title: Modelling the polarization dichotomy of Active Galactic Nuclei

abstract:
  I present polarization modelling of Active Galactic Nuclei in the optical/UV
range. The modelling is conducted using the Monte-Carlo radiative transfer code
Stokes, which self-consistently models the polarization signature of a complex
model arrangement for an active nucleus. In this work I include three different
scattering regions around the central source: an equatorial electron scattering
disk, an equatorial obscuring dusty torus, and polar electron scattering cones.
I investigate the resulting dependencies of the V-band polarization for
different optical depths of the scattering cones, different dust compositions
inside the torus, and various half-opening angles of the torus/polar cones. The
observed polarization dichotomy can be successfully reproduced by the model.


title: Asymmetric phase diagram of mixed $CuInP_2(S_xSe_{1-x})_6$ crystals

abstract:
  In this article mixed CuInP$_2$(S$_x$Se$_{1-x}$)$_6$ crystals were
investigated by broadband dielectric spectroscopy (20 Hz - 3 GHz). From these
results the complete phase diagram has been obtained. In the middle part of the
phase diagram the dipolar glass phase has been observed. The phase diagram of
investigated crystals is strongly asymmetric - the decreasing of ferroelectric
phase transition temperatures in CuInP$_2$(S$_x$Se$_{1-x}$)$_6$ is much more
flat with small admixture of sulphur then with small admixture of selenium. In
boundary region between ferroelectric order and dipolar glass disorder with
small amount of sulphur at low temperatures the nonergodic relaxor phase
appears. The phase diagram was discussed in terms of random bonds and random
fields.


title: Collisionless relaxation in non-neutral plasmas

abstract:
  A theoretical framework is presented which allows to quantitatively predict
the final stationary state achieved by a non-neutral plasma during a process of
collisionless relaxation. As a specific application, the theory is used to
study relaxation of charged-particles beams. It is shown that a fully matched
beam relaxes to the Lynden-Bell distribution. However, when a mismatch is
present and the beam oscillates, parametric resonances lead to a core-halo
phase separation. The approach developed accounts for both the density and the
velocity distributions in the final stationary state.


title: Prediction of long memory processes on same-realisation

abstract:
  For the class of stationary Gaussian long memory processes, we study some
properties of the least-squares predictor of X_{n+1} based on (X_n, ..., X_1).
The predictor is obtained by projecting X_{n+1} onto the finite past and the
coefficients of the predictor are estimated on the same realisation. First we
prove moment bounds for the inverse of the empirical covariance matrix. Then we
deduce an asymptotic expression of the mean-squared error. In particular we
give a relation between the number of terms used to estimate the coefficients
and the number of past terms used for prediction, which ensures the L^2-sense
convergence of the predictor. Finally we prove a central limit theorem when our
predictor converges to the best linear predictor based on all the past.


title:
Correspondence between the 3-form and non-minimal multiplet in
  supersymmetry

abstract:
  In analogy to the chiral-linear multiplet correspondence we establish a
relationship between the 3-form (or gaugino condensate) multiplet and a coupled
non-minimal (0,1/2) multiplet, illustrated by a simple explicit example.


title: 12CO 4-3 and [CI] 1-0 at the centers of NGC 4945 and Circinus

abstract:
  Studying molecular gas in the central regions of the star burst galaxies
NGC4945 and Circinus enables us to characterize the physical conditions and
compare them to previous local and high-z studies. We estimate temperature,
molecular density and column densities of CO and atomic carbon. Using model
predictions we give a range of estimated CO/C abundance ratios. Using the new
NANTEN2 4m sub-millimeter telescope in Pampa La Bola, Chile, we observed for
the first time CO 4-3 and [CI] 3P1-3 P0 at the centers of both galaxies at
linear scale of 682 pc and 732 pc respectively. We compute the cooling curves
of 12CO and 13CO using radiative transfer models and estimate the physical
conditions of CO and [CI]. The centers of NGC4945 and Circinus are very [CI]
bright objects, exhibiting [CI] 3P1 - 3 P0 luminosities of 91 and 67Kkms-1kpc2,
respectively. The [CI] 3P1-3 P0/CO 4-3 ratio of integrated intensities are
large at 1.2 in NGC4945 and 2.8 in Circinus. Combining previous CO J= 1-0, 2-1
and 3-2 and 13CO J= 1-0, 2-1 studies with our new observations, the radiative
transfer calculations give a range of densities, n(H2) = 10^3-3*104^cm-3, and a
wide range of kinetic temperatures, Tkin = 20 - 100K, depending on the density.
Future CO J= 7-6 and [CI] 2-1 observations will be important to resolve the
ambiguity in the physical conditions and confirm the model predictions.


title: Binding of Hypernuclei in the Latest Quark-Meson Coupling Model

abstract:
  The most recent development of the quark-meson coupling (QMC) model, in which
the effect of the mean scalar field in-medium on the hyperfine interaction is
also included self-consistently, is used to compute the properties of finite
hypernuclei. The calculations for $\Lambda$ and $\Xi$ hypernuclei are of
comparable quality to earlier QMC results without the additional parameter
needed there. Even more significantly, the additional repulsion associated with
the increased hyperfine interaction in-medium completely changes the
predictions for $\Sigma$ hypernuclei. Whereas in the earlier work they were
bound by an amount similar to $\Lambda$ hypernuclei, here they are unbound, in
qualitative agreement with the experimental absence of such states. The
equivalent non-relativistic potential felt by the $\Sigma$ is repulsive inside
the nuclear interior and weakly attractive in the nuclear surface, as suggested
by the analysis of $\Sigma$-atoms.


title: Occupation numbers from functional integral

abstract:
  Occupation numbers for non-relativistic interacting particles are discussed
within a functional integral formulation. We concentrate on zero temperature,
where the Bogoliubov theory breaks down for strong couplings as well as for low
dimensional models. We find that the leading behavior of the occupation numbers
for small momentum is governed by a quadratic time derivative in the inverse
propagator that is not contained in the Bogoliubov theory. We propose to use a
functional renormalization group equation for the occupation numbers in order
to implement systematic non-perturbative extensions beyond the Bogoliubov
theory.

categories: cond-mat.stat-mech astro-ph cond-mat.str-el hep-th nucl-th


title: Quantum Hall system in Tao-Thouless limit

abstract:
  We consider spin-polarized electrons in a single Landau level on a torus. The
quantum Hall problem is mapped onto a one-dimensional lattice model with
lattice constant $2\pi/L_1$, where $L_1$ is a circumference of the torus (in
units of the magnetic length). In the Tao-Thouless limit, $L_1\to 0$, the
interacting many-electron problem is exactly diagonalized at any rational
filling factor $\nu=p/q\le 1$. For odd $q$, the ground state has the same
qualitative properties as a bulk ($L_1 \to \infty$) quantum Hall hierarchy
state and the lowest energy quasiparticle exitations have the same fractional
charges as in the bulk. These states are the $L_1 \to 0$ limits of the
Laughlin/Jain wave functions for filling fractions where these exist. We argue
that the exact solutions generically, for odd $q$, are continuously connected
to the two-dimensional bulk quantum Hall hierarchy states, {\it ie} that there
is no phase transition as $L_1 \to \infty$ for filling factors where such
states can be observed. For even denominator fractions, a phase transition
occurs as $L_1$ increases. For $\nu=1/2$ this leads to the system being mapped
onto a Luttinger liquid of neutral particles at small but finite $L_1$, this
then develops continuously into the composite fermion wave function that is
believed to describe the bulk $\nu=1/2$ system. The analysis generalizes to
non-abelian quantum Hall states.


title: Distribution of Edge Load in Scale-free Trees

abstract:
  Node betweenness has been studied recently by a number of authors, but until
now less attention has been paid to edge betweenness. In this paper, we present
an exact analytic study of edge betweenness in evolving scale-free and
non-scale-free trees. We aim at the probability distribution of edge
betweenness under the condition that a local property, the in-degree of the
``younger'' node of a randomly selected edge, is known. En route to the
conditional distribution of edge betweenness the exact joint distribution of
cluster size and in-degree, and its one dimensional marginal distributions have
been presented in the paper as well. From the derived probability distributions
the expectation values of different quantities have been calculated. Our
results provide an exact solution not only for infinite, but for finite
networks as well.


title: Proofs of the martingale FCLT

abstract:
  This is an expository review paper elaborating on the proof of the martingale
functional central limit theorem (FCLT). This paper also reviews tightness and
stochastic boundedness, highlighting one-dimensional criteria for tightness
used in the proof of the martingale FCLT. This paper supplements the expository
review paper Pang, Talreja and Whitt (2007) illustrating the ``martingale
method'' for proving many-server heavy-traffic stochastic-process limits for
queueing models, supporting diffusion-process approximations.


title: Leptonic CP Violation and Leptogenesis

abstract:
  We review some recent results on the connection between CP violation at low
energies and Leptogenesis in the framework of specific flavour structures for
the fundamental leptonic mass matrices with zero textures.


title: Probing clumpy stellar winds with a neutron-star

abstract:
  INTEGRAL tripled the number of super-giant high-mass X-ray binaries (sgHMXB)
known in the Galaxy by revealing absorbed and fast transient (SFXT) systems.
Quantitative constraints on the wind clumping of massive stars can be obtained
from the study of the hard X-ray variability of SFXT. A large fraction of the
hard X-ray emission is emitted in the form of flares with a typical duration of
3 ksec, frequency of 7 days and luminosity of 1E36 ergs/s. Such flares are most
probably emitted by the interaction of a compact object orbiting at ~ 10 R*
with wind clumps (1E(22-23) g) representing a large fraction of the stellar
mass-loss rate. The density ratio between the clumps and the inter-clump medium
is 1E(2-4) . The parameters of the clumps and of the inter-clump medium,
derived from the SFXT flaring behavior, are in good agreement with
macro-clumping scenario and line-driven instability simulations. SFXT are
likely to have larger orbital radius than classical sgHMXB.


title: A direct and simple proof of Jacobi identities for determinants

abstract:
  The Jacobi identities play an important role in constructing the explicit
exact solutions of a broad class of integrable systems in soliton theory. In
the paper, a direct and simple proof of the Jacobi identities for determinants
is presented by employing the Pl$\ddot{u}$cker relations.


