title:
Multiphoton Bloch-Siegert shifts and level-splittings in spin-one
  systems

abstract:
  We consider a spin-boson model in which a spin 1 system is coupled to an
oscillator. A unitary transformation is applied which allows a separation of
terms responsible for the Bloch-Siegert shift, and terms responsible for the
level splittings at anticrossings associated with Bloch-Siegert resonances.
When the oscillator is highly excited, the system can maintain resonance for
sequential multiphoton transitions. At lower levels of excitation, resonance
cannot be maintained because energy exchange with the oscillator changes the
level shift. An estimate for the critical excitation level of the oscillator is
developed.


title: Orbital Domain Dynamics in a Doped Manganite

abstract:
  The coupling of multiple degrees of freedom - charge, spin, and lattice - in
manganites has mostly been considered at the microscopic level. However, on
larger length scales, these correlations may be affected by strain and
disorder, which can lead to short range order in these phases and affect the
coupling between them. To better understand these effects, we explore the
dynamics of orbitally ordered domains in a half-doped manganite near the
orbital ordering phase transition. Our results suggest that the domains are
largely static, and exhibit only slow fluctuations near domain boundaries.


title: Implementation of standard testbeds for numerical relativity

abstract:
  We discuss results that have been obtained from the implementation of the
initial round of testbeds for numerical relativity which was proposed in the
first paper of the Apples with Apples Alliance. We present benchmark results
for various codes which provide templates for analyzing the testbeds and to
draw conclusions about various features of the codes. This allows us to sharpen
the initial test specifications, design a new test and add theoretical insight.


title: On The Density Estimation by Super-Parametric Method

abstract:
  The super-parametric density estimators and its related algorism were
suggested by Y. -S. Tsai et al [7]. The number of parameters is unlimited in
the super- parametric estimators and it is a general theory in sense of
unifying or connecting nonparametric and parametric estimators. Before applying
to numerical examples, we can not give any comment of the estimators. In this
paper, we will focus on the implementation, the computer programming, of the
algorism and strategies of choosing window functions. B-splines, Bezier splines
and covering windows are studied as well. According to the criterion of the
convergence conditions for Parzen window, the number of the window functions
shall be, roughly, proportional to the number of samples and so is the number
of the variables. Since the algorism is designed for solving the optimization
of likelihood function, there will be a set of nonlinear equations with a large
number of variables. The results show that algorism suggested by Y. -S. Tsai is
very powerful and effective in the sense of mathematics, that is, the iteration
procedures converge and the rates of convergence are very fast. Also, the
numerical results of different window functions show that the approach of
super-parametric density estimators has ushered a new era of statistics.


title:
Observations of the Optical Afterglow of GRB 050319 : Wind to ISM
  transition in view

abstract:
  The collapse of a massive star is believed to be the most probable progenitor
of a long GRB. Such a star is expected to modify its environment by stellar
wind. The effect of such a circum-stellar wind medium is expected to be seen in
the evolution of a GRB afterglow, but has so far not been conclusively found.
We claim that a signature of wind to constant density medium transition of
circum-burst medium is visible in the afterglow of GRB 050319. Along with the
optical observations of the afterglow of GRB 050319 we present a model for the
multiband afterglow of GRB 050319. We show that the break seen in optical light
curve at $\sim$ 0.02 day could be explained as being due to wind to constant
density medium transition of circum-burst medium, in which case, to our
knowledge, this could be the first ever detection of such a transition at any
given frequency band. Detection of such a transition could also serve as a
confirmation of massive star collapse scenario for GRB progenitors, independent
of supernova signatures.


title: The quantitative behaviour of polynomial orbits on nilmanifolds

abstract:
  A theorem of Leibman asserts that a polynomial orbit
$(g(1),g(2),g(3),\ldots)$ on a nilmanifold $G/\Gamma$ is always equidistributed
in a union of closed sub-nilmanifolds of $G/\Gamma$. In this paper we give a
quantitative version of Leibman's result, describing the uniform distribution
properties of a finite polynomial orbit $(g(1),\ldots,g(N))$ in a nilmanifold.
More specifically we show that there is a factorization $g = \epsilon
g'\gamma$, where $\epsilon(n)$ is "smooth", $\gamma(n)$ is periodic and
"rational", and $(g'(a),g'(a+d),\ldots,g'(a + d(l-1)))$ is uniformly
distributed (up to a specified error $\delta$) inside some subnilmanifold
$G'/\Gamma'$ of $G/\Gamma$, for all sufficiently dense arithmetic progressions
$a,a+d,\ldots,a+d(l-1)$ inside $\{1,..,N\}$.
  Our bounds are uniform in $N$ and are polynomial in the error tolerance
delta. In a subsequent paper we shall use this theorem to establish the Mobius
and Nilsequences conjecture from our earlier paper "Linear equations in
primes".


title: The extragalactic radio-source population at 95 GHz

abstract:
  We have used the Australia Telescope Compact Array (ATCA) at 95GHz to carry
out continuum observations of 130 extragalactic radio sources selected from the
Australia Telescope 20GHz (AT20G) survey. Over 90% of these sources are
detected at 95 GHz, and we use a triple-correlation method to measure
simultaneous 20 and 95 GHz flux densities. We show that the ATCA can measure
95GHz flux densities to ~10% accuracy in a few minutes for sources above
~50mJy.
  The median 20-95GHz spectral index does not vary significantly with flux
density for extragalactic sources with S20>150 mJy. This allows us to estimate
the extragalactic radio source counts at 95GHz by combining our observed
20-95GHz spectral-index distribution with the accurate 20GHz source counts
measured in the AT20G survey. The resulting 95GHz source counts down to 80 mJy
are significantly lower than those found by several previous studies. The main
reason is that most radio sources with flat or rising spectra in the frequency
range 5-20GHz show a spectral turnover between 20 and 95 GHz. As a result,
there are fewer 95GHz sources (by almost a factor of two at 0.1 Jy) than would
be predicted on the basis of extrapolation from the source populations seen in
lower-frequency surveys. We also derive the predicted confusion noise in CMB
surveys at 95GHz and find a value 20-30% lower than previous estimates.
  The 95GHz source population at the flux levels probed by this study is
dominated by QSOs with a median redshift z~1. We find a correlation between
optical magnitude and 95GHz flux density which suggests that many of the
brightest 95 GHz sources are relativistically beamed, with both the optical and
millimetre continuum significantly brightened by Doppler boosting.


title:
Formation of the Galactic globular clusters with He-rich stars in
  low-mass halos virialized at high redshift

abstract:
  Recent observations have reported that the Galactic globular clusters (GCs)
with unusually extended horizontal-branch (EHB) morphologies show a
significantly lower velocity dispersion compared with that of the entire
Galactic GC system. We consider that the observed distinctive kinematics of GCs
with EHB has valuable information on the formation epochs of GCs and
accordingly discuss this observational result based on cosmological N-body
simulations with a model of GC formation. We assume that GCs in galaxies were
initially formed in low-mass halos at high redshifts and we investigate final
kinematics of GCs in their host halos at $z=0$. We find that GCs formed in
halos virialized at z>10 show lower velocity dispersions on average than those
formed at z>6 for halos with GCs at z=0. We thus suggest that the origin of the
observed lower velocity dispersion for the Galactic GCs with EHBs is closely
associated with earlier formation epochs (z>10) of halos initially hosting the
GCs in the course of the Galaxy formation. Considering that the origin of EHBs
can be due to the presence of helium-enhanced second-generation stars in GCs,
we discuss the longstanding second parameter problem of GCs in the context of
different degrees of chemical pollution in GC-forming gas clouds within
low-mass halos virialized at different redshifts.


title:
Control of Goos-Hanchen shift of a light beam via a coherent driving
  field

abstract:
  We present a proposal to manipulate the Goos-Hanchen shift of a light beam
via a coherent control field, which is injected into a cavity configuration
containing the two-level atomic medium. It is found that the lateral shifts of
the reflected and transmitted probe beams can be easily controlled by adjusting
the intensity and detuning of the control field. Using this scheme, the lateral
shift at the fixed incident angle can be enhanced (positive or negative) under
the suitable conditions on the control field, without changing the structure of
the cavity.


title: The shape of hyperbolic Dehn surgery space

abstract:
  In this paper we develop a new theory of infinitesimal harmonic deformations
for compact hyperbolic 3-manifolds with ``tubular boundary''. In particular,
this applies to complements of tubes of radius at least $R_0 =
\arctanh(1/\sqrt{3}) \approx 0.65848$ around the singular set of hyperbolic
cone manifolds, removing the previous restrictions on cone angles.
  We then apply this to obtain a new quantitative version of Thurston's
hyperbolic Dehn surgery theorem, showing that all generalized Dehn surgery
coefficients outside a disc of ``uniform'' size yield hyperbolic structures.
Here the size of a surgery coefficient is measured using the Euclidean metric
on a horospherical cross section to a cusp in the complete hyperbolic metric,
rescaled to have area 1. We also obtain good estimates on the change in
geometry (e.g. volumes and core geodesic lengths) during hyperbolic Dehn
filling.
  This new harmonic deformation theory has also been used by Bromberg and his
coworkers in their proofs of the Bers Density Conjecture for Kleinian groups.


title: Magnetoinductive breathers in magnetic metamaterials

abstract:
  The existence and stability of discrete breathers (DBs) in one-dimensional
and two-dimensional magnetic metamaterials (MMs), which consist of periodic
arrangem ents (arrays) of split-ring resonators (SRRs), is investigated
numerically. We consider different configurations of the SRR arrays, which are
related to the relative orientation of the SRRs in the MM, both in one and two
spatial dimensions. In the latter case we also consider anisotropic MMs. Using
standard numerical methods we construct several types of linearly stable
breather excitations both in Hamiltonian and dissipative MMs (dissipative
breathers). The study of stability in both cases is performed using standard
Floquet analysi s. In both cases we found that the increase of dimensionality
from one to two spatial dimensions does not destroy the DBs, which may also
exist in the case of moderate anisotropy (in two dimensions). In dissipative
MMs, the dynamics is governed by a power balance between the mainly Ohmic
dissipation and driving by an alternating magnetic field. In that case it is
demonstrated that DB excitation locally alters the magnetic response of MMs
from paramagnetic to diamagnetic. Moreover, when the frequency of the applied
field approaches the SRR resonance frequency, the magnetic response of the MM
in the region of the DB excitation may even become negative (extreme
diamagnetic).


