title: Aspects of warped braneworld models

abstract:
  We review various key issues in connection with the warped braneworld models
which provide us with new insights and explanations of physical phenomena
through interesting geometrical features of such extra dimensional theories.
Starting from the original Randall-Sundrum two brane models, we have discussed
the stability, hierarchy and other important issues in connection with such
braneworld. The role of higher derivative terms in the bulk for modulus
stabilization has been explained. Implications of the existence of various bulk
fields have been discussed and it has been shown how a warped braneworld model
can explain the invisibility of all antisymmetric bulk tensor fields on our
brane. We have also generalised the model for more than one warped dimensions
in the form of a multiply warped spacetime. It is shown that such model can
offer an explanation to the mass hierarchy among the standard model fermions
and the localization of fermions on the standard model brane with a definite
chirality.


title: Self-stabilizing K-out-of-L exclusion on tree network

abstract:
  In this paper, we address the problem of K-out-of-L exclusion, a
generalization of the mutual exclusion problem, in which there are $\ell$ units
of a shared resource, and any process can request up to $\mathtt k$ units
($1\leq\mathtt k\leq\ell$). We propose the first deterministic self-stabilizing
distributed K-out-of-L exclusion protocol in message-passing systems for
asynchronous oriented tree networks which assumes bounded local memory for each
process.


title:
S\'election de la structure d'un perceptron multicouches pour la
  r\'eduction dun mod\`ele de simulation d'une scierie

abstract:
  Simulation is often used to evaluate the relevance of a Directing Program of
Production (PDP) or to evaluate its impact on detailed sc\'enarii of
scheduling. Within this framework, we propose to reduce the complexity of a
model of simulation by exploiting a multilayer perceptron. A main phase of the
modeling of one system using a multilayer perceptron remains the determination
of the structure of the network. We propose to compare and use various pruning
algorithms in order to determine the optimal structure of the network used to
reduce the complexity of the model of simulation of our case of application: a
sawmill.


title:
A simulation study on the measurement of D0-D0bar mixing parameter y at
  BES-III

abstract:
  We established a method on measuring the $\dzdzb$ mixing parameter $y$ for
BESIII experiment at the BEPCII $e^+e^-$ collider. In this method, the doubly
tagged $\psi(3770) \to D^0 \overline{D^0}$ events, with one $D$ decays to
CP-eigenstates and the other $D$ decays semileptonically, are used to
reconstruct the signals. Since this analysis requires good $e/\pi$ separation,
a likelihood approach, which combines the $dE/dx$, time of flight and the
electromagnetic shower detectors information, is used for particle
identification. We estimate the sensitivity of the measurement of $y$ to be
0.007 based on a $20fb^{-1}$ fully simulated MC sample.


title: Non-Markovian weak coupling limit of quantum Brownian motion

abstract:
  We derive and solve analytically the non-Markovian master equation for
harmonic quantum Brownian motion proving that, for weak system-reservoir
couplings and high temperatures, it can be recast in the form of the master
equation for a harmonic oscillator interacting with a squeezed thermal bath.
This equivalence guarantees preservation of positivity of the density operator
during the time evolution and allows one to establish a connection between the
dynamics of Schr\"odinger cat states in squeezed environments and
environment-induced decoherence in quantum Brownian motion.


title:
Observing the clustering properties of galaxy clusters in dynamical
  dark-energy cosmologies

abstract:
  We study the clustering properties of galaxy clusters expected to be observed
by various forthcoming surveys both in the X-ray and sub-mm regimes by the
thermal Sunyaev-Zel'dovich effect. Several different background cosmological
models are assumed, including the concordance $\Lambda$CDM and various
cosmologies with dynamical evolution of the dark energy. Particular attention
is paid to models with a significant contribution of dark energy at early times
which affects the process of structure formation. Past light cone and selection
effects in cluster catalogs are carefully modeled by realistic scaling
relations between cluster mass and observables and by properly taking into
account the selection functions of the different instruments. The results show
that early dark-energy models are expected to produce significantly lower
values of effective bias and both spatial and angular correlation amplitudes
with respect to the standard $\Lambda$CDM model. Among the cluster catalogues
studied in this work, it turns out that those based on \emph{eRosita},
\emph{Planck}, and South Pole Telescope observations are the most promising for
distinguishing between various dark-energy models.


title: Novel Photo-Detectors and Photo-Detector Systems

abstract:
  Recent developments in photo-detectors and photo-detector systems are
reviewed. The main emphasis is made on Silicon Photo-Multipliers (SiPM) - novel
and very attractive photo-detectors. Their main features are described.
Properties of detectors manufactured by different producers are compared.
Different applications are discussed including calorimeters, muon detection,
tracking, Cherenkov light detection, and time of flight measurements.


title: Asymptotics of one-dimensional forest fire processes

abstract:
  We consider the so-called one-dimensional forest fire process. At each site
of $\mathbb{Z}$, a tree appears at rate $1$. At each site of $\mathbb{Z}$, a
fire starts at rate ${\lambda}>0$, immediately destroying the whole
corresponding connected component of trees. We show that when ${\lambda}$ is
made to tend to $0$ with an appropriate normalization, the forest fire process
tends to a uniquely defined process, the dynamics of which we precisely
describe. The normalization consists of accelerating time by a factor
$\log(1/{\lambda})$ and of compressing space by a factor
${\lambda}\log(1/{\lambda})$. The limit process is quite simple: it can be
built using a graphical construction and can be perfectly simulated. Finally,
we derive some asymptotic estimates (when ${\lambda}\to0$) for the cluster-size
distribution of the forest fire process.


title:
Nonperturbative calculation of the anomalous magnetic moment in the
  Yukawa model

abstract:
  Within the covariant formulation of light-front dynamics, we calculate the
state vector of a fermion coupled to identical scalar bosons (the Yukawa
model). The state vector is decomposed in Fock sectors and we consider the
first three ones: a single fermion, a fermion coupled to one boson, and a
fermion coupled to two bosons. This last three-body sector generates nontrivial
and nonperturbative contributions to the state vector, and these contributions
are calculated with no approximations. The divergences of the amplitudes are
regularized using Pauli-Villars fermion and boson fields. Physical observables
can be unambiguously deduced using a systematic renormalization scheme we
developed. This renormalization scheme is a necessary condition in order to
avoid uncancelled divergences when Fock space is truncated. As an example, we
present preliminary numerical results for the anomalous magnetic moment of a
fermion in the Yukawa model.


title: Infrared stability of quarkyonic matter with the 1/p^4 confinement

abstract:
  We demonstrate an exact cancellation of the infrared divergences in the
color-singlet quarkyonic matter with the 1/p^4 Coulomb-like confining
interaction both in the chiral symmetry broken and restored regimes.


title:
Determination of the biquaternion divisors of zero, including the
  idempotents and nilpotents

abstract:
  The biquaternion (complexified quaternion) algebra contains idempotents
(elements whose square remains unchanged) and nilpotents (elements whose square
vanishes). It also contains divisors of zero (elements with vanishing norm).
The idempotents and nilpotents are subsets of the divisors of zero. These facts
have been reported in the literature, but remain obscure through not being
gathered together using modern notation and terminology. Explicit formulae for
finding all the idempotents, nilpotents and divisors of zero appear not to be
available in the literature, and we rectify this with the present paper. Using
several different representations for biquaternions, we present simple formulae
for the idempotents, nilpotents and divisors of zero, and we show that the
complex components of a biquaternion divisor of zero must have a sum of squares
that vanishes, and that this condition is equivalent to two conditions on the
inner product of the real and imaginary parts of the biquaternion, and the
equality of the norms of the real and imaginary parts. We give numerical
examples of nilpotents, idempotents and other divisors of zero. Finally, we
conclude with a statement about the composition of the set of biquaternion
divisors of zero, and its subsets, the idempotents and the nilpotents.


title:
Relativistic Hartree-Fock-Bogoliubov theory with Density Dependent
  Meson-Nucleon Couplings

abstract:
  Relativistic Hartree-Fock-Bogoliubov (RHFB) theory with density-dependent
meson-nucleon couplings is presented. The integro-differential RHFB equations
are solved by expanding the different components of the quasi-particle spinors
in the complete set of eigen-solutions of the Dirac equations with Woods-Saxon
potentials. Using the finite-range Gogny force D1S as an effective interaction
in the pairing channel, systematic RHFB calculations are performed for Sn
isotopes and N=82 isotones. It is demonstrated that an appropriate description
of both mean field and pairing effects can be obtained within RHFB theory with
finite range Gogny pairing forces. Better systematics are also found in the
regions from the stable to the neutron-rich side with the inclusion of Fock
terms, especially in the presence of $\rho$-tensor couplings.


title: Normal forms for almost non-integrable CR structures

abstract:
  We propose two constructions extending the Chern-Moser normal form to
non-integrable Levi-nondegenerate (hypersurface type) almost CR structures. One
of them translates the Chern-Moser normalization into pure intrinsic setting,
whereas the other directly extends the (extrinsic) Chern-Moser normal form by
allowing non-CR embeddings that are in some sense "maximally CR". One of the
main differences with the classical integrable case is the presence of the
non-integrability tensor at the same order as the Levi form, making impossible
a good quadric approximation - a key tool in the Chern-Moser theory. Partial
normal forms are obtained for general almost CR structures of any CR
codimension, in particular, for almost-complex structures. Applications are
given to the equivalence problem and the Lie group structure of the group of
all CR-diffeomorphisms.


title: Nuclear Track Detectors. Searches for Exotic Particles

abstract:
  We used Nuclear Track Detectors (NTD) CR39 and Makrofol for many purposes: i)
Exposures at the SPS and at lower energy accelerator heavy ion beams for
calibration purposes and for fragmentation studies. ii) Searches for GUT and
Intermediate Mass Magnetic Monopoles (IMM), nuclearites, Q-balls and
strangelets in the cosmic radiation. The MACRO experiment in the Gran Sasso
underground lab, with ~1000 m^2 of CR39 detectors (plus scintillators and
streamer tubes), established an upper limit for superheavy GUT poles at the
level of 1.4x10^-16 cm^-2 s^-1 sr^-1 for 4x10^-5 <beta<1. The SLIM experiment
at the high altitude Chacaltaya lab (5230 m a.s.l.), using 427 m^2 of CR39
detectors exposed for 4.22 y, gave an upper limit for IMMs of ~1.3x10^-15 cm^-2
s^-1 sr^-1. The experiments yielded interesting upper limits also on the fluxes
of the other mentioned exotic particles. iii) Environmental studies, radiation
monitoring, neutron dosimetry.