title: Recent progress on the notion of global hyperbolicity

abstract:
  Global hyperbolicity is a central concept in Mathematical Relativity. Here,
we review the different approaches to this concept explaining both, classical
approaches and recent results. The former includes Cauchy hypersurfaces, naked
singularities, and the space of the causal curves connecting two events. The
latter includes structural results on globally hyperbolic spacetimes, their
embeddability in Lorentz-Minkowski, and the recently revised notions of both,
causal and conformal boundaries. Moreover, two criteria for checking global
hyperbolicity are reviewed. The first one applies to general splitting
spacetimes. The second one characterizes accurately global hyperbolicity and
spacelike Cauchy hypersurfaces for standard stationary spacetimes, in terms of
a naturally associated Finsler metric.


title: Facilitated spin models: recent and new results

abstract:
  Facilitated or kinetically constrained spin models (KCSM) are a class of
interacting particle systems reversible w.r.t. to a simple product measure.
Each dynamical variable (spin) is re-sampled from its equilibrium distribution
only if the surrounding configuration fulfills a simple local constraint which
\emph{does not involve} the chosen variable itself. Such simple models are
quite popular in the glass community since they display some of the peculiar
features of glassy dynamics, in particular they can undergo a dynamical arrest
reminiscent of the liquid/glass transitiom. Due to the fact that the jumps
rates of the Markov process can be zero, the whole analysis of the long time
behavior becomes quite delicate and, until recently, KCSM have escaped a
rigorous analysis with the notable exception of the East model. In these notes
we will mainly review several recent mathematical results which, besides being
applicable to a wide class of KCSM, have contributed to settle some debated
questions arising in numerical simulations made by physicists. We will also
provide some interesting new extensions. In particular we will show how to deal
with interacting models reversible w.r.t. to a high temperature Gibbs measure
and we will provide a detailed analysis of the so called one spin facilitated
model on a general connected graph.

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


title:
Eliminating spin contamination in auxiliary-field quantum Monte Carlo:
  realistic potential energy curve of F2

abstract:
  The use of an approximate reference state wave function |Phi_r> in electronic
many-body methods can break the spin symmetry of Born-Oppenheimer
spin-independent Hamiltonians. This can result in significant errors,
especially when bonds are stretched or broken. A simple spin-projection method
is introduced for auxiliary-field quantum Monte Carlo (AFQMC) calculations,
which yields spin-contamination-free results, even with a spin-contaminated
|Phi_r>. The method is applied to the difficult F2 molecule, which is unbound
within unrestricted Hartree-Fock (UHF). With a UHF |Phi_r>, spin contamination
causes large systematic errors and long equilibration times in AFQMC in the
intermediate, bond-breaking region. The spin-projection method eliminates these
problems, and delivers an accurate potential energy curve from equilibrium to
the dissociation limit using the UHF |Phi_r>. Realistic potential energy curves
are obtained with a cc-pVQZ basis. The calculated spectroscopic constants are
in excellent agreement with experiment.


title: Semi-parametric estimation of shifts

abstract:
  We observe a large number of functions differing from each other only by a
translation parameter. While the main pattern is unknown, we propose to
estimate the shift parameters using $M$-estimators. Fourier transform enables
to transform this statistical problem into a semi-parametric framework. We
study the convergence of the estimator and provide its asymptotic behavior.
Moreover, we use the method in the applied case of velocity curve forecasting.


title: Model-Independent Bound on the Dark Matter Lifetime

abstract:
  If dark matter (DM) is unstable, in order to be present today, its lifetime
needs to be longer than the age of the Universe, t_U ~ 4 10^{17} s. It is
usually assumed that if DM decays it would do it with some strength through a
radiative mode. In this case, very constraining limits can be obtained from
observations of the diffuse gamma ray background. However, although reasonable,
this is a model-dependent assumption. Here our only assumption is that DM
decays into, at least, one Standard Model (SM) particle. Among these, neutrinos
are the least detectable ones. Hence, if we assume that the only SM decay
daughters are neutrinos, a limit on their flux from DM decays in the Milky Way
sets a conservative, but stringent and model-independent bound on its lifetime.


title:
The $\sigma K$ coupling in the chiral unitary approach and the isoscalar
  $\bar{K}N$, $\bar{K}A$ interaction

abstract:
  We evaluate the "$\sigma$" exchange contribution to the $\bar{K}N\to\bar{K}N$
scattering within a chiral unitary approach. We show that the chiral transition
potentials for $\pi \pi \to K \bar{K}$ in the $t$-channel lead to a "$\sigma$"
contribution that vanishes in the $\bar{K}$ forward direction and, hence, would
produce a null "$\sigma$" exchange contribution to the $K^-$ optical potential
in nuclear matter in a simple impulse approximation. This is a consequence of
the fact that the leading order chiral Lagrangian gives an I=0 $\pi\pi\to
K\bar{K}$ amplitude proportional to the squared momentum transfer, $q^2$. This
finding poses questions on the meaning or the origin of "$\sigma$" exchange
potentials used in relativistic mean field approaches to the $K^-$ nuclear
selfenergy. This elementary "$\sigma$" exchange potential in
$\bar{K}N\to\bar{K}N$ is compared to the Weinberg-Tomozawa term and is found to
be smaller than present theoretical uncertainties but will be relevant in the
future when aiming at fitting increasingly more accurate data.


title: Designs, groups and lattices

abstract:
  We study the Grassmannian 4-designs contained in lattices, in connection with
the local property of the Rankin constant. We prove that the sequence of
Barnes-Wall lattices contain Grassmannian 6-designs.


title: Generalised integrable Hubbard models

abstract:
  We construct the XX and Hubbard-like models based on unitary superalgebras
gl(N|M) generalizing Shastry's and Maassarani's approach. We introduce the
R-matrix of the gl(N|M) XX-type model; the one of the Hubbard-like model is
defined by "coupling" two independent XX models. In both cases, we show that
the R-matrices satisfy the Yang-Baxter equation. We derive the corresponding
local Hamiltonian in the transfer matrix formalism and we determine its
symmetries. A perturbative calculation "\`a la Klein and Seitz" is performed.
Some explicit examples are worked out. We give a description of the
two-particle scattering.


title: Multiple Scattering, Underlying Event, and Minimum Bias

abstract:
  In this talk I first discuss the experimental evidence for multiple
scattering and the properties of the underlying event. The extensive analyses
by Rick Field of data from CDF cannot be reconciled with traditional wisdom
concerning multiple collisions and the AGK cutting rules. Data seem to imply
some kind of color recombination or unexpectedly strong effects from pomeron
vertices. I then discuss theoretical ideas concerning the relation between
multiple collisions and unitarity: the AGK rules, IP loops, dipole cascade
models and diffraction.


title: Avalanche to streamer transition in particle simulations

abstract:
  The avalanche to streamer transition is studied and illustrated in a particle
model. The results are similar to those of fluid models. However, when
super-particles are introduced, numerical artefacts become visible. This
underscores the need of models that are hybrid in space.


title:
Improving population-specific allele frequency estimates by adapting
  supplemental data: an empirical Bayes approach

abstract:
  Estimation of the allele frequency at genetic markers is a key ingredient in
biological and biomedical research, such as studies of human genetic variation
or of the genetic etiology of heritable traits. As genetic data becomes
increasingly available, investigators face a dilemma: when should data from
other studies and population subgroups be pooled with the primary data? Pooling
additional samples will generally reduce the variance of the frequency
estimates; however, used inappropriately, pooled estimates can be severely
biased due to population stratification. Because of this potential bias, most
investigators avoid pooling, even for samples with the same ethnic background
and residing on the same continent. Here, we propose an empirical Bayes
approach for estimating allele frequencies of single nucleotide polymorphisms.
This procedure adaptively incorporates genotypes from related samples, so that
more similar samples have a greater influence on the estimates. In every
example we have considered, our estimator achieves a mean squared error (MSE)
that is smaller than either pooling or not, and sometimes substantially
improves over both extremes. The bias introduced is small, as is shown by a
simulation study that is carefully matched to a real data example. Our method
is particularly useful when small groups of individuals are genotyped at a
large number of markers, a situation we are likely to encounter in a
genome-wide association study.


title:
The Simulation of High Pressure Nucleation Experiments in Diffusion
  Cloud Chamber

abstract:
  For high- pressure nucleation experiments in upward diffusion cloud chamber,
there is the great deviation of predictions of classical nucleation theory from
experimental results; the discrepancy is more than 10 orders of magnitude of
nucleation rate. Experimental data for 1-propanol vapor are under investigation
in this paper. It was shown that mathematical model of a single droplet growth
and motion semi- quantitatively explained all experimentally discovered
regularities. For explanations low nucleation rate versus high supersaturation,
the coalescence mechanism in gaseous phase has been proposed. As result of
coalescence the vast majority of newly formed clusters evaporate and restore
vapor density and temperature profile in DCC. The observed picture with low
nucleation rate is result of diffusion interaction between small clusters and
droplets in nucleation zone for high- pressure nucleation experiments.


title:
Correlations between political party size and voter memory: A
  statistical analysis of opinion polls

abstract:
  This paper describes the application of statistical methods to political
polling data in order to look for correlations and memory effects. We propose
measures for quantifying the political memory using the correlation function
and scaling analysis. These methods reveal time correlations and self-affine
scaling properties respectively, and they have been applied to polling data
from Norway. Power-law dependencies have been found between correlation
measures and party size, and different scaling behaviour has been found for
large and small parties.


title:
Gravitational Lensing Statistics by Galaxy Clusters with Smoothness
  Parameter Depending on z

abstract:
  Using the Eikonal approximation we study the effect of the smoothness
parameter in the Dyer-Roeder equation. We calculate the optical depth for dark
halos with NFW profile, for the abundance the Press-Schechter formalism is
used. We focus our analysis on the cross section for multiple images (three).
Different cosmologies are compared.


title: Generalized Parton Distrbutions and Nucleon Form Factors

abstract:
  The Dirac and Pauli form factors of the proton and neutron are obtained in
the framework of the generalized parton distributions (GPDs) with some simple
momentum transfer dependence. It is shown that both sets of the existing
experimental data of the form factors, obtained by the Rosenbluth and
polarization transfer, can be described by changing only the slope of the GPDs
$E$. The description of neutron form factors is substantially better when the
proton data obtained by the studies of polarization transfer are used.


title: Constraining Walking and Custodial Technicolor

abstract:
  We show how to constrain the physical spectrum of walking technicolor models
via precision measurements and modified Weinberg sum rules. We also study
models possessing a custodial symmetry for the S parameter at the effective
Lagrangian level - custodial technicolor - and argue that these models cannot
emerge from walking type dynamics. We suggest that it is possible to have a
very light spin-one axial vector boson. However, in the walking dynamics the
associated vector boson is heavy while it is degenerate with the axial in
custodial technicolor.


