title: Hadron Spectrum in a Two-Colour Baryon-Rich Medium

abstract:
  The hadron spectrum of SU(2) lattice gauge theory with two flavours of Wilson
quark is studied on an 8^3x16 lattice using all-to-all propagators, with
particular emphasis on the dependence on quark chemical potential mu. As mu is
increased from zero the diquark states with non-zero baryon number B respond as
expected, while states with B=0 remain unaffected until the onset of non-zero
baryon density at mu=m_pi/2. Post onset the pi-meson mass increases in
accordance with chiral perturbation theory while the rho becomes lighter. In
the diquark sector a Goldstone state associated with a superfluid ground state
can be identified. A further consequence of superfluidity is an approximate
degeneracy between mesons and baryons with the same spacetime and isospin
quantum numbers. Finally we find tentative evidence for the binding of states
with kaon quantum numbers within the baryonic medium.


title:
Synchronization and bistability of qubit coupled to a driven dissipative
  oscillator

abstract:
  We study numerically the behavior of qubit coupled to a quantum dissipative
driven oscillator (resonator). Above a critical coupling strength the qubit
rotations become synchronized with the oscillator phase. In the synchronized
regime, at certain parameters, the qubit exhibits tunneling between two
orientations with a macroscopic change of number of photons in the resonator.
The life times in these metastable states can be enormously large. The
synchronization leads to a drastic change of qubit radiation spectrum with
appearance of narrow lines corresponding to recently observed single
artificial-atom lasing [O. Astafiev {\it et al.} Nature {\bf 449}, 588 (2007)].

categories: cond-mat.supr-con cond-mat.other nlin.CD quant-ph


title:
The Landau gauge gluon and ghost propagators in 4D SU(3) gluodynamics in
  large lattice volumes

abstract:
  We present recent results of the Landau gauge gluon and ghost propagators in
SU(3) pure gauge theory at Wilson \beta=5.7 for lattice sizes up to 80^4
corresponding to physical volumes up to (13.2 fm)^4. In particular, we focus on
finite-volume and Gribov copy effects. We employ a gauge fixing method that
combines a simulated annealing algorithm with finalizing overrelaxation. We
find the gluon propagator for the largest volumes and at q^2 ~ 0.01 GeV^2 to
become flat. Although not excluded by our data, there is still no clear
indication of a gluon propagator tending towards zero in the zero-momentum
limit. New data for the ghost propagator are reported, too.


title: Pfaffian Systems from Twistor Fibrations

abstract:
  Canonical twistor fibrations lead to Pfaffian systems by means of their
superhorizontal distribution. The aim of this note is to identify explicitly
the Pfaffian systems of five or less variables that arise in this way in terms
of the classification given by A.Awane and M.Goze.


title: Zeta functions of 3-dimensional p-adic Lie algebras

abstract:
  We give an explicit formula for the subalgebra zeta function of a general
3-dimensional Lie algebra over the p-adic integers $\mathbb{Z}_p$. To this end,
we associate to such a Lie algebra a ternary quadratic form over
$\mathbb{Z}_p$. The formula for the zeta function is given in terms of Igusa's
local zeta function associated to this form.


title:
Hydrogen on graphene: Electronic structure, total energy, structural
  distortions, and magnetism from first-principles calculations

abstract:
  Density functional calculations of electronic structure, total energy,
structural distortions, and magnetism for hydrogenated single-layer, bilayer,
and multi-layer graphene are performed. It is found that hydrogen-induced
magnetism can survives only at very low concentrations of hydrogen (single-atom
regime) whereas hydrogen pairs with optimized structure are usually
nonmagnetic. Chemisorption energy as a function of hydrogen concentration is
calculated, as well as energy barriers for hydrogen binding and release. The
results confirm that graphene can be perspective material for hydrogen storage.
Difference between hydrogenation of graphene, nanotubes, and bulk graphite is
discussed.


title:
Combinatorial Gelfand models for some semigroups and q-rook monoid
  algebras

abstract:
  Inspired by the results of [R. Adin, A. Postnikov, Y. Roichman, Combinatorial
Gelfand model, preprint math.RT arXiv:0709.3962], we propose combinatorial
Gelfand models for semigroup algebras of some finite semigroups, which include
the symmetric inverse semigroup, the dual symmetric inverse semigroup, the
maximal factorizable subsemigroup in the dual symmetric inverse semigroup, and
the factor power of the symmetric group. Furthermore we extend the Gelfand
model for the semigroup algebras of the symmetric inverse semigroup to a
Gelfand model for the $q$-rook monoid algebra.


title: The 0^{-+} and 0^{++} glueballs and the multiplets including them

abstract:
  The properties of the $0^{++}$ and $0^{-+}$ meson multiplets are discussed.
Quoted are the $0^{++}$ and $0^{-+}$ glueball masses determined from data fit.


title:
Microwave photovoltage and photoresistance effects in ferromagnetic
  microstrips

abstract:
  We investigate the dc electric response induced by ferromagnetic resonance in
ferromagnetic Permalloy (Ni80Fe20) microstrips. The resulting magnetization
precession alters the angle of the magnetization with respect to both dc and rf
current. Consequently the time averaged anisotropic magnetoresistance (AMR)
changes (photoresistance). At the same time the time-dependent AMR oscillation
rectifies a part of the rf current and induces a dc voltage (photovoltage). A
phenomenological approach to magnetoresistance is used to describe the distinct
characteristics of the photoresistance and photovoltage with a consistent
formalism, which is found in excellent agreement with experiments performed on
in-plane magnetized ferromagnetic microstrips. Application of the microwave
photovoltage effect for rf magnetic field sensing is discussed.


title:
The Levy-Gromov Isoperimetric Inequality in Convex Manifolds with
  Boundary

abstract:
  We observe after Bayle and Rosales that the Levy-Gromov isoperimetric
inequality generalizes to convex manifolds with boundary.


title: Solving Infinite Kolam in Knot Theory

abstract:
  In south India, there are traditional patterns of line-drawings encircling
dots, called ``Kolam'', among which one-line drawings or the ``infinite Kolam''
provide very interesting questions in mathematics. For example, we address the
following simple question: how many patterns of infinite Kolam can we draw for
a given grid pattern of dots? The simplest way is to draw possible patterns of
Kolam while judging if it is infinite Kolam. Such a search problem seems to be
NP complete. However, it is certainly not. In this paper, we focus on
diamond-shaped grid patterns of dots, (1-3-5-3-1) and (1-3-5-7-5-3-1) in
particular. By using the knot-theory description of the infinite Kolam, we show
how to find the solution, which inevitably gives a sketch of the proof for the
statement ``infinite Kolam is not NP complete.'' Its further discussion will be
given in the final section.


title:
Coulomb-Blocked Transport Through a Quantum Dot with Spin-Split Level:
  Increase of Differential Conductance Peaks by Spin Relaxation

abstract:
  Non-equilibrium transport through a quantum dot with one spin-split
single-particle level is studied in the cotunneling regime at low temperatures.
The Coulomb diamond can be subdivided into parts differing in at least one of
two respects: what kind of tunneling processes (i) determine the
single-particle occupations and (ii) mainly contribute to the current. No
finite systematic perturbation expansion of the occupations and the current can
be found that is valid within the entire Coulomb diamond. We therefore
construct a non-systematic solution, which is physically correct and
perturbative in the whole cotunneling regime, while smoothly crossing-over
between the different regions. With this solution the impact of an intrinsic
spin-flip relaxation on the transport is investigated. We focus on peaks in the
differential conductance that mark the onset of cotunneling-mediated sequential
transport. It is shown that these peaks are maximally pronounced at a
relaxation roughly as fast as sequential tunneling. The approach as well as the
presented results can be generalized to quantum dots with few levels.


title: The Role of Lepton Flavours in Thermal Leptogenesis

abstract:
  Thermal leptogenesis, that can be viewed as a consequence of the seesaw
model, is a very natural mechanism to explain the matter anti-matter asymmetry
of the Universe. Recently, lepton flavours have been included in the Boltzmann
equations, modifying significantly the evaluation of the efficiency of
leptogenesis to explain the observed baryon asymmetry.


title:
Groups with the Minimal Conditions for Subgroups and for Nonabelian
  Subgroups

abstract:
  For some very wide classes $\mathfrak{D}$ and
$\mathfrak{B}\subset\mathfrak{D}$ of groups, the author proves that an
arbitrary (nonabelian) group $G\in \mathfrak{D}$ (respectively $G\in
\mathfrak{B}$) satisfies the minimal condition for (nonabelian) subgroups iff
it is Chernikov


title:
The critical behavior of 3D Ising glass models: universality and scaling
  corrections

abstract:
  We perform high-statistics Monte Carlo simulations of three three-dimensional
Ising spin-glass models: the +-J Ising model for two values of the disorder
parameter p, p=1/2 and p=0.7, and the bond-diluted +-J model for
bond-occupation probability p_b = 0.45. A finite-size scaling analysis of the
quartic cumulants at the critical point shows conclusively that these models
belong to the same universality class and allows us to estimate the
scaling-correction exponent omega related to the leading irrelevant operator,
omega=1.0(1). We also determine the critical exponents nu and eta. Taking into
account the scaling corrections, we obtain nu=2.53(8) and eta=-0.384(9).


title: Oriented matroids and Ky Fan's theorem

abstract:
  L. Lovasz has shown that Sperner's combinatorial lemma admits a
generalization involving a matroid defined on the set of vertices of the
associated triangulation. Inspired by this result we prove that classical Ky
Fan's theorem admits an oriented matroid generalization of similar nature. Ky
Fan's theorem is obtained as a corollary if the underlying oriented matroid is
chosen to be the alternating matroid C^{m,r} .


title: Comparing SU(2) to SU(3) gluodynamics on large lattices

abstract:
  We study the SU(2) gluon and ghost propagators in Landau gauge on lattices up
to a size of 112^4. A comparison with the SU(3) case is made and finite-volume
effects are then investigated. We find that for a large range of momenta the
SU(2) and SU(3) propagators are remarkably alike. In the low-momentum region we
compare with recent results obtained in DSE studies on a 4-torus.


title: The quantum-classical crossover of a field mode

abstract:
  We explore the quantum-classical crossover in the behaviour of a quantum
field mode. The quantum behaviour of a two-state system - a qubit - coupled to
the field is used as a probe. Collapse and revival of the qubit inversion form
the signature for quantum behaviour of the field and continuous Rabi
oscillations form the signature for classical behaviour of the field. We
demonstrate both limits in a single model for the full coupled system, for
states with the same average field strength, and so for qubits with the same
Rabi frequency.