title: Spectral rigidity of vehicular streams (Random Matrix Theory approach)

abstract:
  Using the methods originally developed for Random Matrix Theory we derive an
exact mathematical formula for number variance (introduced in [4]) describing a
rigidity of particle ensembles with power-law repulsion. The resulting relation
is consequently compared with the relevant statistics of the single-vehicle
data measured on the Dutch freeway A9. The detected value of an inverse
temperature, which can be identified as a coefficient of a mental strain of car
drivers, is then discussed in detail with the respect to the traffic density
and flow.


title: A note on the separability index

abstract:
  In discriminating between objects from different classes, the more separable
these classes are the less computationally expensive and complex a classifier
can be used. One thus seeks a measure that can quickly capture this
separability concept between classes whilst having an intuitive interpretation
on what it is quantifying. A previously proposed separability measure, the
separability index (SI) has been shown to intuitively capture the class
separability property very well. This short note highlights the limitations of
this measure and proposes a slight variation to it by combining it with another
form of separability measure that captures a quantity not covered by the
Separability Index.


title:
The CMS RPC gas gain monitoring system: an overview and preliminary
  results

abstract:
  The status of the CMS RPC Gas Gain Monitoring (GGM) system developed at the
Frascati Laboratory of INFN (Istituto Nazionale di Fisica Nucleare) is reported
on. The GGM system is a cosmic ray telescope based on small RPC detectors
operated with the same gas mixture used by the CMS RPC system. The GGM gain and
efficiency are continuously monitored on-line, thus providing a fast and
accurate determination of any shift in working point conditions. The
construction details and the first result of GGM commissioning are described.


title:
Tunnelling magnetoresistance anomalies of a Coulomb blockaded quantum
  dot

abstract:
  We consider quantum transport and tunneling magnetoresistance (TMR) through
an interacting quantum dot in the Coulomb blockade regime, attached to
ferromagnetic leads. We show that there exist two kinds of anomalies of TMR,
which have different origin. One type, associated with TMR sign change and
appearing at conductance resonances, is of single particle origin. The second
type, inducing a pronounced increase of TMR value far beyond 100%, is caused by
electron correlations. It is manifested in-between Coulomb blockade conductance
peaks. Both types of anomalies are discussed for zero and finite bias and their
robustness to the temperature increase is also demonstrated. The results are
presented in the context of recent experiments on semiconductor quantum dots in
which similar features of TMR have been observed.


title:
Analytical Blowup Solutions to the 2-dimensional Isothermal
  Euler-Poisson Equations of Gaseous Stars

abstract:
  We study the Euler-Poisson equations of describing the evolution of the
gaseous star in astrophysics. Firstly, we construct a family of analytical
blowup solutions for the isothermal case in R^2. Furthermore the blowup rate of
the above solutions is also studied and some remarks about the applicability of
such solutions to the Navier-Stokes-Poisson equations and the drift-diffusion
model in semiconductors are included. Finally, for the isothermal case, the
result of Makino and Perthame for the tame solutions is extended to show that
the life span of such solutions must be finite if the initial data is with
compact support.


title: Photon generation through decoherence in cavity QED: analytical analysis

abstract:
  The Rabi Hamiltonian describes the interaction between a two-level atom and a
single mode of the quantized electromagnetic field. When the system is subject
to the Markovian atomic dephasing reservoir, the anti-rotating term leads to
the photon generation from vacuum. In the presence of Markovian damping
reservoirs, the asymptotic mean photon number is higher than the thermal photon
number expected in the absence of the anti-rotating term. We obtain approximate
analytical expressions in the asymptotic regime for the photon creation rate in
the pure dephasing case and the mean photon number and the atomic population
inversion in the general case. Our analytical results are valid in the small
mean photon number limit and they were tested by numerical analyses.


title: Precision tests of the SM with leptonic and semileptonic kaon decays

abstract:
  This paper presents the analysis of leptonic and semileptonic kaon decays
data done by the FlaviaNet Kaon Working group. Data include all recent results
by BNL-E865, KLOE, KTeV, ISTRA+, and NA48. Experimental results are critically
reviewed and combined, taking into account theoretical (both analytical and
numerical) constraints on the semileptonic kaon form factors. We report on a
very accurate determination of V_{us} as well as on many other tests of the SM
which can be performed with leptonic and semileptonic K decays.


title:
Dynamical density functional theory for molecular and colloidal fluids:
  a microscopic approach to fluid mechanics

abstract:
  In recent years, a number of dynamical density functional theories (DDFTs)
have been developed for describing the dynamics of the one-body density of both
colloidal and atomic fluids. In the colloidal case, the particles are assumed
to have stochastic equations of motion and theories exist for both the case
when the particle motion is over-damped and also in the regime where inertial
effects are relevant. In this paper we extend the theory and explore the
connections between the microscopic DDFT and the equations of motion from
continuum fluid mechanics. In particular, starting from the Kramers equation
which governs the dynamics of the phase space probability distribution function
for the system, we show that one may obtain an approximate DDFT that is a
generalisation of the Euler equation. This DDFT is capable of describing the
dynamics of the fluid density profile down to the scale of the individual
particles. As with previous DDFTs, the dynamical equations require as input the
Helmholtz free energy functional from equilibrium density functional theory
(DFT). For an equilibrium system, the theory predicts the same fluid one-body
density profile as one would obtain from DFT. Making further approximations, we
show that the theory may be used to obtain the mode coupling theory that is
widely used for describing the transition from a liquid to a glassy state.


title: Effective description of squark interactions

abstract:
  We propose an effective description of squark interactions with
charginos/neutralinos. We recompute the strong corrections to squark partial
decay widths, and compare the full one-loop computation with the effective
description. The effective description includes the effective Yukawa couplings,
and another logarithmic term which encodes the supersymmetry-breaking. The
proposed effective couplings reproduce correctly the radiative-corrected
partial decay widths of the squark decays into charginos and neutralinos in all
relevant regions of the parameter space.


title: Reentrant spin glass state in Mn doped Ni2MnSn shape memory alloy

abstract:
  The ground state properties of the ferromagnetic shape memory alloy of
nominal composition Ni2Mn1.36Sn0.64 have been studied by dc magnetization and
ac susceptibility measurements. Like few other Ni-Mn based alloys, this sample
exhibits exchange bias phenomenon. The observed exchange bias pinning was found
to originate right from the temperature where a step-like anomaly is present in
the zero-field-cooled magnetization data. The ac susceptibility study indicates
the onset of spin glass freezing near this step-like anomaly with clear
frequency shift. The sample can be identified as a reentrant spin glass with
both ferromagnetic and glassy phases coexisting together at low temperature at
least in the field-cooled state. The result provides us an comprehensive view
to identify the magnetic character of various Ni-Mn-based shape memory alloys
with competing magnetic interactions.


title: Manifestations of topological effects in graphene

abstract:
  Graphene is a monoatomic layer of graphite with Carbon atoms arranged in a
two dimensional honeycomb lattice configuration. It has been known for more
than sixty years that the electronic structure of graphene can be modelled by
two-dimensional massless relativistic fermions. This property gives rise to
numerous applications, both in applied sciences and in theoretical physics.
Electronic circuits made out of graphene could take advantage of its high
electron mobility that is witnessed even at room temperature. In the
theoretical domain the Dirac-like behavior of graphene can simulate high energy
effects, such as the relativistic Klein paradox. Even more surprisingly,
topological effects can be encoded in graphene such as the generation of
vortices, charge fractionalization and the emergence of anyons. The impact of
the topological effects on graphene's electronic properties can be elegantly
described by the Atiyah-Singer index theorem. Here we present a pedagogical
encounter of this theorem and review its various applications to graphene. A
direct consequence of the index theorem is charge fractionalization that is
usually known from the fractional quantum Hall effect. The charge
fractionalization gives rise to the exciting possibility of realizing graphene
based anyons that unlike bosons or fermions exhibit fractional statistics.
Besides being of theoretical interest, anyons are a strong candidate for
performing error free quantum information processing.

categories: cond-mat.mes-hall cond-mat.str-el hep-th quant-ph


title: Phase-space analysis of interacting phantom cosmology

abstract:
  We perform a detailed phase-space analysis of various phantom cosmological
models, where the dark energy sector interacts with the dark matter one. We
examine whether there exist late-time scaling attractors, corresponding to an
accelerating universe and possessing dark energy and dark matter densities of
the same order. We find that all the examined models, although accepting stable
late-time accelerated solutions, cannot alleviate the coincidence problem,
unless one imposes a form of fine-tuning in the model parameters. It seems that
interacting phantom cosmology cannot fulfill the basic requirement that led to
its construction.


title: Sensor Based on Extending the Concept of Fidelity to Classical Waves

abstract:
  We propose and demonstrate a remote sensor scheme by applying the quantum
mechanical concept of fidelity loss to classical waves. The sensor makes
explicit use of time-reversal invariance and spatial reciprocity in a wave
chaotic system to sensitively and remotely measure the presence of small
perturbations. The loss of fidelity is measured through a classical wave-analog
of the Loschmidt echo by employing a single-channel time-reversal mirror to
rebroadcast a probe signal into the perturbed system. We also introduce the use
of exponential amplification of the probe signal to partially overcome the
effects of propagation losses and to vary the sensitivity.


title: An analysis of a random algorithm for estimating all the matchings

abstract:
  Counting the number of all the matchings on a bipartite graph has been
transformed into calculating the permanent of a matrix obtained from the
extended bipartite graph by Yan Huo, and Rasmussen presents a simple approach
(RM) to approximate the permanent, which just yields a critical ratio
O($n\omega(n)$) for almost all the 0-1 matrices, provided it's a simple
promising practical way to compute this #P-complete problem. In this paper, the
performance of this method will be shown when it's applied to compute all the
matchings based on that transformation. The critical ratio will be proved to be
very large with a certain probability, owning an increasing factor larger than
any polynomial of $n$ even in the sense for almost all the 0-1 matrices. Hence,
RM fails to work well when counting all the matchings via computing the
permanent of the matrix. In other words, we must carefully utilize the known
methods of estimating the permanent to count all the matchings through that
transformation.


title:
Multiplicative scale uncertainties in the unified approach for
  constructing confidence intervals

abstract:
  We have investigated how uncertainties in the estimation of the detection
efficiency affect the 90% confidence intervals in the unified approach for
constructing confidence intervals. The study has been conducted for experiments
where the number of detected events is large and can be described by a Gaussian
probability density function. We also assume the detection efficiency has a
Gaussian probability density and study the range of the relative uncertainties
$\sigma_\epsilon$ between 0 and 30%. We find that the confidence intervals
provide proper coverage over a wide signal range and increase smoothly and
continuously from the intervals that ignore scale uncertainties with a
quadratic dependence on $\sigma_\epsilon$.


