title: Implications of Leptonic Unitarity Violation at Neutrino Telescopes

abstract:
  A measurement of the ultrahigh-energy (UHE) cosmic neutrinos at a km^3-size
neutrino telescope will open a new window to constrain the 3 x 3 neutrino
mixing matrix V and probe possible new physics. We point out that it is in
principle possible to examine the non-unitarity of V, which is naturally
expected in a class of seesaw models with one or more TeV-scale Majorana
neutrinos, by using neutrino telescopes. Considering the UHE neutrinos produced
from the decays of charged pions arising from proton-proton and (or)
proton-gamma collisions at a distant astrophysical source, we show that their
flavor ratios at a terrestrial neutrino telescope may deviate from the
democratic flavor distribution \phi^T_e : \phi^T_\mu : \phi^T_\tau = 1 : 1 : 1
due to the seesaw-induced unitarity violation of V. Its effect can be as large
as several percent and can serve for an illustration of how sensitive a
neutrino telescope should be to this kind of new physics.


title:
Crystal structure and physical properties of half-doped manganite
  nanocrystals with size < 100nm

abstract:
  In this paper we report the structural and property (magnetic and electrical
transport) measurements of nanocrystals of half-doped
$\mathrm{La_{0.5}Ca_{0.5}MnO_3}$(LCMO) synthesized by chemical route, having
particle size down to an average diameter of 15nm. It was observed that the
size reduction leads to change in crystal structure and the room temperature
structure is arrested so that the structure does not evolve on cooling unlike
bulk samples. The structural change mainly affects the orthorhombic distortion
of the lattice. By making comparison with observed crystal structure data under
hydrostatic pressure it is suggested that the change in the crystal structure
of the nanocrystals occurs due to an effective hydrostatic pressure created by
the surface pressure on size reduction. This not only changes the structure but
also causes the room temperature structure to freeze-in. The size reduction
also does not allow the long supercell modulation needed for the Charge
Ordering, characteristic of this half-doped manganite, to set-in. The magnetic
and transport measurements also show that the Charge Ordering (CO) does not
occur when the size is reduced below a critical size. Instead, the nanocrystals
show ferromagnetic ordering down to the lowest temperatures along with metallic
type conductivity. Our investigation establishes a structural basis for the
destabilization of CO state observed in half-doped manganite nanocrystals.


title: Time reversal of Bose-Einstein condensates

abstract:
  Using Gross-Pitaevskii equation, we study the time reversibility of
Bose-Einstein condensates (BEC) in kicked optical lattices, showing that inside
the regime of quantum chaos the dynamics can be inverted from explosion to
collapse. The accuracy of time reversal decreases with the increase of atom
interactions inside BEC, until it is completely lost. Surprisingly, quantum
chaos helps to restore time reversibility. These predictions can be tested with
existing experimental setups.


title:
The Hard VHE Gamma-ray Emission in High-Redshift TeV Blazars:
  Comptonization of Cosmic Microwave Background Radiation in an Extended Jet?

abstract:
  Observations of very-high-energy (VHE, E > 250 GeV) gamma-ray emission from
several blazars at z > 0.1 have placed stringent constraints on the elusive
spectrum and intensity of the intergalactic infrared background radiation
(IIBR). Correcting their observed VHE spectrum for gamma-gamma absorption even
by the lowest plausible level of the IIBR provided evidence for a very hard
(photon spectral index Gamma_{ph} < 2) intrinsic source spectrum out to TeV
energies. Such a hard VHE gamma-ray spectrum poses a serious challenge to the
conventional synchrotron-self-Compton interpretation of the VHE emission of TeV
blazars and suggests the emergence of a separate emission component beyond a
few hundred GeV. Here we propose that such a very hard, slowly variable VHE
emission component in TeV blazars may be produced via Compton upscattering of
Cosmic Microwave Background (CMB) photons by shock-accelerated electrons in an
extended jet. For the case of 1ES 1101-232, this component could dominate the
bolometric luminosity of the extended jet if the magnetic fields are of the
order of typical intergalactic magnetic fields B ~ 10 micro-Gauss and electrons
are still being accelerated out to TeV energies gamma > 4 X 10^6) on kiloparsec
scales along the jet.


title:
Bosonic Quantum Gravity According to the Global One-Dimensionality
  Conjecture

abstract:
  In this paper, making use of the global one-dimensionality conjecture, we
discuss the reduction of the Wheeler-DeWitt quantum geometrodynamics to the
Klein-Gordon equation describing the scalar bosonic particle. The method of
second quantization in the appropriate Fock space is applied, and, employing
both the Bogoliubov transformation as well as Heisenberg equations of motion,
the quantum gravity is expressed as evolution of the creators and annihilators
related to the initial data. It is shown that this procedure leads to the
understanding of the boson mass, through the one-point two-boson quantum
correlations, as a scaled initial data mass.


title:
Critical dynamics of self-gravitating Langevin particles and bacterial
  populations

abstract:
  We study the critical dynamics of the generalized Smoluchowski-Poisson system
(for self-gravitating Langevin particles) or generalized Keller-Segel model
(for the chemotaxis of bacterial populations). These models [Chavanis & Sire,
PRE, 69, 016116 (2004)] are based on generalized stochastic processes leading
to the Tsallis statistics. The equilibrium states correspond to polytropic
configurations with index $n$ similar to polytropic stars in astrophysics. At
the critical index $n_{3}=d/(d-2)$ (where $d\ge 2$ is the dimension of space),
there exists a critical temperature $\Theta_{c}$ (for a given mass) or a
critical mass $M_{c}$ (for a given temperature). For $\Theta>\Theta_{c}$ or
$M<M_{c}$ the system tends to an incomplete polytrope confined by the box (in a
bounded domain) or evaporates (in an unbounded domain). For $\Theta<\Theta_{c}$
or $M>M_{c}$ the system collapses and forms, in a finite time, a Dirac peak
containing a finite fraction $M_c$ of the total mass surrounded by a halo. This
study extends the critical dynamics of the ordinary Smoluchowski-Poisson system
and Keller-Segel model in $d=2$ corresponding to isothermal configurations with
$n_{3}\to +\infty$. We also stress the analogy between the limiting mass of
white dwarf stars (Chandrasekhar's limit) and the critical mass of bacterial
populations in the generalized Keller-Segel model of chemotaxis.


title: Model of Dark Matter and Dark Energy Based on Gravitational Polarization

abstract:
  A model of dark matter and dark energy based on the concept of gravitational
polarization is investigated. We propose an action in standard general
relativity for describing, at some effective or phenomenological level, the
dynamics of a dipolar medium, i.e. one endowed with a dipole moment vector, and
polarizable in a gravitational field. Using first-order cosmological
perturbations, we show that the dipolar fluid is undistinguishable from
standard dark energy (a cosmological constant Lambda) plus standard dark matter
(a pressureless perfect fluid), and therefore benefits from the successes of
the Lambda-CDM (Lambda-cold dark matter) scenario at cosmological scales.
Invoking an argument of "weak clusterisation" of the mass distribution of
dipole moments, we find that the dipolar dark matter reproduces the
phenomenology of the modified Newtonian dynamics (MOND) at galactic scales. The
dipolar medium action naturally contains a cosmological constant, and we show
that if the model is to come from some fundamental underlying physics, the
cosmological constant Lambda should be of the order of a0^2/c^4, where a0
denotes the MOND constant acceleration scale, in good agreement with
observations.


title:
The future evolution and finite-time singularities in $F(R)$-gravity
  unifying the inflation and cosmic acceleration

abstract:
  We study the future evolution of quintessence/phantom dominated epoch in
modified $F(R)$-gravity which unifies the early-time inflation with late-time
acceleration and which is consistent with observational tests. Using the
reconstruction technique it is demonstrated that there are models where any
known (Big Rip, II, III or IV Type) singularity may classically occur. From
another side, in Einstein frame (scalar-tensor description) only IV Type
singularity occurs. Near the singularity the classical description breaks up,
it is demonstrated that quantum effects act against the singularity and may
prevent its appearance. The realistic $F(R)$-gravity which is future
singularity free is proposed. We point out that additional modification of any
$F(R)$-gravity by the terms relevant at the early universe is possible, in such
a way that future singularity does not occur even classically.


title: Kinetic description of particle emission from expanding source

abstract:
  The freeze out of the expanding systems, created in relativistic heavy ion
collisions, is discussed. We combine kinetic freeze out equations with Bjorken
type system expansion into a unified model. The important feature of the
proposed scenario is that physical freeze out is completely finished in a
finite time, which can be varied from 0 (freeze out hypersurface) to infinity.
The dependence of the post freeze out distribution function on the freeze out
time will be studied. As an example, model is completely solved and analyzed
for the gas of pions. We shall see that the basic freeze out features, pointed
out in the earlier works, are not smeared out by the expansion of the system.
The entropy evolution in such a scenario is also studied.


title: The HI content of the advanced merger NGC 4441

abstract:
  NGC 4441 is a candidate for a merger between a spiral and an elliptical
galaxy (S+E merger), because it shows typical tidal structures such as an
optical tail and two shells. With a far-infrared luminosity of $\sim 5\cdot
10^9 L_{\odot}$ this galaxy belongs to the class of moderate luminosity
mergers, in which the merging process induces (if at all) only a moderate
starburst. The study of the atomic gas content allows us to investigate the
merger history and the impact on the star formation. In particular, it is not
clear from simulations whether an S+E merger leads to a gas concentration in
the nucleus, resulting in a starburst, or whether the gas is spread out and
therefore too diffuse for new star forming regions. We used the Westerbork
Radio Synthesis Telescope to observe the properties of the HI. By using this
interferometer, we are able to study the large-scale HI distribution and
kinematics with high spatial and velocity resolution. We found two HI tails
extending out to more than 40 kpc. In a central disc, the gas shows a fairly
regular rotation pattern indicating that the gas started to settle after the
merger. The total HI mass adds up to $1.5 \cdot 10^9 M_{\odot}$. By comparing
the high resolution HI maps with deep optical images, differences between the
stellar and gaseous tidal features are apparent, which indicates an S+E merger
origin.


title: Statistical description of magnetic domains in the Ising model

abstract:
  We use the Mandelbrot-Zipfs power law for the description of the inhomogenity
of the spin system. We describe the statistical distributions of the domain's
masses in the Ising model near the phase transition induced by the temperature.
The statistical distribution near the critical point appears to be of the
Pareto type.


