title: Effect of Spin-Torsion Interaction on Raychaudhuri Equation

abstract:
  Raychaudhuri equation is generalized in the parameterized absolute
parallelism geometry. This version of absolute parallelism is more general than
the conventional one. The generalization takes into account the suggested
interaction between the quantum spin of the moving elementary particle and the
torsion of the background gravitational field. The generalized Raychaudhuri
equation obtained contains some extra terms, depending on the torsion of
space-time, that would have some effects on the singularity theorems of general
relativity. Under a certain condition, this equation could be reduced to the
original Raychaudhuri equation without any need for a vanishing torsion.


title:
Optimum and quasi-optimum doped superconducting phases in FeAs and
  Fe2As2 superconductors

abstract:
  We have developed a real space spin-parallel theory of superconductivity
based on the minimum principle in energy. This theory has successfully provided
coherent explanations to a number of complicated problems in conventional and
non-conventional superconductors. In this paper, we report the study the
optimal doping problem in the new oxypnictide high-temperature superconductors
using aforementioned theory. In FeAs family, it is shown that there are three
optimum (or quasi-optimum) doped phases at doping levels x1=1/3, 1/6 and 1/8,
where the vortex lattice forms square or triangular stable configurations.
While in Fe2As2 family, the optimal dopings occur at x2=2/5 and 1/2 with square
and triangular superconducting vortex line lattices, respectively.


title: Polytopes with mass linear functions, part I

abstract:
  We analyze mass linear functions $H$ on simple polytopes $\De$, where a mass
linear function is an affine function on $\De$ whose value on the center of
mass depends linearly on the positions of the supporting hyperplanes. We show
that certain types of symmetries of $\De$ give rise to nonconstant mass linear
functions on $\De$. These are called inessential; the others are essential. We
also show that most polytopes do not admit any nonconstant mass linear
functions. Our main result shows that there is only one family of smooth
polytopes of dimension $\leq 3$ which admit essential mass linear functions.
  These results have geometric implications. Fix a symplectic toric manifold
$(M,\om,T,\Phi)$ with moment polytope $\De = \Phi(M)$; let $\Symp(M,\om)$ be
its group of symplectomorphisms. Any linear function $H$ on $\De$ generates a
Hamiltonian $\R$ action on $M$ whose closure is a subtorus $T_H$ of $T$. We
show that if the map $\pi_1(T_H)\to \pi_1(\Symp(M,\om))$ has finite image, then
$H$ is mass linear. Therefore, in most cases the induced map $\pi_1(T) \to
\pi_1(\Symp(M,\om))$ is an injection. We also show that this map does not have
finite image unless $M$ is a product of projective spaces. Moreover, the
inessential $H$ correspond to elements in the kernel of the map $\pi_1(T)\to
\Isom(M)$, where the Kahler isometry group $\Isom(M)\subset \Symp(M,\om)$
consists of elements that also preserve the natural compatible complex
structure on $M$. Therefore if $\De$ supports no nonconstant essential mass
linear $H$, the map $\pi_1(\Isom(M))\to pi_1(\Symp(M,\om)$ is injective.


title: Simple modules over factorpowers

abstract:
  In this paper we study complex representations of the factorpower $\fp(G,M)$
of a finite group $G$ acting on a finite set $M$. This includes the finite
monoid $\FP$, which can be seen as a kind of a ``balanced'' generalization of
the symmetric group $S_n$ inside the semigroup of all binary relations. We
describe all irreducible representations of $\fp(G,M)$ and relate them to
irreducible representations of certain inverse semigroups. In particular,
irreducible representations of $\FP$ are related to irreducible representations
of the maximal factorizable submonoid of the dual symmetric inverse monoid. We
also show that in the latter cases irreducible representations lead to an
interesting combinatorial problem in the representation theory of $S_n$, which,
in particular, is related to Foulkes' conjecture. Finally, we show that all
simple $\fp(G,M)$-modules are unitarizable and that tensor products of simple
$\fp(G,M)$-modules are completely reducible.


title: Statistical physics of dyons and confinement

abstract:
  We present a semiclassical description of the SU(N) Yang--Mills theory whose
partition function at nonzero temperatures is approximated by that of an
ensemble of N kinds of interacting dyons. The ensemble is mathematically
described by an exactly solvable 3d quantum field theory, allowing calculation
of correlations functions relevant to confinement. We show that all known
criteria of confinement are satisfied in this semiclassical approximation: (i)
the average Polyakov line is zero below some critical temperature, and nonzero
above it, (ii) static quarks in any nonzero N-ality representation have linear
rising potential energy, (iii) the average spatial Wilson loop falls off
exponentially with the area, (iv) N^2 gluons are canceled out from the
spectrum, (v) the critical temperature is in good agreement with lattice data.


title: Frame-like Actions for Massless Mixed-Symmetry Fields in Minkowski space

abstract:
  A frame-like action for arbitrary mixed-symmetry bosonic massless fields in
Minkowski space is constructed. The action is given in a simple form and
consists of two terms for a field of any spin. The fields and gauge parameters
are certain tensor-valued differential forms. The formulation is based on the
unfolded form of equations for mixed-symmetry fields.


title:
The gamma Dor CoRoT target HD49434. I-Results from the ground-based
  campaign

abstract:
  Context: We present the results of an extensive ground-based photometric and
spectroscopic campaign on the gamma Dor CoRoT target HD49434. This campaign was
preparatory to the CoRoT satellite observations, which took place from October
2007 to March 2008. Results: The frequency analysis clearly shows the presence
of four frequencies in the 0.2-1.7 c/d interval, as well as six frequencies in
the 5-12 c/d domain. The low frequencies are typical for gamma Dor variables
while the high frequencies are common for delta Sct pulsators. We propose the
frequency 2.666 c/d as a possible rotational frequency. All modes, for which an
identification was possible, seem to be high-degree modes (3 <= l <= 8). We did
not find evidence for a possible binary nature of HD49434. The element
abundances we derived are consistent with the values obtained in previous
analyses. Conclusions: We classify the gamma Dor star HD49434 as a hybrid
pulsator, which pulsates simultaneously in p- and g-modes. This finding makes
HD49434 an extremely interesting target for asteroseismic modelling.
Observations: Based on observations made with the 2.2m ESO/MPI telescope at the
La Silla Observatory under the ESO Large Programme: LP178.D-0361. Also based on
observations obtained at Observatorio de Sierra Nevada (Spain), at the Centro
Astronomico Hispano Aleman at Calar Alto (Spain), at Observatorio Astronomico
Nacional San Pedro Martir (Mexico), at the Piszkesteto Mountain Station of
Konkoly Observatory (Hungary), at Observatoire de Haute Provence (France) and
at Mount John University Observatory (New Zealand).


title: Cyclic and finite surgeries on Montesinos knots

abstract:
  We give a complete classification of the Dehn surgeries on Montesinos knots
which yield manifolds with cyclic or finite fundamental groups.


title: Low voltage control of ferromagnetism in a semiconductor p-n junction

abstract:
  The concept of low-voltage depletion and accumulation of electron charge in
semiconductors, utilized in field-effect transistors (FETs), is one of the
cornerstones of current information processing technologies. Spintronics which
is based on manipulating the collective state of electron spins in a
ferromagnet provides complementary technologies for reading magnetic bits or
for the solid-state memories. The integration of these two distinct areas of
microelectronics in one physical element, with a potentially major impact on
the power consumption and scalability of future devices, requires to find
efficient means for controlling magnetization electrically. Current induced
magnetization switching phenomena represent a promising step towards this goal,
however, they relay on relatively large current densities. The direct approach
of controlling the magnetization by low-voltage charge depletion effects is
seemingly unfeasible as the two worlds of semiconductors and metal ferromagnets
are separated by many orders of magnitude in their typical carrier
concentrations. Here we demonstrate that this concept is viable by reporting
persistent magnetization switchings induced by short electrical pulses of a few
volts in an all-semiconductor, ferromagnetic p-n junction.


title:
Generation of entangled channels for perfect teleportation channels
  using multi-electron quantum dots

abstract:
  In this work we have proposed a scheme for generating $N$ qubit entangled
states which can teleport an unknown state perfectly. By switching on the
exchange interaction ($J$) between the qubits one can get the desired states
periodically. A multi electron quantum dot can be a possible realization for
generating such $N$ qubit states with high fidelity. In the limit of $N \to
\infty$, there exists a unique time $t=\frac{1}{J}\cos^{-1}(-1/8)$ where the
Hamiltonian dynamics gives the $N$ qubit state that can assist perfect
teleportation. We have also discussed the effect of the nuclear spin
environment on the fidelity of teleportation for a general $N$ qubit entangled
channel.


title:
The Correspondence Analysis Platform for Uncovering Deep Structure in
  Data and Information

abstract:
  We study two aspects of information semantics: (i) the collection of all
relationships, (ii) tracking and spotting anomaly and change. The first is
implemented by endowing all relevant information spaces with a Euclidean metric
in a common projected space. The second is modelled by an induced ultrametric.
A very general way to achieve a Euclidean embedding of different information
spaces based on cross-tabulation counts (and from other input data formats) is
provided by Correspondence Analysis. From there, the induced ultrametric that
we are particularly interested in takes a sequential - e.g. temporal - ordering
of the data into account. We employ such a perspective to look at narrative,
"the flow of thought and the flow of language" (Chafe). In application to
policy decision making, we show how we can focus analysis in a small number of
dimensions.


title:
Electron-Positron Pair Production in Space- or Time-Dependent Electric
  Fields

abstract:
  Treating the production of electron and positron pairs by a strong electric
field from the vacuum as a quantum tunneling process we derive, in
semiclassical approximation, a general expression for the pair production rate
in a $z$-dependent electric field $E(z)$ pointing in the $z$-direction. We also
allow for a smoothly varying magnetic field parallel to $E(z)$. The result is
applied to a confined field $E(z)\not=0$ for $|z|\lesssim \ell $, a
semi-confined field $E(z)\not=0$ for $ z\gtrsim 0 $, and a linearly increasing
field $E(z)\sim z$. The boundary effects of the confined fields on
pair-production rates are exhibited. A simple variable change in all formulas
leads to results for electric fields depending on time rather than space.
  In addition, we discuss tunneling processes in which empty atomic bound
states are spontaneously filled by negative-energy electrons from the vacuum
under positron emission. In particular, we calculate the rate at which the
atomic levels of a bare nucleus of finite size $r_{\rm n}$ and large $Z\gg 1$
are filled by spontaneous pair creation.


title: Canonical Nonlinear Connections in the Multi-Time Hamilton Geometry

abstract:
  In this paper we study some geometrical objects (d-tensors, multi-time
semisprays of polymomenta and nonlinear connections) on the dual 1-jet vector
bundle $J^{1*}(\cal{T}, M)\to \cal{T}\times M$. Some geometrical formulas,
which connect the last two geometrical objects, are also derived. Finally, a
canonical nonlinear connection produced by a Kronecker $h$-regular multi-time
Hamiltonian is given.


