title:
Dynamical quark recombination in ultrarelativistic heavy-ion collisions
  and the proton to pion ratio

abstract:
  We study quark thermal recombination as a function of energy density during
the evolution of a heavy-ion collision in a numerical model that reproduces
aspects of QCD phenomenology. We show that starting with a set of free quarks
(or quarks and antiquarks) the probability to form colorless clusters of three
quarks differs from that to form colorless clusters of quark-antiquark and that
the former has a sharp jump at a critical energy density whereas the latter
transits smoothly from the low to the high energy density domains. We interpret
this as a quantitative difference in the production of baryons and mesons with
energy density. We use this approach to compute the proton and pion spectra in
a Bjorken scenario that incorporates the evolution of these probabilities with
energy density, and therefore with proper time. From the spectra, we compute
the proton to pion ratio and compare to data at the highest RHIC energies. We
show that for a standard choice of parameters, this ratio reaches one, though
the maximum is very sensitive to the initial evolution proper time.


title: Scattering for the non-radial 3D cubic nonlinear Schroedinger equation

abstract:
  Scattering of radial $H^1$ solutions to the 3D focusing cubic nonlinear
Schr\"odinger equation below a mass-energy threshold $M[u]E[u] < M[Q]E[Q]$ and
satisfying an initial mass-gradient bound $\|u_0\|_{L^2} \|\nabla u_0 \|_{L^2}
< \|Q\|_{L^2} \|\nabla Q\|_{L^2}$, where $Q$ is the ground state, was
established in Holmer-Roudenko (2007). In this note, we extend the result in
Holmer-Roudenko (2007) to non-radial $H^1$ data. For this, we prove a
non-radial profile decomposition involving a spatial translation parameter.
Then, in the spirit of Kenig-Merle (2006), we control via momentum conservation
the rate of divergence of the spatial translation parameter and by a convexity
argument based on a local virial identity deduce scattering. An application to
the defocusing case is also mentioned.


title: The Interaction of Stellar Objects within a Common Envelope

abstract:
  We use high-resolution, three-dimensional hydrodynamic simulations to study
the hydrodynamic and gravitational interaction between stellar companions
embedded within a differentially rotating common envelope. Specifically, we
evaluate the contributions of the nonaxisymmetric gravitational tides and ram
pressure forces to the drag force and, hence, to the dissipation rate and the
mass accumulated onto the stellar companion. We find that the gravitational
drag dominates the hydrodynamic drag during the inspiral phase, leading to the
result that a simple prescription based on a gravitational capture radius
formalism significantly underestimates the dissipation rate and overestimates
the inspiral decay timescale. Although the rate of mass accretion fluctuates
significantly, we observe a secular trend leading to an effective rate of mass
accretion which is significantly less than the rate based on a gravitational
capture radius. The implications of these results are discussed within the
context of accretion of compact objects in the common-envelope phase.


title: 2-pile Nim with a Restricted Number of Move-size Imitations

abstract:
  We study a variation of the combinatorial game of 2-pile Nim. Move as in
2-pile Nim but with the following constraint:
  Suppose the previous player has just removed say $x>0$ tokens from the
shorter pile (either pile in case they have the same height). If the next
player now removes $x$ tokens from the larger pile, then he imitates his
opponent. For a predetermined natural number $p$, by the rules of the game,
neither player is allowed to imitate his opponent on more than $p-1$
consecutive moves.
  We prove that the strategy of this game resembles closely that of a variant
of Wythoff Nim--a variant with a blocking manoeuvre on $p-1$ diagonal
positions. In fact, we show a slightly more general result in which we have
relaxed the notion of what an imitation is.


title: Dynamics in Thompson's Group F

abstract:
  We describe an explicit relationship between strand diagrams and
piecewise-linear functions for elements of Thompson's group F. Using this
correspondence, we investigate the dynamics of elements of F, and we show that
conjugacy of one-bump functions can be described by a Mather-type invariant.


title: Neutrino Emission From Inhomogeneous Pion Condensed Quark Matter

abstract:
  It is believed that quark matter can exist in neutron star interior if the
baryon density is high enough. When there is a large isospin density, quark
matter could be in a pion condensed phase. We compute neutrino emission from
direct Urca processes in such a phase, particularly in the inhomogeneous
Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states. The neutrino emissivity and
specific heat are obtained, from which the cooling rate is estimated.


title:
Spectral beam combining of Yb-doped fiber lasers using wavelength
  dependent polarization rotators and polarization beam combiners

abstract:
  We propose a robust spectral beam combining scheme using wavelength dependent
polarisation rotators and polarization beam combiners. We successfully
demonstrated the concept for two Yb-doped fiber lasers at 1064nm and 1092nm up
to a total input power of 90W. The results reveal a very good combining
efficiency and the potential for scaling to high power operations in this
method of beam combining.


title: The evolution of the peculiar Type Ia supernova SN 2005hk over 400 days

abstract:
  $UBVRI$ photometry and medium resolution optical spectroscopy of peculiar
Type Ia supernova SN 2005hk are presented and analysed, covering the
pre-maximum phase to around 400 days after explosion. The supernova is found to
be underluminous compared to "normal" Type Ia supernovae. The photometric and
spectroscopic evolution of SN 2005hk is remarkably similar to the peculiar Type
Ia event SN 2002cx. The expansion velocity of the supernova ejecta is found to
be lower than normal Type Ia events. The spectra obtained $\gsim 200$ days
since explosion do not show the presence of forbidden [\ion{Fe}{ii}],
[\ion{Fe}{iii}] and [\ion{Co}{iii}] lines, but are dominated by narrow,
permitted \ion{Fe}{ii}, NIR \ion{Ca}{ii} and \ion{Na}{i} lines with P-Cygni
profiles. Thermonuclear explosion model with Chandrasekhar mass ejecta and a
kinetic energy smaller ($\KE = 0.3 \times 10^{51} {\rm ergs}$) than that of
canonical Type Ia supernovae is found to well explain the observed bolometric
light curve. The mass of \Nifs synthesized in this explosion is $0.18 \Msun$.
The early spectra are successfully modeled with this less energetic model with
some modifications of the abundance distribution. The late spectrum is
explained as a combination of a photospheric component and a nebular component.


title: A Rigidity Theorem for Affine K\"ahler-Ricci Flat Graph

abstract:
  It is shown that any smooth strictly convex global solution of
$$\det(\frac{\partial^{2}u}{\partial \xi_{i}\partial \xi_{j}}) = \exp
\left\{-\sum_{i=1}^n d_i \frac{\partial u}{\partial \xi_{i}} - d_0\right\},$$
where $d_0$, $d_1$,...,$d_n$ are constants, must be a quadratic polynomial.
This extends a well-known theorem of J\"{o}rgens-Calabi-Pogorelov.


title:
Nonparametric estimation of correlation functions in longitudinal and
  spatial data, with application to colon carcinogenesis experiments

abstract:
  In longitudinal and spatial studies, observations often demonstrate strong
correlations that are stationary in time or distance lags, and the times or
locations of these data being sampled may not be homogeneous. We propose a
nonparametric estimator of the correlation function in such data, using kernel
methods. We develop a pointwise asymptotic normal distribution for the proposed
estimator, when the number of subjects is fixed and the number of vectors or
functions within each subject goes to infinity. Based on the asymptotic theory,
we propose a weighted block bootstrapping method for making inferences about
the correlation function, where the weights account for the inhomogeneity of
the distribution of the times or locations. The method is applied to a data set
from a colon carcinogenesis study, in which colonic crypts were sampled from a
piece of colon segment from each of the 12 rats in the experiment and the
expression level of p27, an important cell cycle protein, was then measured for
each cell within the sampled crypts. A simulation study is also provided to
illustrate the numerical performance of the proposed method.


title:
Radiative Corrections to High Energy Lepton Bremsstrahlung on Heavy
  Nuclei

abstract:
  One-loop radiative corrections to the leptonic tensor in high energy
bremsstrahlung on heavy nuclei are calculated. Virtual and real photon
radiation is taken into account. Double bremsstrahlung is simulated by means of
Monte Carlo. Numerical results are presented for the case of muon
bremsstrahlung in conditions of the COMPASS experiment at CERN.


title: A dynamic look-ahead Monte Carlo algorithm for pricing Bermudan options

abstract:
  Under the assumption of no-arbitrage, the pricing of American and Bermudan
options can be casted into optimal stopping problems. We propose a new adaptive
simulation based algorithm for the numerical solution of optimal stopping
problems in discrete time. Our approach is to recursively compute the so-called
continuation values. They are defined as regression functions of the cash flow,
which would occur over a series of subsequent time periods, if the approximated
optimal exercise strategy is applied. We use nonparametric least squares
regression estimates to approximate the continuation values from a set of
sample paths which we simulate from the underlying stochastic process. The
parameters of the regression estimates and the regression problems are chosen
in a data-dependent manner. We present results concerning the consistency and
rate of convergence of the new algorithm. Finally, we illustrate its
performance by pricing high-dimensional Bermudan basket options with
strangle-spread payoff based on the average of the underlying assets.


title:
The Euler Characteristic Formula for Logarithmic Minimal Degenerations
  of Surfaces with Kodaira Dimension Zero and its application to Calabi-Yau
  Threefolds with a pencil

abstract:
  In this paper, the Euler characteristic formula for projective logarithmic
minimal degenerations of surfaces with Kodaira dimension zero over a
1-dimensional complex disk is proved under a reasonable assumption and as its
application, the singularity of logarithmic minimal degenerations are
determined in the abelian or hyperelliptic case. By globalizing this local
analysis of singular fibres via generalized canonical bundle formulae due to
Fujino-Mori, we bound the number of singular fibres of abelian fibred
Calabi-Yau threefolds from above,which was previously done by Oguiso in the
potentially good reduction case.


title: On the Complexity of Spill Everywhere under SSA Form

abstract:
  Compilation for embedded processors can be either aggressive (time consuming
cross-compilation) or just in time (embedded and usually dynamic). The
heuristics used in dynamic compilation are highly constrained by limited
resources, time and memory in particular. Recent results on the SSA form open
promising directions for the design of new register allocation heuristics for
embedded systems and especially for embedded compilation. In particular,
heuristics based on tree scan with two separated phases -- one for spilling,
then one for coloring/coalescing -- seem good candidates for designing
memory-friendly, fast, and competitive register allocators. Still, also because
of the side effect on power consumption, the minimization of loads and stores
overhead (spilling problem) is an important issue. This paper provides an
exhaustive study of the complexity of the ``spill everywhere'' problem in the
context of the SSA form. Unfortunately, conversely to our initial hopes, many
of the questions we raised lead to NP-completeness results. We identify some
polynomial cases but that are impractical in JIT context. Nevertheless, they
can give hints to simplify formulations for the design of aggressive
allocators.