title:
Dynamics of saturated Bragg diffraction in a stored light grating in
  cold atoms

abstract:
  We report on a detailed investigation of the dynamics and the saturation of a
light grating stored in a sample of cold cesium atoms. We employ Bragg
diffraction to retrieve the stored optical information impressed into the
atomic coherence by the incident light fields. The diffracted efficiency is
studied as a function of the intensities of both writing and reading laser
beams. A theoretical model is developed to predict the temporal pulse shape of
the retrieved signal and compares reasonably well with the observed results.


title: Effects of current on nanoscale ring-shaped magnetic tunnel junctions

abstract:
  We report the observation and micromagnetic analysis of current-driven
magnetization switching in nanoscale ring-shaped magnetic tunnel junctions.
When the electric current density exceeds a critical value of the order of
$6\times 10^{6}$A/cm$^2$, the magnetization of the two magnetic rings can be
switched back and forth between parallel and antiparallel onion states.
Theoretical analysis and micromagnetic simulation show that the dominant
mechanism for the observed current-driven switching is the spin torque rather
than the current-induced circular Oersted field.


title:
One-rank interaction kernel of the two-nucleon system for medium and
  high energies

abstract:
  A new version of the separable kernel of the nucleon-nucleon interaction in
the Bethe-Salpeter approach is presented. The phase shifts are fitted to recent
experimental data for singlet and uncoupled triplet partial waves of the
neutron-proton scattering with total angular momenta J=0,1. The results are
compared with other model calculations.


title:
Towards planetesimals: dense chondrule clumps in the protoplanetary
  nebula

abstract:
  We outline a scenario which traces a direct path from freely-floating nebula
particles to the first 10-100km-sized bodies in the terrestrial planet region,
producing planetesimals which have properties matching those of primitive
meteorite parent bodies. We call this "primary accretion". The scenario draws
on elements of previous work, and introduces a new critical threshold for
planetesimal formation. We presume the nebula to be weakly turbulent, which
leads to dense concentrations of aerodynamically size-sorted particles having
properties like those observed in chondrites. The fractional volume of the
nebula occupied by these dense zones or clumps obeys a probability distribution
as a function of their density, and the densest concentrations have particle
mass density 100 times that of the gas. However, even these densest clumps are
prevented by gas pressure from undergoing gravitational instability in the
traditional sense (on a dynamical timescale). While in this state of arrested
development, they are susceptible to disruption by the ram pressure of the
differentially orbiting nebula gas. However, self-gravity can preserve
sufficiently large and dense clumps from ram pressure disruption, allowing
their entrained particles to sediment gently but inexorably towards their
centers, producing 10-100 km "sandpile" planetesimals. Localized radial
pressure fluctuations in the nebula, and interactions between differentially
moving dense clumps, will also play a role that must be allowed for in future
studies. The scenario is readily extended from meteorite parent bodies to
primary accretion throughout the solar system.


title: Evolving center-vortex loops

abstract:
  We consider coarse-graining applied to nonselfintersecting planar
center-vortex loops as they emerge in the confining phase of an SU(2)
Yang-Mills theory. Well-established properties of planar curve-shrinking
predict that a suitably defined, geometric effective action exhibits
(mean-field) critical behavior when the conformal limit of circular points is
reached. This suggests the existence of an asymptotic mass gap. We demonstrate
that the initially sharp mean center-of-mass position in a given ensemble of
curves develops a variance under the flow as is the case for a position
eigenstate in free-particle quantum mechanics under unitary time evolution. A
possible application of these concepts is an approach to high-$T_c$
superconductivity based (a) on the nonlocal nature of the electron (1-fold
selfintersecting center-vortex loop) and (b) on planar curve-shrinking flow
representing the decrease in thermal noise in a cooling cuprate.


title:
The Existence of Einstein Static Universes and their Stability in Fourth
  order Theories of Gravity

abstract:
  We investigate whether or not an Einstein Static universe is a solution to
the cosmological equations in $f(R)$ gravity. It is found that only one class
of $f(R)$ theories admits an Einstein Static model, and that this class is
neutrally stable with respect to vector and tensor perturbations for all
equations of state on all scales. Scalar perturbations are only stable on all
scales if the matter fluid equation of state satisfies
$c_s^2>\frac{\sqrt{5}-1}{6}\approx 0.21$. This result is remarkably similar to
the GR case, where it was found that the Einstein Static model is stable for
$c_s^2>{1/5}$.


title:
A consequence of the gravitational self-force for circular orbits of the
  Schwarzschild geometry

abstract:
  A small mass \mu in orbit about a much more massive black hole M moves along
a world line that deviates from a geodesic of the black hole geometry by
O(\mu/M). This deviation is said to be caused by the gravitational self-force
of the metric perturbation h_{ab} from \mu. For circular orbits about a
non-rotating black hole we numerically calculate the O(\mu/M) effects upon the
orbital frequency and upon the rate of passage of proper time on the worldline.
These two effects are independent of the choice of gauge for h_{ab} and are
observable in principle. For distant orbits, our numerical results agree with a
post-Newtonian analysis including terms of order (v/c)^6.


title: Khinchin theorem for integral points on quadratic varieties

abstract:
  We prove an analogue the Khinchin theorem for the Diophantine approximation
by integer vectors lying on a quadratic variety. The proof is based on the
study of a dynamical system on a homogeneous space of the orthogonal group. We
show that in this system, generic trajectories visit a family of shrinking
subsets infinitely often.


title: Practically secure quantum bit commitment based on quantum seals

abstract:
  The relationship between the quantum bit commitment (QBC) and quantum seal
(QS) is studied. It is elaborated that QBC and QS are not equivalent, but QS
protocols satisfying a stronger unconditional security requirement can lead to
an unconditionally secure QBC. In this sense, QS is strictly stronger than QBC
in security requirements. Based on an earlier proposal on sealing a single bit,
a feasible QBC protocol is also put forward, which is secure in practice even
if the cheater has a strong quantum computational power.


title: Force focusing in confined fibers and sheets

abstract:
  A thin fiber or sheet curled into a circular container has a detached region
whose shape and force ratios are independent of material properties and
container radius. We compute this shape and compare it with experiments. The
discrete forces acting at either end of the detached region have a ratio that
depends only on the length of the fiber or sheet relative to the circle radius.
We calculate this force ratio in three regimes of circle radius.


title:
Transmission-Line Analysis of Epsilon-Near-Zero (ENZ)-Filled Narrow
  Channels

abstract:
  Following our recent interest in metamaterial-based devices supporting
resonant tunneling, energy squeezing and supercoupling through narrow waveguide
channels and bends, here we analyze the fundamental physical mechanisms behind
this phenomenon using a transmission-line model. These theoretical findings
extend our theory, allowing us to take fully into account frequency dispersion
and losses and revealing the substantial differences between this unique
tunneling phenomenon and higher-frequency Fabry-Perot resonances. Moreover,
they represent the foundations for other possibilities to realize tunneling
through arbitrary waveguide bends, both in E and H planes of polarization,
waveguide connections and sharp abruptions and to obtain analogous effects with
geometries arguably simpler to realize.


title: No Higgs at the LHC

abstract:
  I discuss the question whether it is possible that the LHC will find no
signal for the Higgs particle. It is argued that in this case singlet scalars
should be present that could move in extra, even fractional, dimensions. A
critical view at the existing electroweak data shows that this possibility
might be favored over the simplest standard model. In this case one needs the
ILC in order to study the Higgs sector.


title: Aharonov-Bohm effect in superconducting LOFF state

abstract:
  We study AB oscillations of transition temperature, paraconductivity and
specific heat of thin ring in the regime of inhomogeneous Larkin - Ovchinnikov
- Fulde - Ferrell superconducting state. We found that in contrast to uniform
superconductivity magnetic flux might increase the critical temperature of LOFF
state. Degeneracy of the inhomogeneous superconducting state reveals in double
peak structure of AB oscillations.


title: Initial Conditions for Large Cosmological Simulations

abstract:
  This technical paper describes a software package that was designed to
produce initial conditions for large cosmological simulations in the context of
the Horizon collaboration. These tools generalize E. Bertschinger's Grafic1
software to distributed parallel architectures and offer a flexible alternative
to the Grafic2 software for ``zoom'' initial conditions, at the price of large
cumulated cpu and memory usage. The codes have been validated up to resolutions
of 4096^3 and were used to generate the initial conditions of large
hydrodynamical and dark matter simulations. They also provide means to generate
constrained realisations for the purpose of generating initial conditions
compatible with, e.g. the local group, or the SDSS catalog.


title:
Gauge invariance and the CPT and Lorentz violating induced
  Chern-Simons-like term in extended QED

abstract:
  The radiative induction of the CPT and Lorentz violating Chern-Simons (CS)
term is reassessed. The massless and massive models are studied. Special
attention is given to the preservation of gauge symmetry at higher orders in
the background vector $b_\mu$ when radiative corrections are considered. Both
the study of the odd and even parity sectors of the complete vacuum
polarization tensor at one-loop order and a non-perturbative analysis show that
this symmetry must be preserved by the quantum corrections. As a complement we
obtain that transversality of the polarization tensor does not fix the value of
the coefficient of the induced CS term.


title: Detecting transits from Earth-sized planets around Sun-like stars

abstract:
  Context. Detecting regular dips in the light curve of a star is an easy way
to detect the presence of an orbiting planet. COROT is a Franco-European
mission launched at the end of 2006, and one of its main objectives is to
detect planetary systems using the transit method. Aims. In this paper, we
present a new method for transit detection and determine the smallest detected
planetary radius, assuming a parent star like the Sun. Methods. We simulated
light curves with Poisson noise and stellar variability, for which data from
the VIRGO/PMO6 instrument on board SoHO were used. Transits were simulated
using the UTM software. Light curves were denoised by the mean of a low-pass
and a high-pass filter. The detection of periodic transits works on light
curves folded at several trial periods with the particularity that no rebinning
is performed after the folding. The best fit was obtain when all transits are
overlayed, i.e when the data are folded at the right period. Results. Assuming
a single data set lasting 150d, transits from a planet with a radius down to 2
Rearth can be detected. The efficiency depends neither on the transit duration
nor on the number of transits observed. Furthermore we simulated transits with
periods close to 150d in data sets containing three observations of 150d,
separated by regular gaps with the same length. Again, planets with a radius
down to 2 Rearth can be detected. Conclusions. Within the given range of
parameters, the detection efficiency depends slightly on the apparent magnitude
of the star but neither on the transit duration nor the number of transits.
Furthermore, multiple observations might represent a solution for the COROT
mission for detecting small planets when the orbital period is much longer than
the duration of a single observation.


