title:
Production of single top-quark final states at the LHC from
  supersymmetric FCNC interactions

abstract:
  We discuss the production of single top-quark final states by direct
supersymmetric flavor-changing interactions at the LHC. The total cross section
pp(gg)->t\bar{c}+\bar{t}c is computed at the 1-loop order within the
unconstrained MSSM. We prove that SUSY-QCD effects may furnish sizeable
production rates amounting up to barely 10^5 t\bar{c}(c\bar{t}) events per 100
fb^{-1} of integrated luminosity, in full compliance with the stringent
low-energy constraints from b->s gamma. Furthermore, we show that the
cooperative SUSY-EW effects can be sizeable on their own, regardless of the
SUSY-QCD contribution, with maximum production rates of the order of 10^3
events per 100 fb^{-1}. Owing to the fact that FCNC production of electrically
neutral heavy-quark pairs is virtually absent within the SM, we conclude that
the observation of such pp(gg)->t\bar{c}+\bar{t}c processes at the LHC could
lead to evidence of new physics - of likely supersymmetric nature.


title: Some Characterizations of VNL Rings

abstract:
  A ring R is said to be VNL if for any a in R, either a or 1-a is (von
Neumann) regular. The class of VNL rings lies properly between the exchange
rings and (von Neumann) regular rings. We characterize abelian VNL rings. We
also characterize and classify arbitrary VNL rings without infinite set of
orthogonal idempotents; and also the VNL rings having primitive idempotent e
such that eRe is not a division ring. We prove that a semiperfect ring R is VNL
if and only if for any right uni-modular row (a, b) in R^2, one of the a or b
is regular in R. Formal triangular matrix rings that are VNL, are also
characterized. As a corollary it is shown that an upper triangular matrix ring
T_n(R) is VNL if and only if n=2 or 3 and R is a division ring.


title: Outflows from Magnetorotational Supernovae

abstract:
  We discuss results of 2D simulations of magnetorotational(MR) mechanism of
core collapse supernova explosions. Due to the nonuniform collapse the
collapsed core rotates differentially. In the presence of initial poloidal
magnetic field its toroidal component appears and grows with time. Increased
magnetic pressure leads to foramtion of compression wave which moves outwards.
It transforms into the fast MHD shock wave (supernova shock wave). The shape of
the MR supernova explosion qualitatively depends on the configuration of the
initial magnetic field. For the dipole-like initial magnetic field the
supernova explosion develops mainly along rotational axis forming mildly
collimated jet. Quadrupole-like initial magnetic field leads to the explosion
developing mainly along equatorial plane. Magnetorotational instability was
found in our simulations. The supernova explosion energy is growing with
increase of the initial core mass and rotational energy of the core, and
corresponds to the observational data.


title: Study of scalar mesons in chiral Lagrangian frameworks

abstract:
  We review two approaches to studying pseudoscalar meson-meson scattering
amplitudes to beyond 1 GeV using non-linear and linear chiral Lagrangians.
These approaches use two different unitarisation techniques - a generalised
Breit Wigner prescription and K-matrix unitarization respectively. We also
report some preliminary findings on K-matrix unitarisation of the I=J=0
pion-pion scattering amplitude in the non-linear chiral Lagrangian approach and
make some remarks about the light scalar mesons.


title: The fidelity approach to the Hubbard model

abstract:
  We use the fidelity approach to quantum critical points to study the zero
temperature phase diagram of the one-dimensional Hubbard model. Using a variety
of analytical and numerical techniques, we analyze the fidelity metric in
various regions of the phase diagram, with particular care to the critical
points. Specifically we show that close to the Mott transition, taking place at
on-site repulsion U=0 and electron density n=1, the fidelity metric satisfies
an hyper-scaling form which we calculate. This implies that in general, as one
approaches the critical point U=0, n=1, the fidelity metric tends to a limit
which depends on the path of approach. At half filling, the fidelity metric is
expected to diverge as U^{-4} when U is sent to zero.


title: Curvature in conformal mappings of 2D lattices and foam structure

abstract:
  The elegant properties of conformal mappings, when applied to two dimensional
(2D) lattices, find interesting applications in 2D foams and other cellular or
close packed structures. In particular the 2D honeycomb (whose dual is the
triangular lattice) may be transformed into various conformal patterns, which
compare approximately to experimentally realisable 2D foams. We review and
extend the mathematical analysis of such transformations, with several
illustrative examples, and an account is given of the related work in energy
minimisation problems. New results are adduced for the local curvature
generated by the transformation.


title: Search for lepton-flavor-violating $\tau\to\ell V^0$ decays at Belle

abstract:
  We have searched for neutrinoless $\tau$ lepton decays into $\ell$ and $V^0$,
where $\ell$ stands for an electron or muon, and $V^0$ for a vector meson
($\phi$, $\omega$, $K^{*0}$, $\bar{K}^{*0}$ or $\rho^0$), using 543 fb$^{-1}$
of data collected with the Belle detector at the KEKB asymmetric-energy
$e^+e^-$ collider. No excess of signal events over the expected background has
been observed, and we set upper limits on the branching fractions in the range
$(5.9-18) \times 10^{-8}$ at the 90% confidence level. These upper limits
include the first results for the $\ell \omega$ mode as well as new limits that
are significantly more restrictive than our previous results for the $\ell
\phi$, $\ell K^{*0}$, $\ell \bar{K}^{*0}$ and $\ell \rho^0$ modes.


title: Simulating the Mass-Metallicity Relation from z=1

abstract:
  We use 112 N-body/hydrodynamical simulations in the standard Cold Dark Matter
universe, to follow the formation of galaxy-sized halos and investigate the
chemical enrichment of both the stellar component and the interstellar medium
of galaxies, with stellar masses larger than 1e9 Msun. The resulting chemical
properties of the simulated galaxies are broadly consistent with the
observations. The predicted relationship between the mean metallicity and the
galaxy stellar mass for both the stellar and the gaseous components at z=0 are
in agreement with the relationships observed locally. The predicted scatter
about these relationships, which is traced to the differing merging histories
amongst the simulated galaxies with similar final masses, is similar to that
observed. The predicted correlations between the total mass and the stellar
mass of galaxies in our simulated sample from the present epoch up to z=1 agree
with observed ones. The stellar mass versus metallicity relation and its
associated scatter are reproduced by the simulations as consequences of the
increasing efficiency of the conversion of gas into stars with stellar mass,
and the differing merging histories amongst the galaxies with similar masses.
The old ages of simulated low mass galaxies at z=0, and the weak level of
chemical evolution for massive galaxies suggest however that our modeling of
the supernova feedback may be incomplete, or that other feedback processes have
been neglected. (Abridged)


title: Stability and instability of weighted composition operators

abstract:
  Let $\epsilon >0$. A continuous linear operator
  $T:C(X) \ra C(Y)$ is said to be {\em $\epsilon$-disjointness preserving} if
$\vc (Tf)(Tg)\vd_{\infty} \le \epsilon$, whenever $f,g\in C(X)$ satisfy $\vc
f\vd_{\infty} =\vc g\vd_{\infty} =1$ and $fg\equiv 0$. In this paper we address
basically two main questions:
  1.- How close there must be a weighted composition operator to a given
$\epsilon$-disjointness preserving operator?
  2.- How far can the set of weighted composition operators be from a given
$\epsilon$-disjointness preserving operator?
  We address these two questions distinguishing among three cases: $X$
infinite, $X$ finite, and $Y$ a singleton ($\epsilon$-disjointness preserving
functionals).
  We provide sharp stability and instability bounds for the three cases.


title: Stochastic Porous Media Equation and Self-Organized Criticality

abstract:
  The existence and uniqueness of nonnegative strong solutions for stochastic
porous media equations with noncoercive monotone diffusivity function and
Wiener forcing term is proven. The finite time extinction of solutions with
high probability is also proven in 1-D. The results are relevant for
self-organized critical behaviour of stochastic nonlinear diffusion equations
with critical states.


title: In-situ frequency tuning of photons stored in a high Q microwave cavity

abstract:
  Photons are fundamental excitations of the electromagnetic field and can be
captured in cavities. For a given cavity with a certain size, the fundamental
mode has a fixed frequency f which gives the photons a specific "colour". The
cavity also has a typical lifetime tau, which results in a finite linewidth
delta f}. If the size of the cavity is changed fast compared to tau, and so
that the frequency change Delta f >> delta f, then it is possible to change the
"colour" of the captured photons. Here we demonstrate superconducting microwave
cavities, with tunable effective lengths. The tuning is obtained by varying a
Josephson inductance at one end of the cavity. We show tuning by several
hundred linewidths in a time Delta t << tau. Working in the few photon limit,
we show that photons stored in the cavity at one frequency will leak out from
the cavity with the new frequency after the detuning. The characteristics of
the measured devices make them suitable for dynamic coupling of qubits.


title:
Asynchronous Iterative Waterfilling for Gaussian Frequency-Selective
  Interference Channels

abstract:
  This paper considers the maximization of information rates for the Gaussian
frequency-selective interference channel, subject to power and spectral mask
constraints on each link. To derive decentralized solutions that do not require
any cooperation among the users, the optimization problem is formulated as a
static noncooperative game of complete information. To achieve the so-called
Nash equilibria of the game, we propose a new distributed algorithm called
asynchronous iterative waterfilling algorithm. In this algorithm, the users
update their power spectral density in a completely distributed and
asynchronous way: some users may update their power allocation more frequently
than others and they may even use outdated measurements of the received
interference. The proposed algorithm represents a unified framework that
encompasses and generalizes all known iterative waterfilling algorithms, e.g.,
sequential and simultaneous versions. The main result of the paper consists of
a unified set of conditions that guarantee the global converge of the proposed
algorithm to the (unique) Nash equilibrium of the game.


title: Lie algebras with S3 or S4-action, and generalized Malcev algebras

abstract:
  Lie algebras endowed with an action by automorphisms of any of the symmetric
groups S3 or S4 are considered, and their decomposition into a direct sum of
irreducible modules for the given action is studied.
  In case of S3-symmetry, the Lie algebras are coordinatized by some
nonassociative systems, which are termed generalized Malcev algebras, as they
extend the classical Malcev algebras. These systems are endowed with a binary
and a ternary products, and include both the Malcev algebras and the Jordan
triple systems.


title: On the Radiative Pion Decay

abstract:
  A reanalysis of the radiative pion decay together with the calculation of the
radiative corrections within chiral perturbation theory (CHPT) is performed.
The amplitude of this decay contains an inner Bremsstrahlung contribution and a
structure-dependent part that are both accessible in experiments. In order to
obtain a reliable estimate of the hadronic contributions we combine the CHPT
result with a large-N_C expansion and experimental data on other decays, which
makes it possible to determine the occurring coupling constants.