title: Stabilizing a purely dipolar quantum gas against collapse

abstract:
  We report on the experimental observation of the dipolar collapse of a
quantum gas which sets in when we reduce the contact interaction below some
critical value using a Feshbach resonance. Due to the anisotropy of the
dipole-dipole interaction, the stability of a dipolar Bose-Einstein condensate
depends not only on the strength of the contact interaction, but also on the
trapping geometry. We investigate the stability diagram and find good agreement
with a universal stability threshold arising from a simple theoretical model.
Using a pancake-shaped trap with the dipoles oriented along the short axis of
the trap, we are able to tune the scattering length to zero, stabilizing a
purely dipolar quantum gas.


title:
Heavy-fermion metals with hybridization nodes: Unconventional Fermi
  liquids and competing phases

abstract:
  Microscopic models for heavy-fermion materials often assume a local, i.e.,
momentum-independent, hybridization between the conduction band and the
local-moment f electrons. Motivated by recent experiments, we consider
situations where this neglect of momentum dependence is inappropriate, namely
when the hybridization function has nodes in momentum space. We explore the
thermodynamic and optical properties of the highly anisotropic heavy Fermi
liquid, resulting from Kondo screening in a higher angular-momentum channel.
The dichotomy in momentum space has interesting consequences: While e.g. the
low-temperature specific heat is dominated by heavy quasiparticles, the
electrical conductivity at intermediate temperatures is carried by unhybridized
light electrons. We then discuss aspects of the competition between Kondo
effect and ordering phenomena induced by inter-moment exchange: We propose that
the strong momentum-space anisotropy plays a vital role in selecting competing
phases. Explicit results are obtained for the interplay of unconventional
hybridization with unconventional, magnetically mediated, superconductivity,
utilizing variants of large-N mean-field theory. We make connections to recent
experiments on CeCoIn5 and other heavy-fermion materials.


title:
The k-generalized distribution: A new descriptive model for the size
  distribution of incomes

abstract:
  This paper proposes the k-generalized distribution as a model for describing
the distribution and dispersion of income within a population. Formulas for the
shape, moments and standard tools for inequality measurement - such as the
Lorenz curve and the Gini coefficient - are given. A method for parameter
estimation is also discussed. The model is shown to fit extremely well the data
on personal income distribution in Australia and the United States.


title: Thermodynamic time asymmetry in nonequilibrium fluctuations

abstract:
  We here present the complete analysis of experiments on driven Brownian
motion and electric noise in a $RC$ circuit, showing that thermodynamic entropy
production can be related to the breaking of time-reversal symmetry in the
statistical description of these nonequilibrium systems. The symmetry breaking
can be expressed in terms of dynamical entropies per unit time, one for the
forward process and the other for the time-reversed process. These entropies
per unit time characterize dynamical randomness, i.e., temporal disorder, in
time series of the nonequilibrium fluctuations. Their difference gives the
well-known thermodynamic entropy production, which thus finds its origin in the
time asymmetry of dynamical randomness, alias temporal disorder, in systems
driven out of equilibrium.


title:
Asymptotic approximation of nonparametric regression experiments with
  unknown variances

abstract:
  Asymptotic equivalence results for nonparametric regression experiments have
always assumed that the variances of the observations are known. In practice,
however the variance of each observation is generally considered to be an
unknown nuisance parameter. We establish an asymptotic approximation to the
nonparametric regression experiment when the value of the variance is an
additional parameter to be estimated or tested. This asymptotically equivalent
experiment has two components: the first contains all the information about the
variance and the second has all the information about the mean. The result can
be extended to regression problems where the variance varies slowly from
observation to observation.


title:
Hydrodynamic stability and mode coupling in Keplerian flows: local
  strato-rotational analysis

abstract:
  Aims. Qualitative analysis of key (but yet unappreciated) linear phenomena in
stratified hydrodynamic Keplerian flows: (i) the occurrence of a vortex mode,
as a consequence of strato-rotational balance, with its transient dynamics;
(ii) the generation of spiral-density waves (also called inertia-gravity or
$g\Omega$ waves) by the vortex mode through linear mode coupling in shear
flows. Methods. Non-modal analysis of linearized Boussinesq equations written
in the shearing sheet approximation of accretion disk flows. Results. It is
shown that the combined action of rotation and stratification introduces a new
degree of freedom -- vortex mode perturbation -- which is linearly coupled with
the spiral-density waves. These two modes are jointly able to extract energy
from the background flow and they govern the disk dynamics in the small-scale
range. The transient behavior of these modes is determined by the non-normality
of the Keplerian shear flow. Tightly leading vortex mode perturbations undergo
substantial transient growth, then, becoming trailing, inevitably generate
trailing spiral-density waves by linear mode coupling. This course of events --
transient growth plus coupling -- is particularly pronounced for perturbation
harmonics with comparable azimuthal and vertical scales and it renders the
energy dynamics similar to the 3D unbounded plane Couette flow case.
Conclusions. Our investigation strongly suggests that the so-called bypass
concept of turbulence, which has been recently developed by the hydrodynamic
community for spectrally stable shear flows, can also be applied to Keplerian
disks. This conjecture may be confirmed by appropriate numerical simulations
that take in account the vertical stratification and consequent mode coupling
in the high Reynolds number regime.


title:
CMB Temperature Polarization Correlation and Primordial Gravitational
  Waves

abstract:
  We examine the use of the CMB's TE cross correlation power spectrum as a
complementary test to detect primordial gravitational waves (PGWs). The first
method used is based on the determination of the lowest multipole, $\ell_0$,
where the TE power spectrum, $C_{\ell}^{TE}$, first changes sign. The second
method uses Wiener filtering on the CMB TE data to remove the density
perturbations contribution to the TE power spectrum. In principle this leaves
only the contribution of PGWs. We examine two toy experiments (one ideal and
another more realistic) to see their ability to constrain PGWs using the TE
power spectrum alone. We found that an ideal experiment, one limited only by
cosmic variance, can detect PGWs with a ratio of tensor to scalar metric
perturbation power spectra $r=0.3$ at 99.9% confidence level using only the TE
correlation. This value is comparable with current constraints obtained by WMAP
based on the $2\sigma$ upper limits to the B-mode amplitude. We demonstrate
that to measure PGWs by their contribution to the TE cross correlation power
spectrum in a realistic ground based experiment when real instrumental noise is
taken into account, the tensor-to-scalar ratio, $r$, should be approximately
three times larger.


title: Linearization of holomorphic germs with quasi-Brjuno fixed points

abstract:
  Let $f$ be a germ of holomorphic diffeomorphism of $\C^n$ fixing the origin
$O$, with $df_O$ diagonalizable. We prove that, under certain arithmetic
conditions on the eigenvalues of $df_O$ and some restrictions on the
resonances, $f$ is locally holomorphically linearizable if and only if there
exists a particular $f$-invariant complex manifold. Most of the classical
linearization results can be obtained as corollaries of our result.


title:
CMB Temperature Polarization Correlation and Primordial Gravitational
  Waves II: Wiener Filtering and Tests Based on Monte Carlo Simulations

abstract:
  In this paper we continue our study of CMB TE cross correlation as a source
of information about primordial gravitational waves. In an accompanying paper,
we considered the zero multipole method. In this paper we use Wiener filtering
of the CMB TE data to remove the density perturbation contribution to the TE
power spectrum. In principle this leaves only the contribution of PGWs. We
examine two toy experiments (one ideal and one more realistic), to see how well
they constrain PGWs using the TE power spectrum. We consider three tests
applied to a combination of observational data and data sets generated by Monte
Carlo simulations: (1) Signal-to-Noise test, (2) sign test, and (3) Wilcoxon
rank sum test. We compare these tests with each other and with the zero
multipole method. Finally, we compare the signal-to-noise ratio of TE
correlation measurements first with corresponding signal-to-noise ratios for BB
ground based measurements and later with current and future TE correlation
space measurements. We found that an ideal TE correlation experiment limited
only by cosmic variance can detect PGWs with a tensor-to-scalar ratio $r=0.3$
at 98% confidence level with the $S/N$ test, 93% confidence level with the sign
test, and 80% confidence level for the Wilcoxon rank sum test. We also compare
all results with corresponding results obtained using the zero multipole
method. We demonstrate that to measure PGWs by their contribution to the TE
cross correlation power spectrum in a realistic ground based experiment when
real instrumental noise is taken into account, the tensor-to-scalar ratio, $r$,
must be approximately four times larger. In the sense to detect PGWs, the zero
multipole method is the best, next best is the S/N test, then the sign test,
and the worst is the Wilcoxon rank sum test.


title: Time-Frequency Analysis of Fourier Integral Operators

abstract:
  We use time-frequency methods for the study of Fourier Integral operators
(FIOs). In this paper we shall show that Gabor frames provide very efficient
representations for a large class of FIOs. Indeed, similarly to the case of
shearlets and curvelets frames, the matrix representation of a Fourier Integral
Operator with respect to a Gabor frame is well-organized. This is used as a
powerful tool to study the boundedness of FIOs on modulation spaces. As special
cases, we recapture boundedness results on modulation spaces for
pseudo-differential operators with symbols in $M^{\infty,1}$, for some
unimodular Fourier multipliers and metaplectic operators.


abstract:
  Slow-light enhanced optical detection in liquid-infiltrated photonic crystals
is theoretically studied. Using a scattering-matrix approach and the
Wigner-Smith delay time concept, we show that optical absorbance benefits both
from slow-light phenomena as well as a high filling factor of the energy
residing in the liquid. Utilizing strongly dispersive photonic crystal
structures, we numerically demonstrate how liquid-infiltrated photonic crystals
facilitate enhanced light-matter interactions, by potentially up to an order of
magnitude. The proposed concept provides strong opportunities for improving
existing miniaturized absorbance cells for optical detection in lab-on-a-chip
systems.


title: Aggregation for Gaussian regression

abstract:
  This paper studies statistical aggregation procedures in the regression
setting. A motivating factor is the existence of many different methods of
estimation, leading to possibly competing estimators. We consider here three
different types of aggregation: model selection (MS) aggregation, convex (C)
aggregation and linear (L) aggregation. The objective of (MS) is to select the
optimal single estimator from the list; that of (C) is to select the optimal
convex combination of the given estimators; and that of (L) is to select the
optimal linear combination of the given estimators. We are interested in
evaluating the rates of convergence of the excess risks of the estimators
obtained by these procedures. Our approach is motivated by recently published
minimax results [Nemirovski, A. (2000). Topics in non-parametric statistics.
Lectures on Probability Theory and Statistics (Saint-Flour, 1998). Lecture
Notes in Math. 1738 85--277. Springer, Berlin; Tsybakov, A. B. (2003). Optimal
rates of aggregation. Learning Theory and Kernel Machines. Lecture Notes in
Artificial Intelligence 2777 303--313. Springer, Heidelberg]. There exist
competing aggregation procedures achieving optimal convergence rates for each
of the (MS), (C) and (L) cases separately. Since these procedures are not
directly comparable with each other, we suggest an alternative solution. We
prove that all three optimal rates, as well as those for the newly introduced
(S) aggregation (subset selection), are nearly achieved via a single
``universal'' aggregation procedure. The procedure consists of mixing the
initial estimators with weights obtained by penalized least squares. Two
different penalties are considered: one of them is of the BIC type, the second
one is a data-dependent $\ell_1$-type penalty.


