electronic transport in the regime of strong
electron-vibron coupling. This allows us to unambiguously demonstrate the
Franck-Condon blockade in a suspended nanostructure. The large observed
electron-vibron coupling could ultimately be a key ingredient for the detection
of quantized mechanical motion. It also emphasizes the unique potential for
nanoelectromechanical device applications based on suspended graphene sheets
and carbon nanotubes.


title: Long-term chromospheric activity of non-eclipsing RS CVn-type stars

abstract:
  Context. The IUE database provides a large number of UV high and
low-resolution spectra of RS CVn-type stars from 1978 to 1996. In particular,
many of these stars were monitored continuously during several seasons by IUE.
Aims. Our main purpose is to study the short and long-term chromospheric
activity of the RS CVn systems most observed by IUE: HD 22468 (V711 Tau, HR
1099, K1IV+G5V), HD 21242 (UX Ari, K0IV+G5V) and HD 224085 (II Peg, K2IV).
Methods. We first obtain the Mount Wilson index S from the IUE high and
low-resolution spectra. Secondly, we analyse with the Lomb-Scargle periodogram
the mean annual index S and the amplitude of its rotational modulation.
Results. For HD 22468 (V711 Tau, HR 1099), we found a possible chromospheric
cycle with a period of 18 years and a shorter cycle with a period of 3 years,
which could be associated to a chromospheric "flip-flop" cycle. The data of HD
224085 (II Peg) also suggest a chromospheric cycle of 21 years and a flip-flop
cycle of 9 years. Finally, we obtained a possible chromospheric cycle of 7
years for HD 21242 (UX Ari).


title: Evidence for a hard equation of state in the cores of neutron stars

abstract:
  The equation of state for matter with energy density above 2 x10^14 g/cm^3 is
parametrized by P = kN^Gamma, where N is the number density, Gamma is the
adiabatic index, and k a constant. Using this scheme to generate thousands of
models, together with data on neutron star masses, it is found, for a core
region with a constant adiabatic index, that the central density must satisfy
10^15 gm/cm^3 < rho_c < 10^16 gm/cm^3, with Gamma > 2.2. Further preliminary
results indicate, based on the observed neutrino flux from supernova 1987a,
that this number must be considerably higher, on the order of 3.5. These
results provide evidence for a hard equation of state in the cores of neutron
stars.


title: Heavy Quark Interactions and Quarkonium Binding

abstract:
  We consider heavy quark interactions in quenched and unquenched lattice QCD.
In a region just above the deconfinement point, non-Abelian gluon polarization
leads to a strong increase in the binding. Comparing quark-antiquark and
quark-quark interaction, the dependence of the binding on the separation
distance $r$ is found to be the same for the colorless singlet $Q\bar Q$ and
the colored anti-triplet $QQ$ state. In a potential model description of
in-medium $J/\Psi$ behavior, this enhancement of the binding leads to a
survival up to temperatures of 1.5 $T_c$ or higher; it could also result in
$J/\Psi$ flow.


title: Model-independent analysis of Tau -> lll' decays

abstract:
  Many models for physics beyond the Standard Model predict lepton-flavour
violating decays of charged leptons at a level which may become observable very
soon. We investigate the decays of a Tau-lepton into three charged leptons (Tau
-> lll', l(') = e,\mu in a generic way. Using effective-field-theory methods,
the relevant operators are classified according to their chirality structure.
For each case, we work out the Dalitz plots for the decay distributions,
including interference terms which arise from four-lepton operators and
radiatively induced processes. We discuss phenomenological implications, in
particular the potential to distinguish different new physics models.


title:
A Comparison of Six Photometric Redshift Methods Applied to 1.5 Million
  Luminous Red Galaxies