title:
Special Relativistic Simulations of Magnetically-dominated Jets in
  Collapsing Massive Stars

abstract:
  We perform a series of two-dimensional magnetohydrodynamic core-collapse
simulations of rapidly rotating and strongly magnetized massive stars. To study
the properties of magnetic explosions for a longer time stretch of postbounce
evolution, we develop a new code under the framework of special relativity
including a realistic equation of state with a multiflavor neutrino leakage
scheme. Our results show the generation of the magnetically-dominated jets in
the two ways. One is launched just after the core-bounce in a prompt way and
another is launched at $ \sim 100 $ ms after the stall of the prompt shock. We
find that the shock-revival occurs when the magnetic pressure becomes strong,
due to the field wrapping, enough to overwhelm the ram pressure of the
accreting matter. The critical toroidal magnetic fields for the magnetic
shock-revival are found to be universal of $\sim 10^{15}\mathrm{G}$ behind the
jets. We point out that the time difference before the shock-revival has a
strong correlation with the explosions energies. Our results suggest that the
magnetically dominated jets are accompanied by the formation of the magnetars.
Since the jets are mildly relativistic, we speculate that they might be the
origin of some observed X-ray flashes.


title: ILC Reference Design Report Volume 1 - Executive Summary

abstract:
  The International Linear Collider (ILC) is a 200-500 GeV center-of-mass
high-luminosity linear electron-positron collider, based on 1.3 GHz
superconducting radio-frequency (SCRF) accelerating cavities. The ILC has a
total footprint of about 31 km and is designed for a peak luminosity of 2x10^34
cm^-2s^-1. This report is the Executive Summary (Volume I) of the four volume
Reference Design Report. It gives an overview of the physics at the ILC, the
accelerator design and value estimate, the detector concepts, and the next
steps towards project realization.


title: Scaling limit and aging for directed trap models

abstract:
  We consider one-dimensional directed trap models and suppose that the
trapping times are heavy-tailed. We obtain the inverse of a stable subordinator
as scaling limit and prove an aging phenomenon expressed in terms of the
generalized arcsine law. These results confirm the status of universality
described by Ben Arous and \v{C}ern\'y for a large class of graphs.


title: LERW as an example of off-critical SLEs

abstract:
  Two dimensional loop erased random walk (LERW) is a random curve, whose
continuum limit is known to be a Schramm-Loewner evolution (SLE) with parameter
kappa=2. In this article we study ``off-critical loop erased random walks'',
loop erasures of random walks penalized by their number of steps. On one hand
we are able to identify counterparts for some LERW observables in terms of
symplectic fermions (c=-2), thus making further steps towards a field theoretic
description of LERWs. On the other hand, we show that it is possible to
understand the Loewner driving function of the continuum limit of off-critical
LERWs, thus providing an example of application of SLE-like techniques to
models near their critical point. Such a description is bound to be quite
complicated because outside the critical point one has a finite correlation
length and therefore no conformal invariance. However, the example here shows
the question need not be intractable. We will present the results with emphasis
on general features that can be expected to be true in other off-critical
models.


title: Decay b -> (c\bar{c}) s in the leading logarithm approximation

abstract:
  We consider an effective field theory for the nonleptonic decay in which a
heavy quark decays into a pair of a heavy quark and antiquark having a small
relative velocity and one relativistic (massless) quark. This effective theory
is a combination of HQET, SCET, and a covariant modification of NRQCD. In the
leading logarithm approximation the effective theory decay amplitude factorizes
into the product of matrix elements of heavy-to-heavy and heavy-to-light
currents. We discuss a possibility of factorization beyond the leading
logarithm approximation and find it doubtful. The Wilson coefficients of the
effective theory electro-weak (EWET) Lagrangian in the next-to-the leading
logarithm approximation are calculated at the matching scale of the decay. The
differential decay rate for the inclusive decay B -> J/\psi+h in the effective
theory framework is evaluated.


title:
Higher derivative corrections to Wess-Zumino action of Brane-Antibrane
  systems

abstract:
  By explicit calculation, we show that the expansion of the disk level
S-matrix element of one RR field, two open string tachyons and one gauge field
that has been recently found corresponds to the derivative expansion of the
Wess-Zumino action of D-brane-anti-D-brane systems.


title:
Electric field effect on electron spin splitting in SiGe/Si quantum
  wells

abstract:
  Effect of electric field on spin splitting in SiGe quantum wells (QWs) has
been studied theoretically. Microscopical calculations of valley and spin
splittings are performed in the effective $sp^3d^5s^*$ tight-binding model. The
splittings oscillate as a function of the QW width due to inter-valley
reflection of the electron wave off the interfaces. In accordance with the
symmetry considerations additional electric-field-induced terms appear in the
electron spin-dependent Hamiltonian. The oscillations of splitting are
suppressed in rather low electric fields. The tight-binding calculations have
been analyzed by using the envelope function approach extended to asymmetrical
QWs.


title: Discovery of The New WZ Sge Star, SDSS J080434.20+510349.2

abstract:
  We present the results of photometric observations of SDSS
J080434.20+510349.2 in its low state and during an outburst and spectroscopy
during the outburst. We found such peculiarities as a long-term outburst with
amplitude probably not less than 6m, rarity of the outbursts, eleven
rebrightenings, and a short (0.059713(7) d) superhump period. We conclude that
this star belongs to the WZ Sge-type subclass of cataclysmic variables. The
spectrum shows both emission and absorption lines of H and He superimposed on
the blue continuum. We also found 8 -- 9 min. brightness variations during the
end of the super-outburst plateau that could be related to pulsations of the
white dwarf in the binary.


title:
Brauer-Manin obstruction for integral points of homogeneous spaces and
  representation by integral quadratic forms

abstract:
  An integer may be represented by a quadratic form over each ring of p-adic
integers and over the reals without being represented by this quadratic form
over the integers. More generally, such failure of a local-global principle may
occur for the representation of one integral quadratic form by another integral
quadratic form. We show that many such examples may be accounted for by a
Brauer-Manin obstruction for the existence of integral points on schemes
defined over the integers. For several types of homogeneous spaces of linear
algebraic groups, this obstruction is shown to be the only obstruction to the
existence of integral points.
  -----
  Une forme quadratique enti\`ere peut \^etre repr\'esent\'ee par une autre
forme quadratique enti\`ere sur tous les anneaux d'entiers p-adiques et sur les
r\'eels, sans l'\^etre sur les entiers. On en trouve de nombreux exemples dans
la litt\'erature. Nous montrons qu'une partie de ces exemples s'explique au
moyen d'une obstruction de type Brauer-Manin pour les points entiers. Pour
plusieurs types d'espaces homog\`enes de groupes alg\'ebriques lin\'eaires,
cette obstruction est la seule obstruction \`a l'existence d'un point entier.


title: Velocity Fields in the Solar Photosphere

abstract:
  Large-scale velocity fields in the solar photosphere remain a mystery in
spite of many years of intensive studies. In this thesis, the new method of the
measurements of the solar photospheric flow fields is proposed. It is based on
local correlation tracking algorithm applied to full-disc dopplergrams obtained
by Michelson Doppler Images (MDI) on-board the Solar and Heliospheric
Observatory (SoHO). The method is tuned and tested on synthetic data, it is
shown that the method is capable of measuring of horizontal velocity fields
with an accuracy of 15 \mps. It is also shown that the method provides the
measurements comparable with time-distance local helioseismology. The method is
applied to real data sets. It reproduces well known properties of solar
photospheric velocity fields. Moreover, the case studies show an evidence about
the influence of the changes in the flow field topology on the stability of the
eruptive filament and support the theory of the dynamical disconnection of
bipolar sunspots from their magnetic roots. The method has a great perspective
in the future use. The meridional flux transportation speed is also studied and
it is shown that the direct measurement may differ from time-distance local
helioseimology in the areas occupied by the strong magnetic field. This result
has an impact to the flux transport dynamo models, which use the meridional
speed as the essential observational input parameter.


title: Delaunay Edge Flips in Dense Surface Triangulations

abstract:
  Delaunay flip is an elegant, simple tool to convert a triangulation of a
point set to its Delaunay triangulation. The technique has been researched
extensively for full dimensional triangulations of point sets. However, an
important case of triangulations which are not full dimensional is surface
triangulations in three dimensions. In this paper we address the question of
converting a surface triangulation to a subcomplex of the Delaunay
triangulation with edge flips. We show that the surface triangulations which
closely approximate a smooth surface with uniform density can be transformed to
a Delaunay triangulation with a simple edge flip algorithm. The condition on
uniformity becomes less stringent with increasing density of the triangulation.
If the condition is dropped completely, the flip algorithm still terminates
although the output surface triangulation becomes "almost Delaunay" instead of
exactly Delaunay.


title: The Network of Commuters in London

abstract:
  We study the directed and weighted network in which the wards of London are
vertices and two vertices are connected whenever there is at least one person
commuting to work from a ward to another. Remarkably the in-strength and
in-degree distribution tail is a power law with exponent around -2, while the
out-strength and out-degree distribution tail is exponential. We propose a
simple square lattice model to explain the observed empirical behaviour.


title: Dirichlet branes and a cohomological definition of time flow

abstract:
  Dirichlet branes are objects whose transverse coordinates in space are
matrix-valued functions. This leads to considering a matrix algebra or, more
generally, a Lie algebra, as the classical phase space of a certain dynamics
where the multiplication of coordinates, being given by matrix multiplication,
is nonabelian. Further quantising this dynamics by means of a star-product
introduces noncommutativity (besides nonabelianity) as a quantum h-deformation.
The algebra of functions on a standard Poisson manifold is replaced with the
universal enveloping algebra of the given Lie algebra. We define generalised
Poisson brackets on this universal enveloping algebra, examine their
properties, and conclude that they provide a natural framework for dynamical
setups (such as coincident Dirichlet branes) where coordinates are
matrix-valued, rather than number-valued, functions.