title: Coxeter Groups and Wavelet Sets

abstract:
  A traditional wavelet is a special case of a vector in a separable Hilbert
space that generates a basis under the action of a system of unitary operators
defined in terms of translation and dilation operations. A
Coxeter/fractal-surface wavelet is obtained by defining fractal surfaces on
foldable figures, which tesselate the embedding space by reflections in their
bounding hyperplanes instead of by translations along a lattice. Although both
theories look different at their onset, there exist connections and
communalities which are exhibited in this semi-expository paper. In particular,
there is a natural notion of a dilation-reflection wavelet set. We prove that
dilation-reflection wavelet sets exist for arbitrary expansive matrix
dilations, paralleling the traditional dilation-translation wavelet theory.
There are certain measurable sets which can serve simultaneously as
dilation-translation wavelet sets and dilation-reflection wavelet sets,
although the orthonormal structures generated in the two theories are
considerably different.


title:
Hyperelliptic Jacobians as Billiard Algebra of Pencils of Quadrics:
  Beyond Poncelet Porisms

abstract:
  The thirty years old programme of Griffiths and Harris of understanding
higher-dimensional analogues of Poncelet-type problems and synthetic approach
to higher genera addition theorems has been settled and completed in this
paper. Starting with the observation of the billiard nature of some classical
constructions and configurations, we construct the billiard algebra, that is a
group structure on the set T of lines in $R^d$ simultaneously tangent to d-1
quadrics from a given confocal family. Using this tool, the related results of
Reid, Donagi and Knoerrer are further developed, realized and simplified. We
derive a fundamental property of T: any two lines from this set can be obtained
from each other by at most d-1 billiard reflections at some quadrics from the
confocal family. We introduce two hierarchies of notions: s-skew lines in T and
s-weak Poncelet trajectories, s = -1,0,...,d-2. The interrelations between
billiard dynamics, linear subspaces of intersections of quadrics and
hyperelliptic Jacobians developed in this paper enabled us to obtain
higher-dimensional and higher-genera generalizations of several classical genus
1 results: the Cayley's theorem, the Weyr's theorem, the Griffiths-Harris
theorem and the Darboux theorem.


title: A double supermirror monochromator for neutron instrumentation at LLB

abstract:
  The design and characteristics of a double supermirror monochromator for
neutron instrumentation at the Laboratoire Leon Brillouin is described. The aim
of this monochromator is to reduce the intense gamma-radiation produced by
conventional velocity selectors and to avoid a direct view of the guide while
keeping a comparable neutron transmission (higher than 70%). The monochromator
offers a continuous choice of wavelength selection in the range 0.5 to 2 nm.


title: Sensitivity of Nonrenormalizable Trajectories to the Bare Scale

abstract:
  Working in scalar field theory, we consider RG trajectories which correspond
to nonrenormalizable theories, in the Wilsonian sense. An interesting question
to ask of such trajectories is, given some fixed starting point in parameter
space, how the effective action at the effective scale, Lambda, changes as the
bare scale (and hence the duration of the flow down to Lambda) is changed. When
the effective action satisfies Polchinski's version of the Exact
Renormalization Group equation, we prove, directly from the path integral, that
the dependence of the effective action on the bare scale, keeping the
interaction part of the bare action fixed, is given by an equation of the same
form as the Polchinski equation but with a kernel of the opposite sign. We then
investigate whether similar equations exist for various generalizations of the
Polchinski equation. Using nonperturbative, diagrammatic arguments we find that
an action can always be constructed which satisfies the Polchinski-like
equation under variation of the bare scale. For the family of flow equations in
which the field is renormalized, but the blocking functional is the simplest
allowed, this action is essentially identified with the effective action at
Lambda = 0. This does not seem to hold for more elaborate generalizations.


title: Luminosity Dependence of the Quasar Clustering from SDSS DR5

abstract:
  43024 objects, which were primarily identified as quasars in SDSS DR5 and
have spectroscopic redshifts were used to study the luminosity dependence of
the quasar clustering with the help of two different techniques. The obtained
results reveal that brighter quasars are more clustered, but this dependence is
weak, which is in agreement with the results by Porciani & Norberg, 2006 and
theoretical predictions by Lidz et al., 2006.


title:
Electric quadrupole moment of the $5d^2 D_{3/2}$ state in $^{171}Yb^+$ :
  A relativistic coupled-cluster analysis

abstract:
  The electric quadrupole moment for the $5d^{2}D_{3/2}$ state of
$\mathrm{^{171}Yb^{+}}$, has been calculated using the relativistic
coupled-cluster method. Earlier a similar calculation was performed for the 4d
$^2D_{5/2}$ state of $\mathrm{^{88}Sr^{+}}$ which is the most accurate
determination to date {[}PRL, \textbf{96}, 193001 (2006)]. The present
calculation of the electric quadrupole moment of $\mathrm{^{171}Yb^{+}}$
yielded a value $2.157 ea_{0}^{2}$ where the experimental value is
$2.08(11)ea_{0}^{2}$; $a_{0}$ is the Bohr radius and $e$ the elementary charge.
We discuss in this paper our results in detail for $^{171}{\rm Yb}^{+}$ and
highlight the dominant correlation effects present. We have presented the
effect of inner core excitations and their contribution to the electric
quadrupole moment, which is a property sensitive to regions away from the
nucleus.


title: Unified description of resonance and decay phenomena

abstract:
  In the Feshbach projection operator formalism, resonance as well as decay
phenomena are described by means of the complex eigenvalues and eigenfunctions
of the non-Hermitian Hamilton operator $H_{\rm eff}$ that appears in an
intermediate stage of the formalism. The formalism can be applied for the
description of isolated resonances as well as for resonances in the overlapping
regime. Time asymmetry is related to the time operator which is a part of
$H_{\rm eff}$. An expression for the decay rates of resonance states is
derived. For isolated resonance states $\lambda$, this expression gives the
fundamental relation $\tau_\lambda = \hbar / \Gamma_\lambda$ between life time
and width of a resonance state. A similar relation holds for the average values
obtained for narrow resonances superposed by a smooth background term. In the
cross over between these two cases (regime of overlapping resonances), the
decay rate decreases monotonously as a function of increasing time.


title:
Evolution of coherence between the Jaynes - Cummings Eigenstates in the
  presence of repeated occupancy measurements: The case of resonant coupling

abstract:
  A two level system resonantly coupled to a single mode cavity field and
subject to ground state occupancy measurement like interaction is considered.
For this situation, the solution to the Lindblad master equation for the
density matrix is obtained with respect to the Jaynes Cummings eigenstate
representation. It is seen that, the rate of decoherence of the superposition
of the Jaynes Cummings eigenstates increases monotonically with the increase in
the occupancy measurement coupling up to a certain critical value (already
reported in the literature in a different context), whereas the rate decreases
with the increase in the measurement coupling beyond the same critical value.


title:
Constraints on Unparticle Interactions from Particle and Antiparticle
  Oscillations

abstract:
  We study unparticle effects on particle and antiparticle osillations in
meson-antimeson, and muonium-antimuonium systems. Unlike usual tree level
contributions to meson oscillations from heavy particle exchange with small
$\Gamma_{12}$, the unparticle may have sizeable contributions to both $M_{12}$
and $\Gamma_{12}$ due to fractional dimension $d_\U$ of the unparticle. We find
that very stringent constraints on the unparticle and particle interactions can
be obtained. If unparticle effect dominates the contributions (which may happen
in $D^0-\bar D^0$ mixing) to meson mixing parameters $x$ and $y$, we find that
$x/y =\cot(\pi d_\U)$. Interesting constraints on unparticle and particle
interactions can also be obtained using muonion and antimuonion oscillation
data. We also comment on unparticle effects on CP violation in meson
oscillations.


title: Unimodular lattices in dimensions 14 and 15 over the Eisenstein integers

abstract:
  All indecomposable unimodular hermitian lattices in dimensions 14 and 15 over
the ring of integers in $\mathbb{Q}(\sqrt{-3})$ are determined. Precisely one
lattice in dimension 14 and two lattices in dimension 15 have minimal norm 3.


title: Asymptotics of eigenfunctions on plane domains

abstract:
  We consider a family of domains $(\Omega_N)_{N>0}$ obtained by attaching an
$N\times 1$ rectangle to a fixed set $\Omega_0 = \{(x,y): 0<y<1,
-\phi(y)<x<0\}$, for a Lipschitz function $\phi\geq 0$. We derive full
asymptotic expansions, as $N\to\infty$, for the $m$th Dirichlet eigenvalue (for
any fixed $m$) and for the associated eigenfunction on $\Omega_N$. The second
term involves a scattering phase arising in the Dirichlet problem on the
infinite domain $\Omega_\infty$. We determine the first variation of this
scattering phase, with respect to $\phi$, at $\phi\equiv 0$. This is then used
to prove sharpness of results, obtained previously by the same authors, about
the location of extrema and nodal line of eigenfunctions on convex domains.


title:
Regression for partially observed variables and nonparametric quantiles
  of conditional probabilities

abstract:
  Efficient estimation under bias sampling, censoring or truncation is a
difficult question which has been partially answered and the usual estimators
are not always consistent. Several biased designs are considered for models
with variables $(X,Y)$ where $Y$ is an indicator and $X$ an explanatory
variable, or for continuous variables $(X,Y)$. The identifiability of the
models are discussed. New nonparametric estimators of the regression functions
and conditional quantiles are proposed.


title: Conformal changes of generalized complex structures

abstract:
  A conformal change of $TM\oplus T^*M$ is a morphism of the form
$(X,\alpha)\mapsto(X,e^\tau\alpha)$ $(X\in TM,\alpha\in T^*M,\tau\in
C^\infty(M))$. We characterize the generalized almost complex and almost
Hermitian structures that are locally conformal to integrable and to
generalized K\"ahler structures, respectively, and give examples of such
structures.


title:
Harmonic sections of tangent bundles equipped with Riemannian
  $g$-natural metrics

abstract:
  Let $(M,g)$ be a Riemannian manifold. When $M$ is compact and the tangent
bundle $TM$ is equipped with the Sasaki metric $g^s$, the only vector fields
which define harmonic maps from $(M,g)$ to $(TM,g^s)$, are the parallel ones.
The Sasaki metric, and other well known Riemannian metrics on $TM$, are
particular examples of $g$-natural metrics. We equip $TM$ with an arbitrary
Riemannian $g$-natural metric $G$, and investigate the harmonicity of a vector
field $V$ of $M$, thought as a map from $(M,g)$ to $(TM,G)$. We then apply this
study to the Reeb vector field and, in particular, to Hopf vector fields on
odd-dimensional spheres.