abstract:
  We present an updated version of MegaZ-LRG (Collister et al.,(2007)) with
photometric redshifts derived with the neural network method, ANNz as well as
five other publicly available photo-z codes (HyperZ, SDSS, Le PHARE, BPZ and
ZEBRA) for ~1.5 million Luminous Red Galaxies (LRGs) in SDSS DR6. This allows
us to identify how reliable codes are relative to each other if used as
described in their public release. We compare and contrast the relative merits
of each code using ~13000 spectroscopic redshifts from the 2SLAQ sample. We
find that the performance of each code depends on the figure of merit used to
assess it. As expected, the availability of a complete training set means that
the training method performs best in the intermediate redshift bins where there
are plenty of training objects. Codes such as Le PHARE, which use new observed
templates perform best in the lower redshift bins. All codes produce reasonable
photometric redshifts, the 1-sigma scatters ranging from 0.057 to 0.097 if
averaged over the entire redshift range. We also perform tests to check whether
a training set from a small region of the sky such as 2SLAQ produces biases if
used to train over a larger area of the sky. We conclude that this is not
likely to be a problem for future wide-field surveys. The complete photometric
redshift catalogue including redshift estimates and errors on these from all
six methods can be found at www.star.ucl.ac.uk/~mbanerji/MegaZLRGDR6/megaz.html


title: Distinguishability measures between ensembles of quantum states

abstract:
  A quantum ensemble $\{(p_x, \rho_x)\}$ is a set of quantum states each
occurring randomly with a given probability. Quantum ensembles are necessary to
describe situations with incomplete a priori information, such as the output of
a stochastic quantum channel (generalized measurement), and play a central role
in quantum communication. In this paper, we propose measures of distance and
fidelity between two quantum ensembles. We consider two approaches: the first
one is based on the ability to mimic one ensemble given the other one as a
resource and is closely related to the Monge-Kantorovich optimal transportation
problem, while the second one uses the idea of extended-Hilbert-space (EHS)
representations which introduce auxiliary pointer (or flag) states. Both types
of measures enjoy a number of desirable properties. The Kantorovich measures,
albeit monotonic under deterministic quantum operations, are not monotonic
under generalized measurements. In contrast, the EHS measures are. We present
operational interpretations for both types of measures. We also show that the
EHS fidelity between ensembles provides a novel interpretation of the fidelity
between mixed states--the latter is equal to the maximum of the fidelity
between all pure-state ensembles whose averages are equal to the mixed states
being compared. We finally use the new measures to define distance and fidelity
for stochastic quantum channels and positive operator-valued measures (POVMs).
These quantities may be useful in the context of tomography of stochastic
quantum channels and quantum detectors.


title:
Regarding the Potential Impact of Double Star Observations on
  Conceptions of the Universe of Stars in the Early 17th Century

abstract:
  Galileo Galilei believed that stars were distant suns whose sizes, measured
via his telescope, were a direct indication of distance -- fainter stars
(appearing smaller in the telescope) were farther away than brighter ones.
Galileo argued in his Dialogue that telescopic observation of a chance
alignment of a faint (distant) and bright (closer) star would reveal annual
parallax, if such double stars could be found. This would provide support both
for Galileo's ideas concerning the nature of stars and for the motion of the
Earth. However, Galileo actually made observations of such double stars, well
before publication of the Dialogue. We show that the results of these
observations, and the likely results of observations of any double star that
was a viable subject for Galileo's telescope, would undermine Galileo's ideas,
not support them. We argue that such observations would lead either to the more
correct conclusion that stars were sun-like bodies of varying sizes which could
be physically grouped, or to the less correct conclusion that stars are not
sun-like bodies, and even to the idea that the Earth did not move. Lastly, we
contrast these conclusions to those reached through applying Galileo's ideas to
observations of visible stars as a whole.


title:
Up-to N$^3$LO heavy-baryon chiral perturbation theory calculation for
  the M1 properties of three-nucleon systems

abstract:
  M1 properties, comprising magnetic moments and radiative capture of thermal
neutron observables, are studied in two- and three-nucleon systems. We utilize
meson exchange current derived up to N$^3$LO using heavy baryon chiral
perturbation theory a la Weinberg. Calculations have been performed for several
qualitatively different realistic nuclear Hamiltonians, which permits us to
analyze model dependence of our results. Our results are found to be strongly
correlated with the effective range parameters such as binding energies and the
scattering lengths. Taking into account such correlation, the results are in
good agreement with the experimental data with small model-dependence.


title:
Interpolation between static local field corrections and the Drude model
  by a generalized Mermin approach

abstract:
  In non-ideal plasmas, the dielectric function has to be treated beyond the
random phase approximation. Correlations and well as collisions have to be
included. These corrections are known as (dynamical) local field corrections.
With the help of the Zubarev approach to linear response theory, a relaxation
time approximation is proposed leading to an interpolation scheme between
static local field corrections and the Drude model in the long wave length
limit. The approach generalizes the Mermin approximation for the dielectric
function and allows for the inclusion of a dynamical collision frequency.
Exploratory calculations for a classical two-component plasma at intermediate
coupling are presented.