title:
Hawking-Page Phase Transition of black Dp-branes and R-charged black
  holes with an IR Cutoff

abstract:
  We show that the confinement-deconfinement phase transition of supersymmetric
Yang-Mills theories with 16 supercharges in various dimensions can be realized
through the Hawking-Page phase transition between the near horizon geometries
of black Dp-branes and BPS Dp-branes by removing a small radius region in the
geometry in order to realize a confinement phase, which generalizes the
Herzog's discussion for the holographic hard-wall AdS/QCD model. Removing a
small radius region in the gravitational dual corresponds to introducing an IR
cutoff in the dual field theory. We also discuss the Hawking-Page phase
transition between thermal $AdS_5$, $AdS_4$, $AdS_7$ spaces and R-charged AdS
black holes coming from the spherical reduction of the decoupling limit of
rotating D3-, M2-, and M5- branes in type IIB supergravity and 11 dimensional
supergravity in grand canonical ensembles, where the IR cutoff also plays a
crucial role in the existence of the phase transition.


title: Rational Approximation for a Quasilinear Parabolic Equation

abstract:
  Approximation theorems, analogous to known results for linear elliptic
equations, are obtained for solutions of the heat equation. Via the Cole-Hopf
transformation, this gives rise to approximation theorems for a nonlinear
parabolic equation, Burgers' equation.


title: Torische Ideale von Flusspolytopen

abstract:
  In dieser Diplomarbeit werden einige Gradschranken f\"ur Erzeugendensysteme
und Gr\"obnerbasen von torischen Idealen von Flusspolytopen bewiesen. Alle
torischen Ideale von Flusspolytopen sind im Grad 3 erzeugt. Glatte
(3x4)-Transportpolytope sind sogar im Grad 2 erzeugt. Die reduzierte
Gr\"obnerbasis eines beliebigen (m \times n)-Transportpolytops bez\"uglich
einer beliebigen umgekehrt lexikographischen Termordnung hat h\"ochstens Grad
mn/2. Wir konstruieren auch ein Beispiel, f\"ur das diese Schranke ann\"ahernd
scharf ist.
  -----
  In this Diplomarbeit (Master's thesis), we prove some degree bounds for
generating sets and Gr\"obner bases of toric ideals of flow polytopes. All
toric ideals of flow polytopes are generated in degree three. Smooth
(3x4)-transportation polytopes are even generated in degree 2. The reduced
Gr\"obner basis of an arbitrary (m \times n)-transportation polytope with
respect to an arbitrary reverse lexikographic term order has at most degree
mn/2. We also construct an example, for which this bound is almost sharp.


title: On Popoviciu type tormulas for generalized restricted partition function

abstract:
  Suppose that $a_1(n),a_2(n),...,a_s(n),m(n)$ are integer-valued polynomials
in $n$ with positive leading coefficients. This paper presents Popoviciu type
formulas for the generalized restricted partition function
$$p_{A(n)}(m(n)):=#\{(x_1,...,x_s)\in \mathbb{Z}^{s}: all x_j\geqslant 0,
x_1a_1(n)+...+x_sa_s(n)=m(n) \}$$ when $s=2$ or 3. In either case, the formula
implies that the function is an integer-valued quasi-polynomial. The main
result is proved by a reciprocity law for a class of fractional part sums and
the theory of generalized Euclidean division.


title: Back-in-time dynamics of the cluster IE 0657-56 (the Bullet System)

abstract:
  We present a simplified dynamical model of the ``Bullet'' system of two
colliding clusters. The model constrains the masses of the system by requiring
that the orbits of the main and sub components satisfy the cosmological initial
conditions of vanishing physical separation a Hubble time ago. This is also
known as the timing argument. The model considers a system embedded in an
over-dense region. We argue that a relative speed of $4500 \rm km/s$ between
the two components is consistent with cosmological conditions if the system is
of a total mass of $2.8\times 10^{15}h^{-1} M_\odot$ is embedded in a region of
a (mild) over-density of 10 times the cosmological background density.
Combining this with the lensing measurements of the projected mass, the model
yields a ratio of 3:1 for the mass of the main relative to that of the
subcomponent. The effect of the background weakens as the relative speed
between the two components is decreased. For relative speeds lower than $\sim
3700\rm km/s$, the timing argument yields masses which are too low to be
consistent with lensing.


title: Black hole as an Information Eraser

abstract:
  We discuss the identity of black hole entropy and show that the first law of
black hole thermodynamics, in the case of a Schwarzschild black hole, can be
derived from Landauer's principle by assuming that the black hole is one of the
most efficient information erasers in systems of a given temperature. The term
"most efficient" implies that minimal energy is required to erase a given
amount of information. We calculate the discrete mass spectra and the entropy
of a Schwarzschild black hole assuming that the black hole processes
information in unit of bits. The black hole entropy acquires a sub-leading
contribution proportional to the logarithm of its mass-squared in addition to
the usual mass-squared term without an artificial cutoff. We also argue that
the minimum of the black hole mass is $\sqrt{\log 2/(8\pi)}M_P$.


title:
4 x 4 matrices in Dirac parametrization: inversion problem and
  determinant

abstract:
  Parametrization of complex 4 x 4 - matrices G in terms of Dirac tensor
parameters (A,B,A_{l},B_{l},F_{kl}) or equivalent four complex 4-vectors
(k,m,n,l) is investigated. In the given parametrization, the problem of
inverting any 4 x 4 matrix G is solved. Expression for determinant of any
matrix G is found: det G = F(k,m,n,l).


title: Ferromagnetic behavior in magnetized plasmas

abstract:
  We consider a low-temperature plasma within a newly developed MHD Fluid
model. In addition to the standard terms, the electron spin, quantum particle
dispersion and degeneracy effects are included. It turns out that the electron
spin properties can give rise to Ferromagnetic behavior in certain regimes. If
additional conditions are fulfilled, a homogenous magnetized plasma can even be
unstable. This happen in the low-temperature high-density regime, when the
magnetic properties associated with the spin can overcome the stabilizing
effects of the thermal and Fermi pressure, to cause a Jeans like instability.


title: Measuring Quark-Gluon-Plasma Thermalization Time with Dileptons

abstract:
  We calculate the medium dilepton yield from a quark-gluon plasma which has a
time-dependent local momentum-space anisotropy. A phenomenological model for
the hard momentum scale, p_hard(tau), and plasma anisotropy parameter, xi(tau),
is constructed which interpolates between free streaming behavior at early
times (tau << tau_iso) and ideal hydrodynamic behavior at late times (tau >>
tau_iso). We show that high-energy dilepton production is sensitive to the
assumed plasma isotropization time, tau_iso, and can therefore be used to
experimentally determine the time of onset for hydrodynamic expansion of a
quark-gluon plasma and the magnitude of expected early-time momentum-space
anisotropies.


title:
Wavefunctions of Auger Electrons Emitted from Copper Atoms: A
  Computational Study

abstract:
  An elaborate least-squares variational technique is proposed for obtaining
improved continuum wavefunctions of Auger electrons emitted from arbitrary
systems the electronic structures of which are determined via one of the
computer codes available. A computer program is developed on the basis of this
technique for calculating the Auger transition rates using the angular momentum
average scheme. The program is employed for investigating the emission of Auger
electrons as a consequence of K- shell ionizations of two configurations of
copper atoms. A comparison is presented between the improved Auger transitions
and the ones determined using conventional Hartree-Fock codes. The results
emphasize the argument that (3p to 3d3d) is the dominant transition in both
configurations of the copper atoms. There is a minimal change in the values of
the Auger transition rates obtained from these configurations. It is
anticipated that the improved continuum wavefunctions provide closer results to
the experimental ones.


title: Emission of K -, L - and M - Auger Electrons from Cu Atoms

abstract:
  The emission of Auger electrons from the K-, L- and M-sheels of two
configurations of copper atoms is investigated in detail within the frame work
of the momentum average technique. Ab initio calculations for the bound state
wavefunctions of the ionized atoms are performed using a Gaussian computer
code. The continuum wavefunctions of the emitted electrons are determined by
employing an effective potential variational approach. Slight differences have
been noticed between the results of both configurations. The transition rates,
energies and widths of all possible Auger electrons are listed in Tables.
Slight differences have been noticed between the results of the two types of
copper atoms.


title: Spherical Model in a Random Field

abstract:
  We investigate the properties of the Gibbs states and thermodynamic
observables of the spherical model in a random field. We show that on the
low-temperature critical line the magnetization of the model is not a
self-averaging observable, but it self-averages conditionally. We also show
that an arbitrarily weak homogeneous boundary field dominates over fluctuations
of the random field once the model transits into a ferromagnetic phase. As a
result, a homogeneous boundary field restores the conventional self-averaging
of thermodynamic observables, like the magnetization and the susceptibility. We
also investigate the effective field created at the sites of the lattice by the
random field, and show that at the critical temperature of the spherical model
the effective field undergoes a transition into a phase with long-range
correlations $\sim r^{4-d}$.


title: Charged particle in the field an electric quadrupole in two dimensions

abstract:
  We obtain analytic solution of the time-independent Schrodinger equation in
two dimensions for a charged particle moving in the field of an electric
quadrupole. The solution is written as a series in terms of special functions
that support a tridiagonal matrix representation for the angular and radial
components of the wave operator. This solution is for all energies, the
discrete (for bound states) as well as the continuous (for scattering states).
The expansion coefficients of the wavefunction are written in terms of
orthogonal polynomials satisfying three-term recursion relations. The charged
particle could become bound to the quadrupole only if its moment exceeds a
certain critical value.


title: Solvable Lie algebras with triangular nilradicals

abstract:
  All finite-dimensional indecomposable solvable Lie algebras $L(n,f)$, having
the triangular algebra T(n) as their nilradical, are constructed. The number of
nonnilpotent elements $f$ in $L(n,f)$ satisfies $1\leq f\leq n-1$ and the
dimension of the Lie algebra is $\dim L(n,f)=f+{1/2}n(n-1)$.


title:
Selfdual Spin 2 Theory in a 2+1 Dimensional Constant Curvature
  Space-Time

abstract:
  The Lagrangian constraint analysis of the selfdual massive spin 2 theory in a
2+1 dimensional flat space-time and its extension to a curved one, are
performed. Demanding consistence of degrees of freedom in the model with
gravitational interaction, gives rise to physical restrictions on non minimal
coupling terms and background. Finally, a constant curvature scenario is
explored, showing the existence of forbidden mass values. Causality in these
spaces is discussed. Aspects related with the construction of the reduced
action and the one-particle exchange amplitude, are noted.