title: Missing experiments in quantum mechanics

abstract:
  We discuss the two-slit experiment and the Aharonov-Bohm (AB) experiment in
the magnetic field. In such a case the electron moving in the magnetic field
produces so called synchrotron radiation. In other words the photons are
emitted from the points of the electron trajectory and it means that the
trajectory of electron is visible in the synchrotron radiation spectrum. The
axiomatic system of quantum mechanics does not enable to define the trajectory
of the elementary particle. The two-slit experiment and AB experiment in a
magnetic field was never performed and it means that they are the missing
experiments of quantum mechanics. The extension of the discussion to the
cosmical rays moving in the magnetic field of the Saturn magnetosphere and its
rings is mentioned. It is related to the probe CASSINI. The solution of the
problem in the framework of the hydrodynamical model of quantum mechanics and
the nonlinear quantum mechanics is also mentioned.


title: Quantifying systematic uncertainties in supernova cosmology

abstract:
  Observations of Type Ia supernovae used to map the expansion history of the
Universe suffer from systematic uncertainties that need to be propagated into
the estimates of cosmological parameters. We propose an iterative Monte-Carlo
simulation and cosmology fitting technique (SMOCK) to investigate the impact of
sources of error upon fits of the dark energy equation of state. This approach
is especially useful to track the impact of non-Gaussian, correlated effects,
e.g. reddening correction errors, brightness evolution of the supernovae,
K-corrections, gravitational lensing, etc. While the tool is primarily aimed
for studies and optimization of future instruments, we use the ``Gold''
data-set in Riess et al. (2007) to show examples of potential systematic
uncertainties that could exceed the quoted statistical uncertainties.


title: Xenon in Mercury-Manganese Stars

abstract:
  Previous studies of elemental abundances in Mercury-Manganese (HgMn) stars
have occasionally reported the presence of lines of the ionized rare noble gas
Xe II, especially in a few of the hottest stars with Teff ~ 13000--15000 K. A
new study of this element has been undertaken using observations from Lick
Observatory's Hamilton Echelle Spectrograph. In this work, the spectrum
synthesis program UCLSYN has been used to undertake abundance analysis assuming
LTE. We find that in the Smith & Dworetsky sample of HgMn stars, Xe is vastly
over-abundant in 21 of 22 HgMn stars studied, by factors of 3.1--4.8 dex. There
does not appear to be a significant correlation of Xe abundance with Teff. A
comparison sample of normal late B stars shows no sign of Xe II lines that
could be detected, consistent with the expected weakness of lines at normal
abundance. The main reason for the previous lack of widespread detection in
HgMn stars is probably due to the strongest lines being at longer wavelengths
than the photographic blue. The lines used in this work were 4603.03A, 4844.33A
and 5292.22A.


title: Isometric embeddings of compact spaces into Banach spaces

abstract:
  We show the existence of a compact metric space $K$ such that whenever $K$
embeds isometrically into a Banach space $Y$, then any separable Banach space
is linearly isometric to a subspace of $Y$. We also address the following
related question: if a Banach space $Y$ contains an isometric copy of the unit
ball or of some special compact subset of a separable Banach space $X$, does it
necessarily contain a subspace isometric to $X$? We answer positively this
question when $X$ is a polyhedral finite-dimensional space, $c_0$ or $\ell_1$.


title: On the number of droplets in aerosols

abstract:
  The number of droplets which may be formed with a supersaturated vapor in
presence of a gas cannot exceed a number proportional to (pv-pvo)4 where pv and
pvo denote at the same temperature the pressure of the supersaturated vapor-gas
mixture and the pressure of the saturated vapor-gas mixture. The energy
necessary to the droplet formation is also bounded by a number proportional to
(pv-pvo)2 .


title: Generating entangled light with atomic ensembles

abstract: This paper has been withdrawn by the author due to some problems.


title:
Light-induced scattering and energy transfer between
  orthogonally-polarized waves

abstract:
  We present a detailed experimental investigation on polarization-isotropic
and polarization-anisotropic holographic scattering in lithium niobate crystal
doped with iron when recording parasitic gratings with an ordinary polarized
pump beam. The kinetics of both types of scattering during the whole process of
recording is studied. Holographic scattering is presented as a simple technique
to monitor the energy transfer between beams of different polarization.
Moreover, the spectral and the angular dependence of the transmitted intensity
of the crystal during the reconstruction of the auto-generated parasitic
gratings are measured.


title:
The effect of oscillating Fermi energy on the line shape of the
  Shubnikov-de Haas oscillation in a two dimensional electron gas

abstract:
  The line shape of the Shubnikov-de Haas (SdH) oscillation has been analyzed
in detail for a GaAs/AlGaAs two-dimensional electron gas. The line shape, or
equivalently the behavior of the Fourier components, of the experimentally
observed SdH oscillation is well reproduced by the sinusoidal density of states
at the Fermi energy that oscillates with a magnetic field in a saw-tooth shape
to keep the electron density constant. This suggests that the broadening of
each Landau level by disorder is better described by a Gaussian than by a
Lorentzian.


title: Dynamics of Annihilation II: Fluctuations of Global Quantities

abstract:
  We develop a theory for fluctuations and correlations in a gas evolving under
ballistic annihilation dynamics. Starting from the hierarchy of equations
governing the evolution of microscopic densities in phase space, we
subsequently restrict to a regime of spatial homogeneity, and obtain explicit
predictions for the fluctuations and time correlation of the total number of
particles, total linear momentum and total kinetic energy. Cross-correlations
between these quantities are worked out as well. These predictions are
successfully tested against Molecular Dynamics and Monte-Carlo simulations.
This provides strong support for the theoretical approach developed, including
the hydrodynamic treatment of the spectrum of the linearized Boltzmann
operator. This article is a companion paper to arXiv:0801.2299 and makes use of
the spectral analysis reported there.


title:
Modulation of the Shubnikov-de Haas Oscillation in Unidirectional
  Lateral Superlattices

abstract:
  The amplitude and phase of Shubnikov-de Haas oscillations have been analyzed
in detail for two-dimensional electron gases subjected to a weak unidirectional
periodic potential modulation. The amplitude is suppressed, accompanied by
inversion of the phase, at the maximum bandwidth conditions at low magnetic
fields. The suppression is gradually taken over by the enhancement with the
increase of the magnetic fields. The suppression and the enhancement are
attributable to the collisional and the diffusion contribution of the modulated
potential to the conductivity, respectively, the former (the latter) being
dominant at low (high) magnetic fields. A theoretical calculation that takes
the two types of contributions into account shows semi-quantitative agreement
with experimental traces.


title: Scarring for Quantum Maps with Simple Spectrum

abstract:
  We previously introduced a family of symplectic maps of the torus whose
quantization exhibits scarring on invariant co-isotropic submanifolds. The
purpose of this note is to show that in contrast to other examples, where
failure of Quantum Unique Ergodicity is attributed to high multiplicities in
the spectrum, for these examples the spectrum is (generically) simple.


title: Motives of hypersurfaces of very small degree

abstract:
  We study the Chow motive (with rational coefficients) of a hypersurface X in
the projective space by using the variety F(X) of l-dimensional planes
contained in X. If the degree of X is sufficiently small we show that the
primitive part of the motive of X is the tensor product of a direct summand in
the motive of a suitable complete intersection in F(X) and the l-th twist Q(-l)
of the Lefschetz motive.


title:
Incommensurate magnetic ground state revealed by RXS in the frustrated
  spin system Ca3Co2O6

abstract:
  We have performed a resonant x-ray scattering study at the Co pre-K edge on a
single crystal of Ca3Co2O6. The measurements reveal an abrupt transition to a
magnetically ordered state immediately below T_N = 25 K, with a magnetic
correlation length in excess of 5500 {\AA} along the c-axis chains. There is no
evidence for modifications to the Co$^{3+}$ spin state. A temperature dependent
modulation in the magnetic order along the c-axis and an unusual decrease in
the magnetic correlation lengths on cooling are observed. The results are
compatible with the onset of a partially disordered antiferromagnetic structure
in Ca3Co2O6.


title:
A new approach to the representation theory of the symmetric groups. IV.
  $ \Bbb Z_{2}$-graded groups and algebras

abstract:
  We start with definitions of the general notions of the theory of $\Bbb
Z_{2}$-graded algebras. Then we consider theory of inductive families of $\Bbb
Z_{2}$-graded semisimple finite-dimensional algebras and its representations in
the spirit of approach of the papers \cite{VO,OV} to representation theory of
symmetric groups. The main example is the classical - theory of the projective
representations of symmetric groups.


title: Physical and orbital properties of the Trojan asteroids

abstract:
  All the Trojan asteroids orbit about the Sun at roughly the same heliocentric
distance as Jupiter. Differences in the observed visible reflection spectra
range from neutral to red, with no ultra-red objects found so far. Given that
the Trojan asteroids are collisionally evolved, a certain degree of variability
is expected. Additionally, cosmic radiation and sublimation are important
factors in modifying icy surfaces even at those large heliocentric distances.
We search for correlations between physical and dynamical properties, we
explore relationships between the following four quantities; the normalised
visible reflectivity indexes ($S'$), the absolute magnitudes, the observed
albedos and the orbital stability of the Trojans. We present here visible
spectroscopic spectra of 25 Trojans. This new data increase by a factor of
about 5 the size of the sample of visible spectra of Jupiter Trojans on
unstable orbits. The observations were carried out at the ESO-NTT telescope
(3.5m) at La Silla, Chile, the ING-WHT (4.2m) and NOT (2.5m) at Roque de los
Muchachos observatory, La Palma, Spain. We have found a correlation between the
size distribution and the orbital stability. The absolute-magnitude
distribution of the Trojans in stable orbits is found to be bimodal, while the
one of the unstable orbits is unimodal, with a slope similar to that of the
small stable Trojans. This supports the hypothesis that the unstable objects
are mainly byproducts of physical collisions. The values of $S'$ of both the
stable and the unstable Trojans are uniformly distributed over a wide range,
from $0 %/1000\AA $ to about $15 %/1000\AA$. The values for the stable Trojans
tend to be slightly redder than the unstable ones, but no significant
statistical difference is found.


title:
An Application of the Feferman-Vaught Theorem to Automata and Logics
  for<br> Words over an Infinite Alphabet

abstract:
  We show that a special case of the Feferman-Vaught composition theorem gives
rise to a natural notion of automata for finite words over an infinite
alphabet, with good closure and decidability properties, as well as several
logical characterizations. We also consider a slight extension of the
Feferman-Vaught formalism which allows to express more relations between
component values (such as equality), and prove related decidability results.
  From this result we get new classes of decidable logics for words over an
infinite alphabet.