title: Alpha-determinant cyclic modules and Jacobi polynomials

abstract:
  We study the cyclic $U(\mathfrak{gl}_n)$-module generated by the $l$-th power
of the $\alpha$-determinant. When $l$ is a non-negative integer, for all but
finite exceptional values of $alpha$, one shows that this cyclic module is
isomorphic to the $n$-th tensor space $(S^l(\mathbb{C}^n))^{\otimes n}$ of the
symmetric $l$-th tensor space of $\mathbb{C}^n$. If $alpha$ is exceptional,
then the structure of the module changes drastically, i.e. some irreducible
representations which are the irreducible components of the decomposition of
$(S^l(\mathbb{C}^n))^{\otimes n}$ disappear in the decomposition of the cyclic
module. The degeneration of each isotypic component of the cyclic module is
described by a matrix whose size is given by a Kostka number and entries are
polynomials in $alpha$ with rational coefficients. As a special case, we
determine the matrix in a full of the detail for the case where $n=2$; the
matrix becomes a scalar and is essentially given by the classical Jacobi
polynomial. Moreover, we prove that these polynomials are unitary.


title: Generalized Israel Junction Conditions for a Fourth-Order Brane World

abstract:
  We discuss a general fourth-order theory of gravity on the brane. In general,
the formulation of the junction conditions (except for Euler characteristics
such as Gauss-Bonnet term) leads to the higher powers of the delta function and
requires regularization. We suggest the way to avoid such a problem by imposing
the metric and its first derivative to be regular at the brane, while the
second derivative to have a kink, the third derivative of the metric to have a
step function discontinuity, and no sooner as the fourth derivative of the
metric to give the delta function contribution to the field equations.
Alternatively, we discuss the reduction of the fourth-order gravity to the
second-order theory by introducing an extra tensor field. We formulate the
appropriate junction conditions on the brane. We prove the equivalence of both
theories. In particular, we prove the equivalence of the junction conditions
with different assumptions related to the continuity of the metric along the
brane.


title: Modelling highway-traffic headway distributions using superstatistics

abstract:
  We study traffic clearance distributions (i.e., the instantaneous gap between
successive vehicles) and time headway distributions by applying Beck and
Cohen's superstatistics. We model the transition from free phase to congested
phase with the increase of vehicle density as a transition from the Poisson
statistics to that of the random matrix theory. We derive an analytic
expression for the spacing distributions that interpolates from the Poisson
distribution and Wigner's surmise and apply it to the distributions of the nett
distance and time gaps among the succeeding cars at different densities of
traffic flow. The obtained distribution fits the experimental results for
single-vehicle data of the Dutch freeway A9 and the German freeway A5.


title: Lepton masses and mixings in orbifold models with three Higgs families

abstract:
  We analyse the phenomenological viability of heterotic Z(3) orbifolds with
two Wilson lines, which naturally predict three supersymmetric families of
matter and Higgs fields. Given that these models can accommodate realistic
scenarios for the quark sector avoiding potentially dangerous flavour-changing
neutral currents, we now address the leptonic sector, finding that viable
orbifold configurations can in principle be obtained. In particular,it is
possible to accomodate present data on charged lepton masses, while avoiding
conflict with lepton flavour-violating decays. Concerning the generation of
neutrino masses and mixings, we find that Z(3) orbifolds offer several
interesting possibilities.


title:
On the Fluctuation Relation for Nose-Hoover Boundary Thermostated
  Systems

abstract:
  We discuss the transient and steady state fluctuation relation for a
mechanical system in contact with two deterministic thermostats at different
temperatures. The system is a modified Lorentz gas in which the fixed
scatterers exchange energy with the gas of particles, and the thermostats are
modelled by two Nos\'e-Hoover thermostats applied at the boundaries of the
system. The transient fluctuation relation, which holds only for a precise
choice of the initial ensemble, is verified at all times, as expected. Times
longer than the mesoscopic scale, needed for local equilibrium to be settled,
are required if a different initial ensemble is considered. This shows how the
transient fluctuation relation asymptotically leads to the steady state
relation when, as explicitly checked in our systems, the condition found in
[D.J. Searles, {\em et al.}, J. Stat. Phys. 128, 1337 (2007)], for the validity
of the steady state fluctuation relation, is verified. For the steady state
fluctuations of the phase space contraction rate $\zL$ and of the dissipation
function $\zW$, a similar relaxation regime at shorter averaging times is
found. The quantity $\zW$ satisfies with good accuracy the fluctuation relation
for times larger than the mesoscopic time scale; the quantity $\zL$ appears to
begin a monotonic convergence after such times. This is consistent with the
fact that $\zW$ and $\zL$ differ by a total time derivative, and that the tails
of the probability distribution function of $\zL$ are Gaussian.


title:
Semigroup algebras of submonoids of polycyclic-by-finite groups and
  maximal orders

abstract:
  Necessary and sufficient conditions are given for a prime Noetherian algebra
K[S] of a submonoid S of a polycyclic-by-finite group G to be a maximal order.
These conditions are entirely in terms of the monoid S. This extends earlier
results of Brown concerned with the group ring case and of the authors for the
case where K[S] satisfies a polynomial identity.


title: The combinatorics of Bogoliubov's recursion in renormalization

abstract:
  We describe various combinatorial aspects of the Birkhoff-Connes-Kreimer
factorization in perturbative renormalisation. The analog of Bogoliubov's
preparation map on the Lie algebra of Feynman graphs is identified with the
pre-Lie Magnus expansion. Our results apply to any connected filtered Hopf
algebra, based on the pro-nilpotency of the Lie algebra of infinitesimal
characters.


title: Outliers in dynamic factor models

abstract:
  Dynamic factor models have a wide range of applications in econometrics and
applied economics. The basic motivation resides in their capability of reducing
a large set of time series to only few indicators (factors). If the number of
time series is large compared to the available number of observations then most
information may be conveyed to the factors. This way low dimension models may
be estimated for explaining and forecasting one or more time series of
interest. It is desirable that outlier free time series be available for
estimation. In practice, outlying observations are likely to arise at unknown
dates due, for instance, to external unusual events or gross data entry errors.
Several methods for outlier detection in time series are available. Most
methods, however, apply to univariate time series while even methods designed
for handling the multivariate framework do not include dynamic factor models
explicitly. A method for discovering outliers occurrences in a dynamic factor
model is introduced that is based on linear transforms of the observed data.
Some strategies to separate outliers that add to the model and outliers within
the common component are discussed. Applications to simulated and real data
sets are presented to check the effectiveness of the proposed method.


title:
Five-dimensional PPN formalism and experimental test of Kaluza-Klein
  theory

abstract:
  The parametrized post Newtonian formalism for 5-dimensional metric theories
with a compact extra dimension is developed. The relation of the 5-dimensional
and 4-dimensional formulations is then analyzed, in order to compare the higher
dimensional theories of gravity with experiments. It turns out that the value
of post Newtonian parameter $\gamma$ in the reduced 5-dimensional Kaluza-Klein
theory is two times smaller than that in 4-dimensional general relativity. The
departure is due to the existence of an extra dimension in the Kaluza-Klein
theory. Thus the confrontation between the reduced 4-dimensional formalism and
Solar system experiments raises a severe challenge to the classical
Kaluza-Klein theory.


title: An Extension of Alzer's Inequality

abstract:
  In this article, we obtain two interesting general inequalities concerning
Riemman sums of convex functions, which in particular, sharpen Alzer's
inequality and give a suitable converse for it.


title: Bayesian inference with rescaled Gaussian process priors

abstract:
  We use rescaled Gaussian processes as prior models for functional parameters
in nonparametric statistical models. We show how the rate of contraction of the
posterior distributions depends on the scaling factor. In particular, we
exhibit rescaled Gaussian process priors yielding posteriors that contract
around the true parameter at optimal convergence rates. To derive our results
we establish bounds on small deviation probabilities for smooth stationary
Gaussian processes.


title:
Mass and angular-momentum inequalities for axi-symmetric initial data
  sets I. Positivity of mass

abstract:
  We extend the validity of Brill's axisymmetric positive energy theorem to all
asymptotically flat initial data sets with positive scalar curvature on simply
connected manifolds.


title: Some New Inequalities Between Important Means

abstract:
  In this paper, mainly using the convexity of the function
$\frac{a^x-b^x}{c^x-d^x}$ and convexity or concavity of the function
$\ln\frac{a^x-b^x}{c^x-d^x}$ on the real line, where $a>b\geq c>d>0$ are fixed
real numbers, we obtain some important relations between various important
means of these numbers. Also, we apply the obtained results to Ky Fan type
inequalities and get some new refinements.


title: Probing Elemental Abundances in SNR 1987A Using XMM-Newton

abstract:
  We report on the latest (2007 Jan) observations of supernova remnant (SNR)
1987A from the XMM-Newton mission. Since the 2003 May observations of Haberl et
al. (2006), 11 emission lines have experienced increases in flux by factors ~ 3
to 10, with the 775 eV line of O VIII showing the greatest increase; we have
observed 6 lines of Fe XVII and Fe XVIII previously unreported by XMM-Newton. A
two-shock model representing plasmas in non-equilibrium ionization is fitted to
the EPIC-pn spectra, yielding temperatures of ~ 0.4 and ~ 3 keV, as well as
elemental abundances for N, O, Ne, Mg, Si, S and Fe. We demonstrate that the
abundance ratio of N and O can be constrained to less than ~20% accuracy.
Within the same confidence interval, the same analysis suggests that the C+N+O
abundance varies from ~ 1.1 to 1.4 X 10^-4. Normalizing our obtained abundances
by the Large Magellanic Cloud (LMC) values of Hughes, Hayashi & Koyama (1998),
we find that O, Ne, Mg and Fe are under-abundant, while Si and S are
over-abundant, consistent with the findings of Aschenbach (2007). Such a result
has implications for both the single-star and binary accretion/merger models
for the progenitor of SNR 1987A. In the context of the binary merger scenario
proposed by Morris & Podsiadlowski (2006, 2007), material forming the inner,
equatorial ring was expelled after the merger, implying that either our derived
Fe abundance is inconsistent with typical LMC values or that iron is
under-abundant at the site of the progenitor star of SNR 1987A.


title:
Spiral Galaxies Rotation Curves with a Logarithmic Corrected Newtonian
  Gravitational Potential

abstract:
  We analyze the rotation curves of 10 spiral galaxies with a newtonian
potential corrected with an extra logarithmic term, using a disc modelization
for the spiral galaxies. There is a new constant associated with the extra term
in the potential. The rotation curve of the chosen sample of spiral galaxies is
well reproduced for a given range of the new constant. It is argued that this
correction can have its origin from string configurations. The compatibility of
this correction with local physics is discussed.