title: Bootstrapping Inductive and Coinductive Types in HasCASL

abstract:
  We discuss the treatment of initial datatypes and final process types in the
wide-spectrum language HasCASL. In particular, we present specifications that
illustrate how datatypes and process types arise as bootstrapped concepts using
HasCASL's type class mechanism, and we describe constructions of types of
finite and infinite trees that establish the conservativity of datatype and
process type declarations adhering to certain reasonable formats. The latter
amounts to modifying known constructions from HOL to avoid unique choice; in
categorical terminology, this means that we establish that quasitoposes with an
internal natural numbers object support initial algebras and final coalgebras
for a range of polynomial functors, thereby partially generalising
corresponding results from topos theory. Moreover, we present similar
constructions in categories of internal complete partial orders in
quasitoposes.


title:
Neutrino Mass Seesaw at the Weak Scale, the Baryon Asymmetry, and the
  LHC

abstract:
  We consider theories where the Standard Model (SM) neutrinos acquire masses
through the seesaw mechanism at the weak scale. We show that in such a
scenario, the requirement that any pre-existing baryon asymmetry, regardless of
its origin, not be washed out leads to correlations between the pattern of SM
neutrino masses and the spectrum of new particles at the weak scale, leading to
definite predictions for the LHC. For type I seesaw models with a TeV scale Z'
coupled to SM neutrinos, we find that for a normal neutrino mass hierarchy, at
least one of the right-handed neutrinos must be `electrophobic', decaying with
a strong preference into final states with muons and tauons rather than
electrons. For inverted or quasi-degenerate mass patterns, on the other hand,
we find upper bounds on the mass of at least one right-handed neutrino. In
particular, for an inverted mass hierarchy, this bound is 1 TeV, while the
corresponding upper limit in the quasi-degenerate case is 300 GeV. Similar
results hold in type III seesaw models, albeit with somewhat more stringent
bounds. For the Type II seesaw case with a weak scale SU(2) triplet Higgs, we
again find that an interesting range of Higgs triplet masses is disallowed by
these considerations.


title: Updated Pre-Main Sequence tracks at low metallicities for 0.1< M/Mo<1.5

abstract:
  Young populations at Z<Zo are being examined to understand the role of
metallicity in the first phases of stellar evolution. For the analysis it is
necessary to assign mass and age to Pre--Main Sequence (PMS) stars. While it is
well known that the mass and age determination of PMS stars is strongly
affected by the convection treatment, extending any calibration to
metallicities different from solar one is very artificial, in the absence of
any calibrators for the convective parameters. For solar abundance, Mixing
Lenght Theory models have been calibrated by using the results of 2D
radiative-hydrodynamical models (MLTa2D), that result to be very similar to
those computed with non-grey ATLAS9 atmosphere boundary condition and full
spectrum of turbolence (FST) convection model both in the atmosphere and in the
interior (NEMO--FST models). While MLTa2D models are not available for lower
metallicities, we extend to lower Z the NEMO--FST models, in the educated guess
that in such a way we are simulating also at smaller Z the results of MLTa2D.
We present PMS models for low mass stars from 0.1 to 1.5 Mo for metallicities
[Fe/H]= -0.5, -1.0 and -2.0. The calculations include the most recent interior
physics and the latest generation of non-grey atmosphere models. These
evolutionary tracks and isochrones are available in electronic form at a WEB
site http://www.mporzio.astro.it/%7Etsa/


title: QCD Matter Thermalization at RHIC and LHC

abstract:
  Employing the perturbative QCD inspired parton cascade, we investigate
kinetic and chemical equilibration of the partonic matter created in central
heavy ion collisions at RHIC and LHC energies. Two types of initial conditions
are chosen. One is generated by the model of wounded nucleons using the PYTHIA
event generator and Glauber geometry. Another is considered as a color glass
condensate. We show that kinetic equilibration is almost independent on the
chosen initial conditions, whereas there is a sensitive dependence for chemical
equilibration. The time scale of thermalization lies between 1 and 1.5 fm/c.
The final parton transverse energy obtained from BAMPS calculations is compared
with the RHIC data and is estimated for the LHC energy.