title:
Positive and negative streamers in ambient air: modeling evolution and
  velocities

abstract:
  We simulate short positive and negative streamers in air at standard
temperature and pressure. They evolve in homogeneous electric fields or emerge
from needle electrodes with voltages of 10 to 20 kV. The streamer velocity at
given streamer length depends only weakly on the initial ionization seed,
except in the case of negative streamers in homogeneous fields. We characterize
the streamers by length, head radius, head charge and field enhancement. We
show that the velocity of positive streamers is mainly determined by their
radius and in quantitative agreement with recent experimental results both for
radius and velocity. The velocity of negative streamers is dominated by
electron drift in the enhanced field; in the low local fields of the present
simulations, it is little influenced by photo-ionization. Though negative
streamer fronts always move at least with the electron drift velocity in the
local field, this drift motion broadens the streamer head, decreases the field
enhancement and ultimately leads to slower propagation or even extinction of
the negative streamer.


title: Anisotropic spectra of acoustic type turbulence

abstract:
  We consider the problem of spectra for acoustic type of turbulence generated
by shocks being randomly distributed in space. We show that for turbulence with
a weak anisotropy such spectra have the same dependence in $k$-space as the
Kadomtsev-Petviashvili (KP) spectrum: $E(k)\sim k^{-2}$. However, the frequency
spectrum has always the falling $\sim \omega^{-2}$, independently on
anisotropy. In the strong anisotropic case the energy distribution relative to
wave vectors takes anisotropic dependence forming in the large $% k $ region
the spectra of the jet type.


title: A note on 2-subset-regular self-complementary 3-uniform hypergraphs

abstract:
  We show that a 2-subset-regular self-complementary 3-uniform hypergraph with
$n$ vertices exists if and only if $n\ge 6$ and $n$ is congruent to 2 modulo 4.


title: Experimental entanglement restoration on entanglement-breaking channels

abstract:
  Quantum entanglement, a fundamental property ensuring security of key
distribution and efficiency of quantum computing, is extremely sensitive to
decoherence. Different procedures have been developed in order to recover
entanglement after propagation over a noisy channel. However, besides a certain
amount of noise, entanglement is completely lost. In this case the channel is
called entanglement breaking and any multi-copy distillation methods cannot
help to restore even a bit of entanglement. We report the experimental
realization of a new method which restores entanglement from a single photon
entanglement breaking channel. The method based on measurement of environmental
light and quantum feed-forward correction can reveal entanglement even if this
one completely disappeared. This protocol provides new elements to overcome
decoherence effects.


title:
Feasibility Study for Measuring Geomagnetic Conversion of Solar Axions
  to X-rays in Low Earth Orbits

abstract:
  We present a detailed computation of the expected rate for Geomagnetic
Conversion of Solar Axions to X-rays (GECOSAX) along the orbit of an x-ray
satellite. We use realistic satellite orbits and propagation in time. A
realistic model for the Earth's magnetic field, which properly accounts for its
spatial non-uniformity, is used. We also account for the effect of the Earth's
atmosphere on the propagation of x-rays in our calculation of axion-photon
conversion probability. To estimate possible sensitivities to the axion-photon
coupling g_{a\gamma}, we use an actual measurement of the expected backgrounds
by the SUZAKU satellite. Assuming a detector area of 10^3 cm^2 and about 10^6 s
of data, we show that a 2 \sigma limit of g_{a\gamma} < (4.7-6.6) times
10^{-11} GeV^{-1} from GECOSAX is achievable, for axion masses m_a<10^{-4} eV.
This significantly exceeds current laboratory sensitivities to g_{a\gamma}.


title: Generating derivative structures: Algorithm and applications

abstract:
  We present an algorithm for generating all derivative superstructures--for
arbitrary parent structures and for any number of atom types. This algorithm
enumerates superlattices and atomic configurations in a geometry-independent
way. The key concept is to use the quotient group associated with each
superlattice to determine all unique atomic configurations. The run time of the
algorithm scales linearly with the number of unique structures found. We show
several applications demonstrating how the algorithm can be used in materials
design problems. We predict an altogether new crystal structure in Cd-Pt and
Pd-Pt, and several new ground states in Pd-rich and Pt-rich binary systems.


title: Deep Inelastic Processes and the Equations of Motion

abstract:
  We show that the Politzer theorem on the equations of motion implies
approximate constraints on the quark correlator, restricting considerably, for
sufficiently large Q^2, the number of independent distribution functions that
characterize the internal structure of the nucleon, and of independent
fragmentation functions. This result leads us to suggesting an alternative
method for determining transversity. Moreover our approach implies predictions
on the Q^2-dependence of some azimuthal asymmetries, like Sivers, Qiu-Sterman
and Collins asymmetry. Lastly, we discuss some implications on the
Burkhardt-Cottingham and Efremov-Leader-Teryaev sum rules.


title: Pressure-temperature phase diagram of ferromagnetic superconductors

abstract:
  The symmetry approach to the description of the (P,T) phase diagram of
ferromagnet superconductors with triplet pairing is developed. Taking into
account the recent experimental observations made on UCoGe it is considered the
case of a crystal with orthorhombic structure and strong spin-orbital coupling.
It is shown that formation of ferromagnet superconducting state from a
superconducting state is inevitably accompanied by the first order type
transition.


title: Path-integral molecular dynamics simulation of 3C-SiC

abstract:
  Molecular dynamics simulations of 3C-SiC have been performed as a function of
pressure and temperature. These simulations treat both electrons and atomic
nuclei by quantum mechanical methods. While the electronic structure of the
solid is described by an efficient tight-binding Hamiltonian, the nuclei
dynamics is treated by the path integral formulation of statistical mechanics.
To assess the relevance of nuclear quantum effects, the results of quantum
simulations are compared to others where either the Si nuclei, the C nuclei or
both atomic nuclei are treated as classical particles. We find that the
experimental thermal expansion of 3C-SiC is realistically reproduced by our
simulations. The calculated bulk modulus of 3C-SiC and its pressure derivative
at room temperature show also good agreement with the available experimental
data. The effect of the electron-phonon interaction on the direct electronic
gap of 3C-SiC has been calculated as a function of temperature and related to
results obtained for bulk diamond and Si. Comparison to available experimental
data shows satisfactory agreement, although we observe that the employed
tight-binding model tends to overestimate the magnitude of the electron-phonon
interaction. The effect of treating the atomic nuclei as classical particles on
the direct gap of 3C-SiC has been assessed. We find that non-linear quantum
effects related to the atomic masses are particularly relevant at temperatures
below 250 K.


title: On the classification of links up to finite type

abstract:
  We use an action, of 2l-component string links on l-component string links,
defined by the first author and Xiao-Song Lin, to lift the indeterminacy of
finite type link invariants. The set of links up to this new indeterminacy is
in bijection with the orbit space of the restriction of this action to the
stabilizer of the identity.
  Structure theorems for the sets of links up to C_n-equivalence and
Self-C_n-equivalence are also given.


title: Blow up and regularity for fractal Burgers equation

abstract:
  The paper is a comprehensive study of the existence, uniqueness, blow up and
regularity properties of solutions of the Burgers equation with fractional
dissipation. We prove existence of the finite time blow up for the power of
Laplacian $\alpha < 1/2,$ and global existence as well as analyticity of
solution for $\alpha \geq 1/2.$ We also prove the existence of solutions with
very rough initial data $u_0 \in L^p,$ $1 < p < \infty.$ Many of the results
can be extended to a more general class of equations, including the surface
quasi-geostrophic equation.


title: Some consequences of Schanuel's Conjecture

abstract:
  During the Arizona Winter School 2008 (held in Tucson, AZ) we worked on the
following problems:
  a) (Expanding a remark by S. Lang). Define $E_0 = \overline{\mathbb{Q}}$
Inductively, for $n \geq 1$, define $E_n$ as the algebraic closure of the field
generated over $E_{n-1}$ by the numbers $\exp(x)=e^x$, where $x$ ranges over
$E_{n-1}$. Let $E$ be the union of $E_n$, $n \geq 0$. Show that Schanuel's
Conjecture implies that the numbers $\pi, \log \pi, \log \log \pi, \log \log
\log \pi, \ldots $ are algebraically independent over $E$.
  b) Try to get a (conjectural) generalization involving the field $L$ defined
as follows. Define $L_0 = \overline{\mathbb{Q}}$. Inductively, for $n \geq 1$,
define $L_n$ as the algebraic closure of the field generated over $L_{n-1}$ by
the numbers $y$, where $y$ ranges over the set of complex numbers such that
$e^y\in L_{n-1}$. Let $L$ be the union of $L_n$, $n \geq 0$.
  We were able to prove that Schanuel's Conjecture implies $E$ and $L$ are
linearly disjoint over $\overline{\mathbb{Q}}$.


title: A noncommutative view on topology and order

abstract:
  In this paper we put forward the definition of particular subsets on a unital
C*-algebra, that we call isocones, and which reduce in the commutative case to
the set of continuous non-decreasing functions with real values for a partial
order relation defined on the spectrum of the algebra, which satisfies a
compatibility condition with the topology (complete separateness). We prove
that this space/algebra correspondence is a dual equivalence of categories,
which is in fact only a mild generalization of the Gelfand-Naimark duality.
Thus we can expect that general isocones could serve to define a notion of
noncommutative ordered spaces. We also explore some basic algebraic
constructions involving isocones, and classify those which are defined in
M_2(C).


title: Magnetic response enhancement via electrically induced magnetic moments

abstract:
  The realization of negative refraction in atomic gases requires a strong
magnetic response of the atoms. Current proposals for such systems achieve an
enhancement of the magnetic response by a suitable laser field configuration,
but still rely on high gas densities. Thus further progress is desirable, and
this requires an understanding of the precise mechanism for the enhancement.
Therefore, here we study the magnetic and electric response to a probe field
interacting with three-level atoms in ladder configuration. In our first model,
the three transitions are driven by a control field and the electric and
magnetic component of the probe field, giving rise to a closed interaction
loop. In a reference model, the coherent driving is replaced by an incoherent
pump field. A time-dependent analysis of the closed-loop system enables us to
identify the different contributions to the medium response. A comparison with
the reference system then allows one to identify the physical mechanism that
leads to the enhancement. It is found that the enhancement occurs at so-called
multiphoton resonance by a scattering of the coupling field and the electric
probe field mode into the magnetic probe field mode. Based on these results,
conditions for the enhancement are discussed.