title:
Weak convergence of Metropolis algorithms for non-i.i.d. target
  distributions

abstract:
  In this paper, we shall optimize the efficiency of Metropolis algorithms for
multidimensional target distributions with scaling terms possibly depending on
the dimension. We propose a method for determining the appropriate form for the
scaling of the proposal distribution as a function of the dimension, which
leads to the proof of an asymptotic diffusion theorem. We show that when there
does not exist any component with a scaling term significantly smaller than the
others, the asymptotically optimal acceptance rate is the well-known 0.234.


title: Indirect search for Dark Matter with the ANTARES neutrino telescope

abstract:
  Relic neutralinos produced after the Big Bang are favoured candidates for
Dark Matter. They can accumulate at the centre of massive celestial objects
like our Sun. Their annihilation can result in a high-energy neutrino flux that
could be detectable as a localised emission with earth-based neutrino
telescopes like ANTARES. In this paper a brief overview of the prospects of the
indirect search for Dark Matter particles with the ANTARES detector will be
given. The analysis method and expected performance for the detection of the
expected neutrinos will be discussed.


title: Some Results on Inverse Scattering

abstract:
  A review of some of the author's results in the area of inverse scattering is
given. The following topics are discussed: 1) Property $C$ and applications, 2)
Stable inversion of fixed-energy 3D scattering data and its error estimate, 3)
Inverse scattering with ''incomplete`` data, 4) Inverse scattering for
inhomogeneous Schr\"odinger equation, 5) Krein's inverse scattering method, 6)
Invertibility of the steps in Gel'fand-Levitan, Marchenko, and Krein inversion
methods, 7) The Newton-Sabatier and Cox-Thompson procedures are not inversion
methods, 8) Resonances: existence, location, perturbation theory, 9) Born
inversion as an ill-posed problem, 10) Inverse obstacle scattering with
fixed-frequency data, 11) Inverse scattering with data at a fixed energy and a
fixed incident direction, 12) Creating materials with a desired refraction
coefficient and wave-focusing properties.


title: On invariant measures of stochastic recursions in a critical case

abstract:
  We consider an autoregressive model on $\mathbb{R}$ defined by the recurrence
equation $X_n=A_nX_{n-1}+B_n$, where $\{(B_n,A_n)\}$ are i.i.d. random
variables valued in $\mathbb{R}\times\mathbb{R}^+$ and $\mathbb {E}[\log
A_1]=0$ (critical case). It was proved by Babillot, Bougerol and Elie that
there exists a unique invariant Radon measure of the process $\{X_n\}$. The aim
of the paper is to investigate its behavior at infinity. We describe also
stationary measures of two other stochastic recursions, including one arising
in queuing theory.


title:
Partition Function for Two-Dimensional Nearest Neighbour Ising Model in
  a Non-Zero Magnetic Field for a Square Lattice of 16 Sites

abstract:
  An explicit expression for the partition function of two-dimensional nearest
neighbour Ising models in the presence of a magnetic field is derived by a
systematic enumeration of all the spin configurations pertaining to a square
lattice of sixteen sites. The critical temperature is shown to be in excellent
agreement with the reported values while the corresponding dimensionless
magnetic field is obtained as 0.004.


title:
Quasi-stationary regime of a branching random walk in presence of an
  absorbing wall

abstract:
  A branching random walk in presence of an absorbing wall moving at a constant
velocity $v$ undergoes a phase transition as the velocity $v$ of the wall
varies. Below the critical velocity $v_c$, the population has a non-zero
survival probability and when the population survives its size grows
exponentially. We investigate the histories of the population conditioned on
having a single survivor at some final time $T$. We study the quasi-stationary
regime for $v<v_c$ when $T$ is large. To do so, one can construct a modified
stochastic process which is equivalent to the original process conditioned on
having a single survivor at final time $T$. We then use this construction to
show that the properties of the quasi-stationary regime are universal when
$v\to v_c$. We also solve exactly a simple version of the problem, the
exponential model, for which the study of the quasi-stationary regime can be
reduced to the analysis of a single one-dimensional map.


title: Wesson's IMT with a Weylian bulk

abstract:
  The foundations of Wesson's induced matter theory are analyzed. It is shown
that the 5D empty bulk must be regarded rather as a Weylian space than as a
Riemannian one.The framework of a Weyl-Dirac version of Wesson's theory is
elaborated and discussed. The bulk possesses in addition to the metric tensor a
Weylian connection vector as well Dirac's gauge function; there are no sources
(mass, current) in the bulk. On the 4D brane one obtains a geometrically based
unified theory of gravitation and electromagnetism with mass, currents and
equations induced by the 5D bulk


title: A MST algorithm for source detection in gamma-ray images

abstract:
  We developed a source detection algorithm based on the Minimal Spanning Tree
(MST), that is a graph-theoretical method useful for finding clusters in a
given set of points. This algorithm is applied to gamma-ray bidimensional
images where the points correspond to the arrival direction of photons, and the
possible sources are associated with the regions where they clusterize. Some
filters to select these clusters and to reduce the spurious detections are
introduced. An empirical study of the statistical properties of MST on random
fields is carried in order to derive some criteria to estimate the best filter
values. We introduce also two parameters useful to verify the goodness of
candidate sources. To show how the MST algorithm works in the practice, we
present an application to an EGRET observation of the Virgo field, at high
galactic latitude and with a low and rather uniform background, in which
several sources are detected.


title: Universality class of the pair contact process with diffusion

abstract:
  The pair contact process with diffusion (PCPD) is studied with a standard
Monte Carlo approach and with simulations at fixed densities. A standard
analysis of the simulation results, based on the particle densities or on the
pair densities, yields inconsistent estimates for the critical exponents.
However, if a well-chosen linear combination of the particle and pair densities
is used, leading corrections can be suppressed, and consistent estimates for
the independent critical exponents delta=0.16(2), beta=0.28(2) and z=1.58 are
obtained. Since these estimates are also consistent with their values in
directed percolation (DP), we conclude that PCPD falls in the same universality
class as DP.


title:
Exponential mixing for finite-dimensional approximations of the
  Schr\"odinger equation with multiplicative noise

abstract:
  We study the ergodicity of finite-dimensional approximations of the
Schr\"odinger equation. The system is driven by a multiplicative scalar noise.
Under general assumptions over the distribution of the noise, we show that the
system has a unique stationary measure $\mu$ on the unit sphere $S$ in $\C^n$,
and $\mu$ is absolutely continuous with respect to the Riemannian volume on
$S$. Moreover, for any initial condition in $S$, the solution converges
exponentially fast to the measure $\mu$ in the variational norm.


title:
Measurement of the parity-violating triton emission asymmetry in the
  reaction 6Li(n,alfa)3H with polarised cold neutrons

abstract:
  We describe measurements of the parity-violating (P-odd) triton emission
asymmetry coefficient in the 6Li(n,alfa)3H reaction with polarised cold
neutrons. Experiments were carried out at the Petersburg Nuclear Physics
Institute (Gatchina, Russia) and at the Institut Laue-Langevin (Grenoble,
France). We employed an ionisation chamber in a configuration allowing us to
suppress the left-right asymmetry well below 10^(-8). A test for a false
asymmetry due to eventual target impurities ("zero test") resulted in the value
(0.0+-0.5)x10^(-8). As final result we obtained P-odd effect
(-8.6+-2.0)x10^(-8).


title:
Magnetic Field Distribution Due to Domain Walls in Unconventional
  Superconductors

abstract:
  Steady-state properties of Bloch domain wall (DW) in superconducting
ferromagnet (SCFM) are studied. The distribution of magnetic field above and
below the surface of the SCFM due to the permanent magnetization supercurrent
flowing in the DW plane is calculated by solving Maxwell equations supplemented
by London equation. It is shown that part of the magnetic flux of the two
neighboring domains closures in the nearest vicinity of the surface of the
sample giving rise to declination of the line of the force from being parallel
to the DW plane. As a result, the value of the normal component of magnetic
field at the surface of the sample reaches only half of the value of the bulk
magnetic flux. At the distances of the order of value of London penetration
depth the magnetic field decreases as inverse power law due to the long-range
character of dipole-dipole interaction. The last two circumstances are
important for comparison the calculated magnetic field with the data obtained
by the methods on measurement of normal component of magnetic field, e. g. Hall
probe technique, aimed to confirm the existence of magnetic order parameter in
unconventional superconductor.


title: Optical Spectroscopy of Active Galactic Nuclei in SA57

abstract:
  The cosmological evolution of X-ray-selected and optically selected Active
Galactic Nuclei (AGNs) show different behaviours interpreted in terms of two
different populations. The difference is evident mainly for low luminosity AGNs
(LLAGNs), many of which are lost by optical photometric surveys. We are
conducting a spectroscopical study of a composite sample of AGN candidates
selected in SA57 following different searching techniques, to identify low
luminosity AGNs and break down the sample into different classes of objects.
AGN candidates were obtained through optical variability and/or X-ray emission.
Of special interest are the extended variable objects, which are expected to be
galaxies hosting LLAGNs. Among the 26 classified objects a fair number (9) show
typical AGN spectra. 10 objects show Narrow Emission Line Galaxy spectra, and
in most of them (8/10) optical variability suggests the presence of LLAGNs.


title: Coupling a branching process to an infinite dimensional epidemic process

abstract:
  Branching process approximation to the initial stages of an epidemic process
has been used since the 1950's as a technique for providing stochastic
counterparts to deterministic epidemic threshold theorems. One way of
describing the approximation is to construct both branching and epidemic
processes on the same probability space, in such a way that their paths
coincide for as long as possible. In this paper, it is shown, in the context of
a Markovian model of parasitic infection, that coincidence can be achieved with
asymptotically high probability until o(N^{2/3}) infections have occurred,
where N denotes the total number of hosts.


title:
Nature versus Nurture: The curved spine of the galaxy cluster X-ray
  luminosity -- temperature relation

abstract:
  The physical processes that define the spine of the galaxy cluster X-ray
luminosity -- temperature (L-T) relation are investigated using a large
hydrodynamical simulation of the Universe. This simulation models the same
volume and phases as the Millennium Simulation and has a linear extent of 500
h^{-1} Mpc. We demonstrate that mergers typically boost a cluster along but
also slightly below the L-T relation. Due to this boost we expect that all of
the very brightest clusters will be near the peak of a merger. Objects from
near the top of the L-T relation tend to have assembled much of their mass
earlier than an average halo of similar final mass. Conversely, objects from
the bottom of the relation are often experiencing an ongoing or recent merger.