title: The BARISTA: A model for bid arrivals in online auctions

abstract:
  The arrival process of bidders and bids in online auctions is important for
studying and modeling supply and demand in the online marketplace. A popular
assumption in the online auction literature is that a Poisson bidder arrival
process is a reasonable approximation. This approximation underlies theoretical
derivations, statistical models and simulations used in field studies. However,
when it comes to the bid arrivals, empirical research has shown that the
process is far from Poisson, with early bidding and last-moment bids taking
place. An additional feature that has been reported by various authors is an
apparent self-similarity in the bid arrival process. Despite the wide evidence
for the changing bidding intensities and the self-similarity, there has been no
rigorous attempt at developing a model that adequately approximates bid
arrivals and accounts for these features. The goal of this paper is to
introduce a family of distributions that well-approximate the bid time
distribution in hard-close auctions. We call this the BARISTA process (Bid
ARrivals In STAges) because of its ability to generate different intensities at
different stages. We describe the properties of this model, show how to
simulate bid arrivals from it, and how to use it for estimation and inference.
We illustrate its power and usefulness by fitting simulated and real data from
eBay.com. Finally, we show how a Poisson bidder arrival process relates to a
BARISTA bid arrival process.


title:
The role of the Weibel instability at the reconnection jet front in
  relativistic pair plasma reconnection

abstract:
  The role of the Weibel instability is investigated for the first time in the
context of the large-scale magnetic reconnection problem. A late-time evolution
of magnetic reconnection in relativistic pair plasmas is demonstrated by
particle-in-cell (PIC) simulations. In the outflow regions, powerful
reconnection jet piles up the magnetic fields and then a tangential
discontinuity appears there. Further downstream, it is found that the
two-dimensional extension of the relativistic Weibel instability generates
electro-magnetic fields, which are comparable to the anti-parallel or piled-up
fields. In a microscopic viewpoint, the instability allows plasma's multiple
interactions with the discontinuity. In a macroscopic viewpoint, the
instability leads to rapid expansion of the current sheet and then the
reconnection jet front further propagates into the downstream. Possible
application to the three-dimensional case is briefly discussed.


title: The Fast Read-out System for the MAPMTs of COMPASS RICH-1

abstract:
  A fast readout system for the upgrade of the COMPASS RICH detector has been
developed and successfully used for data taking in 2006 and 2007. The new
readout system for the multi-anode PMTs in the central part of the photon
detector of the RICH is based on the high-sensitivity MAD4
preamplifier-discriminator and the dead-time free F1-TDC chip characterized by
high-resolution. The readout electronics has been designed taking into account
the high photon flux in the central part of the detector and the requirement to
run at high trigger rates of up to 100 kHz with negligible dead-time. The
system is designed as a very compact setup and is mounted directly behind the
multi-anode photomultipliers. The data are digitized on the frontend boards and
transferred via optical links to the readout system. The read-out electronics
system is described in detail together with its measured performances.


title:
Oscillator-Morse-Coulomb mappings and algebras for constant or
  position-dependent mass

abstract:
  The bound-state solutions and the su(1,1) description of the $d$-dimensional
radial harmonic oscillator, the Morse and the $D$-dimensional radial Coulomb
Schr\"odinger equations are reviewed in a unified way using the point canonical
transformation method. It is established that the spectrum generating su(1,1)
algebra for the first problem is converted into a potential algebra for the
remaining two. This analysis is then extended to Schr\"odinger equations
containing some position-dependent mass. The deformed su(1,1) construction
recently achieved for a $d$-dimensional radial harmonic oscillator is easily
extended to the Morse and Coulomb potentials. In the last two cases, the
equivalence between the resulting deformed su(1,1) potential algebra approach
and a previous deformed shape invariance one generalizes to a
position-dependent mass background a well-known relationship in the context of
constant mass.


title: Universal Behavior of Two-Dimensional 3He at Low Temperatures

abstract:
  On the example of two-dimensional (2D) 3He we demonstrate that the main
universal features of its experimental temperature T - density x phase diagram
[see M. Neumann, J. Ny\'{e}ki, J. Saunders, Science 317, 1356 (2007)] look like
those in the heavy-fermion metals. Our comprehensive theoretical analysis of
experimental situation in 2D 3He allows us to propose a simple expression for
effective mass M^*(T,x), describing all diverse experimental facts in 2D 3He in
unified manner and demonstrating that the universal behavior of M^*(T,x)
coincides with that observed in HF metals.


title:
Subleading contributions to the chiral three-nucleon force I: long-range
  terms

abstract:
  We derive the long-range contributions to the tree-nucleon force at
next-to-next-to-next-to-leading order in the chiral expansion. We give both
momentum and coordinate space representations.


title: Foundations for abstract forcing

abstract:
  The foundations of forcing theory are reworked to streamline the presentation
and to show how the most basic results are applicable in very general contexts.


title: Delta-excitations and the three-nucleon force

abstract:
  We study the three-nucleon force in chiral effective field theory with
explicit Delta-resonance degrees of freedom. We show that up to
next-to-next-to-leading order, the only contribution to the isospin symmetric
three-nucleon force involving the spin-3/2 degrees of freedom is given by the
two-pion-exchange diagram with an intermediate delta, frequently called the
Fujita-Miyazawa force. We also analyze the leading isospin-breaking corrections
due to the delta. For that, we give the first analysis of the delta quartet
mass splittings in chiral effective field theory. The charge-symmetry breaking
three-nucleon force due to an intermediate delta excitation is small, of the
order of a few keV.


title: Morphogenesis of growing soft tissues

abstract:
  Recently, much attention has been given to a noteworthy property of some soft
tissues: their ability to grow. Many attempts have been made to model this
behaviour in biology, chemistry and physics. Using the theory of finite
elasticity, Rodriguez has postulated a multiplicative decomposition of the
geometric deformation gradient into a growth-induced part and an elastic one
needed to ensure compatibility of the body. In order to fully explore the
consequences of this hypothesis, the equations describing thin elastic objects
under finite growth are derived. Under appropriate scaling assumptions for the
growth rates, the proposed model is of the Foppl-von Karman type. As an
illustration, the circumferential growth of a free hyperelastic disk is
studied.


title: Quadratic algebras and position-dependent mass Schr\"odinger equations

abstract:
  During recent years, exact solutions of position-dependent mass Schr\"odinger
equations have inspired intense research activities, based on the use of point
canonical transformations, Lie algebraic methods or supersymmetric quantum
mechanical techniques. Here we highlight the interest of another approach to
such problems, relying on quadratic algebras. We illustrate this point by
constructing spectrum generating algebras for a class of $d$-dimensional radial
harmonic oscillators with $d\ge2$ (including the one-dimensional oscillator on
the line via some minor changes) and a specific mass choice. This provides us
with a counterpart of the well-known su(1,1) Lie algebraic approach to the
constant-mass oscillators.


title: Symbolic representation and classification of integrable systems

abstract:
  This is a review paper of recent results in the perturbative symmetry
approach in the symbolic representation.


title:
Conformational equilibria in monomeric alpha-synuclein at the single
  molecule level

abstract:
  Natively unstructured proteins defy the classical "one sequence-one
structure" paradigm of protein science. Monomers of these proteins in
pathological conditions can aggregate in the cell, a process that underlies
socially relevant neurodegenerative diseases such as Alzheimer and Parkinson. A
full comprehension of the formation and structure of the so-called misfolded
intermediates from which the aggregated states ensue is still lacking. We
characterized the folding and the conformational diversity of alpha-synuclein
(aSyn), a natively unstructured protein involved in Parkinson disease, by
mechanically stretching single molecules of this protein and recording their
mechanical properties. These experiments permitted us to directly observe
directly and quantify three main classes of conformations that, under in vitro
physiological conditions, exist simultaneously in the aSyn sample, including
disordered and "beta-like" structures. We found that this class of "beta-like"
structures is directly related to aSyn aggregation. In fact, their relative
abundance increases drastically in three different conditions known to promote
the formation of aSyn fibrils: the presence of Cu2+, the occurrence of the
pathogenic A30P mutation, and high ionic strength. We expect that a critical
concentration of aSyn with a "beta-like" structure must be reached to trigger
fibril formation. This critical concentration is therefore controlled by a
chemical equilibrium. Novel pharmacological strategies can now be tailored to
act upstream, before the aggregation process ensues, by targeting this
equilibrium. To this end, Single Molecule Force Spectroscopy can be an
effective tool to tailor and test new pharmacological agents.


title: On the calculation of the Casimir forces

abstract:
  Casimir forces are a manifestation of the change in the zero-point energy of
the vacuum caused by the insertion of boundaries. We show how the Casimir force
can be computed by consideration of the vacuum fluctuations that are suppressed
by the boundaries, and rederive the scalar Casimir effects for a series of
geometries. For the planar case a finite universal force is automatically
found. For curved geometries formally divergent expressions are encountered
which we argue are largely due to the divergent self-energy of the boundary
contributing to the force. This idea is supported by computing the effect for a
fixed perimeter wedge-arc geometry in two dimensions.

categories: cond-mat.stat-mech cond-mat.other hep-th quant-ph


title: Reentrant spin glass transition in LuFe2O4

abstract:
  We have carried out a comprehensive investigation of magnetic properties of
LuFe$_2$O$_4$, using AC susceptibility, DC magnetization and specific heat. A
magnetic phase transition around $\sim$236 K was observed with DC magnetization
and specific heat measurements, which is identified as a paramagnetic to
ferrimagnetic transition based on the nonlinear susceptibility data. Upon
further cooling below this temperature, we also observed highly relaxational
magnetic behavior: the DC magnetization exhibits history and time dependence,
and the real and imaginary part of the AC susceptibility shows large frequency
dependence. Dynamic scaling of the AC susceptibility data suggests that this
low temperature phase can be described as a reentrant spin glass phase. We also
discuss magnetic field dependence of the spin glass transition and aging,
memory and rejuvenation effect below the glass transition temperature around
228 K.


title: Scaling of entanglement support for Matrix Product States

abstract:
  The power of matrix product states to describe infinite-size
translational-invariant critical spin chains is investigated. At criticality,
the accuracy with which they describe ground state properties of a system is
limited by the size $\chi$ of the matrices that form the approximation. This
limitation is quantified in terms of the scaling of the half-chain entanglement
entropy. In the case of the quantum Ising model, we find $S \sim {1/6}\log
\chi$ with high precision. This result can be understood as the emergence of an
effective finite correlation length $\xi_\chi$ ruling of all the scaling
properties in the system. We produce five extra pieces of evidence for this
finite-$\chi$ scaling, namely, the scaling of the correlation length, the
scaling of magnetization, the shift of the critical point, and the scaling of
the entanglement entropy for a finite block of spins. All our computations are
consistent with a scaling relation of the form $\xi_\chi\sim \chi^{\kappa}$,
with $\kappa=2$ for the Ising model. In the case of the Heisenberg model, we
find similar results with the value $\kappa\sim 1.37$. We also show how
finite-$\chi$ scaling allow to extract critical exponents. These results are
obtained using the infinite time evolved block decimation algorithm which works
in the thermodynamical limit and are verified to agree with density matrix
renormalization group results.