title:
Epidemics with Multistrain Interactions: The Interplay Between Cross
  Immunity and Antibody-Dependent Enhancement

abstract:
  This paper examines the interplay of the effect of cross immunity and
antibody-dependent enhancement (ADE) in mutistrain diseases. Motivated by
dengue fever, we study a model for the spreading of epidemics in a population
with multistrain interactions mediated by both partial temporary cross immunity
and ADE. Although ADE models have previously been observed to cause chaotic
outbreaks, we show analytically that weak cross immunity has a stabilizing
effect on the system. That is, the onset of disease fluctuations requires a
larger value of ADE with small cross immunity than without. However, strong
cross immunity is shown numerically to cause oscillations and chaotic outbreaks
even for low values of ADE.


title: Examples of stable embedded minimal spheres without area bounds

abstract:
  The author proves that there is an open non empty set of metrics on any
3-manifold such that there exists a family of stably embedded minimal 2-spheres
whose area is unbounded. This generalizes the work of T. Colding and W.
Minicozzi who have shown an analogous result for the torus and B. Dean who
showed the positive genus case.


title: Coulomb gauge ghost propagator and the Coulomb potential

abstract:
  The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge
on the lattice, using an improved gauge fixing scheme which includes the
residual symmetry. This setting has been shown to be essential in order to
explain the scaling violations in the instantaneous gluon propagator. We find
that both the ghost propagator and the Coulomb potential are insensitive to the
Gribov problem or the details of the residual gauge fixing, even if the Coulomb
potential is evaluated from the A0--propagator instead of the Coulomb kernel.
In particular, no signs of scaling violations could be found in either
quantity, at least to well below the numerical accuracy where these violations
were visible for the gluon propagator. The Coulomb potential from the
A0-propagator is shown to be in qualitative agreement with the (formally
equivalent) expression evaluated from the Coulomb kernel.


title:
Scalar resonances in a unitary $\pi-\pi$ $S$-wave model for $D^+ \to
  \pi^+ \pi^- \pi^+$

abstract:
  We propose a model for $D^+ \to \pi^+ \pi^- \pi^+$ decays following
experimental results which indicate that the two-pion interaction in the
$S$-wave is dominated by the scalar resonances $f_0(600)/\sigma$ and
$f_0(980)$. The weak decay amplitude for $D^+\to R \pi^+$, where $R$ is a
resonance that subsequently decays into $\pi^+\pi^-$, is constructed in a
factorization approach. In the $S$-wave, we implement the strong decay $R\to
\pi^-\pi^+$ by means of a scalar form factor. This provides a unitary
description of the pion-pion interaction in the entire kinematically allowed
mass range $m_{\pi\pi}^2$ from threshold to about 3 GeV$^2$. In order to
reproduce the experimental Dalitz plot for $\Dppp$, we include contributions
beyond the $S$-wave. For the $P$-wave, dominated by the $\rho(770)^0$, we use a
Breit-Wigner description. Higher waves are accounted for by using the usual
isobar prescription for the $f_2(1270)$ and $\rho(1450)^0$. The major
achievement is a good reproduction of the experimental $m_{\pi\pi}^2$
distribution, and of the partial as well as the total $\Dppp$ branching ratios.
Our values are generally smaller than the experimental ones. We discuss this
shortcoming and, as a byproduct, we predict a value for the poorly known $D\to
\sigma$ transition form factor at $q^2=m_\pi^2$.


title: Two-dimensional weakly interacting Bose gas: equation of state

abstract:
  The equation of state of a weakly interacting two-dimensional Bose gas is
studied at zero temperature by means of quantum Monte Carlo methods. Going down
to as low densities as na^2 ~ 10^{-100} permits us for the first time to obtain
agreement on beyond mean-field level between predictions of perturbative
methods and direct many-body numerical simulation, thus providing an answer to
the fundamental question of the equation of state of a two-dimensional dilute
Bose gas in the universal regime (i.e. entirely described by the gas parameter
na^2). We also show that the measure of the frequency of a breathing collective
oscillation in a trap at very low densities can be used to test the universal
equation of state of a two-dimensional Bose gas.