title: Homological symbols and the Quillen conjecture

abstract:
  We formulate a "correct" version of the Quillen conjecture on linear group
homology for certain arithmetic rings and provide evidence for the new
conjecture. In this way we predict that the linear group homology has a direct
summand looking like an unstable form of Milnor K-theory and we call this new
theory "homological symbols algebra". As a byproduct we prove the Quillen
conjecture in homological degree two for the rank two and the prime 5.


title: Analysis of coupled heat and moisture transfer in masonry structures

abstract:
  Evaluation of effective or macroscopic coefficients of thermal conductivity
under coupled heat and moisture transfer is presented. The paper first gives a
detailed summary on the solution of a simple steady state heat conduction
problem with an emphasis on various types of boundary conditions applied to the
representative volume element -- a periodic unit cell. Since the results
essentially suggest no superiority of any type of boundary conditions, the
paper proceeds with the coupled nonlinear heat and moisture problem subjecting
the selected representative volume element to the prescribed macroscopically
uniform heat flux. This allows for a direct use of the academic or commercially
available codes. Here, the presented results are derived with the help of the
SIFEL (SIimple Finite Elements) system.


title: Transport in a Levy ratchet: Group velocity and distribution spread

abstract:
  We consider the motion of an overdamped particle in a periodic potential
lacking spatial symmetry under the influence of symmetric L\'evy noise, being a
minimal setup for a ``L\'evy ratchet.'' Due to the non-thermal character of the
L\'evy noise, the particle exhibits a motion with a preferred direction even in
the absence of whatever additional time-dependent forces. The examination of
the L\'evy ratchet has to be based on the characteristics of directionality
which are different from typically used measures like mean current and the
dispersion of particles' positions, since these get inappropriate when the
moments of the noise diverge. To overcome this problem, we discuss robust
measures of directionality of transport like the position of the median of the
particles displacements' distribution characterizing the group velocity, and
the interquantile distance giving the measure of the distributions' width.
Moreover, we analyze the behavior of splitting probabilities for leaving an
interval of a given length unveiling qualitative differences between the noises
with L\'evy indices below and above unity. Finally, we inspect the problem of
the first escape from an interval of given length revealing independence of
exit times on the structure of the potential.


title: Sur les quotients discrets de semi-groupes complexes

abstract:
  Let $X=G/K$ be an irreducible Hermitian symmetric space of the non-compact
type and let $S\in G^\mbb{C}$ be the associated compression semi-group. Let
$\Gamma$ be a discrete subgroup of $G$. We give a sufficient condition for
$\Gamma\backslash S$ to be a Stein manifold. Moreover, we show that in general
$\Gamma\backslash S$ is not Stein, which disproves a conjecture by Achab,
Betten and Kr\"otz.


title: Correlations among discontinuities in QCD phase diagram

abstract:
  We show, in general, that when a discontinuity of either zeroth-order or
first-order takes place in an order parameter such as the chiral condensate,
discontinuities of the same order emerge in other order parameters such as the
Polyakov loop. A condition for the coexistence theorem to be valid is
clarified. Consequently, only when the condition breaks down, zeroth-order and
first-order discontinuities can coexist on a phase boundary. We show with the
Polyakov-loop extended Nambu--Jona-Lasinio model that such a type of
coexistence is realized in the imaginary chemical potential region of the QCD
phase diagram. We also present examples of coexistence of the same-order
discontinuities in the real chemical potential region.


title:
Exponential Dichotomy and Trichotomy for Skew-Evolution Semiflows in
  Banach Spaces

abstract:
  The paper emphasizes the properties of exponential dichotomy and exponential
trichotomy for skew-evolution semiflows in Banach spaces, by means of evolution
semiflows and evolution cocycles. The approach is from uniform point of view.
Some characterizations which generalize classic results are also provided.


title:
Evolution of entanglement entropy following a quantum quench: Analytic
  results for the XY chain in a transverse magnetic field

abstract:
  The non-equilibrium evolution of the block entanglement entropy is
investigated in the XY chain in a transverse magnetic field after the
Hamiltonian parameters are suddenly changed from and to arbitrary values. Using
Toeplitz matrix representation and multidimensional phase methods, we provide
analytic results for large blocks and for all times, showing explicitly the
linear growth in time followed by saturation. The consequences of these
analytic results are discussed and the effects of a finite block length is
taken into account numerically.

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


title:
Right sneutrinos and the signals of a stable stop at the Large Hadron
  Collider

abstract:
  We investigate charged tracks signals of a supersymmetric scenario, where the
lighter stop is the next-to-lightest supersymmetric particle (NLSP). It is
found that such an NLSP is stable on the scale of the detector at the LHC if
one has a right-chiral sneutrino as the lightest supersymmetric particle (LSP).
After identifying some benchmark points in the parameter space of a
supergravity scenario with non-universal scalar masses, we study a few specific
classes of signals, namely, stop pair production and gluino pair production
followed by each decaying into a stop and a top. It is shown that proper
kinematic cuts remove the backgrounds in each case, and, while a few months'
worth of data is sufficient to have copious events in the first case, one may
require 300 $fb^{-1}$ for the other. One can also aspire to reconstruct the
gluino mass, using the `visible' stable NLSP tracks.


title:
Asymptotic expansion of the integrated density of states of a
  two-dimensional periodic Schrodinger operator

abstract:
  We prove the complete asymptotic expansion of the integrated density of
states of a two-dimensional Schrodinger operator with a smooth periodic
potential


title: Light-Front Holography and AdS/QCD Correspondence

abstract:
  Light-Front Holography is a remarkable consequence of the correspondence
between string theory in AdS space and conformal field theories in
physical-space time. It allows string modes $\Phi(z)$ in the AdS fifth
dimension to be precisely mapped to the light-front wavefunctions of hadrons in
terms of a specific light-front impact variable $\zeta$ which measures the
separation of the quark and gluonic constituents within the hadron. This
mapping was originally obtained by matching the exact expression for
electromagnetic current matrix elements in AdS space with the corresponding
exact expression for the current matrix element using light-front theory in
physical space-time. More recently we have shown that one obtains the identical
holographic mapping using matrix elements of the energy-momentum tensor, thus
providing an important consistency test and verification of holographic mapping
from AdS to physical observables defined on the light-front. The resulting
light-front Schrodinger equations predicted from AdS/QCD give a good
representation of the observed meson and baryon spectra and give excellent
phenomenological predictions for amplitudes such as electromagnetic form
factors and decay constants.


title: A note on Infraparticles and Unparticles

abstract:
  The observed astrophysical phenomenon of dark matter has generated new
interest in the problem of whether the principles underlying QFT are consistent
with invisibility/inertness of energy-momentum carrying "stuff" as e.g.
"unparticles". We show that the 2-dim. model which has been used to illustrate
the meaning of unparticles belongs to the class of former infraparticles models
and the latter are known to describe electrically charged particles in d=1+3
which despite their nonlocality are our best particle physics "candles". The
"invisibility" in this case refers to the infinite infrared photon cloud with
energies below the resolution and can be made arbitrarily small by increasing
the photon registering sensitivity. This is not quite the kind of invisibility
which the unparticle community attributes to their invisible "stuff" and which
would probably contradict the asymptotic completeness property. The main aim of
the present work is to show that knowledge about this part of QFT is still in
its infancy and express the hope that the work on unparticles may rekindle a
new interest in conceptually subtle old unsolved important problems.


title: Instantons and the 5D U(1) gauge theory with extra adjoint

abstract:
  In this paper we compute the partition function of 5D supersymmetric U(1)
gauge theory with extra adjoint matter in general $\Omega$-background. It is
well known that such partition functions encode very rich topological
information. We show in particular that unlike the case with no extra matter,
the partition function with extra adjoint at some special values of the
parameters directly reproduces the generating function for the Poincare
polynomial of the moduli space of instantons. Comparing our results with those
recently obtained by Iqbal et. al., who used the refined topological vertex
method, we present our comments on apparent discrepancies.


title:
Gauge Covariance of the Aharonov-Bohm Phase in Noncommutative Quantum
  Mechanics

abstract:
  The gauge covariance of the wave function phase factor in noncommutative
quantum mechanics (NCQM) is discussed. We show that the naive path integral
formulation and an approach where one shifts the coordinates of NCQM in the
presence of a background vector potential leads to the gauge non-covariance of
the phase factor. Due to this fact, the Aharonov-Bohm phase in NCQM which is
evaluated through the path-integral or by shifting the coordinates is neither
gauge invariant nor gauge covariant. We show that the gauge covariant
Aharonov-Bohm effect should be described by using the noncommutative Wilson
lines, what is consistent with the noncommutative Schr\"odinger equation. This
approach can ultimately be used for deriving an analogue of the Dirac
quantization condition for the magnetic monopole.


title:
Derivation of a Vacuum Refractive Index in a Stringy Space-Time Foam
  Model

abstract:
  It has been suggested that energetic photons propagating in vacuo should
experience a non-trivial refractive index due to the foamy structure of
space-time induced by quantum-gravitational fluctuations. The sensitivity of
recent astrophysical observations, particularly of AGN Mk501 by the MAGIC
Collaboration, approaches the Planck scale for a refractive index depending
linearly on the photon energy. We present here a new derivation of this
quantum-gravitational vacuum refraction index, based on a stringy analogue of
the interaction of a photon with internal degrees of freedom in a conventional
medium. We model the space-time foam as a gas of D-particles in the bulk
space-time of a higher-dimensional cosmology where the observable Universe is a
D3-brane. The interaction of an open string representing a photon with a
D-particle stretches and excites the string, which subsequently decays and
re-emits the photon with a time delay that increases linearly with the photon
energy and is related to stringy uncertainty principles. We relate this
derivation to other descriptions of the quantum-gravitational refractive index
in vacuo.


title: On the structure of k-Lie algebras

abstract:
  We show that the structure constants of $k$-Lie algebras, $k>3$, with a
positive definite metric are the sum of the volume forms of orthogonal
$k$-planes. This generalizes the result for $k=3$ in arXiv:0804.2662 and
arXiv:0804.3078, and confirms a conjecture in math/0211170.