title: A magnetized completion of the $\Lambda$CDM paradigm

abstract:
  The standard $\Lambda$CDM paradigm is complemented with a magnetized
contribution whose effects on the anisotropies of the Cosmic Microwave
Background (CMB) are assessed by means of a dedicated numerical approach. The
accuracy on the temperature and polarization correlations stems from the
inclusion of the large-scale magnetic fields both at the level of the initial
conditions and at the level of the Einstein-Boltzmann hierarchy which is
consistently embedded in a generalized magnetohydrodynamical framework.
Examples of the calculations of the temperature and polarization angular power
spectra are illustrated and discussed. The reported results and the described
numerical tools set the ground for a consistent inclusion of a magnetized
contribution in current strategies of cosmological parameter estimation.


title: The Symplectic Penrose Kite

abstract:
  The purpose of this article is to view the Penrose kite from the perspective
of symplectic geometry.


title: Quantum Error Correcting Codes Using Qudit Graph States

abstract:
  Graph states are generalized from qubits to collections of $n$ qudits of
arbitrary dimension $D$, and simple graphical methods are used to construct
both additive and nonadditive quantum error correcting codes. Codes of distance
2 saturating the quantum Singleton bound for arbitrarily large $n$ and $D$ are
constructed using simple graphs, except when $n$ is odd and $D$ is even.
Computer searches have produced a number of codes with distances 3 and 4, some
previously known and some new. The concept of a stabilizer is extended to
general $D$, and shown to provide a dual representation of an additive graph
code.


title: Symmetry Breaking in Six Dimensional Flux Compactification Scenarios

abstract:
  Motivated by the electroweak hierarchy problem, we consider theories with two
extra dimensions in which the four-dimensional scalar fields are components of
gauge boson in full space, namely the Gauge-Higgs unification framework. We
briefly explain the basics features of "flux compactification", i.e.
compactification in presence of a background (magnetic) flux. In particular we
recall how chirality and symmetry breaking can be obtained in this context.
More in details, we find and catalogue all possible degenerate zero-energy
stable configurations in the case of trivial or non-trivial 't Hooft flux, for
a SU(N) gauge theory on a torus. We describe the residual symmetries of each
vacua and the four-dimensional effective spectrum in terms of continuous and
discrete parameters, respectively.


title:
Seismological studies of ZZ Ceti stars. I. The model grid and the
  application to individual stars

abstract:
  We calculate and explore an extensive adiabatic model grid for pulsating
white dwarfs with H dominated atmospheres, the ZZ Ceti stars. We also compared
the computed modes with the observed ones for five ZZ Ceti stars that are a
representative sample of the whole class of pulsators. We describe our new
approach for seismological studies, using the relative observed amplitudes to
give weights for the periods in the fit and the external mass and temperature
determinations as a guide. Our seismological study is clear evidence that
seismology is indeed a powerful tool in the study of stellar structure and
evolution.


title: Low mass dilepton radiation at RHIC

abstract:
  In this work we discuss the emission of low mass dilepton radiation from a
hydrodynamic evolution model of Au-Au collisions and make comparisons with
recent PHENIX measurements. The dilepton emission rates from the hadronic phase
are treated at finite temperature and baryon density and are completely
constrained by broken chiral symmetry in a density expansion. The rates are
expressed in terms of vacuum correlators which are measured in $e^+e^-$
annihilation, $\tau$ decays and photo-reactions on nucleons and nuclei. We
consider two possibilities for the hadronic phase: A chemical equilibrated an
off equilibrium hadronic gas. We find that while chemical off-equilibrium helps
explain part of the low mass (0.15 $\leq$ M GeV $\leq$ 0.7) enhancement seen in
the data there is still a large discrepancy.


title: RZ Cassiopeia: Eclipsing Binary with Pulsating Component

abstract:
  We report time-resolved VR-band CCD photometry of the eclipsing binary RZ Cas
obtained with 38-cm Cassegrain telescope at the Crimean Astrophysical
Observatory during July 2004 - October 2005. Obtained lightcurves clearly
demonstrates rapid pulsations with the period about 22 minutes. Periodogram
analysis of such oscillations also is reported. On the 12, January, 2005 we
observed rapid variability with higher amplitude (~0.^m 1) that, perhaps, may
be interpreted as high-mass-transfer-rate event and inhomogeneity of accretion
stream. Follow-up observations (both, photometric and spectroscopic) of RZ Cas
are strictly desirable for more detailed study of such event.


title:
Applications of the Characteristic Theory to the Madelung-de
  Broglie-Bohm System of Partial Differential Equations: The Guiding Equation
  as the Characteristic Velocity

abstract:
  First, we use the theory of characteristics of first order partial
differential equations to derive the guiding equation directly from the Quantum
Evolution Equation (QEE). After obtaining the general result, we apply it to a
set of evolution equations (Schroedinger, Pauli, Klein-Gordon, Dirac) to show
how the guiding equation is, actually, the characteristic velocity of the
corresponding matter field equations.


title: The G-dwarf problem in the Galaxy

abstract:
  The empirical differential metallicity distribution (EDMD) is deduced for (i)
local thick disk stars; (ii) likely metal-weak thick disk stars; (iii)
chemically selected local G dwarfs, with the corrections performed in order to
take into account the stellar scale height; in addition to previous results
related to (iv) solar neighbourhood halo subdwarfs; and (v) K-giant bulge
stars. The thick disk is conceived as made of two distinct regions: the
halo-like and the bulge-like thick disk, and the related EDMD is deduced. Under
the assumption that each distribution is typical for the corresponding
subsystem, the EDMD of the thick disk, the thick + thin disk, and the Galaxy,
is determined by weighting the mass. Models of chemical evolution are computed
for each subsystem assuming the instantaneous recycling approximation. The EDMD
data are reasonably fitted by simple models implying both homogeneous and
inhomogeneous star formation, provided that star formation is inhibited during
thick disk evolution. The initial mass function (IMF) is assumed to be a
universal power law, which implies an unchanged true yield in different
subsystems. The theoretical differential metallicity distribution (TDMD) is
first determined for the halo-like thich disk, the bulge-like thick disk, and
the thin disk separately, and then for the Galaxy by weighting the mass. An
indicative comparison is performed between the EDMD deduced for the disk both
in presence and in absence of [O/Fe] plateau, and its counterpart computed for
(vi) nearby stars for which the oxygen abundance has been determined both in
presence and in absence of the local thermodynamical equilibrium (LTE)
approximation. Both distributions are found to exhibit a similar trend, though
systematic differences exist.


title: Three-body decays of sleptons in models with non-universal Higgs masses

abstract:
  We compute the three-body decays of charged sleptons and sneutrinos into
other sleptons. These decays are of particular interest in SUSY-breaking models
with non-universal Higgs mass parameters, where the left-chiral sleptons can be
lighter than the right-chiral ones, and lighter than the lightest neutralino.
We present the formulas for the three-body decay widths together with a
numerical analysis in the context of gaugino-mediated SUSY breaking with a
gravitino LSP.


title:
A New Outer Bound and the Noisy-Interference Sum-Rate Capacity for
  Gaussian Interference Channels

abstract:
  A new outer bound on the capacity region of Gaussian interference channels is
developed. The bound combines and improves existing genie-aided methods and is
shown to give the sum-rate capacity for noisy interference as defined in this
paper. Specifically, it is shown that if the channel coefficients and power
constraints satisfy a simple condition then single-user detection at each
receiver is sum-rate optimal, i.e., treating the interference as noise incurs
no loss in performance. This is the first concrete (finite signal-to-noise
ratio) capacity result for the Gaussian interference channel with weak to
moderate interference. Furthermore, for certain mixed (weak and strong)
interference scenarios, the new outer bounds give a corner point of the
capacity region.


title: Bounds on the mass-to-radius ratio for non-compact field configurations

abstract:
  It is well known that a spherically symmetric compact star whose energy
density decreases monotonically possesses an upper bound on its mass-to-radius
ratio, $2M/R\leq 8/9$. However, field configurations typically will not be
compact. Here we investigate non-compact static configurations whose matter
fields have a slow global spatial decay, bounded by a power law behavior. These
matter distributions have no sharp boundaries. We derive an upper bound on the
fundamental ratio max_r{2m(r)/r} which is valid throughout the bulk. In its
simplest form, the bound implies that in any region of spacetime in which the
radial pressure increases, or alternatively decreases not faster than some
power law $r^{-(c+4)}$, one has $2m(r)/r \leq (2+2c)/(3+2c)$. [For $c \leq 0$
the bound degenerates to $2m(r)/r \leq 2/3$.] In its general version, the bound
is expressed in terms of two physical parameters: the spatial decaying rate of
the matter fields, and the highest occurring ratio of the trace of the pressure
tensor to the local energy density.


title:
Magnetic phase transition and magnetocaloric effect in PrCo9Si4 and
  NdCo9Si4

abstract:
  The compounds, PrCo9Si4 and NdCo9Si4, have been recently reported to exhibit
first-order ferromagnetic transitions near 24 K. We have subjected this
compound for further characterization by magnetization, heat-capacity and
electrical resistivity measurements at low temperatures in the presence of
magnetic fields, particularly to probe magnetocaloric effect and
magnetoresistance. The compounds are found to exhibit rather modest
magnetocaloric effect at low temperatures peaking at Curie temperature,
tracking the behavior of magnetoresistance. The magnetic transition does not
appear to be first order in its character.


title:
Atom Interferometry with up to 24-Photon-Momentum-Transfer Beam
  Splitters

abstract:
  We present up to 24-photon Bragg diffraction as a beam splitter in
light-pulse atom interferometers to achieve the largest splitting in momentum
space so far. Relative to the 2-photon processes used in the most sensitive
present interferometers, these large momentum transfer beam splitters increase
the phase shift 12-fold for Mach-Zehnder (MZ-) and 144-fold for Ramsey-Borde
(RB-) geometries. We achieve a high visibility of the interference fringes (up
to 52% for MZ or 36% for RB) and long pulse separation times that are possible
only in atomic fountain setups. As the atom's internal state is not changed,
important systematic effects can cancel.


title: Baryon number violation and a new electroweak interaction

abstract:
  We introduce a new supercurrent in the electroweak sector of the standard
model. Its interaction with the hypergauge field influences the mass of the Z
boson but has no effect on the W^\pm-boson masses. In the leptonic sector it
affects the numerical value of the vector and axial coupling constants between
neutral currents and the Z boson, and a comparison with experimental values
yields an upper bound to the strength of the coupling between the supercurrent
and the hypergauge field. In the baryonic sector the supercurrent gives a new
contribution to the anomaly equation for baryon number current. As a
consequence it may have an effect on baryogenesis.