title:
Density modulations in an elongated Bose-Einstein condensate released
  from a disordered potential

abstract:
  We observe large density modulations in time-of-flight images of elongated
Bose-Einstein condensates, initially confined in a harmonic trap and in the
presence of weak disorder. The development of these modulations during the
time-of-flight and their dependence with the disorder are investigated. We
render an account of this effect using numerical and analytical calculations.
We conclude that the observed large density modulations originate from the weak
initial density modulations induced by the disorder, and not from initial phase
fluctuations (thermal or quantum).


title: Dynamics of Mandelbrot Cascades

abstract:
  Mandelbrot multiplicative cascades provide a construction of a dynamical
system on a set of probability measures defined by inequalities on moments. To
be more specific, beyond the first iteration, the trajectories take values in
the set of fixed points of smoothing transformations (i.e., some generalized
stable laws).
  Studying this system leads to a central limit theorem and to its functional
version. The limit Gaussian process can also be obtained as limit of an
`additive cascade' of independent normal variables.


title: A dual eigenvector condition for strong lumpability of Markov chains

abstract:
  Necessary and sufficient conditions for identifying strong lumpability in
Markov chains are presented. We show that the states in a lump necessarily
correspond to identical elements in eigenvectors of the dual transition matrix.
If there exist as many dual eigenvectors that respect the necessary condition
as there are lumps in the aggregation, then the condition is also sufficient.
The result is demonstrated with two simple examples.


title: Resonances in twisted quantum waveguides

abstract:
  In this paper we consider embedded eigenvalues of a Schroedinger Hamiltonian
in a waveguide induced by a symmetric perturbation. It is shown that these
eigenvalues become unstable and turn into resonances after twisting of the
waveguide. The perturbative expansion of the resonance width is calculated for
weakly twisted waveguides and the influence of the twist on resonances in a
concrete model is discussed in detail.


title: Deflated BiCGStab for linear equations in QCD problems

abstract:
  The large systems of complex linear equations that are generated in QCD
problems often have multiple right-hand sides (for multiple sources) and
multiple shifts (for multiple masses). Deflated GMRES methods have previously
been developed for solving multiple right-hand sides. Eigenvectors are
generated during solution of the first right-hand side and used to speed up
convergence for the other right-hand sides. Here we discuss deflating
non-restarted methods such as BiCGStab. For effective deflation, both left and
right eigenvectors are needed. Fortunately, with the Wilson matrix, left
eigenvectors can be derived from the right eigenvectors. We demonstrate for
difficult problems with kappa near kappa_c that deflating eigenvalues can
significantly improve BiCGStab. We also will look at improving solution of
twisted mass problems with multiple shifts. Projecting over previous solutions
is an easy way to reduce the work needed.


title:
Banach algebras of pseudodifferential operators and their almost
  diagonalization

abstract:
  We define new symbol classes for pseudodifferntial operators and investigate
their pseudodifferential calculus. The symbol classes are parametrized by
commutative convolution algebras. To every solid convolution algebra over a
lattice we associate a symbol class. Then every operator with such a symbol is
almost diagonal with respect to special wave packets (coherent states or Gabor
frames), and the rate of almost diagonalization is described precisely by the
underlying convolution algebra. Furthermore, the corresponding class of
pseudodifferential operators is a Banach algebra of bounded operators on $L^2
$. If a version of Wiener's lemma holds for the underlying convolution algebra,
then the algebra of pseudodifferential operators is closed under inversion. The
theory contains as a special case the fundamental results about Sj\"ostrand's
class and yields a new proof of a theorem of Beals about the H\"ormander class
of order 0.


title: Non-compact Gepner Models, Landau-Ginzburg Orbifolds and Mirror Symmetry

abstract:
  We study non-compact Gepner models that preserve sixteen or eight
supercharges in type II string theories. In particular, we develop an
orbifolded Landau-Ginzburg description of these models analogous to the
Landau-Ginzburg formulation of compact Gepner models. The Landau-Ginzburg
description provides an easy and direct access to the geometry of the
singularity associated to the non-compact Gepner models. Using these tools, we
are able to give an intuitive account of the chiral rings of the models, and of
the massless moduli in particular. By studying orbifolds of the singular linear
dilaton models, we describe mirror pairs of non-compact Gepner models by
suitably adapting the Greene-Plesser construction of mirror pairs for the
compact case. For particular models, we take a large level, low curvature limit
in which we can analyze corrections to a flat space orbifold approximation of
the non-compact Gepner models. This gives rise to a counting of moduli which
differs from the toric counting in a subtle way.


title:
Large spin expansion of the long-range Baxter equation in the sl(2)
  sector of N=4 SYM

abstract:
  Recently, several multi-loop conjectures have been proposed for the spin
dependence of anomalous dimensions of twist-2 and 3 operators in the sl(2)
sector of N=4 SYM. Currently, these conjectures are not proven, although
several consistency checks have been performed on their large spin expansion.
In this paper, we show how these expansions can be efficiently computed without
resorting to any conjecture. To this aim we present in full details a method to
expand at large spin the solution of the long-range Baxter equation. We treat
the twist-2 and 3 cases at two loops and the twist-3 case at three loops.
Several subtleties arise whose resolution leads to a simple algorithm computing
the expansion.


title: Self-consistent Mean Field theory in weakly ionized media

abstract:
  We present a self-consistent mean field theory of the dynamo in 3D and
turbulent diffusion in 2D in weakly ionized gas. We find that in 3D, the
backreaction does not alter the beta effect while it suppresses the alpha
effect when the strength of a mean magnetic field exceeds a critical value.
These results suggest that a mean field dynamo operates much more efficiently
in weakly ionized gas compared to the fully ionized gas. Furthermore, we show
that in 2D, the turbulent diffusion is suppressed by back reaction when a mean
magnetic field reaches the same critical strength, with the upper bound on
turbulent diffusion given by its kinematic value. Astrophysical implications
are discussed.


title: A turbulent model of torque in von Karman swirling flow

abstract:
  A stochastic model is derived to predict the turbulent torque produced by a
swirling flow. It is a simple Langevin process, with a colored noise. Using the
unified colored noise approximation, we derive analytically the PDF of the
fluctuations of injected power in two forcing regimes: constant angular
velocity or constant applied torque. In the limit of small velocity
fluctuations and vanishing inertia, we predict that the injected power
fluctuates twice less in the case of constant torque than in the case of
constant angular velocity forcing. The model is further tested against
experimental data in a von Karman device filled with water. It is shown to
allow for a parameter-free prediction of the PDF of power fluctuations in the
case where the forcing is made at constant torque. A physical interpretation of
our model is finally given, using a quasi-linear model of turbulence.


title: Metric Dichotomies

abstract:
  These are notes from talks given at ICMS, Edinburgh, 4/2007 ("Geometry and
Algorithms workshop") and at Bernoulli Center, Lausanne 5/2007 ("Limits of
graphs in group theory and computer science"). We survey the following type of
dichotomies exhibited by certain classes X of finite metric spaces: For every
host space H, either all metrics in X embed almost isometrically in H, or the
distortion of embedding some metrics of X in H is unbounded.


title: Influence of corruption on economic growth rate and foreign investments

abstract:
  In order to investigate whether government regulations against corruption can
affect the economic growth of a country, we analyze the dependence between
Gross Domestic Product (GDP) per capita growth rates and changes in the
Corruption Perceptions Index (CPI). For the period 1999-2004 on average for all
countries in the world, we find that an increase of CPI by one unit leads to an
increase of the annual GDP per capita by 1.7 %. By regressing only European
transition countries, we find that $\Delta$CPI = 1 generates increase of the
annual GDP per capita by 2.4 %. We also analyze the relation between foreign
direct investments received by different countries and CPI, and we find a
statistically significant power-law functional dependence between foreign
direct investment per capita and the country corruption level measured by the
CPI. We introduce a new measure to quantify the relative corruption between
countries based on their respective wealth as measured by GDP per capita.


title: Radius stabilization in 5D SUGRA models on orbifold

abstract:
  We study a four-dimensional effective theory of the five-dimensional (5D)
gauged supergravity with a universal hypermultiplet and perturbative
superpotential terms at the orbifold fixed points. The class of models we
consider includes the 5D heterotic M-theory and the supersymmetric
Randall-Sundrum model as special limits of the gauging parameters. We analyse
the vacuum structure of the models, especially the nature of the moduli
stabilization, from the viewpoint of the effective theory.


title:
Roles of Higgs decay into two pseudoscalar bosons in the search of
  intermediate-mass Higgs Boson

abstract:
  The dominance of $h\to \eta \eta$ decay mode for the intermediate mass Higgs
boson is highly motivated to solve the little hierarchy problem and to ease the
tension with the precision data. However, the discovery modes for $m_h \alt
150$ GeV, $h \to \gamma\gamma$ and $W/Z h \to (\ell\nu/\ell \bar \ell) (b\bar
b)$, will be substantially affected. We show that $h \to \eta \eta \to 4b$ is
complementary and we can use this decay mode to detect the intermediate Higgs
boson at the LHC, via $Wh$ and $Zh$ production. Requiring at least one charged
lepton and 4 $B$-tags in the final state, we can identify a clean Higgs boson
signal for $m_h \alt 150$ GeV with a high significance and with a full Higgs
mass reconstruction. We use the next-to-minimal supersymmetric standard model
and the simplest little Higgs model for illustration.


title: Entropy radiated by a braneworld black hole

abstract:
  The concept of black hole entropy is one of the most important enigmas of
theoretical physics. It relates thermodynamics to gravity and allows
substantial hints toward a quantum theory of gravitation. Although Bekenstein
conjecture -assuming the black hole entropy to be a measure of the number of
precollapse configurations- has proved to be extremely fruitful, a direct and
conclusive proof is still missing. This article computes accurately the entropy
evaporated by black holes in (4+n) dimensions taking into account the exact
greybody factors. This is a key process to constrain and understand the entropy
of black holes as the final state is unambiguously defined. Those results allow
to generalize Zurek's important argument, in favor of the Bekenstein
conjecture, to multi-dimensional scenarios.


title: Non Linear Gauge Fixing for FeynArts

abstract:
  We review the non-linear gauge-fixing for the Standard Model, proposed by F.
Boudjema and E. Chopin, and present our implementation of this non-linear
gauge-fixing to the Standard Model and to the minimal supersymmetric Standard
Model in FeynArts.