title: Chebyshev approach to quantum systems coupled to a bath

abstract:
  We propose a new concept for the dynamics of a quantum bath, the Chebyshev
space, and a new method based on this concept, the Chebyshev space method. The
Chebyshev space is an abstract vector space that exactly represents the
fermionic or bosonic bath degrees of freedom, without a discretization of the
bath density of states. Relying on Chebyshev expansions the Chebyshev space
representation of a bath has very favorable properties with respect to
extremely precise and efficient calculations of groundstate properties, static
and dynamical correlations, and time-evolution for a great variety of quantum
systems. The aim of the present work is to introduce the Chebyshev space in
detail and to demonstrate the capabilities of the Chebyshev space method.
Although the central idea is derived in full generality the focus is on model
systems coupled to fermionic baths. In particular we address quantum impurity
problems, such as an impurity in a host or a bosonic impurity with a static
barrier, and the motion of a wave packet on a chain coupled to leads. For the
bosonic impurity, the phase transition from a delocalized electron to a
localized polaron in arbitrary dimension is detected. For the wave packet on a
chain, we show how the Chebyshev space method implements different boundary
conditions, including transparent boundary conditions replacing infinite leads.
Furthermore the self-consistent solution of the Holstein model in infinite
dimension is calculated. With the examples we demonstrate how highly accurate
results for system energies, correlation and spectral functions, and
time-dependence of observables are obtained with modest computational effort.


title:
100 Years of dimensional analysis: New steps toward empirical law
  deduction

abstract:
  On the verge of the centenary of dimensional analysis (DA), we present a
generalisation of the theory and a methodology for the discovery of empirical
laws from observational data. It is well known that DA: a) reduces the number
of free parameters, b) guarantees scale invariance through dimensional
homogeneity and c) extracts functional information encoded in the dimensionless
grouping of variables. Less known are the results of Rudolph and co-workers
that DA also gives rise to a new pair of transforms - the similarity transform
(S) that converts physical dimensional data into dimensionless space and its
inverse (S'). Here, we present a new matrix generalisation of the Buckingham
Theorem, made possible by recent developments in the theory of inverse
non-square matrices, and show how the transform pair arises naturally. We
demonstrate that the inverse transform S' is non-unique and how this casts
doubt on scaling relations obtained in cases where observational data has not
been referred to in order to break the degeneracy inherent in transforming back
to dimensional (physical) space. As an example, we show how the underlying
functional form of the Planck Radiation Law can be deduced in only a few lines
using the matrix method and without appealing to first principles; thus
demonstrating the possibility of a priori knowledge discovery; but that
subsequent data analysis is still required in order to identify the exact
causal law. It is hoped that the proof presented here will give theoreticians
confidence to pursue inverse problems in physics using DA.


title: Intermittent relaxation in hierarchical energy landscapes

abstract:
  We numerically simulate a thermalization process in an energy landscape with
hierarchically organized metastable states. The initial configuration is chosen
to have a large energy excess, relative to the thermal equilibrium value at the
running temperature. We show that the initial energy surplus is dissipated in a
series of intermittent bursts, or quakes, whose rate decreases as the inverse
of the age of the system. In addition, one observes energy fluctuations with a
zero centered Gaussian distribution. These pertain to the pseudo equilibrium
dynamics within a single metastable state, and do not contribute to the energy
dissipation. The derivative of the thermal energy with respect to the logarithm
of time is asymptotically constant, and comprises a temperature independent
part, and a part with an Arrhenius temperature dependence. The findings closely
mirror recent numerical simulation results obtained for microscopic glassy
models. For these models, record-sized energy fluctuations have been claimed to
trigger intermittent events during low temperature thermalization. In the
present model record-sized fluctuations are by construction needed to trigger
changes from one metastable state to another. This property thus suffices to
explain the statistical property of intermittent energy flow in complex
metastable systems.


title:
Une adaptation des cartes auto-organisatrices pour des donn\'ees
  d\'ecrites par un tableau de dissimilarit\'es

abstract:
  Many data analysis methods cannot be applied to data that are not represented
by a fixed number of real values, whereas most of real world observations are
not readily available in such a format. Vector based data analysis methods have
therefore to be adapted in order to be used with non standard complex data. A
flexible and general solution for this adaptation is to use a (dis)similarity
measure. Indeed, thanks to expert knowledge on the studied data, it is
generally possible to define a measure that can be used to make pairwise
comparison between observations. General data analysis methods are then
obtained by adapting existing methods to (dis)similarity matrices. In this
article, we propose an adaptation of Kohonen's Self Organizing Map (SOM) to
(dis)similarity data. The proposed algorithm is an adapted version of the
vector based batch SOM. The method is validated on real world data: we provide
an analysis of the usage patterns of the web site of the Institut National de
Recherche en Informatique et Automatique, constructed thanks to web log mining
method.


title: Self-organizing maps and symbolic data

abstract:
  In data analysis new forms of complex data have to be considered like for
example (symbolic data, functional data, web data, trees, SQL query and
multimedia data, ...). In this context classical data analysis for knowledge
discovery based on calculating the center of gravity can not be used because
input are not $\mathbb{R}^p$ vectors. In this paper, we present an application
on real world symbolic data using the self-organizing map. To this end, we
propose an extension of the self-organizing map that can handle symbolic data.


title:
Length-dependent conductance and thermopower in single-molecule
  junctions of dithiolated oligophenylene derivatives

abstract:
  We study theoretically the length dependence of both conductance and
thermopower in metal-molecule-metal junctions made up of dithiolated
oligophenylenes contacted to gold electrodes. We find that while the
conductance decays exponentially with increasing molecular length, the
thermopower increases linearly as suggested by recent experiments. We also
analyze how these transport properties can be tuned with methyl side groups.
Our results can be explained by considering the level shifts due to their
electron-donating character as well as the tilt-angle dependence of conductance
and thermopower. Qualitative features of the substituent effects in our
density-functional calculations are explained using a tight-binding model. In
addition, we observe symmetry-related even-odd transmission channel
degeneracies as a function of molecular length.


title:
Quantum-Mechanically Induced Asymmetry in the Phase Diagrams of
  Spin-Glass Systems

abstract:
  The spin-1/2 quantum Heisenberg model is studied in all spatial dimensions d
by renormalization-group theory. Strongly asymmetric phase diagrams in
temperature and antiferromagnetic bond probability p are obtained in dimensions
d \geq 3. The asymmetry at high temperatures approaching the pure ferromagnetic
and antiferromagnetic systems disappears as d is increased. However, the
asymmetry at low but finite temperatures remains in all dimensions, with the
antiferromagnetic phase receding to the ferromagnetic phase. A
finite-temperature second-order phase boundary directly between the
ferromagnetic and antiferromagnetic phases occurs in d \geq 6, resulting in a
new multicritical point at its meeting with the boundaries to the paramagnetic
phase. In d=3,4,5, a paramagnetic phase reaching zero temperature intervenes
asymmetrically between the ferromagnetic and reentrant antiferromagnetic
phases. There is no spin-glass phase in any dimension.


title: An extension of a result concerning convex geometric graphs

abstract:
  We show a general result known as the Erdos_Sos Conjecture: if
$E(G)>{1/2}(k-1)n$ where $G$ has order $n$ then $G$ contains every tree of
order $k+1$ as a subgraph.


title: A reciprocity map and the two variable p-adic L-function

abstract:
  For primes p greater than 3, we propose a conjecture that relates the values
of cup products in the Galois cohomology of the maximal unramified outside p
extension of a cyclotomic field on cyclotomic p-units to the values of p-adic
L-functions of cuspidal eigenforms that satisfy mod p congruences with
Eisenstein series. Passing up the cyclotomic and Hida towers, we construct an
isomorphism of certain spaces that allows us to compare the value of a
reciprocity map on a particular norm compatible system of p-units to what is
essentially the two-variable p-adic L-function of Mazur and Kitagawa.


title: Classical elliptic current algebras

abstract:
  In this paper we discuss classical elliptic current algebras and show that
there are two different choices of commutative test function algebras on a
complex torus leading to two different elliptic current algebras. Quantization
of these classical current algebras give rise to two classes of quantized
dynamical quasi-Hopf current algebras studied by Enriquez-Felder-Rubtsov and
Arnaudon-Buffenoir-Ragoucy-Roche-Jimbo-Konno-Odake-Shiraishi. Different
degenerations of the classical elliptic algebras are considered. They yield
different versions of rational and trigonometric current algebras. We also
review the averaging method of Faddeev-Reshetikhin, which allows to restore
elliptic algebras from the trigonometric ones.


title: Noncommutative del Pezzo surfaces and Calabi-Yau algebras

abstract:
  The hypersurface in a 3-dimensional vector space with an isolated
quasi-homogeneous elliptic singularity of type E_r,r=6,7,8, has a natural
Poisson structure. We show that the family of del Pezzo surfaces of the
corresponding type E_r provides a semiuniversal Poisson deformation of that
Poisson structure.
  We also construct a deformation-quantization of the coordinate ring of such a
del Pezzo surface. To this end, we first deform the polynomial algebra C[x,y,z]
to a noncommutative algebra with generators x,y,z and the following 3 relations
(where [u,v]_t = uv- t.vu):
  [x,y]_t=F_1(z),
  [y,z]_t=F_2(x),
  [z,x]_t=F_3(y).
  This gives a family of Calabi-Yau algebras A(F) parametrized by a complex
number t and a triple F=(F_1,F_2,F_3), of polynomials in one variable of
specifically chosen degrees.
  Our quantization of the coordinate ring of a del Pezzo surface is provided by
noncommutative algebras of the form A(F)/(g) where (g) stands for the ideal of
A(F) generated by a central element g, which generates the center of the
algebra A(F) if F is generic enough.


title:
MCBs versus Fuses in Low-Voltage Applications: Critical Analysis Using
  the 3-AND Convergence Classifier

abstract:
  The protection of any electrical installation is one of the most important
considerations in the field of electrical engineering. The electrical
installation should be protected against hazards such as overload current and
short circuit current conditions. The protection devices studied in this paper
are the Miniature Circuit Breaker (MCB) and the High Rupturing Capacity (HRC)
Fuse. Using a new tool known as the 3-AND Convergence Classifier, it was
observed that the MCB is the most reliable in terms of offering protection
against the damage caused by overload currents and the destruction caused by
short circuit currents.