title: A proof of the rooted tree alternative conjecture

abstract:
  Bonato and Tardif conjectured that the number of isomorphism classes of trees
mutually embeddable with a given tree T is either 1 or infinite. We prove the
analogue of their conjecture for rooted trees. We also discuss the original
conjecture for locally finite trees and state some new conjectures.


title: Promoting cooperation in social dilemmas via simple coevolutionary rules

abstract:
  We study the evolution of cooperation in structured populations within
popular models of social dilemmas, whereby simple coevolutionary rules are
introduced that may enhance players abilities to enforce their strategy on the
opponent. Coevolution thus here refers to an evolutionary process affecting the
teaching activity of players that accompanies the evolution of their
strategies. Particularly, we increase the teaching activity of a player after
it has successfully reproduced, yet we do so depending on the disseminated
strategy. We separately consider coevolution affecting either only the
cooperators or only the defectors, and show that both options promote
cooperation irrespective of the applied game. Opposite to intuitive reasoning,
however, we reveal that the coevolutionary promotion of players spreading
defection is, in the long run, more beneficial for cooperation than the
likewise promotion of cooperators. We explain the contradictory impact of the
two considered coevolutionary rules by examining the differences between
resulting heterogeneities that segregate participating players, and
furthermore, demonstrate that the influential individuals completely determine
the final outcome of the games. Our findings are immune to changes defining the
type of considered social dilemmas and highlight that the heterogeneity of
players, resulting in a positive feedback mechanism, is a fundamental property
promoting cooperation in groups of selfish individuals.


title:
Improved Approximation for the Number of Hamiltonian Cycles in Dense
  Digraphs

abstract:
  We propose an improved algorithm for counting the number of Hamiltonian
cycles in a directed graph. The basic idea of the method is sequential
acceptance/rejection, which is successfully used in approximating the number of
perfect matchings in dense bipartite graphs. As a consequence, a new bound on
the number of Hamiltonian cycles in a directed graph is proved, by using the
ratio of the number of 1-factors. Based on this bound, we prove that our
algorithm runs in expected time of $O(n^{8.5})$ for dense problems. This
improves the Markov chain method, the most powerful existing method, a factor
of at least $n^{4.5}(\log n)^{4}$ in running time. This class of dense problems
is shown to be nontrivial in counting, in the sense that it is $#$P-Complete.


title: A Unified Approach of Parameter Estimation

abstract:
  We introduce a new distance and we use it to parameter estimation purposes.
We observe how it operates and we use in its place the usual methods of
estimation which we call the methods of the new approach. We realize that we
obtain a discretization of the continuous case. Moreover, when it is necessary
to consider truncated data nothing is changed in computations.


title: Traversal of pulses through negative ($\varepsilon$, $\mu$) materials

abstract:
  We study the traversal times of electromagnetic pulses across dispersive
media with negative dielectric permittivity ($\varepsilon$) and magnetic
permeability ($\mu$) parameters. First we investigate the transport of optical
pulses through an electrical plasma and a negative refractive index medium
(NRM) of infinite and semi-infinite extents where no resonant effects come into
play. The total delay time of the pulse constitutes of the group delay time and
the reshaping delay time as analyzed by Peatross et al \cite{peatross}. For
evanescent waves, even with broadband width, the total delay time is negative
for an infinite medium whereas it is positive for the semi-infinite case.
Evidence of the Hartman effect is seen for small propagation distance compared
to the free space pulse length. The reshaping delay mostly dominates the total
delay time in NRM whereas it vanishes when $\varepsilon(\omega)=\mu(\omega)$.
  Next we present results on the propagation times through a dispersive slab.
While both large bandwidth and large dissipation have similar effects in
smoothening out the resonant features that appear due to Fabry-P\'{e}rot
resonances, large dissipation can result in very small or even negative
traversal times near the resonant frequencies. We investigate the traversal and
the Wigner delay times for obliquely incident pulses. The coupling of
evanescent waves to slab plasmon polariton modes results in large traversal
times at the resonant conditions. We also find that the group velocity mainly
contributes to the delay time for pulse propagating across a slab with
refractive index (n) = -1. The traversal times are positive and subluminal for
pulses with sufficiently large bandwidths.


title: Emerge-Sort: Converging to Ordered Sequences by Simple Local Operators

abstract:
  In this paper we examine sorting on the assumption that we do not know in
advance which way to sort a sequence of numbers and we set at work simple local
comparison and swap operators whose repeating application ends up in sorted
sequences. These are the basic elements of Emerge-Sort, our approach to
self-organizing sorting, which we then validate experimentally across a range
of samples. Observing an O(n2) run-time behaviour, we note that the n/logn
delay coefficient that differentiates Emerge-Sort from the classical comparison
based algorithms is an instantiation of the price of anarchy we pay for not
imposing a sorting order and for letting that order emerge through the local
interactions.


title: Inclusive diffraction and factorisation at HERA

abstract:
  In this article, recent measurements of diffraction in deep inelastic
scattering are presented along with QCD fits to extract the partonic structure
of the exchange. These so-called diffractive parton density functions can then
be used in predictions for other processes to test factorisation in
diffraction. This is an important verification of QCD and has significance for
predicting exotic signals such as diffractive Higgs production at the LHC.


title: Magnetism of frustrated regular networks

abstract:
  We consider a regular random network where each node has exactly three
neighbours. Ising spins at the network nodes interact antiferromagnetically
along the links. The clustering coefficient $C$ is tuned from zero to 1/3 by
adding new links. At the same time, the density of geometrically frustrated
links increases. We calculate the magnetic specific heat, the spin
susceptibility and the Edwards-Anderson order parameter $q$ by means of the
heat-bath Monte Carlo simulations. The aim is the transition temperature $T_x$
dependence on the clustering coefficient $C$. The results are compared with the
predictions of the Bethe approximation. At C=0, the network is bipartite and
the low temperature phase is antiferromagnetic. When $C$ increases, the
critical temperature falls down towards the values which are close to the
theoretical predictions for the spin-glass phase.


title:
CP violation in associated production of a charged Higgs boson and a top
  quark at the LHC

abstract:
  We study effects of CP violation in an associated production of a charged
Higgs boson and a top quark at the LHC: $pp \to tH^\pm +X$. We calculate the CP
violating asymmetry between the total cross section for $H^+$ and $H^-$
production at next-to-leading order in the MSSM, and perform a detailed
numerical analysis. In the production only the asymmetry is of the order of
20%. The asymmetry in the production and any subsequent decay of an on-shell
charged Higgs boson is to a good approximation the sum of the asymmetry in the
production and the asymmetry in the decay. We consider subsequent decays of
$H^\pm $ to $tb$, $\nu_\tau \tau^\pm$ and $Wh^0$. In the case of subsequent
$H^\pm \to tb$ decay, the $W^\pm - H^\pm$ self energy contributions from the
production and the decay cancel. However, the remaining effect, mainly due to
CP violating box graphs with gluino can go up to $\sim 13$%.


title: Real and imaginary-time quarkonium correlators in a hot plasma

abstract:
  The possibility of describing the behavior of a $Q\overline{Q}$ pair in a hot
plasma in terms of an effective potential is investigated. It is shown that as
long as medium effects can be embodied in a gaussian action, like in the QED
case, the $Q\overline{Q}$ propagator obeys a closed temporal evolution equation
whose large-time behavior is governed by an effective potential. The latter,
beside screening, displays also an imaginary part related to collisions.


title: Interplay between superconductivity and magnetism in K-doped EuFe2As2

abstract:
  Superconductivity is found in 50% K-doped EuFe2As2 sample below 33 K. Our
results of electrical resistivity, magnetic susceptibility and 57Fe and 151Eu
Mossbauer spectroscopy provide clear evidence that the ordering of the Fe
moments observed at 190 K in undoped EuFe2As2 is completely suppressed in our
50% K doped sample, thus there is no coexistence between the Fe magnetic order
and the superconducting state. However, short range ordering of the Eu moments
is coexisting with the superconducting state below 15 K. A bump in the
susceptibility well below Tc as well as a slight broadening of the Fe Mossbauer
line below 15 K evidence an interplay between the Eu magnetism and the
superconducting state.


title: Quasar optical variability: searching for interband time delays

abstract:
  Aims. The main purpose of this paper is to study time delays between the
light variations in different wavebands for a sample of quasars. Measuring a
reliable time delay for a large number of quasars may help constraint the
models of their central engines. The standard accretion disk irradiation model
predicts a delay of the longer wavelengths behind the shorter ones, a delay
that depends on the fundamental quasar parameters. Since the black hole masses
and the accretion rates are approximately known for the sample we use, one can
compare the observed time delays with the expected ones.
  Methods. We applied the interpolation cross-correlation function (ICCF)
method to the Giveon et al. sample of 42 quasars, monitored in two (B and R)
colors, to find the time lags represented by the ICCF peaks. Different tests
were performed to assess the influence of photometric errors, sampling, etc.,
on the final result.
  Results. We found that most of the objects show a delay in the red light
curve behind the blue one (a positive lag), which on average for the sample is
about +4 days (+3 for the median), although the scatter is significant. These
results are broadly consistent with the reprocessing model, especially for the
well-sampled objects. The normalized time-lag deviations do not seem to
correlate significantly with other quasar properties, including optical, radio,
or X-ray measurables. On the other hand, many objects show a clear negative
lag, which, if real, may have important consequences for the variability
models.


title: Saddle-splay modulus of a particle-laden fluid interface

abstract:
  The scaled-particle theory equation of state for the two-dimensional
hard-disk fluid on a curved surface is proposed and used to determine the
saddle-splay modulus of a particle-laden fluid interface. The resulting
contribution to saddle-splay modulus, which is caused by thermal motion of the
adsorbed particles, is comparable in magnitude with the saddle-splay modulus of
a simple fluid interface.


title: Algebraic A-hypergeometric Functions

abstract:
  We formulate and prove a combinatorial criterion to decide if an
A-hypergeometric system of differential equations has a full set of algebraic
solutions or not. This criterion generalises the so-called interlacing
criterion in the case of hypergeometric functions of one variable.


title: Katz's middle convolution and Yokoyama's extending operation

abstract:
  We give a concrete relation between Katz's middle convolution and Yokoyama's
extension and show the equivalence of both algorithms using these operations
for the reduction of Fuchsian systems.