title: Plane geometry and convexity of polynomial stability regions

abstract:
  The set of controllers stabilizing a linear system is generally non-convex in
the parameter space. In the case of two-parameter controller design (e.g. PI
control or static output feedback with one input and two outputs), we observe
however that quite often for benchmark problem instances, the set of
stabilizing controllers seems to be convex. In this note we use elementary
techniques from real algebraic geometry (resultants and Bezoutian matrices) to
explain this phenomenon. As a byproduct, we derive a convex linear matrix
inequality (LMI) formulation of two-parameter fixed-order controller design
problem, when possible.


title: Making, probing and understanding ultracold Fermi gases

abstract: A review on superfluidity and the BEC-BCS crossover in ultracold Fermi gases.


title: Mona Lisa, the stochastic view and fractality in color space

abstract:
  A painting consists of objects which are arranged in specific ways. The art
of painting is drawing the objects, which can be considered as known trends, in
an expressive manner. Detrended methods are suitable for characterizing the
artistic works of the painter by eliminating trends. It means that we study the
paintings, regardless of its apparent purpose, as a stochastic process. We
apply multifractal detrended fluctuation analysis to characterize the
statistical properties of Mona Lisa, as an instance, to exhibit the fractality
of the painting. Our results show that Mona Lisa is long range correlated and
almost behaves similar in various scales.


title:
Superconductor-Insulator Phase Separation Induced by Rapid Cooling in
  kappa-(ET)_2Cu[N(CN)_2]Br

abstract:
  We present measurements of the low temperature specific heat of single
crystals of kappa-(ET)_2Cu[N(CN)_2]Br as a function of the cooling rate through
the glasslike structure transition at $\sim$ 80K. We find that rapid cooling
produces a small (< 4%) decrease in the superconducting transition temperature
accompanied by a substantial (up to 50%) decrease in the normal-state
electronic specific heat. A natural explanation of our data is that there is a
macroscopic phase separation between superconducting and insulating regions in
rapidly cooled samples.


title:
Far Ultraviolet Spectral Analysis of the Prototype Nova-Like Variable VY
  Sculptoris from the High State to the Low State

abstract:
  The prototype nova-like variable VY Sculptoris was observed by the IUE during
four different optical brightness states of the system. The FUV flux level from
the highest state to the lowest state declines by a factor of 28. We have
carried out model accretion disk and white dwarf atmosphere fitting to the
spectra. The corresponding accretion rates range from $\dot{M}= 8 \times
10^{-9}$M$_{\sun}$ yr$^{-1}$ at the highest FUV flux level down to $\dot{M}=
1.9\times 10^{-10}$M$_{\sun}$ yr$^{-1}$ at the lowest flux level. We report
tentative evidence for the detection of the underlying white dwarf with $T_{\rm
eff} = 45,000$K in the spectrum with the lowest flux level.


title:
Simulated Dark-Matter Halos as a Test of Nonextensive Statistical
  Mechanics

abstract:
  In the framework of nonextensive statistical mechanics, the equilibrium
structures of astrophysical self-gravitating systems are stellar polytropes,
parameterized by the polytropic index n. By careful comparison to the
structures of simulated dark-matter halos we find that the density profiles, as
well as other fundamental properties, of stellar polytropes are inconsistent
with simulations for any value of n. This result suggests the need to
reconsider the applicability of nonextensive statistical mechanics (in its
simplest form) to equilibrium self-gravitating systems.


title: Uniformly spread measures and vector fields

abstract:
  We show that two different ideas of uniform spreading of locally finite
measures in the d-dimensional Euclidean space are equivalent. The first idea is
formulated in terms of finite distance transportations to the Lebesgue measure,
while the second idea is formulated in terms of vector fields connecting a
given measure with the Lebesgue measure.


title: Comment on "Quantum Key Distribution in the Holevo Limit"

abstract:
  In a Letter, Cabello proposed a quantum key distribution (QKD) Protocol which
attended to Holevo limit. In this comment, we show that Eve could use a simple
plan to distinguish among quantum keys, without being detected by Alice and
Bob. In following, we show that our approach is not restricted to Cabello
Protocol. With attention to our Eavesdropping approach, it seems that Mor's
arguments for no-cloning principal for orthogonal states is not general enough
to avoid eavesdropping.


title:
Characters of the Grothendieck-Teichmueller group through rigidity of
  the Burau representation

abstract:
  We present examples of characters of absolute Galois groups of number fields
that can be recovered through their action by automorphisms on the profinite
completion of the braid groups, using a ``rigidity'' approach. The way we use
to recover them is through classical representations of the braid groups, and
in particular through the Burau representation. This enables one to extend
these characters to Grothendieck-Teichmueller groups.


title:
Reply to Fahmi and Golshani's comment on "Quantum key distribution in
  the Holevo limit"

abstract:
  As Fahmi and Golshani correctly point out, a protocol introduced in A.
Cabello, Phys. Rev. Lett. 85, 5635 (2000), to show that a quantum key
distribution protocol can have efficiency one (i.e., can achieve the Holevo
limit), does indeed not have efficiency one. The corrected protocol, introduced
in A. Cabello, Recent. Res. Devel. Physics 2, 249 (2001), is reproduced here.


abstract:
  The aim of this paper is to prove an analogue of Baxter's inequality for
fractional Brownian motion-type processes with Hurst index less than 1/2. This
inequality is concerned with the norm estimate of the difference between
finite- and infinite-past predictor coefficients.


title:
A Comparison of natural (english) and artificial (esperanto) languages.
  A Multifractal method based analysis

abstract:
  We present a comparison of two english texts, written by Lewis Carroll, one
(Alice in wonderland) and the other (Through a looking glass), the former
translated into esperanto, in order to observe whether natural and artificial
languages significantly differ from each other. We construct one dimensional
time series like signals using either word lengths or word frequencies. We use
the multifractal ideas for sorting out correlations in the writings. In order
to check the robustness of the methods we also write the corresponding shuffled
texts. We compare characteristic functions and e.g. observe marked differences
in the (far from parabolic) f(alpha) curves, differences which we attribute to
Tsallis non extensive statistical features in the ''frequency time series'' and
''length time series''. The esperanto text has more extreme vallues. A very
rough approximation consists in modeling the texts as a random Cantor set if
resulting from a binomial cascade of long and short words (or words and
blanks). This leads to parameters characterizing the text style, and most
likely in fine the author writings.


title:
Thermodynamic Limit for the Invariant Measures in Supercritical Zero
  Range Processes

abstract:
  We prove a strong form of the equivalence of ensembles for the invariant
measures of zero range processes conditioned to a supercritical density of
particles. It is known that in this case there is a single site that
accomodates a macroscopically large number of the particles in the system. We
show that in the thermodynamic limit the rest of the sites have joint
distribution equal to the grand canonical measure at the critical density. This
improves the result of Gro\ss kinsky, Sch\"{u}tz and Spohn, where convergence
is obtained for the finite dimensional marginals. We obtain as corollaries
limit theorems for the order statistics of the components and for the
fluctuations of the bulk.


title:
Electron angular correlation in neutrinoless double beta decay and new
  physics

abstract:
  The angular correlation of the electrons in the neutrinoless double beta
decay ($0\nu2\beta$) is calculated taking into account the nucleon recoil, the
$S$ and $P$-waves for the electrons and the electron mass using a general
Lorentz invariant effective Lagrangian. We show that the angular coefficient is
essentially independent of the nuclear matrix element models. We work out the
angular coefficient in several scenarios for new physics, in particular, in the
left-right symmetric models.


title:
A Pair of Smarandachely Isotopic Quasigroups and Loops of the Same
  Variety

abstract:
  The isotopic invariance or universality of types and varieties of quasigroups
and loops described by one or more equivalent identities has been of interest
to researchers in loop theory in the recent past. A variety of
quasigroups(loops) that are not universal have been found to be isotopic
invariant relative to a special type of isotopism or the other. Presently,
there are two outstanding open problems on universality of loops: semi
automorphic inverse property loops(1999) and Osborn loops(2005). Smarandache
isotopism(S-isotopism) was originally introduced by Vasantha Kandasamy in 2002.
But in this work, the concept is re-restructured in order to make it more
explorable. As a result of this, the theory of Smarandache isotopy inherits the
open problems as highlighted above for isotopy. In this short note, the
question 'Under what type of S-isotopism will a pair of S-quasigroups(S-loops)
form any variety?' is answered by presenting a pair of specially S-isotopic
S-quasigroups(loops) that both belong to the same variety of
S-quasigroups(S-loops). This is important because pairs of specially S-isotopic
S-quasigroups(e.g Smarandache cross inverse property quasigroups) that are of
the same variety are useful for applications(e.g cryptography).


title: Trapping cold Atoms by Quantum Reflection

abstract:
  We examine the properties of a quantum reflection trap when
particle-interaction is included. We explore the influence of the
particle-interaction on the trapping for different regimes: repulsive
particle-interaction and attractive particle-interaction in its stable and
unstable limit. With variational techniques, we calculate the phase-diagram of
the quatum reflection trap and determine the stable and unstable regimes of the
system.


title: Ion beam shaping and downsizing of nanostructures

abstract:
  We report a new approach for progressive and well-controlled downsizing of
nanostructures below the 10 nm scale. Low energetic ion beam (Ar+) is used for
gentle surface erosion, progressively shrinking the dimensions with ~ 1 nm
accuracy. The method enables shaping of nanostructure geometry and polishing
the surface. The process is clean room / high vacuum compatible being suitable
for various applications. Apart from technological advantages, the method
enables study of various size phenomena on the same sample between sessions of
ion beam treatment.


title: Quantum fluctuations in ultranarrow superconducting nanowires

abstract:
  Progressive reduction of the effective diameter of a nanowire is applied to
trace evolution of the shape of superconducting transition $R(T)$ in
quasi-one-dimensional aluminum structures. In nanowires with effective diameter
$\leq$ 15 nm the $R(T)$ dependences are much wider than predicted by the model
of thermally activated phase slips. The effect can be explained by quantum
fluctuations of the order parameter. Negative magnetoresistance is observed in
the thinest samples. Experimental results are in reasonable agreement with
existing theoretical models. The effect should have a universal validity
indicating a breakdown of zero resistance state in a superconductor below a
certain scale.