title: Ubiquitous systems and metric number theory

abstract:
  We investigate the size and large intersection properties of
$$E_{t}=\{x\in\R^d \:|\: \|x-k-x_{i}\|<{r_{i}}^t\text{for infinitely
many}(i,k)\in I^{\mu,\alpha}\times\Z^d\},$$ where $d\in\N$, $t\geq 1$, $I$ is a
denumerable set, $(x_{i},r_{i})_{i\in I}$ is a family in $[0,1]^d\times
(0,\infty)$ and $I^{\mu,\alpha}$ denotes the set of all $i\in I$ such that the
$\mu$-mass of the ball with center $x_{i}$ and radius $r_{i}$ behaves as
${r_{i}}^\alpha$ for a given Borel measure $\mu$ and a given $\alpha>0$. We
establish that the set $E_{t}$ belongs to the class $\grint^h(\R^d)$ of sets
with large intersection with respect to a certain gauge function $h$, provided
that $(x_{i},r_{i})_{i\in I}$ is a heterogeneous ubiquitous system with respect
to $\mu$. In particular, $E_{t}$ has infinite Hausdorff $g$-measure for every
gauge function $g$ that increases faster than $h$ in a neighborhood of zero. We
also give several applications to metric number theory.


title: Singularity sets of Levy processes

abstract:
  We completely describe the size and large intersection properties of the
Holder singularity sets of Levy processes. We also study the set of times at
which a given function cannot be a modulus of continuity of a Levy process. The
Holder singularity sets of the sample paths of certain random wavelet series
are investigated as well.


title: Random wavelet series based on a tree-indexed Markov chain

abstract:
  We study the global and local regularity properties of random wavelet series
whose coefficients exhibit correlations given by a tree-indexed Markov chain.
We determine the law of the spectrum of singularities of these series, thereby
performing their multifractal analysis. We also show that almost every sample
path displays an oscillating singularity at almost every point and that the
points at which a sample path has at most a given Holder exponent form a set
with large intersection.


title: Random fractals and tree-indexed Markov chains

abstract:
  We study the size properties of a general model of fractal sets that are
based on a tree-indexed family of random compacts and a tree-indexed Markov
chain. These fractals may be regarded as a generalization of those resulting
from the Moran-like deterministic or random recursive constructions considered
by various authors. Among other applications, we consider various extensions of
Mandelbrot's fractal percolation process.


title: Liouville theorems for the Navier-Stokes equations and applications

abstract:
  We study bounded ancient solutions of the Navier-Stokes equations. These are
the solutions which are defined for all past time. In two space dimensions we
prove that such solutions are either constant or functions of time only,
depending on the exact definition of admissible solutions. The general three
dimensional problem seems to be out of reach of existing techniques, but
partial results can be obtained in the case of axi-symmetric solutions. We
apply these results to some scenarios of potential singularity formation for
axi-symmetric solutions.


title:
Cooperative Multiplexing in a Half Duplex Relay Network: Performance and
  Constraints

abstract:
  Previous work on relay networks has concentrated primarily on the diversity
benefits of such techniques. This paper explores the possibility of also
obtaining multiplexing gain in a relay network, while retaining diversity gain.
Specifically, consider a network in which a single source node is equipped with
one antenna and a destination is equipped with two antennas. It is shown that,
in certain scenarios, by adding a relay with two antennas and using a
successive relaying protocol, the diversity multiplexing tradeoff performance
of the network can be lower bounded by that of a 2 by 2 MIMO channel, when the
decode-and-forward protocol is applied at the relay. A distributed D-BLAST
architecture is developed, in which parallel channel coding is applied to
achieve this tradeoff. A space-time coding strategy, which can bring a maximal
multiplexing gain of more than one, is also derived for this scenario. As will
be shown, while this space-time coding strategy exploits maximal diversity for
a small multiplexing gain, the proposed successive relaying scheme offers a
significant performance advantage for higher data rate transmission. In
addition to the specific results shown here, these ideas open a new direction
for exploiting the benefits of wireless relay networks.


title:
Hurwitz numbers for regular coverings of surfaces by seamed surfaces and
  Cardy-Frobenius algebras of finite groups

abstract:
  Analogue of classical Hurwitz numbers is defined in the work for regular
coverings of surfaces with marked points by seamed surfaces. Class of surfaces
includes surfaces of any genus and orientability, with or without boundaries;
coverings may have certain singularities over the boundary and marked points.
Seamed surfaces introduced earlier are not actually surfaces. A simple example
of seamed surface is book-like seamed surface: several rectangles glued by
edges like sheets in a book.
  We prove that Hurwitz numbers for a class of regular coverings with action of
fixed finite group $G$ on cover space such that stabilizers of generic points
are conjugated to a fixed subgroup $K\subset G$ defines a new example of Klein
Topological Field Theory (KTFT). It is known that KTFTs are in one-to-one
correspondence with certain class of algebras, called in the work
Cardy-Frobenius algebras. We constructed a wide class of Cardy-Frobenius
algebras, including particularly all Hecke algebras for finite groups.
Cardy-Frobenius algebras corresponding to regular coverings of surfaces by
seamed surfaces are described in terms of group $G$ and its subgroups. As a
result, we give an algebraic formula for introduced Hurwitz numbers.


title: Time and length scales of autocrine signals in three dimensions

abstract:
  A model of autocrine signaling in cultures of suspended cells is developed on
the basis of the effective medium approximation. The fraction of autocrine
ligands, the mean and distribution of distances traveled by paracrine ligands
before binding, as well as the mean and distribution of the ligand lifetime are
derived. Interferon signaling by dendritic immune cells is considered as an
illustration.


title: Fibonacci schemes of fault-tolerant quantum computation

abstract:
  The threshold estimate derived in previous versions of this paper was
incorrect; this note explains the flaw. A new proof is discussed in
arXiv:0809.5063.


title:
Periodic States, Local Effects and Coexistence in the BML Traffic Jam
  Model

abstract:
  The Biham-Middleton-Levine model (BML) is simple lattice model of traffic
flow, self-organization and jamming. Rather than a sharp phase transition
between free-flow and jammed, it was recently shown that there is a region
where stable intermediate states exist, with details dependent on the aspect
ratio of the underlying lattice. Here we investigate square aspect ratios,
focusing on the region where random, disordered intermediate (DI) states and
conventional global jam (GJ) states coexist, and show that DI states dominate
for some densities and timescales. Moreover, we show that periodic intermediate
(PI) states can also coexist. PI states converge to periodic limit cycles with
short recurrence times and were previously conjectured to arise from
idiosyncrasies of relatively prime aspect ratios. The observed coexistence of
DI, PI and GJ states shows that global parameters, density together with aspect
ratio, are not sufficient to determine the full jamming outcome. We investigate
additional features that lead towards jamming and show that a strategic
perturbation of a few selected bits can change the nature of the flow,
nucleating a global jam.


title: Interactions of Hermitian and non-Hermitian Hamiltonians

abstract:
  The coupling of non-Hermitian PT-symmetric Hamiltonians to standard Hermitian
Hamiltonians, each of which individually has a real energy spectrum, is
explored by means of a number of soluble models. It is found that in all cases
the energy remains real for small values of the coupling constant, but becomes
complex if the coupling becomes stronger than some critical value. For a
quadratic non-Hermitian PT-symmetric Hamiltonian coupled to an arbitrary real
Hermitian PT-symmetric Hamiltonian, the reality of the ground-state energy for
small enough coupling constant is established up to second order in
perturbation theory.


title:
Noise enhanced persistence in a biochemical regulatory network with
  feedback control

abstract:
  We find that discrete noise of inhibiting (signal) molecules can greatly
delay the extinction of plasmids in a plasmid replication system: a
prototypical biochemical regulatory network. We calculate the probability
distribution of the metastable state of the plasmids and show on this example
that the reaction rate equations may fail in predicting the average number of
regulated molecules even when this number is large, and the time is much
shorter than the mean extinction time.


title: Toroidal metamaterial

abstract:
  It is shown that a new type of metamaterial, a 3D-array of toroidal
solenoids, displays a significant toroidal response that can be readily
measured. This is in sharp contrast to materials that exist in nature, where
the toroidal component is weak and hardly measurable. The existence of an
optimal configuration, maximizing the interaction with an external
electromagnetic field, is demonstrated. In addition, it is found that a
characteristic feature of the magnetic toroidal response is its strong
dependence on the background dielectric permittivity of the host material,
which suggests possible applications. Negative refraction and backward waves
exist in a composite toroidal metamaterial, consisting of an array of wires and
an array of toroidal solenoids.


title: Kraus decomposition for chaotic environments

abstract:
  We consider a system interacting with a chaotic thermodynamic bath. We derive
an explicit and exact Kraus operator sum representation (OSR) for the open
system reduced density. The OSR preserves the Hermiticity, complete positivity
and norm. We show that it is useful as a numerical tool by testing it against
exact results for a qubit interacting with an isolated flawed quantum computer.
We also discuss some interesting qualitative aspects of the OSR.


title:
Einstein Gravity as a Nonholonomic Almost Kahler Geometry,
  Lagrange-Finsler Variables, and Deformation Quantization

abstract:
  A geometric procedure is elaborated for transforming (pseudo) Riemanian
metrics and connections into canonical geometric objects (metric and nonlinear
and linear connections) for effective Lagrange, or Finsler, geometries which,
in their turn, can be equivalently represented as almost Kahler spaces. This
allows us to formulate an approach to quantum gravity following standard
methods of deformation quantization. Such constructions are performed not on
tangent bundles, as in usual Finsler geometry, but on spacetimes enabled with
nonholonomic distributions defining 2+2 splitting with associate nonlinear
connection structure. We also show how the Einstein equations can be redefined
in terms of Lagrange-Finsler variables and corresponding almost symplectic
structures and encoded into the zero-degree cohomology coefficient for a
quantum model of Einstein manifolds.


title:
Inelastic effects in molecular junction transport: Scattering and
  self-consistent calculations for the Seebeck coefficient

abstract:
  The influence of molecular vibration on the Seebeck coefficient is studied
within a simple model. Results of a scattering theory approach are compared to
those of a full self-consistent non-equilibrium Green's function scheme. We
show, for a reasonable choice of parameters, that inelastic effects have
non-negligible influence on the resulting Seebeck coefficient for the junction.
We note that the scattering theory approach may fail both quantitatively and
qualitatively. Results of calculation with reasonable parameters are in good
agreement with recent measurements [P. Reddy et al., Science 315, 1568 (2007)]


title: Quantum correlations for arbitrarily high-dimensional Bell inequality

abstract:
  We analyze the correlation structure of bipartite arbitrary-dimensional Bell
inequalities via novel conditions of correlations in terms of differences of
joint probabilities called correlators. The conditions of correlations are
shown to be necessary for the multi-level Bell state. In particular, we find
that the bipartite arbitrary-dimensional Bell-type inequalities introduced by
Collins-Gisin-Linden-Massar-Popescu [Phys. Rev. Lett. 88, 040404 (2002)] and
Son-Lee-Kim [Phys. Rev. Lett. 96, 060406 (2006)] are composed of correlators,
and we reveal that the maximal violations by the Bell state just fit the
conditions of quantum correlations. Correlators can be considered as essential
elements of Bell inequalities.