title:
Atomic Hydrogen Properties of AGN Host Galaxies: HI in 16 NUclei of
  GAlaxies (NUGA) Sources

abstract:
  We present a comprehensive spectroscopic imaging survey of the distribution
and kinematics of atomic hydrogen (HI) in 16 nearby spiral galaxies hosting low
luminosity AGN, observed with high spectral and spatial resolution (resolution:
~20 arcsec, 5 km/s) using the NRAO Very Large Array (VLA). The sample contains
a range of nuclear types, ranging from Seyfert to star-forming nuclei and was
originally selected for the NUclei of GAlaxies project (NUGA) - a spectrally
and spatially resolved interferometric survey of gas dynamics in nearby
galaxies designed to identify the fueling mechanisms of AGN and the relation to
host galaxy evolution. Here we investigate the relationship between the HI
properties of these galaxies, their environment, their stellar distribution and
their AGN type. The large-scale HI morphology of each galaxy is classified as
ringed, spiral, or centrally concentrated; comparison of the resulting
morphological classification with AGN type reveals that ring structures are
significantly more common in LINER than in Seyfert host galaxies, suggesting a
time evolution of the AGN activity together with the redistribution of the
neutral gas. Dynamically disturbed HI disks are also more prevalent in LINER
host galaxies than in Seyfert host galaxies. While several galaxies are
surrounded by companions (some with associated HI emission), there is no
correlation between the presence of companions and the AGN type
(Seyfert/LINER).


title:
Time evolution and decoherence of a spin-1/2 particle coupled to a spin
  bath in thermal equilibrium

abstract:
  The time evolution of a spin-1/2 particle under the influence of a locally
applied external magnetic field, and interacting with anisotropic spin
environment in thermal equilibrium at temperature $T$ is studied. The exact
analytical form of the reduced density matrix of the central spin is calculated
explicitly for finite number of bath spins. The case of an infinite number of
environmental spins is investigated using the convergence of the rescaled bath
operators to normal Gaussian random variables. In this limit, we derive the
analytical form of the components of the Bloch vector for antiferromagnetic
interactions within the bath, and we investigate the short-time and long-time
behavior of reduced dynamics. The effect of the external magnetic field, the
anisotropy and the temperature of the bath on the decoherence of the central
spin is discussed.


title:
Transverse-momentum, threshold and joint resummations for slepton pair
  production at hadron colliders

abstract:
  We present precision calculations of the transverse-momentum spectrum and the
invariant-mass distribution for slepton pair production at hadron colliders. We
implement the transverse-momentum, threshold and joint resummation formalisms
at the next-to-leading logarithmic accuracy and consistently match the obtained
result with the pure perturbative result at the first order in the strong
coupling constant, i.e. at order alpha_s. We give numerical predictions for
selectron and stau pair production, and compare the various resummed cross
sections with the perturbative result.


title: CMB Anisotropies and Inflation from Non-Standard Spinors

abstract:
  The apparent alignment of the cosmic microwave background multipoles on large
scales challenges the standard cosmological model. Scalar field inflation is
isotropic and cannot account for the observed alignment. We explore the
imprints, a non-standard spinor driven inflation would leave on the cosmic
microwave background anisotropies. We show it is natural to expect an
anisotropic inflationary expansion of the Universe which has the effect of
suppressing the low multipole amplitude of the primordial power spectrum, while
at the same time to provide the usual inflationary features.


title: Optimality of private quantum channels

abstract:
  We addressed the question of optimality of private quantum channels. We have
shown that the Shannon entropy of the classical key necessary to securely
transfer the quantum information is lower bounded by the entropy exchange of
the private quantum channel $\cal E$ and von Neumann entropy of the ciphertext
state $\varrho^{(0)}$. Based on these bounds we have shown that decomposition
of private quantum channels into orthogonal unitaries (if exists) is optimizing
the entropy. For non-ancillary single qubit PQC we have derived the optimal
entropy for arbitrary set of plaintexts. In particular, we have shown that
except when the (closure of the) set of plaintexts contains all states, one bit
key is sufficient. We characterized and analyzed all the possible single qubit
private quantum channels for arbitrary set of plaintexts. For the set of
plaintexts consisting of all qubit states we have characterized all possible
approximate private quantum channels and we have derived the relation between
the security parameter and the corresponding minimal entropy.


title: Hidden Fermion in Stueckelberg Z' Models as Milli-charged Dark Matter

abstract:
  The hidden Stueckelberg Z' model is augmented by a pair of Dirac fermions. If
the Z' has a coupling strength comparable to weak scale coupling, one can show
that this hidden fermion-antifermion pair could be a milli-charged dark matter
candidate with a viable relic density. Monochromatic photon flux coming from
the Galactic center due to pair annihilation of these milli-charged particles
is calculated and is shown to be within reach of the next generation gamma-ray
experiments. Characteristic collider signature of this theoretical endeavor is
that the Stueckelberg Z' boson has a large invisible width decaying into the
hidden fermion-antifermion pair if kinematically allowed. Singly production of
this Z' boson at the LHC and ILC are studied.


title:
Hyperflares of SGRs as an engine for millisecond extragalactic radio
  bursts

abstract:
  We propose that the strong millisecond extragalactic radio burst (mERB)
discovered by Lorimer et al. (2007) may be related to a hyperflare from an
extragalactic soft gamma-ray repeater. The expected rate of such hyperflares,
$\sim$ 20 - 100 d$^{-1}$ Gpc$^{-3}$, is in good correspondence with the value
estimated by Lorimer et al. The possible mechanism of radio emission can be
related to the tearing mode instability in the magnetar magnetosphere as
discussed by Lyutikov (2002), and can produce the radio flux corresponding to
the observed $\sim$ 30 Jy from the mERB using a simple scaling of the burst
energy.


title: The wave equation on singular space-times

abstract:
  We prove local unique solvability of the wave equation for a large class of
weakly singular, locally bounded space-time metrics in a suitable space of
generalised functions.


title: Statistical Relaxation in Closed Quantum Systems and the Van Hove-Limit

abstract:
  We analyze the dynamics of occupation probabilities for a certain type of
design models by the use of two different methods. On the one hand we present
some numerical calculations for two concrete interactions which point out that
the occurrence of statistical dynamics depends on the interaction structure.
Furthermore we show an analytical derivation for an infinite system that yields
statistical behaviour for the average over the whole ensemble of interactions
in the Van Hove-limit.


title: DBI Inflation using a One-Parameter Family of Throat Geometries

abstract:
  We demonstrate the possibility of examining cosmological signatures in the
DBI inflation setup using the BGMPZ solution, a one-parameter family of
geometries for the warped throat which interpolate between the Maldacena-Nunez
and Klebanov-Strassler solutions. The warp factor is determined numerically and
subsequently used to calculate cosmological observables including the scalar
and tensor spectral indices, for a sample point in the parameter space. As one
moves away from the KS solution for the throat the warp factor is qualitatively
different, which leads to a significant change for the observables, but also
generically increases the non-Gaussianity of the models. We argue that the
different models can potentially be differentiated by current and future
experiments.


title: NLO Event Simulation for Chargino Production at the ILC

abstract:
  We present an extension of the Monte Carlo Event Generator Whizard which
includes chargino production at the ILC at NLO. We include photons using both a
fixed order and a resummation approach. While the fixed order approach suffers
from negative event weights, the resummation method solves this problem and
automatically includes leading higher order corrections. We present results for
cross sections and event generation for both methods and evaluate the
systematic errors due to soft and collinear approximations. In the resummation
approach, the residual uncertainty can be brought down to the per-mil level.


title: The spatial string tension and dimensional reduction in QCD

abstract:
  The spatial string tension for 3+1 dimensional QCD at finite temperature is
measured. The gauge configurations we re generated with two light and one
heavier strange quark on lattices of size $16^3 4$ and $24^3 6$. This spatial
string tension is compared with the string tension of the 3 dimensional pure
gauge theory together with the temperature dependent 2-loop running coupling.
Further comparison is made with predictions from dimensionally reduced
effective theories.


title: Hamiltonian systems of hydrodynamic type in 2 + 1 dimensions

abstract:
  We investigate multi-dimensional Hamiltonian systems associated with constant
Poisson brackets of hydrodynamic type. A complete list of two- and
three-component integrable Hamiltonians is obtained. All our examples possess
dispersionless Lax pairs and an infinity of hydrodynamic reductions.


title:
Sub-leading contributions to the black hole entropy in the brick wall
  approach

abstract:
  [Abridged] We compute the canonical entropy of a quantum scalar field around
static and spherically symmetric black holes through the brick wall approach at
the higher orders (in fact, up to the sixth order in \hbar) in the WKB
approximation. We explicitly show that the brick wall model generally predicts
corrections to the Bekenstein-Hawking entropy in all spacetime dimensions. In
four dimensions, we find that the corrections to the Bekenstein-Hawking entropy
are of the form (A^n \log A), while, in six dimensions, the corrections behave
as (A^m + A^n \log A), where A denotes the area of the black hole event
horizon, and (m, n) < 1. We compare our results with the corrections to the
Bekenstein-Hawking entropy that have been obtained through the other approaches
in the literature, and discuss the implications.


title:
Quantum Effects for the Dirac Field in Reissner-Nordstrom-AdS Black Hole
  Background

abstract:
  The behavior of a charged massive Dirac field on a Reissner-Nordstrom-AdS
black hole background is investigated. The essential self-adjointness of the
Dirac Hamiltonian is studied. Then, an analysis of the discharge problem is
carried out in analogy with the standard Reissner-Nordstrom black hole case.


title:
Structure and f-dependence of the a.c.i.m. for a unimodal map f of
  Misiurewicz type

abstract:
  By using a suitable Banach space on which we let the transfer operator act,
we make a detailed study of the ergodic theory of a unimodal map $f$ of the
interval in the Misiurewicz case. We show in particular that the absolutely
continuous invariant measure $\rho$ can be written as the sum of 1/square root
spikes along the critical orbit, plus a continuous background. We conclude by a
discussion of the sense in which the map $f\mapsto\rho$ may be differentiable.


title: Decomposition of residue currents

abstract:
  Given a submodule $J\subset \mathcal O_0^{\oplus r}$ and a free resolution of
$J$ one can define a certain vector valued residue current whose annihilator is
$J$. We make a decomposition of the current with respect to Ass$(J)$ that
correspond to a primary decomposition of $J$. As a tool we introduce a class of
currents that includes usual residue and principal value currents; in
particular these currents admit a certain type of restriction to analytic
varieties and more generally to constructible sets.


title:
Discovery of very high energy gamma-ray emission in the W 28 (G6.4-0.1)
  region, and multiwavelength comparisons

abstract:
  H.E.S.S. observations of the old-age (>10^4yr; ~0.5deg diameter) composite
supernova remnant (SNR) W 28 reveal very high energy (VHE) gamma-ray emission
situated at its northeastern and southern boundaries. The northeastern VHE
source (HESS J1801-233) is in an area where W 28 is interacting with a dense
molecular cloud, containing OH masers, local radio and X-ray peaks. The
southern VHE sources (HESS J1800-240 with components labelled A, B and C) are
found in a region occupied by several HII regions, including the ultracompact
HII region W 28A2. Our analysis of NANTEN CO data reveals a dense molecular
cloud enveloping this southern region, and our reanalysis of EGRET data reveals
MeV/GeV emission centred on HESS J1801-233 and the northeastern interaction
region.