title:
Coalescing Cellular Automata -- Synchronizing CA by Common Random Source
  and Varying Asynchronicity

abstract:
  We say that a Cellular Automata (CA) is coalescing when its execution on two
distinct (random) initial configurations in the same asynchronous mode (the
same cells are updated in each configuration at each time step) makes both
configurations become identical after a reasonable time.
  We prove coalescence for two elementary rules, non coalescence for two other,
and show that there exists infinitely many coalescing CA. We then conduct an
experimental study on all elementary CA and show that some rules exhibit a
phase transition, which belongs to the universality class of directed
percolation.


title: Comment on "Hadronic $^3$He$\eta$ production near threshold"

abstract:
  Measurements of the differential and total cross sections for the $p d \to
  ^3$He $\eta$ reaction at five energies were recently reported [Phys. Rev. C
{\bf 75}, 014004 (2007)] and comparisons with theoretical models were made. We
point out that these comparisons involved a model based on ad hoc assumptions
and hence the conclusions regarding the reaction mechanism as well as the role
of the higher partial waves drawn in the above work are misleading. Revised
conclusions based on better model calculations are presented.


title: Knowledge Engineering Technique for Cluster Development

abstract:
  After the concept of industry cluster was tangibly applied in many countries,
SMEs trended to link to each other to maintain their competitiveness in the
market. The major key success factors of the cluster are knowledge sharing and
collaboration between partners. This knowledge is collected in form of tacit
and explicit knowledge from experts and institutions within the cluster. The
objective of this study is about enhancing the industry cluster with knowledge
management by using knowledge engineering which is one of the most important
method for managing knowledge. This work analyzed three well known knowledge
engineering methods, i.e. MOKA, SPEDE and CommonKADS, and compares the
capability to be implemented in the cluster context. Then, we selected one
method and proposed the adapted methodology. At the end of this paper, we
validated and demonstrated the proposed methodology with some primary result by
using case study of handicraft cluster in Thailand.


title: Helioseismic Ring Analysis of CME Source Regions

abstract:
  We apply the ring diagram technique to source regions of halo coronal mass
ejections (CMEs) to study changes in acoustic mode parameters before, during,
and after the onset of CMEs. We find that CME regions associated with a low
value of magnetic flux have line widths smaller than the quiet regions implying
a longer life-time for the oscillation modes. We suggest that this criterion
may be used to forecast the active regions which may trigger CMEs.


title:
A case study of the difficulty of quantifier elimination in constraint
  databases: the alibi query in moving object databases

abstract:
  In the constraint database model, spatial and spatio-temporal data are stored
by boolean combinations of polynomial equalities and inequalities over the real
numbers. The relational calculus augmented with polynomial constraints is the
standard first-order query language for constraint databases. Although the
expressive power of this query language has been studied extensively, the
difficulty of the efficient evaluation of queries, usually involving some form
of quantifier elimination, has received considerably less attention. The
inefficiency of existing quantifier-elimination software and the intrinsic
difficulty of quantifier elimination have proven to be a bottle-neck for for
real-world implementations of constraint database systems. In this paper, we
focus on a particular query, called the \emph{alibi query}, that asks whether
two moving objects whose positions are known at certain moments in time, could
have possibly met, given certain speed constraints. This query can be seen as a
constraint database query and its evaluation relies on the elimination of a
block of three existential quantifiers. Implementations of general purpose
elimination algorithms are in the specific case, for practical purposes, too
slow in answering the alibi query and fail completely in the parametric case.
The main contribution of this paper is an analytical solution to the parametric
alibi query, which can be used to answer this query in the specific case in
constant time. We also give an analytic solution to the alibi query at a fixed
moment in time. The solutions we propose are based on geometric argumentation
and they illustrate the fact that some practical problems require creative
solutions, where at least in theory, existing systems could provide a solution.


title: Outflows from Massive Stars

abstract:
  The properties of outflows powered by massive stars are reviewed with an
emphasis on the nearest examples, Orion and Cepheus-A. The Orion OMC1 outflow
may have been powered by the dynamical decay of a non-hierarchical massive star
system that resulted in the ejection of the BN object, and poossibly radio
soruces I and n from the OMC1 core. This interaction must have produced at
least one massive binary whose gravitational binding energy ejected the stars
and powered the outflow. A specific model for the coupling of this energy to
the gas is proposed. The radio source HW2 in the Cep-A region appears to drive
a pulsed, precessing jet that may be powered by a moderate-mass companion in an
eccentric and inclined orbit. This configuration may be the result of binary
formation by capture. These outflows demonstrate that dynamical interactions
among massive stars are an important feature of massive star formation.


title:
Mass Spectrum and Statistical Entropy of the BTZ black hole from
  Canonical Quantum Gravity

abstract:
  In a recent publication we developed a canonical quantization program
describing the gravitational collapse of a spherical dust cloud in 2+1
dimensions with a negative cosmological constant $-\Lambda\equiv -l^{-2}<0$. In
this paper we address the quantization of the Banados--Teitelboim--Zanelli
(BTZ) black hole. We show that the mass function describing the black hole is
made of two pieces, a constant non-vanishing boundary contribution and a
discrete spectrum of the form $\mu_n = \frac{\hbar}{l}(n+ \frac 12)$. The
discrete spectrum is obtained by applying the Wheeler--DeWitt equation with a
particular choice of factor ordering and interpreted as giving the energy
levels of the collapsed matter shells that form the black hole. Treating a
black hole microstate as a particular distribution of shells among the levels,
we determine the canonical entropy of the BTZ black hole. Comparison with the
Bekenstein--Hawking entropy shows that the boundary energy is related to the
central charge of the Virasoro algebra that generates the asymptotic symmetry
group of the three-dimensional anti-de Sitter space AdS$_3$. This gives a
connection between the Wheeler--DeWitt approach and the conformal field theory
approach.


title: Large magnetocaloric effect in Gd4Co3

abstract:
  We report a large entropy change (DeltaS) below 300 K, peaking near TC= 220
K, due to isothermal change of magnetic field, for Gd4Co3, with a refrigeration
capacity higher than that of Gd. Notably, the isothermal magnetization is
nonhysteretic - an important criterion for magnetic refrigeration without loss.
DeltaS behavior is also compared with that of magnetoresistance.


title: Continuum limits of random matrices and the Brownian carousel

abstract:
  We show that at any location away from the spectral edge, the eigenvalues of
the Gaussian unitary ensemble and its general beta siblings converge to
Sine_beta, a translation invariant point process. This process has a geometric
description in term of the Brownian carousel, a deterministic function of
Brownian motion in the hyperbolic plane.
  The Brownian carousel, a description of the a continuum limit of random
matrices, provides a convenient way to analyze the limiting point processes. We
show that the gap probability of Sine_beta is continuous in the gap size and
$\beta$, and compute its asymptotics for large gaps. Moreover, the stochastic
differential equation version of the Brownian carousel exhibits a phase
transition at beta=2.


title: Theoretical upper bound on the mass of the LSP in the MNSSM

abstract:
  We study the neutralino sector of the Minimal Non-minimal Supersymmetric
Standard Model (MNSSM) where the $\mu$ problem of the Minimal Supersymmetric
Standard Model (MSSM) is solved without accompanying problems related with the
appearance of domain walls. In the MNSSM as in the MSSM the lightest neutralino
can be the absolutely stable lightest supersymmetric particle (LSP) providing a
good candidate for the cold dark matter component of the Universe. In contrast
with the MSSM the allowed range of the mass of the lightest neutralino in the
MNSSM is limited. We establish the theoretical upper bound on the lightest
neutralino mass in the framework of this model and obtain an approximate
solution for this mass.


title: Magnetic anomalies in single crystalline ErPd2Si2

abstract:
  Considering certain interesting features in the previously reported 166Er
Moessbauer effect and neutron diffraction data on the polycrystalline form of
ErPd2Si2 crystallizing in ThCr2Si2-type tetragonal structure, we have carried
out magnetic measurements (1.8 to 300 K) on the single crystalline form of this
compound. We observe significant anisotropy in the absolute values of
magnetization (indicating that the easy axis is c-axis) as well as in the
features due to magnetic ordering in the plot of magnetic susceptibility (chi)
versus temperature (T) at low temperatures. The chi(T) data reveal that there
is a pseudo-low dimensional magnetic order setting in at 4.8 K, with a
three-dimensional antiferromagnetic ordering setting in at a lower temperature
(3.8 K). A new finding in the chi(T) data is that, for H//<110>, but not for
H//<001>, there is a broad shoulder in the range 8-20 K, indicative of the
existence of magnetic correlations above 5 K as well, which could be related to
the previously reported slow-relaxation-dominated Moessbauer spectra.
Interestingly, the temperature coefficient of electrical resistivity is found
to be isotropic; no feature due to magnetic ordering could be detected in the
electrical resistivity data at low temperatures, which is attributed to
magnetic Brillioun-zone boundary gap effects. The results reveal complex nature
of the magnetism of this compound.


title:
Spatial line nodes and fractional vortex pairs in the
  Fulde-Ferrell-Larkin-Ovchinnikov phase

abstract:
  A Zeeman magnetic field can induce a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)
phase in spin-singlet superconductors. Here we argue that there is a
non-trivial solution for the FFLO vortex phase that exists near the upper
critical field in which the wavefunction has only spatial line nodes that form
intricate and unusual three-dimensional structures. These structures include a
crisscrossing lattice of two sets of non-parallel line nodes. We show that
these solutions arise from the decay of conventional Abrikosov vortices into
pairs of fractional vortices. We propose that neutron scattering studies can
observe these fractional vortex pairs through the observation of a lattice of
1/2 flux quanta vortices. We also consider related phases in
non-centrosymmetric (NC) superconductors.