title:
Charge asymmetry for electron (positron)-proton elastic scattering at
  large angle

abstract:
  Charge asymmetry in electron (positron) scattering arises from the
interference of the Born amplitude and the box-type amplitude corresponding to
two virtual photons exchange. It can be extracted from electron proton and
positron proton scattering experiments, in the same kinematical conditions.
Considering the virtual photon Compton scattering tensor, which contributes to
the box-type amplitude, we separate proton and inelastic contributions in the
intermediate state and parametrize the proton form-factors as the sum of a pure
QED term and a strong interaction term. Arguments based on analyticity are
given in favor of cancellation of contributions from proton strong interaction
form factors and of inelastic intermediate states in the box type amplitudes.
In frame of this model, with a realistic expression for nucleon form-factors,
numerical estimations are given for moderately high energies.


title: Nuclear matter in the chiral limit and the in-medium chiral condensate

abstract:
  We investigate nuclear matter, i.e. the nuclear equation-of-state (EOS) as
well as the relativistic mean fields in the chiral limit. The investigations
are based on a chiral nucleon-nucleon EFT interaction where the explicit and
implicit pion mass dependence is known up to next-to-leading order. The nuclear
bulk properties are found to remain fairly stable in the chiral limit. Based on
the same interaction the in-medium scalar condensate is derived, both in
Hartree-Fock approximation as well as from the Brueckner G-matrix, making
thereby use of the Hellman-Feynman theorem. Short distance physics which
determines the reduction of the in-medium nucleon mass is found to play only a
minor role for the reduction of the chiral condensate.


title: Population trapping due to cavity losses

abstract:
  In population trapping the occupation of a decaying quantum level keeps a
constant non-zero value. We show that an atom-cavity system interacting with an
environment characterized by a non-flat spectrum, in the non-Markovian limit,
exhibits such a behavior, effectively realizing the preservation of
nonclassical states against dissipation. Our results allow to understand the
role of cavity losses in hybrid solid state systems and pave the way to the
proper description of leakage in the recently developed cavity quantum
electrodynamic systems.


title: Monomial integrals on the classical groups

abstract:
  This paper presents a powerfull method to integrate general monomials on the
classical groups with respect to their invariant (Haar) measure. The method has
first been applied to the orthogonal group in [J. Math. Phys. 43, 3342 (2002)],
and is here used to obtain similar integration formulas for the unitary and the
unitary symplectic group. The integration formulas turn out to be of similar
form. They are all recursive, where the recursion parameter is the number of
column (row) vectors from which the elements in the monomial are taken. This is
an important difference to other integration methods. The integration formulas
are easily implemented in a computer algebra environment, which allows to
obtain analytical expressions very efficiently. Those expressions contain the
matrix dimension as a free parameter.

categories: math-ph cond-mat.mes-hall math.MP math.RT


title: Spectral Properties and Linear Stability of Self-Similar Wave Maps

abstract:
  We study co--rotational wave maps from $(3+1)$--Minkowski space to the
three--sphere $S^3$. It is known that there exists a countable family $\{f_n\}$
of self--similar solutions. We investigate their stability under linear
perturbations by operator theoretic methods. To this end we study the spectra
of the perturbation operators, prove well--posedness of the corresponding
linear Cauchy problem and deduce a growth estimate for solutions. Finally, we
study perturbations of the limiting solution which is obtained from $f_n$ by
letting $n \to \infty$.


title:
The red and blue galaxy populations in the GOODS field: evidence for an
  excess of red dwarfs

abstract:
  We study the evolution of the galaxy population up to z\sim3 as a function of
its colour properties. In particular, luminosity functions and luminosity
densities have been derived as a function of redshift for the blue/late and
red/early populations. We use data from the GOODS-MUSIC catalogue which have
typical magnitude limits z<26 and Ks<23.5 for most of the sample. About 8% of
the galaxies have spectroscopic redshifts; the remaining have well calibrated
photometric redshifts derived from the extremely wide multi-wavelength coverage
in 14 bands (from the U band to the Spitzer 8 \mu m band). We have derived a
catalogue of galaxies complete in rest-frame B-band, which has been divided in
two subsamples according to their rest-frame U-V colour (or derived specific
star formation rate, SSFR) properties. We confirm a bimodality in the U-V
colour and SSFR of the galaxy sample up to z\sim 3. This bimodality is used to
compute the LFs of the blue/late and red/early subsamples. The LFs of the
blue/late and total samples are well represented by steep Schechter functions
evolving in luminosity with increasing redshifts. The volume density of the LFs
of the red/early populations decreases with increasing redshift. The shape of
the red/early LFs shows an excess of faint red dwarfs with respect to the
extrapolation of a flat Schechter function and can be represented by the sum of
two Schechter functions. Our model for galaxy formation in the hierarchical
clustering scenario, which also includes external feedback due to a diffuse UV
background, shows a general broad agreement with the LFs of both populations,
the larger discrepancies being present at the faint end for the red population.
Hints on the nature of the red dwarf population are given on the basis of their
stellar mass and spatial distributions.


title: Flavour symmetries and SUSY soft breaking in the LHC era

abstract:
  The so-called supersymmetric flavour problem does not exist in isolation to
the Standard Model flavour problem. We show that a realistic flavour symmetry
can simultaneously solve both problems without ad hoc modifications of the SUSY
model. Furthermore, departures from the SM expectations in these models can be
used to discriminate among different possibilities. In particular we present
the expected values for the electron EDM in a flavour model solving the
supersymmetric flavour and CP problems.


title:
The Magellanic Clouds as a template for the study of stellar populations
  and galaxy interactions

abstract:
  The Magellanic System represents one of the best places to study the
formation and evolution of galaxies. Photometric surveys of various depths,
areas and wavelengths have had a significant impact on our understanding of the
system; however, a complete picture is still lacking. VMC (the VISTA
near-infrared YJKs survey of the Magellanic System) will provide new data to
derive the spatially resolved star formation history and to construct a
three-dimensional map of the system. These data combined with those from other
ongoing and planned surveys will give us an absolutely unique view of the
system opening up the doors to truly new science!


title:
Intrinsic avalanches and collective phenomena in a Mn(II)-free radical
  ferrimagnetic chain

abstract:
  Magnetic hysteresis loops below 300 mK on single crystals of the Mn(II) -
nitronyl nitroxide free radical chain (Mn(hfac)_2({\it R})-3MLNN) present
abrupt reversals of the magnetization, or avalanches. We show that, below 200
mK, the avalanches occur at a constant field, independent of the sample and so
propose that this avalanche field is an intrinsic property. We compare this
field to the energy barrier existing in the sample and conclude that the
avalanches are provoked by multiple nucleation of domain-walls along the
chains. The different avalanche field observed in the zero field cooled
magnetization curves suggests that the avalanche mechanisms are related to the
competition between ferromagnetic and antiferromagnetic order in this compound.


title: What we have learned so far from 3-fluid hydrodynamics

abstract:
  Available data on heavy-ion collisions at AGS and SPS energies are analyzed
using a 3-fluid dynamical model within a purely hadronic scenario. We
investigate the problems met in reproducing these data within this scheme. In
particular, we try to indicate those data which could point towards the
occurrence of a phase transition into the quark-gluon phase. We also discuss
the success of the model in reproducing the transverse-mass spectra of various
hadrons. We argue that the simultaneous reproduction of the inverse-slope
parameters of all considered particles may imply that these particles belong to
the same hydrodynamic flow at the instant of their freeze-out rather than that
it signals the onset of a phase transition.


title: On measuring standards in Weyl's geometry

abstract:
  In Weyl's geometry the nonintegrability problem and difficulties in defining
measuring standards are reconsidered. Approaches removing the nonintegrability
of lengthin in the interior of atoms are given, so that atoms may serve as
measuring standards. The Weyl space become a well founded framework for
classical theories of gravitation and electromagnetism,


title: Some forgotten features of the Bose Einstein Correlations

abstract:
  Notwithstanding the visible maturity of the subject of Bose-Einstein
Correlations (BEC), as witnessed nowadays, we would like to bring to ones
attention two points, which apparently did not received attention they deserve:
the problem of the choice of the form of $C_2(Q)$ correlation function when
effects of partial coherence of the hadronizing source are to be included and
the feasibility to model effects of Bose-Einstein statistics, in particular the
BEC, by direct numerical simulations.


title: Rational subsets of polycyclic monoids and valence automata

abstract:
  We study the classes of languages defined by valence automata with rational
target sets (or equivalently, regular valence grammars with rational target
sets), where the valence monoid is drawn from the important class of polycyclic
monoids. We show that for polycyclic monoids of rank 2 or more, such automata
accept exactly the context-free languages. For the polycyclic monoid of rank 1
(that is, the bicyclic monoid), they accept a class of languages strictly
including the partially blind one-counter languages. Key to the proof is a
description of the rational subsets of polycyclic and bicyclic monoids, other
consequences of which include the decidability of the rational subset
membership problem for these monoids, and the closure of the class of rational
subsets under intersection and complement.


title:
The Milky Way's Kiloparsec Scale Wind: A Hybrid Cosmic-Ray and Thermally
  Driven Outflow

abstract:
  We apply a wind model, driven by combined cosmic-ray and thermal-gas
pressure, to the Milky Way, and show that the observed Galactic diffuse soft
X-ray emission can be better explained by a wind than by previous static gas
models. We find that cosmic-ray pressure is essential to driving the observed
wind. Having thus defined a "best-fit" model for a Galactic wind, we explore
variations in the base parameters and show how the wind's properties vary with
changes in gas pressure, cosmic-ray pressure and density. We demonstrate the
importance of cosmic rays in launching winds, and the effect cosmic rays have
on wind dynamics. In addition, this model adds support to the hypothesis of
Breitschwerdt and collaborators that such a wind may help explain the
relatively small gradient observed in gamma-ray emission as a function of
galactocentric radius.


title:
Quasi-gaussian velocity distribution of a vibrated granular bilayer
  system

abstract:
  We show by using a Discrete Element Method that a bilayer of vibrated
granular bidisperse spheres exhibits the striking feature that the horizontal
velocity distribution of the top layer particles has a quasi-Gaussian shape,
whereas that of the bottom layer is far from Gaussian. We examine in detail the
relevance of all physical parameters (acceleration of the bottom plate, mass
ratio, layer coverage). Moreover, a microscopic analysis of the trajectories
and the collision statistics reveal how the mechanism of randomization.


title: Updated Constraints from B Physics on the MSSM and the NMSSM

abstract:
  We update constraints from B physics observables on the parameters of the
MSSM and the NMSSM, combining them with LEP constraints. Presently available SM
and Susy radiative corrections are included in the calculations, which will be
made public in the form of a Fortran code. Results for the tan(beta) and
M_{H^+} dependence of b -> s gamma are presented, as well as constraints on the
NMSSM specific case of a light CP odd Higgs scalar. We find that the latter are
essentially due to B_s -> mu^+ mu^-, but they do not exclude this possibility.


