title:
The characteristic polynomial on compact groups with Haar measure : some
  equalities in law

abstract:
  This note presents some equalities in law for $Z_N:=\det(\Id-G)$, where $G$
is an element of a subgroup of the set of unitary matrices of size $N$, endowed
with its unique probability Haar measure. Indeed, under some general
conditions, $Z_N$ can be decomposed as a product of independent random
variables, whose laws are explicitly known. Our results can be obtained in two
ways : either by a recursive decomposition of the Haar measure or by previous
results by Killip and Nenciu on orthogonal polynomials with respect to some
measure on the unit circle. This latter method leads naturally to a study of
determinants of a class of principal submatrices.


title:
Size Effects in the Magnetoresistance of Graphite: Absence of
  Magnetoresistance in Micrometer size Samples

abstract:
  We present a study of the magnetoresistance of highly oriented pyrolytic
graphite (HOPG) as a function of the sample size. Our results show
unequivocally that the magnetoresistance reduces with the sample size even for
samples of hundreds of micrometers size. This sample size effect is due the
large mean free path and Fermi wavelength of carriers in graphite and may
explain the observed practically absence of magnetoresistance in micrometer
confined small graphene samples where quantum effects should be at hand. These
were not taken into account in the literature yet and ask for a revision of
experimental and theoretical work on graphite.


title: Jet lag effect and leading hadron production

abstract:
  We propose a solution for the long standing puzzle of a too steeply falling
fragmentation function for a quark fragmenting into a pion, calculated by
Berger [1] in the Born approximation. Contrary to the simple anticipation that
gluon resummation worsens the problem, we find good agreement with data. Higher
quark Fock states slow down the quark, an effect which we call jet lag. It can
be also expressed in terms of vacuum energy loss. As a result, the space-time
development of the jet shrinks and the $z$-dependence becomes flatter than in
the Born approximation. The space-time pattern is also of great importance for
in-medium hadronization.


title: N-Body Simulations on GPUs

abstract:
  Commercial graphics processors (GPUs) have high compute capacity at very low
cost, which makes them attractive for general purpose scientific computing. In
this paper we show how graphics processors can be used for N-body simulations
to obtain improvements in performance over current generation CPUs. We have
developed a highly optimized algorithm for performing the O(N^2) force
calculations that constitute the major part of stellar and molecular dynamics
simulations. In some of the calculations, we achieve sustained performance of
nearly 100 GFlops on an ATI X1900XTX. The performance on GPUs is comparable to
specialized processors such as GRAPE-6A and MDGRAPE-3, but at a fraction of the
cost. Furthermore, the wide availability of GPUs has significant implications
for cluster computing and distributed computing efforts like Folding@Home.


title:
Pump-probe polarized transient hole burning (PTHB) dynamics of hydrated
  electron revisited

abstract:
  Femtosecond PTHB spectroscopy was expected to demonstrate the existence of
distinct s-p absorption subbands originating from the three nondegenerate
p-like excited states of hydrated electron in anisotropic solvation cavity. Yet
no conclusive experimental evidence either for this subband structure or the
reorientation of the cavity on the picosecond time scale has been obtained. We
demonstrate that rapid reorientation of s-p transition dipole moments in
response to small scale motion of water molecules is the likely culprit. The
polarized bleach is shown to be too small and too short lived to be observed
reliably on the sub-picosecond time scale.


title:
Carbon Detonation and Shock-Triggered Helium Burning in Neutron Star
  Superbursts

abstract:
  The strong degeneracy of the 12C ignition layer on an accreting neutron star
results in a hydrodynamic thermonuclear runaway, in which the nuclear heating
time becomes shorter than the local dynamical time. We model the resulting
combustion wave during these superbursts as an upward propagating detonation.
We solve the reactive fluid flow and show that the detonation propagates
through the deepest layers of fuel and drives a shock wave that steepens as it
travels upward into lower density material. The shock is sufficiently strong
upon reaching the freshly accreted H/He layer that it triggers unstable 4He
burning if the superburst occurs during the latter half of the regular Type I
bursting cycle; this is likely the origin of the bright Type I precursor bursts
observed at the onset of superbursts. The cooling of the outermost shock-heated
layers produces a bright, ~0.1s, flash that precedes the Type I burst by a few
seconds; this may be the origin of the spike seen at the burst onset in 4U
1820-30 and 4U 1636-54, the only two bursts observed with RXTE at high time
resolution. The dominant products of the 12C detonation are 28Si, 32S, and
36Ar. Gupta et al. showed that a crust composed of such intermediate mass
elements has a larger heat flux than one composed of iron-peak elements and
helps bring the superburst ignition depth into better agreement with values
inferred from observations.


title:
Self-similar shear-thickening behavior in CTAB/NaSal surfactant
  solutions

abstract:
  The effect of salt concentration Cs on the critical shear rate required for
the onset of shear thickening and apparent relaxation time of the
shear-thickened phase, has been investigated systematically for dilute
CTAB/NaSal solutions. Experimental data suggest a self-similar behavior of the
critical shear rate and relaxation time as functions of Cs. Specifically, the
former ~ Cs^(-6) whereas the latter ~ Cs^(6) such that an effective Weissenberg
number for the onset of the shear thickened phase is only weakly dependent on
Cs. A procedure has been developed to collapse the apparent shear viscosity
versus shear rate data obtained for various values of Cs into a single master
curve. The effect of Cs on the elastic modulus and mesh size of the
shear-induced gel phase for different surfactant concentrations is discussed.
Experiments performed using different flow cells (Couette and cone-and-plate)
show that the critical shear rate, relaxation time and the maximum viscosity
attained are geometry-independent. The elastic modulus of the gel phase
inferred indirectly by employing simplified hydrodynamic instability analysis
of a sheared gel-fluid interface is in qualitative agreement with that
predicted for an entangled phase of living polymers. A qualitative mechanism
that combines the effect of Cs on average micelle length and Debye parameter
with shear-induced configurational changes of rod-like micelles is proposed to
rationalize the self-similarity of SIS formation.


title: Growing Matter

abstract:
  We investigate quintessence cosmologies with a matter component consisting of
particles with an increasing mass. While negligible in early cosmology, the
appearance of a growing matter component has stopped the evolution of the
cosmon field at a redshift around six. In turn, this has triggered the
accelerated expansion of the Universe. We propose to associate growing matter
with neutrinos. Then the presently observed dark energy density and its
equation of state are determined by the neutrino mass.


title: Double Chargino Production in $e^{-}e^{-}$ scattering

abstract:
  We point out the production of the charginos and neutralinos in
electron-electron process in several supersymmetric models, in order to show
that the International Linear Collider can discover double charged charginos if
these particles really exist in nature.


title: Dielectric microscopy with submillimeter resolution

abstract:
  In analogy with optical near-field scanning methods, we use tapered
dielectric waveguides as probes for a millimeter wave vector network analyzer.
By scanning thin samples between two such probes we are able to map the
spatially varying dielectric properties of materials with sub-wavelength
resolution; using a 150 GHz probe in transmision mode we see spatial resolution
of around 500 microns. We have applied this method to a variety of highly
heterogeneous materials. Here we show dielectric maps of granite and oil shale.


title:
Fitting analysis provides further evidence for eradication of hiv/aids
  infection under combined liposome drug delivery treatment

abstract:
  It is now evident that the commonly accepted strategy for treatment of
HIV/AIDS by highly active antiretroviral therapy (HAART) will not lead to
eradication of HIV in a reasonable time. This is straightforward from the
typical exponential viral load decay upon treatment revealing initial
considerable but incomplete reduction of plasma HIV RNA with subsequent low
level HIV persistence even in patients on effective antiretroviral therapy.
Here we show that the viral load follows a simple zero trend linear regression
line under different treatment approach recently proposed by us. This
unambiguously indicates a whole body HIV eradication in reasonable time.


title:
A 12um ISOCAM Survey of the ESO-Sculptor Field: Data Reduction and
  Analysis

abstract:
  We present a detailed reduction of a mid-infrared 12um (LW10 filter) ISOCAM
open time observation performed on the ESO-Sculptor Survey field (Arnouts et
al. 1997). A complete catalogue of 142 sources (120 galaxies and 22 stars),
detected with high significance (equivalent to 5sigma), is presented above an
integrated flux density of 0.24mJy. Star/galaxy separation is performed by a
detailed study of colour-colour diagrams. The catalogue is complete to 1mJy and
below this flux density the incompleteness is corrected using two independent
methods. The first method uses stars and the second uses optical counterparts
of the ISOCAM galaxies; these methods yield consistent results. We also apply
an empirical flux density calibration using stars in the field. For each star,
the 12um flux density is derived by fitting optical colours from a multi-band
chi^2 to stellar templates (BaSel-2.0) and using empirical optical-IR
colour-colour relations. This article is a companion analysis to
Rocca-Volmerange 2007 et al. where the 12um faint galaxy counts are presented
and analysed by galaxy type with the evolutionary code PEGASE.3.


title: Network synchronization: Spectral versus statistical properties

abstract:
  We consider synchronization of weighted networks, possibly with asymmetrical
connections. We show that the synchronizability of the networks cannot be
directly inferred from their statistical properties. Small local changes in the
network structure can sensitively affect the eigenvalues relevant for
synchronization, while the gross statistical network properties remain
essentially unchanged. Consequently, commonly used statistical properties,
including the degree distribution, degree homogeneity, average degree, average
distance, degree correlation, and clustering coefficient, can fail to
characterize the synchronizability of networks.


title:
Potential for the slow-roll inflation, mass scale hierarchy and Dark
  Energy from the Type IIA supergravity

abstract:
  The magnetic fluxbrane solution with a strongly warped throat is studied in
the Type IIA supergravity theory with co-dimension one local source which
surves as $Z_{2}$-symmetric UV boundary of the throat. Overall volume of extra
space is stabilized since introduction of the local source breaks the no-scale
structure of the theory and evades the no-go theorem. Radion field is defined
as the position of UV boundary "moved" from its stable value fixed by the
anisotropic Israel junction conditions. Analytical expression for the radion
effective potential is received. Potential decreases exponentially (exponent is
equal to 0,21 in Planck units) in the slow-roll region and apparently meets
other demands of the early inflation. Reissner-Nordstrom type deformation of
the elementary fluxbrane solution permits to construct the IR end of the throat
and results in tiny positive non-zero value of the radion potential in its
extremal point seen today as Dark Energy $\rho_{D.E.}$. Expressions for the
mass scale hierarchy and for the "acceleration hierarchy" received in the paper
give the physically interesting relation between two hierarchies: $\rho_{D.E.}
\sim G_{N}^{2}m^{8}$.