title: Investigations of hadron structure on the lattice

abstract:
  Lattice simulations of hadronic structure are now reaching a level where they
are able to not only complement, but also provide guidance to current and
forthcoming experimental programmes at, e.g. Jefferson Lab, COMPASS/CERN and
FAIR/GSI. In this talk I review the progress that has been made in this
exciting area in the past year and discuss the advances that we can expect to
see in the coming year.Topics to be covered include form factors (including
transition form factors), moments of ordinary parton and generalised parton
distribution functions, moments of distribution amplitudes, and magnetic and
electric polarisabilities. I will also highlight the progress being made in
determining disconnected contributions to hadronic properties. Of particular
interest here is the size of the contribution to various nucleonic properties
coming from strange quarks.


title:
Systematization of Basic Divergent Integrals in Perturbation Theory and
  Renormalization Group Functions

abstract:
  We show that to n loop order the divergent content of a Feynman amplitude is
spanned by a set of basic (logarithmically divergent) integrals which need not
be evaluated. Only the coefficients of the basic divergent integrals are
necessary to determine renormalization group functions. Relations between these
coefficients of different loop orders are derived.


title: Dynamics of a colloid-stabilized cream

abstract:
  We use x-ray photon correlation spectroscopy to investigate the dynamics of a
high volume fraction emulsion creaming under gravity. The dodecane-in-water
emulsion has interfaces stabilized solely by colloidal particles (silica). The
samples were observed soon after mixing: as the emulsion becomes compact we
discern two regimes of ageing with a cross-over between them. The young
emulsion has faster dynamics associated with creaming in a crowded environment
accompanied by local rearrangements. The dynamics slow down for the older
emulsion although our studies show that motion is associated with large
intermittent events. The relaxation rate, as seen from the intensity
autocorrelation function, depends linearly on the wave vector at all times;
however, the exponent associated with the line shape changes from 1.5 for young
samples to less than 1 as the emulsion ages. The combination of ballisticlike
dynamics, an exponent that drops below 1 and large intermittent fluctuations
has not been reported before.


title: The critical Z-invariant Ising model via dimers: the periodic case

abstract:
  We study a large class of critical two-dimensional Ising models namely
critical Z-invariant Ising models on periodic graphs, example of which are the
classical square, triangular and honeycomb lattice at the critical temperature.
Fisher introduced a correspondence between the Ising model and the dimer model
on a decorated graph, thus setting dimer techniques as a powerful tool for
understanding the Ising model. In this paper, we give a full description of the
dimer model corresponding to the critical Z-invariant Ising model. We prove
that the dimer characteristic polynomial is equal (up to a constant) to the
critical Laplacian characteristic polynomial, and defines a Harnack curve of
genus 0. We prove an explicit expression for the free energy, and for the Gibbs
measure obtained as weak limit of Boltzmann measures.


title:
Large grains in disks around young stars: ATCA observations of WW Cha,
  RU Lup, and CS Cha

abstract:
  Grains in disks around young stars grow from interstellar submicron sizes to
planetesimals over the course of several Myr. Thermal emission of large grains
or pebbles can be best observed at cm wavelengths. However, other emission
mechanisms can contribute. We aim to determine the mechanisms of cm emission
for 3 T Tauri stars. WW Cha and RU Lup were recently found to have grain growth
at least up to mm sizes in their circumstellar disks. CS Cha has similar
indications for grain growth in its circumbinary disk. The T Tauri stars WW Cha
and RU Lup were monitored over several years at mm and cm wavelengths, using
ATCA. The new ATCA 7 mm system was also used to observe CS Cha. WW Cha was
detected on several occasions at 7 and 16 mm. We obtained one detection of WW
Cha at 3 cm and upper limits only at 6 cm. The emission at 16 mm was stable
over days, months and years, but the emission at 3 cm is found to be variable.
RU Lup was detected at 7 mm. It was observed at 16 mm 3 times and at 3 and 6 cm
4 times and found to be variable in all 3 wavebands. CS Cha was detected at 7
mm, but the S/N was too low to resolve the gap in the circumbinary disk. The
emission at 3, 7 and 16 mm for WW Cha is well explained by thermal emission
from mm and cm-sized pebbles. The cm spectral index is consistent with the
emission from an optically-thick ionised wind, but the high variability of the
cm emission points to a non-thermal contribution. The SEDs of RU Lup and CS Cha
from 1 to 7 mm are consistent with thermal emission from mm-sized grains. The
variability of the longer-wavelength emission for RU Lup and the negative
spectral index suggest non-thermal emission.