title: Bilinear R-parity Violation in Rare Meson Decays

abstract:
  We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ +$ and $D^ +
\to K^ - \ell ^ + \ell '^ +$ ($\ell ,\ell ' = e,\mu $) in a supersymmetric
extension of the standard model with explicit breaking of R-parity by bilinear
Yukawa couplings in the superpotential. Estimates of the branching ratios for
these decays are given. We also compare our numerical results with analogous
ones previously obtained for two other mechanisms of lepton number violation:
exchange by massive Majorana neutrinos and trilinear R-parity violation.


title: GOSSIP, a new VO compliant tool for SED fitting

abstract:
  We present GOSSIP (Galaxy Observed-Simulated SED Interactive Program), a new
tool developed to perform SED fitting in a simple, user friendly and efficient
way. GOSSIP automatically builds-up the observed SED of an object (or a large
sample of objects) combining magnitudes in different bands and eventually a
spectrum; then it performs a chi-square minimization fitting procedure versus a
set of synthetic models. The fitting results are used to estimate a number of
physical parameters like the Star Formation History, absolute magnitudes,
stellar mass and their Probability Distribution Functions. User defined models
can be used, but GOSSIP is also able to load models produced by the most
commonly used synthesis population codes. GOSSIP can be used interactively with
other visualization tools using the PLASTIC protocol for communications.
Moreover, since it has been developed with large data sets applications in
mind, it will be extended to operate within the Virtual Observatory framework.
GOSSIP is distributed to the astronomical community from the PANDORA group web
site (http://cosmos.iasf-milano.inaf.it/pandora/gossip.html)


title: Luminous Blue Variables & Mass Loss near the Eddington Limit

abstract:
  During the course of their evolution, massive stars lose a substantial
fraction of their initial mass, both through steady winds and through
relatively brief eruptions during their Luminous Blue Variable (LBV) phase.
This talk reviews the dynamical driving of this mass loss, contrasting the
line-driving of steady winds to the potential role of continuum driving for
eruptions during LBV episodes when the star exceeds the Eddington limit. A key
theme is to emphasize the inherent limits that self-shadowing places on
line-driven mass loss rates, whereas continuum driving can in principle drive
mass up to the "photon-tiring" limit, for which the energy to lift the wind
becomes equal to the stellar luminosity. We review how the "porosity" of a
highly clumped atmosphere can regulate continuum-driven mass loss, but also
discuss recent time-dependent simulations of how base mass flux that exceeds
the tiring limit can lead to flow stagnation and a complex, time-dependent
combination of inflow and outflow regions. A general result is thus that
porosity-mediated continuum driving in super-Eddington phases can explain the
large, near tiring-limit mass loss inferred for LBV giant eruptions.


title: Synchronization of Non-Linear Random Walk Dynamics in Complex Network

abstract:
  This work addresses synchronization in transient, non-linear stochastic
dynamics corresponding to accesses performed by self-avoiding walks originating
at each node of a complex network. More specifically, the synchronizability of
accesses incoming from other nodes has been considered and quantified in terms
of the entropy of the mean periods of access, being closely associated to the
efficiency of access delivery to each node. The concept of synchronous support
of a node $i$ has also been suggested as corresponding to the nodes which
contribute the most for the synchronization of the accesses to $i$. These
concepts have been applied to the analysis of 6 networks of different types,
leading to markedly smaller synchronizability being obtained for the
Watts-Strogatz and a geographical models. The more uniform synchronizabilities
were identified for the Watts-Strogatz and path-regular structures. Varying
degrees of correlations were found between the synchronizability and the degree
or outward accessibility of the nodes. The synchronous support of a node $i$
has been found to present diverse structure, including nodes which may be near
to $i$, or nodes which are scattered through the network and far away from $i$.


title:
Frequency Dependence of the Critical Velocity of a Sphere Oscillating in
  Superfluid Helium-4

abstract:
  It is shown that the critical velocity of a small sphere oscillating in
superfluid helium increases with the square root of the oscillation frequency.
This behavior can be described by a simple dimensional argument. The size of
the sphere and the temperature of the superfluid are found to have no or only
very little effect. Surface properties of the sphere and remanent vorticity may
have an influence but have not been under systematic investigation in these
measurements


title: Fractional Loop Group and Twisted K-Theory

abstract:
  We study the structure of abelian extensions of the group $L_qG$ of
$q$-differentiable loops (in the Sobolev sense), generalizing from the case of
central extension of the smooth loop group. This is motivated by the aim of
understanding the problems with current algebras in higher dimensions. Highest
weight modules are constructed for the Lie algebra. The construction is
extended to the current algebra of supersymmetric Wess-Zumino-Witten model. An
application to the twisted K-theory on $G$ is discussed.


title: Proto-Neutron and Neutron Stars

abstract:
  The parity doublet model, containing the SU(2) multiplets including the
baryons identified as the chiral partners of the nucleons is applied to neutron
stars. The maximum mass for the star is calculated for different stages of the
cooling taking into account finite temperature/entropy effect, trapped
neutrinos and fixed baryon number. Rotation effects are also included.


title:
A variant of the tandem duplication - random loss model of genome
  rearrangement

abstract:
  In Soda'06, Chaudhuri, Chen, Mihaescu and Rao study algorithmic properties of
the tandem duplication - random loss model of genome rearrangement, well-known
in evolutionary biology. In their model, the cost of one step of
duplication-loss of width k is $\alpha^k$ for $\alpha =1$ or $\alpha >=2 $. In
this paper, we study a variant of this model, where the cost of one step of
width $k$ is 1 if $k <= K$ and $\infty$ if $k > K$, for any value of the
parameter $K in N$. We first show that permutations obtained after $p$ steps of
width $K$ define classes of pattern-avoiding permutations. We also compute the
numbers of duplication-loss steps of width $K$ necessary and sufficient to
obtain any permutation of $S_n$, in the worst case and on average. In this
second part, we may also consider the case $K=K(n)$, a function of the size $n$
of the permutation on which the duplication-loss operations are performed.


title: Combinatorial Characterization of the Assur Graphs from Engineering

abstract:
  We introduce the idea of Assur graphs, a concept originally developed and
exclusively employed in the literature of the kinematics community. The paper
translates the terminology, questions, methods and conjectures from the
kinematics terminology for one degree of freedom linkages to the terminology of
Assur graphs as graphs with special properties in rigidity theory. Exploiting
recent works in combinatorial rigidity theory we provide mathematical
characterizations of these graphs derived from minimal linkages. With these
characterizations, we confirm a series of conjectures posed by Offer Shai, and
offer techniques and algorithms to be exploited further in future work.


title: The variance of the shock in the HAD process

abstract:
  We consider the Hammersley-Aldous-Diaconis (HAD) process with sinks and
sources such that there is a microscopic shock at every time $t$; denote $Z(t)$
its position. We show that the mean and variance of $Z(t)$ are linear functions
of $t$ and compute explicitely the respective constants in function of the left
and right densities. Furthermore, we describe the dependence of $Z(t)$ on the
initial configuration in the scale $\sqrt t$ and, as a corollary, prove a
central limit theorem.


title: Familon Model of Dark Matter

abstract:
  If the next fundamental level of matter occurs (preons) then dark matter must
consist of familons containing a "hot" component from massless particles and a
"cold" component from massive particles. During evolution of the Universe this
dark matter was undergone to late-time relativistic phase transitions
temperatures of which were different. Fluctuations created by these phase
transitions have had a fractal character. In the result the structurization of
dark matter (and therefore the baryon subsystem) has taken place and in the
Universe some characteristic scales which have printed this phenomenon arise
naturally. Familons are collective excitations of nonperturbative preon
condensates which could be produced during more early relativistic phase
transition. For structurization of dark matter (and baryon component) three
generations of particles are necessary. The first generation of particles has
produced the observed baryon world. The second and third generations have
produced dark matter from particles which have appeared when symmetry among
generations was spontaneously broken.


title:
Direct evidence of the self-compression of injected electron-hole plasma
  in silicon

abstract:
  A surface distribution of the electroluminescence intensity of silicon p-n
light emitting diodes is obtained under space scanning experiments at room
temperature. An emitting surface of the diodes, represented by a few small
bright emitting dots and a weakly emitting area outside the dots, serves as a
direct evidence of the self-compression of injected electron-hole plasma in
silicon. The plasma self-compression explains concentration of injected
carriers into one or a few strongly emitting plasma drops.


title:
Chemical abundances in six nearby star-forming regions: implications for
  galactic evolution and planet searches around very young stars

abstract:
  In this paper we present a study of chemical abundances in six star-forming
regions. Stellar parameters and metallicities are derived using
high-resolution, high S/N spectra of weak-line T-Tauri stars in each region.
The results show that nearby star-forming regions have a very small abundance
dispersion (only 0.033dex in [Fe/H]). The average metallicity found is slightly
below that of the Sun, although compatible with solar once the errors are taken
into account. The derived abundances for Si and Ni show that the observed stars
have the abundances typical of Galactic thin disk stars of the same
metallicity. The impact of these observations is briefly discussed in the
context of the Galactic chemical evolution, local inter-stellar medium
abundances, and in the origin of metal-rich stars in the solar neighbourhood
(namely, stars more likely to harbour planets). The implication for future
planet-search programmes around very young, nearby stars is also discussed.


title:
Une nouvelle analyse des mesures maximisant l'entropie des
  diff\'eomorphismes d'Anosov de surfaces

abstract:
  This note illustrates the strategy of our paper on piecewise affine surface
homeomorphisms by giving a new proof of the finite multiplicity of the maximum
entropy measure of Anosov diffeomorphisms (here on surfaces). This approach
avoids the explicit construction of Markov partitions and will be applied
elsewhere to some non-uniformly hyperbolic diffeomorphisms.


title: Quantum channels that preserve entanglement

abstract:
  Let M and N be full matrix algebras. A unital completely positive (UCP) map
\phi:M\to N is said to preserve entanglement if its inflation \phi\otimes \id_N
: M\otimes N\to N\otimes N has the following property: for every maximally
entangled pure state \rho of N\otimes N, \rho\circ(\phi\otimes \id_N) is an
entangled state of M\otimes N.
  We show that there is a dichotomy in that every UCP map that is not
entanglement breaking in the sense of Horodecki-Shor-Ruskai must preserve
entanglement, and that entanglement preserving maps of every possible rank
exist in abundance. We also show that with probability 1, {\em all} UCP maps of
relatively small rank preserve entanglement, but that this is not so for UCP
maps of maximum rank.