title:
A fretting crack initiation prediction taking into account the surface
  roughness and the crack nucleation process volume

abstract:
  This paper presents an experimental study of the fretting crack nucleation
threshold, expressed in terms of loading conditions, with a cylinder/plane
contact. The studied material is a damage tolerant aluminium alloy widely used
in the aerospace application. Since in industrial problems, the surface quality
is often variable, the impact of a unidirectional roughness is investigated via
varying the roughness of the counter body in the fretting experiments. As
expected, experimental results show a large effect of the contact roughness on
the crack nucleation conditions. Rationalisation of the crack nucleation
boundary independently of the studied roughnesses was successfully obtained by
introducing the concept of effective contact area. This does show that the
fretting crack nucleation of the studied material can be efficiently described
by the local effective loadings inside the contact. Analytical prediction of
the crack nucleation is presented with the Smith-Watson-Topper (SWT) parameter
and size effect is also studied and discussed.


title:
The interplay between hydrodynamic and Brownian fluctuations in
  sedimenting colloidal suspensions

abstract:
  We apply a hybrid Molecular Dynamics and mesoscopic simulation technique to
study the steady-state sedimentation of hard sphere particles for Peclet
numbers (Pe) ranging from 0.08 to 12. Hydrodynamic back-flow causes a reduction
of the average sedimentation velocity relative to the Stokes velocity. We find
that this effect is independent of Pe number. Velocity fluctuations show the
expected effects of thermal fluctuations at short correlation times. At longer
times, non-equilibrium hydrodynamic fluctuations are visible, and their
character appears to be independent of the thermal fluctuations. The
hydrodynamic fluctuations dominate the diffusive behavior even for modest Pe
number, while conversely the short-time fluctuations are dominated by thermal
effects for a surprisingly large Pe numbers. Inspired by recent experiments, we
also study finite sedimentation in a horizontal planar slit. In our simulations
distinct lateral patterns emerge, in agreement with observations in the
experiments.


title: A calculation of the bulk viscosity in SU(3) gluodynamics

abstract:
  We perform a lattice Monte-Carlo calculation of the trace-anomaly two-point
function at finite temperature in the SU(3) gauge theory. We obtain the
long-distance properties of the correlator in the continuum limit and extract
the bulk viscosity zeta via a Kubo formula. Unlike the tensor correlator
relevant to the shear viscosity, the scalar correlator depends strongly on
temperature. If s is the entropy density, we find that zeta/s becomes rapidly
small at high T, zeta/s<0.15 at 1.65T_c and zeta/s<0.015 at 3.2T_c. However
zeta/s rises dramatically just above T_c, with 0.5<zeta/s<2.0 at 1.02T_c.


title: Weighted Sequences in Finite Cyclic Groups

abstract:
  Let $p>7$ be a prime, let $G=\Z/p\Z$, and let $S_1=\prod_{i=1}^p g_i$ and
$S_2=\prod_{i=1}^p h_i$ be two sequences with terms from $G$. Suppose that the
maximum multiplicity of a term from either $S_1$ or $S_2$ is at most
$\frac{2p+1}{5}$. Then we show that, for each $g\in G$, there exists a
permutation $\sigma$ of $1,2,..., p$ such that $g=\sum_{i=1}^{p}(g_i\cdot
h_{\sigma(i)})$. The question is related to a conjecture of A. Bialostocki
concerning weighted subsequence sums and the Erd\H{o}s-Ginzburg-Ziv Theorem.


title:
A Neutrino Mass Matrix with Vanishing $\mu$--$\mu$ and $\tau$--$\tau$
  Entries

abstract:
  We revisit our earlier proposal for the form of the neutrino mass matrix: a
two-zero ansatz wherein the CP-violating PMNS phase $\delta$ plays a
surprisingly important role. We review its observable consequences and show how
our ansatz follows from a softly-broken symmetry (muon number minus tau lepton
number) in a see-saw model with three Higgs doublets.


title:
Operational determination of multi-qubit entanglement classes via tuning
  of local operations

abstract:
  We present a physical setup with which it is possible to produce arbitrary
symmetric long-lived multiqubit entangled states in the internal ground levels
of photon emitters, including the paradigmatic GHZ and W states. In the case of
three emitters, where each tripartite entangled state belongs to one of two
well-defined entanglement classes, we prove a one-to-one correspondence between
well-defined sets of experimental parameters, i.e., locally tunable polarizer
orientations, and multiqubit entanglement classes inside the symmetric
subspace.


title:
Electronic correlations in graphite and carbon nanotubes from Auger
  spectroscopy

abstract:
  We have determined the screened on-site Coulomb repulsion in graphite and
single wall carbon nanotubes by measuring their Auger spectra and performing a
new theoretical analysis based on an extended Cini-Sawatzky approach where only
one fit parameter is employed. The experimental lineshape is very well
reproduced by the theory and this allows to determine the value of the screened
on-site repulsion between $2p$ states, which is found to be 2.1 eV in graphite
and 4.6 eV in nanotubes. The latter is robust by varying the nanotube radius
from 1 to 2 nm.


title:
Ganea and Whitehead definitions for the tangential
  Lusternik-Schnirelmann category of foliations

abstract:
  This work solves the problem of elaborating Ganea and Whitehead definitions
for the tangential category of a foliated manifold. We develop these two
notions in the category $\Tops$ of stratified spaces, that are topological
spaces $X$ endowed with a partition $\cF$ and compare them to a third invariant
defined by using open sets. More precisely, these definitions apply to an
element $(X,\cF)$ of $\Tops$ together with a class $\cA$ of subsets of $X$;
they are similar to invariants introduced by M. Clapp and D. Puppe.
  If $(X,\cF)\in\Tops$, we define a transverse subset as a subspace $A$ of $X$
such that the intersection $S\cap A$ is at most countable for any $S\in \cF$.
Then we define the Whitehead and Ganea LS-categories of the stratified space by
taking the infimum along the transverse subsets. When we have a closed
manifold, endowed with a $C^1$-foliation, the three previous definitions, with
$\cA$ the class of transverse subsets, coincide with the tangential category
and are homotopical invariants.


title: Continuous first order orbital order-disorder transition in Nd1-xCaxMnO3

abstract:
  The nature of the cooperative Jahn-Teller (JT) transition accompanied by
orbital order-disorder in Nd1-xCaxMnO3 has been studied by high temperature
(300 - 1200K) synchrotron and laboratory X-ray powder diffraction in the low
doping region (0<x<0.1). For very low doping a large temperature range of phase
coexistence associated with a first-order transition has been observed,
resembling a martensitic transformation. The transition appears continuous
because of a gradual evolution of the volume fractions of the phases over a
broad temperature interval. The first-order nature of the transition and the
phase coexistence is suppressed with increasing of doping.


title:
Comment on "A Lagrangian for DSR Particle and the Role of
  Noncommutativity"

abstract:
  In this work, we comment on two special points in the paper by S. Ghosh
[Phys. Rev. D 74, 084019 (2006)]. First of all, the Lagrangian presented by the
author does not describe the Magueijo- Smolin model of Doubly Special
Relativity since it is equivalent to the Lagrangian of the standard free
relativistic particle. We also show that the introduction of noncommutative
structures is not relevant to the problem of Lorentz covariance in Ghosh
formalism.


title: Single-electron quantum dot in Si/SiGe with integrated charge-sensing

abstract:
  Single-electron occupation is an essential component to measurement and
manipulation of spin in quantum dots, capabilities that are important for
quantum information processing. Si/SiGe is of interest for semiconductor spin
qubits, but single-electron quantum dots have not yet been achieved in this
system. We report the fabrication and measurement of a top-gated quantum dot
occupied by a single electron in a Si/SiGe heterostructure. Transport through
the quantum dot is directly correlated with charge-sensing from an integrated
quantum point contact, and this charge-sensing is used to confirm
single-electron occupancy in the quantum dot.


title: Linkages in Polytope Graphs

abstract:
  A graph is k-linked if any k disjoint vertex-pairs can be joined by k
disjoint paths. We improve a lower bound on the linkedness of polytopes
slightly, which results in exact values for the minimal linkedness of 7-, 10-
and 13-dimensional polytopes.
  We analyze in detail linkedness of polytopes on at most (6d+7)/5 vertices. In
that case, a sharp lower bound on minimal linkedness is derived, and examples
meeting this lower bound are constructed. These examples contain a class of
examples due to Gallivan.


title: A universal GRB photon energy-peak luminosity relation

abstract:
  The energetics and emission mechanism of GRBs are not well understood. Here
we demonstrate that the instantaneous peak flux or equivalent isotropic peak
luminosity, L_iso ergs s^-1, rather than the integrated fluence or equivalent
isotropic energy, E_iso ergs, underpins the known high-energy correlations.
Using new spectral/temporal parameters calculated for 101 bursts with redshifts
from BATSE, BeppoSAX, HETE-II and Swift we describe a parameter space which
characterises the apparently diverse properties of the prompt emission. We show
that a source frame characteristic-photon-energy/peak luminosity ratio, K_z,
can be constructed which is constant within a factor of 2 for all bursts
whatever their duration, spectrum, luminosity and the instrumentation used to
detect them. The new parameterization embodies the Amati relation but indicates
that some correlation between E_peak and E_iso follows as a direct mathematical
inference from the Band function and that a simple transformation of E_iso to
L_iso yields a universal high energy correlation for GRBs. The existence of K_z
indicates that the mechanism responsible for the prompt emission from all GRBs
is probably predominantly thermal.


title:
L1Packv2: A Mathematica package for minimizing an $\ell_1$-penalized
  functional

abstract:
  L1Packv2 is a Mathematica package that contains a number of algorithms that
can be used for the minimization of an $\ell_1$-penalized least squares
functional. The algorithms can handle a mix of penalized and unpenalized
variables. Several instructive examples are given. Also, an implementation that
yields an exact output whenever exact data are given is provided.


title:
Direct Numerical Simulation of a separated channel flow with a smooth
  profile

abstract:
  A direct numerical simulation (DNS) of a channel flow with one curved surface
was performed at moderate Reynolds number (Re_tau = 395 at the inlet). The
adverse pressure gradient was obtained by a wall curvature through a
mathematical mapping from physical coordinates to Cartesian ones. The code,
using spectral spanwise and normal discretization, combines the advantage of a
good accuracy with a fast integration procedure compared to standard numerical
procedures for complex geometries. The turbulent flow slightly separates on the
profile at the lower curved wall and is at the onset of separation at the
opposite flat wall. The thin separation bubble is characterized with a reversal
flow fraction. Intense vortices are generated near the separation line on the
lower wall but also at the upper wall. Turbulent normal stresses and kinetic
energy budget are investigated along the channel.