title: Extreme values for Benedicks-Carleson quadratic maps

abstract:
  We consider the quadratic family of maps given by $f_{a}(x)=1-a x^2$ with
$x\in [-1,1]$, where $a$ is a Benedicks-Carleson parameter. For each of these
chaotic dynamical systems we study the extreme value distribution of the
stationary stochastic processes $X_0,X_1,...$, given by $X_{n}=f_a^n$, for
every integer $n\geq0$, where each random variable $X_n$ is distributed
according to the unique absolutely continuous, invariant probability of $f_a$.
Using techniques developed by Benedicks and Carleson, we show that the limiting
distribution of $M_n=\max\{X_0,...,X_{n-1}\}$ is the same as that which would
apply if the sequence $X_0,X_1,...$ was independent and identically
distributed. This result allows us to conclude that the asymptotic distribution
of $M_n$ is of Type III (Weibull).


title:
Efficient vibrational state coupling in an optical tilted-washboard
  potential via multiple spatial translations and application to pulse echo

abstract:
  We measure the application of simple and compound pulses consisting of
time-dependent spatial translations to coupling vibrational states of ultracold
85Rb atoms in a far-detuned 1D optical lattice. The lattice wells are so
shallow as to support only two bound states, and we prepare the atoms in the
ground state. The lattice is oriented vertically, leading to a tilted-washboard
potential analogous to those encountered in condensed-matter systems.
Experimentally, we find that a square pulse consisting of lattice displacements
and a delay is more efficient than single-step and Gaussian pulses. This is
described as an example of coherent control. It is striking that contrary to
the intuition that soft pulses minimize loss, the Gaussian pulse is
outperformed by the square pulse. Numerical calculations are in strong
agreement with our experimental results and show the superiority of the square
pulse to the single-step pulse for all lattice depths and to the Gaussian pulse
for lattice depths greater than 7 lattice recoil energies. We also compare the
effectiveness of these pulses for reviving oscillations of atoms in vibrational
superposition states using the pulse-echo technique. We find that the square
and Gaussian pulses result in higher echo amplitudes than the single-step
pulse. These improved echo pulses allow us to probe coherence at longer times
than in the past, measuring a plateau which has yet to be explained. In
addition, we show numerically that the vibrational state coupling due to such
lattice manipulations is more efficient in shallow lattices than in deep
lattices.


title: Tau-function of discrete isomonodromy transformations and probability

abstract:
  We introduce the tau-function of a rational d-connection and its isomonodromy
transformations. We show that in a continuous limit our tau-function agrees
with the Jimbo-Miwa-Ueno tau-function, compute the tau-function for the
isomonodromy transformations leading to difference Painleve V and difference
Painleve VI equations, and prove that the gap probability for a wide class of
discrete random matrix type models can be viewed as the tau-function for an
associated d-connection.


title:
A review of wildland fire spread modelling, 1990-present, 1: Physical
  and quasi-physical models

abstract:
  In recent years, advances in computational power and spatial data analysis
(GIS, remote sensing, etc) have led to an increase in attempts to model the
spread and behaviour of wildland fires across the landscape. This series of
review papers endeavours to critically and comprehensively review all types of
surface fire spread models developed since 1990. This paper reviews models of a
physical or quasi-physical nature. These models are based on the fundamental
chemistry and/or physics of combustion and fire spread. Other papers in the
series review models of an empirical or quasi-empirical nature, and
mathematical analogues and simulation models. Many models are extensions or
refinements of models developed before 1990. Where this is the case, these
models are also discussed but much less comprehensively.


title:
Stochastic Lorentz forces on a point charge moving near the conducting
  plate

abstract:
  The influence of quantized electromagnetic fields on a nonrelativistic
charged particle moving near a conducting plate is studied. We give a
field-theoretic derivation of the nonlinear, non-Markovian Langevin equation of
the particle by the method of Feynman-Vernon influence functional. This
stochastic approach incorporates not only the stochastic noise manifested from
electromagnetic vacuum fluctuations, but also dissipation backreaction on a
charge in the form of the retarded Lorentz forces. Since the imposition of the
boundary is expected to anisotropically modify the effects of the fields on the
evolution of the particle, we consider the motion of a charge undergoing
small-amplitude oscillations in the direction either parallel or normal to the
plane boundary. Under the dipole approximation for nonrelativistic motion,
velocity fluctuations of the charge are found to grow linearly with time in the
early stage of the evolution at the rather different rate, revealing strong
anisotropic behavior. They are then asymptotically saturated as a result of the
fluctuation-dissipation relation, and the same saturated value is found for the
motion in both directions. The observational consequences are discussed. plane
boundary. Velocity fluctuations of the charge are found to grow linearly with
time in the early stage of the evolution at the rate given by the relaxation
constant, which turns out to be smaller in the parallel case than in the
perpendicular one in a similar configuration. Then, they are asymptotically
saturated as a result of the fluctuation-dissipation relation. For the
electron, the same saturated value is obtained for motion in both directions,
and is mainly determined by its oscillatory motion. Possible observational
consequences are discussed.


title: On the Performance of Joint Fingerprint Embedding and Decryption Scheme

abstract:
  Till now, few work has been done to analyze the performances of joint
fingerprint embedding and decryption schemes. In this paper, the security of
the joint fingerprint embedding and decryption scheme proposed by Kundur et al.
is analyzed and improved. The analyses include the security against
unauthorized customer, the security against authorized customer, the
relationship between security and robustness, the relationship between
secu-rity and imperceptibility and the perceptual security. Based these
analyses, some means are proposed to strengthen the system, such as multi-key
encryp-tion and DC coefficient encryption. The method can be used to analyze
other JFD schemes. It is expected to provide valuable information to design JFD
schemes.


title: Exact solution of the Faddeev-Volkov model

abstract:
  The Faddeev-Volkov model is an Ising-type lattice model with positive
Boltzmann weights where the spin variables take continuous values on the real
line. It serves as a lattice analog of the sinh-Gordon and Liouville models and
intimately connected with the modular double of the quantum group U_q(sl_2).
The free energy of the model is exactly calculated in the thermodynamic limit.
In the quasi-classical limit c->infinity the model describes quantum
fluctuations of discrete conformal transformations connected with the
Thurston's discrete analogue of the Riemann mappings theorem. In the
strongly-coupled limit c->1 the model turns into a discrete version of the D=2
Zamolodchikov's ``fishing-net'' model.

categories: cond-mat.stat-mech hep-th math-ph math.MP


title: Index Theorem in Finite Noncommutative Geometry

abstract:
  Index theorem is formulated in noncommutative geometry with finite degrees of
freedom by using Ginsparg-Wilson relation. It is extended to the case where the
gauge symmetry is spontaneously broken. Dynamical analysis about topological
aspects in gauge theory is also shown.


title:
Revisiting the QCD corrections to the R-parity violating processes
  $p\bar{p}/pp \to e\mu+X$

abstract:
  We present the theoretical predictions up to QCD NLO for the cross section of
high-mass electron-muon pair production at the Tevatron and the LHC,
considering only the dominant contributions from the third-generation
sneutrino. The dependence of the renormalization and factorization scales on
the total cross section, and the effects on the K-factor due to the uncertainty
of parton distribution function(PDF) have been carefully investigated. By
considering soft-gluon resummation effects to all order in $\alpha_s$ of
leading logarithm, we present the transverse momentum distributions of the
final $e\mu$ pair.


title: Does a black hole rotate in Chern-Simons modified gravity?

abstract:
  Rotating black hole solutions in the (3+1)-dimensional Chern-Simons modified
gravity theory are discussed by taking account of perturbation around the
Schwarzschild solution. The zenith-angle dependence of a metric function
related to the frame-dragging effect is determined from a constraint equation
independently of a choice of the embedding coordinate. We find that at least
within the framework of the first-order perturbation method, the black hole
cannot rotate for finite black hole mass if the embedding coordinate is taken
to be a timelike vector. However, the rotation can be permitted in the limit of
$M/r \to 0$ (where $M$ is the black hole mass and $r$ is the radius). For a
spacelike vector, the rotation can also be permitted for any value of the black
hole mass.


title: Strong Uniqueness of the Ricci Flow

abstract:
  In this paper, we derive some local a priori estimates for Ricci flow. This
gives rise to some strong uniqueness theorems. As a corollary, let $g(t)$ be a
smooth complete solution to the Ricci flow on $\mathbb{R}^{3}$, with the
canonical Euclidean metric $E$ as initial data, then $g(t)$ is trivial, i.e.
$g(t)\equiv E$.


title: Configurations of Extremal Even Unimodular Lattices

abstract:
  We extend the results of Ozeki on the configurations of extremal even
unimodular lattices. Specifically, we show that if L is such a lattice of rank
56, 72, or 96, then L is generated by its minimal-norm vectors.


title:
Perturbative spectrum of a Yukawa-Higgs model with Ginsparg-Wilson
  fermions

abstract:
  A Yukawa-Higgs model with Ginsparg-Wilson (GW) fermions, proposed recently by
Bhattacharya, Martin and Poppitz as a possible lattice formulation of chiral
gauge theories, is studied. A simple argument shows that the gauge boson always
acquires mass by the St\"uckelberg (or, in a broad sense, Higgs) mechanism,
regardless of strength of interactions. The gauge symmetry is spontaneously
broken. When the gauge coupling constant is small, the physical spectrum of the
model consists of massless fermions, massive fermions and \emph{massive} vector
bosons.


title:
VLA H53alpha observations of the central region of the Super Star
  Cluster Galaxy NGC 5253

abstract:
  We present observations in the H53alpha line and radio continuum at 43 GHz
carried out with the VLA in the D array (2'' angular resolution) toward the
starburst galaxy NGC 5253. VLA archival data have been reprocessed to produce a
uniform set of 2, 1.3 and 0.7 cm high angular (0.''2 X 0.''1) radio continuum
images. The RRL H53alpha, a previously reported measurement of the H92alpha RRL
flux density and the reprocessed high angular resolution radio continuum flux
densities have been modeled using a collection of HII regions. Based on the
models, the ionized gas in the nuclear source has an electron density of ~6 X
10^4 cm^-3 and an volume filling factor of 0.05. A Lyman continuum photon
production rate of 2 X 10^52 s^-1 is necessary to sustain the ionization in the
nuclear region. The number of required O7 stars in the central 1.5 pc of the
supernebula is ~ 2000. The H53alpha velocity gradient 10 km s^-1 arcsec^-1)
implies a dynamical mass of ~3X10^5 Msun; this mass suggests the supernebula is
confined by gravity.


title: The optical spectrum of R Coronae Borealis close to 2003 decline

abstract:
  Two sets of high-resolution spectra of R CrB obtained during the 2003 light
decline are described. The first set was obtained on the descending branch of
the light curve when V ~12.0 and the second one in the recovery phase with V
~7.5. The usual sharp and broad emissions are described and the lines radial
velocities measured. C_2 Swan system (0,0) band was found to be in emission for
the first set. The other C_2 bands were in absorption. Few CN red system (5,1)
band rotational lines and low excitation FeI lines were in absorption. A table
with measured radial velocities of various spectral features is presented.