title:
Simbol-X capability of detecting the non-thermal emission of stellar
  flares

abstract:
  We investigate the capability of detecting, with Simbol-X, non-thermal
emission during stellar flares, and distinguishing it from hot thermal
emission. We find that flare non-thermal emission is detectable when at least
~20 cts are detected with the CZT detector in the 20-80 keV band. Therefore
Simbol-X will detect the non-thermal emission from some of the X-ray brightest
nearby stars, whether the thermal vs. non-thermal relation, derived for solar
flares, holds.


title:
Correlation between spin helicity and electric polarization vector in
  quantum-spin chain magnet LiCu$_2$O$_2$

abstract:
  Measurements of polarized neutron scattering were performed on a $S=1/2$
chain multiferroic LiCu$_2$O$_2$. In the ferroelectric ground state with the
spontaneous polarization along the c-axis, the existence of transverse spiral
spin component in the $bc$-plane was confirmed. When the direction of electric
polarization is reversed, the vector spin chirality as defined by ${\bf C}_{ij}
= {\bf S}_i \times {\bf S}_j$ ($i$ and $j$ being the neighboring spin sites) is
observed to be reversed, indicating that the spin-current model or the inverse
Dzyaloshinskii-Moriya mechanism is applicable even to this
$e_{\mathrm{g}}$-electron quantum-spin system. Differential scattering
intensity of polarized neutrons shows a large discrepancy from that expected
for the classical-spin $bc$-cycloidal structure, implying the effect of large
quantum fluctuation.


title: Metallicity and Physical Conditions in the Magellanic Bridge

abstract:
  We present a new analysis of the diffuse gas in the Magellanic Bridge (RA>3h)
based on HST/STIS E140M and FUSE spectra of 2 early-type stars lying within the
Bridge and a QSO behind it. We derive the column densities of HI (from
Ly\alpha), NI, OI, ArI, SiII, SII, and FeII of the gas in the Bridge. Using the
atomic species, we determine the first gas-phase metallicity of the Magellanic
Bridge, [Z/H]=-1.02+/-0.07 toward one sightline, and -1.7<[Z/H]<-0.9 toward the
other one, a factor 2 or more smaller than the present-day SMC metallicity.
Using the metallicity and N(HI), we show that the Bridge gas along our three
lines of sight is ~70-90% ionized, despite high HI columns, logN(HI)=19.6-20.1.
Possible sources for the ongoing ionization are certainly the hot stars within
the Bridge, hot gas (revealed by OVI absorption), and leaking photons from the
SMC and LMC. From the analysis of CII*, we deduce that the overall density of
the Bridge must be low (<0.03-0.1 cm^-3). We argue that our findings combined
with other recent observational results should motivate new models of the
evolution of the SMC-LMC-Galaxy system.


title: Chiral Corrections to Hyperon Axial Form Factors

abstract:
  We study the complete set of flavor changing hyperon axial current matrix
elements at small momentum transfer. Using partially quenched heavy baryon
chiral perturbation theory, we derive the chiral and momentum behavior of the
axial and induced pseudoscalar form factors. The meson pole contributions to
the latter posses a striking signal for chiral physics. We argue that the study
of hyperon axial matrix elements enables a systematic lattice investigation of
the efficacy of three flavor chiral expansions in the baryon sector. This can
be achieved by considering chiral corrections to SU(3) symmetry predictions,
and their partially quenched generalizations. In particular, despite the
presence of eight unknown low-energy constants, we are able to make
next-to-leading order symmetry breaking predictions for two linear combinations
of axial charges.


title: Non-Supersymmetric Attractors in Symmetric Coset Spaces

abstract:
  We present a method of constructing generic single-centered and
multi-centered extremal black hole solutions in a large class of 4D N=2
supergravities coupled to vector-multiplets with cubic prepotentials. The
method is applicable to models for which the 3D moduli spaces obtained via
c*-map are symmetric coset spaces. The attractor solutions are generated by
certain nilpotent elements in the coset algebra. We present explicit
computations in 4D N=2 supergravity coupled to one vector-multiplet, whose 3D
moduli space is the symmetric coset space G_{2(2)}/SL(2,R)^2. The
non-supersymmetric multi-centered black holes in this model are found to lack
the intricate moduli space of bound configurations that are typical of the
supersymmetric case.


title:
Multi-Cycle HST Treasury Program for STIS: Mapping the Galactic
  Environment of the Sun

abstract:
  Interstellar clouds form the cosmic "ecosystem" through which the Sun moves.
Understanding the physical properties of nearby interstellar material, in
sufficient detail to evaluate historical variations in the solar galactic
environment, requires a survey of ultraviolet interstellar absorption lines
towards stars within 20 pc with the STIS spectrometer. A complete survey would
yield ionization, temperature, density and velocity for nearby interstellar
clouds, and would require a large number of Hubble Space Telescope orbits
spaced over several cycles. This note was submitted as a "white paper" to the
Space Telescope Science Institute in support of multi-cycle treasury programs.


title: Dynamic stabilization of non-spherical bodies against unlimited collapse

abstract:
  We solve equations, describing in a simplified way the newtonian dynamics of
a selfgravitating nonrotating spheroidal body after loss of stability. We find
that contraction to a singularity happens only in a pure spherical collapse,
and deviations from the spherical symmetry stop the contraction by the
stabilising action of nonlinear nonspherical oscillations. A real collapse
happens after damping of the oscillations due to energy losses, shock wave
formation or viscosity. Detailed analysis of the nonlinear oscillations is
performed using a Poincar\'{e} map construction. Regions of regular and chaotic
oscillations are localized on this map.


title: Neutralino Dark Matter and Trilepton Searches in the MSSM

abstract:
  Searches for supersymmetry are among the most exciting physics goals at Run
II of the Tevatron. In particular, in supersymmetric models with light
charginos, neutralinos and sleptons, associated chargino--neutralino production
can potentially be observed as multi-lepton events with missing energy. We
discuss how, in the generic TeV-scale MSSM, the prospects for these
chargino-neutralino searches are impacted by cosmological considerations,
namely the neutralino relic abundance and direct detection limits. We also
discuss what an observation of chargino-neutralino production at the Tevatron
would imply for the prospects of future direct dark matter searches without
assuming specific patterns of supersymmetry breaking.


title: Giants on Deformed Backgrounds Part II: The Gauge Field Fluctuations

abstract:
  We study the full bosonic spectrum around giant and dual giant graviton
probes in exactly marginally deformed backgrounds. Considering supersymmetric
and non-supersymmetric three-parameter deformations of AdS_5 X S^5, we perform
a detailed analysis of small fluctuations for both the expanded D3-brane
configurations. In particular, we enhance the scalar spectra of frequencies
found in our previous paper hep-th/0609173 with the important contributions
brought by the gauge field fluctuations. The giant graviton case exhibits a
non-trivial coupling between scalar and vector modes driven by the deformation,
whose resolution yields to a universal correction of the undeformed spectrum.
On the other hand, dual giant vibrations turn out to be completely decoupled.
From our results one can also easily read the gauge field fluctuations in the
undeformed (dual) giant graviton scenario.


title:
Two Poisson structures invariant with respect to discrete transformation
  in the case of arbitrary semi-simple algebras

abstract:
  Two Poisson structures invariant with respect to discrete transformation of
the Maximal root in the case of arbitrary semi-simple algebras are presented in
explicit form. Thus the problem of construction of equations of n-wave
hierarchy in the case of arbitrary semi simple algebra is solved finally.


title: Functional BES equation

abstract:
  We give a realization of the Beisert, Eden and Staudacher equation for the
planar N=4 supersymetric gauge theory whichseems to be particularly useful to
study the strong coupling limit. We use a linearized version of the BES
equation as two coupled equations involving an auxiliary density function. We
write these equations in terms of the resolvents and we transform them into to
a system of functional, instead of integral, equations. We solve the functional
equations perturbatively in the strong coupling limit and reproduce the
recursive solution obtained by Basso, Korchemsky and Kotanski. The coefficients
of the strong coupling expansion are fixed by the analyticity properties obeyed
by the resolvents.


title: Modular Forms and Three Loop Superstring Amplitudes

abstract:
  We study a proposal of D'Hoker and Phong for the chiral superstring measure
for genus three. A minor modification of the constraints they impose on certain
Siegel modular forms leads to a unique solution. We reduce the problem of
finding these modular forms, which depend on an even spin structure, to finding
a modular form of weight 8 on a certain subgroup of the modular group. An
explicit formula for this form, as a polynomial in the even theta constants, is
given. We checked that our result is consistent with the vanishing of the
cosmological constant. We also verified a conjecture of D'Hoker and Phong on
modular forms in genus 3 and 4 using results of Igusa.


title:
Higgs production via gluon-gluon fusion with finite top mass beyond
  next-to-leading order

abstract:
  We present a computation of the cross section for inclusive Higgs production
in gluon-gluon fusion for finite values of the top mass in perturbative QCD to
all orders in the limit of high partonic center-of-mass energy. We show that at
NLO the high energy contribution accounts for most of the difference between
the result found with finite top mass and that obtained in the limit of
infinite top mass. We use our result to improve the known NNLO order result
obtained with infinite top mass. We estimate the effect of the high energy NNLO
top mass dependence on the K factor to be of the order of a few per cent.


title:
Supersymmetric U(1) Gauge Realization of the Dark Scalar Doublet Model
  of Radiative Neutrino Mass

abstract:
  Adding a second scalar doublet (eta^+,eta^0) and three neutral singlet
fermions N_{1,2,3} to the Standard Model of particle interactions with a new
Z_2 symmetry, it has been shown that Re(eta^0) or Im(eta^0) is a good
dark-matter candidate and seesaw neutrino masses are generated radiatively. A
supersymmetric U(1) gauge extension of this new idea is proposed, which
enforces the usual R parity of the Minimal Supersymmetric Standard Model, and
allows this new Z_2 symmetry to emerge as a discrete remnant.


title: Non-monotonic pseudo-gap in high-Tc cuprates

abstract:
  The mechanism of high temperature superconductivity is not resolved for so
long because the normal state of cuprates is not yet understood. Here we show
that the normal state pseudo-gap exhibits an unexpected non-monotonic
temperature dependence, which rules out the possibility to describe it by a
single mechanism such as superconducting phase fluctuations. Moreover, this
behaviour, being remarkably similar to the behaviour of the charge ordering gap
in the transition-metal dichalcogenides, completes the correspondence between
these two classes of compounds: the cuprates in the PG state and the
dichalcogenides in the incommensurate charge ordering state reveal virtually
identical spectra of one-particle excitations as function of energy, momentum
and temperature. These results suggest that the normal state pseudo-gap, which
was considered to be very peculiar to cuprates, seems to be a general complex
phenomenon for 2D metals. This may not only help to clarify the normal state
electronic structure of 2D metals but also provide new insight into electronic
properties of 2D solids where the metal-insulator and metal-superconductor
transitions are considered on similar basis as instabilities of particle-hole
and particle-particle interaction, respectively.