title: Theory and Phenomenology of Heavy Flavor at RHIC

abstract:
  We review the problem of heavy-quark diffusion in the Quark-Gluon Plasma and
its ramifications for heavy-quark spectra in heavy-ion collisions at RHIC. In
particular, we attempt to reconcile underlying mechanisms of several seemingly
different approaches that have been put forward to explain the large
suppression and elliptic flow of non-photonic electron spectra. We also
emphasize the importance of a quantitative description of the bulk medium
evolution to extract reliable values for the heavy-quark diffusion coefficient.


title:
Convergent finite element methods for compressible barotropic Stokes
  systems

abstract:
  We propose finite element methods for compressible barotropic Stokes systems.
We state convergence results for these methods and outline their proofs. The
principal tools of the proofs are higher integrability estimates for the
discrete density, equations for the discrete effective viscous flux, and
renormalized formulations of the numerical method for the density equation.


title:
Atomization energies of the carbon clusters Cn (n=2--10) revisited by
  means of W4 theory as well as density functional, Gn, and CBS methods

abstract:
  The thermochemistry of the carbon clusters C$_n$ (n=2--10) has been revisited
by means of W4 theory and W3.2lite theory. Particularly the larger clusters
exhibit very pronounced post-CCSD(T) correlation effects. Despite this, our
best calculated total atomization energies agree surprisingly well with 1991
estimates obtained from scaled CCD(ST)/6-31G* data. Accurately reproducing the
small singlet-triplet splitting in C$_2$ requires inclusion of connected
quintuple and sextuple excitations. Post-CCSD(T) correlation effects in C$_4$
stabilize the linear form. Linear/cyclic equilibria in C$_6$, C$_8$, and
C$_{10}$ are not strongly affected by connected quadruples, but they are
affected by higher-order triples, which favor polyacetylenic rings but disfavor
cumulenic ones. Near the CCSD(T) basis set limit, C$_{10}$ does undergo bond
angle alternation in the bottom-of-the-well structure, although it is expected
to be absent in the vibrationally averaged structure. The thermochemistry of
these systems, and particularly the longer linear chains, is a particularly
difficult test for density functional methods. Particularly for the smaller
chains and the rings, double-hybrid functionals clearly outperform convential
DFT functionals for these systems. Among compound thermochemistry schemes, G4
clearly outperforms the other members of the G$n$ family. Our best estimates
for total atomization energies at 0 K should be reliable to 1 kJ/mol up to
C$_5$ inclusive, and to better than 1 kcal/mol up to C$_9$ inclusive.


title:
Gravitational lensing of stars orbiting the Massive Black Hole in the
  Galactic Center

abstract:
  The existence of a massive black hole in the center of the Milky Way,
coinciding with the radio source Sgr A*, is being established on more and more
solid ground. In principle, this black hole, acting as a gravitational lens, is
able to bend the light emitted by stars moving within its neighborhood,
eventually generating secondary images. Extending a previous analysis of the
gravitational lensing phenomenology to a new set of 28 stars, whose orbits have
been well determined by recent observations, we have calculated all the
properties of their secondary images, including time and magnitude of their
luminosity peaks and their angular distances from the central black hole. The
best lensing candidate is represented by the star S6, since the magnitude of
its secondary image at the peak reaches K=20.8, with an angular separation of
0.3 mas from the central black hole, that is just at the borders of the
resolution limit in the K band of incoming astronomical instruments.