title: Estimates of Gromov's box distance

abstract:
  In 1999, M. Gromov introduced the box distance function $\sikaku$ on the
space of all mm-spaces. In this paper, by using the method of T. H. Colding
(cf. \cite[Lemma 5.10]{Colding}), we estimate
$\sikaku(\mathbb{S}^n,\mathbb{S}^m)$ and $\sikaku (\mathbb{C}P^n,
  \mathbb{C}P^m)$, where $\mathbb{S}^n$ is the $n$-dimensional unit sphere in
$\mathbb{R}^{n+1}$ and $\mathbb{C}P^n$ is the $n$-dimensional complex
projective space equipped with the Fubini-Study metric. In paticular, we give
the complete answer to an Exercise of Gromov's Green book (cf. \cite[Section
$3{1/2}.18$]{gromov}). We also estimate $\sikaku \big(SO(n), SO(m)\big)$ from
below, where SO(n) is the special orthogonal group.


title: Stark units and main conjectures for totally real fields

abstract:
  Main theorem of [Buyukboduk, arXiv:0706.0377v1] suggests that it should be
possible to lift the Kolyvagin systems of Stark units constructed in
[Buyukboduk, arXiv:math/0703426v1] to a Kolyvagin system over the cyclotomic
Iwasawa algebra. This is what we prove in this paper. This construction gives
the first example towards a more systematic study of Kolyvagin system theory
over an Iwasawa algebra when the core Selmer rank is greater than one. As a
result of this construction, we reduce the main conjectures of Iwasawa theory
for totally real fields to a statement of local Iwasawa theory. This statement,
however, turns out to be interesting in its own right as it suggests a relation
between solutions to $p$-adic and complex Stark conjectures.


title:
Quantum and thermal fluctuations in a two-dimensional correlated band
  ferromagnet -- Goldstone-mode preserving investigation with self-energy and
  vertex corrections

abstract:
  Ferromagnetism in the t-t' Hubbard model is investigated on a square lattice.
Correlation effects in the form of self-energy and vertex corrections are
systematically incorporated within a spin-rotationally-symmetric scheme which
explicitly preserves the Goldstone mode and is therefore in accord with the
Mermin-Wagner theorem. Interplay of band dispersion and correlation effects on
ferromagnetic-state stability are highlighted with respect to both long- and
short-wavelength fluctuations, which are shown to have substantially different
behaviour. Our approach provides a novel understanding of the enhancement of
ferromagnetism near van Hove filling for t'~0.5 in terms of strongly suppressed
saddle-point contribution to the destabilizing exchange part of spin stiffness.
Finite-temperature electron spin dynamics is investigated directly in terms of
spectral-weight transfer across the Fermi energy due to electron-magnon
coupling. Relevant in the context of recent magnetization measurements on
ultrathin films, the role of strong thermal spin fluctuations in low dimensions
is highlighted, in the anisotropy-stabilized ordered state, by determining the
thermal decay of magnetization and T_c within a renormalized spin-fluctuation
theory.


title: Can Chandra resolve the remaining cosmic X-ray background?

abstract:
  The deepest extragalactic X-ray observation, the 2 Ms Chandra Deep Field
North (CDF-N), resolves ~80% of the total extragalactic cosmic X-ray background
(CXB) in the 1-2 keV band. Recent work has shown that 70% of the remaining CXB
flux is associated with sources detected by the Hubble Space Telescope (HST).
This paper uses the existing CDF-N data to constrain the X-ray flux
distribution of these X-ray undetected HST sources, by comparing the number of
0.5-2 keV X-ray counts at the HST positions to those expected for model flux
distributions. In the simple case where all the undetected HST X-ray sources
have the same 0.5-2 keV flux, the data are best fit by 1.5-3 counts per source
in 2 Ms, compared to a detection limit (at 10% completeness) of 9 counts.
Assuming a more realistic power-law logN-logS distribution [N(>S) S^-alpha],
the data favor a relatively steep flux distribution, with alpha=1.1^+0.5_-0.3
(limits are 99% confidence). This slope is very similar to that previously
found for faint normal and starburst galaxies in the CDF-N. These results
suggest deeper Chandra observations will detect a new population of faint X-ray
sources, but extremely deep exposures are needed to resolve the remainder of
the soft CXB. In the most optimistic scenario, when the HST sources have the
flattest allowed flux distribution and all the sources without HST counterparts
are detected, observations 5 times more sensitive than the existing ones would
resolve at most ~60% of the remaining soft CXB.


title:
Flexible-to-semiflexible chain crossover on the pressure-area isotherm
  of lipid bilayer

abstract:
  We found theoretically that competition between ~Kq^4 and ~Qq^2 terms in the
Fourier transformed conformational energy of a single lipid chain, in
combination with inter-chain entropic repulsion in the hydrophobic part of the
lipid (bi)layer, may cause a crossover on the bilayer pressure-area isotherm
P(A)~(A-A_0)^{-n}. The crossover manifests itself in the transition from n=5/3
to n=3. Our microscopic model represents a single lipid molecule as a worm-like
chain with finite irreducible cross-section area A_0, flexural rigidity K and
stretching modulus Q in a parabolic potential with self-consistent curvature
B(A) formed by entropic interactions between hydrocarbon chains in the lipid
layer. The crossover area per lipid A* obeys relation Q^2/(KB(A*))~1 . We
predict a peculiar possibility to deduce effective elastic moduli K and Q of
the individual hydrocarbon chain from the analysis of the isotherm possessing
such crossover. Also calculated is crossover-related behavior of the area
compressibility modulus K_a, equilibrium area per lipid A_t, and chain order
parameter S.


title:
On the well-posedness of the Cauchy problem for the generalized
  Korteweg-de Vries-Burgers equation

abstract:
  Considered is the generalized Korteweg-de Vries-Burgers equation $$
u_{t}+u_{xxx}+uu_{x}+|D_{x}|^{2\alpha}u=0,\quad t\in \mathbb{R}^{+}, x\in
\mathbb{R}, $$ with $0\leq \alpha\le 1$. We prove a sharp results on the
associated Cauchy problem in the Sobolev space $ {H}^s(\mathbb{R})$. For
$s>-\min\{\frac {3+2\alpha}4, 1\}$ we give the well-posedness of solutions of
the Cauchy problem, while for $\frac 12\le\alpha\le 1$ and for $s<-\min\{\frac
{3+2\alpha}4, 1\}$ we show some ill-posedness issues.


title: On $(2k)$-Minimal Submanifolds

abstract:
  Recall that a submanifold of a Riemannian manifold is said to be minimal if
its mean curvature is zero. It is classical that minimal submanifolds are the
critical points of the volume function. In this paper, we examine the critical
points of the total $(2k)$-th Gauss-Bonnet curvature function, called
$(2k)$-minimal submanifolds. We prove that they are characterized by the
vanishing of a higher mean curvature, namely the $(2k+1)$-Gauss-Bonnet
curvature. Furthermore, we show that several properties of usual minimal
submanifolds can be naturally generalized to $(2k)$-minimal submanifolds.


title:
Addendum: "On the nature of the phase transition in the itinerant
  helimagnet MnSi", arXiv:cond-mat/0702460v1 [cond-mat.str-el]

abstract:
  New high resolution data for heat capacity, heat capacity under applied
magnetic fields and resistivity of high quality single crystal of MnSi are
reported. Striking mirror symmetry between temperature derivative of
resistivity and thermal expansion coefficient of MnSi is displayed. Close
similarity between variation of the heat capacity and the temperature
derivative of resistivity through the phase transition is observed. It is shown
that the heat capacity and thermal expansion coefficient of the helical phase
are not influenced by moderate magnetic field.


title:
Direct-current control of radiation-induced differential
  magnetoresistance oscillations in two-dimensional electron systems

abstract:
  Magnetoresistance oscillations in two-dimensional electron systems driven
simultaneously by a strong direct current and a microwave irradiation, are
analyzed within a unified microscopic scheme treating both excitations on an
equal footing. The microwave-induced resistance oscillations are described by a
parameter $\epsilon_\omega$ proportional to the radiation frequency, while the
dc-induced resistance oscillations are governed by a parameter $\epsilon_j$
proportional to the current density. In the presence of both a microwave
radiation and a strong dc, the combined parameter $\epsilon_\omega+\epsilon_j$
is shown to control the main resistance oscillations, in agreement with the
recent measurement [Zhang {\it et al.} Phys. Rev. Lett. {\bf 98}, 106804
(2007)]


title:
Channeling Effect and Improvement of the Efficiency of Charged Particle
  Registration with Crystal Scintillators

abstract:
  The importance is emphasized of taking into account the channeling along the
low index crystallographic axes and planes of a part of low-energy (1-10 keV)
recoil ions in measurements of their parameters with crystal scintillators of
the type of NaI(Tl) etc. Because the nucleus stopping power in channels is low
as compared with electronic stopping power, the light yield of the scintillator
must be, accordingly, higher in the given case than that for ions having higher
energy (tens keV and more), which lose most part of their energy via nuclear
collisions outside channels. Hence, in particular, it follows that the DAMA/NaI
observations in Gran Sasso of the annual modulation of the signal frequency in
a narrow range of scintillations with an amplitude of 2-6 keV electron
equivalent may be due to incidence onto the Earth of exceedingly massive
particles (of the type of Planckian objects) from elongated Earth-crossing
heliocentric orbits at a velocity of 30-50 km/s. In NaI(Tl), these particles
create the iodine recoil ions with just the energy of 2-6 keV.


title: The frequency separations of stellar p-modes

abstract:
  Aims. The purpose of this work is to investigate a new frequency separation
of stellar p-modes and its characteristics. Methods. Frequency separations are
deduced from the asymptotic formula of stellar p-modes. Then, using the
theoretical adiabatic frequencies of stellar model, we compute the frequency
separations. Results. A new separation $\sigma_{l-1 l+1}(n)$, which is similar
to the scaled small separation $d_{l l+2}(n)/(2l+3)$, is obtained from the
asymptotic formula of stellar p-modes. The separations $\sigma_{l-1 l+1}(n)$
and $d_{l l+2}(n)/(2l+3)$ have the same order. And like the small separation,
$\sigma_{l-1 l+1}(n)$ is mainly sensitive to the conditions in the stellar
core. However, with the decrease of the central hydrogen abundance of stars,
the $\sigma_{02}$ and $\sigma_{13}$ more and more deviate from the scaled small
separation. This characteristic could be used to extract the information on the
central hydrogen abundance of stars.