title:
The evolution of the photometric properties of Local Group dwarf
  spheroidal galaxies

abstract:
  We investigate the present-day photometric properties of the dwarf spheroidal
galaxies in the Local Group. From the analysis of their integrated colours, we
consider a possible link between dwarf spheroidals and giant ellipticals. From
the analysis of the V vs (B-V) plot, we search for a possible evolutionary link
between dwarf spheroidal galaxies (dSphs) and dwarf irregular galaxies (dIrrs).
By means of chemical evolution models combined with a spectro-photometric
model, we study the evolution of six Local Group dwarf spheroidal galaxies
(Carina, Draco, Sagittarius, Sculptor, Sextans and Ursa Minor). The chemical
evolution models, which adopt up-to-date nucleosynthesis from low and
intermediate mass stars as well as nucleosynthesis and energetic feedback from
supernovae type Ia and II, reproduce several observational constraints of these
galaxies, such as abundance ratios versus metallicity and the metallicity
distributions. The proposed scenario for the evolution of these galaxies is
characterised by low star formation rates and high galactic wind efficiencies.
Such a scenario allows us to predict integrated colours and magnitudes which
agree with observations. Our results strongly suggest that the first few Gyrs
of evolution, when the star formation is most active, are crucial to define the
luminosities, colours, and other photometric properties as observed today.
After the star formation epoch, the galactic wind sweeps away a large fraction
of the gas of each galaxy, which then evolves passively. Our results indicate
that it is likely that at a certain stage of their evolution, dSphs and dIrrs
presented similar photometric properties. However, after that phase, they
evolved along different paths, leading them to their currently disparate
properties.


title:
A new eight vertex model and higher dimensional, multiparameter
  generalizations

abstract:
  We study statistical models, specifically transfer matrices corresponding to
a multiparameter hierarchy of braid matrices of $(2n)^2\times(2n)^2$ dimensions
with $2n^2$ free parameters $(n=1,2,3,...)$. The simplest, $4\times 4$ case is
treated in detail. Powerful recursion relations are constructed giving the
dependence on the spectral parameter $\theta$ of the eigenvalues of the
transfer matrix explicitly at each level of coproduct sequence. A brief study
of higher dimensional cases ($n\geq 2$) is presented pointing out features of
particular interest. Spin chain Hamiltonians are also briefly presented for the
hierarchy. In a long final section basic results are recapitulated with
systematic analysis of their contents. Our eight vertex $4\times 4$ case is
compared to standard six vertex and eight vertex models.


title:
On the persistence of invariant curves for Fibered Holomorphic
  Transformations

abstract:
  We consider the problem of the persistence of invariant curves for analytical
fibered holomorphic transformations. We define a fibered rotation number
associated to an invariant curve. We show that an invariant curve with a
prescribed fibered rotation number persists under small perturbations on the
dynamics provided that the pair of rotation numbers verifies a Brjuno type
arithmetical condition.


title: Moduli spaces of framed instanton sheaves on projective spaces

abstract:
  This paper has been withdraw. A fully revised version with two new co-authors
has been posted: "ADHM construction of perverse instanton sheaves",
arXiv:1201.5657.


title: Interstellar dust evolution in galaxies of different morphological types

abstract:
  We study interstellar dust evolution in various environments by means of
chemical evolution models for galaxies of different morphological types. We
start from the formalism developed by Dwek (1998) to study dust evolution in
the solar neighbourhood and extend it to ellipticals and dwarf irregular
galaxies, showing how the evolution of the dust production rates and of the
dust fractions depend on the galactic star formation history. The observed dust
fractions observed in the solar neighbourhood can be reproduced by assuming
that dust destruction depends the condensation temperatures T_c of the
elements. In elliptical galaxies, type Ia SNe are the major dust factories in
the last 10 Gyr. With our models, we successfully reproduce the dust masses
observed in local ellipticals (~10^6 M_sun) by means of recent FIR and SCUBA
observations. We show that dust is helpful in solving the iron discrepancy
observed in the hot gaseous halos surrounding local ellipticals. In dwarf
irregulars, we show how a precise determination of the dust depletion pattern
could be useful to put solid constraints on the dust condensation efficiencies.
Our results will be helpful to study the spectral properties of dust grains in
local and distant galaxies.


title: Note on a sigma model connection with instanton dynamics

abstract:
  It is well known that the instanton approach to QCD generates an effective
term which looks like a three flavor determinant of quark bilinears. This has
the right behavior to explain the unusual mass and mixing of the $\eta(958)$
meson, as is often simply illustrated with the aid of a linear SU(3) sigma
model. It is less well known that the instanton analysis generates another term
which has the same transformation property but does not have a simple
interpretation in terms of this usual linear sigma model. Here we point out
that this term has an interpretation in a generalized linear sigma model
containing two chiral nonets. The second chiral nonet is taken to correspond to
mesons having two quarks and two antiquarks in their makeup. The generalized
model seems to be useful for learning about the spectrum of low lying scalar
mesons which have been emerging in the last few years. The physics of the new
term is shown to be related to the properties of an "excited" $\eta'$ state
present in the generalized model and for which there are some experimental
candidates.


title: Topologically Trivial Legendrian Knots

abstract:
  The paper deals with topologically trivial Legendrian knots in tight and
overtwisted contact 3-manifolds. The first part contains a thorough exposition
of the proof of the classification of topologically trivial Legendrian knots
(i.e. Legendrian knots bounding embedded 2-disks) in tight contact 3-manifolds.
This part was essentially written more than 10 years ago, but only a short
version, without the detailed proofs, was published (in CRM Proc. Lecture
Notes, Vol. 15, 1998). That paper also briefly discussed the overtwisted case.
  The final part of the present paper contains a more systematic discussion of
Legendrian knots in overtwisted contact manifolds, and in particular, gives the
coarse classification (i.e. classification up to a global contactomorphism) of
topologically trivial Legendrian knots in overtwisted contact S^3.


title:
Betti number bounds for fewnomial hypersurfaces via stratified Morse
  theory

abstract:
  We use stratified Morse theory for a manifold with corners to give a new
bound for the sum of the Betti numbers of a hypersurface in R^n_> defined by a
polynomial with n+l+1 terms.


title:
Penalized Clustering of Large Scale Functional Data with Multiple
  Covariates

abstract:
  In this article, we propose a penalized clustering method for large scale
data with multiple covariates through a functional data approach. In the
proposed method, responses and covariates are linked together through
nonparametric multivariate functions (fixed effects), which have great
flexibility in modeling a variety of function features, such as jump points,
branching, and periodicity. Functional ANOVA is employed to further decompose
multivariate functions in a reproducing kernel Hilbert space and provide
associated notions of main effect and interaction. Parsimonious random effects
are used to capture various correlation structures. The mixed-effect models are
nested under a general mixture model, in which the heterogeneity of functional
data is characterized. We propose a penalized Henderson's likelihood approach
for model-fitting and design a rejection-controlled EM algorithm for the
estimation. Our method selects smoothing parameters through generalized
cross-validation. Furthermore, the Bayesian confidence intervals are used to
measure the clustering uncertainty. Simulation studies and real-data examples
are presented to investigate the empirical performance of the proposed method.
Open-source code is available in the R package MFDA.


title:
Search for production of single top quarks via $tcg$ and $tug$
  flavor-changing neutral current couplings

abstract:
  We search for the production of single top quarks via flavor-changing neutral
current couplings of a gluon to the top quark and a charm ($c$) or up ($u$)
quark. We analyze 230 pb$^{-1}$ of lepton + jets data from $\ppbar$ collisions
at a center of mass energy of 1.96 TeV collected by the D0 detector at the
Fermilab Tevatron Collider. We observe no significant deviation from standard
model predictions, and hence set upper limits on the anomalous coupling
parameters $\kappacLambda$ and $\kappauLambda$, where $\kappag$ define the
strength of $tcg$ and $tug$ couplings, and $\Lambda$ defines the scale of new
physics. The limits at 95% C.L. are: $\kappacLambda < 0.15 \rm TeV^{-1}$ and
$\kappauLambda < 0.037 \rm TeV^{-1}$.


title: Non-renormalization for the Liouville wave function

abstract:
  Using an exact functional method, within the framework of the gradient
expansion for the Liouville effective action, we show that the kinetic term for
the Liouville field is not renormalized.


title: Measuring Star Formation in Local and Distant Galaxies

abstract:
  I review measurements of star formation in nearby galaxies in the UV-to-FIR
wavelength range, and discuss their impact on SFR determinations in
intermediate and high redshift galaxy populations. Existing and upcoming
facilities will enable precise cross-calibrations among the various indicators,
thus bringing them onto a common scale.


title:
Freud's Identity of Differential Geometry, the Einstein-Hilbert
  Equations and the Vexatious Problem of the Energy-Momentum Conservation in GR

abstract:
  We reveal in a rigorous mathematical way using the theory of differential
forms, here viewed as sections of a Clifford bundle over a Lorentzian manifold,
the true meaning of Freud's identity of differential geometry discovered in
1939 (as a generalization of results already obtained by Einstein in 1916) and
rediscovered in disguised forms by several people. We show moreover that
contrary to some claims in the literature there is not a single (mathematical)
inconsistency between Freud's identity (which is a decomposition of the
Einstein indexed 3-forms in two gauge dependent objects) and the field
equations of General Relativity. However, as we show there is an obvious
inconsistency in the way that Freud's identity is usually applied in the
formulation of energy-momentum "conservation laws" in GR. In order for this
paper to be useful for a large class of readers (even those ones making a first
contact with the theory of differential forms) all calculations are done with
all details (disclosing some of the "tricks of the trade" of the subject).


title: Terrestrial Planet Formation in Extra-Solar Planetary Systems

abstract:
  Terrestrial planets form in a series of dynamical steps from the solid
component of circumstellar disks. First, km-sized planetesimals form likely via
a combination of sticky collisions, turbulent concentration of solids, and
gravitational collapse from micron-sized dust grains in the thin disk midplane.
Second, planetesimals coalesce to form Moon- to Mars-sized protoplanets, also
called "planetary embryos". Finally, full-sized terrestrial planets accrete
from protoplanets and planetesimals. This final stage of accretion lasts about
10-100 Myr and is strongly affected by gravitational perturbations from any gas
giant planets, which are constrained to form more quickly, during the 1-10 Myr
lifetime of the gaseous component of the disk. It is during this final stage
that the bulk compositions and volatile (e.g., water) contents of terrestrial
planets are set, depending on their feeding zones and the amount of radial
mixing that occurs. The main factors that influence terrestrial planet
formation are the mass and surface density profile of the disk, and the
perturbations from giant planets and binary companions if they exist. Simple
accretion models predicts that low-mass stars should form small, dry planets in
their habitable zones. The migration of a giant planet through a disk of rocky
bodies does not completely impede terrestrial planet growth. Rather, "hot
Jupiter" systems are likely to also contain exterior, very water-rich
Earth-like planets, and also "hot Earths", very close-in rocky planets. Roughly
one third of the known systems of extra-solar (giant) planets could allow a
terrestrial planet to form in the habitable zone.