title: A Monte Carlo Model for 'Jet Quenching'

abstract:
  We have developed the Monte Carlo simulation program JEWEL 1.0 (Jet Evolution
With Energy Loss), which interfaces a perturbative final state parton shower
with medium effects occurring in ultra-relativistic heavy ion collisions. This
is done by comparing for each jet fragment the probability of further
perturbative splitting with the density-dependent probability of scattering
with the medium. A simple hadronisation mechanism is included. In the absence
of medium effects, we validate JEWEL against a set of benchmark jet
measurements. For elastic interactions with the medium, we characterise not
only the medium-induced modification of the jet, but also the jet-induced
modification of the medium. Our main physics result is the observation that
collisional and radiative medium modifications lead to characteristic
differences in the jet fragmentation pattern, which persist above a soft
background cut. We argue that this should allow to disentangle collisional and
radiative parton energy loss mechanisms by measuring the n-jet fraction or a
class of jet shape observables.


title:
Crystallographic Phase Transition and High-Tc Superconductivity in
  LaFeAsO:F

abstract:
  Undoped LaFeAsO, parent compound of the newly found high-Tc superconductor,
exhibits a sharp decrease in the temperature-dependent resistivity at ~160 K.
The anomaly can be suppressed by F doping and the superconductivity appears
correspondingly, suggesting a close associate of the anomaly with the
superconductivity. We examined the crystal structures, magnetic properties and
superconductivity of undoped (normal conductor) and 14 at.% F-doped LaFeAsO (Tc
= 20 K) by synchrotron X-ray diffraction, DC magnetic measurements, and ab
initio calculations to demonstrate that the anomaly is associated with a phase
transition from tetragonal (P4/nmm) to orthorhombic (Cmma) phases at ~160 K as
well as an antiferromagnetic transition at ~140 K. These transitions can be
explained by spin configuration-dependent potential energy surfaces derived
from the ab initio calculations. The suppression of the transitions is ascribed
to interrelated effects of geometric and electronic structural changes due to
doping by F- ions.


title: Cosmological Signature of Tachyon Condensation

abstract:
  We consider the dynamics of the open string tachyon condensation in a
framework of the cubic fermionic String Field Theory including a non-minimal
coupling with closed string massless modes, the graviton and the dilaton.
Coupling of the open string tachyon and the dilaton is motivated by the open
String Field Theory in a linear dilaton background and the flat space-time. We
note that the dilaton gravity provides several restrictions on the tachyon
condensation and show explicitly that the influence of the dilaton on the
tachyon condensation is essential and provides a significant effect:
oscillations of the Hubble parameter and the state parameter become of a
cosmological scale. We give an estimation for the period of these oscillations
(0.1-1) Gyr and note a good agreement of this period with the observed
oscillations with a period (0.15-0.65) Gyr in a distribution of quasar spectra.


title: Effect of radiation on transport in graphene

abstract:
  We study transport properties of graphene-based p-n junctions irradiated by
an electromagnetic field (EF). The resonant interaction of propagating
quasiparticles with an external monochromatic radiation opens dynamical gaps in
their spectrum, resulting in a strong modification of current-voltage
characteristics of the junctions. The values of the gaps are proportional to
the amplitude of EF. We find that the transmission of the quasiparticles in the
junctions is determined by the tunneling through the gaps, and can be fully
suppressed when applying a sufficiently large radiation power. However, EF can
not only suppress the current but also generate it. We demonstrate that if the
height of the potential barrier exceeds a half of the photon energy, the
directed current (photocurrent) flows through the junction without any dc bias
voltage applied. Such a photocurrent arises as a result of inelastic
quasiparticle tunneling assisted by one- or two-photon absorption. We calculate
current-voltage characteristics of diverse graphene based junctions and
estimate their parameters necessary for the experimental observation of the
photocurrent and transmission suppression.


title:
Matrix biorthogonal polynomials on the unit circle and non-Abelian
  Ablowitz-Ladik hierarchy

abstract:
  Adler and van Moerbeke \cite{AVM} described a reduction of 2D-Toda hierarchy
called Toeplitz lattice. This hierarchy turns out to be equivalent to the one
originally described by Ablowitz and Ladik \cite{AL} using semidiscrete
zero-curvature equations. In this paper we obtain the original semidiscrete
zero-curvature equations starting directly from the Toeplitz lattice and we
generalize these computations to the matrix case. This generalization lead us
to the semidiscrete zero-curvature equations for the non-abelian (or
multicomponent) version of Ablowitz-Ladik equations \cite{GI}. In this way we
extend the link between biorthogonal polynomials on the unit circle and
Ablowitz-Ladik hierarchy to the matrix case.


title:
The environmental dependence of neutral hydrogen content in spiral
  galaxies

abstract:
  We present a study of the relationship between the deficiency of neutral
hydrogen and the local three-dimensional number density of spiral galaxies in
the Arecibo catalog of global HI measurements (Springob et al. 2005). We find
that the dependence on density of the HI content is weak at low densities, but
increases sharply at high densities where interactions between galaxies and the
intra-cluster medium become important. This behavior is reminiscent of the
morphology-density relation (Dressler 1980) in that the effect manifests itself
only at cluster-type densities, and indeed when we plot both the HI
deficiency-density and morphology-density relations, we see that the densities
at which they "turn up" are similar. This suggests that the physical mechanisms
responsible for the increase in early types in clusters are also responsible
for the decrease in HI content.


title: A puzzling millisecond pulsar companion in NGC 6266

abstract:
  We report on the optical identification of the companion to the eclipsing
millisecond pulsar PSR J1701$-$3006B in the globular cluster NGC 6266. A
relatively bright star with an anomalous red colour and an optical variability
($\sim$ 0.2 mag) that nicely correlates with the orbital period of the pulsar
($\sim$ 0.144 days) has been found nearly coincident with the pulsar nominal
position. This star is also found to lie within the error box position of an
X-ray source detected by Chandra observations, thus supporting the hypothesis
that some interaction is occurring between the pulsar wind and the gas
streaming off the companion. Although the shape of the optical light curve is
suggestive of a tidally deformed star which has nearly completely filled its
Roche lobe, the luminosity ($\sim 1.9 L_\odot$) and the surface temperature
($\sim 6000$ K) of the star, deduced from the observed magnitude and colours,
would imply a stellar radius significantly larger than the Roche lobe radius.
Possible explanations for this apparent inconsistency are discussed.


title: Isotropic PCA and Affine-Invariant Clustering

abstract:
  We present a new algorithm for clustering points in R^n. The key property of
the algorithm is that it is affine-invariant, i.e., it produces the same
partition for any affine transformation of the input. It has strong guarantees
when the input is drawn from a mixture model. For a mixture of two arbitrary
Gaussians, the algorithm correctly classifies the sample assuming only that the
two components are separable by a hyperplane, i.e., there exists a halfspace
that contains most of one Gaussian and almost none of the other in probability
mass. This is nearly the best possible, improving known results substantially.
For k > 2 components, the algorithm requires only that there be some
(k-1)-dimensional subspace in which the emoverlap in every direction is small.
Here we define overlap to be the ratio of the following two quantities: 1) the
average squared distance between a point and the mean of its component, and 2)
the average squared distance between a point and the mean of the mixture. The
main result may also be stated in the language of linear discriminant analysis:
if the standard Fisher discriminant is small enough, labels are not needed to
estimate the optimal subspace for projection. Our main tools are isotropic
transformation, spectral projection and a simple reweighting technique. We call
this combination isotropic PCA.


title:
Geometry of the energy landscape and folding transition in a simple
  model of a protein

abstract:
  A geometric analysis of the global properties of the energy landscape of a
minimalistic model of a polypeptide is presented, which is based on the
relation between dynamical trajectories and geodesics of a suitable manifold,
whose metric is completely determined by the potential energy. We consider
different sequences, some with a definite protein-like behavior, a unique
native state and a folding transition, and the others undergoing a hydrophobic
collapse with no tendency to a unique native state. The global geometry of the
energy landscape appears to contain relevant information on the behavior of the
various sequences: in particular, the fluctuations of the curvature of the
energy landscape, measured by means of numerical simulations, clearly mark the
folding transition and allow to distinguish the protein-like sequences from the
others.


title: Log minimal models according to Shokurov

abstract:
  Following Shokurov's ideas, we give a short proof of the following klt
version of his result: termination of terminal log flips in dimension d implies
that any klt pair of dimension d has a log minimal model or a Mori fibre space.
Thus, in particular, any klt pair of dimension 4 has a log minimal model or a
Mori fibre space.


title: Behavior of magnetic fields around the cosmic recombination

abstract:
  Several mechanisms have been proposed to generate primordial magnetic fields
and it is often assumed that magnetic fields are not affected by a sharp drop
in ionization rate due to the cosmic recombination. We investigate the validity
of the assumption by studying the behavior of magnetic fields and fluid motion
around recombination. Fluid equations including the effect of recombination are
considered for protons, electrons and neutral hydrogens separately, combining
Maxwell equations. We find that the residual ionization rate required for the
conservation of magnetic field at cosmological scales is about $10^{-10}$,
which is much smaller than the standard value $\sim 10^{-4}$. Further we will
show the acceleration of protons and electrons in the process of recombination
which conpensates the decrease in the carrier of electric current in order to
preserve electric current and then magnetic fields.


title:
Order-reducing Form Symmetries and Semiconjugate Factorizations of
  Difference Equations

abstract:
  The scalar difference equation $x_{n+1}=f_{n}(x_{n},x_{n-1},...,x_{n-k})$ may
exhibit symmetries in its form that allow for reduction of order through
substitution or a change of variables. Such form symmetries can be defined
generally using the semiconjugate relation on a group which yields a reduction
of order through the semiconjugate factorization of the difference equation of
order $k+1$ into equations of lesser orders. Different classes of equations are
considered including separable equations and homogeneous equations of degree 1.
Applications include giving a complete factorization of the linear
non-homogeneous difference equation of order $k+1$ into a system of $k+1$ first
order linear non-homogeneous equations in which the coefficients are the
eigenvalues of the higher order equation. Form symmetries are also used to
explain the complicated multistable behavior of a separable, second order
exponential equation.