title: The nature of the fluorescent iron line in V 1486 Ori

abstract:
  The fluorescent 6.4 keV iron line provides information on cool material in
the vicinity of hard X-ray sources as well as on the characteristics of the
X-ray sources themselves. First discovered in the X-ray spectra of the flaring
Sun, X-ray binaries and active galactic nuclei (AGN), the fluorescent line was
also observed in a number of stellar X-ray sources. The young stellar object
(YSO) V1486 Ori was observed in the framework of the Chandra Ultra Deep Project
(COUP) as the source COUP 331. We investigate its spectrum, with emphasis on
the strength and time variability of the fluorescent iron K-alpha line, derive
and analyze the light curve of COUP 331 and proceed with a time-resolved
spectral analysis of the observation. The light curve of V 1486 Ori shows two
major flares, the first one lasting for (approx) 20 ks with a peak X-ray
luminosity of 2.6*10^{32} erg/s (dereddened in the 1-10 keV band) and the
second one -- only partially observed -- for >60 ks with an average X-ray
luminosity of 2.4*10^{31} erg/s (dereddened). The spectrum of the first flare
is very well described by an absorbed thermal model at high temperature, with a
pronounced 6.7 keV iron line complex, but without any fluorescent K-alpha line.
The X-ray spectrum of the second flare is characterized by even higher
temperatures (>= 10 keV) without any detectable 6.7 keV Fe XXV feature, but
with a very strong fluorescent iron K-alpha line appearing predominantly in the
20 ks rise phase of the flare. Preliminary model calculations indicate that
photoionization is unlikely to account for the entire fluorescent emission
during the rise phase.


title:
Bayesian analysis of joint strong gravitational lensing and dynamic
  galactic mass in SLACS: evidence of line-of-sight contamination

abstract:
  We readdress the calculation of the mass of early-type galaxies using strong
gravitational lensing and stellar dynamics. Our sample comprises 27 galaxies in
the Sloan Lens ACS (SLACS) Survey. Comparing the mass estimates from these two
independent methods in a Bayesian framework, we find evidence of significant
line-of-sight mass contamination. Assuming a power-law mass distribution, the
best fit density profile is given by $\rho \propto r^{-1.69\pm0.05}$. We show
that neglecting the line-of-sight mass contamination produces an overestimate
of the mass attributed to the lens-galaxy by the lensing method, which
introduces a bias in favor of a SIS profile when using the joint lensing and
dynamic analysis to determine the slope of the density profile. We suggest that
the line-of-sight contamination could also be important for other astrophysical
and cosmological uses of joint lensing and dynamical measurements.


title:
An Improved Process for Fabricating High-Mobility Organic Molecular
  Crystal Field-Effect Transistors

abstract:
  In this paper we present an improved process for producing elastomer
transistor stamps and high-mobility organic field-effect transistors (FETs)
based on semiconducting acene molecular crystals. In particular, we have
removed the need to use a silanized Si wafer for curing the stamps and to
handle a fragile micron-thickness polydimethylsiloxane (PDMS) insulating film
and laminate it, bubble free, against the PDMS transistor stamp. We find that
despite the altered design, rougher PDMS surface, and lamination and
measurement of the device in air, we still achieve electrical mobilities of
order 10 cm^2/Vs, comparable to the current state of the art in organic FETs.
Our device shows hole conduction with a threshold voltage of order -9V, which
corresponds to a trap density of 1.4 x 10^10 cm^-2.


title: Cooling a Micromechanical Beam by Coupling it to a Transmission Line

abstract:
  We study a method to cool down the vibration mode of a micro-mechanical beam
using a capacitively-coupled superconducting transmission line. The Coulomb
force between the transmission line and the beam is determined by the driving
microwave on the transmission line and the displacement of the beam. When the
frequency of the driving microwave is smaller than that of the transmission
line resonator, the Coulomb force can oppose the velocity of the beam. Thus,
the beam can be cooled. This mechanism, which may enable to prepare the beam in
its quantum ground state of vibration, is feasible under current experimental
conditions.


title: The Penna Model of Biological Aging

abstract:
  This review deals with computer simulation of biological ageing, particularly
with the Penna model of 1995.


title:
Complete Hamiltonian description of wave-like features in classical and
  quantum physics

abstract:
  The analysis of the Helmholtz equation is shown to lead to an exact
Hamiltonian system of equations describing in terms of ray trajectories a very
wide family of wave-like phenomena (including diffraction and interference)
going much beyond the limits of the ordinary geometrical optics approximation,
which is contained as a simple limiting case. Due to the fact that the time
independent Schroedinger equation is itself a Helmoltz-like equation, the same
mathematical solutions holding for a classical optical beam turn out to apply
to a quantum particle beam, leading to a complete system of Hamiltonian
equations which provide a set of particle trajectories and motion laws
containing as a limiting case the ones encountered in classical Mechanics.


title:
Production of high energy particles in laser and Coulomb fields and
  e^+e^- antenna

abstract:
  A strong laser field and the Coulomb field of a nucleus can produce
e^{+}e^{-} pairs. It is shown for the first time that there is a large
probability that electrons and positrons created in this process collide after
one or several oscillations of the laser field. These collisions can take place
at high energy resulting in several phenomena. The quasielastic collision
e^{+}e^{-} -> e^{+}e^{-} allows acceleration of leptons in the laser field to
higher energies. The inelastic collisions allow production of high energy
photons e^{+}e^{-}-> 2 gamma and muons, e^{+}e^{-} -> mu^{+}mu^{-}. The yield
of high-energy photons and muons produced via this mechanism exceeds
exponentially their production through conventional direct creation in laser
and Coulomb fields. A relation of the phenomena considered with the
antenna-mechanism of multiphoton absorption in atoms is discussed.


title: Group Testing with Random Pools: optimal two-stage algorithms

abstract:
  We study Probabilistic Group Testing of a set of N items each of which is
defective with probability p. We focus on the double limit of small defect
probability, p<<1, and large number of variables, N>>1, taking either p->0
after $N\to\infty$ or $p=1/N^{\beta}$ with $\beta\in(0,1/2)$. In both settings
the optimal number of tests which are required to identify with certainty the
defectives via a two-stage procedure, $\bar T(N,p)$, is known to scale as
$Np|\log p|$. Here we determine the sharp asymptotic value of $\bar
T(N,p)/(Np|\log p|)$ and construct a class of two-stage algorithms over which
this optimal value is attained. This is done by choosing a proper bipartite
regular graph (of tests and variable nodes) for the first stage of the
detection. Furthermore we prove that this optimal value is also attained on
average over a random bipartite graph where all variables have the same degree,
while the tests have Poisson-distributed degrees. Finally, we improve the
existing upper and lower bound for the optimal number of tests in the case
$p=1/N^{\beta}$ with $\beta\in[1/2,1)$.

categories: cs.DS cond-mat.dis-nn cond-mat.stat-mech cs.IT math.IT


title: Hadronic Final States

abstract:
  In this summary we give a concise overview of the experimental and
theoretical results, which were presented during the QCD and Hadronic Final
State Working Group sessions at the DIS 2007 workshop.


title:
Tuning the domain wall orientation in thin magnetic strips by induced
  anisotropy

abstract:
  We report on a method to tune the orientation of in-plane magnetic domains
and domain walls in thin ferromagnetic strips by manipulating the magnetic
anisotropy. Uniaxial in-plane anisotropy is induced in a controlled way by
oblique evaporation of magnetic thin strips. A direct correlation between the
magnetization direction and the domain wall orientation is found experimentally
and confirmed by micromagnetic simulations. The domain walls in the strips are
always oriented along the oblique evaporation-induced easy axis, in spite of
the shape anisotropy. The controlled manipulation of domain wall orientations
could open new possibilities for novel devices based on domain-wall
propagation.


title:
Spinorial Characterization of Surfaces into 3-dimensional homogeneous
  Manifolds

abstract:
  We give a spinorial characterization of isometrically immersed surfaces into
3-dimensional homogeneous manifolds with 4-dimensional isometry group in terms
of the existence of a particular spinor, called generalized Killing spinor.
This generalizes results by T. Friedrich for $\R^3$ and B. Morel for $\Ss^3$
and $\HH^3$. The main argument is the interpretation of the energy-momentum
tensor of a genralized Killing spinor as the second fondamental form up to a
tensor depending on the structure of the ambient space


title: Mapped Chebyshev pseudospectral method to study multiple scale phenomena

abstract:
  In the framework of mapped pseudospectral methods, we introduce a new
polynomial-type mapping function in order to describe accurately the dynamics
of systems developing almost singular structures. Using error criteria related
to the spectral interpolation error, the new polynomial-type mapping is
compared against previously proposed mappings for the study of collapse and
shock wave phenomena. As a physical application, we study the dynamics of two
coupled beams, described by coupled nonlinear Schr\"odinger equations and
modeling beam propagation in an atomic coherent media, whose spatial sizes
differs up to several orders of magnitude. It is demonstrated, also by
numerical simulations, that the accuracy properties of the new polynomial-type
mapping outperforms in orders of magnitude the ones of the other studied
mapping functions.


title:
Itinerant ferromagnetism in the multiorbital Hubbard model: a dynamical
  mean-field study

abstract:
  In order to resolve the long-standing issue of how the itinerant
ferromagnetism is affected by the lattice structure and Hund's coupling, we
have compared various three-dimensional lattice structures in the single- and
multiorbital Hubbard models with the dynamical mean-field theory with an
improved quantum Monte Carlo algorithm that preserves the spin-SU(2) symmetry.
The result indicates that {\it both} the lattice structure and the d-orbital
degeneracy are essential for the ferromagnetism in the parameter region
representing a transition metal. Specifically, (a) Hund's coupling, despite the
common belief, is important, which is here identified to come from
particle-hole scatterings, and (b) the ferromagnetism is a correlation effect
(outside the Stoner picture) as indicated from the band-filling dependence.


title: Interstellar Dust in the Solar System

abstract:
  The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse
almost perpendicular to the ecliptic plane (inclination 79 deg, perihelion
distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in
1992. The in-situ dust detector on board continuously measured interstellar
dust grains with masses up to 10^-13 kg, penetrating deep into the solar
system. The flow direction is close to the mean apex of the Sun's motion
through the solar system and the grains act as tracers of the physical
conditions in the local interstellar cloud (LIC). While Ulysses monitored the
interstellar dust stream at high ecliptic latitudes between 3 and 5 AU,
interstellar impactors were also measured with the in-situ dust detectors on
board Cassini, Galileo and Helios, covering a heliocentric distance range
between 0.3 and 3 AU in the ecliptic plane. The interstellar dust stream in the
inner solar system is altered by the solar radiation pressure force,
gravitational focussing and interaction of charged grains with the time varying
interplanetary magnetic field. We review the results from in-situ interstellar
dust measurements in the solar system and present Ulysses' latest interstellar
dust data. These data indicate a 30 deg shift in the impact direction of
interstellar grains w.r.t. the interstellar helium flow direction, the reason
of which is presently unknown.