title: Gluonium states and the Pomeron trajectory

abstract:
  Pomeron is modeled as a system of two interacting by the Cornell potential
massive gluons. In bound state region, a relativistic wave equation for the
potential is analized. Two exact asymptotic solutions of the equation are used
to derive an interpolating mass formula for gluonium states and the Pomeron
trajectory in the whole region. The trajectory obtained is linear at large
timelike $t$ and flattens off at -1 in the scattering region at large $-t$.
Parameters of the trajectory are found from the fit of recent HERA data for
$\alpha_P(t)$.


title:
On similarity and pseudo-similarity solutions of Falkner-Skan boundary
  layers

abstract:
  The present work deals with the two-dimensional incompressible,laminar,
steady-state boundary layer equations. First, we determinea family of velocity
distributions outside the boundary layer suchthat these problems may have
similarity solutions. Then, we examenin detail new exact solutions, called
Pseudo--similarity, where the external velocity varies inversely-linear with
the distance along the surface $ (U_e(x) = U_\infty x^{-1}). The present work
deals with the two-dimensional incompressible, laminar, steady-state boundary
layer equations. First, we determine a family of velocity distributions outside
the boundary layer such that these problems may have similarity solutions.
Then, we examenin detail new exact solutions. The analysis shows that solutions
exist only for a lateral suction. For specified conditions, we establish the
existence of an infinite number of solutions, including monotonic solutions and
solutions which oscillate an infinite number of times and tend to a certain
limit. The properties of solutions depend onthe suction parameter. Furthermore,
making use of the fourth--order Runge--Kutta scheme together with the shooting
method, numerical solutions are obtained.


title: On a $p$--Laplace equation with multiple critical nonlinearities

abstract:
  Using the Mountain--Pass Theorem of Ambrosetti and Rabinowitz we prove that
$-\Delta_p u-\mu|x|^{-p}{u^{p-1}}=|x|^{-s}{u^{\crits-1}}+u^{\crit-1}$ admits a
positive weak solution in $\rn$ of class $\dunp\cap C^1(\rn\setminus\{0\})$,
whenever $\mu<\mu_1$, and $\mu_1=[(n-p)/p]^p$. The technique is based on the
existence of extremals of some Hardy--Sobolev type embeddings of independent
interest. We also show that if $u\in\dunp$ is a weak solution in $\rn$ of
$-\Delta_p u-\mu|x|^{-p}{|u|^{p-2}u}=|x|^{-s}{|u|^{\crits-2}u}+|u|^{q-2}u$,
then $u\equiv0$ when either $1<q<\crit$, or $q>\crit$ and $u$ is also of class
$L^\infty_\text{\scriptsize{loc}}(\rn\setminus\{0\})$.


title:
On the symmetry of ascents and descents over 01-fillings of moon
  polyominoes

abstract:
  The purpose of this short paper is to put recent results on the symmetry of
the joint distribution of the numbers of crossings and nestings of two edges
over matchings, set partitions and linked partitions, in the larger context of
the enumeration of increasing and decreasing chains of length 2 in fillings of
moon polyominoes.


title:
Developments in the evaluation of m_c dependent matrix elements in B ->
  Xs gamma at NNLO

abstract:
  The full prediction of the inclusive radiative B -> Xs gamma decay rate at
NNLO requires a complete evaluation of missing charm quark mass dependent
matrix elements. Recent developments in the on-going computations are reported
and the current status is briefly overviewed.


title: Generating the mapping class group of a punctured surface by involutions

abstract:
  Let $\Sigma_{g,b}$ denote a closed orientable surface of genus $g$ with $b$
punctures and let $\rm Mod(\Sigma_{\textit{g,b}})$ denote its mapping class
group. In [Luo] Luo proved that if the genus is at least 3, $\rm
Mod(\Sigma_{\textit{g,b}})$ is generated by involutions. He also asked if there
exists a universal upper bound, independent of genus and the number of
punctures, for the number of torsion elements/involutions needed to generate
$\rm Mod(\Sigma_{\textit{g,b}})$. Brendle and Farb [BF] gave an answer in the
case of $g\geq 3, b=0$ and $g\geq 4, b=1$, by describing a generating set
consisting of 6 involutions. Kassabov showed that for every $b$ $\rm
Mod(\Sigma_{\textit{g,b}})$ can be generated by 4 involutions if $g\geq 8$, 5
involutions if $g\geq 6$ and 6 involutions if $g\geq 4$. We proved that for
every $b$ $\rm Mod(\Sigma_{\textit{g,b}})$ can be generated by 4 involutions if
$g\geq 7$ and 5 involutions if $g\geq 5$.


title:
The New Minimal Supersymmetric GUT : Spectra, RG analysis and Fermion
  Fits

abstract:
  The supersymmetric SO(10) GUT based on the ${\bf{210\oplus 10\oplus 120\oplus
126\oplus {\bar {126}}}}$ Higgs system provides a minimal framework for the
emergence of the R-parity exact MSSM at low energies and a viable
supersymmetric seesaw explanation for the observed neutrino masses and mixing
angles. We present formulae for MSSM decomposition of the superpotential
invariants, tree level light charged fermion effective Yukawa couplings,
Weinberg neutrino mass generation operator, and the $d=5,\Delta B=\Delta L \neq
0$ effective superpotential in terms of GUT parameters. We use them to
determine fits of the 18 available fermion mass-mixing data in terms of the
superpotential parameters of the NMSGUT and SUGRY(NUHM) type soft supersymmetry
breaking parameters ($\{m_{\tilde f},m_{1/2},A_0,M^2_{H,\bar H}\} $) specified
at the MSSM one loop unification scale $M_X^0=10^{16.33} $ GeV. Our fits are
compatible with electroweak symmetry breaking and Unification constraints and
yield right-handed neutrino masses in the leptogenesis relevant range :
$10^8-10^{13} $ GeV. Matching the SM data requires lowering the strange and
down quark Yukawas in the MSSM via large $\tan\beta$ driven threshold
corrections and characteristic soft Susy breaking spectra. The Susy spectra
have light pure Bino LSP, heavy exotic Higgs(inos) and large $
\mu,A_0,M_{H,\bar{H}}$ parameters $\sim 100$ TeV. Typically third generation
sfermions are much \emph{heavier} than the first two generations. The smuon is
often the lightest charged sfermion thus offering a Bino-CDM co-annihilation
channel. The parameter sets obtained are used to calculate B violation rates
which are found to be generically much faster($\sim 10^{-28}\, yr^{-1}$) than
the current experimental limits. Improvements which may allow acceptable B
violation rates are identified.


title: Enhanced Ferromagnetic Stability in Cu Doped Passivated GaN Nanowires

abstract:
  Density functional calculations are performed to investigate the room
temperature ferromagnetism in GaN:Cu nanowires (NWs). Our results indicate that
two Cu dopants are most stable when they are near each other. Compared to bulk
GaN:Cu, we find that magnetization and ferromagnetism in Cu doped NWs is
strongly enhanced because the band width of the Cu td band is reduced due to
the 1D nature of the NW. The surface passivation is shown to be crucial to
sustain the ferromagnetism in GaN:Cu NWs. These findings are in good agreement
with experimental observations and indicate that ferromagnetism in this type of
systems can be tuned by controlling the size or shape of the host materials.


title:
Prompt high-energy neutrinos from gamma-ray bursts in photospheric and
  synchrotron self-Compton scenarios

abstract:
  We investigate neutrino emission from gamma-ray bursts (GRBs) under
alternative scenarios for prompt emission (the photospheric and synchrotron
self-Compton scenarios) rather than the classical optically thin synchrotron
scenario. In the former scenario, we find that neutrinos from the pp reaction
can be very important at energies around 10-100 TeV. They may be detected by
IceCube/KM3Net and useful as a probe of baryon acceleration around/below the
photosphere. In the latter scenario, we may expect about EeV pgamma neutrinos
produced by soft photons. Predicted spectra are different from that in the
classical scenario, and neutrinos would be useful as one of the clues to the
nature of GRBs (the jet composition, emission radius, magnetic field and so
on).


title:
The Inhomogeneous Background of H2 Dissociating Radiation During Cosmic
  Reionization

abstract:
  The first, self-consistent calculations of the cosmological H_2 dissociating
UV background produced during the epoch of reionization (EOR) by the sources of
reionization are presented. Large-scale radiative transfer simulations of
reionization trace the impact of all the ionizing starlight on the IGM from all
the sources in our simulation volume down to dwarf galaxies of mass ~ 10^8
solar mass, identified by very high-resolution N-body simulations, including
the self-regulating effect of IGM photoheating on dwarf galaxy formation. The
UV continuum emitted below 13.6 eV by each source is then transferred through
the same IGM, attenuated by atomic H Lyman series resonance lines, to predict
the evolution of the inhomogeneous background in the Lyman-Werner band of H_2
between 11 and 13.6 eV.


title:
Multiorder, Kleene stars and cyclic projectors in the geometry of max
  cones

abstract:
  This paper summarizes results on some topics in the max-plus convex geometry,
mainly concerning the role of multiorder, Kleene stars and cyclic projectors,
and relates them to some topics in max algebra. The multiorder principle leads
to max-plus analogues of some statements in the finite-dimensional convex
geometry and is related to the set covering conditions in max algebra. Kleene
stars are fundamental for max algebra, as they accumulate the weights of
optimal paths and describe the eigenspace of a matrix. On the other hand, the
approach of tropical convexity decomposes a finitely generated semimodule into
a number of convex regions, and these regions are column spans of uniquely
defined Kleene stars. Another recent geometric result, that several semimodules
with zero intersection can be separated from each other by max-plus halfspaces,
leads to investigation of specific nonlinear operators called cyclic
projectors. These nonlinear operators can be used to find a solution to
homogeneous multi-sided systems of max-linear equations. The results are
presented in the setting of max cones, i.e., semimodules over the max-times
semiring.


title: Polarized superfluids near their tricritical point

abstract:
  We obtain a variety of predictions for the properties of
population-imbalanced (or polarized) fermionic superfluids near their
tricritical point. In the vicinity of the high-symmetry tricritical point,
observable quantities such as the cloud shape, heat capacity, and local
polarization should exhibit distinct behavior arising from the tricritical
scaling laws, as well as logarithmic corrections to scaling reflecting the
marginal nature of interactions.