title: Overview and Status of the CMS Silicon Strip Tracker

abstract:
  The CMS experiment at the LHC features the largest Silicon Strip Detector
ever built. The impact of the operating conditions and physics requirements on
the design choices of the CMS Silicon Tracker is reviewed. The readiness of the
Silicon Strip Tracker for the tentatively scheduled CMS commissioning in Summer
2008 is briefly described.


title: On orbit closures for infinite type quivers

abstract:
  For the Kronecker quiver, Zwara has found an example of a representation
whose orbit closure is neither unibranch nor Cohen-Macaulay. In this note, we
explain how to extend this example to all infinite type quivers without
oriented cycles.


title:
Search for Pulsar Wind Nebula Associations of Unidentified TeV Gamma-Ray
  Sources

abstract:
  Many of the recently discovered TeV gamma-ray sources are associated with
pulsar wind nebulae (PWNe). In fact, they represent the most populous class of
Galactic sources at TeV energies. In addition, HESS has also discovered, in a
survey of the Galactic plane, a population of TeV gamma-ray sources that are
still without definitive counterparts at longer wavelengths. For a number of
these sources, a pulsar is an evident association, which is often located
within an extended region of the TeV gamma-ray emission. These particular HESS
sources are promising candidates for yet not resolved pulsar wind nebulae. Here
we have undertaken a systematic search for X-ray counterparts of the sources,
using the archival Chandra data, within the spatial bounds of the unidentified
HESS sources. A number of X-ray sources have been detected in the Chandra
fields. Two of them, CXOU J161729.3-505512 and CXOU J170252.4-412848, are of a
special interest because of their excellent positional coincidence with the
pulsars PSR J1617-5055 and PSR J1702-4128, respectively. The first source is
extended, with a bright core of 2.6 arcsec (FWHM) in radius but the emission
can be seen up to roughly 20 arcsec. The second one is much fainter and
detected only with marginal significance (4.6 sigma). It might also be slightly
extended, although the situation is quite uncertain due to very limited
statistics. The analysis of the archival Chandra data for a middle-aged pulsar
(PSR J1913+1011) does not reveal any statistically significant excess at and
around the position of the pulsar or the center of gravity of its plausible TeV
gamma-ray counterpart (HESS J1912+101). We discuss the implications of the
results.


title: Lecture Notes on Equivariant Cohomology

abstract:
  These are the lecture notes for the introductory graduate course I taught at
Yale during Spring 2007. I mostly followed [GS], [BGV], [AB], [Par2], and there
are no original results in these notes.


title:
Why understanding neutrino interactions is important for oscillation
  physics

abstract:
  Uncertainties in knowledge of neutrino interactions directly impact the
ability to measure the parameters of neutrino oscillation. Experiments which
make use of differing technologies and neutrino beams are sensitive to
different uncertainties. Several experimental and theoretical issues are
reviewed.


title: Bosonization approach to the mixed-valence two-channel Kondo problem

abstract:
  We present in detail the bosonization-refermionization solution of the
anisotropic version of the two-channel Anderson model at a particular manifold
in the space of parameters of the theory, where we establish an equivalence
with a Fermi-Majorana bi-resonant level model. The correspondence is rigorously
proved by explicitly constructing the new fermionic fields and Klein factors in
terms of the original ones and showing that the commutation properties between
original and new Klein factors are of semionic type. We also demonstrate that
the fixed points associated to the solvable manifold are renormalization-group
stable and generic, and therefore representative of the physics of the original
model. The simplicity of the solution found, allows for the computation of the
full set of thermodynamic quantities. In particular, we compute the entropy,
occupation and magnetization of the impurity as functions of temperature, and
identify the different physical energy scales. In absence of external fields,
two energy scales appear and, as the temperature goes to zero, a non-trivial
residual entropy indicates that the model approaches a universal line of fixed
points of non-Fermi liquid type. An external field, even if small, introduces a
third energy scale and causes the quenching of the impurity entropy to zero,
taking the system to a corresponding Fermi-liquid fixed point.


title:
Two-orbital Systems with Crystal Field Splitting and Interorbital
  Hopping

abstract:
  The nondegenerate two-orbital Hubbard model is studied within the dynamic
mean-field theory to reveal the influence of two important factors, i.e.
crystal field splitting and interorbital hopping, on orbital selective Mott
transition (OSMT) and realistic compound Ca$_{2-x}$Sr$_{x}$RuO$_{4}$. A
distinctive feature of the optical conductivity of the two nondegenerate bands
is found in OSMT phase, where the metallic character of the wide band is
indicated by a nonzero Drude peak, while the insulating narrow band has its
Drude peak drop to zero in the mean time. We also find that the OSMT regime
expands profoundly with the increase of interorbital hopping integrals. On the
contrary, it is shown that large and negative level splitting of the two
orbitals diminishes the OSMT regime completely. Applying the present findings
to compound Ca$_{2-x}$Sr$_{x}$RuO$_{4}$, we demonstrate that in the doping
region from $x=0.2$ to 2.0, the negative level splitting is unfavorable to the
OSMT phase.


title: Thermodynamics of charged topological dilaton black holes

abstract:
  A class of $(n+1)$-dimensional topological black hole solutions in
Einstein-Maxwell-dilaton theory with Liouville-type potentials for the dilaton
field is presented. In these spacetimes, black hole horizon and cosmological
horizon can be an $(n-1)$-dimensional positive, zero or negative constant
curvature hypersurface. Because of the presence of the dilaton field, these
topological black holes are neither asymptotically flat nor (anti)-de Sitter.
We calculate the charge, mass, temperature, entropy and electric potential of
these solutions. We also analyze thermodynamics of these topological black
holes and disclose the effect of the dilaton field on the thermal stability of
the solutions.


title: On maps which preserve equality of distance in F-spaces

abstract:
  In order to generalize the results of Mazur-Ulam and Vogt, we shall prove
that any map T which preserves equality of distance with T(0)=0 between two
F-spaces without surjective condition is linear. Then, as a special case linear
isometries are characterized through a simple property of their range.


title:
Constraining properties of rapidly rotating neutron stars using data
  from heavy-ion collisions

abstract:
  Properties, structure, and thermal evolution of neutron stars are determined
by the equation of state of stellar matter. Recent data on isospin-diffusion
and isoscaling in heavy-ion collisions at intermediate energies as well as the
size of neutron skin in $^{208}Pb$ have constrained considerably the density
dependence of the nuclear symmetry energy and, in turn, the equation of state
of neutron-rich nucleonic matter. These constraints could provide useful
information about the global properties of rapidly rotating neutron stars.
Models of rapidly rotating neutron stars are constructed applying several
nucleonic equations of state. Particular emphasis is placed on configurations
rotating rigidly at $716$ and $1122Hz$. The range of allowed hydrostatic
equilibrium solutions is determined and tested for stability. The effect of
rotation on the internal composition and thermal properties of neutron stars is
also examined. At a given rotational frequency, each equation of state yields a
range of possible neutron stars configurations restricted by the Keplerian
(mass-shedding) limit, corresponding to the maximal circumferential radius, and
the limit due to the onset of instabilities with respect to axial-symmetric
perturbations, corresponding to the minimal equatorial radius of a stable
neutron star model. We show that the mass of a neutron star rotating uniformly
at $1122Hz$ is between $1.7$ and $2.1M_{\sun}$. Central stellar density and
proton fraction decrease with increasing rotational frequency with respect to
static models, and depending on the exact stellar mass and angular velocity,
can drop below the Direct Urca threshold thus closing the fast cooling channel.


title:
Numerical simulations of the type III migration:I. Disc model and
  convergence tests

abstract:
  We investigate the fast (type III) migration regime of high-mass protoplanets
orbiting in protoplanetary disks. This type of migration is dominated by
corotational torques. We study the details of flow structure in the planet's
vicinity, the dependence of migration rate on the adopted disc model, and the
numerical convergence of models (independence of certain numerical parameters
such as gravitational softening). We use two-dimensional hydrodynamical
simulations with adaptive mesh refinement,based on the FLASH code with improved
time-stepping scheme. We perform global disk simulations with sufficient
resolution close to the planet, which is allowed to freely move throughout the
grid. We employ a new type of equation of state in which the gas temperature
depends on both the distance to the star and planet, and a simplified
correction for self-gravity of the circumplanetary gas. We find that the
migration rate in the type III migration regime depends strongly on the gas
dynamics inside the Hill sphere (Roche lobe of the planet) which, in turn, is
sensitive to the aspect ratio of the circumplanetary disc. Furthermore,
corrections due to the gas self-gravity are necessary to reduce numerical
artifacts that act against rapid planet migration. Reliable numerical studies
of Type III migration thus require consideration of both the thermal andthe
self-gravity corrections, as well as a sufficient spatial resolution and the
calculation of disk-planet attraction both inside and outside the Hill sphere.
With this proviso, we find Type III migration to be a robust mode of migration,
astrophysically promising because of a speed much faster than in the previously
studied modes of migration.


title: Noncommutativity, generalized uncertainty principle and FRW cosmology

abstract:
  We consider the effects of noncommutativity and the generalized uncertainty
principle on the FRW cosmology with a scalar field. We show that, the
cosmological constant problem and removability of initial curvature singularity
find natural solutions in this scenarios.


title:
Sequestration of noble gases by H3+ in protoplanetary disks and outer
  solar system composition

abstract:
  We study the efficiency of the noble gases sequestration by the ion H3+ in
the form of XH3+ complexes (with X = argon, krypton or xenon) in gas phase
conditions similar to those encountered during the cooling of protoplanetary
disks, at the epoch of icy planetesimals formation. We show that XH3+ complexes
form very stable structures in the gas phase and that their binding energies
are much higher than those involved in the structures of X-H2O hydrates or pure
X-X condensates. This implies that, in presence of H3+ ions, argon, krypton or
xenon are likely to remain sequestrated in the form of XH3+ complexes embedded
in the gas phase rather than forming ices during the cooling of protoplanetary
disks. The amount of the deficiency depends on how much H3+ is available and
efficient in capturing noble gases. In the dense gas of the mid-plane of solar
nebula, H3+ is formed by the ionization of H2 from energetic particles, as
those in cosmic rays or those ejected by the young Sun. Even using the largest
estimate of the cosmic rays ionization rate, we compute that the H3+ abundance
is two and three orders of magnitude lower than the xenon and krypton
abundance, respectively. Estimating the ionization induced by the young Sun, on
the other hand, is very uncertain but leaves the possibility to have enough H3+
to make krypton and xenon trapping efficent. Finally, additional source of H3+
formation may be provided by the presence of a nearby supernova, as discussed
in the literature. Recent solar system observations show a deficiency of Ar,
and, even more, of Kr and Xe in Titan and in comets. In this article, we
consider the possibility that this deficiency is caused by the afore-mentioned
process, namely trapping of those noble gases by H3+ ions in the solar nebula.