title:
Wave-front engineering by Huygens-Fresnel principle for nonlinear
  optical interactions in domain engineered structures

abstract:
  The wave-front engineering for nonlinear optical interactions was discussed.
Using Huygens-Fresnel principle we developed a general theory and technique for
domain engineering with conventional quasi-phase-matching structures being the
special cases. By Fourier analysis we put forward the concept of local
quasi-phase matching, which suggests that the quasi-phase matching is fulfilled
only locally not globally. Experiments on focal effect of second-harmonic wave
agreed well with the theoretical prediction. The proposed scheme combines three
optical functions: generation, focusing and beam splitting of second-harmonic
wave, thus making the device more compact. Further the proposed scheme can be
used to perform the integration of multi-functional optical properties in
nonlinear photonics, as well as expand the use of nonlinear optical devices.


title:
Almost-Commutative Geometries Beyond the Standard Model III: Vector
  Doublets

abstract:
  We will present a new extension of the standard model of particle physics in
its almostcommutative formulation. This extension has as its basis the algebra
of the standard model with four summands [11], and enlarges only the particle
content by an arbitrary number of generations of left-right symmetric doublets
which couple vectorially to the U(1)_YxSU(2)_w subgroup of the standard model.
As in the model presented in [8], which introduced particles with a new colour,
grand unification is no longer required by the spectral action. The new model
may also possess a candidate for dark matter in the hundred TeV mass range with
neutrino-like cross section.


title: Bursty stellar populations and obscured AGN in galaxy bulges

abstract:
  [Abridged] We investigate trends between the recent star formation history
and black hole growth in galaxy bulges in the Sloan Digital Sky Survey (SDSS).
The galaxies lie at 0.01<z<0.07 where the fibre aperture covers only the
central 0.6-4.0kpc diameter of the galaxy. We find strong trends between black
hole growth, as measured by dust-attenuation-corrected OIII luminosity, and the
recent star formation history of the bulges. We conclude that our results
support the popular hypothesis for black hole growth occurring through gas
inflow into the central regions of galaxies, followed by a starburst and
triggering of the AGN. However, while this is a significant pathway for the
growth of black holes, it is not the dominant one in the present-day Universe.
More unspectacular processes are apparently responsible for the majority of
this growth.
  In order to arrive at these conclusions we have developed a set of new high
signal-to-noise ratio (SNR) optical spectral indicators, designed to allow a
detailed study of stellar populations which have undergone recent enhanced star
formation. Working in the rest-frame wavelength range 3750-4150AA, ideally
suited to many recent and ongoing spectroscopic surveys at low and high
redshift, the first two indices are equivalent to the previously well studied
4000AA break strength and Hdelta equivalent width. The primary advantage of
this new method is a greatly improved SNR for the latter index, allowing the
present study to use spectra with SNR-per-pixel as low as 8.


title:
Polynomial rate convergence to an invariant measure for the continuum
  time limit of the Minority Game

abstract:
  In this paper we show that the continuum time version of the Minority Game
satisfies the criteria for the application of a theorem on the existence of an
invariant measure. We consider the special case of a game with "sufficiently"
asymmetric initial condition where the number of possible choices for each
individual is S=2 and $\Gamma<+\infty$. An upper bound for the asymptotic
behavior, as the number of agents grows to infinity, of the waiting time for
reaching the stationary state is then obtained.


title: Finite jet determination of CR mappings

abstract:
  We prove the following finite jet determination result for CR mappings: Given
a smooth generic submanifold M of C^N, N >= 2, which is essentially finite and
of finite type at each of its points, for every point p on M there exists an
integer l(p), depending upper-semicontinuously on p, such that for every smooth
generic submanifold M' of C^N of the same dimension as M, if h_1 and h_2:
(M,p)->M' are two germs of smooth finite CR mappings with the same l(p) jet at
p, then necessarily their k-jets agree for all positive integers k. In the
hypersurface case, this result provides several new unique jet determination
properties for holomorphic mappings at the boundary in the real-analytic case;
in particular, it provides the finite jet determination of arbitrary
real-analytic CR mappings between real-analytic hypersurfaces in C^N of
D'Angelo finite type. It also yields a new boundary version of H. Cartan's
uniqueness theorem: if Omega and Omega' are two bounded domains in C^N with
smooth real-analytic boundary, then there exists an integer k, depending only
on the boundary of Omega, such that if H_1 and H_2: Omega -> Omega' are two
proper holomorphic mappings extending smoothly up to the boundary of Omega near
some point boundary point p and agreeing up to order k at p, then necessarily
H_1=H_2.


title: Series expansion for the density of states of the Ising and Potts models

abstract:
  An approximation of the density of states for the Ising and Potts models
based on the high- and low-temperature series are developed.


title:
How do methanol masers manage to appear in the youngest star vicinities
  and isolated molecular clumps?

abstract:
  General characteristics of methanol (CH3OH) maser emission are summarized. It
is shown that methanol maser sources are concentrated in the spiral arms. Most
of the methanol maser sources from the Perseus arm are associated with embedded
stellar clusters and a considerable portion is situated close to compact HII
regions. Almost 1/3 of the Perseus Arm sources lie at the edges of optically
identified HII regions which means that massive star formation in the Perseus
Arm is to a great extent triggered by local phenomena. A multiline analysis of
the methanol masers allows us to determine the physical parameters in the
regions of maser formation. Maser modelling shows that class II methanol masers
can be pumped by the radiation of the warm dust as well as by free-free
emission of a hypercompact region hcHII with a turnover frequency exceeding 100
GHz. Methanol masers of both classes can reside in the vicinity of hcHIIs.
Modelling shows that periodic changes of maser fluxes can be reproduced by
variations of the dust temperature by a few percent which may be caused by
variations in the brightness of the central young stellar object reflecting the
character of the accretion process. Sensitive observations have shown that the
masers with low flux densities can still have considerable amplification
factors. The analysis of class I maser surveys allows us to identify four
distinct regimes that differ by the series of their brightest lines.


title:
The structural and magnetic properties of (In1-xFex)2O3 (0.0 <= x <=
  0.25) system : prepared by gel combustion method

abstract:
  (In1-xFex)2O3 polycrystalline samples with x = (0.0, 0.05, 0.10, 0.15, 0.20
and 0.25) have been synthesized by a gel combustion method. Reitveld refinement
analysis of X raydiffraction data indicated the formation of single phase cubic
bixbyite structure without any parasitic phases. This observation is further
confirmed by high resolution transmission electron microscopy (HRTEM) imaging,
and indexing of the selected-area electron diffraction (SAED) patterns, X-ray
Absorption Spectroscopy (XAS) and Raman Spectroscopy. DC Magnetization studies
as a function of temperature and field indicatethat they are ferromagnetic with
Curie temperature (TC) well above room temperature.


title: G2 Hitchin functionals at one loop

abstract:
  We consider the quantization of the effective target space description of
topological M-theory in terms of the Hitchin functional whose critical points
describe seven-manifolds with G2 structure. The one-loop partition function for
this theory is calculated and an extended version of it, that is related to
generalized G2 geometry, is compared with the topological G2 string. We relate
the reduction of the effective action for the extended G2 theory to the Hitchin
functional description of the topological string in six dimensions. The
dependence of the partition functions on the choice of background G2 metric is
also determined.


title:
Some Thermodynamic Aspects of Pure Glue, Fuzzy Bags and Gauge/String
  Duality

abstract:
  The thermodynamic properties of a SU(3) gauge theory without quarks are
calculated using a string formulation for 1.2T_c < T < 3T_c. The results are in
good agreement with the lattice data. We also comment on SU(N) gauge theories.


title: Multi-triangulations as complexes of star polygons

abstract:
  Maximal $(k+1)$-crossing-free graphs on a planar point set in convex
position, that is, $k$-triangulations, have received attention in recent
literature, with motivation coming from several interpretations of them.
  We introduce a new way of looking at $k$-triangulations, namely as complexes
of star polygons. With this tool we give new, direct, proofs of the fundamental
properties of $k$-triangulations, as well as some new results. This
interpretation also opens-up new avenues of research, that we briefly explore
in the last section.


title:
Effects of payoff functions and preference distributions in an adaptive
  population

abstract:
  Adaptive populations such as those in financial markets and distributed
control can be modeled by the Minority Game. We consider how their dynamics
depends on the agents' initial preferences of strategies, when the agents use
linear or quadratic payoff functions to evaluate their strategies. We find that
the fluctuations of the population making certain decisions (the volatility)
depends on the diversity of the distribution of the initial preferences of
strategies. When the diversity decreases, more agents tend to adapt their
strategies together. In systems with linear payoffs, this results in dynamical
transitions from vanishing volatility to a non-vanishing one. For low signal
dimensions, the dynamical transitions for the different signals do not take
place at the same critical diversity. Rather, a cascade of dynamical
transitions takes place when the diversity is reduced. In contrast, no phase
transitions are found in systems with the quadratic payoffs. Instead, a basin
boundary of attraction separates two groups of samples in the space of the
agents' decisions. Initial states inside this boundary converge to small
volatility, while those outside diverge to a large one. Furthermore, when the
preference distribution becomes more polarized, the dynamics becomes more
erratic. All the above results are supported by good agreement between
simulations and theory.


title:
Comparative study of the inial spikes of SGR giant flares in 1998 and
  2004 observed with GEOTAIL: Do magnetospheric instabilities trigger large
  scale fracturing of magnetar's crust?

abstract:
  We present the unsaturated peak profile of SGR 1900+14 giant flare on 1998
August 27. This was obtained by particle counters of the Low Energy Particle
instrument onboard the GEOTAIL spacecraft. The observed peak profile revealed
four characteristic structures: initial steep rise, intermediate rise to the
peak, exponential decay and small hump in the decay phase. From this light
curve, we found that the isotropic peak luminosity was $2.3\times10^{46}$ erg
s$^{-1}$ and the total energy was $4.3 \times 10^{44}$ erg s$^{-1}$ ($E\gtrsim$
50 keV), assuming that the distance to SGR 1900+14 is 15 kpc and that the
spectrum is optically thin thermal bremsstrahlung with $kT =$ 240 keV. These
are consistent with the previously reported lower limits derived from Ulysses
and Konus-Wind observations. A comparative study of the initial spikes of SGR
1900+14 giant flare in 1998 and SGR 1806-20 in 2004 is also presented. The
timescale of the initial steep rise shows the magnetospheric origin, while the
timescale of the intermediate rise to the peak indicates that it originates
from the crustal fracturing. Finally, we argue that the four structures and
their corresponding timescales provide a clue to identify extragalactic SGR
giant flares among short GRBs.