title: On the Conformal Field Theories for Bosonic Strings in PP-Waves

abstract:
  Recently Kazama and Yokoi (arXiv:0801.1561 [hep-th]) have used a phase-space
method to study the Virasoro algebra of type IIB superstring theory in the
maximally supersymmetric R-R plane wave background in a semi-light-cone gauge.
Two types of normal ordering have been considered, namely "phase space normal
ordering" (PNO) and "massless normal ordering" (MNO). The second one, which is
the right one to choose in flat background, has been discarded with the
argument that the Virasoro algebra closes only in the first case. To understand
this issue better with a completely covariant treatment we consider the easiest
case of bosonic strings propagating in an arbitrary pp-wave of the simplest
kind. Using the phase-space method we show that MNO is in fact the right one to
choose because of the following reason. For both types of normal ordering the
energy-momentum tensor satisfies the desired Virasoro algebra up to anomalous
terms proportional to the space-time equation of motion of the background.
However, it is MNO which gives rise to the correct spectrum - we compute the
quadratic space-time action by restricting the string field inside a transverse
Hilbert space. This turns out to be non-diagonal. Diagonalizing this action
reproduces the spectrum directly obtained in light-cone quantization. The same
method with PNO gives rise to a spectrum with negative dimensions.


title:
The emptiness of voids: yet another over-abundance problem for the LCDM
  model

abstract:
  We study the luminosity function, the peculiar velocities, and the sizes of
voids in the Local Volume (LV) in observational samples of galaxies which
contain galaxies down to MB=-10-12 within the distance 4-8Mpc. Comparing the
results with the predictions of the standard cosmological LCDM model, we find
that the theory faces a sever problem: it predicts a factor of ten more dwarf
haloes as compared with the observed number of dwarf galaxies. In the LV we
identify voids with sizes ranging from 1 to 4.5Mpc and compare the
observational distribution of void sizes with the voids in very high resolution
simulations of the LCDM model with WMAP1 and WMAP3 parameters. The theoretical
void function matches the observations remarkably well only if we use haloes
with circular velocities Vc larger than 40-45 km/s (Mvir=(1-2)e10msun) for
models with with sigma8 = 0.9 and Vc>35km/s (Mvir=(6-8)e9msun) for sigma8 =
0.75. We exclude the possibility that in the LCDM model haloes with circular
velocities < 35km/s can host galaxies as bright as MB=-12: there are too many
small haloes in the LCDM model resulting in voids being too small as compared
with the observations. The problem is that many of the observed dwarf galaxies
have HI rotational velocities below 25km/s that strictly contradicts the LCDM
predictions. Thus, the LCDM model faces the same overabundance problem, which
it had with the number of satellites in the LG. We also estimate the rms
deviations from the Hubble flow sigmaH and find that in most of our model
LV-candidates the rms peculiar velocities are consistent with observational
values sigmaH=50km/s for distances less than 3Mpc and sigmaH=80km/s for
distances less than 8Mpc. At distances 4 (8) Mpc, the observed overdensities of
galaxies are 3.5-5.5 (1.3-1.6) -- significantly larger than typically assumed.


title: Stochastic resonance and the trade arrival rate of stocks

abstract:
  We studied non-dynamical stochastic resonance for the number of trades in the
stock market. The trade arrival rate presents a deterministic pattern that can
be modeled by a cosine function perturbed by noise. Due to the nonlinear
relationship between the rate and the observed number of trades, the noise can
either enhance or suppress the detection of the deterministic pattern. By
finding the parameters of our model with intra-day data, we describe the
trading environment and illustrate the presence of SR in the trade arrival rate
of stocks in the U.S. market.


title: Second-order elliptic equations with variably partially VMO coefficients

abstract:
  The solvability in $W^{2}_{p}(\bR^{d})$ spaces is proved for second-order
elliptic equations with coefficients which are measurable in one direction and
VMO in the orthogonal directions in each small ball with the direction
depending on the ball. This generalizes to a very large extent the case of
equations with continuous or VMO coefficients.


title:
Generalized Bose-Fermi statistics and structural correlations in
  weighted networks

abstract:
  We derive a class of generalized statistics, unifying the Bose and Fermi
ones, that describe any system where the first-occupation energies or
probabilities are different from subsequent ones, as in presence of thresholds,
saturation, or aging. The statistics completely describe the structural
correlations of weighted networks, which turn out to be stronger than expected
and to determine significant topological biases. Our results show that the null
behavior of weighted networks is different from what previously believed, and
that a systematic redefinition of weighted properties is necessary.

categories: physics.soc-ph cond-mat.stat-mech physics.data-an quant-ph


title: Bloomier Filters: A second look

abstract:
  A Bloom filter is a space efficient structure for storing static sets, where
the space efficiency is gained at the expense of a small probability of
false-positives. A Bloomier filter generalizes a Bloom filter to compactly
store a function with a static support. In this article we give a simple
construction of a Bloomier filter. The construction is linear in space and
requires constant time to evaluate. The creation of our Bloomier filter takes
linear time which is faster than the existing construction. We show how one can
improve the space utilization further at the cost of increasing the time for
creating the data structure.


title: Environment-Assisted Quantum Transport

abstract:
  Transport phenomena at the nanoscale are of interest due to the presence of
both quantum and classical behavior. In this work, we demonstrate that quantum
transport efficiency can be enhanced by a dynamical interplay of the system
Hamiltonian with pure dephasing induced by a fluctuating environment. This is
in contrast to fully coherent hopping that leads to localization in disordered
systems, and to highly incoherent transfer that is eventually suppressed by the
quantum Zeno effect. We study these phenomena in the Fenna-Matthews-Olson
protein complex as a prototype for larger photosynthetic energy transfer
systems. We also show that disordered binary tree structures exhibit enhanced
transport in the presence of dephasing.


title: Probing feedback in protogalaxies: Multiphase gas in a DLA at z~2.4

abstract:
  We investigate the physical processes occuring in the multiphase gas of a
damped Ly\alpha system (DLA). We base our analysis on a high quality Keck HIRES
spectrum of the QSO J1211+0422 in which a DLA is detected at z=2.377. There is
little contamination of the high-ion (OVI, NV, CIV, SiIV) absorption, allowing
us to explore the properties of the highly ionized gas and its connection to
other gas-phases. The metallicity ([Z/H]=-1.41+/-0.08), HI column density (log
N(HI)=20.80+/-0.10), full-width velocity (\Delta(v_ neut)=70 km/s) and relative
abundances ([Si/Fe]=+0.23+/-0.05 and [N/Si]=-0.88+/-0.07) of this DLA are not
unusual. However, we derive the lowest CII* cooling rate in a DLA, l_c <
10^{-27.8} erg/s per H atom (3\sigma). Using this stringent limit, we show that
the neutral gas (confined at |v|<+39 km/s) must be warm and the star formation
rate is <7.1x10^{-3} M_odot/yr/kpc^2. Surprisingly, the gas shows strong,
complex absorption profiles from highly ionized gas whose kinematics appear
connected to each other and the low ions. The total amount of highly and weakly
ionized gas is very large with N(HII)/N(HI)>1.5. At |v|>+39 km/s, the gas is
fully and highly ionized (H+/H~1, N(CIV)>>N(CII), N(SiIV)>>N(SiII)). Based on
ionization models, OVI and NV are generally difficult to produce by hard
photons, while SiIV and CIV can be photoionized to a large extent. There is,
however, no evidence of OVI-bearing gas at T~10^6 K associated with this DLA.
In contrast, there is some evidence for narrow OVI, NV, and CIV components
(unexplained by photoionization), implying too low temperatures (T < 10^5 K)
for simple collisional ionization models to produce their observed column
densities. Stellar feedback is a possible source for producing the high ions,
but we cannot rule out accretion of non-pristine material onto the protogalaxy.


title: Theory of Raman transitions in cavity QED

abstract:
  We present two schemes for driving Raman transitions between the ground state
hyperfine manifolds of a single atom trapped within a high-finesse optical
cavity. In both schemes, the Raman coupling is generated by standing-wave
fields inside the cavity, thus circumventing the optical access limitations
that free-space Raman schemes must face in a cavity system. These cavity-based
Raman schemes can be used to coherently manipulate both the internal and the
motional degrees of freedom of the atom, and thus provide powerful tools for
studying cavity quantum electrodynamics. We give a detailed theoretical
analysis of each scheme, both for a three-level atom and for a multi-level
cesium atom. In addition, we show how these Raman schemes can be used to cool
the axial motion of the atom to the quantum ground state, and we perform
computer simulations of the cooling process.


title: Solving the Inverse Problem with Inhomogeneous Universes

abstract:
  We construct the Lema\^itre-Tolman-Bondi (LTB) dust universe whose
distance-redshift relation is equivalent to that in the concordance $\Lambda$
cold dark matter ($\Lambda$CDM) cosmological model. In our model, the density
distribution and velocity field are not homogeneous, whereas the big-bang time
is uniform, which implies that the universe is homogeneous at its beginning. We
also study the effects of local clumpiness in the density distribution as well
as the effects of large-scale inhomogeneities on the distance-redshift
relation, and show that these effects may reduce the amplitude of large-scale
inhomogeneities necessary for having a distance-redshift relation that is the
same as that of the concordance $\Lambda$CDM universe. We also study the
temporal variation of the cosmological redshift and show that, by the
observation of this quantity, we can distinguish our LTB universe model from
the concordance $\Lambda$CDM model, even if their redshift-distance relations
are equivalent to each other.


title: On the number of minimal surfaces with a given boundary

abstract:
  We generalize the following result of White: Suppose $N$ is a compact,
strictly convex domain in $\RR^3$ with smooth boundary. Let $\Sigma$ be a
compact 2-manifold with boundary. Then a generic smooth curve $\Gamma\cong
\partial\Sigma$ in $\partial N$ bounds an odd or even number of embedded
minimal surfaces diffeomorphic to $\Sigma$ according to whether $\Sigma$ is or
is not a union of disks. First, we prove that the parity theorem holds for any
compact riemannian 3-manifold $N$ such that $N$ is strictly mean convex, $N$ is
homeomorphic to a ball, $\partial N$ is smooth, and $N$ contains no closed
minimal surfaces. We then further relax the hypotheses by allowing $N$ to be
weakly mean convex and to have piecewise smooth boundary. We extend the parity
theorem yet further by showing that, under an additional hypothesis, it remains
true for minimal surfaces with prescribed symmetries.
  The parity theorems are used in an essential way to prove the existence of
embedded genus-$g$ helicoids in $\SS^2\times \RR$. We give a very brief outline
of this application. (The full argument will appear elsewhere.)


title: Particle Acceleration at Interplanetary Shocks

abstract:
  The acceleration of interstellar pick-up ions as well as solar wind species
has been observed at a multitude of interplanetary (IP) shocks by different
spacecraft. This paper expands upon previous work modeling the phase space
distributions of accelerated ions associated with the shock event encountered
on day 292 of 1991 by the Ulysses mission at 4.5 AU. A kinetic Monte Carlo
simulation is employed here to model the diffusive acceleration process. This
exposition presents recent developments pertaining to the incorporation into
the simulation of the diffusive characteristics incurred by field line
wandering (FLW), according to the work of Giacalone and Jokipii. For a pure
field-line wandering construct, it is determined that the upstream spatial ramp
scales are too short to accommodate the HI-SCALE flux increases for 200 keV
protons, and that the distribution function for H+ somewhat underpopulates the
combined SWICS/HI-SCALE spectra at the shock. This contrasts our earlier
theory/data comparison where it was demonstrated that diffusive transport in
highly turbulent fields according to kinetic theory can successfully account
for both the proton distributions and upstream ramp scales, using a single
turbulence parameter. The principal conclusion here is that, in a FLW scenario,
the transport of ions across the mean magnetic field is slightly less efficient
than is required to effectively trap energetic ions within a few Larmor radii
of the shock layer and thereby precipitate efficient acceleration. This
highlights the contrast between ion transport in highly turbulent shock
environs and remote, less-disturbed interplanetary regions.