title:
Slave fermion approach to the metallic phase in large $U_d$ high-T$_c$
  cuprates

abstract:
  Atomic repulsion $U_d$ on the Cu site in high T$_c$ cuprates is large but,
surprisingly, some important properties are consistent with moderate couplings.
The time dependent perturbation theory with slave particles is therefore
formulated in the $U_d\to\infty$ limit for the metallic phase in the physically
relevant regime of the three-band Emery model. The basic theory possesses the
local gauge invariance asymptotically but its convergence is fast when the
average occupation of the Cu-site is small. The leading orders exhibit the band
narrowing and the dynamic Cu/O$_2$ charge transfer disorder. The effective
local repulsion between particles on oxygen sites is shown to be moderate in
the physical regime under consideration. It enhances the coherent
incommensurate SDW correlations. The latter compete with the Cu/O$_2$ charge
transfer disorder, in agreement with basic observations in high T$_c$ cuprates.


title:
Multiple temperature scales of the periodic Anderson model: the slave
  bosons approach

abstract:
  The thermodynamic and transport properties of intermetallic compounds with
Ce, Eu, and Yb ions are discussed using the periodic Anderson model with an
infinite correlation between $f$ electrons. The slave boson solution of the
periodic model shows that the Fermi liquid scale T$_0$ and the Kondo scale
T$_K$ depend on the shape of the conduction electrons density of states ($c$
DOS) in the vicinity of the chemical potential, that the details of the band
structure determine the ratio T$_0$/T$_K$, and that the crossover between the
high- and low-temperature regimes in ordered compounds is system-dependent.
  A sharp peak in the $c$ DOS yields T$_0 \ll$T$_K$ and explains the 'slow
crossover' observed in YbAl$_3$ or YbMgCu$_4$. A minimum in the $c$ DOS yields
T$_0 \gg$T$_K$, which leads to the abrupt transition between the high- and
low-temperature regimes in YbInCu$_4$. In the case of CeCu$_2$Ge$_2$ and
CeCu$_2$Si$_2$, where T$_0 \simeq T_K$, the slave boson solution explains the
pressure experiments which reveal sharp peaks in the T$^2$ coefficient of the
electrical resistance, $A=\rho(T)/T^2$, and the residual resistance. These
peaks are due to the change in the degeneracy of the $f$ states induced by the
applied pressure.
  We show that the low-temperature response of the periodic Anderson model can
be enhanced (or reduced) with respect to the predictions based on the
single-impurity models that give the same high-temperature behavior.


title: A simplicial model for proper homotopy types

abstract:
  The singular simplicial set Sing(X) of a space X completely captures its weak
homotopy type. We introduce a category of_controlled sets_, yielding
_simplicial controlled sets_, such that one can functorially produce a singular
simplicial controlled set CSing(MaxCtl(X)) from a locally compact X. We then
argue that this CSing(MaxCtl(X)) captures the (weak)_proper_ homotopy type of
X. Moreover, our techniques strictly generalize the classical simplicial
situation: e.g., one obtains, in a unified way, singular homology with compact
supports and (Borel-Moore) singular homology with locally finite supports, as
well as the corresponding cohomologies.


title:
On minimal actions of finite simple groups on homology spheres and
  Euclidean spaces

abstract:
  We consider the following problem: for which classes of finite groups, and in
particular finite simple groups, does the minimal dimension of a faithful,
smooth action on a homology sphere coincide with the minimal dimension of a
faithful, linear action on a sphere? We prove that the two minimal dimensions
coincide for the linear fractional groups PSL(2,p) as well as for various
classes of alternating and symmetric groups. We prove analogous results also
for actions on Euclidean spaces.


title:
On the Vertex Operators of the Elliptic Quantum Algebra
  $U_{q,p}(\widehat{sl_2})_{k}$}

abstract:
  A realization of the elliptic quantum algebra $U_{q,p}(\widehat{sl_2})$ for
any given level $k$ is constructed in terms of three free boson fields and
their accompanying twisted partners. It can be viewed as the elliptic
deformation of Wakimoto realization. Two screening currents are constructed;
they commute or anti-commute with $U_{q,p}(\widehat{sl_2})$ modulo total
q-differences. The free fields realization for two types vertex operators
nominated as the type $I$ and the type $II$ vertex operators are presented. The
twisted version of the two types vertex operators are also obtained. They all
play crucial roles in calculating correlation functions.


title:
Evidence for two-gap nodeless superconductivity in
  SmFeAsO$_{0.8}$F$_{0.2}$ from point-contact Andreev-reflection spectroscopy

abstract:
  Point-contact Andreev-reflection measurements were performed in
SmFeAsO_{0.8}F_{0.2} polycrystals with T_c \simeq 53 K. The experimental
conductance curves reproducibly exhibit peaks around \pm 6 mV and shoulders at
V \sim 16-20 mV, indicating the presence of two nodeless superconducting gaps.
While the single-band Blonder-Tinkham-Klapwijk fit can only reproduce a small
central portion of the conductance curve, the two-gap one accounts remarkably
well for the shape of the whole experimental dI/dV. The fits of the normalized
curves give Delta_1(0) = 6.15 \pm 0.45 meV and Delta_2(0) = 18 \pm 3 meV. Both
gaps close at the same temperature and follow a BCS-like behavior.


title:
Statistics of temperature fluctuations in an electron system out of
  equilibrium

abstract:
  We study the statistics of the fluctuating electron temperature in a metallic
island coupled to reservoirs via resistive contacts and driven out of
equilibrium by either a temperature or voltage difference between the
reservoirs. The fluctuations of temperature are well-defined provided that the
energy relaxation rate inside the island exceeds the rate of energy exchange
with the reservoirs. We quantify these fluctuations in the regime beyond the
Gaussian approximation and elucidate their dependence on the nature of the
electronic contacts.


title:
Time-resolved X-ray microscopy of nanoparticle aggregates under
  oscillatory shear

abstract:
  Of all current detection techniques with nanometer resolution, only X-ray
microscopy allows imaging nanoparticles in suspension. Can it also be used to
investigate structural dynamics? When studying response to mechanical stimuli,
the challenge lies in applying them with precision comparable to spatial
resolution. In the first shear experiments performed in an X-ray microscope, we
accomplished this by inserting a piezo actuator driven shear cell into the
focal plane of a scanning transmission X-ray microscope (STXM). Thus
shear-induced reorganization of magnetite nanoparticle aggregates could be
demonstrated in suspension. As X-ray microscopy proves suitable for studying
structural change, new prospects open up in physics at small length scales.


title: Confinement in Polyakov Gauge

abstract:
  We approach the non-perturbative regime in finite temperature QCD within a
formulation in Polyakov gauge. The construction is based on a complete gauge
fixing. Correlation functions are then computed from Wilsonian renormalisation
group flows. First results for the confinement-deconfinement phase transition
for SU(2) are presented. Within a simple approximation we obtain a second order
phase transition within the Ising universality class. The critical temperature
is computed as T_c = 305 MeV.


title:
A new scheme to calculate the exchange tensor and its application to
  diluted magnetic semiconductors

abstract:
  A new scheme to calculate the exchange tensor
$\underline{\underline{J}}_{ij}$ describing in a phenomenological way the
anisotropic exchange coupling of two moments in a magnetically ordered system
is presented. The ab-initio approach is based on spin-polarised relativistic
multiple-scattering theory within the framework of spin-density functional
theory. The scheme is applied to ferromagnetic CrTe as well as the diluted
magnetic semiconductor (DMS) system Ga$_{1-x}$Mn$_{x}$As. In the later case the
results show that there is a noticeable anisotropy in the exchange coupling
present, although not as pronounced as suggested in recent theoretical
investigations.


title: Sobolev spaces on multiple cones

abstract:
  The purpose of this note is to discuss how various Sobolev spaces defined on
multiple cones behave with respect to density of smooth functions,
interpolation and extension/restriction to/from $\RR^n$. The analysis
interestingly combines use of Poincar\'e inequalities and of some Hardy type
inequalities.


title:
The elliptic quantum algebra $U_{q,p}(\hat{sl_N})$ and its vertex
  operators

abstract:
  We construct a realization of the elliptic quantum algebra
$U_{q,p}(\hat{sl_N})$ for any given level $k$ in terms of free boson fields and
their twisted partners. It can be considered as the elliptic deformation of the
Wakimoto realization of the quantum affine algebra $U_{q}(\hat{sl_N})$. We also
construct a family of screening currents, which commute with the currents of
$U_{q,p}(\hat{sl_N})$ up to total q-differences. And we give explicit twisted
expressions for the type $I$ and the type $II$ vertex operators of
$U_{q,p}(\hat{sl_N})$ by twisting the known results of the type $I$ vertex
operators of the quantum affine algebra $U_{q}(\hat{sl_N})$ and the new results
of the type $II$ vertex operators of $U_{q}(\hat{sl_N})$ we obtained in this
paper.


title:
The Invariant Set Postulate: A New Geometric Framework for the
  Foundations of Quantum Theory and the Role Played by Gravity

abstract:
  A new law of physics is proposed, defined on the cosmological scale but with
significant implications for the microscale. Motivated by nonlinear dynamical
systems theory and black-hole thermodynamics, the Invariant Set Postulate
proposes that cosmological states of physical reality belong to a
non-computable fractal state-space geometry I, invariant under the action of
some subordinate deterministic causal dynamics. An exploratory analysis is made
of a possible causal realistic framework for quantum physics, based on key
properties of I. For example, sparseness is used to relate generic
counterfactual states to points not lying on I, thus providing a geometric
basis for the essential contextuality of quantum physics and the role of the
abstract Hilbert Space in quantum theory. Also, self-similarity, described in a
symbolic setting, provides a possible "realistic" perspective on the essential
role of complex numbers and quaternions in quantum theory. A new interpretation
is given to the standard "mysteries" of quantum theory: superposition,
measurement, nonlocality, emergence of classicality and so on. It is proposed
that heterogeneities in the fractal geometry of I are manifestations of the
phenomenon of gravity. Since quantum theory is inherently blind to the
existence of such state-space geometries, the analysis here suggests that
attempts to formulate unified theories of physics within a conventional
quantum-theoretic framework are misguided, and that a successful quantum theory
of gravity should unify the causal non-Euclidean geometry of space time with
the atemporal fractal geometry of state space.


title:
XMM-Newton detects a relativistically broadened iron line in the
  spectrum of the ms X-ray pulsar SAX J1808.4-3658

abstract:
  We report on a 63-ks long XMM-Newton observation of the accreting millisecond
pulsar SAX J1808.4-3658 during the latest X-ray outburst which started on
September 21st 2008. The pn spectrum shows a highly significant emission line
in the energy band where the iron K-alpha line is expected, and which we
identify as emission from neutral (or mildly ionized) iron. The line profile
appears to be quite broad (more than 1 keV FWHM) and asymmetric; the most
probable explanation for this profile is Doppler and relativistic broadening
from the inner accretion disc. From a fit with a diskline profile we find an
inner radius of the disc of 8.7^(+3.7)_(-2.7) R_g, corresponding to
18.0^(+7.6)_(-5.6) km for a 1.4 Msun neutron star. The disc therefore appears
truncated inside the corotation radius (31 km for SAX J1808.4-3658) in
agreement with the fact that the source was still showing pulsations during the
XMM-Newton observation.