title: The Non-Trapping Degree of Scattering

abstract:
  We consider classical potential scattering. If no orbit is trapped at energy
E, the Hamiltonian dynamics defines an integer-valued topological degree. This
can be calculated explicitly and be used for symbolic dynamics of
multi-obstacle scattering.
  If the potential is bounded, then in the non-trapping case the boundary of
Hill's Region is empty or homeomorphic to a sphere.
  We consider classical potential scattering. If at energy E no orbit is
trapped, the Hamiltonian dynamics defines an integer-valued topological degree
deg(E) < 2. This is calculated explicitly for all potentials, and exactly the
integers < 2 are shown to occur for suitable potentials.
  The non-trapping condition is restrictive in the sense that for a bounded
potential it is shown to imply that the boundary of Hill's Region in
configuration space is either empty or homeomorphic to a sphere.
  However, in many situations one can decompose a potential into a sum of
non-trapping potentials with non-trivial degree and embed symbolic dynamics of
multi-obstacle scattering. This comprises a large number of earlier results,
obtained by different authors on multi-obstacle scattering.


title: Spatial string tension in $N_f=2$ lattice QCD at finite temperature

abstract:
  The spatial string tension across a crossover from the low temperature phase
to the high temperature phase is computed in QCD with two flavors of
non-perturbatively improved Wilson fermions at small lattice spacing a \sim
0.12fm. We find that in the low temperature phase spatial string tension agrees
well with zero temperature string tension. Furthermore, it does not show
increasing for temperatures up to T = 1.36 T_{pc}, the highest temperature
considered. Our results agree with some theoretical predictions.


title:
On the structure of relativistic collisionless shocks in electron-ion
  plasmas

abstract:
  Relativistic collisionless shocks in electron-ion plasma are thought to occur
in the afterglow phase of Gamma-Ray Bursts (GRBs), and in other environments
where relativistic flows interact with the interstellar medium. A particular
regime of shocks in an unmagnetized plasma has generated much interest for GRB
applications. In this paper we present ab-initio particle-in-cell simulations
of unmagnetized relativistic electron-ion shocks. Using long-term
2.5-dimensional simulations with ion-electron mass ratios from 16 to 1000 we
resolve the shock formation and reach a steady-state shock structure beyond the
initial transient. We find that even at high ion-electron mass ratios initially
unmagnetized shocks can be effectively mediated by the ion Weibel instability
with a typical shock thickness of ~50 ion skin-depths. Upstream of the shock
the interaction with merging ion current filaments heats the electron
component, so that the postshock flow achieves near equipartition between the
ions and electrons, with electron temperature reaching 50% of the ion
temperature. This energy exchange helps to explain the large electron energy
fraction inferred from GRB afterglow observations.


title: Brane-Worlds Pseudo-Goldstinos

abstract:
  We consider a space-time with extra dimensions containing sectors, branes and
bulk, that communicate only through gravitational interactions. In each sector,
if considered separately, supersymmetry could be spontaneously broken, leading
to the appearance of Goldstinos. However, when taken all together, only certain
combinations of the latter states turn out to be true ``would be Goldstinos'',
eaten by the gravitinos. The other (orthogonal) combinations, we call
pseudo-Goldstinos, remain in the low energy spectrum. We discuss explicitly how
this happen in the simplest set-up of five-dimensional space compactified on
S^1/Z_2 . Our results divide into two parts that can be considered separately.
First, we build an extension of the bulk five-dimensional supergravity, by a
set of new auxiliary fields, that allows coupling it to branes where
supersymmetry is spontaneously broken. Second, we discuss in details the super
Higgs mechanism in the R_\xi and unitary gauges, in the presence of both of a
bulk Scherk-Schwarz mechanism and brane localized F-terms. This leads us to
compute the gravitino mass and provide explicit formulae for the
pseudo-Goldstinos spectrum.


title: Gamma-delayed deuteron emission of the 6Li (0+;T=1) halo state

abstract:
  M1 transitions from the $^6$Li($0^+;T=1$) state at 3.563 MeV to the
$^6$Li($1^+$) ground state and to the $\alpha+d$ continuum are studied in a
three-body model. The bound states are described as an $\alpha+n+p$ system in
hyperspherical coordinates on a Lagrange mesh. The ground-state magnetic moment
and the gamma width of the $^6$Li(0$^+$) resonance are well reproduced. The
halo-like structure of the $^6$Li$(0^+)$ resonance is confirmed and is probed
by the M1 transition probability to the $\alpha+d$ continuum. The spectrum is
sensitive to the description of the $\alpha+d$ phase shifts. The corresponding
gamma width is around 1.0 meV, with optimal potentials. Charge symmetry is
analyzed through a comparison with the $\beta$-delayed deuteron spectrum of
$^6$He. In $^6$He, a nearly perfect cancellation effect between short-range and
halo contributions was found. A similar analysis for the $^6$Li($0^+;T=1$)
$\gamma$ decay is performed; it shows that charge-symmetry breaking at large
distances, due to the different binding energies and to different charges,
reduces this effect. The present branching ratio $\Gamma_{\gamma}(0^+\to
\alpha+d)/\Gamma_{\gamma}(0^+\to1^+)\approx 1.3\times 10^{-4}$ should be
observable with current experimental facilities.


title:
Closed-Form Density of States and Localization Length for a
  Non-Hermitian Disordered System

abstract:
  We calculate the Lyapunov exponent for the non-Hermitian Zakharov-Shabat
eigenvalue problem corresponding to the attractive non-linear Schroedinger
equation with a Gaussian random pulse as initial value function. Using an
extension of the Thouless formula to non-Hermitian random operators, we
calculate the corresponding average density of states. We analyze two cases,
one with circularly symmetric complex Gaussian pulses and the other with real
Gaussian pulses. We discuss the implications in the context of the information
transmission through non-linear optical fibers.

categories: cond-mat.dis-nn cond-mat.stat-mech cs.IT math.IT nlin.SI


title:
Abelian Magnetic Monopoles and Topologically Massive Vector Bosons in
  Scalar-Tensor Gravity with Torsion Potential

abstract:
  A Lagrangian formulation describing the electromagnetic interaction -
mediated by topologically massive vector bosons - between charged, spin-(1/2)
fermions with an abelian magnetic monopole in a curved spacetime with
non-minimal coupling and torsion potential is presented. The covariant field
equations are obtained. The issue of coexistence of massive photons and
magnetic monopoles is addressed in the present framework. It is found that
despite the topological nature of photon mass generation in curved spacetime
with isotropic dilaton field, the classical field theory describing the
nonrelativistic electromagnetic interaction between a point-like electric
charge and magnetic monopole is inconsistent.


title: A nilpotent quotient algorithm for L-presented groups

abstract:
  The main part of this paper contains a description of a nilpotent quotient
algorithm for L-presented groups and a report on applications of its
implementation in the computer algebra system GAP. The appendix introduces two
new infinite series of L-presented groups. Apart from being of interest in
their own right, these new L-presented groups serve as examples for
applications of the nilpotent quotient algorithm.


title: EasyVoice: Integrating voice synthesis with Skype

abstract:
  This paper presents EasyVoice, a system that integrates voice synthesis with
Skype. EasyVoice allows a person with voice disabilities to talk with another
person located anywhere in the world, removing an important obstacle that
affect these people during a phone or VoIP-based conversation.


title:
Tunable photonic band gaps with coherently driven atoms in optical
  lattices

abstract:
  Optical lattice loaded with cold atoms can exhibit a tunable photonic band
gap for a weak probe field under the conditions of electromagnetically induced
transparency. This system possesses a number of advantageous properties,
including reduced relaxation of Raman coherence and the associated probe
absorption, and simultaneous enhancement of the index modulation and the
resulting reflectivity of the medium. This flexible system has a potential to
serve as a testbed of various designs for the linear and nonlinear photonic
band gap materials at a very low light level and can be employed for realizing
deterministic entanglement between weak quantum fields.


title: Triadophilia: A Special Corner in the Landscape

abstract:
  It is well known that there are a great many apparently consistent vacua of
string theory. We draw attention to the fact that there appear to be very few
Calabi--Yau manifolds with the Hodge numbers h^{11} and h^{21} both small. Of
these, the case (h^{11}, h^{21})=(3,3) corresponds to a manifold on which a
three generation heterotic model has recently been constructed. We point out
also that there is a very close relation between this manifold and several
familiar manifolds including the `three-generation' manifolds with \chi=-6 that
were found by Tian and Yau, and by Schimmrigk, during early investigations. It
is an intriguing possibility that we may live in a naturally defined corner of
the landscape. The location of these three generation models with respect to a
corner of the landscape is so striking that we are led to consider the
possibility of transitions between heterotic vacua. The possibility of these
transitions, that we here refer to as transgressions, is an old idea that goes
back to Witten. Here we apply this idea to connect three generation vacua on
different Calabi-Yau manifolds.


title: Excited $(70,L^+)$ baryon resonances in the relativistic quark model

abstract:
  The masses of positive parity $(70,0^+)$ and $(70,2^+)$ nonstrange and
strange baryons are calculated in the relativistic quark model. The
relativistic three-quark equations of the $(70,L^+)$ multiplets are found in
the framework of the dispersion relation technique. The approximate solutions
of these equations using the method based on the extraction of leading
singularities of the amplitude are obtained. The calculated mass values of the
$(70,L^+)$ multiplets are in good agreement with the experimental ones.


title:
Broad distribution of stick-slip events in Slowly Sheared Granular
  Media: Table-top production of a Gutenberg-Richter-like distribution

abstract:
  We monitor the stick-slip displacements of a very slowly driven moveable
perforated top plate which interacts via shearing with a packing of identical
glass beads confined in a tray. When driven at a constant stress rate, the
distributions of large event displacements and energies triggered by the
stick-slip instabilities exhibit power law responses reminiscent of the
Gutenberg-Richter law for earthquakes. Small events are quasi-size independent,
signaling crossover from single-bead transport to collective behavior.


title: Asymptotic Enumeration of RNA Structures with Pseudoknots

abstract:
  In this paper we present the asymptotic enumeration of RNA structures with
pseudoknots. We develop a general framework for the computation of exponential
growth rate and the sub exponential factors for $k$-noncrossing RNA structures.
Our results are based on the generating function for the number of
$k$-noncrossing RNA pseudoknot structures, ${\sf S}_k(n)$, derived in
\cite{Reidys:07pseu}, where $k-1$ denotes the maximal size of sets of mutually
intersecting bonds. We prove a functional equation for the generating function
$\sum_{n\ge 0}{\sf S}_k(n)z^n$ and obtain for $k=2$ and $k=3$ the analytic
continuation and singular expansions, respectively. It is implicit in our
results that for arbitrary $k$ singular expansions exist and via transfer
theorems of analytic combinatorics we obtain asymptotic expression for the
coefficients. We explicitly derive the asymptotic expressions for 2- and
3-noncrossing RNA structures. Our main result is the derivation of the formula
${\sf S}_3(n) \sim \frac{10.4724\cdot 4!}{n(n-1)...(n-4)}
(\frac{5+\sqrt{21}}{2})^n$.