title: Cognitive Interference Channels with Confidential Messages

abstract:
  The cognitive interference channel with confidential messages is studied.
Similarly to the classical two-user interference channel, the cognitive
interference channel consists of two transmitters whose signals interfere at
the two receivers. It is assumed that there is a common message source (message
1) known to both transmitters, and an additional independent message source
(message 2) known only to the cognitive transmitter (transmitter 2). The
cognitive receiver (receiver 2) needs to decode both messages, while the
non-cognitive receiver (receiver 1) should decode only the common message.
Furthermore, message 2 is assumed to be a confidential message which needs to
be kept as secret as possible from receiver 1, which is viewed as an
eavesdropper with regard to message 2. The level of secrecy is measured by the
equivocation rate. A single-letter expression for the capacity-equivocation
region of the discrete memoryless cognitive interference channel is established
and is further explicitly derived for the Gaussian case. Moreover,
particularizing the capacity-equivocation region to the case without a secrecy
constraint, establishes a new capacity theorem for a class of interference
channels, by providing a converse theorem.


title: MagnetoResistance of graphene-based spin valves

abstract:
  We study the magnetoresistance of spin-valve devices using graphene as a
non-magnetic material to connect ferromagnetic leads. As a preliminary step we
first study the conductivity of a graphene strip connected to metallic contacts
for a variety of lead parameters, and demonstrate that the resulting
conductivity is rather insensitive to them. We then compute the conductivity of
the spin-valve device in the parallel and antiparallel spin polarization
configurations, and find that it depends only weakly on the relative spin
orientations of the leads, so that the magnetoresistance $MR$ of the system is
very small. The smallness of $MR$ is a consequence of the near independence of
the graphene conductivity from the electronic details of the leads. Our results
indicate that, although graphene has properties that make it attractive for
spintronic devices, the performance of an graphene-based spin-valve is likely
to be poor.


title: Valiron's construction in higher dimension

abstract:
  We consider holomorphic self-maps $\v$ of the unit ball $\B^N$ in $\C^N$
($N=1,2,3,...$). In the one-dimensional case, when $\v$ has no fixed points in
$\D\defeq \B^1$ and is of hyperbolic type, there is a classical renormalization
procedure due to Valiron which allows to semi-linearize the map $\phi$, and
therefore, in this case, the dynamical properties of $\phi$ are well
understood. In what follows, we generalize the classical Valiron construction
to higher dimensions under some weak assumptions on $\v$ at its Denjoy-Wolff
point. As a result, we construct a semi-conjugation $\sigma$, which maps the
ball into the right half plane of $\C$, and solves the functional equation
$\sigma\circ \v=\lambda \sigma$, where $\lambda>1$ is the (inverse of the)
boundary dilation coefficient at the Denjoy-Wolff point of $\v$.


title: Non-linear QCD

abstract:
  In this talk I give the mini-review on recent development in the non-linear
QCD (at low $x$).


title:
Short distance modifications to Newton's law in SUSY braneworld
  scenarios

abstract:
  In braneworld models coming from string theory one generally encounters
massless scalar degrees of freedom -moduli- parameterizing the volume of small
compact extra-dimensions. Here we discuss the effects of such moduli on
Newton's law for a fairly general 5-D supersymmetric braneworld scenario with a
bulk scalar field $\phi$. We show that the Newtonian potential describing the
gravitational interaction between two bodies localized on the visible brane
picks up a non-trivial contribution at short distances that depends on the
shape of the superpotential $W(\phi)$ of the theory. In particular, we compute
this contribution for dilatonic braneworld scenarios $W(\phi) = e^{\alpha
\phi}$ (where $\alpha$ is a constant) and discuss the particular case of 5-D
Heterotic M-theory.


title: Model of World; her cities, languages and countries

abstract:
  The time evolution of Earth with her cities, languages and countries is
considered in terms of the multiplicative noise and the fragmentation-
processes, where the related families, size distributions, lifetimes,
bilinguals, etc. are studied. Earlier we treated the cities and the languages
differently (and as connected; languages split since cities split, etc.).
Hence, two dis- tributions are obtained in the same computation at the same
time. The same approach is followed here and Pareto-Zipf law for the
distribution of the cities, log-normal for the languages, decreasing
exponential for the city families (countries) in the rank order over
population, and power law -2 for the language families over the number of
languages in rank order are obtained theoretically in this combination for the
first time (up to our knowledge) in the literature; all of which are in good
agreement with the present empirical data.


title: Ratios: A short guide to confidence limits and proper use

abstract:
  Researchers often calculate ratios of measured quantities. Specifying
confidence limits for ratios is difficult and the appropriate methods are often
unknown. Appropriate methods are described (Fieller, Taylor, special bootstrap
methods). For the Fieller method a simple geometrical interpretation is given.
Monte Carlo simulations show when these methods are appropriate and that the
most frequently used methods (index method and zero-variance method) can lead
to large liberal deviations from the desired confidence level. It is discussed
when we can use standard regression or measurement error models and when we
have to resort to specific models for heteroscedastic data. Finally, an old
warning is repeated that we should be aware of the problems of spurious
correlations if we use ratios.


title:
Mechanisms of exchange bias with multiferroic BiFeO3 epitaxial thin
  films

abstract:
  We have combined neutron scattering and piezoresponse force microscopy to
study the relation between the exchange bias observed in CoFeB/BiFeO3
heterostructures and the multiferroic domain structure of the BiFeO3 films. We
show that the exchange field scales with the inverse of the ferroelectric and
antiferromagnetic domain size, as expected from Malozemoff's model of exchange
bias extended to multiferroics. Accordingly, polarized neutron reflectometry
reveals the presence of uncompensated spins in the BiFeO3 film at the interface
with the CoFeB. In view of these results we discuss possible strategies to
switch the magnetization of a ferromagnet by an electric field using BiFeO3.


title:
Concerning the Strauss conjecture and almost global existence for
  nonlinear Dirichlet-wave equations in 4-dimensions

abstract:
  We show the obstacle version of the Strauss conjecture holds when the spatial
dimension is equal to 4. We also show that an almost global existence theorem
of H\"ormander for (4+1)-dimensional Minkowski space holds in the obstacle
setting. We use weighed space-time variants of the energy inequality and a
variant of the classical Hardy inequality.


title: TenTen: A New Array of Multi-TeV Imaging Cherenkov Telescopes

abstract:
  The exciting results from H.E.S.S. point to a new population of gamma-ray
sources at energies E > 10 TeV, paving the way for future studies and new
discoveries in the multi-TeV energy range. Connected with these energies is the
search for sources of PeV cosmic-rays (CRs) and the study of multi-TeV
gamma-ray production in a growing number of astrophysical environments. TenTen
is a proposed stereoscopic array (with a suggested site in Australia) of
modest-sized (10 to 30m^2) Cherenkov imaging telescopes with a wide field of
view (8 to 10deg diameter) optimised for the E~10 to 100 TeV range. TenTen will
achieve an effective area of ~10 km^2 at energies above 10 TeV. We outline here
the motivation for TenTen and summarise key performance parameters.


title:
Higher string functions, higher-level Appell functions, and the
  logarithmic ^sl(2)_k/u(1) CFT model

abstract:
  We generalize the string functions C_{n,r}(tau) associated with the coset
^sl(2)_k/u(1) to higher string functions A_{n,r}(tau) and B_{n,r}(tau)
associated with the coset W(k)/u(1) of the W-algebra of the logarithmically
extended ^sl(2)_k conformal field model with positive integer k. The higher
string functions occur in decomposing W(k) characters with respect to level-k
theta and Appell functions and their derivatives (the characters are neither
quasiperiodic nor holomorphic, and therefore cannot decompose with respect to
only theta-functions). The decomposition coefficients, to be considered
``logarithmic parafermionic characters,'' are given by A_{n,r}(tau),
B_{n,r}(tau), C_{n,r}(tau), and by the triplet \mathscr{W}(p)-algebra
characters of the (p=k+2,1) logarithmic model. We study the properties of
A_{n,r} and B_{n,r}, which nontrivially generalize those of the classic string
functions C_{n,r}, and evaluate the modular group representation generated from
A_{n,r}(tau) and B_{n,r}(tau); its structure inherits some features of modular
transformations of the higher-level Appell functions and the associated
transcendental function Phi.


title: Volume Weighting in the No Boundary Proposal

abstract:
  It has been suggested that the no boundary proposal would predict little or
no slow roll inflation leading to an empty deSitter universe. However it is
argued that the probability for the whole universe should be multiplied by a
zero mode factor $e^{3N}$ which counts the number of Hubble volumes in the
universe. This volume weighting is similar to that in eternal inflation but
derived in a gauge invariant manner. It predicts that inflation began at a
saddle point in the potential and that the universe was always in the
semi-classical regime.


title: FSR0190 - Another old distant galactic cluster

abstract:
  We are conducting a large program to classify newly discovered Milky Way star
cluster candidates from Froebrich et al. (2007). Here we present NIR follow-up
observations of FSR0190 (RA=20h05m31.3s, DEC=33deg34'09" J2000). The cluster is
situated close to the Galactic Plane (l=70.7302deg, b=+0.9498deg). It shows a
circular shape, a relatively large number of core helium burning stars -- which
clearly distinguishes the cluster from the rich field -- but no centrally
condensed star density profile. We derive an age of more than 7Gyr, a
Galactocentric distance of 10.5kpc, a distance of 10kpc from the Sun, and an
extinction of A_K=0.8mag. The estimated mass is at least of the order of
1E5M_sun, and the absolute brightness is M_V<=-4.7mag; both are rather typical
properties for Palomar-type globular clusters.


title:
Modeling a Schottky-barrier carbon nanotube field-effect transistor with
  ferromagnetic contacts

abstract:
  In this study, a model of a Schottky-barrier carbon nanotube field- effect
transistor (CNT-FET), with ferromagnetic contacts, has been developed. The
emphasis is put on analysis of current-voltage characteristics as well as shot
(and thermal) noise. The method is based on the tight-binding model and the
non- equilibrium Green's function technique. The calculations show that, at
room temperature, the shot noise of the CNT FET is Poissonian in the
sub-threshold region, whereas in elevated gate and drain/source voltage regions
the Fano factor gets strongly reduced. Moreover, transport properties strongly
depend on relative magnetization orientations in the source and drain contacts.
In particular, one observes quite a large tunnel magnetoresistance, whose
absolute value may exceed 50%.