title: Laterally coupled and field-induced quantum Hall systems

abstract:
  A quantum Hall system which is divided into two laterally coupled subsystems
by means of a tunneling barrier exhibits a complex Landau level dispersion.
Magnetotunneling spectroscopy is employed to investigate the small energy gaps
which separate subsequent Landau bands. The control on the Fermi level permits
to trace the anticrossings for varying magnetic fields. The band structure
calculation predicts a magnetic shift of the band gaps on the scale of the
cyclotron energy. This effect is confirmed experimentally by a displacement of
the conductance peaks on the axis of the filling factor. Tunneling centers
within the barrier are responsible for quantum interferences between opposite
edge channels. Due to the disorder potential, the corresponding Aharonov-Bohm
interferometers generate additional long-period and irregular conductance
features. In the regime of strong localization, conductance fluctuations occur
at small magnetic fields before the onset of the regular Landau oscillations.
The Landau dispersion is obtained by a dedicated algorithm which solves the
Schroedinger equation exactly for a single electron residing in a quantum Hall
system with an arbitrary unidirectional, threefold staircase potential.


title: Dimer percolation and jamming on simple cubic lattice

abstract:
  We consider site percolation of dimers (``neadles'') on simple cubic lattice.
The percolation threshold is estimated as $p_c^\text{perc} \approx 0.2555 \pm
0.0001$. The jamming threshold is estimated as $p_c^\text{jamm} = 0.799 \pm
0.002$.


title: Exact Quantum Search by Parallel Unitary Discrimination Schemes

abstract:
  We study the unsorted database search problem with items $N$ from the
viewpoint of unitary discrimination. Instead of considering the famous
$O(\sqrt{N})$ Grover's the bounded-error algorithm for the original problem, we
seek for the results about the exact algorithms, i.e. the ones succeed with
certainty. Under the standard oracle model $\sum_j (-1)^{\delta_{\tau j}}|j><
j|$, we demonstrate a tight lower bound ${2/3}N+o(N)$ of the number of queries
for any parallel scheme with unentangled input states. With the assistance of
entanglement, we obtain a general lower bound ${1/2}(N-\sqrt{N})$. We provide
concrete examples to illustrate our results. In particular, we show that the
case of N=6 can be solved exactly with only two queries by using a bipartite
entangled input state. Our results indicate that in the standard oracle model
the complexity of exact quantum search with one unique solution can be strictly
less than that of the calculation of OR function.


title: \ell-adic class field theory for regular local rings

abstract:
  In this paper, we prove the $\ell$-adic abelian class field theory for
henselian regular local rings of equi-characteristic assuming the surjectivity
of Galois symbol maps, which is a $\ell$-adic variant of a result of Matsumi
[13].


title: A Functorial Approach to the Infinitesimal Theory of Groupoids

abstract:
  Lie algebroids are by no means natural as an infinitesimal counterpart of
groupoids. In this paper we propose a functorial construction called Nishimura
algebroids for an infinitesimal counterpart of groupoids. Nishimura algebroids,
intended for differential geometry, are of the same vein as Lawvere's
functorial notion of algebraic theory and Ehresmann's functorial notion of
theory called sketches. We study totally intransitive Nishimura algebroids in
detail. Finally we show that Nishimura algebroids naturally give rise to Lie
algebroids.


title: Investments in Random Environments

abstract:
  We present analytical investigations of a multiplicative stochastic process
that models a simple investor dynamics in a random environment. The dynamics of
the investor's budget, $x(t)$, depends on the stochasticity of the return on
investment, $r(t)$, for which different model assumptions are discussed. The
fat-tail distribution of the budget is investigated and compared with
theoretical predictions. Weare mainly interested in the most probable value
$x_mp$ of the budget that reaches a constant value over time. Based on an
analytical investigation of the dynamics, we are able to predict $x_mp^stat$.
We find a scaling law that relates the most probable value to the
characteristic parameters describing the stochastic process. Our analytical
results are confirmed by stochastic computer simulations that show a very good
agreement with the predictions.


title:
Turning the Quantum Group Invariant XXZ Spin-Chain Hermitian: A
  Conjecture on the Invariant Product

abstract:
  This is a continuation of a previous joint work with Robert Weston on the
quantum group invariant XXZ spin-chain (math-ph/0703085). The previous results
on quasi-Hermiticity of this integrable model are briefly reviewed and then
connected with a new construction of an inner product with respect to which the
Hamiltonian and the representation of the Temperley-Lieb algebra become
Hermitian. The approach is purely algebraic, one starts with the definition of
a positive functional over the Temperley-Lieb algebra whose values can be
computed graphically. Employing the Gel'fand-Naimark-Segal (GNS) construction
for C*-algebras a self-adjoint representation of the Temperley-Lieb algebra is
constructed when the deformation parameter q lies in a special section of the
unit circle. The main conjecture of the paper is the unitary equivalence of
this GNS representation with the representation obtained in the previous paper
employing the ideas of PT-symmetry and quasi-Hermiticity. An explicit example
is presented.


title: Quantum dynamics and entanglement of spins on a square lattice

abstract:
  Bulk magnetism in solids is fundamentally quantum mechanical in nature. Yet
in many situations, including our everyday encounters with magnetic materials,
quantum effects are masked, and it often suffices to think of magnetism in
terms of the interaction between classical dipole moments. Whereas this
intuition generally holds for ferromagnets, even as the size of the magnetic
moment is reduced to that of a single electron spin (the quantum limit), it
breaks down spectacularly for antiferromagnets, particularly in low dimensions.
Considerable theoretical and experimental progress has been made in
understanding quantum effects in one-dimensional quantum antiferromagnets, but
a complete experimental description of even simple two-dimensional
antiferromagnets is lacking. Here we describe a comprehensive set of neutron
scattering measurements that reveal a non-spin-wave continuum and strong
quantum effects, suggesting entanglement of spins at short distances in the
simplest of all two-dimensional quantum antiferromagnets, the square lattice
Heisenberg system.


title: The star pile in Abell 545

abstract:
  Context:Struble (1988) found what appeared to be a cD halo without cD galaxy
in the center of the galaxy cluster Abell 545. This remarkable feature has been
passed almost unnoticed for nearly twenty years.
  Aims:Our goal is to review Struble's claim by providing a first (preliminary)
photometric and spectroscopic analysis of this ''star pile''.
  Methods:Based on archival VLT-images and long-slit spectra obtained with
Gemini-GMOS, we describe the photometric structure and measure the redshift of
the star pile and of the central galaxy.
  Results:The star pile is indeed associated with Abell 545. Its velocity is
higher by about 1300 km/s than that of the central object. The spectra indicate
an old, presumably metal-rich population. Its brightness profile is much
shallower than that of typical cD-galaxies.
  Conclusions:The formation history and the dynamical status of the star pile
remain elusive, until high S/N spectra and a dynamical analysis of the galaxy
cluster itself become available. We suggest that the star pile might provide an
interesting test of the Cold Dark Matter paradigm.


title:
Full calculation of clumpiness boost factors for antimatter cosmic rays
  in the light of Lambda-CDM N-body simulation results

abstract:
  Anti-proton and positron Galactic cosmic ray spectra are among the key
targets for indirect detection of dark matter. The boost factors, corresponding
to an enhancement of the signal and linked to the clumpiness properties of the
dark matter distribution, have been taken as high as thousands in the past. The
dramatic impact of these boost factors for indirect detection of antiparticles,
for instance with the PAMELA satellite or the coming AMS-02 experiment, asks
for their detailed calculation. We take into account the results of high
resolution N-body dark matter simulations to calculate the most likely energy
dependent boost factors linked to the cosmic ray propagation properties, for
anti-protons and positrons. Starting from the mass and space distributions of
sub-halos, the anti-proton and positron propagators are used to calculate the
mean value and the variance of the boost factor for the primary fluxes. We take
advantage of the statistical method introduced in Lavalle et al. (2007) and
cross-check the results with Monte Carlo computations. By spanning some extreme
configurations of sub-halo and propagation properties, we find that the average
contribution of the clumps is negligible compared to that of the smooth dark
matter component. Sub-halos do not lead to enhancement of the signals, unless
they are taken with some extreme (unexpected) properties. This result is
independent of the nature of the self-annihilating dark matter candidate
considered, and provides precise estimates of the theoretical and the
statistical uncertainties of the antimatter flux from dark matter
substructures. Spectral distortions can still be expected in antimatter flux
measurements, but scenarios invoking large and even mild clumpiness boost
factors are strongly disfavoured by our analysis.


title: High redshift FRII radio sources: large-scale X-ray environment

abstract:
  We investigate the properties of the environment around 20 powerful radio
galaxies and quasars at redshifts between 0.45 and 1. Using XMM-Newton and
Chandra observations we probe the spatial distribution and the temperature of
the cluster gas. We find that more than 60 per cent of powerful radio sources
in the redshift range of our sample lie in a cluster of X-ray luminosity
greater than 10^44 erg/s, and all but one of the narrow-line radio galaxies,
for which the emission from the nucleus is obscured by a torus, lie in a
cluster environment. Within the statistical uncertainties we find no
significant difference in the properties of the environment as a function of
the orientation to the line of sight of the radio jet. This is in agreement
with unification schemes. Our results have important implications for cluster
surveys, as clusters around powerful radio sources tend to be excluded from
X-ray and Sunyaev-Zeldovich surveys of galaxy clusters, and thus can introduce
an important bias in the cluster luminosity function. Most of the radio sources
are found close to pressure balance with the environment in which they lie, but
the two low-excitation radio galaxies of the sample are observed to be
under-pressured. This may be the first observational indication for the
presence of non-radiative particles in the lobes of some powerful radio
galaxies. We find that the clusters around radio sources in the redshift range
of our sample have a steeper entropy-temperature relation than local clusters,
and the slope is in agreement with the predictions of self-similar
gravitational heating models for cluster gas infall. This suggests that
selection by AGN finds systems less affected by AGN feedback than the local
average.(Abridged)


title: Detecting Neutrino Magnetic Moments with Conducting Loops

abstract:
  It is well established that neutrinos have mass, yet it is very difficult to
measure those masses directly. Within the standard model of particle physics,
neutrinos will have an intrinsic magnetic moment proportional to their mass. We
examine the possibility of detecting the magnetic moment using a conducting
loop. According to Faraday's Law of Induction, a magnetic dipole passing
through a conducting loop induces an electromotive force, or EMF, in the loop.
We compute this EMF for neutrinos in several cases, based on a fully covariant
formulation of the problem. We discuss prospects for a real experiment, as well
as the possibility to test the relativistic formulation of intrinsic magnetic
moments.