title: Insights and puzzles in light quark physics

abstract:
  Recent work in light flavour hadron physics is reviewed. In particular, I
discuss the significance of the progress achieved with light dynamical quarks
on the lattice for the effective low energy theory of QCD. Also, I draw
attention to some puzzling results from NA48 and KTeV concerning the scalar
form factor relevant for Kmu3 decay -- taken at face value, these indicate
physics beyond the Standard Model.


title: Exclusive Meson Production at NLO

abstract:
  We report on numerical studies of the NLO corrections to exclusive meson
electroproduction, both in collider and fixed-target kinematics. Corrections
are found to be huge at small xB and sizeable at intermediate or large xB.


title:
Saffman-Taylor instability in a non-Brownian suspension: finger
  selection and destabilization

abstract:
  We study the Saffman-Taylor instability in a non-Brownian suspension by
injection of air. We find that flow structuration in the Hele-Shaw cell can be
described by an effective viscosity depending on the volume fraction. When this
viscosity is used to define the control parameter of the instability, the
classical finger selection for Newtonian fluids is recovered. However, this
picture breaks down when the cell thickness is decreased below approximatively
10 grain sizes. The discrete nature of the grains plays also a determinant role
in the the early destabilization of the fingers observed. The grains produce a
perturbation at the interface proportional to the grain size and can thus be
considered as a "controlled noise". The finite amplitude instability mechanism
proposed earlier by Bensimon et al. allows to link this perturbation to the
actual values of the destabilization threshold.


title: Higher-Order Calculus of Variations on Time Scales

abstract:
  We prove a version of the Euler-Lagrange equations for certain problems of
the calculus of variations on time scales with higher-order delta derivatives.


title: Three-point correlations for quantum star graphs

abstract:
  We compute the three point correlation function for the eigenvalues of the
Laplacian on quantum star graphs in the limit where the number of edges tends
to infinity. This extends a work by Berkolaiko and Keating, where they get the
2-point correlation function and show that it follows neither Poisson, nor
random matrix statistics. It makes use of the trace formula and combinatorial
analysis.


title:
First Order Superfluid to Bose Metal Transition in Systems with Resonant
  Pairing

abstract:
  Systems showing resonant superfluidity, driven by an exchange coupling of
strength $g$ between uncorrelated pairs of itinerant fermions and tightly bound
ones, undergo a first order phase transition as $g$ increases beyond some
critical value $g_c$. The superfluid phase for $g \leq g_c$ is characterized by
a gap in the fermionic single particle spectrum and an acoustic sound-wave like
collective mode of the bosonic resonating fermion pairs inside this gap. For
$g>g_c$ this state gives way to a phase uncorrelated bosonic liquid with a
$q^2$ spectrum.


title:
Comment on the paper "Weyssenhoff fluid dynamics in a 1+3 covariant
  approach" (arXiv:0706.2367)

abstract:
  Few comments are given to clarify some issues of Weyssenhoff fluid in the
Einstein-Cartan gravity.


title: Revisiting Signature of Minimal Gauge Mediation

abstract:
  We revisit phenomenology of the minimal gauge-mediated model. This model is
motivated from the SUSY CP and flavor problems. A specific feature of this
model is that \tan\beta is naturally large, since the B term in the Higgs
potential is zero at the messenger scale. This leads to significant SUSY
contributions to various low-energy observables. We evaluate the anomalous
magnetic moment of the muon and the branching ratio of \bar{B}\to X_s\gamma
taking account of recent theoretical and experimental developments. We find
that the current experimental data prefer a low messenger scale (\sim 100 TeV)
and gluino mass around 1 TeV. We also calculate the branching ratios of
\bar{B}\to X_s l^+l^-, B_s\to \mu^+\mu^-, and B^-\to \tau^- \bar{\nu}, and show
that these observables are strongly correlated with each other in this model.


title: WiFi Epidemiology: Can Your Neighbors' Router Make Yours Sick?

abstract:
  In densely populated urban areas WiFi routers form a tightly interconnected
proximity network that can be exploited as a substrate for the spreading of
malware able to launch massive fraudulent attack and affect entire urban areas
WiFi networks. In this paper we consider several scenarios for the deployment
of malware that spreads solely over the wireless channel of major urban areas
in the US. We develop an epidemiological model that takes into consideration
prevalent security flaws on these routers. The spread of such a contagion is
simulated on real-world data for geo-referenced wireless routers. We uncover a
major weakness of WiFi networks in that most of the simulated scenarios show
tens of thousands of routers infected in as little time as two weeks, with the
majority of the infections occurring in the first 24 to 48 hours. We indicate
possible containment and prevention measure to limit the eventual harm of such
an attack.


title: Half-Supersymmetric Solutions in Five-Dimensional Supergravity

abstract:
  We present a systematic classification of half-supersymmetric solutions of
gauged N=2, D=5 supergravity coupled to an arbitrary number of abelian vector
multiplets for which at least one of the Killing spinors generate a time-like
Killing vector.


title:
Finite size effects on surface excess quantities: application to crystal
  growth and surface melting of epitaxial layers

abstract:
  From a macroscopic point of view phase transitions as surface melting or two
dimensional (2D) towards three dimensional (3D) growth mode (Stranski-Krastanov
transition) can be described in terms of Gibbs excess quantity duly amended by
size effects (since usual Gibbs excess quantities are only well defined for
semi-infinite systems). The aim of this study is to consider such amended
quantities to describe surface melting and Stranski-Krastanov transition of
epitaxial layers. the so-introduced size effects allows us to predict the
equilibrium thickness of the wetting layer of the Stranski-Krastanov growth
mode and to describe and classify two different melting cases: the incomplete
melting relayed by a first order transition and the continuous premelting
relayed by continuous overheating


title:
Probing the truncation of galaxy dark matter halos in high density
  environments from hydrodynamical N-body simulations

abstract:
  We analyze high resolution, N-body hydrodynamical simulations of fiducial
galaxy clusters to probe tidal stripping of the dark matter subhalos. These
simulations include a prescription for star formation allowing us to track the
fate of the stellar component as well. We investigate the effect of tidal
stripping on cluster galaxies hosted in these dark matter subhalos as a
function of cluster-centric radius. To quantify the extent of the dark matter
halos of cluster galaxies, we introduce the half mass radius r_half as a
diagnostic, and study its evolution with projected cluster-centric distance R
as a function of redshift. We find a well defined trend for (r_half,R): the
closer the galaxies are to the center of the cluster, the smaller the half mass
radius. Interestingly, this trend is inferred in all redshift frames examined
in this work ranging from z=0 to z=0.7. At z=0, galaxy halos in the central
regions of clusters are found to be highly truncated, with the most compact
half mass radius of 10 kpc. We also find that r_half depends on luminosity and
we present scaling relations of r_half with galaxy luminosity. The
corresponding total mass of the cluster galaxies is also found to increase with
projected cluster-centric distance and luminosity, but with more scatter than
the (r_half,R) trend. Comparing the distribution of stellar mass to total mass
for cluster galaxies, we find that the dark matter component is preferentially
stripped, whereas the stellar component remains protected by the halo and is
much less affected by tidal forces. We compare these results with galaxy-galaxy
lensing probes of r_half and find qualitative agreement. (Abridged)


title:
Measurement of the Cross Section for open b-Quark Production in
  Two-Photon Interactions at LEP

abstract:
  Inclusive beauty-quark production in two-photon collisions has been measured
at LEP using an integrated luminosity of 698 pb-1 collected by the ALEPH
detector with sqrt(s) between 130 and 209 GeV. The b quarks were identified
using lifetime information. The cross section is found to be sigma(e+ e- --> e+
e- b \bar{b} X) = (5.4 +/- 0.8 (stat) +/- 0.8 (syst)) pb which is consistent
with Next-to-Leading Order QCD.


title: Meta-stable A_n quiver gauge theories

abstract:
  We study metastable dynamical breaking of supersymmetry in A_n quiver gauge
theories. We present a general analysis and criteria for the perturbative
existence of metastable vacua in quivers of any length. Different mechanisms of
gauge mediation can be realized.


title: Remarks on the calculus of variations on time scales

abstract:
  The calculus of variations is a classical subject which has gain throughout
the last three hundred years a level of rigor and elegance that only time can
give. In this note we show that, contrary to the classical field, available
formulations and results on the recent calculus of variations on time scales
are still at the heuristic level.


title: Connections between Romanovski and other polynomials

abstract:
  A connection between Romanovski polynomials and those polynomials that solve
the one-dimensional Schr\"odinger equation with the trigonometric Rosen-Morse
and hyperbolic Scarf potential is established. The map is constructed by
reworking the Rodrigues formula in an elementary and natural way. The
generating function is summed in closed form from which recursion relations and
addition theorems follow. Relations to some classical polynomials are also
given.


title: M31 and Local Group QSO's

abstract:
  Previous analyses have shown companion galaxies aligned along the minor axis
of M31. The alignment includes some galaxies of higher redshift than
conventionally accepted for Local Group members. Here we look at the
distribution of all high redshift objects listed in a 10 x 10 deg. area around
M31. We find not only galaxies of higher redshift but also quasars along the
minor axis of this brightest Local Group galaxy, Some are an unusual class of
low z, quasar-galaxy.
  Previously observers had noted radio sources aligned along the minor axis of
M31. The ejection directions of quasars from active galaxy nuclei is also along
the minor axis within a cone of about 20 deg. opening angle. It is shown here
that the quasar-like and higher redshift objects associated with M31 are
relatively concentrated along this axis.
  M33 also falls closely along the minor axis of M31 and the famous 3C48 and
similar redshift galaxy/quasars are seen along a line coming from this Local
Group companion of M31. What appears to be dusty nebulosity has also been shown
to exist along this extended line in the sky.