title:
Construction of a Penrose Diagram for a Spatially Coherent Evaporating
  Black Hole

abstract:
  A Penrose diagram is constructed for an example black hole that evaporates at
a steady rate as measured by a distant observer, until the mass vanishes,
yielding a final state Minkowski space-time. Coordinate dependencies of
significant features, such as the horizon and coordinate anomalies, are clearly
demonstrated on the diagram. The large-scale causal structure of the space-time
is briefly discussed.


title: Ricci curvature and conformality of Riemannian manifolds to spheres

abstract:
  In this paper we give bounds for the first eigenvalue of the conformal
Laplacian and the Yamabe invariant of a compact Riemannian manifold, by using
conditions on the Ricci curvature and the diameter and deduce certain
conditions on the manifold to be conformal to a sphere.


title: R-Parity violating minimal supergravity at the LHC

abstract:
  We consider the case where supersymmetry with broken R-parity is embedded in
the minimal supergravity model (mSUGRA). This alters the standard mSUGRA
spectrum and opens a wide range in parameter space, where the scalar tau is the
lightest supersymmetric particle, instead of the lightest neutralino. We study
the resulting LHC phenomenology. Promising signatures would be detached
vertices from long-lived staus, multi lepton final states and multi-tau final
states. We investigate in detail the corresponding cross sections and decay
rates in characteristic benchmark scenarios.


title: Electroweak Contributions to Squark Pair Production

abstract:
  We compute electroweak contributions to the production of squark pairs at
hadron colliders. These include the exchange of electroweak gauge bosons in the
$s-$channel as well as electroweak gaugino exchange in the $t-$ and/or
$u-$channel. In many cases these can interfere with the dominant QCD
contributions. As a result, we find sizable contributions to the production of
two SU(2) doublet squarks. At the LHC, they amount to 10 to 20% for typical
mSUGRA (or CMSSM) scenarios, but in more general scenarios they can vary
between -40 and $+55%$, depending on size and sign of the SU(2) gaugino mass.
The electroweak contribution to the total squark pair production rate at the
LHC is about 3.5 times smaller.


title:
Cutoff effects for Wilson twisted mass fermions at tree-level of
  perturbation theory

abstract:
  We study cutoff effects at tree-level of perturbation theory for standard
Wilson and Wilson twisted mass fermionic lattice actions with Nf=2 flavour
degenerate quarks. The discretization effects are investigated by computing the
mass spectrum and decay amplitudes for different hadron interpolating fields
and the scaling behaviour towards the continuum limit is analyzed. It is shown
that the Wilson and the mass average methods are equivalent and lead to O(a)
improved R5-parity even lattice observables. We also demonstrate that automatic
O(a) improvement works in case of Wilson twisted mass fermions at maximal twist
and that this improvement is realized even if the condition of maximal twist is
achieved only up to O(a) cutoff effects. We demonstrate that in the chiral
limit standard Wilson fermions show scaling violations of O(a^2) while for
maximally twisted mass fermions these violations are only of O(a^4). For our
analytical calculations, lattices with sizes L=aN and periodic boundary
conditions in the spatial directions have been chosen while infinite extension
in the time direction is considered.


title:
An Affinity Propagation Based method for Vector Quantization Codebook
  Design

abstract:
  In this paper, we firstly modify a parameter in affinity propagation (AP) to
improve its convergence ability, and then, we apply it to vector quantization
(VQ) codebook design problem. In order to improve the quality of the resulted
codebook, we combine the improved AP (IAP) with the conventional LBG algorithm
to generate an effective algorithm call IAP-LBG. According to the experimental
results, the proposed method not only enhances the convergence abilities but
also is capable of providing higher-quality codebooks than conventional LBG
method.


title: The Minimal Flavor Violating MSSM: application to meson mixings

abstract:
  We provide a short account of the effects one expects on meson-antimeson
oscillations in the context of the Minimal Supersymmetric Standard Model
(MSSM). This issue is largely dependent on the assumptions made on the MSSM
parameter space. In this respect, we consider in closer detail the cases of the
general MSSM, with completely free soft terms, and the Minimal Flavor Violating
limit of the MSSM, providing a natural mechanism of near-flavor-conservation.
For the case of meson oscillations in the Delta B = 2 sector, we show that this
approach leads to a striking increase of the predictivity of the model. In
particular, we find (i) SUSY corrections to be naturally small and always
positive; (ii) if mu is not small, an increase in importance (even for low tan
beta) of scalar operators due to gluino contributions. The last point signals
that (V-A)x(V-A) dominated MFV is in general inconsistent with the MSSM. In
this context, we also briefly discuss the MFV-Unitarity Triangle.


title: A method of moments estimator of tail dependence

abstract:
  In the world of multivariate extremes, estimation of the dependence structure
still presents a challenge and an interesting problem. A procedure for the
bivariate case is presented that opens the road to a similar way of handling
the problem in a truly multivariate setting. We consider a semi-parametric
model in which the stable tail dependence function is parametrically modeled.
Given a random sample from a bivariate distribution function, the problem is to
estimate the unknown parameter. A method of moments estimator is proposed where
a certain integral of a nonparametric, rank-based estimator of the stable tail
dependence function is matched with the corresponding parametric version. Under
very weak conditions, the estimator is shown to be consistent and
asymptotically normal. Moreover, a comparison between the parametric and
nonparametric estimators leads to a goodness-of-fit test for the semiparametric
model. The performance of the estimator is illustrated for a discrete spectral
measure that arises in a factor-type model and for which likelihood-based
methods break down. A second example is that of a family of stable tail
dependence functions of certain meta-elliptical distributions.


title: $B \to K^* \ell^+ \ell^-$ as a probe of Universal Extra Dimensions

abstract:
  We study some rare B decays induced by $b \to s$ transition within the
Standard Model and in the Appelquist-Cheng-Dobrescu model, which is a New
Physics scenario with a single universal extra dimension. In particular, we
discuss the dependence on the radius $R$ of the compactified extra-dimension of
the branching ratio, the forward-backward asymmetry and the $K^*$ helicity
distributions for the decay modes $B \to K^* \ell^+ \ell^-$, with
$\ell^-=e^-,\mu^-$, and the tau polarization asymmetries for the mode $B \to
K^* \tau^+ \tau^-$.


title:
Thin-shell wormholes supported by ordinary matter in
  Einstein--Gauss--Bonnet gravity

abstract:
  The generalized Darmois--Israel formalism for Einstein--Gauss--Bonnet theory
is applied to construct thin-shell Lorentzian wormholes with spherical
symmetry. We calculate the energy localized on the shell, and we find that for
certain values of the parameters wormholes could be supported by matter not
violating the energy conditions.


title: Gravitomagnetism in superconductors and compact stars

abstract:
  There are three experimentally observed effects in rotating superconductors
that are so far unexplained. Some authors have tried to interpret such a
phenomena as possible new gravitational properties of coherent quantum systems:
in particular, they suggest that the gravitomagnetic field of that kind of
matter may be many orders of magnitude stronger than the one expected in the
standard theory. Here I show that this interpretation would be in conflict with
the common belief that neutron stars have neutrons in superfluid state and
protons in superconductive one.


title: Roots, symmetries and conjugacy of pseudo-Anosov mapping classes

abstract:
  An algorithm is proposed that solves two decision problems for pseudo-Anosov
elements in the mapping class group of a surface with at least one marked fixed
point. The first problem is the root problem: decide if the element is a power
and in this case compute the roots. The second problem is the symmetry problem:
decide if the element commutes with a finite order element and in this case
compute this element. The structure theorem on which this algorithm is based
provides also a new solution to the conjugacy problem.


title: Estimation of Gaussian graphs by model selection

abstract:
  We investigate in this paper the estimation of Gaussian graphs by model
selection from a non-asymptotic point of view. We start from a n-sample of a
Gaussian law P_C in R^p and focus on the disadvantageous case where n is
smaller than p. To estimate the graph of conditional dependences of P_C, we
introduce a collection of candidate graphs and then select one of them by
minimizing a penalized empirical risk. Our main result assess the performance
of the procedure in a non-asymptotic setting. We pay a special attention to the
maximal degree D of the graphs that we can handle, which turns to be roughly
n/(2 log p).


title: Purity distribution for bipartite random pure states

abstract:
  Analytic expressions for the probability density distribution of the linear
entropy and the purity are derived for bipartite pure random quantum states.
The explicit distributions for a state belonging to a product of Hilbert spaces
of dimensions p and q are given for p=3 and any q>=3, as well as for p=q=4.


title: Quark model: recent issues

abstract:
  In the first part I briefly survey recent issues in constituent quark models
raised by the observation of unusual hadronic states. In particular I discuss
the role of higher Fock components in the wave function of baryons and the
possible interpretation of open charm and of new charmonium-type resonances as
tetraquarks. In the second part I show support for the quark model dynamics
obtained in a model independent way from the $1/N_c$ expansion approach of QCD
which proved to be successful in describing baryon properties.


title: Theory of cooling neutron stars versus observations

abstract:
  We review current state of neutron star cooling theory and discuss the
prospects to constrain the equation of state, neutrino emission and superfluid
properties of neutron star cores by comparing the cooling theory with
observations of thermal radiation from isolated neutron stars.


title:
Longitudinal double-spin asymmetry for inclusive jet production in p+p
  collisions at sqrt(s)=200 GeV

abstract:
  We report a new STAR measurement of the longitudinal double-spin asymmetry
A_LL for inclusive jet production at mid-rapidity in polarized p+p collisions
at a center-of-mass energy of sqrt(s) = 200 GeV. The data, which cover jet
transverse momenta 5 < p_T < 30 GeV/c, are substantially more precise than
previous measurements. They provide significant new constraints on the gluon
spin contribution to the nucleon spin through the comparison to predictions
derived from one global fit of polarized deep-inelastic scattering
measurements.


title: The volume and Chern-Simons invariant of a representation

abstract:
  We give an efficient simplicial formula for the volume and Chern-Simons
invariant of a boundary-parabolic PSL(2,C)-representation of a tame 3-manifold.
If the representation is the geometric representation of a hyperbolic
3-manifold, our formula computes the volume and Chern-Simons invariant directly
from an ideal triangulation with no use of additional combinatorial topology.
In particular, the Chern-Simons invariant is computed just as easily as the
volume.