title:
Results from the First Science Run of the ZEPLIN-III Dark Matter Search
  Experiment

abstract:
  The ZEPLIN-III experiment in the Palmer Underground Laboratory at Boulby uses
a 12kg two-phase xenon time projection chamber to search for the weakly
interacting massive particles (WIMPs) that may account for the dark matter of
our Galaxy. The detector measures both scintillation and ionisation produced by
radiation interacting in the liquid to differentiate between the nuclear
recoils expected from WIMPs and the electron recoil background signals down to
~10keV nuclear recoil energy. An analysis of 847kg.days of data acquired
between February 27th 2008 and May 20th 2008 has excluded a WIMP-nucleon
elastic scattering spin-independent cross-section above 8.1x10(-8)pb at
55GeV/c2 with a 90% confidence limit. It has also demonstrated that the
two-phase xenon technique is capable of better discrimination between electron
and nuclear recoils at low-energy than previously achieved by other xenon-based
experiments.


title: Superconformal Algebras and Mock Theta Functions

abstract:
  It is known that characters of BPS representations of extended superconformal
algebras do not have good modular properties due to extra singular vectors
coming from the BPS condition. In order to improve their modular properties we
apply the method of Zwegers which has recently been developed to analyze
modular properties of mock theta functions. We consider the case of N=4
superconformal algebra at general levels and obtain the decomposition of
characters of BPS representations into a sum of simple Jacobi forms and an
infinite series of non-BPS representations.
  We apply our method to study elliptic genera of hyper-Kahler manifolds in
higher dimensions. In particular we determine the elliptic genera in the case
of complex 4 dimensions of the Hilbert scheme of points on K3 surfaces K^{[2]}
and complex tori A^{[[3]]}.


title: Smoothness in Relative Geometry

abstract:
  In \cite{tva}, Bertrand Toen and Michel Vaquie defined a scheme theory for a
closed monoidal category $(C,\otimes,1)$. In this article, we define a notion
of smoothness in this relative (and not necesarilly additive) context which
generalizes the notion of smoothness in the category of rings. This
generalisation consists practically in changing homological finiteness
conditions into homotopical ones using Dold-Kahn correspondance. To do this, we
provide the category $sC$ of simplicial objects in a monoidal category and all
the categories $sA-mod$, $sA-alg$ ($a\in sComm(C)$) with compatible model
structures using the work of Rezk in \cite{r}. We give then a general notions
of smoothness in $sComm(C)$. We prove that this notion is a generalisation of
the notion of smooth morphism in the category of rings and provide some
examples of smooth morphisms in $N-alg$, $Comm(Set)$ and Comm(C).


title:
Numerical study of a flow of regular planar curves that develop
  singularities at finite time

abstract:
  In this paper, we will study the following geometric flow, obtained by
Goldstein and Petrich while considering the evolution of a vortex patch in the
plane under Euler's equations,
  X_t = -k_s n - (1/2) k^2 T, with s being the arc-length parameter and k the
curvature. Perelman and Vega proved that this flow has a one-parameter family
of regular solutions that develop a corner-shaped singularity at finite time.
We will give a method to reproduce numerically the evolution of those
solutions, as well as the formation of the corner, showing several properties
associated to them.


title:
Sympathetically cooled molecular ions: from principles to first
  applications

abstract:
  We review the current status of the field of sympathetically cooled molecular
ions, i.e. the method used for cooling the translational degrees of freedom,
the techniques applied for detection and analysis of the cold trapped ion
ensembles produced as well as first applications. We summarize a few salient
results and point out various possibilities for future developments.


title:
Complex Agent Networks explaining the HIV epidemic among homosexual men
  in Amsterdam

abstract:
  Simulating the evolution of the Human Immunodeficiency Virus (HIV) epidemic
requires a detailed description of the population network, especially for small
populations in which individuals can be represented in detail and accuracy. In
this paper, we introduce the concept of a Complex Agent Network(CAN) to model
the HIV epidemics by combining agent-based modelling and complex networks, in
which agents represent individuals that have sexual interactions. The
applicability of CANs is demonstrated by constructing and executing a detailed
HIV epidemic model for men who have sex with men (MSM) in Amsterdam, including
a distinction between steady and casual relationships. We focus on MSM contacts
because they play an important role in HIV epidemics and have been tracked in
Amsterdam for a long time. Our experiments show good correspondence between the
historical data of the Amsterdam cohort and the simulation results.


title:
Multi-frequency VLBA study of the blazar S5 0716+714 during the active
  state in 2004: I. Inner jet kinematics

abstract:
  We observed the blazar \object{0716+714} with the
  VLBA during its active state in 2003-2004. In this paper we discuss
multi-frequency analysis of the inner jet (first 1 mas) kinematics. The
unprecedentedly dense time sampling allows us to trace jet components without
misidentification and to calculate the component speeds with good accuracy. In
the smooth superluminal jet we were able to identify and track three components
over time moving outwards with relatively high apparent superluminal speeds
(8.5-19.4 $c$), which contradicts the hypothesis of a stationary oscillating
jet in this source. Component ejections occur at a relatively high rate (once
in two months), and they are accompanied by mm-continuum outbursts.
Superluminal jet components move along wiggling trajectories, which is an
indication of actual helical motion. Fast proper motion and rapid decay of the
components suggest that this source should be observed with the VLBI at a rate
of at least once in one or two months in order to trace superluminal jet
components without confusion.


title: Covering space theory for directed topology

abstract:
  The state space of a machine admits the structure of time. For example, the
geometric realization of a precubical set, a generalization of an unlabeled
asynchronous transition system, admits a "local preorder" encoding control
flow. In the case where time does not loop, the "locally preordered" state
space splits into causally distinct components. The set of such components
often gives a computable invariant of machine behavior. In the general case, no
such meaningful partition could exist. However, as we show in this note, the
locally preordered geometric realization of a precubical set admits a "locally
monotone" covering from a state space in which time does not loop. Thus we hope
to extend geometric techniques in static program analysis to looping processes.


title:
Espaces critiques pour le syst\`eme des equations de Navier-Stokes
  incompressibles

abstract:
  In this work, we exhibit abstract conditions on a functional space E who
insure the existence of a global mild solution for small data in E or the
existence of a local mild solution in absence of size constraints for a class
of semi-linear parabolic equations, which contains the incompressible
Navier-Stokes system as a fundamental example. We also give an abstract
criterion toward regularity of the obtained solutions. These conditions, given
in terms of Littlewood-Paley estimates for products of spectrally localized
elements of $E$, are simple to check in all known cases: Lebesgue, Lorents,
Besov, Morrey... spaces. These conditions also apply to non-invariant spaces E
and we give full details in the case of some 2-microlocal spaces. The following
comments did not show on the first version: This article was written around
1998-99 and never published, because at that time, Koch and Tataru announced
their result on well-posedness of Navier-stokes equations with initial data in
$BMO^{-1}$. We believe though that some results and counterexamples here are of
independent interest and we make them available electronically.


title:
Nearby young stars selected by proper motion. I. Four new members of the
  Beta Pictoris moving group from the Tycho-2 catalog

abstract:
  We describe a procedure to identify stars from nearby moving groups and
associations out of catalogs of stars with large proper motions. We show that
from the mean motion vector of a known or suspected moving group, one can
identify additional members of the group based on proper motion data and
photometry in the optical and infrared, with minimal contamination from
background field stars. We demonstrate this technique by conducting a search
for low-mass members of the Beta Pictoris Moving Group in the Tycho-2 catalog.
All known members of the moving group are easily recovered, and a list of 51
possible candidates is generated. Moving group membership is evaluated for 33
candidates based on X-ray flux from ROSAT, Halpha line emission, and radial
velocity measurement from high-resolution infrared spectra obtained at Infrared
Telescope Facility. We confirm three of the candidates to be new members of the
group: TYC 1186-706-1, TYC 7443-1102-1, and TYC 2211-1309-1 which are late-K
and early-M dwarfs 45-60pc from the Sun. We also identify a common proper
motion companion to the known Beta Pictoris Moving Group member TYC
7443-1102-1, at a 26".3 separation; the new companion is associated with the
X-ray source 1RXS J195602.8-320720. We argue that the present technique could
be applied to other large proper motion catalogs to identify most of the
elusive, low-mass members of known nearby moving groups and associations.


title: Dual channel self-oscillating optical magnetometer

abstract:
  We report on a two-channel magnetometer based on nonlinear magneto-optical
rotation in a Cs glass cell with buffer gas. The Cs atoms are optically pumped
and probed by free running diode lasers tuned to the D$_2$ line. A wide
frequency modulation of the pump laser is used to produce both synchronous
Zeeman optical pumping and hyperfine repumping. The magnetometer works in an
unshielded environment and spurious signal from distant magnetic sources is
rejected by means of differential measurement. In this regime the magnetometer
simultaneously gives the magnetic field modulus and the field difference.
  Rejection of the common-mode noise allows for high-resolution magnetometry
with a sensitivity of \pthz{2}. This sensitivity, in conjunction with long-term
stability and a large bandwidth, makes possible to detect water proton
magnetization and its free induction decay in a measurement volume of 5 cm$^3$


title:
HATNet Field G205: Follow-Up Observations of 28 Transiting-Planet
  candidates and Confirmation of the Planet HAT-P-8b

abstract:
  We report the identification of 32 transiting-planet candidates in HATNet
field G205. We describe the procedures that we have used to follow up these
candidates with spectroscopic and photometric observations, and we present a
status report on our interpretation of the 28 candidates for which we have
follow-up observations. Eight are eclipsing binaries with orbital solutions
whose periods are consistent with their photometric ephemerides; two of these
spectroscopic orbits are singled-lined and six are double-lined. For one of the
candidates, a nearby but fainter eclipsing binary proved to be the source for
the HATNet light curve, due to blending in the HATNet images. Four of the
candidates were found to be rotating more rapidly than vsini = 50 km/s and were
not pursued further. Thirteen of the candidates showed no significant velocity
variation at the level of 0.5 to 1.0 km/s . Seven of these were eventually
withdrawn as photometric false alarms based on an independent reanalysis using
more sophisticated tools. Of the remaining six, one was put aside because a
close visual companion proved to be a spectroscopic binary, and two were not
followed up because the host stars were judged to be too large. Two of the
remaining candidates are members of a visual binary, one of which was
previously confirmed as the first HATNet transiting planet, HAT-P-1b. In this
paper we confirm that the last of this set of candidates is also a a transiting
planet, which we designate HAT-P-8b, with mass Mp = 1.52 +/- 0.18/0.16 Mjup,
radius Rp = 1.50 +/- 0.08/0.06 Rjup, and photometric period P = 3.076320 +/-
0.000004 days. HAT-P-8b has an inflated radius for its mass, and a large mass
for its period. The host star is a solar-metallicity F dwarf, with mass M* =
1.28 +/- 0.04 Msun and Rp = 1.58 +/- 0.08/0.06 Rsun.