title: Collider Phenomenology of Unparticle Physics

abstract:
  Low energy phenomenology of the unparticle physics associated with an exact
scale invariant sector possessing a non-trivial infrared fixed point at a
higher energy scale is explored for both electron-positron and hadronic
colliders. Feynman rules for a spin 0, 1 or 2 unparticle coupled to a variety
of standard model gauge invariant operators that are relevant to many low
energy processes involving either real emissions of unparticles or their
virtual propagator effects are presented. Missing energy and/or recoil mass
distributions of the unparticle in the associated production of unparticle
together with a photon or $Z$ boson at LEP2 and ILC as well as in $Z$ decay
into an unparticle plus a fermion-antifermion pair are studied. Monojet
production at hadronic collisions is explored. The complex phase in the
unparticle propagator that can give rise to interesting interference effects
between an unparticle exchange diagram and the standard model amplitudes are
studied in details for the Drell-Yan process as well as muon pair and diphoton
production in electron-positron annihilation. These energy and/or recoil mass
distributions (with the exception in hadron colliders) and interference effects
are found sensitively depending not only on the scale dimension but also on the
spin of the unparticle. For the spin-2 unparticle, its physical effects is
found to resemble that of a tower of Kaluza-Klein gravitons, which strongly
indicates that the underlying unparticle physics may have root in a higher
dimensional theory. A connection between unparticle physics and theories of
large extra dimension is speculated. Experimental constraints on the unparticle
scale are deduced from the LEP2 data on mono-photon production and from the
4-fermion contact interactions.


title: Interfaces and the edge percolation map of random directed networks

abstract:
  The traditional node percolation map of directed networks is reanalyzed in
terms of edges. In the percolated phase, edges can mainly organize into five
distinct giant connected components, interfaces bridging the communication of
nodes in the strongly connected component and those in the in- and
out-components. Formal equations for the relative sizes in number of edges of
these giant structures are derived for arbitrary joint degree distributions in
the presence of local and two-point correlations. The uncorrelated null model
is fully solved analytically and compared against simulations, finding an
excellent agreement between the theoretical predictions and the edge
percolation map of synthetically generated networks with exponential or
scale-free in-degree distribution and exponential out-degree distribution.
Interfaces, and their internal organization giving place from "hairy ball"
percolation landscapes to bottleneck straits, could bring new light to the
discussion of how structure is interwoven with functionality, in particular in
flow networks.


title: Power corrections for jets at hadron colliders

abstract:
  We discuss non-perturbative QCD corrections to jet distributions in hadron
collisions, focussing on hadronisation and underlying event contributions.
Using soft gluon resummation and Monte-Carlo modelling we show that
hadronisation dominates at small values of the jet radius R, behaving as 1/R,
while underlying event corrections grow with the jet area. This provides a
handle to disentangle them and parametrize them in terms of measurable QCD
parameters, which might enjoy a degree of universality.


title: On contact tops and integrable tops

abstract:
  In this paper, we introduce a geometric structure called top, which is a
trivialized bundle of plane pencils over a Riemannian 3-manifold, defined as
the set of kernels of a circle of 1-forms (e.g. of contact and integrable
forms) with particular properties with respect to the metric. We classify the
manifolds which admit tops and we describe the associated metrics.


title:
Une s\'emantique observationnelle du mod\`ele des bo\^ites pour la
  r\'esolution de programmes logiques (version \'etendue)

abstract:
  This report specifies an observational semantics and gives an original
presentation of the Byrd's box model. The approach accounts for the semantics
of Prolog tracers independently of a particular implementation. Traces are, in
general, considered as rather obscure and difficult to use. The proposed formal
presentation of a trace constitutes a simple and pedagogical approach for
teaching Prolog or for implementing Prolog tracers. It constitutes a form of
declarative specification for the tracers. Our approach highlights qualities of
the box model which made its success, but also its drawbacks and limits. As a
matter of fact, the presented semantics is only one example to illustrate
general problems relating to tracers and observing processes. Observing
processes know, from observed processes, only their traces. The issue is then
to be able to reconstitute by the sole analysis of the trace the main part of
the observed process, and if possible, without any loss of information.


title: Spin pumping by a field-driven domain wall

abstract:
  We calculate the charge current in a metallic ferromagnet to first order in
the time derivative of the magnetization direction. Irrespective of the
microscopic details, the result can be expressed in terms of the conductivities
of the majority and minority electrons and the non-adiabatic spin transfer
torque parameter $\beta$. The general expression is evaluated for the specific
case of a field-driven domain wall and for that case depends strongly on the
ratio of $\beta$ and the Gilbert damping constant. These results may provide an
experimental method to determine this ratio, which plays a crucial role for
current-driven domain-wall motion.


title: Euler Walk on a Cayley Tree

abstract:
  We show that the Euler walk on a Cayley tree exhibits two regimes (dynamic
phases): a condensed phase and a low-density phase. In the condensed phase the
self-organized area grows as a compact domain. In the low-density phase the
proportion of self-organized (visited) nodes decreases rapidly from one
generation of the tree to the next. We describe in detail returns of the Euler
walk to the root and growth of the self-organized domain in the condensed
phase. We also investigate the critical behaviour of the Euler walk at the
point separating the two regimes.


title:
Remarks on the density of the law of the occupation time for Bessel
  bridges and stable excursions

abstract:
  Smoothness and asymptotic behaviors are studied for the densities of the law
of the occupation time on the positive line for Bessel bridges and the
normalized excursion of strictly stable processes. The key role is played by
these properties for functions defined by Riemann--Liouville fractional
integrals.


title: Verhulst's logistic curve

abstract:
  We observe that the elementary logistic differential equation dP/dt=(1-P/M)kP
may be solved by first changing the variable to R=(M-P)/P. This reduces the
logistic differential equation to the simple linear differential equation
dR/dt=-kR, which can be solved without using the customary but slightly more
elaborate methods applied to the original logistic DE. The resulting solution
in terms of R can be converted by simple algebra to the familiar sigmoid
expression involving P. A biological argument is given for introducing logistic
growth via the simpler DE for R. It is also shown that the sigmoid P may be
written in terms of the hyperbolic tangent by a simple translation that is also
motivated by a biological argument.


title: Poisson sigma model on the sphere

abstract:
  We evaluate the path integral of the Poisson sigma model on sphere and study
the correlators of quantum observables. We argue that for the path integral to
be well-defined the corresponding
  Poisson structure should be unimodular. The construction of the finite
dimensional BV theory is presented and we argue that it is responsible for the
leading semiclassical contribution. For a (twisted) generalized Kahler manifold
we discuss the gauge fixed action for the Poisson sigma model. Using the
localization we prove that for the holomorphic Poisson structure the
semiclassical result for the correlators is indeed the full quantum result.


title:
A solution for actors' viewpoints representation with collaborative
  product development

abstract:
  As product complexity and marketing competition increase, a collaborative
product development is necessary for companies which develop high quality
products in short lead-times. To support product actors from different fields,
disciplines, and locations, wishing to exchange and share information, the
representation of the actors' viewpoints is the underlying requirement of the
collaborative product development. The actors' viewpoints approach was designed
to provide an organisational framework following the actors' perspectives in
the collaboration, and their relationships, could be explicitly gathered and
formatted. The approach acknowledges the inevitability of multiple integration
of product information as different views, promotes gathering of actors'
interests, and encourages retrieved adequate information while providing
support for integration through PLM and/or SCM collaboration. In this paper, a
solution for neutral viewpoints representation is proposed. The product,
process, and organisation information models are seriatim discussed. A series
of issues referring to the viewpoints representation are discussed in detail.
Based on XML standard, taking cyclone vessel as an example, an application case
of part of product information modelling is stated.


title:
The Equations of Motion of a Charged Particle in the Five-Dimensional
  Model of the General Relativity Theory with the Four-Dimensional Nonholonomic
  Velocity Space

abstract:
  We consider the four-dimensional nonholonomic distribution defined by the
4-potential of the electromagnetic field on the manifold. This distribution has
a metric tensor with the Lorentzian signature $(+,-,-,-)$, therefore, the
causal structure appears as in the general relativity theory. By means of the
Pontryagin's maximum principle we proved that the equations of the horizontal
geodesics for this distribution are the same as the equations of motion of a
charged particle in the general relativity theory. This is a Kaluza -- Klein
problem of classical and quantum physics solved by methods of sub-Lorentzian
geometry. We study the geodesics sphere which appears in a constant magnetic
field and its singular points. Sufficiently long geodesics are not optimal
solutions of the variational problem and define the nonholonomic wavefront.
This wavefront is limited by a convex elliptic cone. We also study variational
principle approach to the problem. The Euler -- Lagrange equations are the same
as those obtained by the Pontryagin's maximum principle if the restriction of
the metric tensor on the distribution is the same.

categories: math.DG gr-qc math.MG math.OC physics.class-ph


title:
Production of a sterile species via active-sterile mixing: an exactly
  solvable model

abstract:
  The production of a sterile species via active-sterile mixing in a thermal
medium is studied in an exactly solvable model. The \emph{exact} time evolution
of the sterile distribution function is determined by the dispersion relations
and damping rates $\Gamma_{1,2}$ for the quasiparticle modes. These depend on
$\wtg = \Gamma_{aa}/2\Delta E$, with $\Gamma_{aa}$ the interaction rate of the
active species in absence of mixing and $\Delta E$ the oscillation frequency in
the medium without damping. $\wtg \ll1,\wtg \gg 1$ describe the weak and strong
damping limits respectively. For $\wtg\ll1$, $\Gamma_1 = \Gamma_{aa}\cos^2\tm ;
\Gamma_{2}=\Gamma_{aa}\sin^2\tm$ where $\tm$ is the mixing angle in the medium
and the sterile distribution function \emph{does not} obey a simple rate
equation. For $\wtg \gg 1$, $\Gamma_1= \Gamma_{aa}$ and $\Gamma_2 = \Gamma_{aa}
\sin^22\tm/4\wtg^2$, is the sterile production rate. In this regime sterile
production is suppressed and the oscillation frequency \emph{vanishes} at an
MSW resonance, with a breakdown of adiabaticity. These are consequences of
quantum Zeno suppression. For active neutrinos with standard model interactions
the strong damping limit is \emph{only} available near an MSW resonance
\emph{if} $\sin\theta \lesssim \alpha_w$ with $\theta$ the vacuum mixing angle.
The full set of quantum kinetic equations for sterile production for arbitrary
$\wtg$ are obtained from the quantum master equation. Cosmological resonant
sterile neutrino production is quantum Zeno suppressed relieving potential
uncertainties associated with the QCD phase transition.


title: Fluctuations and the clustering of color sources

abstract:
  We present our results on multiplicity and $p_T$ fluctuations at LHC energies
in the framework of the clustering of color sources. In this approach,
elementary color sources -strings- overlap forming clusters, so the number of
effective sources is modified. We find that the fluctuations are proportional
to the number of those clusters.


title: N=1* model superpotential revisited (IR behaviour of N=4 limit)

abstract:
  The one-loop contribution to the superpotential, in particular the
Veneziano-Yankielowicz potential in N=1 supersymmetric Yang-Mills model is
discussed from an elementary field theory method and the matrix model point of
view. Both approaches are based on the Renormalization Group variation of the
superconformal N=4 supersymmetric Yang-Mills model.