title: Influence of particle composition and thermal cycling on bijel formation

abstract:
  Colloidal particles with appropriate wetting properties can become very
strongly trapped at an interface between two immiscible fluids. We have
harnessed this phenomenon to create a new class of soft materials with
intriguing and potentially useful characteristics. The material is known as a
bijel: bicontinuous interfacially-jammed emulsion gel. It is a
colloid-stabilized emulsion with fluid-bicontinuous domains. The potential to
create these gels was first predicted using computer simulations.
Experimentally we use mixtures of water and 2,6-lutidine at the composition for
which the system undergoes a critical demixing transition on warming. Colloidal
silica, with appropriate surface chemistry, is dispersed while the system is in
the single-fluid phase; the composite sample is then slowly warmed well beyond
the critical temperature. The liquids phase separate via spinodal decomposition
and the particles become swept up on the newly created interfaces. As the
domains coarsen the interfacial area decreases and the particles eventually
become jammed together. The resulting structures have a significant yield
stress and are stable for many months. Here we begin to explore the complex
wetting properties of fluorescently-tagged silica surfaces in water-lutidine
mixtures, showing how they can be tuned to allow bijel creation. Additionally
we demonstrate how the particle properties change with time while they are
immersed in the solvents.


title: On the robustness of q-expectation values and Renyi entropy

abstract:
  We study the robustness of functionals of probability distributions such as
the R\'enyi and nonadditive S_q entropies, as well as the q-expectation values
under small variations of the distributions. We focus on three important types
of distribution functions, namely (i) continuous bounded (ii) discrete with
finite number of states, and (iii) discrete with infinite number of states. The
physical concept of robustness is contrasted with the mathematically stronger
condition of stability and Lesche-stability for functionals. We explicitly
demonstrate that, in the case of continuous distributions, once unbounded
distributions and those leading to negative entropy are excluded, both Renyi
and nonadditive S_q entropies as well as the q-expectation values are robust.
For the discrete finite case, the Renyi and nonadditive S_q entropies and the
q-expectation values are robust. For the infinite discrete case, where both
Renyi entropy and q-expectations are known to violate Lesche-stability and
stability respectively, we show that one can nevertheless state conditions
which guarantee physical robustness.


title: An Introduction to the Spectral Analysis of the QGP

abstract:
  This is an introduction to the study of the in-medium behavior of quarkonia
and its application to the quark-gluon plasma search in high energy nuclear
collisions.


title: Scale relativity and fractal space-time: theory and applications

abstract:
  In the first part of this contribution, we review the development of the
theory of scale relativity and its geometric framework constructed in terms of
a fractal and nondifferentiable continuous space-time. This theory leads (i) to
a generalization of possible physically relevant fractal laws, written as
partial differential equation acting in the space of scales, and (ii) to a new
geometric foundation of quantum mechanics and gauge field theories and their
possible generalisations. In the second part, we discuss some examples of
application of the theory to various sciences, in particular in cases when the
theoretical predictions have been validated by new or updated observational and
experimental data. This includes predictions in physics and cosmology (value of
the QCD coupling and of the cosmological constant), to astrophysics and
gravitational structure formation (distances of extrasolar planets to their
stars, of Kuiper belt objects, value of solar and solar-like star cycles), to
sciences of life (log-periodic law for species punctuated evolution, human
development and society evolution), to Earth sciences (log-periodic
deceleration of the rate of California earthquakes and of Sichuan earthquake
replicas, critical law for the arctic sea ice extent) and tentative
applications to system biology.


title: Evidence for nodal superconductivity in LaFePO

abstract:
  In several iron-arsenide superconductors there is strong evidence for a fully
gapped superconducting state consistent with either a conventional s-wave
symmetry or an unusual $s_\pm$ state where there the gap changes sign between
the electron and hole Fermi surface sheets. Here we report measurements of the
penetration depth $\lambda(T)$ in very clean samples of the related
iron-phosphide superconductor, LaFePO, at temperatures down to $\sim$ 100 mK.
We find that $\lambda(T)$ varies almost perfectly linearly with $T$ strongly
suggesting the presence of gap nodes in this compound. Taken together with
other data, this suggests the gap function may not be generic to all pnictide
superconductors.


title: Simulating plasma instabilities in SU(3) gauge theory

abstract:
  We compute nonequilibrium dynamics of plasma instabilities in
classical-statistical lattice gauge theory in 3+1 dimensions. The simulations
are done for the first time for the SU(3) gauge group relevant for quantum
chromodynamics. We find a qualitatively similar behavior as compared to earlier
investigations in SU(2) gauge theory. The characteristic growth rates are about
25 % lower for given energy density, such that the isotropization process is
slower. Measured in units of the characteristic screening mass, the primary
growth rate is independent of the number of colors.