title:
Spectrophotometric properties of pre-main sequence stars: the Epsilon
  Chamaeleontis cluster

abstract:
  We present a study of flux-calibrated low-resolution optical spectroscopy of
ten stars belonging to eight systems in the ~ 5 Myr-old Epsilon Chamaeleontis
(Eps Cha) pre-main-sequence (PMS) star cluster. Using synthetic broadband
colours, narrow-band continuum, atomic and molecular lines derived from the
spectra, we compare the Eps Cha stars to a slightly older PMS cluster, the ~ 8
Myr-old Eta Cha cluster, and to main-sequence dwarfs. Using synthetic VRI
colours and other indices, we find that the relationship between broadband
colours and spectroscopic temperature indicators for Eps Cha cluster members is
indistinguishable from that of Gyr-old dwarfs. This result is identical to that
found earlier in Eta Cha. Gravity-sensitive line indices place the cluster
between the giant and dwarf sequences, and there is clear evidence that Eps Cha
stars have lower surface gravity than Eta Cha stars. This result is consistent
with Eps Cha being the slightly younger PMS association, a few Myr younger
according to the Hertzsprung-Russell (HR) diagram placement of these two
clusters and comparison with PMS evolutionary grids. Late M-type Eps Cha
cluster members show a B-band flux excess of ~ 0.2 mag compared to observations
of standard dwarfs, which might be related to enhanced magnetic activity. A
similar level of excess B-band emission appears to be a ubiquitous feature of
low mass members of young stellar populations with ages less than a few hundred
Myr, a very similar timescale to the PMS phase of elevated relative X-ray
luminosity.


title:
On pseudo-Riemannian Lie algebras: a class of new Lie-admissible
  algebras

abstract:
  M. Boucetta introduced the notion of pseudo-Riemannian Lie algebra in [2]
when he studied the line Poisson structure on the dual of a Lie algebra. In
this paper, we redefine pseudo-Riemannian Lie algebra, which, in essence, is a
class of new Lie admissible algebras and prove that all pseudo-Riemannian Lie
algebras are solvable. Using our main result and method, we prove some of M.
Boucetta's results in [2, 3] in a simple and new way, then we give an explicit
construction of Riemann-Lie algebras and a classification of pseudo-Riemannian
Lie algebras of dimension 2 and 3.


title:
Breakdown of Lorentz Invariance for Spin-1/2 Particle Motion in Curved
  Space-Time with Applications to Muon Decay

abstract:
  This paper explores the properties of the Pauli-Lubanski spin vector for the
general motion of spin-1/2 particles in curved space-time. Building upon
previously determined results in flat space-time, it is shown that the
associated Casimir scalar for spin possesses both gravitational contributions
and frame-dependent contributions due to non-inertial motion, where the latter
represents a possible quantum violation of Lorentz invariance that becomes
significant at the Compton wavelength scale. When applied to muon decay near
the event horizon of a microscopic Kerr black hole, it is shown that its
differential cross section is strongly affected by curvature, with particular
sensitivity to changes in the black hole's spin angular momentum. In the
absence of curvature, the non-inertial contributions to the decay spectrum are
also identified and explored in detail, where its potential for observation is
highest for large electron opening angles. It is further shown how possible
contributions to noncommutative geometry can emerge from within this formalism
at some undetermined length scale. Surprisingly, while the potential exists to
identify noncommutative effects in muon decay, the relevant terms make no
contribution to the decay spectrum, for reasons which remain unknown.


title: Dilute Hard "Sphere" Bose Gas in Dimensions 2, 4 and 5

abstract:
  The ground state energy for a dilute hard "sphere" Bose gas in various
dimensions is studied theoretically.


title: On $G$--modular functor

abstract:
  In this paper, we extend the notion of modular functor and fusion category to
what we called $G$ equivariant modular functor and $G$ equivariant fusion
category, where $G$ is a finite group, and establish a correspondence between
between these notions.


title:
Ultraviolet Survey of CO and H_2 in Diffuse Molecular Clouds: The
  Reflection of Two Photochemistry Regimes in Abundance Relationships

abstract:
  (Abridged) We carried out a comprehensive far-ultraviolet (UV) survey of
^12CO and H_2 column densities along diffuse molecular Galactic sight lines in
order to explore in detail the relationship between CO and H_2. We measured new
CO abundances from HST spectra, new H_2 abundances from FUSE data, and new CH,
CH^+, and CN abundances from the McDonald and European Southern Observatories.
A plot of log N(CO) versus log N(H_2) shows that two power-law relationships
are needed for a good fit of the entire sample, with a break located at log
N(CO, cm^-2) = 14.1 and log N(H_2) = 20.4, corresponding to a change in
production route for CO in higher-density gas. Similar logarithmic plots among
all five diatomic molecules allow us to probe their relationships, revealing
additional examples of dual slopes in the cases of CO versus CH (break at log N
= 14.1, 13.0), CH^+ versus H_2 (13.1, 20.3), and CH^+ versus CO (13.2, 14.1).
These breaks are all in excellent agreement with each other, confirming the
break in the CO versus H_2 relationship, as well as the one-to-one
correspondence between CH and H_2 abundances. Our new sight lines were selected
according to detectable amounts of CO in their spectra and they provide
information on both lower-density (< 100 cm^-3) and higher-density diffuse
clouds. The CO versus H_2 correlation and its intrinsic width are shown to be
empirically related to the changing total gas density among the sight lines of
the sample. We employ both analytical and numerical chemical schemes in order
to derive details of the molecular environments. In the low-density gas, where
equilibrium-chemistry studies have failed to reproduce the abundance of CH^+,
our numerical analysis shows that nonequilibrium chemistry must be employed for
correctly predicting the abundances of both CH^+ and CO.


title: A point source survey of M31 with the Spitzer Space Telescope

abstract:
  We explore the stellar population of M31 in a Spitzer Space Telescope survey
utilizing IRAC and MIPS observations. Red supergiants are the brightest objects
seen in the infrared; they are a prominent evolutionary phase. Due to their
circumstellar envelopes, many of these radiate the bulk of their luminosity at
IRAC wavelengths and do not stand out in the near infrared or optically. Going
fainter, we see large numbers of luminous asymptotic giant branch (AGB) stars,
many of which are known long period variables. Relative to M33, the AGB carbon
star population of M31 appears sparse, but this needs to be spectroscopically
confirmed.


title: Secrecy via Sources and Channels

abstract:
  Alice and Bob want to share a secret key and to communicate an independent
message, both of which they desire to be kept secret from an eavesdropper Eve.
We study this problem of secret communication and secret key generation when
two resources are available -- correlated sources at Alice, Bob, and Eve, and a
noisy broadcast channel from Alice to Bob and Eve which is independent of the
sources. We are interested in characterizing the fundamental trade-off between
the rates of the secret message and secret key. We present an achievable
solution and prove its optimality for the parallel channels and sources case
when each sub-channel and source component satisfies a degradation order
(either in favor of the legitimate receiver or the eavesdropper). This includes
the case of jointly Gaussian sources and an additive Gaussian channel, for
which the secrecy region is evaluated.


title: Quantizations of Character Varieties and Quantum Knot Invariants

abstract:
  Let G be a simple complex algebraic group and g its Lie algebra. We show that
the g-Witten-Reshetikhin-Turaev quantum invariants determine a
deformation-quantization, C_q[X_G(torus)], of the coordinate ring of the
G-character variety of the torus. We prove that this deformation is in the
direction of the Goldman's bracket. Furthermore, we show that every knot K
defines an ideal I_K in C_q[X_G(torus)]. We conjecture that the homomorphism
C_q[X_G(torus)] -> C[X_G(torus)], q -> 1, maps I_K to the ideal whose radical
is the kernel of the map C[X_G(torus)] -> C[X_G(S^3 K)]. This conjecture is
related to AJ-conjecture for sl(2,\C). The results of this paper are inspired
by the theory of q-holonomic relations between quantum invariants of
Garoufalidis and Le. Along the way, we disprove Conjecture 2 in Le's "The
Colored Jones and the A-polynomial of Two-Bridge knots".


title: Strange magnetic form factor of the proton at $Q^2 = 0.23$ GeV$^2$

abstract:
  We determine the $u$ and $d$ quark contributions to the proton magnetic form
factor at finite momentum transfer by applying chiral corrections to quenched
lattice data. Heavy baryon chiral perturbation theory is applied at next to
leading order in the quenched, and full QCD cases for the valence sector using
finite range regularization. Under the assumption of charge symmetry these
values can be combined with the experimental values of the proton and neutron
magnetic form factors to deduce a relatively accurate value for the strange
magnetic form factor at $Q^2=0.23$ GeV$^2$, namely $G_M^s=-0.034 \pm 0.021$
$\mu_N$.


title: Generalised scalar-tensor theory and the cosmic acceleration

abstract:
  In this paper it has been shown that a simple functional form of
$\omega(\phi)$ in a generalised scalar tensor theory can drive the present
cosmic acceleration without any quintessence field or the cosmological constant
$\Lambda$. Furthermore, it ensures a smooth transition from a decelerated to an
accelerated phase of expansion in the matter dominated regime.


title:
Synthesis, Contact Printing, and Device Characterization of
  Ni-Catalyzed, Crystalline InAs Nanowires

abstract:
  InAs nanowires have been actively explored as the channel material for high
performance transistors owing to their high electron mobility and ease of ohmic
metal contact formation. The catalytic growth of non-epitaxial InAs nanowires,
however, has often relied on the use of Au colloids which is non-CMOS
compatible. Here, we demonstrate the successful synthesis of high yield of
crystalline InAs nanowires with high yield and tunable diameters by using Ni
nanoparticles as the catalyst material on amorphous SiO2 substrates. The
nanowires show superb electrical properties with field-effect electron mobility
~2,700 cm2/Vs and ION/IOFF >103. The uniformity and purity of the grown InAs
nanowires are further demonstrated by large-scale assembly of parallel arrays
of nanowires on substrates via the contact printing process that enables high
performance, printable transistors, capable of delivering 5-10 mA ON currents
(~400 nanowires).


title: Limiting Nature of Continuum Generation in Silicon

abstract:
  Spectral broadening in silicon is studied numerically as well as
experimentally. Temporal dynamics of the free carriers generated during the
propagation of optical pulses, through the process of two-photon absorption
(TPA), affect the amplitude and phase of the optical pulses, thereby
determining the nature and extent of the generated spectral continuum.
Experimental results are obtained by propagating pico-second optical pulses in
a silicon waveguide for intensities that span two orders of magnitude (1-150
GW/cm2). These results validate the conclusions drawn from numerical
simulations that the continuum generation has a self-limiting nature in
silicon.