title: A Grand Challenge for Planetary Nebulae

abstract:
  The study of PN has been confronting a growing list of dilemmas which have
yet to find coherent resolution. These issues are both observational and
theoretical and can be stated as a series of "facts" which can not, as of yet,
be accounted for via a single framework. We review these facts and propose a
skeleton framework for developing a new understanding post-AGB stars, PPN and
PN. Our framework represents an attempt to articulate a a global perspective on
the late stages of stellar evolution that can embrace both the nature of the
central engine and the outflows they produce. Our framework focuses on
interacting binary central stars which drive collimated outflows through MHD
processes. We propose that the field of AGB/PN studies now faces a "Grand
Challenge" in articulating the observational systematics of these objects in a
way that can address issues related to binarity and magnetic shaping. A
theoretical Grand Challenge is also faced in the form of integrated studies
which can explicate the highly non-linear processes associated with MHD
outflows driven by interacting binaries. These issues include the generation of
magnetic fields via dynamo processes, the creation of accretion disks, the
dynamics of Common Envelope ejection and the creation of magnetized jets.


title:
Structure and Magnetic Fields in the Precessing Jet System SS 433 I.
  Multi-Frequency Imaging from 1998

abstract:
  The Very Large Array has been used at five frequencies to study the structure
and linear polarization of SS433 on scales as small as ~0.1" ~ 500 AU. Each jet
consists of a sharp, curving ridge-line at the leading edge, plus significant
trailing off-jet emission, showing that they are enveloped by diffuse
relativistic plasma. No kinematic model with constant jet speed fits our images
on all scales, but they are consistent with variations in jet speed of around
10% around the optical value. Our images show continuous jets with bright
components occurring simultaneously in the two jets roughly every 35 days. When
corrected for projection effects and Doppler boosting, the intensities of the
two jets are intrinsically very similar. Fractional linear polarization up to
20% is present along the ridge-lines, while the core is essentially
unpolarized. The rotation measures are consistent with a foreground screen with
RM ~ +110 radians per meter squared, plus a larger, asymmetrical contribution
close to the core. The apparent magnetic fields in the jets are roughly aligned
with the ridge-lines in most but not all of each jet. The jet is more highly
polarized between the components than in the components themselves, suggesting
that the mechanism that creates them compresses a tangled part of the magnetic
field into a partially-ordered transverse layer. The off-jet emission is
remarkably highly polarized, with m ~ 50% in places, suggesting large-scale
order of the magnetic field surrounding the jets. This polarized signal may
confuse the determination of magnetic field orientations in the jets
themselves. However, the images are consistent with a jet magnetic field that
is everywhere parallel to the helices.


title: On one uniqueness theorem for M. Rietz potentials

abstract:
  We prove that there exists a nonzero holderian real-to-real function
vanishing together with its M. Rietz potential in all points of some set of
positive length. This result improves the one of D. Beliaev and V. Havin. We
also extend the results to multidimensional M. Rietz potentials.


title: Stability of peakons for the Degasperis-Procesi equation

abstract:
  The Degasperis-Procesi equation can be derived as a member of a one-parameter
family of asymptotic shallow water approximations to the Euler equations with
the same asymptotic accuracy as that of the Camassa-Holm equation. In this
paper, we study the orbital stability problem of the peaked solitons to the
Degasperis-Procesi equation on the line. By constructing a Liapunov function,
we prove that the shapes of these peakon solitons are stable under small
perturbations.


title:
Effective Lagrangian approach to fermion electric dipole moments induced
  by a CP--violating $WW\gamma$ vertex

abstract:
  The one--loop contribution of the two CP--violating components of the
$WW\gamma$ vertex, $ \tilde{\kappa}_\gamma W^+_\mu W^-_\nu \tilde{F}^{\mu \nu}$
and $(\tilde{\lambda}_\gamma / m^2_W)W^+_{\mu \nu}W^{-\nu}_{\
\rho}\tilde{F}^{\rho \mu}$, on the electric dipole moment (EDM) of fermions is
calculated using dimensional regularization and its impact at low energies
reexamined in the light of the decoupling theorem. The Ward identities
satisfied by these couplings are derived by adopting a $SU_L(2)\times
U_Y(1)$--invariant approach and their implications in radiative corrections
discussed. Previous results on $\tilde{\kappa}_\gamma$, whose bound is updated
to $|\tilde{\kappa}_\gamma| <5.2\times 10^{-5}$, are reproduced, but
disagreement with those existing for $\tilde{\lambda}_\gamma$ is found. In
particular, the upper bound $|\tilde{\lambda}_\gamma|<1.9\times10^{-2}$ is
found from the limit on the neutron EDM, which is more than 2 orders of
magnitude less stringent than that of previous results. It is argued that this
difference between the $\tilde{\kappa}_\gamma$ and $\tilde{\lambda}_\gamma$
bounds is the one that might be expected in accordance with the decoupling
theorem. This argument is reinforced by analyzing careful the low--energy
behavior of the loop functions. The upper bounds on the $W$ EDM,
$|d_W|<6.2\times 10^{-21} e\cdot cm$, and the magnetic quadrupole moment,
$|\tilde{Q}_W|<3\times 10^{-36} e\cdot cm^2$, are derived. The EDM of the
second and third families of quarks and charged leptons are estimated. In
particular, EDM as large as $ 10^{-20} e\cdot cm$ and $10^{-21} e\cdot cm$ are
found for the $t$ and $b$ quarks, respectively.


title: Behavior of Ising Spin Glasses in a Magnetic Field

abstract:
  We study the existence of a spin-glass phase in a field using Monte Carlo
simulations performed along a nontrivial path in the field--temperature plane
that must cross any putative de Almeida-Thouless instability line. The method
is first tested on the Ising spin glass on a Bethe lattice where the
instability line separating the spin glass from the paramagnetic state is also
computed analytically. While the instability line is reproduced by our
simulations on the mean-field Bethe lattice, no such instability line can be
found numerically for the short-range three-dimensional model.


title: On the ODE/IM correspondence for minimal models

abstract:
  Within the framework of the ODE/IM correspondence, we show that the minimal
conformal field theories with c<1 emerge naturally from the monodromy
properties of certain families of ordinary differential equations.

categories: hep-th cond-mat.stat-mech math-ph math.MP math.QA quant-ph


title: Wigner Surmise For Domain Systems

abstract:
  In random matrix theory, the spacing distribution functions $p^{(n)}(s)$ are
well fitted by the Wigner surmise and its generalizations. In this
approximation the spacing functions are completely described by the behavior of
the exact functions in the limits s->0 and s->infinity. Most non equilibrium
systems do not have analytical solutions for the spacing distribution and
correlation functions. Because of that, we explore the possibility to use the
Wigner surmise approximation in these systems. We found that this approximation
provides a first approach to the statistical behavior of complex systems, in
particular we use it to find an analytical approximation to the nearest
neighbor distribution of the annihilation random walk.


title:
Low-temperature scanning tunneling microscopy of ring-like surface
  electronic structures around Co islands on InAs(110) surfaces

abstract:
  We report on the experimental observation by scanning tunneling microscopy at
low temperature of ring-like features that appear around Co metal clusters
deposited on a clean (110) oriented surface of cleaved p-type InAs crystals.
These features are visible in spectroscopic images within a certain range of
negative tunneling bias voltages due to the presence of a negative differential
conductance in the current-voltage dependence. A theoretical model is
introduced, which takes into account non-equilibrium effects in the small
tunneling junction area. In the framework of this model the appearance of the
ring-like features is explained in terms of interference effects between
electrons tunneling directly and indirectly (via a Co island) between the tip
and the InAs surface.


title:
Quantum and classical mode softening near the
  charge-density-wave/superconductor transition of Cu$_{x}$TiSe$_{2}$: Raman
  spectroscopic studies

abstract:
  Temperature- and x-dependent Raman scattering studies of the charge density
wave (CDW) amplitude modes in CuxTiSe2 show that the amplitude mode frequency
omega_o exhibits identical power-law scaling with the reduced temperature,
T/T_CDW, and the reduced Cu content, x/x_c, i.e., omega_o ~ (1 - p)^0.15 for p
= T/T_CDW or x/x_c, suggesting that mode softening is independent of the
control parameter used to approach the CDW transition. We provide evidence that
x-dependent mode softening in CuxTiSe2 is caused by the reduction of the
electron-phonon coupling constant lambda due to expansion of the lattice, and
that x-dependent `quantum' (T ~ 0) mode softening reveals a quantum critical
point within the superconductor phase of CuxTiSe2.


title:
Upper bound on the lightest neutralino mass in the Minimal Non--minimal
  Supersymmetric Standard Model

abstract:
  We consider the neutralino sector in the Minimal Non--minimal Supersymmetric
Standard Model (MNSSM). We argue that there exists a theoretical upper bound on
the lightest neutralino mass in the MNSSM. An approximate solution for the mass
of the lightest neutralino is obtained.


title:
A celestial gamma-ray foreground due to the albedo of small solar system
  bodies and a remote probe of the interstellar cosmic ray spectrum

abstract:
  We calculate the gamma-ray albedo flux from cosmic-ray (CR) interactions with
the solid rock and ice in Main Belt asteroids (MBAs), Jovian and Neptunian
Trojan asteroids, and Kuiper Belt objects (KBOs) using the Moon as a template.
We show that the gamma-ray albedo for the Main Belt, Trojans, and Kuiper Belt
strongly depends on the small-body size distribution of each system. Based on
an analysis of the Energetic Gamma Ray Experiment Telescope (EGRET) data we
infer that the diffuse emission from the MBAs, Trojans, and KBOs has an
integrated flux of less than ~6x10^{-6} cm^{-2} s^{-1} (100-500 MeV), which
corresponds to ~12 times the Lunar albedo, and may be detectable by the
forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected by GLAST,
it can provide unique direct information about the number of small bodies in
each system that is difficult to assess by any other method. Additionally, the
KBO albedo flux can be used to probe the spectrum of CR nuclei at
close-to-interstellar conditions. The orbits of MBAs, Trojans, and KBOs are
distributed near the ecliptic, which passes through the Galactic center and
high Galactic latitudes. Therefore, the asteroid gamma-ray albedo has to be
taken into account when analyzing weak gamma-ray sources close to the ecliptic,
especially near the Galactic center and for signals at high Galactic latitudes,
such as the extragalactic gamma-ray emission. The asteroid albedo spectrum also
exhibits a 511 keV line due to secondary positrons annihilating in the rock.
This may be an important and previously unrecognized celestial foreground for
the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of
the Galactic 511 keV line emission including the direction of the Galactic
center.