title: Can Terrestrial Planets Form in Hot-Jupiter Systems?

abstract:
  Models of terrestrial planet formation in the presence of a migrating giant
planet have challenged the notion that hot-Jupiter systems lack terrestrial
planets. We briefly review this issue and suggest that hot-Jupiter systems
should be prime targets for future observational missions designed to detect
Earth-sized and potentially habitable worlds.


title:
Regularization of Hele-Shaw flows, multiscaling expansions and the
  Painleve I equation

abstract:
  Critical processes of ideal integrable models of Hele-Shaw flows are
considered. A regularization method based on multiscaling expansions of
solutions of the KdV and Toda hierarchies characterized by string equations is
proposed. Examples are exhibited in which the tritronq'ee solution of the
Painleve-I equation turns out to provide the leading term of the regularization


title: Spitzer's View of Edge-on Spirals

abstract:
  Edge-on spiral galaxies offer a unique perspective on disks. One can
accurately determine the height distribution of stars and ISM and the
line-of-sight integration allows for the study of faint structures. The Spitzer
IRAC camera is an ideal instrument to study both the ISM and stellar structure
in nearby galaxies; two of its channels trace the old stellar disk with little
extinction and the 8 micron channel is dominated by the smallest dust grains
(Polycyclic Aromatic Hydrocarbons, PAHs). Dalcanton et al. (2004) probed the
link between the appearance of dust lanes and the disk stability. In a sample
of bulge-less disks they show how in massive disks the ISM collapses into the
characteristic thin dust lane. Less massive disks are gravitationally stable
and their dust morphology is fractured. The transition occurs at 120 km/s for
bulgeless disks. Here we report on our results of our Spitzer/IRAC survey of
nearby edge-on spirals and its first results on the NIR Tully-Fischer relation,
and ISM disk stability.


title:
Composite Strings in (2+1)-Dimensional Anisotropic Weakly-Coupled
  Yang-Mills Theory

abstract:
  The small-scale structure of a string connecting a pair of static sources is
explored for the weakly-coupled anisotropic SU(2) Yang-Mills theory in (2+1)
dimensions. A crucial ingredient in the formulation of the string Hamiltonian
is the phenomenon of color smearing of the string constituents. The
quark-anti-quark potential is determined. We close with some discussion of the
standard, fully Lorentz-invariant Yang-Mills theory.

categories: hep-th cond-mat.str-el hep-lat math-ph math.MP


title:
Superfluid Fermi-Fermi mixture: phase diagram, stability, and soliton
  formation

abstract:
  We study the phase diagram for a dilute Bardeen-Cooper-Schrieffer superfluid
Fermi-Fermi mixture (of distinct mass) at zero temperature using energy
densities for the superfluid fermions in one (1D), two (2D), and three (3D)
dimensions. We also derive the dynamical time-dependent nonlinear
Euler-Lagrange equation satisfied by the mixture in one dimension using this
energy density. We obtain the linear stability conditions for the mixture in
terms of fermion densities of the components and the interspecies Fermi-Fermi
interaction. In equilibrium there are two possibilities. The first is that of a
uniform mixture of the two components, the second is that of two pure phases of
two components without any overlap between them. In addition, a mixed and a
pure phase, impossible in 1D and 2D, can be created in 3D. We also obtain the
conditions under which the uniform mixture is stable from an energetic
consideration. The same conditions are obtained from a modulational instability
analysis of the dynamical equations in 1D. Finally, the 1D dynamical equations
for the system are solved numerically and by variational approximation (VA) to
study the bright solitons of the system for attractive interspecies Fermi-Fermi
interaction in 1D. The VA is found to yield good agreement to the numerical
result for the density profile and chemical potential of the bright solitons.
The bright solitons are demonstrated to be dynamically stable. The experimental
realization of these Fermi-Fermi bright solitons seems possible with present
setups.


title: The Brownian gyrator: a minimal heat engine on the nano-scale

abstract:
  A Brownian particle moving in the vicinity of a generic potential minimum
under the influence of dissipation and thermal noise from two different heat
baths is shown to act as a minimal heat engine, generating a systematic torque
onto the physical object at the origin of the potential and an opposite torque
onto the medium generating the dissipation.


title: Analysis of Proton Radiography Images of Shock Melted/Damaged Tin

abstract:
  Tin coupons were shock damaged/melted under identical conditions with a
diverging high explosive shock wave. Proton Radiography images and velocimetry
data from experiments with seven different tin coupons of varying thickness are
analyzed. Comparing experiments with identical samples allowed us to
distinguish between repeatable and random features. Shapes and velocities of
the main fragments are deterministic functions of the coupon thickness; random
differences exist only at a small scale. Velocities of the leading layer and of
the main fragment differ by the same value independently of coupon thicknesses,
which is likely related to the separation energy of metal layers.


title:
Disorder, Metal-Insulator crossover and Phase diagram in high-Tc
  cuprates

abstract:
  We have studied the influence of disorder induced by electron irradiation on
the normal state resistivities $\rho(T)$ of optimally and underdoped YBa2CuOx
single crystals, using pulsed magnetic fields up to 60T to completely restore
the normal state. We evidence that point defect disorder induces low T upturns
of rho(T) which saturate in some cases at low T in large applied fields as
would be expected for a Kondo-like magnetic response. Moreover the magnitude of
the upturns is related to the residual resistivity, that is to the
concentration of defects and/or their nanoscale morphology. These upturns are
found quantitatively identical to those reported in lower Tc cuprates, which
establishes the importance of disorder in these supposedly pure compounds. We
therefore propose a realistic phase diagram of the cuprates, including
disorder, in which the superconducting state might reach the antiferromagnetic
phase in the clean limit.


title:
Fast optical preparation, control and read-out of single quantum dot
  spin

abstract:
  We propose and demonstrate the sequential initialization, optical control,
and read-out of a single spin trapped in a semiconductor quantum dot. Hole spin
preparation is achieved through ionization of a resonantly excited
electron-hole pair. Optical control is observed as a coherent Rabi rotation
between the hole and charged exciton states, which is conditional on the
initial hole spin state. The spin-selective creation of the charged exciton
provides a photocurrent read-out of the hole spin state.


title: (Non)Commutative Hopf algebras of trees and (quasi)symmetric functions

abstract:
  The Connes-Kreimer Hopf algebra of rooted trees, its dual, and the Foissy
Hopf algebra of of planar rooted trees are related to each other and to the
well-known Hopf algebras of symmetric and quasi-symmetric functions via a pair
of commutative diagrams. We show how this point of view can simplify
computations in the Connes-Kreimer Hopf algebra and its dual, particularly for
combinatorial Dyson-Schwinger equations.


title: Masses for the Local Group and the Milky Way

abstract:
  We use the very large Millennium Simulation of the concordance $\Lambda$CDM
cosmogony to calibrate the bias and error distribution of Timing Argument
estimators of the masses of the Local Group and of the Milky Way. From a large
number of isolated spiral-spiral pairs similar to the Milky Way/Andromeda
system, we find the interquartile range of the ratio of timing mass to true
mass to be a factor of 1.8, while the 5% and 95% points of the distribution of
this ratio are separated by a factor of 5.7. Here we define true mass as the
sum of the ``virial'' masses $M_{200}$ of the two dominant galaxies. For
current best values of the distance and approach velocity of Andromeda this
leads to a median likelihood estimate of the true mass of the Local Group of
$5.27\times 10^{12}\msun$, or $\log M_{LG}/M_\odot = 12.72$, with an
interquartile range of $[12.58, 12.83]$ and a 5% to 95% range of $[12.26,
13.01]$. Thus a 95% lower confidence limit on the true mass of the Local Group
is $1.81\times 10^{12}\msun$. A timing estimate of the Milky Way's mass based
on the large recession velocity observed for the distant satellite Leo I works
equally well, although with larger systematic uncertainties. It gives an
estimated virial mass for the Milky Way of $2.43 \times 10^{12}\msun$ with a
95% lower confidence limit of $0.80 \times 10^{12}\msun$.


title: Additional Gradings in Khovanov Homology

abstract:
  The main goal of the present paper is to construct new invariants of knots
with additional structure by adding new gradings to the Khovanov complex. The
ideas given below work in the case of virtual knots, closed braids and some
other cases of knots with additional structure. The source of our additional
grading may be topological or combinatorial; it is axiomatised for many partial
cases. As a byproduct, this leads to a complex which in some cases coincides
(up to grading renormalisation) with the usual Khovanov complex and in some
other cases with the Lee-Rasmussen complex.
  The grading we are going to construct behaves well with respect to some
generalisations of the Khovanov homology, e.g., Frobenius extensions. These new
homology theories give sharper estimates for some knot characteristics, such as
minimal crossing number, atom genus, slice genus, etc.
  Our gradings generate a natural filtration on the usual Khovanov complex.
There exists a spectral sequence starting with our homology and converging to
the usual Khovanov homology.


title: Bayesian Online Changepoint Detection

abstract:
  Changepoints are abrupt variations in the generative parameters of a data
sequence. Online detection of changepoints is useful in modelling and
prediction of time series in application areas such as finance, biometrics, and
robotics. While frequentist methods have yielded online filtering and
prediction techniques, most Bayesian papers have focused on the retrospective
segmentation problem. Here we examine the case where the model parameters
before and after the changepoint are independent and we derive an online
algorithm for exact inference of the most recent changepoint. We compute the
probability distribution of the length of the current ``run,'' or time since
the last changepoint, using a simple message-passing algorithm. Our
implementation is highly modular so that the algorithm may be applied to a
variety of types of data. We illustrate this modularity by demonstrating the
algorithm on three different real-world data sets.


title: Current Algebra on the Torus

abstract:
  We derive the N-point one-loop correlation functions for the currents of an
arbitrary affine Kac-Moody algebra. The one-loop amplitudes, which are elliptic
functions defined on the torus Riemann surface, are specified by group
invariant tensors and certain constant tau-dependent functions. We compute the
elliptic functions via a generating function, and explicitly construct the
invariant tensor functions recursively in terms of Young tableaux. The lowest
tensors are related to the character formula of the representation of the
affine algebra. These general current algebra loop amplitudes provide a
building block for open twistor string theory, among other applications.


title: Combinatorial Hopf algebras and Towers of Algebras

abstract:
  Bergeron and Li have introduced a set of axioms which guarantee that the
Grothendieck groups of a tower of algebras $\bigoplus_{n\ge0}A_n$ can be
endowed with the structure of graded dual Hopf algebras. Hivert and Nzeutzhap,
and independently Lam and Shimozono constructed dual graded graphs from
primitive elements in Hopf algebras. In this paper we apply the composition of
these constructions to towers of algebras. We show that if a tower
$\bigoplus_{n\ge0}A_n$ gives rise to graded dual Hopf algebras then we must
have $\dim(A_n)=r^nn!$ where $r = \dim(A_1)$.