title:
Successive phase transitions at finite temperatures of the supersolid in
  the three-dimensional extended Bose-Hubbard model

abstract:
  We study the finite temperature properties of the extended Bose-Hubbard model
on a cubic lattice. This model exhibits the so-called supersolid state. To
start with, we investigate ordering processes by quantum Monte Carlo
simulations, and find successive superfluid and solid phase transitions. There,
we find that the two order parameters compete with each other. We obtain the
finite temperature phase diagram, which contains the superfluid, the solid, the
supersolid and the disordered phase. We develop a mean-field theory to analyze
the ordering processes and compare the result with that obtained by
simulations, and discuss the mechanism of the competition of these two orders.
We also study how the supersolid region shrinks as the on-site repulsion
becomes strong.


title: Helix or Coil? Fate of a Melting Heteropolymer

abstract:
  We determine the probability that a partially melted heteropolymer at the
melting temperature will either melt completely or return to a helix state.
This system is equivalent to the splitting probability for a diffusing particle
on a finite interval that moves according to the Sinai model. When the initial
fraction of melted polymer is f, the melting probability fluctuates between
different realizations of monomer sequences on the polymer. For a fixed value
of f, the melting probability distribution changes from unimodal to a bimodal
as the strength of the disorder is increased.


title: Transition to turbulence through decline of viscosity

abstract:
  Experiments (Mullin and Kreswell, 2005) show that transition to turbulence
can start at Reynolds numbers lower than it is predicted by the linear
stability analysis - the subcritical transition to turbulence. To explain these
observations qualitatively we suggest that the onset of subcritical instability
is related to decline of viscosity of the fluid: friction between fluid layers
fails with the increase of the velocity gradient. To describe the declinie of
friction theoretically we relax the the assumption of the stability of the
fluid material and introduce a constant of fluid strength. Particularly, we
enhance the Navier-Stokes model with a failure description by introducing the
fluid strength in the constitutive equation for the viscous stress. The
clasical model is obtained from the enhanced one when strength goes to
infinity. We use the modified Navier-Stokes model to analyze the Couette flow
between two parallel plates and find that the lateral perturbations can
destabilize the flow and the critical Reynolds number is proportional to the
fluid strength. The latter means that the classical Navier-Stokes model of a
stable material with infinite strength does not capture the subcritical
transition to turbulence while the mofified model does.


title: Prompt High-Energy Emission from Proton-Dominated Gamma-Ray Bursts

abstract:
  The prompt emission of gamma-ray bursts (GRBs) is widely thought to be
radiation from accelerated electrons, but an appreciably larger amount of
energy could be carried by accelerated protons, particularly if GRBs are the
sources of ultra-high-energy cosmic rays (UHECRs). We model the expected photon
spectra for such "proton-dominated" GRBs in the internal shock scenario through
Monte Carlo simulations, accounting for various processes related to
high-energy electrons and protons. Besides proton and muon synchrotron
components, emission from photomeson-induced secondary pair cascades becomes
crucial, generally enhancing the GeV-TeV and/or eV-keV photons and offering a
signature of UHE protons. In some cases, it can overwhelm the primary electron
component and result in GRBs peaking in the 10 MeV - 1 GeV range, which may be
relevant to some bursts discussed in a recent re-analysis of EGRET TASC data.
The dependence of the spectra on key quantities such as the bulk Lorentz
factor, magnetic field and proton-to-electron ratio is nontrivial due to the
nonlinear nature of cascading and the interplay of electron- and proton-induced
components. Observations by {\it Fermi}, ground-based telescopes and other
facilities should test these expectations and provide critical constraints on
the proton acceleration efficiency.


title:
Similarities between neutrinos and Higgs bosons within a chiral
  supersymmetric formulation

abstract:
  Taking into account the helicity of a massless particle, which obeys a Dirac
equation and is exposed to an electromagnetic field, one soon arrives at a
Lagrangian containing a chiral supersymmetric operator. We can even achieve an
analogous result in case of an electroweak interaction. Then the Lagrangian
contains terms that look very similar to those usually being interpreted as
mass terms for the W and Z bosons appearing in models of spontaneous symmetry
breaking, but this time they are accompanied by neutrino fields instead of
Higgs fields. This invites us to a speculation that in the procedure of
spontaneous symmetry breaking, neutrinos could take on the role, which we
normally ascribe to the Higgs bosons.


title:
On the interaction of the electromagnetic radiation with the breaking
  plasma waves

abstract:
  An electromagnetic wave (EMW) interacting with the moving singularity of the
charged particle flux undergoes the reflection and absorption as well as
frequency change due to Doppler effect and nonlinearity. The singularity
corresponding to a caustic in plasma flow with inhomogeneous velocity can arise
during the breaking of the finite amplitude Langmuir waves due to nonlinear
effects. A systematic analysis of the wave-breaking regimes and caustics
formation is presented and the EMW reflection coefficients are calculated.


title:
Signature of short distance physics on inflation power spectrum and CMB
  anisotropy

abstract:
  The inflaton field responsible for inflation may not be a canonical
fundamental scalar. It is possible that the inflaton is a composite of fermions
or it may have a decay width. In these cases the standard procedure for
calculating the power spectrum is not applicable and a new formalism needs to
be developed to determine the effect of short range interactions of the
inflaton on the power spectrum and the CMB anisotropy. We develop a general
formalism for computing the power spectrum of curvature perturbations for such
non-canonical cases by using the flat space K\"all\'en-Lehmann spectral
function in curved quasi-de Sitter space assuming implicitly that the
Bunch-Davis boundary conditions enforces the inflaton mode functions to be
plane wave in the short wavelength limit and a complete set of mode functions
exists in quasi-de Sitter space. It is observed that the inflaton with a decay
width suppresses the power at large scale while a composite inflaton's power
spectrum oscillates at large scales. These observations may be vindicated in
the WMAP data and confirmed by future observations with PLANCK.


title: Wigner islands with electrons over helium

abstract:
  We present here the first experimental study of Wigner islands formed by
electrons floating over helium. Electrons are trapped electrostatically in a
mesoscopic structure covered with a helium film, behaving as a quantum dot. By
removing electrons one by one, we are able to find the addition spectrum, i.e.
the energy required to add (or extract) one electron from the trap with
occupation number $N$. Experimental addition spectra are compared with Monte
Carlo simulations for the actual trap geometry, confirming the ordered state of
electrons over helium in the island.


title: Componentwise condition numbers of random sparse matrices

abstract:
  We prove an O(log n) bound for the expected value of the logarithm of the
componentwise (and, a fortiori, the mixed) condition number of a random sparse
n x n matrix. As a consequence, small bounds on the average loss of accuracy
for triangular linear systems follow.


title: Faster than light communication : is it possible ?

abstract:
  A quantum optical apparatus permitting a faster than light communication
between distant locations has been recently proposed by Shiekh. Some several
conceptual difficulties concerning this proposal are briefly addressed.


title: Cosmological consequences of generalised RS II braneworlds

abstract:
  We discuss certain features of cosmology in a generalised RS II braneworld
scenario. In this scenario, the bulk is given by a Schwarzschild-anti de Sitter
or a Vaidya-anti de Sitter black hole in which an FRW brane is consistently
embedded, resulting in modifications of the 4-dimensional Friedmann equations.
We analyse how the scenario can be visualised and discuss the significance of
each term in these modified equations both for early time and for late time
cosmology. We further analyse the perturbation equations, based on Newtonian as
well as relativistic perturbations and show that the scenario has the
potentiality to explain structure formation by the ``Weyl fluid'' arising from
embedding geometry. The results thus obtained are confronted with observations
as well.


title: Corrected entropy of BTZ black hole in tunneling approach

abstract:
  We investigate further the recent analysis \cite{R.Banerjee2}, based on a
Hamilton-Jacobi type approach, to compute the temperature and entropy of black
holes beyond the semiclassical approximation. It is shown how non spherically
symmetric geometries are inducted in the general formalism by explicitly
considering the BTZ black hole. The leading (logarithmic) and non leading
corrections to the area law are obtained.


title: Spherically Symmetric Noncommutative Space: d = 4

abstract:
  In order to find a noncommutative analog of Schwarzschild or
Schhwarzschild-de Sitter blackhole we investigate spherically symmetric spaces
generated by four noncommutative coordinates in the frame formalism. We present
two solutions which however do not posess the prescribed commutative limit. Our
analysis indicates that the appropriate noncommutative space might be found as
a subspace of a higher-dimensional space.


title:
Shape of primary proton spectrum in multi-TeV region from data on
  vertical muon flux

abstract:
  It is shown, that primary proton spectrum, reconstructed from sea-level and
underground data on muon spectrum with the use of QGSJET 01, QGSJET II, NEXUS
3.97 and SIBYLL 2.1 interaction models, demonstrates not only model-dependent
intensity, but also model-dependent form. For correct reproduction of muon
spectrum shape primary proton flux should have non-constant power index for all
considered models, except SIBYLL 2.1, with break at energies around 10-15 TeV
and value of exponent before break close to that obtained in ATIC-2 experiment.
To validate presence of this break understanding of inclusive spectra behavior
in fragmentation region in p-air collisions should be improved, but we show,
that it is impossible to do on the basis of the existing experimental data on
primary nuclei, atmospheric muon and hadron fluxes.


title:
Van der Waals Frictional Drag induced by Liquid Flow in Low- Dimensional
  Systems

abstract:
  We study the van der Waals frictional drag force induced by liquid flow in
low-dimensional systems (2D and 1D electron systems, and 2D and 1D channels
with liquid). We find that for both 1D and 2D systems, the frictional drag
force induced by liquid flow may be several orders of magnitude larger than the
frictional drag induced by electronic current.


title: The Ratio of sigma_L(W2, Q2)/sigma_T(W2, Q2) in the Color Dipole Picture

abstract:
  The transverse size of q q-bar fluctuations of the longitudinal photon is
reduced relative to the transverse size of q q-bar fluctuations of the
transverse photon. This implies R(W^2, Q^2) = 0.375 or, equivalently,
F_L(W^2,Q^2)/F_2(W^2,Q^2) = 0.27 for x = Q^2/W^2 << 1 and Q^2 sufficiently
large, while R(W^2, Q^2) = 0.5, if this effect is not taken into account.
Forthcoming experimental data from HERA will allow to test this prediction.


title: Traffic by small teams of molecular motors

abstract:
  Molecular motors transport various cargos along cytoskeletal filaments,
analogous to trucks on roads. In contrast to vehicles, however, molecular
motors do not work alone but in small teams. We describe a simple model for the
transport of a cargo by one team of motors and by two teams of motors, which
walk into opposite directions. The cooperation of one team of motors generates
long-range transport, which we observed experimentally in vitro. Transport by
two teams of motors leads to a variety of bidirectional motility behaviour and
to dynamic instabilities reminiscent of spontaneous symmetry breaking. We also
discuss how cargo transport by teams of motors allows the cell to generate
robust long-range bidirectional transport.