title: Fluctuation Theorems for Systems under Fokker-Planck dynamics

abstract:
  We study Brownian motion driven with both conservative and nonconservative
external forces. By using the thermodynamic approach of the theory of Brownian
motion we obtain the Fokker-Planck equation and derive expressions for the
Fluctuation Theorem in local equilibrium and in quasi-equilibrium. In local
equilibrium the expressions we obtain coincide with previous results.


title:
Periodic Geodesics and Geometry of Compact Lorentzian Manifolds with a
  Killing Vector Field

abstract:
  We study the geometry and the periodic geodesics of a compact Lorentzian
manifold that has a Killing vector field which is timelike somewhere. Using a
compactness argument for subgroups of the isometry group, we prove the
existence of one timelike non self-intersecting periodic geodesic. If the
Killing vector field is never vanishing, then there are at least two distinct
periodic geodesics; as a special case, compact stationary manifolds have at
least two periodic timelike geodesics. We also discuss some properties of the
topology of such manifolds. In particular, we show that a compact manifold $M$
admits a Lorentzian metric with a never vanishing Killing vector field which is
timelike somewhere if and only if $M$ admits a smooth circle action without
fixed points.


title:
Sensitivity to the cutoff value in the quadratic adaptive
  integrate-and-fire model

abstract:
  The quadratic adaptive integrate-and-fire model (Izhikecih 2003, 2007) is
recognized as very interesting for its computational efficiency and its ability
to reproduce many behaviors observed in cortical neurons. For this reason it is
currently widely used, in particular for large scale simulations of neural
networks. This model emulates the dynamics of the membrane potential of a
neuron together with an adaptation variable. The subthreshold dynamics is
governed by a two-parameter differential equation, and a spike is emitted when
the membrane potential variable reaches a given cutoff value. Subsequently the
membrane potential is reset, and the adaptation variable is added a fixed value
called the spike-triggered adaptation parameter. We show in this note that when
the system does not converge to an equilibrium point, both variables of the
subthreshold dynamical system blow up in finite time whatever the parameters of
the dynamics. The cutoff is therefore essential for the model to be well
defined and simulated. The divergence of the adaptation variable makes the
system very sensitive to the cutoff: changing this parameter dramatically
changes the spike patterns produced. Furthermore from a computational
viewpoint, the fact that the adaptation variable blows up and the very sharp
slope it has when the spike is emitted implies that the time step of the
numerical simulation needs to be very small (or adaptive) in order to catch an
accurate value of the adaptation at the time of the spike. It is not the case
for the similar quartic (Touboul 2008) and exponential (Brette and Gerstner
2005) models whose adaptation variable does not blow up in finite time, and
which are therefore very robust to changes in the cutoff value.


title:
Independence Complexes of Cylinders Constructed from Square and
  Hexagonal Grid Graphs

abstract:
  Fendley, Schoutens and van Eerten [Fendley et al., J. Phys. A: Math. Gen., 38
(2005), pp. 315-322] studied the hard square model at negative activity. They
found analytical and numerical evidence that the eigenvalues of the transfer
matrix with periodic boundary were all roots of unity. They also conjectured
that for an m times n square grid, with doubly periodic boundary, the partition
function is equal to 1 when m and n are relatively prime. These conjectures
were later proven by Jonsson [Jonsson, Electronic J. Combin., 13(1) (2006),
R67]. There, it was also noted that the cylindrical case seemed to have
interesting properties when the circumference of the cylinder is odd. In
particular, when 3 is a divisor of both the circumference and the width of the
cylinder minus 1, the partition function is -2. Otherwise, it is equal to 1. In
this paper, we investigate the hard square and hard hexagon models at activity
-1, with single periodic boundary, i.e, cylindrical identifications, using both
topological and combinatorial techniques. We compute the homology groups of the
associated independence complex for small sizes and suggest a matching which,
we believe, with further analysis could help solve the conjecture.


title: Modeling phase behavior for quantifying micro-pervaporation experiments

abstract:
  We present a theoretical model for the evolution of mixture concentrations in
a micro-pervaporation device, similar to those recently presented
experimentally. The described device makes use of the pervaporation of water
through a thin PDMS membrane to build up a solute concentration profile inside
a long microfluidic channel. We simplify the evolution of this profile in
binary mixtures to a one-dimensional model which comprises two
concentration-dependent coefficients. The model then provides a link between
directly accessible experimental observations, such as the widths of dense
phases or their growth velocity, and the underlying chemical potentials and
phenomenological coefficients. It shall thus be useful for quantifying the
thermodynamic and dynamic properties of dilute and dense binary mixtures.


title: CDF Multi-Muon Events and Singlet Extensions of the MSSM

abstract:
  We discuss a generalization of the minimal supersymmetric extension of the
Standard Model in the form of three additional singlet superfields, which would
explain the essential features of the CDF multi-muon events presented recently:
a large production cross section of ~ 100 pb originates from the production of
a CP-odd scalar A with a mass in the 70 - 80 GeV range and a large value of
tan(beta) ~ 40. The CP-odd scalar A decays dominantly into CP-odd and CP-even
scalars a_1 and h_1, which generate decay cascades h_1 -> 2 h_2 -> 4 a_2 -> 8
tau-leptons, and a_1 -> h_1 a_2 with h_1 decaying as above. The decay a_2 ->
tau+ tau- is slow, leading to a lifetime of O(20) ps. The phenomenology of the
model differs from similar scenarios presented before in that one of the two
cascades leads to 10 instead of 8 tau-leptons, and additional production
processes like associate A production with b b-bar pairs are relevant.


title:
Langevin equation with colored noise for constant-temperature molecular
  dynamics simulations

abstract:
  We discuss the use of a Langevin equation with a colored (correlated) noise
to perform constant-temperature molecular dynamics simulations. Since the
equations of motion are linear in nature, it is easy to predict the response of
a Hamiltonian system to such a thermostat and to tune at will the relaxation
time of modes of different frequency. This allows one to optimize the time
needed to thermalize the system and generate independent configurations. We
show how this frequency-dependent response can be exploited to control the
temperature of Car-Parrinello-like dynamics, keeping at low temperature the
electronic degrees of freedom, without affecting the adiabatic separation from
the vibrations of the ions.


title:
Flux transport solar dynamo models, current problems and possible
  solutions

abstract:
  The sunspot solar cycle has been usually explained as the result of a dynamo
process operating in the sun. This is a classical problem in Astrophysics that
until the present is not fully solved. Here we discuss current problems and
limitations with the solar dynamo modeling and their possible solutions using a
kinematic dynamo model within the Babcock-Leighton approximation as a tool. In
particular, we discuss the importance of the turbulent magnetic pumping versus
the meridional flow circulation in the dynamo operation.


title: A Note on Unparticle Decays

abstract:
  The coupling of an unparticle operator O_U to Standard Model particles opens
up the possibility of unparticle decays into standard model fields. We study
this issue by analyzing the pole structure (and spectral function) of the
unparticle propagator, corrected to account for one-loop polarization effects
from virtual SM particles. We find that the propagator of a scalar unparticle
(of scaling dimension 1 < d_U < 2) with a mass gap m_g develops an isolated
pole, m_p^2-i m_p Gamma_p, with m_p^2 < m_g^2 below the unparticle continuum
that extends above m_g (showing that the theory would be unstable without a
mass gap). If that pole lies below the threshold for decay into two standard
model particles the pole corresponds to a stable unparticle state (and its
width Gamma_p is zero). For m_p^2 above threshold the width is non zero and
related to the unparticle decay rate into Standard Model particles. This
picture is valid for any value of d_U in the considered range.


title: Homological mirror symmetry for the genus two curve

abstract:
  Katzarkov has proposed a generalization of Kontsevich's mirror symmetry
conjecture, covering some varieties of general type. We prove a version of this
conjecture in the simplest example, relating the Fukaya category of a genus two
curve to the category of Landau-Ginzburg branes on a certain singular rational
surface.


title:
System size dependence of cluster properties from two-particle angular
  correlations in Cu+Cu and Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV

abstract:
  We present results on two-particle angular correlations in Cu+Cu and Au+Au
collisions at a center of mass energy per nucleon pair of 200 GeV over a broad
range of pseudorapidity ($\eta$) and azimuthal angle ($\phi$) as a function of
collision centrality. The PHOBOS detector at RHIC has a uniquely-large angular
coverage for inclusive charged particles, which allows for the study of
correlations on both long- and short-range scales. A complex two-dimensional
correlation structure in $\Delta \eta$ and $\Delta \phi$ emerges, which is
interpreted in the context of a cluster model. The effective cluster size and
decay width are extracted from the two-particle pseudorapidity correlation
functions. The effective cluster size found in semi-central Cu+Cu and Au+Au
collisions is comparable to that found in proton-proton collisions but a
non-trivial decrease of the size with increasing centrality is observed.
Moreover, a comparison between results from Cu+Cu and Au+Au collisions shows an
interesting scaling of the effective cluster size with the measured fraction of
total cross section (which is related to the ratio of the impact parameter to
the nuclear radius, $b/2R$), suggesting a geometric origin. Further analysis
for pairs from restricted azimuthal regions shows that the effective cluster
size at $\Delta\phi \sim 180^{\circ}$ drops more rapidly toward central
collisions than the size at $\Delta\phi \sim 0^{\circ}$. The effect of limited
$\eta$ acceptance on the cluster parameters is also addressed, and a correction
is applied to present cluster parameters for full $\eta$ coverage, leading to
much larger effective cluster sizes and widths than previously noted in the
literature. These results should provide insight into the hot and dense medium
created in heavy ion collisions.


title: Representations of the Renner Monoid

abstract:
  We describe irreducible representations and character formulas of the Renner
monoids for reductive monoids, which generalizes the Munn-Solomon
representation theory of rook monoids to any Renner monoids. The type map and
polytope associated with reductive monoids play a crucial role in our work. It
turns out that the irreducible representations of certain parabolic subgroups
of the Weyl groups determine the complete set of irreducible representations of
the Renner monoids. An analogue of the Munn-Solomon formula for calculating the
character of the Renner monoids, in terms of the characters of the parabolic
subgroups, is shown.