title:
The control of iron oxidation state during FeO and olivine crystal
  growth

abstract:
  Crystal growth experiments (micro-pulling down or Czochralski methods,
respectively) and DTA/TG measurements with Fe2+ containing olivines
(fayalite--forsterite solid solution) and with FeO (wustite) are performed. For
both substances the oxygen partial pressure p_O2 of the growth atmosphere had
to be adjusted within the stability region of Fe2+ for all temperatures ranging
from room temperature to the melting point. The formation of Fe3+ (Fe3O4,
Fe2O3) had to be avoided. The adjustment of p_O2 could be obtained by a mixture
of argon, carbon dioxide and carbon monoxide. Thermodynamic equilibrium
calculations show, that mixtures of an inert gas (e.g. argon) with another gas
or gas mixture that supplies oxygen at elevated temperature (e.g. CO2/CO) are
superior to the use of inert gases with constant oxygen admixture. The reason
is that the Ar/CO2/CO mixture adjusts its oxygen concentration with temperature
in a way similar to that needed for the stabilization of Fe2+.


title: Lecture Notes on Quantum Teichmuller Theory

abstract:
  These notes are based on a lecture course by L. Chekhov held at the
University of Manchester in May 2006 and February-March 2007. They are
divulgative in character, and instead of containing rigorous mathematical
proofs, they illustrate statements giving an intuitive insight. We
intentionally remove most bibliographic references from the body of the text
devoting a special section to the history of the subject at the end.


title: Boltzmann, Gibbs and the Concept of Equilibrium

abstract:
  The Boltzmann and Gibbs approaches to statistical mechanics have very
different definitions of equilibrium and entropy. The problems associated with
this are discussed and it is suggested that they can be resolved, to produce a
version of statistical mechanics incorporating both approaches, by redefining
equilibrium not as a binary property (being/not being in equilibrium) but as a
continuous property (degrees of equilibrium) measured by the Boltzmann entropy
and by introducing the idea of thermodynamic-like behaviour for the Boltzmann
entropy. The Kac ring model is used as an example to test the proposals.


title: Fokker-Planck Equation for Fractional Systems

abstract:
  The normalization condition, average values and reduced distribution
functions can be generalized by fractional integrals. The interpretation of the
fractional analog of phase space as a space with noninteger dimension is
discussed. A fractional (power) system is described by the fractional powers of
coordinates and momenta. These systems can be considered as non-Hamiltonian
systems in the usual phase space. The generalizations of the Bogoliubov
equations are derived from the Liouville equation for fractional (power)
systems. Using these equations, the corresponding Fokker-Planck equation is
obtained.


title:
Non-gapped Fermi surfaces, quasiparticles and the anomalous temperature
  dependence of the near-$E_F$ electronic states in the CMR oxide
  La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ with $x=0.36$

abstract:
  After years of research into colossal magnetoresistant (CMR) manganites using
bulk techniques, there has been a recent upsurge in experiments directly
probing the electronic states at or near the surface of the bilayer CMR
materials La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ using angle-resolved photoemission
or scanning probe microscopy. Here we report new, temperature dependent, angle
resolved photoemission data from single crystals with a doping level of
$x=0.36$. The first important result is that there is no sign of a pseudogap in
the charge channel of this material for temperatures below the Curie
temperature $T_C$. The second important result concerns the temperature
dependence of the electronic states. The temperature dependent changes in the
Fermi surface spectra both at the zone face and zone diagonal regions in
$k$-space indicate that the coherent quasiparticle weight disappears for
temperatures significantly above $T_C$, and that the $k$-dependence of the
T-induced changes in the spectra invalidate an interpretation of these data in
terms of the superposition of a `universal' metallic spectrum and an insulating
spectrum whose relative weight changes with temperature. In this sense, our
data are not compatible with a phase separation scenario.


title: Anatomy of nuclear matrix elements for neutrinoless double-beta decay

abstract:
  We show that, within the Quasiparticle Random Phase Approximation (QRPA) and
the renormalized QRPA (RQRPA) based on the Bonn CD nucleon-nucleon interaction,
the competition between the pairing and the neutron-proton particle-particle
and particle-hole interactions causes contributions to the neutrinoless
double-beta decay matrix element to nearly vanish at internucleon distances of
more than 2 or 3 fermis. As a result, the matrix element is more sensitive to
short-range/high-momentum physics than one naively expects. We analyze various
ways of treating that physics and quantify the uncertainty it produces in the
matrix elements, with three different treatments of short-range correlations.


title: Rotating Radio Transients: X-ray observations

abstract:
  Rotating Radio Transients (RRATs) are a new class of neutron stars discovered
through the emission of radio bursts. Eleven sources are known up to now, but
population studies predict these objects to be more numerous than the normal
radio pulsar population. Multiwavelength observations of these peculiar objects
are in progress to disentangle their spectral energy distribution, and then
study in detail their nature. In this review I report on the current state of
the art on these objects, and in particular on the results of new X-ray
observations.


title:
Optical saturation driven by exciton confinement in molecular-chains: a
  TDDFT study

abstract:
  We have identified excitonic confinement in one-dimensional molecular chains
(i.e. polyacetylene and H$_2$) as the main driving force for the saturation of
the chain polarizability as a function of the number of molecular units. This
conclusion is based on first principles time--dependent density functional
theory calculations performed with a new derived exchange--correlation kernel.
The failure of simple local and semi--local functionals is shown to be related
to the lack of memory effects, spatial ultranonlocality, and self--interaction
corrections. These effects get smaller as the gap of the system reduces, in
which case such simple approximations do perform better.


title:
Non-universal gaugino masses and implications on the dark matter and
  Higgs searches

abstract:
  Non-universal boundary conditions in grand unified theories can lead to
non-universal gaugino masses at the unification scale. In R-parity preserving
theories the lightest supersymmetric particle is a natural candidate for the
dark matter. We have studied the composition of the lightest neutralino in
non-universal gaugino mass cases from the SU(5), and implications on the dark
matter. In the representations of SU(5) thermal relic density agreeing with
WMAP is found. The possibility to observe the neutral MSSM Higgs bosons (h/H/A)
at the LHC via neutralino cascades when the lightest neutralino is dark matter,
is discussed for the representation 24, and the connection to dark matter is
established.


title: Covariance, Dynamics and Symmetries, and Hadron Form Factors

abstract:
  We summarise applications of Dyson-Schwinger equations to the theory and
phenomenology of hadrons. Some exact results for pseudoscalar mesons are
highlighted with details relating to the U_A(1) problem. We describe inferences
from the gap equation relating to the radius of convergence for expansions of
observables in the current-quark mass. We recapitulate upon studies of nucleon
electromagnetic form factors, providing a comparison of the ln-weighted ratios
of Pauli and Dirac form factors for the neutron and proton.


title:
Polariton laser using single micropillar GaAs-GaAlAs semiconductor
  cavities

abstract:
  Polariton lasing is demonstrated on the zero dimensional states of single
GaAs/GaAlAs micropillar cavities. Under non resonant excitation, the measured
polariton ground state occupancy is found to be as large as $10^{4}$. Changing
the spatial excitation conditions, competition between several polariton lasing
modes is observed, ruling out Bose-Einstein condensation. When the polariton
state occupancy increases, the emission blueshift is the signature of
self-interaction within the half-light half-matter polariton lasing mode.


title:
Nonlinear Dynamical Equation for Irreversible, Steepest-Entropy-Ascent
  Relaxation to Stable Equilibrium

abstract:
  We discuss the structure and main features of the nonlinear evolution
equation proposed by this author as the fundamental dynamical law within the
framework of Quantum Thermodynamics. The nonlinear equation generates a
dynamical group providing a unique deterministic description of irreversible,
conservative relaxation towards equilibrium from any non-equilibrium state, and
satisfies a very restrictive stability requirement equivalent to
Hatsopoulos-Keenan statement of the second law of thermodynamics. Here, we
emphasize its mathematical structure and its applicability also within other
contexts, such as Classical and Quantum Statistical Mechanics, and Information
Theory.


title: Indirect Searches For Dark Matter: Signals, Hints and Otherwise

abstract:
  For the SUSY 2007 conference, I was asked to review the topic of indirect
searches for dark matter. As part of that talk, I summarized several
observations which have been interpreted as the product of dark matter
annihilations. In my contribution to the proceedings, I have decided to focus
on this aspect of my talk. In particular, I will discuss the cosmic positron
spectrum measured by HEAT, the 511 keV emission from the Galactic Bulge
measured by INTEGRAL, the diffuse galactic and extragalactic gamma ray spectra
measured by EGRET, and the microwave excess from the Galactic Center observed
by WMAP.


title: Distance matrices and isometric embeddings

abstract:
  We review the relations between distance matrices and isometric embeddings
and give simple proofs that distance matrices defined on euclidean and
spherical spaces have all eigenvalues except one non-negative. Several
generalizations are discussed.


title: Reduction of structure for torsors over semilocal rings

abstract:
  Let G be a reductive affine group scheme defined over a semilocal ring k.
Assume that either G is semisimple or k is normal and noetherian. We show that
G has a finite k-subgroup S such that the natural map H^1(R, S) --> H^1(R, G)
is surjective for every semilocal ring R containing k. In other words,
G-torsors over Spec(R) admit reduction of structure to S. We also show that the
natural map H^1(X, S) --> H^1(X, G) is surjective in several other contexts,
under suitable assumptions on the base ring k, the scheme X/k and the group
scheme G/k. These results have already been used to study loop algebras as well
as essential dimension of connected algebraic groups in prime characteristic.
Additional applications are presented at the end of this paper.


title:
Commensurate magnetic structures ofRMn2O5 (R=Y, Ho, Bi) determined by
  Single-crystal Neutron Diffraction

abstract:
  Precise magnetic structures of RMn2O5, with R= Y, Ho, Bi in the
commensurate/ferroelectric regime, have been determined by single-crystal
neutron diffraction. For each system, the integrated intensities of a large
number of independent magnetic Bragg reflections have been measured, allowing
unconstrained least-squares refinement of the structures. The analysis confirms
the previously reported magnetic configuration in the ab-plane, in particular
the existence of zig-zag antiferromagnetic chains. For the Y and Ho compounds
additional weak magnetic components parallel to the c-axis were detected which
are modulated in phase quadrature with the a-b components. This component is
extremely small in the BiMn2O5 sample, therefore supporting symmetric exchange
as the principal mechanism inducing ferroelectricity. For HoMn2O5, a magnetic
ordering of the Ho moments was observed, which is consistent with a
super-exchange interaction through the oxygens. For all three compounds, the
point symmetry in the magnetically ordered state is m2m, allowing the polar
b-axis found experimentally.