title: Quantum Error Correction Code in the Hamiltonian Formulation

abstract:
  The Hamiltonian model of quantum error correction code in the literature is
often constructed with the help of its stabilizer formalism. But there have
been many known examples of nonadditive codes which are beyond the standard
quantum error correction theory using the stabilizer formalism. In this paper,
we suggest the other type of Hamiltonian formalism for quantum error correction
code without involving the stabilizer formalism, and explain it by studying the
Shor nine-qubit code and its generalization. In this Hamiltonian formulation,
the unitary evolution operator at a specific time is a unitary basis
transformation matrix from the product basis to the quantum error correction
code. This basis transformation matrix acts as an entangling quantum operator
transforming a separate state to an entangled one, and hence the entanglement
nature of the quantum error correction code can be explicitly shown up.
Furthermore, as it forms a unitary representation of the Artin braid group, the
quantum error correction code can be described by a braiding operator.
Moreover, as the unitary evolution operator is a solution of the quantum
Yang--Baxter equation, the corresponding Hamiltonian model can be explained as
an integrable model in the Yang--Baxter theory. On the other hand, we
generalize the Shor nine-qubit code and articulate a topic called quantum error
correction codes using Greenberger-Horne-Zeilinger states to yield new
nonadditive codes and channel-adapted codes.


title: Naturally Speaking: The Naturalness Criterion and Physics at the LHC

abstract:
  A non-technical discussion of the naturalness criterion and its implications
for new physics searches at the LHC. To be published in the book "LHC
Perspectives", edited by G. Kane and A. Pierce.


title: CMB Anisotropies: Their Discovery and Utilization

abstract:
  This article is a written and modified version of a talk presented at the
conference `A Century of Cosmology' held at San Servolo, Venice, Italy, in
August 2007. The talk focuses on some of the cosmology history leading to the
discovery and exploitation of Cosmic Microwave Background (CMB) Radiation
anisotropies. We have made tremendous advances first in the development of the
techniques to observe these anisotropies and in observing and interpreting them
to extract their contained cosmological information. CMB anisotropies are now a
cornerstone in our understanding of the cosmos and our future progress in the
field. This is an outcome that Dennis Sciama hoped for and encouraged.


title: Modern space-time and undecidability

abstract:
  The picture of space-time that Minkowski created in 1907 has been followed by
two important developments in physics not contained in the original picture:
general relativity and quantum mechanics. We will argue that the use of
concepts of those theories to construct space-time implies conceptual
modifications in quantum mechanics. In particular one can construct a viable
picture of quantum mechanics without a reduction process that has outcomes
equivalent to a picture with a reduction process. One therefore has two
theories that are entirely equivalent experimentally but profoundly different
in the description of reality they give. This introduces a fundamental level of
undecidability in physics of a kind that has not been present before. We
discuss some of the implications.


title: Exts and Vertex Operators

abstract:
  The direct product of two Hilbert schemes of the same surface has natural
K-theory classes given by the alternating Ext groups between the two ideal
sheaves in question, twisted by a line bundle. We express the Chern classes of
these virtual bundles in terms of Nakajima operators.


title: Asymptotic dynamics of attractive-repulsive swarms

abstract:
  We classify and predict the asymptotic dynamics of a class of swarming
models. The model consists of a conservation equation in one dimension
describing the movement of a population density field. The velocity is found by
convolving the density with a kernel describing attractive-repulsive social
interactions. The kernel's first moment and its limiting behavior at the origin
determine whether the population asymptotically spreads, contracts, or reaches
steady-state. For the spreading case, the dynamics approach those of the porous
medium equation. The widening, compactly-supported population has edges that
behave like traveling waves whose speed, density and slope we calculate. For
the contracting case, the dynamics of the cumulative density approach those of
Burgers' equation. We derive an analytical upper bound for the finite blow-up
time after which the solution forms one or more $\delta$-functions.


title: Cohomology of Frobenius Algebras and the Yang-Baxter Equation

abstract:
  A cohomology theory for multiplications and comultiplications of Frobenius
algebras is developed in low dimensions in analogy with Hochschild cohomology
of bialgebras based on deformation theory. Concrete computations are provided
for key examples.
  Skein theoretic constructions give rise to solutions to the Yang-Baxter
equation using multiplications and comultiplications of Frobenius algebras, and
2-cocycles are used to obtain deformations of R-matrices thus obtained.


title:
Imaging Mechanism of Piezoresponse Force Microscopy in Capacitor
  Structures

abstract:
  The image formation mechanism in Piezoresponse Force Microscopy (PFM) of
capacitor structures is analyzed. We demonstrate that the spatial resolution is
a bilinear function of film and top electrode thicknesses, and derive the
corresponding analytical expressions. For many perovskites, the opposite
contributions of d31 and d33 components can result in anomalous domain wall
profiles. This analysis establishes the applicability limits of PFM for
polarization dynamics studies in capacitors, and applies to other structural
probes, including focused X-ray studies of capacitor structures.


title: Rapid variability in TeV blazars: the case of PKS 2155-304

abstract:
  Recent Cherenkov observations of BL Lac objects showed that the TeV flux of
PKS 2155-304 changed by a factor 2 in just 3-5 minutes. This fast variability
can be accounted for if the emitting region is moving with a bulk Lorentz
factor Gamma~50 and a similar relativistic Doppler factor. If this Gamma is
adopted, several models can fit the data, but, irrespective of the chosen
model, the jet is matter dominated. The Doppler factor requires viewing angles
of the order of 1 degree or less: if the entire jet is as narrow as this, then
we have problems with current unification schemes. This suggests that there are
small active regions, inside a larger jet, moving faster than the rest of the
plasma, occasionally pointing at us. Coordinated X-ray/TeV variability can
discriminate between the different scenarios.


title: The Hot Gas Halos of Galaxies in Groups

abstract:
  We use Chandra observations of 13 nearby groups of galaxies to investigate
the hot gas content of their member galaxies. We find that a large fraction of
near-IR bright, early-type galaxies in groups have extended X-ray emission,
indicating that they retain significant hot gas halos even in these dense
environments. In particular, we detect hot gas halos in ~80% of L_K > L_star
galaxies. We do not find a significant difference in the L_K-L_X relation for
detected group and cluster early-type galaxies. However, we detect X-ray
emission from a significantly higher fraction of galaxies brighter than L_star
in groups compared to clusters, indicating that a larger fraction of galaxies
in clusters experience significant stripping of their hot gas. In addition,
group and cluster galaxies appear to be X-ray faint compared to field galaxies,
though a Chandra based field sample is needed to confirm this result. The
near-IR bright late-types galaxies in clusters and groups appear to follow the
L_K-L_X relation for early-type galaxies, while near-IR fainter late-type
galaxies are significantly more X-ray luminous than this relation likely due to
star formation. Finally, we find individual examples of ongoing gas stripping
of group galaxies. One galaxy shows a 40-50 kpc X-ray tail, and two merging
galaxy systems show tidal bridges/tails of X-ray emission. Therefore, stripping
of hot galactic gas through both ram pressure and tidal forces does occur in
groups and clusters, but the frequency or efficiency of such events must be
moderate enough to allow hot gas halos in a large fraction of bright galaxies
to survive even in group and cluster cores.


title: Cosmological Information in the Gravitational Lensing of Pregalactic HI

abstract:
  We study the constraints which the next generation of radio telescopes could
place on the nature of dark energy, dark matter and inflation by studying the
gravitational lensing of high redshift 21 cm emission, and we compare with the
constraints obtainable from wide-angle surveys of galaxy lensing. If the
reionization epoch is effectively at z ~ 8 or later, very large amounts of
cosmological information will be accessible to telescopes like SKA and LOFAR.
We use simple characterizations of reionization history and of proposed
telescope designs to investigate how well the two-dimensional convergence power
spectrum, the three-dimensional matter power spectrum, the evolution of the
linear growth function, and the standard cosmological parameters can be
measured from radio data. The power spectra can be measured accurately over a
wide range of wavenumbers at z ~ 2, and the evolution in the cosmic energy
density can be probed from z ~ 0.5 to z ~ 7. This results in a characterization
of the shape of the power spectra (i.e. of the nature of dark matter and of
inflationary structure generation) which is potentially more precise than that
obtained from galaxy lensing surveys. On the other hand, the dark energy
parameters in their conventional parametrization (Omega_Lambda, w_o, w_a) are
somewhat less well constrained by feasible 21 cm lensing surveys than by an
all-sky galaxy lensing survey although a 21 cm surveys might be more powerful
than galaxy surveys for constraining models with "early" dark energy. Overall,
the best constraints come from combining surveys of the two types. This results
in extremely tight constraints on dark matter and inflation, and improves
constraints on dark energy, as judged by the standard figure of merit, by more
than an order of magnitude over either survey alone.


title:
Effects of a Primordial Magnetic Field on Low and High Multipoles of the
  CMB

abstract:
  The existence of a primordial magnetic field (PMF) would affect both the
temperature and polarization anisotropies of the cosmic microwave background
(CMB). It also provides a plausible explanation for the possible disparity
between observations and theoretical fits to the CMB power spectrum. Here we
report on calculations of not only the numerical CMB power spectrum from the
PMF, but also the correlations between the CMB power spectrum from the PMF and
the primary curvature perturbations. We then deduce a precise estimate of the
PMF effect on all modes of perturbations. We find that the PMF affects not only
the CMB TT and TE modes on small angular scales, but also on large angular
scales. The introduction of a PMF leads to a better fit to the CMB power
spectrum for the higher multipoles, and the fit at lowest multipoles can be
used to constrain the correlation of the PMF with the density fluctuations for
large negative values of the spectral index. Our prediction for the BB mode for
a PMF average field strength $|B_\lambda| =4.0$ nG is consistent with the upper
limit on the BB mode deduced from the latest CMB observations. We find that the
BB mode is dominated by the vector mode of the PMF for higher multipoles. We
also show that by fitting the complete power spectrum one can break the
degeneracy between the PMF amplitude and its power spectral index.