title: \Lambda_{c} enhancement from strongly coupled quark-gluon plasma

abstract:
  We propose the enhancement of $\Lambda_{c}$ as a novel QGP signal in heavy
ion collisions at RHIC and LHC. Assuming a stable bound diquark state in the
strongly coupled QGP near the critical temperature, we argue that the direct
two-body collision between a $c$ quark and a $[ud]$ diquark would lead to an
enhanced $\Lambda_{c}$ production in comparison with the normal three-body
collision among independent $c$, $u$ and $d$ quarks. In the coalescence model,
we find that the $\Lambda_{c}/D$ yield ratio is enhanced substantially due to
the diquark correlation.


title: Dynamical Casimir Effect and the Black Body Spectrum

abstract:
  Creation of scalar massless particles in two-dimensional Minkowski
space-time--as predicted by the dynamical Casimir effect--is studied for the
case of a semitransparent mirror initially at rest, then accelerating for some
finite time, along a specified trajectory, and finally moving with constant
velocity. When the reflection and transmission coefficients are those in the
model proposed by Barton, Calogeracos, and Nicolaevici
[$r(w)=-i\alpha/(\w+i\alpha)$ and $s(w)=\w/(\w+i\alpha)$, with $\alpha\geq 0$],
the Bogoliubov coefficients on the back side of the mirror can be computed
exactly. This allows us to prove that, when $\alpha$ is very large (case of an
ideal, perfectly reflecting mirror) a thermal emission of scalar massless
particles obeying Bose-Einstein statistics is radiated from the mirror (a black
body radiation), in accordance with previous results in the literature.
However, when $\alpha$ is finite (semitransparent mirror, a physically
realistic situation) the striking result is obtained that the thermal emission
of scalar massless particles obeys Fermi-Dirac statistics. Possible
consequences of this result are envisaged.


title: Fast Selection of Spectral Variables with B-Spline Compression

abstract:
  The large number of spectral variables in most data sets encountered in
spectral chemometrics often renders the prediction of a dependent variable
uneasy. The number of variables hopefully can be reduced, by using either
projection techniques or selection methods; the latter allow for the
interpretation of the selected variables. Since the optimal approach of testing
all possible subsets of variables with the prediction model is intractable, an
incremental selection approach using a nonparametric statistics is a good
option, as it avoids the computationally intensive use of the model itself. It
has two drawbacks however: the number of groups of variables to test is still
huge, and colinearities can make the results unstable. To overcome these
limitations, this paper presents a method to select groups of spectral
variables. It consists in a forward-backward procedure applied to the
coefficients of a B-Spline representation of the spectra. The criterion used in
the forward-backward procedure is the mutual information, allowing to find
nonlinear dependencies between variables, on the contrary of the generally used
correlation. The spline representation is used to get interpretability of the
results, as groups of consecutive spectral variables will be selected. The
experiments conducted on NIR spectra from fescue grass and diesel fuels show
that the method provides clearly identified groups of selected variables,
making interpretation easy, while keeping a low computational load. The
prediction performances obtained using the selected coefficients are higher
than those obtained by the same method applied directly to the original
variables and similar to those obtained using traditional models, although
using significantly less spectral variables.


title:
Resampling methods for parameter-free and robust feature selection with
  mutual information

abstract:
  Combining the mutual information criterion with a forward feature selection
strategy offers a good trade-off between optimality of the selected feature
subset and computation time. However, it requires to set the parameter(s) of
the mutual information estimator and to determine when to halt the forward
procedure. These two choices are difficult to make because, as the
dimensionality of the subset increases, the estimation of the mutual
information becomes less and less reliable. This paper proposes to use
resampling methods, a K-fold cross-validation and the permutation test, to
address both issues. The resampling methods bring information about the
variance of the estimator, information which can then be used to automatically
set the parameter and to calculate a threshold to stop the forward procedure.
The procedure is illustrated on a synthetic dataset as well as on real-world
examples.


title: Representation of Functional Data in Neural Networks

abstract:
  Functional Data Analysis (FDA) is an extension of traditional data analysis
to functional data, for example spectra, temporal series, spatio-temporal
images, gesture recognition data, etc. Functional data are rarely known in
practice; usually a regular or irregular sampling is known. For this reason,
some processing is needed in order to benefit from the smooth character of
functional data in the analysis methods. This paper shows how to extend the
Radial-Basis Function Networks (RBFN) and Multi-Layer Perceptron (MLP) models
to functional data inputs, in particular when the latter are known through
lists of input-output pairs. Various possibilities for functional processing
are discussed, including the projection on smooth bases, Functional Principal
Component Analysis, functional centering and reduction, and the use of
differential operators. It is shown how to incorporate these functional
processing into the RBFN and MLP models. The functional approach is illustrated
on a benchmark of spectrometric data analysis.


title:
Functional Multi-Layer Perceptron: a Nonlinear Tool for Functional Data
  Analysis

abstract:
  In this paper, we study a natural extension of Multi-Layer Perceptrons (MLP)
to functional inputs. We show that fundamental results for classical MLP can be
extended to functional MLP. We obtain universal approximation results that show
the expressive power of functional MLP is comparable to that of numerical MLP.
We obtain consistency results which imply that the estimation of optimal
parameters for functional MLP is statistically well defined. We finally show on
simulated and real world data that the proposed model performs in a very
satisfactory way.


title:
Broad Line Emission in Low-Metallicity Blue Compact Dwarf Galaxies:
  Evidence for Stellar Wind, Supernova and Possible AGN Activity

abstract:
  We present spectra of a large sample of low-metallicity blue compact dwarf
galaxies which exhibit broad components in their strong emission lines, mainly
in Hbeta, [O III]4959, 5007 and Halpha. Twenty-three spectra have been obtained
with the MMT, 14 of which show broad emission. The remaining 21 spectra with
broad emission have been selected from the Data Release 5 of the Sloan Digital
Sky Survey. The most plausible origin of broad line emission is the evolution
of massive stars and their interaction with the circumstellar and interstellar
medium. The broad emission with the lowest H$\alpha$ luminosities (10^36 -
10^39 erg/s) is likely produced in circumstellar envelopes around hot Ofp/WN9
and/or LBV stars. The broad emission with the highest Halpha luminosities
(10^40 - 10^42 erg/s) probably arises from type IIp or type IIn supernovae
(SNe). It can also come from active galactic nuclei (AGN) containing
intermediate-mass black holes, although we find no strong evidence for hard
non-thermal radiation in our sample galaxies. The oxygen abundance in the host
galaxies with SN candidates is low and varies in the range 12 + log O/H = 7.36
- 8.31. However, type IIn SN / AGN candidates are found only in galaxies with
12 + log O/H < 7.99. Spectroscopic monitoring of these type IIn SN / AGN
candidates over a time scale of several years is necessary to distinguish
between the two possibilities.


title: Radio Source Heating in the ICM: The Example of Cygnus A

abstract:
  One of the most promising solutions for the cooling flow problem involves
energy injection from the central AGN. However it is still not clear how
collimated jets can heat the ICM at large scale, and very little is known
concerning the effect of radio lobe expansion as they enter into pressure
equilibrium with the surrounding cluster gas. Cygnus A is one of the best
examples of a nearby powerful radio galaxy for which the synchrotron emitting
plasma and thermal emitting intra-cluster medium can be mapped in fine detail,
and previous observations have inferred possible shock structure at the
location of the cocoon. We use new XMM-Newton observations of Cygnus A, in
combination with deep Chandra observations, to measure the temperature of the
intra-cluster medium around the expanding radio cavities. We investigate how
inflation of the cavities may relate to shock heating of the intra-cluster gas,
and whether such a mechanism is sufficient to provide enough energy to offset
cooling to the extent observed.


title:
Stable First-order Particle-frame Relativistic Hydrodynamics for
  Dissipative Systems

abstract:
  We propose a stable first-order relativistic dissipative hydrodynamic
equation in the particle frame (Eckart frame) for the first time. The equation
to be proposed was in fact previously derived by the authors and a collaborator
from the relativistic Boltzmann equation. We demonstrate that the equilibrium
state is stable with respect to the time evolution described by our
hydrodynamic equation in the particle frame. Our equation may be a proper
starting point for constructing second-order causal relativistic hydrodynamics,
to replace Eckart's particle-flow theory.


title: A convenient category of locally preordered spaces

abstract:
  As a practical foundation for a homotopy theory of abstract spacetime, we
extend a category of certain compact partially ordered spaces to a convenient
category of locally preordered spaces. In particular, we show that our new
category is Cartesian closed and that the forgetful functor to the category of
compactly generated spaces creates all limits and colimits.


title:
A light non-standard Higgs boson: to be or not to be at a (Super) B
  factory?

abstract:
  A light non-standard Higgs boson decaying mainly into $\tau^+\tau^-$ has not
been yet ruled out by LEP searches in several scenarios. We verify that, in the
context of the Next-to-Minimal-Supersymmetric Standard Model, a low-mass CP-odd
(mostly but not completely singlet-like) Higgs boson can couple strongly enough
to down-type fermions to be detected in radiative $\Upsilon$ decays into
tauonic pairs at a high-luminosity B factory. Possible spectroscopic effects of
a mixing with $\eta_b$ resonances are also analyzed


title:
On the Correlations, Selberg Integral and Symmetry of Sieve Functions in
  Short Intervals

abstract:
  We study the arithmetic (real) function f=g*1, with g "essentially bounded"
and supported over the integers of [1,Q]. In particular, we obtain non-trivial
bounds, through f "correlations", for the "Selberg integral" and the "symmetry
integral" of f in almost all short intervals [x-h,x+h], N<x<2N, beyond the
"classical" level, up to level of distribution, say, lambda=log Q/log N < 2/3
(for enough large h). This time we don't apply Large Sieve inequality, as in
our paper [C-S]. Precisely, our method is completely elementary.