title:
Recent Progress and New Challenges in Isospin Physics with Heavy-Ion
  Reactions

abstract:
  The ultimate goal of studying isospin physics via heavy-ion reactions with
neutron-rich, stable and/or radioactive nuclei is to explore the isospin
dependence of in-medium nuclear effective interactions and the equation of
state of neutron-rich nuclear matter, particularly the isospin-dependent term
in the equation of state, i.e., the density dependence of the symmetry energy.
Because of its great importance for understanding many phenomena in both
nuclear physics and astrophysics, the study of the density dependence of the
nuclear symmetry energy has been the main focus of the intermediate-energy
heavy-ion physics community during the last decade, and significant progress
has been achieved both experimentally and theoretically. In particular, a
number of phenomena or observables have been identified as sensitive probes to
the density dependence of the nuclear symmetry energy. Experimental studies
have confirmed some of these interesting isospin-dependent effects and allowed
us to constrain relatively stringently the symmetry energy at sub-saturation
densities. The impacts of this constrained density dependence of the symmetry
energy on the properties of neutron stars have also been studied, and they were
found to be very useful for the astrophysical community. With new opportunities
provided by the various radioactive beam facilities being constructed around
the world, the study of isospin physics is expected to remain one of the
forefront research areas in nuclear physics. In this report, we review the
major progress achieved during the last decade in isospin physics with heavy
ion reactions and discuss future challenges to the most important issues in
this field.


title: A colimit of classifying spaces

abstract:
  We recall a group-theoretic description of the first non-vanishing homotopy
group of a certain (n+1)-ad of spaces and show how it yields several formulae
for homotopy and homology groups of specific spaces. In particular we obtain an
alternative proof of J. Wu's group-theoretic description of the homotopy groups
of a 2-sphere.


title: Measure conjugacy invariants for actions of countable sofic groups

abstract:
  Sofic groups were defined implicitly by Gromov in [Gr99] and explicitly by
Weiss in [We00]. All residually finite groups (and hence every linear group) is
sofic. The purpose of this paper is to introduce, for every countable sofic
group $G$, a family of measure-conjugacy invariants for measure-preserving
$G$-actions on probability spaces. These invariants generalize Kolmogorov-Sinai
entropy for actions of amenable groups. They are computed exactly for Bernoulli
shifts over $G$, leading to a complete classification of Bernoulli systems up
to measure-conjugacy for many groups including all countable linear groups.
Recent rigidity results of Y. Kida and S. Popa are utilized to classify
Bernoulli shifts over mapping class groups and property T groups up to orbit
equivalence and von Neumann equivalence respectively.


title: Matching Interdiction

abstract:
  In the matching interdiction problem, we are given an undirected graph with
weights and interdiction costs on the edges and seek to remove a subset of the
edges constrained to some budget, such that the weight of a maximum weight
matching in the remaining graph is minimized. In this work we introduce the
matching interdiction problem and show that it is strongly NP-complete even
when the input is restricted to simple, bipartite graphs with unit edge weights
and unit interdiction costs. Furthermore, we present a pseudo-polynomial
algorithm for solving the matching interdiction problem on graphs with bounded
treewidth. The proposed algorithm extends the approach that is typically used
for the creation of efficient algorithms on graphs with bounded treewidth to
interdiction problems.


title:
Dynamics of viscous dissipative gravitational collapse: A full causal
  approach

abstract:
  The Misner and Sharp approach to the study of gravitational collapse is
extended to the viscous dissipative case in, both, the streaming out and the
diffusion approximations. The dynamical equation is then coupled to causal
transport equations for the heat flux, the shear and the bulk viscosity, in the
context of Israel--Stewart theory, without excluding the thermodynamics
viscous/heat coupling coefficients. The result is compared with previous works
where these later coefficients were neglected and viscosity variables were not
assumed to satisfy causal transport equations. Prospective applications of this
result to some astrophysical scenarios are discussed.


title: Spin noise at an arbitrary spin temperature

abstract:
  An ensemble of spins oriented along the $z$ direction exhibits nonzero
fluctuation in the transverse ($x$- and $y$-) components of the spin angular
momentum in accordance with the uncertainty principle. When the spins obey a
spin temperature distribution, the mean square fluctuation in $S_{x}$ can be
calculated by ensemble average of the expectation value of $S_{x}^{2}$ with
respect to an equilibrium density matrix $\rho =e^{\beta S_{z}}/Z$. The
fluctuation can also be calculated from the fluctuation-dissipation theorem as
has been done in literature in the context of NMR spin noise. For spin 1/2
particles in the high temperature limit, appropriate for many NMR experiments,
the two methods are known to produce the same, temperature-independent spin
noise. We show that inclusion of the zero-point fluctuation term in the
original Nyquist relation extends this correspondence to an arbitrary spin
temperature for any spin $S$. This indicates that the uncertainty
principle-limited spin projection noise can be viewed as a result of the
zero-point fluctuation in the thermal bath coupled to the spins.


title:
Rigidity of measures invariant under the action of a multiplicative
  semigroup of polynomial growth on $\T$

abstract:
  We prove that if a Borel probability measure (\mu) on (\T) is invariant under
the action of a "large" multiplicative semigroup (lower logarithmic density is
positive) and the action of the whole semigroup is ergodic then (\mu) is either
Lebesgue or has finite support.


title: Tensor categories: A selective guided tour

abstract:
  These are the lecture notes for a short course on tensor categories. The
coverage in these notes is relatively non-technical, focussing on the essential
ideas. They are meant to be accessible for beginners, but it is hoped that also
some of the experts will find something interesting in them.
  Once the basic definitions are given, the focus is mainly on k-linear
categories with finite dimensional hom-spaces. Connections with quantum groups
and low dimensional topology are pointed out, but these notes have no
pretension to cover the latter subjects at any depth. Essentially, these notes
should be considered as annotations to the extensive bibliography.


title:
Twisted Poincare Invariance, Noncommutative Gauge Theories and UV-IR
  Mixing

abstract:
  In the absence of gauge fields, quantum field theories on the
Groenewold-Moyal (GM) plane are invariant under a twisted action of the
Poincare group if they are formulated following [1, 2, 3, 4, 5, 6]. In that
formulation, such theories also have no UV-IR mixing [7]. Here we investigate
UV-IR mixing in gauge theories with matter following the approach of [3, 4]. We
prove that there is UV-IR mixing in the one-loop diagram of the S-matrix
involving a coupling between gauge and matter fields on the GM plane, the gauge
field being nonabelian. There is no UV-IR mixing if it is abelian.


title: Confirmation of a Kinematic Diagnostic for Face-On B/P Bulges

abstract:
  We present the results of high resolution absorption-line spectroscopy of 3
face-on galaxies, NGC 98, NGC 600, and NGC 1703 with the aim of searching for
box/peanut (B/P)-shaped bulges. These observations test and confirm, for the
first, time the prediction that face-on B/P-shaped bulges can be recognized by
two minima in the profile along the bar's major axis of the fourth
Gauss-Hermite moment h_4 of the line-of-sight velocity distribution (LOSVD). In
NGC 98, a clear double minimum in h_4 is present along the major axis of the
bar and before the end of the bar, as predicted. In contrast, in NGC 600, which
is also a barred galaxy but lacks a substantial bulge, we do not find any
significant kinematic signature for a B/P-shaped bulge. In NGC 1703, which is
an unbarred control galaxy, we found no evidence of a B/P bulge. We also show
directly that the LOSVD is broader at the location of the h_4 minimum in NGC 98
than elsewhere. This more direct method avoids possible artifacts associated
with the degeneracy between the measurement of line-of-sight velocity
dispersion and h_4.


title:
Metallicity and Alpha-Element Abundance Measurement in Red Giant Stars
  from Medium Resolution Spectra

abstract:
  We present a technique that applies spectral synthesis to medium resolution
spectroscopy (MRS, R ~ 6000) in the red (6300 A < lambda < 9100 A) to measure
[Fe/H] and [alpha/Fe] of individual red giant stars over a wide metallicity
range. We apply our technique to 264 red giant stars in seven Galactic globular
clusters and demonstrate that it reproduces the metallicities and alpha
enhancements derived from high resolution spectroscopy (HRS). The MRS technique
excludes the three Ca II triplet lines and instead relies on a plethora of
weaker lines. Unlike empirical metallicity estimators, such as the equivalent
width of the Ca II triplet, the synthetic method presented here is applicable
over an arbitrarily wide metallicity range and is independent of assumptions
about the alpha enhancement. Estimates of cluster mean [Fe/H] from different
HRS studies show typical scatter of ~0.1 dex but can be larger than 0.2 dex for
metal-rich clusters. The scatter in HRS abundance estimates among individual
stars in a given cluster is also comparable to 0.1 dex. By comparison, the
scatter among MRS [Fe/H] estimates of individual stars in a given cluster is
~0.1 dex for most clusters but 0.17 dex for the most metal-rich cluster, M71
(<[Fe/H]> = -0.8). A star-by-star comparison of HRS vs. MRS [alpha/Fe]
estimates indicates that the precision in [alpha/Fe]_MRS is 0.05 dex. The
errors in [Fe/H]_MRS and [alpha/Fe]_MRS increase beyond 0.25 dex only below
signal-to-noise ratios of 20 A^(-1), which is typical for existing MRS of the
red giant stars in Leo I, one of the most distant Milky Way satellites (250
kpc).


title: Topological order in a 3D toric code at finite temperature

abstract:
  We study topological order in a toric code in three spatial dimensions, or a
3+1D Z_2 gauge theory, at finite temperature. We compute exactly the
topological entropy of the system, and show that it drops, for any
infinitesimal temperature, to half its value at zero temperature. The remaining
half of the entropy stays constant up to a critical temperature Tc, dropping to
zero above Tc. These results show that topologically ordered phases exist at
finite temperatures, and we give a simple interpretation of the order in terms
of fluctuating strings and membranes, and how thermally induced point defects
affect these extended structures. Finally, we discuss the nature of the
topological order at finite temperature, and its quantum and classical aspects.


title: Typicality Derived

abstract:
  Hartle and Srednicki have suggested that standard quantum theory does not
favor our typicality. Here an alternative version is proposed in which
typicality is likely, Eventual Quantum Mechanics. This version allows one to
calculate normalized probabilities for alternatives obeying what I call the
Principle of Observational Discrimination, that each possible complete
observation or data set should uniquely distinguish one element from the set of
alternatives.