title:
Using squeezed field to preserve two-atom entanglement against
  spontaneous emissions

abstract:
  Tunable interaction between two atoms in a cavity is realized by interacting
the two atoms with an extra controllable single-mode squeezed field. Such a
controllable interaction can be further used to control entanglement between
the two atoms against amplitude damping decoherence caused by spontaneous
emissions. For the independent amplitude damping decoherence channel,
entanglement will be lost completely without controls, while it can be
partially preserved by the proposed strategy. For the collective amplitude
damping decoherence channel, our strategy can enhance the entanglement compared
with the uncontrolled case when the entanglement of the uncontrolled stationary
state is not too large.


title: On the mathematical representation of nonlinearity

abstract:
  The suggestion of writing, for some problems, nonlinear state equations not
as dx/dt = F(x,u,t), but as dx/dt = [A(t,x)]x + [B(t,x)]u(t), which is more
"constructive", is considered supported by arguments related to: the
axiomatization of system theory, the classification of switched circuits as
linear and nonlinear, the use of nonlinear sampling for measuring frequency
without clock, the consideration of an ensemble of colliding particles in which
the establishing of the chaotic movements is seen as a result of the same kind
of nonlinearity as in electronic switching circuits, the modeling of a liquid
medium as a "system" whose structure is directly influenced by the "input", and
some other problems.


title: Astrophysics in S.Co.P.E

abstract:
  S.Co.P.E. is one of the four projects funded by the Italian Government in
order to provide Southern Italy with a distributed computing infrastructure for
fundamental science. Beside being aimed at building the infrastructure,
S.Co.P.E. is also actively pursuing research in several areas among which
astrophysics and observational cosmology. We shortly summarize the most
significant results obtained in the first two years of the project and related
to the development of middleware and Data Mining tools for the Virtual
Observatory.


title: Hole - Nuclear Spin Interaction in Quantum Dots

abstract:
  We have measured the carrier spin dynamics in p-doped InAs/GaAs quantum dots
by pump-probe photo-induced circular dichroism and time-resolved
photoluminescence experiments. We show that the hole spin dephasing is
controlled by the hyperfine interaction between hole and nuclear spins. In the
absence of external magnetic field, we find a characteristic hole spin
dephasing time of 15 ns, in close agreement with our calculations based on
dipole-dipole coupling between the hole and the quantum dot nuclei. Finally we
demonstrate that a small external magnetic field, typically 10 mT instead of
200 mT for the case of electrons, quenches the hyperfine hole spin dephasing.


title: A model for the motion of a particle in a quantum background

abstract:
  We are studying the dynamics of a one-dimensional field in a non-commutative
Euclidean space. The non-commutative space we consider is the one that emerges
in the context of three dimensional Euclidean quantum gravity: it is a
deformation of the classical Euclidean space and the Planck length plays the
role of the deformation parameter. The field is interpreted as a particle which
evolves in a quantum background. When the dynamics of the particle is linear,
the resulting motion is similar to the standard motion in the classical space.
However, non-linear dynamics on the non-commutative space are different from
the corresponding non-linear dynamics on the classical space. These
discrepencies are interpreted as "quantum gravity" effects. Finally, we propose
a background independent description of the propagation of the particle in the
quantum geometry.


title: Poincar\'e recurrence for observations

abstract:
  A high dimensional dynamical system is often studied by experimentalists
through the measurement of a relatively low number of different quantities,
called an observation. Following this idea and in the continuity of
Boshernitzan's work, for a measure preserving system, we study Poincar\'e
recurrence for the observation. The link between the return time for the
observation and the Hausdorff dimension of the image of the invariant measure
is considered. We prove that when the decay of correlations is super
polynomial, the recurrence rates for the observations and the pointwise
dimensions relatively to the push-forward are equal.


title:
The delayed contribution of low and intermediate mass stars to chemical
  galactic enrichment: An analytical approach

abstract:
  We find a new analytical solution for the chemical evolution equations,
taking into account the delayed contribution of all low and intermediate mass
stars (LIMS) as one representative star that enriches the interstellar
medium.This solution is built only for star formation rate proportional to the
gas mass in a closed box model. We obtain increasing C/O and N/O ratios with
increasing O/H, behavior impossible to match with the Instantaneous Recycling
Approximation (IRA). Our results, obtained by two analytical equations, are
very similar to those found by numerical models that consider the lifetimes of
each star. This delayed model reproduces successfully the evolution of C/O-O/H
and Y-O relations in the solar vicinity. This analytical approximation is a
useful tool to study the chemical evolution of elements produced by LIMS when a
galactic chemical evolutionary code is not available.


title:
Canonical representation for electrons and its application to the
  Hubbard model

abstract:
  A new representation for electrons is introduced, in which the electron
operators are written in terms of a spinless fermion and the Pauli operators.
This representation is canonical, invertible and constraint-free. Importantly,
it simplifies the Hubbard interaction. On a bipartite lattice, the Hubbard
model is reduced to a form in which the exchange interaction emerges simply by
decoupling the Pauli subsystem from the spinless fermion bath. This exchange
correctly reproduces the large $U$ superexchange. Also derived, for
$U=\pm\infty$, is the Hamiltonian to study Nagaoka ferromagnetism. In this
representation, the infinite-$U$ Hubbard problem becomes elegant and easier to
handle. Interestingly, the ferromagnetism in Hubbard model is found to be
related to the gauge invariance of the spinless fermions. Generalization of
this representation for the multicomponent fermions, a new representation for
bosons, the notion of a `soft-core' fermion, and some interesting unitary
transformations are introduced and discussed in the appendices.


title: An end-to-end-construction for singly periodic minimal surfaces

abstract:
  We show the existence of various families of properly embedded singly
periodic minimal surfaces in R^3 with finite arbitrary genus and Scherk type
ends in the quotient. The proof of our results is based on the gluing of small
perturbations of pieces of already known minimal surfaces.


title: On automorphism groups of some types of generic distributions

abstract:
  To certain types of generic distributions (subbundles in a tangent bundle)
one can associate canonical Cartan connections. Many of these constructions
fall into the class of parabolic geometries. The aim of this article is to show
how strong restrictions on the possibles sizes of automorphism groups of such
distributions can be deduced from the existence of canonical Cartan
connections. This needs no information on how the Cartan connections are
actually constructed and only very basic information on their properties. In
particular, we discuss the examples of generic distributions of rank two in
dimension five, rank three in dimension six, and rank four in dimension seven.


title: Long-Lived Unstable Superparticles at the LHC

abstract:
  In various models of supersymmetry (SUSY), the lightest superparticle in the
minimal SUSY standard model sector, which we call MSSM-LSP, becomes unstable.
Then, we may observe the decay of the MSSM-LSP in the detector at the LHC
experiment. We show that the discovery of such a decay process (and the
determination of the lifetime of the MSSM-LSP) may be possible at the LHC even
if the decay length of the MSSM-LSP is much longer than the size of the
detector; sizable number of the MSSM-LSPs decay inside the detector if the
lifetime is shorter than 0.01-1 millisec. We also discuss the implications of
the study of the MSSM-LSP decay for several well-motivated SUSY models.


title: Massive particle production to NNLO in QCD

abstract:
  We discuss the recent derivation of the one-loop squared virtual QCD
corrections to the W boson pair production in the quark-anti-quark-annihilation
channel in the limit where all kinematical invariants are large compared to the
mass of the W boson. In particular, we elaborate on the combined use of the
helicity matrix formalism with the Mellin-Barnes representations technique.


title: Chern-Simons gravity, based on a non-semisimple group

abstract:
  The gauge theory-formulation of string-motivated lineal gravity proposed by
Cangemi and Jackiw is obtained by dimensional reduction from $(2+1)$
dimensional gravity with a Chern-Simons Lagrangian.


title: Emergent Radiation in an Atom-Field System at Twice-Resonance

abstract:
  A two-level atom interacting with a single mode of quantized electromagnetic
radiation is discussed using a representation in which the atom and the
radiation are unified into a {\em new} canonical radiation. At the {\em
twice-resonance}, when the frequency of the original radiation is twice the
atomic transition frequency ($\omega=2\epsilon$), the {\em emergent} unified
field in the non-interacting atom-field system resembles a free radiation of
frequency $\epsilon$. This free emergent radiation is further shown to exist in
the presence of an interaction which looks similar to the atom-field
interaction in the dipole approximation. The one-photon correlation and the
population inversion are discussed as the possible means of observing the
emergent radiation. The entanglement properties of the emergent radiation are
also discussed.


title: On different notions of tameness in arithmetic geometry

abstract:
  The notion of a tamely ramified covering is canonical only for curves.
Several notions of tameness for coverings of higher dimensional schemes have
been used in the literature. We show that all these definitions are essentially
equivalent. Furthermore, we prove finiteness theorems for the tame fundamental
groups of arithmetic schemes.


title:
Stochastic polarization formation in exciton-polariton Bose-Einstein
  condensates

abstract:
  We demonstrate theoretically the spontaneous formation of a stochastic
polarization in exciton-polariton Bose-Einstein condensates in planar
microcavities under pulsed excitation. Below the threshold pumping intensity
(dependent on the polariton life-time) the average polarization degree is close
to zero, whilst above threshold the condensate acquires a polarization
described by a (pseudospin) vector with random orientation, in general. We
establish the link between second order coherence of the polariton condensate
and the distribution function of its polarization. We examine also the
mechanisms of polarization dephasing and relaxation.


title: Doubly Coexisting Dark Matter Candidates in an Extended Seesaw Model

abstract:
  We examine how a scenario of coexisting two-particle dark mater can be
realized in the extended seesaw model, which we have proposed previously to
accommodate small neutrino masses and low scale leptogenesis with an
introduction of singlet Majorana neutrino $S$ and singlet scalar $\phi$. We now
impose the discrete symmetry $Z_2 \times Z_2^{\prime}$ and introduce new
renormalizable interaction terms with a new heavy singlet scalar particle
$\Phi$ so as for previously introduced $S$ and $\phi$ to be doubly coexisting
dark matter candidates. Depending on the mass spectrum of the two dark matter
candidates, the annihilation process either $SS\longrightarrow \phi \phi$ or
$\phi\phi\longrightarrow SS$ is of particular interest because the annihilation
cross sections for the processes can be so large that the relic abundance of
decaying particle should get lowered, which in turn makes the constraints on
its parameter space relaxed, compared with the case of one and only one dark
matter candidate. We discuss the implications of the dark matter detection
through the scattering off the nucleus of the detecting material on our
scenarios for dark matter candidates. We also study the implications for the
search of invisible Higgs decay at LHC, which may serve as a probe of our
scenario for dark matter.