title:
Spin and orbital angular momentum in gauge theories (I): QED and
  determination of the angular momentum density

abstract:
  This two-paper series addresses and fixes the long-standing gauge invariance
problem of angular momentum in gauge theories. This QED part reveals: 1) The
spin and orbital angular momenta of electrons and photons can all be
consistently defined gauge invariantly. 2) These gauge-invariant quantities can
be conveniently computed via the canonical, gauge-dependent operators (e.g,
$\psi ^\dagger \vec x \times\frac 1i \vec \nabla \psi$) in the Coulomb gauge,
which is in fact what people (unconsciously) do in atomic physics. 3) The
renowned formula $\vec x\times(\vec E\times\vec B)$ is a wrong density for the
electromagnetic angular momentum. The angular distribution of angular-momentum
flow in polarized atomic radiation is properly described not by this formula,
but by the gauge invariant quantities defined here. The QCD paper
[arXiv:0907.1284] will give a non-trivial generalization to non-Abelian gauge
theories, and discuss the connection to nucleon spin structure.


title:
A Support Theorem For The Radiation Fields On Asymptotically Euclidean
  Manifolds

abstract:
  We prove a support theorem for the radiation fields on asymptotically
Euclidean manifolds with metrics which are warped products near infinity. It
generalizes to this setting the well known support theorem for the Radon
transform on n-dimensional Euclidean space.


title: A further look into combinatorial orthogonality

abstract:
  Strongly quadrangular matrices have been introduced in the study of the
combinatorial properties of unitary matrices. It is known that if a (0,
1)-matrix supports a unitary then it is strongly quadrangular. However, the
converse is not necessarily true. In this paper, we fully classify strongly
quadrangular matrices up to degree 5. We prove that the smallest strongly
quadrangular matrices which do not support unitaries have exactly degree 5.
Further, we isolate two submatrices not allowing a (0, 1)-matrix to support
unitaries.


title: Massive vectors from projective-invariance breaking

abstract:
  A general affine connection has enough degrees of freedom to describe the
classical gravitational and electromagnetic fields in the metric-affine
formulation of gravity. The gravitational field is represented in the
Lagrangian by the symmetric part of the Ricci tensor and the classical
electromagnetic field can be represented by the tensor of homothetic curvature.
The simplest metric-affine Lagrangian that depends on the tensor of homothetic
curvature generates the Einstein-Maxwell equations for a massless vector.
Metric-affine Lagrangians with matter fields depending on the connection are
subject to an unphysical constraint because the symmetrized Ricci tensor is
projectively invariant while matter fields are not. We show that the appearance
of the tensor of homothetic curvature, which is not projectively invariant, in
the Lagrangian replaces this constraint with the Maxwell equations and restores
projective invariance of the total action. We also examine several constraints
on the torsion tensor to show that algebraic constraints on the torsion that
break projective invariance of the connection and impose projective invariance
on the tensor of homothetic curvature replace the massless vector with a
massive vector. We conclude that the metric-affine formulation of gravity
allows for a mechanism that generates masses of vectors, as it happens for
electroweak gauge bosons via spontaneous symmetry breaking.


title: Two Scenarios of the Quantum Critical Point

abstract:
  Two different scenarios of the quantum critical point (QCP), a
zero-temperature instability of the Landau state, related to the divergence of
the effective mass, are investigated. Flaws of the standard scenario of the
QCP, where this divergence is attributed to the occurrence of some second-order
phase transition, are demonstrated. Salient features of a different {\it
topological} scenario of the QCP, associated with the emergence of bifurcation
points in equation $\epsilon(p)=\mu$ that ordinarily determines the Fermi
momentum, are analyzed. The topological scenario of the QCP is applied to
three-dimensional (3D) Fermi liquids with an attractive current-current
interaction.


title: VERITAS: Status and Latest Results

abstract:
  VERITAS is an atmospheric Cherenkov telescope array designed to study
astrophysi cal sources of very-high-energy gamma radiation. Located in southern
Arizona, USA, the array consists of four 12m-diameter imaging Cherenkov
telescopes. All four telescopes have been deployed at the basecamp of the
Whipple Observatory and began full operation in early 2007. This paper
describes the operational status of VERITAS, outlines the initial performance
parameters of the instrument, and presents the latest results that have been
obtained.


title: Nonlinear paramagnetic magnetization in the mixed state of CeCoIn_5

abstract:
  Torque and magnetization measurements in magnetic fields $H$ up to 14 T were
performed on CeCoIn$_5$ single crystals. The amplitude of the paramagnetic
torque shows an $H^{2.3}$ dependence in the mixed state and an $H^{2}$
dependence in the normal state. In addition, the mixed-state magnetizations for
both $H\parallel c$ and $H\parallel ab$ axes show anomalous behavior after the
subtraction of the corresponding paramagnetic contributions as linear
extrapolations of the normal-state magnetization. These experimental results
point towards a nonlinear paramagnetic magnetization in the mixed state of
CeCoIn$_5$, which is a result of the fact that both orbital and Pauli limiting
effects dominate in the mixed state.


title:
A simple construction of fermion measure term in U(1) chiral lattice
  gauge theories with exact gauge invariance

abstract:
  In the gauge invariant formulation of U(1) chiral lattice gauge theories
based on the Ginsparg-Wilson relation, the gauge field dependence of the
fermion measure is determined through the so-called measure term. We derive a
closed formula of the measure term on the finite volume lattice. The Wilson
line degrees of freedom (torons) of the link field are treated separately to
take care of the global integrability. The local counter term is explicitly
constructed with the local current associated with the cohomologically trivial
part of the gauge anomaly in a finite volume. The resulted formula is very
close to the known expression of the measure term in the infinite volume with a
single parameter integration, and would be useful in practical implementations.


title:
Observations of the high-frequency-peaked BL Lac object 1ES 1218+304
  with VERITAS

abstract:
  The VERITAS collaboration has observed the high-frequency-peaked BL Lac
object 1ES 1218+304 using an array of several imaging Cherenkov telescopes
located at the Fred Lawrence Whipple Observatory in Southern Arizona. A
gamma-ray signal was detected with high significance for the observations taken
during several months in the 2006-2007 observing season. Here we present the
detection of 1ES 1218+304 in very-high-energy gamma rays.


title:
A construction of the Glashow-Weinberg-Salam model on the lattice with
  exact gauge invariance

abstract:
  We present a gauge-invariant and non-perturbative construction of the
Glashow-Weinberg-Salam model on the lattice, based on the lattice Dirac
operator satisfying the Ginsparg-Wilson relation. Our construction covers all
SU(2) topological sectors with vanishing U(1) magnetic flux and would be usable
for a description of the baryon number non-conservation. In infinite volume, it
provides a gauge-invariant regularization of the electroweak theory to all
orders of perturbation theory. First we formulate the reconstruction theorem
which asserts that if there exists a set of local currents satisfying cetain
properties, it is possible to reconstruct the fermion measure which depends
smoothly on the gauge fields and fulfills the fundamental requirements such as
locality, gauge-invariance and lattice symmetries. Then we give a closed
formula of the local currents required for the reconstruction theorem.


title: Observations of Mrk 421 and Mrk 501 in Spring 2006 with VERITAS

abstract:
  VERITAS, the Very Energetic Radiation Telescope Imaging Array System, is an
array of four imaging Atmospheric Cherenkov telescopes in southern Arizona. It
is sensitive to gamma rays at energies above 100 GeV. Here, we discuss the
results of observations of two well known VHE blazars, Markarian 421 and
Markarian 501, during Spring 2006 which were made with the first two telescopes
during the comissioning phase of VERITAS. During most of this time Mrk 421 was
in an unusually active state while Mrk 501 was in a much lower flux state. As
such, these observations provided an opportunity to test the sensitivity of the
instrument to strong and weak sources. We discuss implications of these
observations on our understanding of these objects.


title: Einstein's equations and the embedding of 3-dimensional CR manifolds

abstract:
  We prove several theorems concerning the connection between the local CR
embeddability of 3-dimensional CR manifolds, and the existence of algebraically
special Maxwell and gravitational fields. We reduce the Einstein equations for
spacetimes associated with such fields to a system of CR invariant equations on
a 3-dimensional CR manifold defined by the fields. Using the reduced Einstein
equations we construct two independent CR functions for the corresponding CR
manifold. We also point out that the Einstein equations, imposed on spacetimes
associated with a 3-dimensional CR manifold, imply that the spacetime metric,
after an appropriate rescaling, becomes well defined on a circle bundle over
the CR manifold. The circle bundle itself emerges as a consequence of
Einstein's equations.


title: Observation of LS I +61 303 with VERITAS

abstract:
  The high mass X-ray binary LS I +61 303 has been observed over several months
in 2006 and 2007 with the VERITAS array of imaging air-Cherenkov telescopes. A
signal of high energy gamma rays with energies above 350 GeV is detected in
several orbital cycles of the binary system. The detected flux of gamma rays is
strongly variable with the orbital period of 26.5 days, while the maximum flux
(corresponding to about 10% of the flux of the Crab Nebula)is always found at
approximately apastron, suggesting a strong dependence of particle acceleration
and/or propagation on the relative position of the two objects in the system.


title: Econophysics, Statistical Mechanics Approach to

abstract:
  This is a review article for Encyclopedia of Complexity and System Science,
to be published by Springer http://refworks.springer.com/complexity/. The paper
reviews statistical models for money, wealth, and income distributions
developed in the econophysics literature since late 1990s.

categories: q-fin.ST cond-mat.stat-mech physics.data-an physics.soc-ph stat.AP


title: Observation of M87 with VERITAS

abstract:
  The giant radio galaxy M87 is the only extragalactic non-blazar object which
has been detected as a source of very high energy gamma-rays. It represents a
unique opportunity to study the phenomena of gamma-ray emission from a nearby
AGN. In this paper we report preliminary results from the observations of M87
taken with the imaging atmospheric Cherenkov telescope array VERITAS in
February, March and April 2007. An excess of photons above an energy threshold
of 250 GeV is measured with a sta tistical significance of more than five
standard deviations.


title: Connecting SLE and minisuperspace Liouville gravity

abstract:
  We show that Fokker-Planck equation for chordal SLE process under a simple
rescaling of the probability density can be traced to the minisuperspace
Wheeler-de Witt equation for boundary operator in 2d Liouville gravity.
Insertion of an operator, calculating SLE critical exponent, corresponds to
adding matter contribution to WdW equation. This observation may be useful for
understanding of why SLE critical exponents are given by KPZ gravitational
scaling dimensions. Possible applications of the obtained relation are
discussed.