title: The Role of the Guide Field in Relativistic Pair Plasma Reconnection

abstract:
  We study the role of the guide field in relativistic magnetic reconnection in
a Harris current sheet of pair ($e^{\pm}$) plasmas, using linear theories and
particle-in-cell (PIC) simulations. Two-dimensional PIC simulations exhibit the
guide field dependence to the linear instabilities; the tearing or reconnection
modes are relatively insensitive, while the relativistic drift-kink instability
(RDKI), the fastest mode in a relativistic current sheet, is stabilized by the
guide field. Particle acceleration in the nonlinear stage is also investigated.
A three-dimensional PIC simulation demonstrates that the current sheet is
unstable to the RDKI, although small reconnection occurs in the deformed
current sheet. Another three-dimensional PIC simulation with a guide field
demonstrates a completely different scenario. Secondary magnetic reconnection
is triggered by nonlinear coupling of oblique instabilities, which we call the
relativistic drift-sausage tearing instability. Therefore, particle
acceleration by relativistic guide field reconnection occurs in
three-dimensional configuration. Based on the plasma theories, we discuss an
important role of the guide field: to enable non-thermal particle acceleration
by magnetic reconnection.


title:
The relation between stellar populations, structure and environment for
  dwarf elliptical galaxies from the MAGPOP-ITP

abstract:
  Dwarf galaxies, as the most numerous type of galaxy, offer the potential to
study galaxy formation and evolution in detail in the nearby Universe. Although
they seem to be simple systems at first view, they remain poorly understood. In
an attempt to alleviate this situation, the MAGPOP EU Research and Training
Network embarked on a study of dwarf galaxies named MAGPOP-ITP (Peletier et
al., 2007). In this paper, we present the analysis of a sample of 24 dwarf
elliptical galaxies (dEs) in the Virgo Cluster and in the field, using optical
long-slit spectroscopy. We examine their stellar populations in combination
with their light distribution and environment. We confirm and strengthen
previous results that dEs are, on average, younger and more metal-poor than
normal elliptical galaxies, and that their [alpha/Fe] abundance ratios scatter
around solar. This is in accordance with the downsizing picture of galaxy
formation where mass is the main driver for the star formation history. We also
find new correlations between the luminosity-weighted mean age, the large-scale
asymmetry, and the projected Virgocentric distance. We find that environment
plays an important role in the termination of the star formation activity by
ram pressure stripping of the gas in short timescales, and in the
transformation of disky dwarfs to more spheroidal objects by harassment over
longer timescales. This points towards a continuing infall scenario for the
evolution of dEs.


title: The matrix product representations for all valence bond states

abstract:
  We introduce a simple representation for irreducible spherical tensor
operators of the rotation group of arbitrary integer or half integer rank and
use these tensor operators to construct matrix product states corresponding to
all the variety of valence-bond states proposed in the
Affleck-Kennedy-Lieb-Tasaki (AKLT) construction. These include the fully
dimerized states of arbitrary spins, with uniform or alternating patterns of
spins, which are ground states of Hamiltonians with nearest and next-nearest
neighbor interactions, and the partially dimerized or AKLT/VBS (Valence Bond
Solid) states, which are constructed from them by projection. The latter states
are translation-invariant ground states of Hamiltonians with nearest-neighbor
interactions.


title:
Toward the zero surface tension limit: The granular fingering
  instability

abstract:
  The finger-like branching pattern that occurs when a less viscous fluid
displaces a more viscous one confined between two parallel plates has been
widely studied as a classical example of a mathematically-tractable
hydrodynamic instability since the time of Saffman and Taylor. Fingering in
such Hele-Shaw geometries have been generated not only with Newtonian fluids
but also with various non-Newtonian fluids including fine granular material
displaced by gas, liquid, or large grains. Here we study a granular Hele-Shaw
system to explore whether the absence of cohesive forces in dry granular
material can produce an ideal venue for studying the hitherto-unrealizable
singular hydrodynamics predicted in the zero-surface-tension limit. We
demonstrate that the grain-gas interface does indeed exhibit fractal structure
and sharp cusps associated with finite-time singularities. Above the yield
stress, the scaling for the finger width is distinct from that for ordinary
fluids, reflecting unique granular properties such as friction-induced
dissipation as opposed to viscous damping. Despite such differences, the
dimension of the global fractal structure and the shape of the singular cusps
on the interface agree with the theories based on simple Laplacian growth of
conventional fluid fingering in the zero-surface-tension limit. Our study
provides new insights not only on the dynamics of two-phase dense granular
flows and granular pattern formation, but also on the fluid dynamics in the
zero-surface-tension limit.


title: The Jiang-Su algebra does not always embed

abstract:
  We exhibit a unital simple nuclear non-type-I C*-algebra into which the
Jiang-Su algebra does not embed unitally. This answers a question of M.
R{\o}rdam.


title: Hypergeometric D-modules and twisted Gauss-Manin systems

abstract:
  The Euler-Koszul complex is the fundamental tool in the homological study of
A-hypergeometric differential systems and functions. We compare Euler-Koszul
homology with D-module direct images from the torus to the base space through
orbits in the corresponding toric variety. Our approach generalizes a result by
Gel'fand et al. and yields a simpler, more algebraic proof.
  In the process we extend the Euler-Koszul functor a category of infinite
toric modules and describe multigraded localizations of Euler-Koszul homology.


title: Constructing elliptic curves of prime order

abstract:
  We present a very efficient algorithm to construct an elliptic curve E and a
finite field F such that the order of the point group E(F) is a given prime
number N. Heuristically, this algorithm only takes polynomial time Otilde((\log
N)^3), and it is so fast that it may profitably be used to tackle the related
problem of finding elliptic curves with point groups of prime order of
prescribed size. We also discuss the impact of the use of high level modular
functions to reduce the run time by large constant factors and show that recent
gonality bounds for modular curves imply limits on the time reduction that can
be obtained.


title:
Far-reaching statistical consequences of the zero-point energy for the
  harmonic oscillator

abstract:
  In a recent thermodynamic analysis of the harmonic oscillator and using an
interpolation procedure, Boyer has shown that the existence of a zero-point
energy leads to the Planck spectrum. Here we avoid the interpolation by adding
a statistical argument to arrive at Planck's law as an inescapable result of
the presence of the zero-point energy. No explicit quantum argument is
introduced along the derivations. We disclose the connection of our results
with the original analysis of Planck and Einstein, which led to the notion of
the quantized radiation field. We then inquire into the discrete or continuous
behaviour of the energy and pinpoint the discontinuities. Finally, to open the
door to the description of the zero-point fluctuations, we briefly discuss the
statistical (in contrast to the purely thermodynamic) description of the
oscillator, which accounts for both thermal and temperature-independent
contributions to the energy dispersion.


title: Energy decay laws in strongly anisotropic MHD turbulence

abstract:
  We investigate the influence of a uniform magnetic field ${\bf B_0}=B_0 e//$
on energy decay laws in incompressible magnetohydrodynamic (MHD) turbulence.
The nonlinear transfer reduction along $B_0$ is included in a model that
distinguishes parallel and perpendicular directions, following a phenomenology
{\it \`a la} Kraichnan. We predict a slowing down of the energy decay due to
anisotropy in the limit of strong $B_0$, with distinct power laws for energy
decay of shear- and pseudo-Alfv\'en waves. Numerical results from the kinetic
equations of Alfv\'en wave turbulence recover these predictions, and MHD
numerical results clearly tend to follow them in the lowest perpendicular
planes.


title:
On the supergravity description of boost invariant conformal plasma at
  strong coupling

abstract:
  We study string theory duals of the expanding boost invariant conformal gauge
theory plasmas at strong coupling. The dual supergravity background is
constructed as an asymptotic late-time expansion, corresponding to
equilibration of the gauge theory plasma. The absence of curvature
singularities in the first few orders of the late-time expansion of the dual
gravitational background unambiguously determines the equilibrium equation of
the state, and the shear viscosity of the gauge theory plasma. While the
absence of the leading pole singularities in the gravitational curvature
invariants at the third order in late-time expansion determines the relaxation
time of the plasma, the subleading logarithmic singularity can not be canceled
within a supergravity approximation. Thus, a supergravity approximation to a
dual description of the strongly coupled boost invariant expanding plasma is
inconsistent. Nevertheless we find that the relaxation time determined from
cancellation of pole singularities is quite robust.


title: A graphene-based electrochemical switch

abstract:
  Conventional field effect transistor operation in graphene is limited by its
zero gap and minimum quantum conductivity. In this work, we report on
controlled electrochemical modification of graphene such that its conductance
changes by more than six orders of magnitude, which enables reversible bipolar
switching devices. The effect is explained by a chemical reaction of graphene
with hydrogen (H+) and hydroxyl (OH-), which are catalytically generated from
water molecules in the sub-stochiometric silicon oxide gate dielectric. The
reactive species attach to graphene making it nonconductive but the process can
subsequently be reversed by short current pulses that cause rapid local
annealing. We believe that the demonstrated electrochemical field effect
devices are viable candidates for future logic circuits, non-volatile memories
and novel neuromorphic processing concepts.


title:
Design and analytically full-wave validation of the invisibility cloaks,
  concentrators, and field rotators created with a general class of
  transformations

abstract:
  We investigate a general class of electromagnetic devices created with any
continuous transformation functions by rigorously calculating the analytical
expressions of the electromagnetic field in the whole space. Some interesting
phenomena associated with these transformation devices, including the
invisibility cloaks, concentrators, and field rotators, are discussed. By
carefully choosing the transformation function, we can realize cloaks which are
insensitive to perturbations at both the inner and outer boundaries.
Furthermore, we find that when the coating layer of the concentrator is
realized with left-handed materials, energy will circulate between the coating
and the core, and the energy transmits through the core of the concentrator can
be much bigger than that transmits through the concentrator. Therefore, such
concentrator is also a power flux amplifier. Finally, we propose a spherical
field rotator, which functions as not only a wave vector rotator, but also a
polarization rotator, depending on the orientations of the spherical rotator
with respect to the incident wave direction. The functionality of these novel
transformation devices are all successfully confirmed by our analytical full
wave method, which also provides an alternate computational efficient
validation method in contrast to numerical validation methods.


title:
Infinite coupling duals of N=2 gauge theories and new rank 1
  superconformal field theories

abstract:
  We show that a proposed duality [arXiv:0711.0054] between infinitely coupled
gauge theories and superconformal field theories (SCFTs) with weakly gauged
flavor groups predicts the existence of new rank 1 SCFTs. These superconformal
fixed point theories have the same Coulomb branch singularities as the rank 1
E_6, E_7, and E_8 SCFTs, but have smaller flavor symmetry algebras and
different central charges. Gauging various subalgebras of the flavor algebras
of these rank 1 SCFTs provides many examples of infinite-coupling dualities,
satisfying an intricate set of consistency checks. They also provide examples
of N=2 conformal theories with marginal couplings but no weak-coupling limits.