title: Cosmic-ray electron signatures of dark matter

abstract:
  There is evidence for an excess in cosmic-ray electrons at about 500 GeV
energy, that may be related to dark-matter annihilation. I have calculated the
expected electron contributions from a pulsar and from Kaluza-Klein dark
matter, based on a realistic treatment of the electron propagation in the
Galaxy. Both pulsars and dark-matter clumps are quasi-pointlike and few, and
therefore their electron contributions at Earth generally have spectra that
deviate from the average spectrum one would calculate for a smooth source
distribution. I find that pulsars younger than about 10^5 years naturally cause
a narrow peak at a few hundred GeV in the locally observed electron spectrum,
similar to that observed. On the other hand, for a density n_c = 10 /kpc^3 of
dark-matter clumps the sharp cut-off in the contribution from Kaluza-Klein
particles is sometimes more pronounced, but often smoothed out and
indistinguishable from a pulsar source, and therefore the spectral shape of the
electron excess is insufficient to discriminate a dark-matter origin from more
conventional astrophysical explanations. The amplitude of variations in the
spectral feature caused by dark matter predominantly depends on the density of
dark-matter clumps, which is not well known.


title: Higgs boson at LHC: a diffractive opportunity

abstract:
  An alternative process is presented for diffractive Higgs boson production in
peripheral $pp$ collisions, where the particles interact through the Double
Pomeron Exchange. The event rate is computed as a central-rapidity distribution
for Tevatron and LHC energies leading to a result around 0.6 pb, higher than
the predictions from previous approaches. Therefore, this result arises as an
enhanced signal for the detection of the Higgs boson in hadron colliders. The
predictions for the Higgs boson photoproduction are compared to the ones
obtained from a similar approach proposed by the Durham group, enabling an
analysis of the future developments of its application to $pp$ and $AA$
collisions.


title: Non-flow correlations in a cluster model

abstract:
  We derive analytical forms for nonflow contributions from cluster correlation
to the measurement of two-particle elliptic flow (v2{2}). We estimate nonflow
contribution from rho->pi+pi decays and find it is negative but not a major
contributor to the nonflow effect in v2{2}. We also estimate nonflow
contribution from the recent STAR measurement of two-particle angular
correlations.


title: Cutoff effects of Wilson fermions on the QCD equation of state to O(g^2)

abstract:
  We compute the O(g^2) contribution to the thermodynamic pressure for Wilson
fermions in the standard, the twisted mass, and clover improved formulation in
lattice perturbation theory, including finite mass effects. We compare the
continuum approaches of these discretizations for the massive ideal and
interacting gas. In all cases, for N_t \geq 8 cutoff effects of Wilson type
fermions are comparable to those of staggered fermions, but asymptotic scaling
requires $N_\tau>10$.


title:
A self-calibration approach for optical long baseline interferometry
  imaging

abstract:
  Current optical interferometers are affected by unknown turbulent phases on
each telescope. In the field of radio-interferometry, the self-calibration
technique is a powerful tool to process interferometric data with missing phase
information. This paper intends to revisit the application of self-calibration
to Optical Long Baseline Interferometry (OLBI). We cast rigorously the OLBI
data processing problem into the self-calibration framework and demonstrate the
efficiency of the method on real astronomical OLBI dataset.


title: Thermodynamics and Finite size scaling in Scalar Field Theory

abstract:
  In this work we consider the 1-component real scalar $\phi^4$ theory in 4
space-time dimensions on the lattice and investigate the finite size scaling of
thermodynamic quantities to study whether the thermodynamic limit is attained.
The results are obtained for the symmetric phase of the theory.


title:
Dynamical modelling of molecular constructions and setups for DNA
  unzipping

abstract:
  We present a dynamical model of DNA mechanical unzipping under the action of
a force. The model includes the motion of the fork in the sequence-dependent
landscape, the trap(s) acting on the bead(s), and the polymeric components of
the molecular construction (unzipped single strands of DNA, and linkers).
Different setups are considered to test the model, and the outcome of the
simulations is compared to simpler dynamical models existing in the literature
where polymers are assumed to be at equilibrium.


title: Diffractive Higgs boson photoproduction in peripheral collisions

abstract:
  An alternative process is proposed for the diffractive Higgs boson production
in peripheral $pp$ collisions, exploring it through the photon-proton
interaction by Double Pomeron Exchange. It is estimated the event rate of the
diffractive Higgs production in central rapidity for Tevatron and LHC energies,
being of the order of 1 fb, in agreement to the predictions from other
diffractive processes. The results are confronted with those obtained from a
similar approach of the Durham group.


title: A Magnetic Model for the Ordered Double Perovskites

abstract:
  We construct an effective spin model from the coupled spin-fermion problem
appropriate to double perovskites of the form A_2BB'O_6. The magnetic model
that emerges is reminiscent of double exchange and we illustrate this
`reduction' in detail for the case of perfect B-B' structural order, i.e, no
antisite disorder. We estimate the effective exchange between the magnetic B
ions in terms of the electronic parameters, study the `classical' magnetic
model using Monte Carlo techniques, and compare this approach to a full
numerical solution of the spin-fermion problem. The agreement is reasonable,
and promises a quick estimate of magnetic properties when coupled with ab
initio electronic structure. The scheme generalises to the presence of antisite
disorder.


title:
Modeling The Star Forming Universe at z=2: Impact of Cold Accretion
  Flows

abstract:
  We present results of a semi-analytic model (SAM) that includes cold
accretion and a porosity-based prescription for star formation. We can recover
the puzzling observational results of low $V/\sigma$ seen in various massive
disk or disk-like galaxies, if we allow 18 % of the accretion energy from cold
flows to drive turbulence in gaseous disks at $z=2$. The increase of gas mass
through cold flows is by itself not sufficient to increase the star formation
rate sufficiently to recover the number density of $\dot{M}_*>120$ M$_{\odot}$
yr$^{-1}$ galaxies in our model. In addition, it is necessary to increase the
star formation efficiency. This can be achieved naturally in the porosity
model, where star formation efficiency scales $\propto \sigma$, which scales as
cloud velocity dispersion. As cold accretion is the main driver for gas
velocity dispersion in our model, star formation efficiency parallels cold
accretion rates, and allows fast conversion into stars. At $z\sim 2$, we find a
space density $~10^{-4}$ Mpc$^{-3}$ in star-forming galaxies with
$\dot{M}_*>120$ M$_{\odot}$ yr$^{-1}$, in better agreement than earlier
estimates form SAMs. However, the fundamental relation between $\dot{M}_*$ and
$M_*$ is still offset from the observed relation, indicating the need for
possibly more efficient star formation at high z perhaps associated with a role
for AGN triggering.


title:
Invariant Manifolds for Viscous Profiles of a Class of Mixed
  Hyperbolic-Parabolic Systems

abstract:
  We are concerned with viscous profiles (travelling waves and steady
solutions) for mixed hyperbolic-parabolic systems in one space variable. For a
class of systems including the compressible Navier Stokes equation, these
profiles satisfy a singular ordinary differential equation in the form
\label{e:ab} dU / dt = F(U)/ z (U) . Here U takes values in $R^d$ and $F: R^d
\to R^d$ is a regular function. The real valued function $z (U)$ is as well
regular, but the equation is singular because $z (U)$ can attain the value 0.
We focus on a small enough neighbourhood of a point $\bar U$ satisfying $F(\bar
U) = \vec 0$, $z (\bar U) =0$. From the point of view of the applications to
the study of hyperbolic-parabolic systems this means restricting to systems
with small total variation. We discuss how to extend the notions of center
manifold and of uniformly stable manifold. Also, we give conditions ensuring
that if $z (U) \neq 0$ at $t=0$ then $z (U) \neq 0$ at every $t$. We provide an
example showing that if $z(U)$ becomes zero in finite time then in general the
solution $U$ of equation \eqref{e:ab} is not continuously differentiable.


title: Calculus with a Quaternionic Variable

abstract:
  Most of theoretical physics is based on the mathematics of functions of a
real or a complex variable; yet we frequently are drawn to try extending our
reach to include quaternions. The non-commutativity of the quaternion algebra
poses obstacles for the usual manipulations of calculus; but we show in this
paper how many of those obstacles can be overcome. The surprising result is
that the first order term in the expansion of F(x+delta) is a compact formula
involving both F'(x) and [F(x) - F(x*)]/(x-x*). This advance in the
differential calculus for quaternionic variables also leads us to some progress
in studying integration.


title:
Thermal hadron production in relativistic nuclear collisions: the hadron
  mass spectrum, the horn, and the QCD phase transition

abstract:
  We present, using the statistical model, a new analysis of hadron production
in central collisions of heavy nuclei. This study is motivated by the
availability of final measurements both for the SPS (beam energies 20-160 AGeV)
and for the RHIC energies ($\sqrt{s_{NN}}$=130 and 200 GeV) and by updates in
the hadron mass spectrum, which is a crucial input for statistical models.
Extending previous studies by inclusion of very high-mass resonances (m> 2
GeV), and the up-to-now neglected scalar $\sigma$ meson leads to an improved
description of the data. In particular, the hitherto poorly reproduced energy
dependence of the $K^+/\pi^+$ ratio at SPS energies ("the horn") is now well
described through the connection to the hadronic mass spectrum and, implicitly,
Hagedorn's limiting temperature. We thereby demonstrate the intimate connection
between the horn and the QCD phase transition.


title: The role of static disorder in negative thermal expansion in ReO3

abstract:
  Time-of-flight neutron powder diffraction and specific heat measurements were
used to study the nature of thermal expansion in rhenium trioxide, an
electrically conducting oxide with cubic symmetry. The temperature evolution of
the lattice parameters show that ReO3 can exhibit negative thermal expansion at
low temperatures and that the transition from negative to positive thermal
expansion depends on sample preparation; the single crystal sample demonstrated
the highest transition temperature, 300 K, and largest negative value for the
coefficient of thermal expansion, alpha = -1.1(1)x 10^-6 K^-1. For the oxygen
atoms, the atomic displacement parameters are strongly anisotropic even at 15
K, indicative of a large contribution of static disorder to the displacement
parameters. Further inspection of the temperature evolution of the oxygen
displacement parameters for different samples reveals that the static disorder
contribution is greater for the samples with diminished NTE behavior. In
addition, specific heat measurements show that ReO3 lacks the low energy
Einstein-type modes seen in other negative thermal expansion oxides such as
ZrW2O8.