title:
Transient Emissions from Radio-Active Stars: Implications for Wide-Field
  Radio Surveys

abstract:
  Variability is a common characteristic of magnetically active stars. Flaring
variability is usually interpreted as the observable consequence of transient
magnetic reconnection processes happening in the stellar outer atmosphere.
Stellar flares have been observed now across 11 decades in
wavelength/frequency/energy; such a large span implies that a range of physical
processes takes place during such events. Despite the fact that stellar radio
flares have long been recognized and studied, key unanswered questions remain.
I will highlight what, in my opinion, are some of these questions. I will also
describe recent results on stellar flare emissions at radio wavelengths,
discussing the nature of coherent and incoherent emissions and the prospects of
wide-field radio imaging telescopes for studying such events.


title: A generalized Cahn-Hilliard equation for biological applications

abstract:
  Recently we considered a stochastic discrete model which describes fronts of
cells invading a wound \cite{KSS}. In the model cells can move, proliferate,
and experience cell-cell adhesion. In this work we focus on a continuum
description of this phenomenon by means of a generalized Cahn-Hilliard equation
(GCH) with a proliferation term. As in the discrete model, there are two
interesting regimes. For subcritical adhesion, there are propagating "pulled"
fronts, similarly to those of Fisher-Kolmogorov equation. The problem of front
velocity selection is examined, and our theoretical predictions are in a good
agreement with a numerical solution of the GCH equation. For supercritical
adhesion, there is a nontrivial transient behavior, where density profile
exhibits a secondary peak. To analyze this regime, we investigated relaxation
dynamics for the Cahn-Hilliard equation without proliferation. We found that
the relaxation process exhibits self-similar behavior. The results of continuum
and discrete models are in a good agreement with each other for the different
regimes we analyzed.


title: Hypergames and full completeness for system F (rough draft)

abstract:
  This paper reviews the fully complete hypergames model of system $F$,
presented a decade ago in the author's thesis. Instantiating type variables is
modelled by allowing ``games as moves''. The uniformity of a quantified type
variable $\forall X$ is modelled by copycat expansion: $X$ represents an
unknown game, a kind of black box, so all the player can do is copy moves
between a positive occurrence and a negative occurrence of $X$.
  This presentation is based on slides for a talk entitled ``Hypergame
semantics: ten years later'' given at `Games for Logic and Programming
Languages', Seattle, August 2006.


title:
Control of atomic decay rates via manipulation of reservoir mode
  frequencies

abstract:
  We analyse the problem of a two-level atom interacting with a time-dependent
dissipative environment modelled by a bath of reservoir modes. In the model of
this paper the principal features of the reservoir structure remain constant in
time, but the microscopic structure does not. In the context of an atom in a
leaky cavity this corresponds to a fixed cavity and a time-dependent external
bath. In this situation we show that by chirping the reservoir modes
sufficiently fast it is possible to inhibit, or dramatically enhance the decay
of the atomic system, even though the gross reservoir structure is fixed. Thus
it is possible to extract energy from a cavity-atom system faster than the
empty cavity rate. Similar, but less dramatic effects are possible for moderate
chirps where partial trapping of atomic population is also possible.


title: A new proof of Roth's theorem on arithmetic progressions

abstract:
  We present a proof of Roth's theorem that follows a slightly different
structure to the usual proofs, in that there is not much iteration. Although
our proof works using a type of density increment argument (which is typical of
most proofs of Roth's theorem), we do not pass to a progression related to the
large Fourier coefficients of our set (as most other proofs of Roth do).
Furthermore, in our proof, the density increment is achieved through an
application of a quantitative version of Varnavides's theorem, which is perhaps
unexpected.


title: Hexadecapole Approximation in Planetary Microlensing

abstract:
  The frequency of microlensing planet detections, particularly in
difficult-to-model high-magnification events, is increasing. Their analysis can
require tens of thousands of processor hours or more, primarily because of the
high density and high precision of measurements whose modeling requires
time-consuming finite-source calculations. I show that a large fraction of
these measurements, those that lie at least one source diameter from a caustic
or the extension from a cusp, can be modeled using a very simple hexadecapole
approximation, which is one to several orders of magnitude faster than
full-fledged finite-source calculations. Moreover, by restricting the regions
that actually require finite-source calculations to a few isolated `caustic
features', the hexadecapole approximation will, for the first time, permit the
powerful `magnification-map' approach to be applied to events for which the
planet's orbital motion is important.


title:
Impact of Orbital Eccentricity on the Detection of Transiting Extrasolar
  Planets

abstract:
  For extrasolar planets with orbital periods, P>10 days, radial velocity
surveys find non-circular orbital eccentricities are common, <e>~0.3. Future
surveys for extrasolar planets using the transit technique will also have
sensitivity to detect these longer period planets. Orbital eccentricity affects
the detection of extrasolar planets using the transit technique in two opposing
ways: an enhancement in the probability for the planet to transit near
pericenter and a reduction in the detectability of the transit due to a shorter
transit duration. For an eccentricity distribution matching the currently known
extrasolar planets with P>10 day, the probability for the planet to transit is
~1.25 times higher than the equivalent circular orbit and the average transit
duration is ~0.88 times shorter than the equivalent circular orbit. These two
opposing effects nearly cancel for an idealized field transit survey with
independent photometric measurements that are dominated by Poisson noise. The
net effect is a modest ~4% increase in the transiting planet yield compared to
assuming all planets have circular orbits. When intrinsic variability of the
star or correlated photometric measurements are the dominant source of noise,
the transit detectability is independent of the transit duration. In this case
the transit yield is ~25% higher than that predicted under the assumption of
circular orbits. Since the Kepler search for Earth-sized planets in the
habitable zone of a Solar-type star is limited by intrinsic variability, the
Kepler mission is expected to have a ~25% higher planet yield than that
predicted for circular orbits if the Earth-sized planets have an orbital
eccentricity distribution similar to the currently known Jupiter-mass planets.


title: Mean-field stationary state of a Bose gas at a Feshbach resonance

abstract:
  We study the steady state of a zero-temperature Bose gas near a Feshbach or
photoassociation resonance using a two-channel mean-field model that
incorporates atomic and molecular condensates, as well as correlated atom pairs
originating from dissociation of molecules into pairs of atoms. We start from a
many-body Hamiltonian for atom-molecule conversion, and derive the time
dependent version of the mean-field theory. The stationary solution of the time
dependent model is rendered unique with an approximation that entails that all
noncondensate atoms are correlated, as if emerging from dissociation of
molecules. The steady state is solved numerically, but limiting cases are also
found analytically. The system has a phase transition in which the atomic
condensate emerges in a nonanalytic fashion. We quantify the scaling of the
observable quantities, such as fractions of atomic and molecular condensates,
with the detuning and the atom-molecule conversion strength. Qualitatively, the
dependence on detuning rounds out with increasing coupling strength. A study of
the thermodynamics shows that the pressure of the atom-molecule system is
negative, even on the molecule side of the resonance. This indicates the
possibility of mechanical instability.


title:
Intrinsic Cutoff and Acausality for Massive Spin 2 Fields Coupled to
  Electromagnetism

abstract:
  We couple a massive spin 2 particle to electromagnetism. By introducing new,
redundant degrees of freedom using the Stueckelberg formalism, we extract an
intrinsic, model independent UV cutoff of the effective field theory describing
this system. The cutoff signals both the onset of a strongly interacting
dynamical regime and a finite size for the spin 2 particle. We show that the
existence of a cutoff is strictly connected to other pathologies of interacting
high-spin fields, such as the Velo-Zwanziger acausality. We also briefly
comment on implications of this result for the detection of high spin states
and on its possible generalization to arbitrary spin.


title:
Non-Realizable Minimal Vertex Triangulations of Surfaces: Showing
  Non-Realizability using Oriented Matroids and Satisfiability Solvers

abstract:
  We show that no minimal vertex triangulation of a closed, connected,
orientable 2-manifold of genus 6 admits a polyhedral embedding in R^3. We also
provide examples of minimal vertex triangulations of closed, connected,
orientable 2-manifolds of genus 5 that do not admit any polyhedral embeddings.
We construct a new infinite family of non-realizable triangulations of
surfaces. These results were achieved by transforming the problem of finding
suitable oriented matroids into a satisfiability problem. This method can be
applied to other geometric realizability problems, e.g. for face lattices of
polytopes.


title:
Anomalous Momentum States, Non-Specular Reflections, and Negative
  Refraction of Phase-Locked, Second Harmonic Pulses

abstract:
  We simulate and discuss novel spatio-temporal propagation effects that relate
specifically to pulsed, phase-mismatched second harmonic generation in a
negative index material having finite length. Using a generic Drude model for
the dielectric permittivity and magnetic permeability, the fundamental and
second harmonic frequencies are tuned so that the respective indices of
refraction are negative for the pump and positive for the second harmonic
signal. A phase-locking mechanism causes part of the second harmonic signal
generated at the entry surface to become trapped and dragged along by the pump
and to refract negatively, even though the index of refraction at the second
harmonic frequency is positive. These circumstances culminate in the creation
of an anomalous state consisting of a forward-moving second harmonic wave
packet that has negative wave vector and momentum density, which in turn leads
to non-specular reflections at intervening material interfaces. The
forward-generated second harmonic signal trapped under the pump pulse
propagates forward, but has all the attributes of a reflected pulse, similar to
its twin counterpart generated at the surface and freely propagating backward
away from the interface. This describes a new state of negative refraction,
associated with nonlinear frequency conversion and parametric processes,
whereby a beam generated at the interface can refract negatively even though
the index of refraction at that wavelength is positive.


title:
Optical interferometric observations of Theta 1 Orionis C from NPOI and
  implications for the system orbit

abstract:
  With the Navy Prototype Optical Interferometer (NPOI), the binary system
Theta 1 Orionis C, the most massive member of the Trapezium, was spatially
resolved over a time period extending from February 2006 to March 2007. The
data show significant orbital motion over the 14 months, and, after combining
the NPOI data with previous measurements of the system from the literature, the
observations span 10 years of the orbit. Our results indicate that the
secondary did not experience an unusually close periastron passage this year,
in contradiction to the prediction of a recently published, highly eccentric
~11 year orbit. Future observations of this source will be required to improve
the orbital solution. Possible implications of the results in terms of system
distance are discussed, although a main conclusion of this work is that a
definitive orbit solution will require more time to obtain sufficient phase
coverage, and that the interaction effects expected at periastron did not occur
in 2007.