title: A Unified Spiral Chain Coloring Algorithm for Planar Graphs

abstract:
  In this paper we have given a unified graph coloring algorithm for planar
graphs. The problems that have been considered in this context respectively,
are vertex, edge, total and entire colorings of the planar graphs. The main
tool in the coloring algorithm is the use of spiral chain which has been used
in the non-computer proof of the four color theorem in 2004. A more precies
explanation of the proof of the four color theorem by spiral chain coloring is
also given in this paper. Then we continue to spiral-chain coloring solutions
by giving the proof of other famous conjectures of Vizing's total coloring and
planar graph conjectures of maximum vertex degree six. We have also given the
proof of a conjecture of Kronk and Mitchem that any plane graph of maximum
degree "Delta" is entirely ("Delta"+4)-colorable.The last part of the paper
deals with the three colorability of planar graphs under the spiral chain
coloring. We have given an efficient and short proof of the Groetzsch's Theorem
that triangle-free planar graphs are 3-colorable.


title:
SuperIso: A program for calculating the isospin asymmetry of B -> K*
  gamma in the MSSM

abstract:
  We present a program for calculating the isospin symmetry breaking of the B
-> K* gamma decay in the MSSM with minimal flavor violation. This program
calculates the NLO supersymmetric contributions to the isospin asymmetry, using
the effective Hamiltonian approach and within the QCD factorization method. We
show that isospin symmetry breaking proves to be a very restrictive observable,
in particular in the mSUGRA parameter space. The program also calculates the
inclusive branching ratio associated to b -> s gamma transition, as a
comparison reference.


title:
Analytic continuation of the critical line in 2-color QCD at nonzero
  temperature and density

abstract:
  We determine the pseudo-critical line in the temperature - chemical potential
plane of 2-color QCD by direct Monte Carlo simulations and by analytic
continuation from imaginary chemical potential.


title: The Quest for the Ideal Scintillator for Hybrid Phototubes

abstract:
  In this paper we present the results of extensive studies of scintillators
for hybrid phototubes with luminescent screens. The results of the developments
of such phototubes with a variety of scintillators are presented. New
scintillator materials for such kind of application are discussed. The
requirements for scintillators to use in such hybrid phototubes are formulated.
It is shown that very fast and highly efficient inorganic scintillators like
ZnO:Ga will be ideal scintillators for such kind of application.

categories: physics.optics astro-ph nucl-ex physics.ins-det


title: The sh-Lie algebra perturbation Lemma

abstract:
  Let R be a commutative ring which contains the rationals as a subring and let
g be a chain complex. Suppose given an sh-Lie algebra structure on g, that is,
a coalgebra perturbation of the coalgebra differential on the cofree
coaugmented differential graded cocommutative coalgebra T' on the suspension of
g and write the perturbed coalgebra as T". Suppose, furthermore, given a
contraction of g onto a chain complex M. We show that the data determine an
sh-Lie algebra structure on M, that is, a coalgebra perturbation of the
coalgebra differential on the cofree coaugmented differential graded
cocommutative coalgebra S' on the suspension of M, a Lie algebra twisting
cochain from the perturbed coalgebra S" to the loop Lie algebra L on the
perturbed coalgebra T", and an extension of this Lie algebra twisting cochain
to a contraction of chain complexes from the Cartan-Chevalley-Eilenberg
coalgebra on L onto S" which is natural in the data. For the special case where
M and g are connected we also construct an explicit extension of the perturbed
retraction to an sh-Lie map. This approach includes a very general solution of
the master equation.


title: Generalized multiresolution analyses with given multiplicity functions

abstract:
  Generalized multiresolution analyses are increasing sequences of subspaces of
a Hilbert space $\H$ that fail to be multiresolution analyses in the sense of
wavelet theory because the core subspace does not have an orthonormal basis
generated by a fixed scaling function. Previous authors have studied a
multiplicity function $m$ which, loosely speaking, measures the failure of the
GMRA to be an MRA. When the Hilbert space $\H$ is $L^2(\mathbb R^n)$, the
possible multiplicity functions have been characterized by Baggett and Merrill.
Here we start with a function $m$ satisfying a consistency condition which is
known to be necessary, and build a GMRA in an abstract Hilbert space with
multiplicity function $m$.


title:
On numerical averaging of the conductivity coefficient using two-scale
  extensions

abstract:
  In this article we compare solutions to elliptic problems having rapidly
oscillated conductivity (permeability, etc) coefficient with solutions to
corresponding homogenized problems obtained from two-scale extensions of the
initial coefficient. The comparison is done numerically on several one and two
dimensional test problems with randomly generated coefficients for different
intensities of oscillation. The dependency of the approximation error on the
size of averaging is investigated.


title:
On coincidence of Alday-Maldacena-regularized $\sigma$-model and
  Nambu-Goto areas of minimal surfaces

abstract:
  For the $\sigma$-model and Nambu-Goto actions, values of the
Alday-Maldacena-regularized actions are calculated on solutions of the
equations of motion with constant non-regularized Lagrangian. It turns out that
these values coincide up to a factor, independent of boundary conditions.


title: Noncommutative Solitons

abstract:
  Solitonic objects play a central role in gauge and string theory (as, e.g.,
monopoles, black holes, D-branes, etc.). Certain string backgrounds produce a
noncommutative deformation of the low-energy effective field theory, which
allows for new types of solitonic solutions. I present the construction, moduli
spaces and dynamics of Moyal-deformed solitons, exemplified in the 2+1
dimensional Yang-Mills-Higgs theory and its Bogomolny system, which is
gauge-fixed to an integrable chiral sigma model (the Ward model).
Noncommutative solitons for various 1+1 dimensional integrable systems (such as
sine-Gordon) easily follow by dimensional and algebraic reduction.
Supersymmetric extensions exist as well and are related to twistor string
theory.


title:
Corrections to Schwarzschild Solution in Noncommutative Gauge Theory of
  Gravity

abstract:
  A deformed Schwarzschild solution in noncommutative gauge theory of
gravitation is obtained. The gauge potentials (tetrad fields) are determined up
to the second order in the noncommutativity parameters $\Theta^{\mu\nu}$. A
deformed real metric is defined and its components are obtained. The
noncommutativity correction to the red shift test of General Relativity is
calculated and it is concluded that the correction is too small to have
observable effects. Implications of such a deformed Schwarzschild metric are
also mentioned.


title: Asymmetric weak-pinning superconducting channels: vortex ratchets

abstract:
  The controlled motion of objects through narrow channels is important in many
fields. We have fabricated asymmetric weak-pinning channels in a
superconducting thin-film strip for controlling the dynamics of vortices. The
lack of pinning allows the vortices to move through the channels with the
dominant interaction determined by the shape of the channel walls. We present
measurements of vortex dynamics in the channels and compare these with similar
measurements on a set of uniform-width channels. While the uniform-width
channels exhibit a symmetric response for both directions through the channel,
the vortex motion through the asymmetric channels is quite different, with
substantial asymmetries in both the static depinning and dynamic flux flow.
This vortex ratchet effect has a rich dependence on magnetic field and driving
force amplitude.


title: Towards Phonon Spectrum of Graphene

abstract:
  It is shown that the nearest neighbor coupling between the carbon atoms is
not enough to reproduce the phonon spectrum as observed in graphene, the second
neighbor force constant is essential. For completeness we have rederived the
phonon spectrum of one dimensional chains and two dimensional lattices like
square lattice and triangular lattice with nearest and next nearest neighbor
coupling among the atoms. This article is essentially an account of the
technical details of a review talk on phonon spectrum of graphene presented at
Institute of Physics.


title: On Direct Verification of Warped Hierarchy-and-Flavor Models

abstract:
  We consider direct experimental verification of warped models, based on the
Randall-Sundrum (RS) scenario, that explain gauge and flavor hierarchies,
assuming that the gauge fields and fermions of the Standard Model (SM)
propagate in the 5D bulk. Most studies have focused on the bosonic Kaluza Klein
(KK) signatures and indicate that discovering gauge KK modes is likely
possible, yet challenging, while graviton KK modes are unlikely to be
accessible at the LHC, even with a luminosity upgrade. We show that direct
evidence for bulk SM fermions, {\it i.e.} their KK modes, is likely also beyond
the reach of a luminosity-upgraded LHC. Thus, neither the spin-2 KK graviton,
the most distinct RS signal, nor the KK SM fermions, direct evidence for bulk
flavor, seem to be within the reach of the LHC. We then consider hadron
colliders with $\sqrt{s} =$ 21, 28, and 60 TeV. We find that discovering the
first KK modes of SM fermions and the graviton typically requires the Next
Hadron Collider (NHC) with $\sqrt{s} \approx 60$ TeV and ${\cal O}(1)$
ab$^{-1}$ of integrated luminosity. If the LHC yields hints of these warped
models, establishing that Nature is described by them, or their 4D CFT duals,
requires an NHC-class machine in the post-LHC experimental program.


title: The yoga of the Cassels-Tate pairing

abstract:
  Cassels has described a pairing on the 2-Selmer group of an elliptic curve
which shares some properties with the Cassels-Tate pairing. In this article, we
prove that the two pairings are the same.


title:
The classification of simple Jacobi--Ricci commuting algebraic curvature
  tensors

abstract:
  We classify algebraic curvature tensors such that the Ricci operator is
simple (i.e. the Ricci operator is complex diagonalizable and either the
complex spectrum consists of a single real eigenvalue or the complex spectrum
consists of a pair of eigenvalues which are complex conjugates of each other)
and which are Jacobi--Ricci commuting (i.e. the Ricci operator commutes with
the Jacobi operator of any vector).


title:
A semigroup approach to wreath-product extensions of Solomon's descent
  algebras

abstract:
  There is a well-known combinatorial definition, based on ordered set
partitions, of the semigroup of faces of the braid arrangement. We generalize
this definition to obtain a semigroup Sigma_n^G associated with G wr S_n, the
wreath product of the symmetric group S_n with an arbitrary group G. Techniques
of Bidigare and Brown are adapted to construct an anti-homomorphism from the
S_n-invariant subalgebra of the semigroup algebra of Sigma_n^G into the group
algebra of G wr S_n. The generalized descent algebras of Mantaci and Reutenauer
are obtained as homomorphic images when G is abelian.


title:
Exponential stability of non-autonomous stochastic partial differential
  equations with finite memory

abstract:
  The exponential stability, in both mean square and almost sure senses, for
energy solutions to a class of nonlinear and non-autonomous stochastic PDEs
with finite memory is investigated. Various criteria for stability are
obtained. An example is presented to demonstrate the main results.


title: Association Rules in the Relational Calculus

abstract:
  One of the most utilized data mining tasks is the search for association
rules. Association rules represent significant relationships between items in
transactions. We extend the concept of association rule to represent a much
broader class of associations, which we refer to as \emph{entity-relationship
rules.} Semantically, entity-relationship rules express associations between
properties of related objects. Syntactically, these rules are based on a broad
subclass of safe domain relational calculus queries. We propose a new
definition of support and confidence for entity-relationship rules and for the
frequency of entity-relationship queries. We prove that the definition of
frequency satisfies standard probability axioms and the Apriori property.