title:
Low temperature specific heat of the hole-doped Ba_{0.6}K_{0.4}Fe_2As_2
  single crystals and electron-doped SmFeAsO_{0.9}F_{0.1} samples

abstract:
  Low temperature specific heat (SH) was measured on the FeAs-based
superconducting single crystals Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ and high
pressure synthesized polycrystalline samples SmFeAsO$_{0.9}$F$_{0.1}$. It is
found that the sharp SH anomaly $\Delta C/T|_{T_c}$ in
Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ reaches an unexpected high value of 98 mJ/mol
K$^2$, about one order of magnitude larger than that of
SmFeAsO$_{0.9}$F$_{0.1}$ ($6\sim8$ mJ/mol K$^2$) samples, suggesting very high
normal state quasiparticle density of states in FeAs-122 than in FeAs-1111.
Furthermore, we found that the electronic SH coefficient $\gamma_e(T)$ of
Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ is weakly temperature dependent and increases
almost linearly with the magnetic field in low temperature region, which may
indicate that the hole-doped FeAs-122 system contains a dominant component with
a full superconducting gap, although we cannot rule out the possibility of a
small component with anisotropic or nodal gap. A detailed analysis reveals that
the $\gamma_e(T)$ of Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ cannot be fitted with a
single gap of s-wave symmetry probably due to the multigap effect. These
results indicate clear difference between the properties of the superconducting
state of the holed-doped Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ and the F-doped
LnFeAsO (Ln = rare earth elements) systems, which we believe is originated from
the complex Fermi surface structures in different systems.


title:
Numerical Simulation of the Viscous-like Flow in and Around the Plasma
  Tail of a Comet

abstract:
  We model the interaction of the solar wind with the plasma tail of a comet by
means of numerical simulations, taking into account the effects of viscous-like
forces.A 2D hydrodynamical, two species, finite difference code has been
developed for the solution of the time dependent continuity, momentum and
energy conservation equations, as applied to the problem at hand. Velocity,
density and temperature profiles across the tail are obtained. Several cases
with different flow parameters are considered in order to study the relative
importance of viscous-like effects and the coupling between species on the flow
dynamics. Assuming a Mach number equal to 2 for the incident solar wind as it
flows past the comet nucleus, the flow exhibits three transitions with location
and properties depending on the Reynolds number for each species and on the
ratio of the timescale for inter-species coupling to the crossing time of the
free flowing solar wind. By comparing our results with the measurements taken
in situ by the Giotto spacecraft during its flyby of comet Halley we constrain
the flow parameters for both plasmas. In the context of our approximations, we
find that our model is qualitatively consistent with the in situ measurements
as long as the Reynolds number of the solar wind protons and of cometary H2O+
ions is low, less than 100, suggesting that viscous-like momentum transport
processes may play an important role in the interaction of the solar wind and
the plasma environment of comets.


title: Personnal recollections about the birth of string theory

abstract: Invited contribution to the collective book "The Birth of String Theory"


title: Three-body loss in lithium from functional renormalization

abstract:
  We use functional integral methods for an estimate of the three-body loss in
a three-component $^6$Li ultracold atom gas. We advocate a simple picture where
the loss proceeds by the formation of a three-atom bound state, the trion. In
turn, the effective amplitude for the trion formation from three atoms is
estimated from a simple effective boson exchange process. The energy gap of the
trion and other key quantities for the loss coefficient are computed in a
functional renormalization group framework.


title:
High-T_c superconductivity induced by doping rare earth elements into
  CaFeAsF

abstract:
  We have successfully synthesized the fluoride-arsenide compounds
Ca$_{1-x}$RE$_x$FeAsF (RE=Nd, Pr; x=0, 0.6). The x-ray powder diffraction
confirmed that the main phases of our samples are Ca$_{1-x}$RE$_x$FeAsF with
the ZrCuSiAs structure. By measuring resistivity, superconductivity was
observed at 57.4 K in Nd-doped and 52.8 K in Pr-doped samples with x=0.6. Bulk
superconductivity was also proved by the DC magnetization measurements in both
samples. Hall effect measurements revealed hole-like charge carriers in the
parent compound CaFeAsF with a clear resistivity anomaly below 118 K, while the
Hall coefficient $R_H$ in the normal state is negative for the superconducting
samples Ca$_{0.4}$Nd$_{0.6}$FeAsF and Ca$_{0.4}$Pr$_{0.6}$FeAsF. This indicates
that the rare earth element doping introduces electrons into CaFeAsF which
induces the high temperature superconductivity.


title: Some Applications of the Fractional Poisson Probability Distribution

abstract:
  Physical and mathematical applications of fractional Poisson probability
distribution have been presented. As a physical application, a new family of
quantum coherent states has been introduced and studied. As mathematical
applications, we have discovered and developed the fractional generalization of
Bell polynomials, Bell numbers, and Stirling numbers. Appearance of fractional
Bell polynomials is natural if one evaluates the diagonal matrix element of the
evolution operator in the basis of newly introduced quantum coherent states.
Fractional Stirling numbers of the second kind have been applied to evaluate
skewness and kurtosis of the fractional Poisson probability distribution
function. A new representation of Bernoulli numbers in terms of fractional
Stirling numbers of the second kind has been obtained. A representation of
Schlafli polynomials in terms of fractional Stirling numbers of the second kind
has been found. A new representations of Mittag-Leffler function involving
fractional Bell polynomials and fractional Stirling numbers of the second kind
have been discovered. Fractional Stirling numbers of the first kind have been
introduced and studied. Two new polynomial sequences associated with fractional
Poisson probability distribution have been launched and explored. The
relationship between new polynomials and the orthogonal Charlier polynomials
has also been investigated. In the limit case when the fractional Poisson
probability distribution becomes the Poisson probability distribution, all of
the above listed developments and implementations turn into the well-known
results of quantum optics, the theory of combinatorial numbers and the theory
of orthogonal polynomials of discrete variable.


title: Adversarial Scheduling in Evolutionary Game Dynamics

abstract:
  Consider a system in which players at nodes of an underlying graph G
repeatedly play Prisoner's Dilemma against their neighbors. The players adapt
their strategies based on the past behavior of their opponents by applying the
so-called win-stay lose-shift strategy. This dynamics has been studied in
(Kittock 94), (Dyer et al. 2002), (Mossel and Roch, 2006).
  With random scheduling, starting from any initial configuration with high
probability the system reaches the unique fixed point in which all players
cooperate. This paper investigates the validity of this result under various
classes of adversarial schedulers. Our results can be sumarized as follows:
  1. An adversarial scheduler that can select both participants to the game can
preclude the system from reaching the unique fixed point on most graph
topologies. 2. A nonadaptive scheduler that is only allowed to choose one of
the participants is no more powerful than a random scheduler. With this
restriction even an adaptive scheduler is not significantly more powerful than
the random scheduler, provided it is "reasonably fair".
  The results exemplify the adversarial scheduling approach we propose as a
foundational basis for the generative approach to social science (Epstein
2007).


title:
Universality and asymptotics of graph counting problems in nonorientable
  surfaces

abstract:
  Bender-Canfield showed that a plethora of graph counting problems in
oriented/unoriented surfaces involve two constants $t_g$ and $p_g$ for the
oriented and the unoriented case respectively. T.T.Q. Le and the authors
recently discovered a hidden relation between the sequence $t_g$ and a formal
power series solution $u(z)$ of the Painlev\'e I equation which, among other
things, allows to give exact asymptotic expansion of $t_g$ to all orders in
$1/g$ for large $g$. The paper introduces a formal power series solution $v(z)$
of a Riccati equation, gives a nonlinear recursion for its coefficients and an
exact asymptotic expansion to all orders in $g$ for large $g$, using the theory
of Borel transforms. In addition, we conjecture a precise relation between the
sequence $p_g$ and $v(z)$. Our conjecture is motivated by the enumerative
aspects of a quartic matrix model for real symmetric matrices, and the analytic
properties of its double scaling limit. In particular, the matrix model
provides a computation of the number of rooted quadrangulations in the
2-dimensional projective plane. Our conjecture implies analyticity of the
$\mathrm{O}(N)$ and $\mathrm{Sp}(N)$-types of free energy of an arbitrary
closed 3-manifold in a neighborhood of zero. Finally, we give a matrix model
calculation of the Stokes constants, pose several problems that can be answered
by the Riemann-Hilbert approach, and provide ample numerical evidence for our
results.


title:
Doubly periodic waves of a discrete nonlinear Schr\"odinger system with
  saturable nonlinearity

abstract:
  A system of two discrete nonlinear Schr\"odinger equations of the
Ablowitz-Ladik type with a saturable nonlinearity is shown to admit a doubly
periodic wave, whose long wave limit is also derived. As a by-product, several
new solutions of the elliptic type are provided for NLS-type discrete and
continuous systems.


title: A new determinantal formula for the classical discriminant

abstract:
  According to several classical results by Bezout, Sylvester, Cayley, and
others, the classical discriminant D_n of degree n polynomials may be expressed
as the determinant of a matrix whose entries are much simpler polynomials in
the coefficients of f. However, all of the determinantal formulae for D_n
appearing in the classical literature are equivalent in the sense that the
cokernels of their associated matrices are isomorphic as modules over the
associated polynomial ring. This begs the question of whether there exist
formulae which are not equivalent to the classical formulae and not trivial in
the sense of having the same cokernel as the 1 x 1 matrix (D_n).
  In this paper, we construct an explicit non-classical formula: the
presentation matrix of the open swallowtail first studied by Arnol'd and
Givental. We study the properties of this formula, contrasting them with the
properties of the classical formulae.


title: A chilean seismic regionalization through a Kohonen neural network

abstract:
  A study of seismic regionalization for central Chile based on a neural
network is presented. A scenario with six seismic regions is obtained,
independently of the size of the neighborhood or the reach of the correlation
between the cells of the grid. The high correlation between the spatial
distribution of the seismic zones and geographical data confirm our election of
the training vectors of the neural network.


title: Vector meson-vector meson interaction in a hidden gauge unitary approach

abstract:
  The formalism developed recently to study vector meson--vector meson
interaction, and applied to the case of $\rho\rho$, is extended to study the
interaction of the nonet of vector mesons among themselves. The interaction
leads to poles of the scattering matrix corresponding to bound states or
resonances. We show that 11 states (either bound or resonant) get dynamically
generated in nine strangeness-isospin-spin channels. Five of them can be
identified with those reported in the PDG, i.e., the $f_0(1370)$, $f_0(1710)$,
$f_2(1270)$, $f'_2(1525)$, and $K^*_2(1430)$. The masses of the latter three
tensor states have been used to fine-tune the free parameters of the unitary
approach, i.e., the subtraction constants in evaluating the vector meson
-vector meson loop functions in the dimensional regularization scheme. The
branching ratios of these five dynamically generated states are found to be
consistent with data. The existence of the other six states should be taken as
predictions to be tested by future experiments.