title: Varieties with generically nef tangent bundles

abstract:
  We study the geometry of projective manifolds whose tangent bundles are nef
on sufficiently general curves (i.e. the tangent bundle is generically nef) and
show that manifolds whose anticanonical bundles are semi-ample have this
property. Furthermore we introduce a notion of sufficient nefness and
investigate the relation with manifolds whose anticanonical bundles are nef.


title: Optical Observations of PSR J0205+6449

abstract:
  PSR J0205+6449 is a X-ray and radio pulsar in supernova remnant 3C 58. We
report on observations of the central region of 3C 58 using the 4.2-m William
Herschel Telescope with the intention of identifying the optical counterpart of
PSR J0205+6449 and characterising its pulsar wind nebula.
  Around the pulsar position we identified extended emission with a magnitude
of $B = 23 \fm 97 \pm 0.10$, $V = 22 \fm 95 \pm 0.05$ and $R = 22 \fm 15 \pm
0.03$ consistent with a pulsar wind nebula. From the R-band image we identified
three knots with $m_R$ = $24 \fm 08 \pm 0.07$ (o1), $24 \fm 15 \pm 0.07$ (o2)
and $24 \fm 24 \pm 0.08$ (o3). We confirm the presence of an optical pulsar
wind nebula around PSR J0205+6449 and give an upper limit of $m_R \approx$ 24
for the optical magnitude of the pulsar. Furthermore we make the tentative
suggestion that our object o1, with an $m_R \approx$ 24.08 is the optical
counterpart. If confirmed the pulsar would have an $L_R/L_x\approx 0.004$ and
an optical efficiency of about 5% of the Crab pulsar. Such a low efficiency is
more consistent with the characteristic age of the pulsar rather than that of
SN 1181.


title:
Elastic properties of ternary arsenide SrFe2As2 and quaternary
  oxyarsenide LaOFeAs as basic phases for new 38-55K superconductors from first
  principles

abstract:
  Here we report the first-principle FLAPW-GGA calculations of the elastic
properties of two related phases, namely, the ternary arsenide SrFe2As2 and the
quaternary oxyarsenide LaOFeAs as the basic phases for the newly discovered
"1111" and "122" 38-52K superconductors. The independent elastic constants
(Cij), bulk moduli, compressibility, and shear moduli are evaluated and
discussed. Additionally, numerical estimates of the elastic parameters of the
polycrystalline LaOFeAs and SrFe2As2 ceramics are performed for the first time.


title:
Double Transverse-Spin Asymmetries for Drell-Yan Process in pp and
  p\bar{p} Collisions: Role of Nonleading QCD Corrections at Small Transverse
  Momentum

abstract:
  We discuss the double-spin asymmetries in transversely polarized Drell-Yan
process, calculating all-order gluon resummation corrections up to the
next-to-leading logarithmic accuracy. This resummation is relevant when the
transverse-momentum Q_T of the produced lepton pair is small, and reproduces
the (fixed-order) next-to-leading QCD corrections upon integrating over Q_T.
The resummation corrections behave differently between pp- and
p\bar{p}-collision cases and are small for the latter case at the kinematics in
the proposed GSI experiments. This fact allows us to predict large value of the
double-spin asymmetries at GSI, using the recent empirical information on the
transversity.


title: On the Oppenheim's "factorisatio numerorum" function

abstract:
  Let $f(n)$ denote the number of distinct unordered factorisations of the
natural number $n$ into factors larger than 1.In this paper, we address some
aspects of the function $f(n)$.


abstract:
  We calculate the Overhauser frequency shifts in semiconductor nanostructures
resulting from the hyperfine interaction between nonequilibrium electronic
spins and nuclear spins. The frequency shifts depend on the electronic local
density of states and spin polarization as well as the electronic and nuclear
spin relaxation mechanisms. Unlike previous calculations, our method accounts
for the electron confinement in low dimensional semiconductor nanostructures,
resulting in both nuclear spin polarizations and Overhauser shifts that are
strongly dependent on position. Our results explain previously puzzling
measurements of Overhauser shifts in an Al$_x$Ga$_{1-x}$As parabolic quantum
well by showing the connection between the electron spin lifetime and the
frequency shifts.


title: A Spanning Set for the space of Super Cusp forms

abstract:
  Aim of this article is the construction of a spanning set for the space of
super cusp forms on a complex bounded symmetric super domain B of rank 1 with
respect to a lattice. The main ingredients are a generalization of the Anosov
closing lemma for partially hyperbolic diffeomorphisms and an unbounded
realization of B, in particular Fourier decomposition at the cusps mapped to
infinity via a partial Cayley transformation. The elements of the spanning set
are in finite-to-one correspondence with closed geodesics, the number of
elements corresponding to a geodesic growing linearly with its length.


title:
solarFLAG hare and hounds: estimation of p-mode frequencies from
  Sun-as-star helioseismology data

abstract:
  We report on the results of the latest solarFLAG hare-and-hounds exercise,
which was concerned with testing methods for extraction of frequencies of
low-degree solar p modes from data collected by Sun-as-a-star observations. We
have used the new solarFLAG simulator, which includes the effects of correlated
mode excitation and correlations with background noise, to make artificial
timeseries data that mimic Doppler velocity observations of the Sun as a star.
The correlations give rise to asymmetry of mode peaks in the frequency power
spectrum. Ten members of the group (the hounds) applied their ``peak bagging''
codes to a 3456-day dataset, and the estimated mode frequencies were returned
to the hare (who was WJC) for comparison. Analysis of the results reveals a
systematic bias in the estimated frequencies of modes above approximately 1.8
mHz. The bias is negative, meaning the estimated frequencies systematically
underestimate the input frequencies.
  We identify two sources that are the dominant contributions to the frequency
bias. Both sources involve failure to model accurately subtle aspects of the
observed power spectral density in the part (window) of the frequency power
spectrum that is being fitted. One source of bias arises from a failure to
account for the power spectral density coming from all those modes whose
frequencies lie outside the fitting windows. The other source arises from a
failure to account for the power spectral density of the weak l=4 and 5 modes,
which are often ignored in Sun-as-a-star analysis. The Sun-as-a-star
peak-bagging codes need to allow for both sources, otherwise the frequencies
are likely to be biased.


title: Model human heart or brain signals

abstract:
  A new model is suggested and used to mimic various spatial or temporal
designs in biological or non biological formations where the focus is on the
normal or irregular electrical signals coming from human heart (ECG) or brain
(EEG). The electrical activities in several muscles (EMG) or neurons or other
organs of human or various animals, such as lobster pyloric neuron, guinea pig
inferior olivary neuron, sepia giant axon and mouse neocortical pyramidal
neuron and some spatial formations are also considered (in Appendix). In the
biological applications, several elements (cells or tissues) in an organ are
taken as various entries in a representative lattice (mesh) where the entries
are connected to each other in terms of some molecular diffusions or electrical
potential differences. The biological elements evolve in time (with the given
tissue or organ) in terms of the mentioned connections (interactions) besides
some individual feedings. The anatomical diversity of the species (or organs)
is handled in terms of various combinations of the assumptions and parameters
for the initial conditions, the connections and the feeding terms and so on. A
small number of (iterative) secular equations (coupled map) are solved for the
results with few parameters for each case. The same equations may be used for
simulation if random parameters are involved. The model, with simple
mathematics and easy software, may be followed besides or instead of the known
theoretical approaches. The basic aim of the present contribution is to mimic
various empirical data for some electrical activities of human heart or brain
(or various animals). The mentioned empirical data are available in various
experimental literatures (which are cited or the open access data are borrowed)
and the model results may be considered as in good agreement with them.


title:
Accuracy of minimal and optimal qubit tomography for finite-length
  experiments

abstract:
  Practical quantum state tomography is usually performed by carrying out
repeated measurements on many copies of a given state. The accuracy of the
reconstruction depends strongly on the dimensionality of the system and the
number of copies used for the measurements. We investigate the accuracy of an
experimental implementation of a minimal and optimal tomography scheme for one-
and two-qubit states encoded in the polarization of photons. A suitable
statistical model for the attainable accuracy is introduced.


title: Random XML sampling the Boltzmann way

abstract:
  In this article we present the prototype of a framework capable of producing,
with linear complexity, uniformly random XML documents with respect to a given
RELAX NG grammar. The generation relies on powerful combinatorial methods
together with numerical and symbolic resolution of polynomial systems.


title: WCET analysis of multi-level set-associative instruction caches

abstract:
  With the advent of increasingly complex hardware in real-time embedded
systems (processors with performance enhancing features such as pipelines,
cache hierarchy, multiple cores), many processors now have a set-associative L2
cache. Thus, there is a need for considering cache hierarchies when validating
the temporal behavior of real-time systems, in particular when estimating
tasks' worst-case execution times (WCETs). To the best of our knowledge, there
is only one approach for WCET estimation for systems with cache hierarchies
[Mueller, 1997], which turns out to be unsafe for set-associative caches. In
this paper, we highlight the conditions under which the approach described in
[Mueller, 1997] is unsafe. A safe static instruction cache analysis method is
then presented. Contrary to [Mueller, 1997] our method supports set-associative
and fully associative caches. The proposed method is experimented on
medium-size and large programs. We show that the method is most of the time
tight. We further show that in all cases WCET estimations are much tighter when
considering the cache hierarchy than when considering only the L1 cache. An
evaluation of the analysis time is conducted, demonstrating that analysing the
cache hierarchy has a reasonable computation time.


title:
Search for Top Squarks at Tevatron Inspired by Dark Matter and
  Electroweak Baryogenesis

abstract:
  The search for the top squark ($\widetilde{t}_{1}$) within the kinematic
reach of Tevatron Run II is of great contemporary interest. Such a
$\widetilde{t}_{1}$ can explain the baryon asymmetry of the universe provided
$120 ~GeV/c^{2} \leq m_{\widetilde{t}_{1}} \leq m_t$. Moreover if $\Delta m
\equiv m_{\widetilde{t}_{1}}$ - $m_{\widetilde\chi_1^0}$ is small, where
$\widetilde\chi_1^0$ is the LSP, the dark matter relic density as obtained from
the WMAP data may be explained via $\widetilde{t}_{1}$- LSP coannihilation. In
this scenario the decay $\widetilde{t}_{1} \to c \widetilde\chi_1^0$ is likely
to occur with 100 % branching ratio but for small $\Delta m$ the conventional
di-jet + $\not E_T$ signal becomes unobservable. We propose a new search
strategy based on the $2j + \not E_T$ signature accompanied by an isolated
cluster of energy which arises from a decaying heavy particle with
characteristic decay length. Our preliminary simulations with PYTHIA indicate
that for $100 ~GeV/c^{2} \le m_{\widetilde{t}_{1}} \le 130 ~GeV/c^{2}$ this
signal may be observable while somewhat lager $m_{\widetilde{t}_{1}}$ may still
provide hints of new physics.