title:
Polaris the Cepheid returns: 4.5 years of monitoring from ground and
  space

abstract:
  We present the analysis of 4.5 years of nearly continuous observations of the
classical Cepheid Polaris, which comprise the most precise data available for
this star. We have made spectroscopic measurements from ground and photometric
measurements from the WIRE star tracker and the SMEI instrument on the Coriolis
satellite. Measurements of the amplitude of the dominant oscillation (P = 4
days), that go back more than a century, show a decrease from 120 mmag to 30
mmag (V magnitude) around the turn of the millennium. It has been speculated
that the reason for the decrease in amplitude is the evolution of Polaris
towards the edge of the instability strip. However, our new data reveal an
increase in the amplitude by about 30% from 2003-2006. It now appears that the
amplitude change is cyclic rather than monotonic, and most likely the result of
a pulsation phenomenon. In addition, previous radial velocity campaigns have
claimed the detection of long-period variation in Polaris (P > 40 days). Our
radial velocity data are more precise than previous datasets, and we find no
evidence for additional variation for periods in the range 3-50 days with an
upper limit of 100 m/s. However, in the WIRE data we find evidence of variation
on time-scales of 2-6 days, which we interpret as being due to granulation.


title:
Pseudo-magnetic catalysis of the time-reversal symmetry breaking in
  graphene

abstract:
  Finite flux of the (time-reversal-symmetric) pseudo-magnetic field, which
represents the effect of wrinkling of the graphene sheet for example, is shown
to be a catalyst for spontaneous breaking of the time-reversal symmetry of
Dirac fermions in two dimensions. Possible experimental consequences of this
effect for graphene are discussed.


title: Time Dilation in Type Ia Supernova Spectra at High Redshift

abstract:
  We present multiepoch spectra of 13 high-redshift Type Ia supernovae (SNe Ia)
drawn from the literature, the ESSENCE and SNLS projects, and our own separate
dedicated program on the ESO Very Large Telescope. We use the Supernova
Identification (SNID) code of Blondin & Tonry to determine the spectral ages in
the supernova rest frame. Comparison with the observed elapsed time yields an
apparent aging rate consistent with the 1/(1+z) factor (where z is the
redshift) expected in a homogeneous, isotropic, expanding universe. These
measurements thus confirm the expansion hypothesis, while unambiguously
excluding models that predict no time dilation, such as Zwicky's "tired light"
hypothesis. We also test for power-law dependencies of the aging rate on
redshift. The best-fit exponent for these models is consistent with the
expected 1/(1+z) factor.


title:
Stellar dynamical evidence against a cold disc origin for stars in the
  Galactic Centre

abstract:
  Observations of massive stars within the central parsec of the Galaxy show
that, while most stars orbit within a well-defined disc, a significant fraction
have large eccentricities and / or inclinations with respect to the disc plane.
Here, we investigate whether this dynamically hot component could have arisen
via scattering from an initially cold disc -- the expected initial condition if
the stars formed from the fragmentation of an accretion disc. Using N-body
methods, we evolve a variety of flat, cold, stellar systems, and study the
effects of initial disc eccentricity, primordial binaries, very massive stars
and intermediate mass black holes. We find, consistent with previous results,
that a circular disc does not become eccentric enough unless there is a
significant population of undetected 100--1000 Msun objects. However, since
fragmentation of an eccentric disc can readily yield eccentric stellar orbits,
the strongest constraints come from inclinations. We show that_none_ of our
initial conditions yield the observed large inclinations, regardless of the
initial disc eccentricity or the presence of massive objects. These results
imply that the orbits of the young massive stars in the Galactic Centre are
largely primordial, and that the stars are unlikely to have formed as a
dynamically cold disc.


title: Supernova 1996cr: SN 1987A's Wild Cousin?

abstract:
  We report on new VLT optical spectroscopic and multi-wavelength archival
observations of SN1996cr, a previously identified ULX known as Circinus Galaxy
X-2. Our optical spectrum confirms SN1996cr as a bona fide type IIn SN, while
archival imaging isolates its explosion date to between 1995-02-28 and
1996-03-16. SN1996cr is one of the closest SNe (~3.8 Mpc) in the last several
decades and in terms of flux ranks among the brightest radio and X-ray SNe ever
detected. The wealth of optical, X-ray, and radio observations that exist for
this source provide relatively detailed constraints on its post-explosion
expansion and progenitor history, including an preliminary angular size
constaint from VLBI. The archival X-ray and radio data imply that the
progenitor of SN1996cr evacuated a large cavity just prior to exploding: the
blast wave likely expanded for ~1-2 yrs before eventually striking the dense
circumstellar material which surrounds SN1996cr. The X-ray and radio emission,
which trace the progenitor mass-loss rate, have respectively risen by a factor
of ~2 and remained roughly constant over the past 7 yr. This behavior is
reminiscent of the late rise of SN1987A, but 1000 times more luminous and much
more rapid to onset. Complex Oxygen line emission in the optical spectrum
further hints at a possible concentric shell or ring-like structure. The
discovery of SN1996cr suggests that a substantial fraction of the closest SNe
observed in the last several decades have occurred in wind-blown bubbles. An
Interplanetary Network position allows us to reject a tentative GRB association
with BATSE 4B960202. [Abridged]


title: On the Origin of Time and the Universe

abstract:
  We present a novel solution to the low entropy and arrow of time puzzles of
the initial state of the Universe. Our approach derives from the physics of a
specific generalization of Matrix theory put forth in earlier work as the basis
for a quantum theory of gravity. The particular dynamical state space of this
theory, the infinite dimensional analogue of the Fubini-Study metric over a
complex non-linear Grassmannian, has recently been studied by Michor and
Mumford. The geodesic distance between any two points on this space is zero.
Here we show that this mathematical result translates to a description of a
hot, zero entropy state and an arrow of time after the Big Bang. This is
modeled as a far from equilibrium, large fluctuation driven, "freezing by
heating" metastable ordered phase transition of a non-linear dissipative
dynamical system.


title:
Respect My Authority! HITS Without Hyperlinks, Utilizing Cluster-Based
  Language Models

abstract:
  We present an approach to improving the precision of an initial document
ranking wherein we utilize cluster information within a graph-based framework.
The main idea is to perform re-ranking based on centrality within bipartite
graphs of documents (on one side) and clusters (on the other side), on the
premise that these are mutually reinforcing entities. Links between entities
are created via consideration of language models induced from them.
  We find that our cluster-document graphs give rise to much better retrieval
performance than previously proposed document-only graphs do. For example,
authority-based re-ranking of documents via a HITS-style cluster-based approach
outperforms a previously-proposed PageRank-inspired algorithm applied to
solely-document graphs. Moreover, we also show that computing authority scores
for clusters constitutes an effective method for identifying clusters
containing a large percentage of relevant documents.


title: The equation asinx+bcosx=c and a family of cyclic Heron quadrilaterals

abstract:
  In the beginning of this paper, we present the general solution to the
trigonometric equation asinx+bcosx=c. After that, we focus on the case when
a^2+b^2=c^2. In this case, the general solution is expressed in terms of the
acute angle theta which satisfies tan(theta)=a/b+c .From the right trianle with
leglengths a and b, and hypotenuse length c, we construct a cyclic
quadrilateral within which the angle theta is illustrated.Then we examine the
case when a,b,and c are integers;and we derive or construct a family of cyclic
Heron quadrilaterals. These are quadrilaterals with integer sidelengths or
edges, integer diagonal lengths, and integer area.Also these quadrilaterals
have their four vertices lying on a circle. The said family of quadrilaterals,
is a three parameter infinite family.


title: Neutrino sector impacts SUSY dark matter

abstract:
  Motivated by the fact that neutrinos are massive, we study the effect of
neutrino Yukawa couplings on neutralino dark matter observables within the
framework of a supersymmetric seesaw. We find that neutrino couplings
significantly affect the neutralino relic density in regions of parameter space
where soft SUSY-breaking slepton masses and/or trilinear couplings are large.
Depending on the size of the couplings, the neutralino relic density spans over
an order of magnitude in the A-funnel, focus point and stop-coannihilation
regions of mSUGRA. We also show that dark matter detection rates can be
modified by up to several orders of magnitude.


title:
Generalized Eulerian-Lagrangian description of Navier-Stokes and
  resistive MHD dynamics

abstract:
  New generalized equations of motion for the Weber-Clebsch potentials that
describe both the Navier-Stokes and MHD dynamics are derived. These depend on a
new parameter, which has dimensions of time for Navier-Stokes and inverse
velocity for MHD. Direct numerical simulations are performed. For
Navier-Stokes, the generalized formalism captures the intense reconnection of
vortices of the Boratav, Pelz and Zabusky flow, in agreement with the previous
study by Ohkitani and Constantin. For MHD, the new formalism is used to detect
magnetic reconnection in several flows: the 3D Arnold, Beltrami and Childress
(ABC) flow and the (2D and 3D) Orszag-Tang vortex. It is concluded that periods
of intense activity in the magnetic enstrophy are correlated with periods of
increasingly frequent resettings. Finally, the positive correlation between the
sharpness of the increase in resetting frequency and the spatial localization
of the reconnection region is discussed.


title: On the Casimir energy for scalar fields with bulk inhomogeneities

abstract:
  We study the field theoretical model of a real scalar field in presence of
spacial inhomogeneity in form of a finite width mirror (material layer). The
interaction of the scalar field with the defect is described with
position-dependent mass term. We calculate the propagator of the theory, the
Casimir energy and the pressure on the boundaries of the layer. We discuss the
renormalization procedure for the model in dimensional regularization.


title:
Does nitrate deposition following astrophysical ionizing radiation
  events pose an additional threat to amphibians?

abstract:
  It is known that amphibians are especially susceptible to the combination of
heightened UVB radiation and increased nitrate concentrations. Various
astrophysical events have been suggested as sources of ionizing radiation that
could pose a threat to life on Earth, through destruction of the ozone layer
and subsequent increase in UVB, followed by deposition of nitrate. In this
study, we investigate whether the nitrate deposition following an ionizing
event is sufficiently large to cause an additional stress beyond that of the
heightened UVB previously considered. We have converted predicted nitrate
depositions to concentration values, utilizing data from the New York State
Department of Environmental Conservation Acid Rain Monitoring Network web site.
Our results show that the increase in nitrate concentration in bodies of water
following the most intense ionization event likely in the last billion years
would not be sufficient to cause a serious additional stress on amphibian
populations and may actually provide some benefit by acting as fertilizer.


title: Maximum Power Efficiency and Criticality in Random Boolean Networks

abstract:
  Random Boolean networks are models of disordered causal systems that can
occur in cells and the biosphere. These are open thermodynamic systems
exhibiting a flow of energy that is dissipated at a finite rate. Life does work
to acquire more energy, then uses the available energy it has gained to perform
more work. It is plausible that natural selection has optimized many biological
systems for power efficiency: useful power generated per unit fuel. In this
letter we begin to investigate these questions for random Boolean networks
using Landauer's erasure principle, which defines a minimum entropy cost for
bit erasure. We show that critical Boolean networks maximize available power
efficiency, which requires that the system have a finite displacement from
equilibrium. Our initial results may extend to more realistic models for cells
and ecosystems.