title:
Supersymmetry Breaking and Radius Stabilization by Constant Boundary
  Superpotentials in Warped Space

abstract:
  Supersymmetry breaking and radius stabilization by constant superpotentials
localized at boundaries is studied in a supersymmetric warped space model where
a hypermultiplet, a compensator and a radion multiplet are taken into account.
Soft mass induced by the anomaly mediation can be of the order of 100GeV and
can be dominant compared to that mediated by bulk fields. A lighter physical
mode composed of the radion and the moduli can have mass of the order of a TeV
and the gravitino mass can be of the order of 10^7 GeV. The radius is
stabilized by the presence of the constant boundary superpotentials. We also
find that the mass splitting has an interesting dependence on the bulk mass
parameter c.


title: Screening masses in the SU(3) pure gauge theory and universality

abstract:
  We determine from Polyakov loop correlators the screening masses in th e
deconfined phase of the (3+1)d SU(3) pure gauge theory at finite temperature
near transition, for two different channels of angular momentum and parity.
Their ratio is compared with that of the massive excitations with the same
quantum numbers in the 3d 3-state Potts model in the broken phase near the
transition point at zero magnetic field. Moreover we study the inverse decay
length of the correlation between the real parts and between the imaginary
parts of the Polyakov loop and compare the results with expectations from
perturbation theory and mean-field Polyakov loop models.


title: Strings on conifolds from strong coupling dynamics, part I

abstract:
  A method to solve various aspects of the strong coupling expansion of the
superconformal field theory duals of AdS_5 x X geometries from first principles
is proposed. The main idea is that at strong coupling the configurations that
dominate the low energy dynamics of the field theory compactified on a three
sphere are given by certain non-trivial semi-classical configurations in the
moduli space of vacua.
  We show that this approach is self-consistent and permits one to express most
of the dynamics in terms of an effective N=4 SYM dynamics. This has the
advantage that some degrees of freedom that move the configurations away from
moduli space can be treated perturbatively, unifying the essential low energy
dynamics of all of these theories. We show that with this formalism one can
compute the energies of strings in the BMN limit in the Klebanov-Witten theory
from field theory considerations, matching the functional form of results found
using AdS geometry. This paper also presents various other technical results
for the semiclassical treatment of superconformal field theories.


title:
Impact of slepton generation mixing on the search for sneutrinos -
  Lepton flavour violation in sneutrino production and decays in the general
  MSSM

abstract:
  We perform a systematic study of sneutrino production and decays in the
Minimal Supersymmetric Standard Model (MSSM) with slepton generation mixing. We
study bosonic decays like sneutrino \to slepton^- + W^+/H^+ as well as
fermionic ones. We show that the effect of slepton generation mixing on the
sneutrino production and decays can be quite large in a significant part of the
MSSM parameter space despite the very strong experimental limits on lepton
flavour violating processes. This could have an important impact on the search
for sneutrinos and the determination of the MSSM parameters at future
colliders, such as LHC, ILC, CLIC and muon collider.


title: Multiplicative function instead of logarithm (an elementary approach)

abstract:
  V.I. Arnold has recently defined the complexity of finite sequences of zeroes
and ones in terms of periods and preperiods of attractors of a dynamic system
of the operator of finite differentiation. Arnold has set up a hypothesis that
the sequence of the values of the logarithm is most complicated or almost most
complicated. In this paper we obtain the necessary and sufficient conditions
which make this sequence (supplemented with zero) most complicated for a more
wide class of operators. We prove that a sequence of values of a multiplicative
function in a finite field is most complicated or almost most complicated for
any operator divisible by the differentiation operator.


title: Tailoring polarization entanglement in anisotropy-compensated SPDC

abstract:
  We show that the angular spectrum of type-II SPDC contains a continuum of
maximally entangled states. For the realization of a bright source of entangled
two-photon states, a standard technique is to compensate for the transverse
walk-off in the production crystal. We demonstrate that polarization entangled
states can be effectively engineered by generalizing this approach. Our method
allows to considerably enrich the set of generated entangled states with a
controlled tailoring them.


title: Dynamical systems with double recursion are undecidable

abstract:
  A primitive type of two-dimensional dynamic system is introduced. It is shown
that there is no decision procedure able to answer if such a dynamical system
is ultimately zero.


title: Slow and fast micro-field components in warm and dense hydrogen plasmas

abstract:
  The aim of this work is the investigation of the statistical properties of
local electric fields in an ion-electron two component plasmas for coupled
conditions. The stochastic fields at a charged or at a neutral point in plasmas
involve both slow and fast fluctuation characteristics. The statistical study
of these local fields based on a direct time average is done for the first
time. For warm and dense plasma conditions, typically $N_{e}\approx
10^{18}cm^{-3}$, $% T_{e}\approx 1eV$, well controlled molecular dynamics (MD)
simulations of neutral hydrogen, protons and electrons have been carried out.
Relying on these \textit{ab initio} MD calculations this work focuses on an
analysis of the concepts of statistically independent slow and fast local field
components, based on the consideration of a time averaged electric field. Large
differences are found between the results of these MD simulations and
corresponding standard results based on static screened fields. The effects
discussed are of importance for physical phenomena connected with stochastic
electric field fluctuations, e.g., for spectral line broadening in dense
plasmas.


title: Self-similarity of complex networks and hidden metric spaces

abstract:
  We demonstrate that the self-similarity of some scale-free networks with
respect to a simple degree-thresholding renormalization scheme finds a natural
interpretation in the assumption that network nodes exist in hidden metric
spaces. Clustering, i.e., cycles of length three, plays a crucial role in this
framework as a topological reflection of the triangle inequality in the hidden
geometry. We prove that a class of hidden variable models with underlying
metric spaces are able to accurately reproduce the self-similarity properties
that we measured in the real networks. Our findings indicate that hidden
geometries underlying these real networks are a plausible explanation for their
observed topologies and, in particular, for their self-similarity with respect
to the degree-based renormalization.


title: Boundary action of the H3+ model

abstract:
  We find the boundary action for Euclidean AdS2 D-branes in H3+. This action
is consistent with the D-branes' symmetries and with the H3+-Liouville relation
for disc correlators. It can be used for performing free-field calculations in
the H3+ model with boundaries. We explicitly perform the Coulomb-like integrals
which appear in the free-field calculation of the bulk one-point function, and
find agreement with previously known conformal bootstrap results.


title:
Improving Guess Geminals for the Geminal Mean Field Configuration
  Interaction Method

abstract:
  The purpose of this letter is to show that a rotation of Hartree-Fock
canonical orbitals which minimizes the lowest eigenvalues of a configuration
interaction calculation limited to the mono-excitated configurations from a
given orbital allows one to construct a better starting guess for the geminal
mean field configuration interaction method.


title: Entanglement in spatially inhomogeneous many-fermion systems

abstract:
  We investigate entanglement of strongly interacting fermions in spatially
inhomogeneous environments. To quantify entanglement in the presence of spatial
inhomogeneity, we propose a local-density approximation (LDA) to the
entanglement entropy, and a nested LDA scheme to evaluate the entanglement
entropy on inhomogeneous density profiles. These ideas are applied to models of
electrons in superlattice structures with different modulation patterns,
electrons in a metallic wire in the presence of impurities, and phase-separated
states in harmonically confined many-fermion systems, such as electrons in
quantum dots and atoms in optical traps. We find that the entanglement entropy
of inhomogeneous systems is strikingly different from that of homogeneous
systems.


title: A geometric approach to full Colombeau algebras

abstract:
  We present a geometric approach to diffeomorphism invariant full Colombeau
algebras which allows a particularly clear view on the construction of the
intrinsically defined algebra $\hat{\mathcal G}(M)$ on the manifold $M$ given
in (Grosser et al., Adv. Math. 166 (2002), 179--206).


title: The algebra of Wilson-'t Hooft operators

abstract:
  We study the Operator Product Expansion of Wilson-'t Hooft operators in a
twisted N=4 super-Yang-Mills theory with gauge group G. The Montonen-Olive
duality puts strong constraints on the OPE and in the case G=SU(2) completely
determines it. From the mathematical point of view, the Montonen-Olive duality
predicts the L^2 Dolbeault cohomology of certain equivariant vector bundles on
Schubert cells in the affine Grassmannian. We verify some of these predictions.
We also make some general observations about higher categories and defects in
Topological Field Theories.


title: Propositional systems, Hilbert lattices and generalized Hilbert spaces

abstract:
  With this chapter we provide a compact yet complete survey of two most
remarkable "representation theorems": every arguesian projective geometry is
represented by an essentially unique vector space, and every arguesian Hilbert
geometry is represented by an essentially unique generalized Hilbert space. C.
Piron's original representation theorem for propositional systems is then a
corollary: it says that every irreducible, complete, atomistic, orthomodular
lattice satisfying the covering law and of rank at least 4 is isomorphic to the
lattice of closed subspaces of an essentially unique generalized Hilbert space.
Piron's theorem combines abstract projective geometry with lattice theory. In
fact, throughout this chapter we present the basic lattice theoretic aspects of
abstract projective geometry: we prove the categorical equivalence of
projective geometries and projective lattices, and the triple categorical
equivalence of Hilbert geometries, Hilbert lattices and propositional systems.


title:
The structure and properties of vacancies in Si nano-crystals calculated
  by real-space pseudopotential methods

abstract:
  The structure and properties of vacancies in a 2 nm Si nano-crystal are
studied using a real space density functional theory/pseudopotential method. It
is observed that a vacancy's electronic properties and energy of formation are
directly related to the local symmetry of the vacancy site. The formation
energy for vacancies and Frenkel pair are calculated. It is found that both
defects have lower energy in smaller crystals. In a 2 nm nano-crystal the
energy to form a Frenkel pair is 1.7 eV and the energy to form a vacancy is no
larger than 2.3 eV. The energy barrier for vacancy diffusion is examined via a
nudged elastic band algorithm.


title:
Kaon semileptonic decay form factors from N_f = 2 non-perturbatively
  O(a)-improved Wilson fermions

abstract:
  We present first results from the QCDSF collaboration for the kaon
semileptonic decay form factors at zero momentum transfer, using two flavours
of non-perturbatively O(a)-improved Wilson quarks. A lattice determination of
these form factors is of particular interest to improve the accuracy on the CKM
matrix element |V_us|. Calculations are performed on lattices with lattice
spacing of about 0.08 fm with different values of light and strange quark
masses, which allows us to extrapolate to chiral limit. Employing double ratio
techniques, we are able to get small statistical errors.


title: Order one invariants of spherical curves

abstract:
  We give a complete description of all order 1 invariants of spherical curves.
We also identify the subspaces of all J-invariants and S-invariants, and
present two equalities satisfied by any spherical curve.