title: Hopf decomposition and horospheric limit sets

abstract:
  By looking at the relationship between the recurrence properties of a
countable group action with a quasi-invariant measure and the structure of its
ergodic components we establish a simple general description of the Hopf
decomposition of the action into the conservative and the dissipative parts in
terms of the Radon--Nikodym derivatives of the action. As an application we
prove that the conservative part of the boundary action of a discrete group of
isometries of a Gromov hyperbolic space with respect to any invariant
quasi-conformal stream coincides (mod 0) with the big horospheric limit set of
the group.


title:
"Finite" Non-Gaussianities and Tensor-Scalar Ratio in Large Volume
  Swiss-Cheese Compactifications

abstract:
  Developing on the ideas of (section 4 of) [1] and [2] and using the
formalisms of [3] and [4], after inclusion of perturbative and non-perturbative
alpha' corrections to the Kaehler potential and (D1- and D3-) instanton
generated superpotential, we show the possibility of getting finite values for
the non-linear parameter f_{NL} while looking for non-Gaussianities in type IIB
compactifications on orientifolds of the Swiss Cheese Calabi-Yau
WCP^4[1,1,1,6,9] in the L(arge) V(olume) S(cenarios) limit. First we show that
in the context of multi-field slow-roll inflation, for the Calabi-Yau volume
V~10^5 and D3-instanton number n^s~10 along with N_e~18, one can realize
f_{NL}~0.03, and for Calabi-Yau volume V~10^6 with D3-instanton number n^s~10
resulting in number of e-foldings N_e~60, one can realize f_{NL}~0.01. Further
we show that with the slow-roll conditions violated and for the number of the
D3-instanton wrappings n^s ~O(1), one can realize f_{NL} ~O(1). Using general
considerations and some algebraic geometric assumptions, we show that with
requiring a "freezeout" of curvature perturbations at super horizon scales, it
is possible to get tensor-scalar ratio r ~O(10^{-3}) with the loss of scale
invariance |n_R-1|=0.01 and one can obtain f_{NL} ~O(10^{-2}) as well in the
context of slow-roll inflation scenarios in the same Swiss-Cheese setup. For
all our calculations the large values of the genus-zero Gopakumar-Vafa
invariants for compact projective varieties, play in important role. We also
make some observations pertaining to the possibility of the axionic inflaton
also being a cold dark matter candidate as well as a quintessence field used
for explaining dark energy.


title:
Minimal surfaces and harmonic diffeomorphisms from the complex plane
  onto a Hadamard surface

abstract:
  We construct harmonic diffeomorphisms from the complex plane $C$ onto any
Hadamard surface $M$ whose curvature is bounded above by a negative constant.
For that, we prove a Jenkins-Serrin type theorem for minimal graphs in $M\times
R$ over domains of $M$ bounded by ideal geodesic polygons and show the
existence of a sequence of minimal graphs over polygonal domains converging to
an entire minimal graph in $M\times R$ with the conformal structure of $C$.


title:
Hopping induced continuous diffusive dynamics below the non-ergodic
  transition

abstract:
  In low temperature supercooled liquid, below the ideal mode coupling theory
transition temperature, hopping and continuous diffusion are seen to coexist.
We present a theory which incorporates interaction between the two processes
and shows that hopping can induce continuous diffusion in the otherwise frozen
liquid. Several universal features arise from nonlinear interactions between
the continuous diffusive dynamics (described here by the mode coupling theory
(MCT)) and the activated hopping (described here by the random first order
transition theory). We apply the theory to real systems (Salol) to show that
the theory correctly predicts the temperature dependence of the non-exponential
stretching parameter, $\beta$, and the primary $\alpha$ relaxation timescale,
$\tau$. The study explains why, even below the ergodic to non-ergodic
transition, the dynamics is well described by MCT. The non-linear coupling
between the two dynamical processes modifies the relaxation behavior of the
structural relaxation from what would be predicted by a theory with a complete
static Gaussian barrier distribution in a manner that may be described as a
facilitation effect. Furthermore, the theory explains the observed variation of
the stretching exponent $\beta$ with the fragility parameter, $D$.


title:
The structure of renormalization Hopf algebras for gauge theories I:
  Representing Feynman graphs on BV-algebras

abstract:
  We study the structure of renormalization Hopf algebras of gauge theories. We
identify certain Hopf subalgebras in them, whose character groups are
semidirect products of invertible formal power series with formal
diffeomorphisms. This can be understood physically as wave function
renormalization and renormalization of the coupling constants, respectively.
After taking into account the Slavnov-Taylor identities for the couplings as
generators of a Hopf ideal, we find Hopf subalgebras in the corresponding
quotient as well.
  In the second part of the paper, we explain the origin of these Hopf ideals
by considering a coaction of the renormalization Hopf algebras on the
Batalin-Vilkovisky (BV) algebras generated by the fields and couplings
constants. The so-called classical master equation satisfied by the action in
the BV-algebra implies the existence of the above Hopf ideals in the
renormalization Hopf algebra. Finally, we exemplify our construction by
applying it to Yang-Mills gauge theory.


title: Searching for transit timing variations in transiting exoplanet systems

abstract:
  Searching for transit timing variations in the known transiting exoplanet
systems can reveal the presence of other bodies in the system. Here we report
such searches for two transiting exoplanet systems, TrES-1 and WASP-2. Their
new transits were observed with the 4.2m William Herschel Telescope located on
La Palma, Spain. In a continuing programme, three consecutive transits were
observed for TrES-1, and one for WASP-2 during September 2007. We used the
Markov Chain Monte Carlo simulations to derive transit times and their
uncertainties. The resulting transit times are consistent with the most recent
ephemerides and no conclusive proof of additional bodies in either system was
found.


title:
Bayesian Analysis of Marginal Log-Linear Graphical Models for Three Way
  Contingency Tables

abstract:
  This paper deals with the Bayesian analysis of graphical models of marginal
independence for three way contingency tables. We use a marginal log-linear
parametrization, under which the model is defined through suitable
zero-constraints on the interaction parameters calculated within marginal
distributions. We undertake a comprehensive Bayesian analysis of these models,
involving suitable choices of prior distributions, estimation, model
determination, as well as the allied computational issues. The methodology is
illustrated with reference to two real data sets.


title: Nonstandard model categories and homotopy theory

abstract:
  In order to apply nonstandard methods to questions of algebraic geometry we
continue our investigation from "Enlargements of categories" (Theory Appl.
Categ. 14 (2005), No. 16, 357--398) and show how important homotopical
constructions behave under enlargements.


title:
Non-Standard Neutrino Interactions with Matter from Physics Beyond the
  Standard Model

abstract:
  We investigate how non-standard neutrino interactions (NSIs) with matter can
be generated by new physics beyond the Standard Model (SM) and analyse the
constraints on the NSIs in these SM extensions. We focus on tree-level
realisations of lepton number conserving dimension 6 and 8 operators which do
not induce new interactions of four charged fermions (since these are already
quite constrained) and discard the possibility of cancellations between
diagrams with different messenger particles to circumvent experimental
constraints. The cases studied include classes of dimension 8 operators which
are often referred to as examples for ways to generate large NSIs with matter.
We find that, in the considered scenarios, the NSIs with matter are
considerably more constrained than often assumed in phenomenological studies,
at least ${\cal O}(10^{-2})$. The constraints on the flavour-conserving NSIs
turn out to be even stronger than the ones for operators which also produce
interactions of four charged fermions at the same level. Furthermore, we find
that in all studied cases the generation of NSIs with matter also gives rise to
NSIs at the source and/or detector of a possible future Neutrino Factory.


title:
Theory of the interaction forces and the heat transfer between moving
  bodies mediated by the fluctuating electromagnetic field

abstract:
  Within the framework of unified approach we study the Casimir-Lifshitz
interaction, the van der Waals friction force and the radiative heat transfer
at nonequilibrium conditions, when the interacting bodies are at different
temperatures, and they move relative to each other with the arbitrary velocity
$V$. The analysis is focused on the surface-surface and surface-particle
configuration. Our approach is based on the exact solution of electromagnetic
problem about the determination of the fluctuating electromagnetic field in the
vacuum gap between two flat parallel surfaces moving relative to each other
with the arbitrary velocity $V$. The velocity dependence of the considered
phenomena is determined by Doppler shift and can be strong for resonant photon
tunneling between surface modes.
  We show that relativistic effects give rise to a mixing of the contributions
from the electromagnetic waves with different polarization to the heat transfer
and the interaction forces. We find that these effects are of the order
$(V/c)^2$. The limiting case when one of the bodies is sufficiently rarefied
gives the heat transfer and the interaction forces between a moving small
particle and a surface.
  We also calculate the friction force acting on a particle moving with an
arbitrary velocity relative to the black body radiation.


title:
Catching Up Faster by Switching Sooner: A Prequential Solution to the
  AIC-BIC Dilemma

abstract:
  Bayesian model averaging, model selection and its approximations such as BIC
are generally statistically consistent, but sometimes achieve slower rates og
convergence than other methods such as AIC and leave-one-out cross-validation.
On the other hand, these other methods can br inconsistent. We identify the
"catch-up phenomenon" as a novel explanation for the slow convergence of
Bayesian methods. Based on this analysis we define the switch distribution, a
modification of the Bayesian marginal distribution. We show that, under broad
conditions,model selection and prediction based on the switch distribution is
both consistent and achieves optimal convergence rates, thereby resolving the
AIC-BIC dilemma. The method is practical; we give an efficient implementation.
The switch distribution has a data compression interpretation, and can thus be
viewed as a "prequential" or MDL method; yet it is different from the MDL
methods that are usually considered in the literature. We compare the switch
distribution to Bayes factor model selection and leave-one-out
cross-validation.

categories: math.ST cs.IT cs.LG math.IT stat.ME stat.ML stat.TH


title: Probing IGM large-scale flows: warps in galaxies at shells of voids

abstract:
  CONTEXT. Hydrodynamical cosmological simulations predict flows of the
intergalactic medium along the radial vector of the voids, approximately in the
direction of the infall of matter at the early stages of the galaxy formation.
  AIMS. These flows might be detected by analysing the dependence of the warp
amplitude on the inclination of the galaxies at the shells of the voids with
respect to the radial vector of the voids. This analysis will be the topic of
this paper.
  METHODS. We develop a statistical method of analysing the correlation of the
amplitude of the warp and the inclination of the galaxy at the void surface.
This is applied to a sample of 97 edge-on galaxies from the Sloan Digital Sky
Survey. Our results are compared with the theoretical expectations, which are
also derived in this paper.
  RESULTS. Our results allow us to reject the null hypothesis (i.e., the
non-correlation of the warp amplitude and the inclination of the galaxy with
respect to the void surface) at 94.4% C. L., which is not conclusive. The
absence of the radial flows cannot be excluded at present, although we can put
a constraint on the maximum average density of baryonic matter of the radial
flows of <rho_b> <~ 4 Omega_b rho_crit.