title: Some Entanglement Features of Highly Entangled Multiqubit States

abstract:
  We explore some basic entanglement features of multiqubit systems that are
relevant for the development of algorithms for searching highly entangled
states. In particular, we compare the behaviours of multiqubit entanglement
measures based (i) on the von Neumann entropy of marginal density matrices and
(ii) on the linear entropy of those matrices.


title:
The dynamical state of A548 from XMM-Newton data: X-ray and radio
  connection

abstract:
  We present a detailed study of the X-ray properties of the galaxy cluster
Abell 548b (z=0.04), using XMM-Newton data, and discuss the connection between
the thermal properties and the presence of two extended relic radio sources
located at the cluster periphery. We wish to analyze the dynamical state of the
cluster and confirm the presence of a major merger. We will discuss the merger
effects on the extended nonthermal emission. From the analysis of the
temperature distribution and of the surface brightness profiles, we find
evidence of a shock in the northern cluster region, just before the location of
the two extended peripheral relics. From the optical analysis, we find that the
cluster galaxies show a large $\sigma_V$, and two components are needed to fit
their velocity distribution. Observational results were compared with a cluster
simulation. The maps of gas temperature and density distribution from the
simulation agree with the observational data in the case of a cluster merger
nearly perpendicular to the plane of the sky and in the state after the maximum
core collapse. We conclude that we are observing a galaxy cluster in a major
merger phase, just after the maximum core collapse. The mass ratio is about
1:2, and the merger collision is nearly perpendicular to the plane of the sky.
A shock is present in the northern cluster region, and it is very likely
responsible for the electron reacceleration and the magnetic field
amplification that will give cause the cluster relics. The relative position of
the shock and the relics is strongly affected by projection effects.


title: Distinction between sequential and direct three-body decays

abstract:
  We discuss the three-body decay mechanisms of many-body resonances.
Sequential decays proceed via two-body configurations after emission of the
third particle. In direct decay all three particles leave simultaneously their
interaction regions. The intermediate paths within the interaction regions are
not observables and only accessible through models. The momentum distributions
carry, apart from polarization, all possible information about decay modes and
resonance structure. In this context we discuss detailed results for the decay
of the $^{9}$Be($5/2^-$) resonance.


title: Josephson physics mediated by the Mott insulating phase

abstract:
  We investigate the static and dynamic properties of bosonic lattice systems
in which condensed and Mott insulating phases co-exist due to the presence of a
spatially-varying potential. We formulate a description of these inhomogeneous
systems and calculate the bulk energy at and near equilibrium. We derive the
explicit form of the Josephson coupling between disjoint superfluid regions
separated by Mott insulating regions. We obtain detailed estimates for the
experimentally-realized case of alternating superfluid and Mott insulating
spherical shells in a radially symmetric parabolically-confined cold atom
system.


title:
The Efficiency of Gravitational Bremsstrahlung Production in the
  Collision of Two Schwarzschild Black Holes

abstract:
  We examine the efficiency of gravitational bremsstrahlung production in the
process of head-on collision of two boosted Schwarzschild black holes. We
constructed initial data for the characteristic initial value problem in
Robinson-Trautman spacetimes, that represent two instantaneously stationary
Schwarzschild black holes in motion towards each other with the same velocity.
The Robinson-Trautman equation was integrated for these initial data using a
numerical code based on the Galerkin method. The final resulting configuration
is a boosted black hole with Bondi mass greater than the sum of the individual
mass of each initial black hole. Two relevant aspects of the process are
presented. The first relates the efficiency $\Delta$ of the energy extraction
by gravitational wave emission to the mass of the final black hole. This
relation is fitted by a distribution function of non-extensive thermostatistics
with entropic parameter $q \simeq 1/2$; the result extends and validates
analysis based on the linearized theory of gravitational wave emission. The
second is a typical bremsstrahlung angular pattern in the early period of
emission at the wave zone, a consequence of the deceleration of the black holes
as they coalesce; this pattern evolves to a quadrupole form for later times.


title: An identity for sums of polylogarithm functions

abstract:
  We derive an identity for certain linear combinations of polylogarithm
functions with negative exponents, which implies relations for linear
combinations of Eulerian numbers. The coefficients of our linear combinations
are related to expanding moments of Satake parameters of holomorphic cuspidal
newforms in terms of the moments of the corresponding Fourier coefficients,
which has applications in analyzing lower order terms in the behavior of zeros
of L-functions near the central point.


title:
Eliminating on the Divergences of the Photon Self - Energy Diagram in
  (2+1) Dimensional Quantum Electrodynamics

abstract:
  The divergence of the photon self - energy diagram in spinor quantum
electrodynamics in $(2+1)$ dimensional space time- $(QED_3)$ is studied by the
Pauli - Villars regularization and dimensional regularization. Results obtained
by two different methods are coincided if the gauge invariant of theory is
considered carefully step by step in these calculations.


title: Site-selective conductance of sidewall functionalized carbon nanotubes

abstract:
  We use DFT to study the effect of molecular adsorbates on the conductance of
metallic carbon nanotubes. The five molecules considered (NO2, NH2, H, COOH,
OH) lead to similar scattering of the electrons. The adsorption of a single
molecule suppresses one of the two available channels of the CNT at low bias
conductance. If more molecules are adsorbed on the same sublattice, the
remaining open channel can be blocked or not, depending on the relative
position of the adsorbates. If a simple geometric condition is fulfilled this
channel is still open, even after adsorbing an arbitrary number of molecules.


title:
Critical behavior of long straight rigid rods on two-dimensional
  lattices: Theory and Monte Carlo simulations

abstract:
  The critical behavior of long straight rigid rods of length $k$ ($k$-mers) on
square and triangular lattices at intermediate density has been studied. A
nematic phase, characterized by a big domain of parallel $k$-mers, was found.
This ordered phase is separated from the isotropic state by a continuous
transition occurring at a intermediate density $\theta_c$. Two analytical
techniques were combined with Monte Carlo simulations to predict the dependence
of $\theta_c$ on $k$, being $\theta_c(k) \propto k^{-1}$. The first involves
simple geometrical arguments, while the second is based on entropy
considerations. Our analysis allowed us also to determine the minimum value of
$k$ ($k_{min}=7$), which allows the formation of a nematic phase on a
triangular lattice.


title: Combinatorial invariants for graph isomorphism problem

abstract:
  Presented approach in polynomial time calculates large number of invariants
for each vertex, which won't change with graph isomorphism and should fully
determine the graph. For example numbers of closed paths of length k for given
starting vertex, what can be though as the diagonal terms of k-th power of the
adjacency matrix. For k=2 we would get degree of verities invariant, higher
describes local topology deeper. Now if two graphs are isomorphic, they have
the same set of such vectors of invariants - we can sort theses vectors
lexicographically and compare them. If they agree, permutations from sorting
allow to reconstruct the isomorphism. I'm presenting arguments that these
invariants should fully determine the graph, but unfortunately I can't prove it
in this moment. This approach can give hope, that maybe P=NP - instead of
checking all instances, we should make arithmetics on these large numbers.


title:
On sensitive dependence on initial conditions and existence of physical
  measure for 3-flows

abstract:
  After reviewing known results on sensitiveness and also on robustness of
attractors together with observations on their proofs, we show that for
attractors of three-dimensional flows, robust chaotic behavior meaning
sensitiveness to initial conditions for the past as well for the future for all
nearby flows) is equivalent to the existence of certain hyperbolic structures.
These structures, in turn, are associated to the existence of physical
measures. In short in low dimensions, robust chaotic behavior for smooth flows
ensures the existence of a physical measure.


title: Lorenz-like chaotic attractors revised

abstract:
  We describe some recent results on the dynamics of singular-hyperbolic (or
Lorenz-like) attractors: attractors in this class are expansive and so
sensitive with respect to initial data; they admit a unique physical measure
whose support is the whole attractor, which is hyperbolic and the equilibrium
state with respect to the center-unstable Jacobian; the hitting time associated
to a geometric Lorenz attractor satisfies a logarithm law; the rate of large
deviations for the physical measure on the ergodic basin of a geometric Lorenz
attractor is exponential.


title: Quantum noise in a nano mechanical Duffing resonator

abstract:
  We determine the small signal gain and noise response of an amplifier based
on the nonlinear response of a quantum nanomechanical resonator. The resonator
is biased in the nonlinear regime by a strong harmonic bias force and we
determine the response to a small additional driving signal detuned with
respect to the bias force.


title: Falling into the Schwarzschild black hole. Important details

abstract:
  The Schwarzschild space is one of the best studied spacetimes and its
exhaustive considerations are easily accessible. Nevertheless, by some reasons
it is still surrounded by a lot of misconceptions, myths, and "paradoxes". In
this pedagogical paper an attempt is made to give a simple (i. e., without
cumbersome calculations), but rigorous consideration to the relevant questions.
I argue that 1) an observer falling into a Schwarzschild black hole will
\emph{not} see "the entire history of the universe" 2) he will \emph{not} cross
the horizon at the speed of light 3) when inside the hole, he will \emph{not}
see the (future) singularity and 4) the latter is \emph{not} "central".


title: A note on generalized concurrences and entanglement detection

abstract:
  We study generalized concurrences as a tool to detect the entanglement of
bipartite quantum systems. By considering the case of 2 X 4 states of rank 2,
we prove that generalized concurrences do not, in general, give a necessary and
sufficient condition of separability. We identify a set of entangled states
which are undetected by this method.


title:
Representation Theory of the Algebra Generated By a Pair of Complex
  Structures

abstract:
  The objective of this paper is to determine the finite dimensional,
indecomposable representations of the algebra that is generated by two complex
structures over the real numbers. Since the generators satisfy relations that
are similar to those of the infinite dihedral group, we give the algebra the
name iD-infinity.


title:
A perturbative approach for the crystal chains with self-consistent
  stochastic reservoirs

abstract:
  We consider the harmonic chain of oscillators with self-consistent stochastic
reservoirs and give a new proof for the finitude of its thermal conductivity in
the steady state. The approach, with involves an integral representation for
the correlations (heat flow)and a perturbative analysis, is quite general and
extendable to the study of anharmonic systems.