title: A Linear Equation for Wilson Loops

abstract:
  The Makeenko-Migdal loop equation is non-linear and first order in the area
derivative, but we show that for simple loops in QCD$_2$ it is possible to
reformulate this equation as a linear equation with second order derivatives.
This equation is a bound state Schr\"odinger equation with a three dimensional
Coulomb potential. Thus, loop dynamics leads to a surprising new picture of
confinement, where this phenomenon is due to a (bound state) localization in
loop space, with the Wilson loops decaying exponentially outside a
characteristic radius.


title: GRB neutrino detection via time profile stacking

abstract:
  A method is presented for the identification of high-energy neutrinos from
gamma ray bursts by means of a large-scale neutrino telescope. The procedure
makes use of a time profile stacking technique of observed neutrino induced
signals in correlation with satellite observations. By selecting a rather wide
time window, a possible difference between the arrival times of the gamma and
neutrino signals may also be identified. This might provide insight in the
particle production processes at the source. By means of a toy model it will be
demonstrated that a statistically significant signal can be obtained with a
km$^{3}$-scale neutrino telescope on a sample of 500 gamma ray bursts for a
signal rate as low as 1 detectable neutrino for 3% of the bursts.


title: Lagrangian reductive structures on gauge-natural bundles

abstract:
  A reductive structure is associated here with Lagrangian canonically defined
conserved quantities on gauge-natural bundles. Parametrized transformations
defined by the gauge-natural lift of infinitesimal principal automorphisms
induce a variational sequence such that the generalized Jacobi morphism is
naturally self-adjoint. As a consequence, its kernel defines a reductive split
structure on the relevant underlying principal bundle.


title:
Field dependence of the quantum ground state in the Shastry-Sutherland
  system SrCu$_2$(BO$_3$)$_2$

abstract:
  We present magnetic torque measurements on the Shastry-Sutherland quantum
spin system SrCu$_2$(BO$_3$)$_2$ in fields up to 31 T and temperatures down to
50 mK. A new quantum phase is observed in a 1 T field range above the 1/8
plateau, in agreement with recent NMR results. Since the presence of the DM
coupling precludes the existence of a true Bose-Einstein condensation and the
formation of a supersolid phase in SrCu$_2$(BO$_3$)$_2$, the exact nature of
the new phase in the vicinity of the plateau remains to be explained.
Comparison between magnetization and torque data reveals a huge contribution of
the Dzyaloshinskii-Moriya interaction to the torque response. Finally, our
measurements demonstrate the existence of a supercooling due to adiabatic
magnetocaloric effects in pulsed field experiments.


title:
Photometric Properties and Scaling Relations of Early Type Brightest
  Cluster Galaxies

abstract:
  We investigate the photometric properties of the early type Brightest Cluster
Galaxies (BCGs) using a carefully selected sample of 85 BCGs from the C4
cluster catalogue with redshift less than 0.1. We perform accurate background
subtractions, and surface photometry for these BCGs to 25 $\magsec$ in the
Sloan $r$-band. By quantitatively analysing the gradient of the Petrosian
profiles of BCGs, we find that a large fraction of BCGs have extended stellar
envelopes in their outskirts; more luminous BCGs tend to have more extended
stellar halos that are likely connected with mergers. A comparison sample of
elliptical galaxies was chosen with similar apparent magnitude and redshift
ranges, for which the same photometric analysis procedure is applied. We find
that BCGs have steeper size-luminosity ($R \propto L^\alpha$) and Faber-Jackson
($L \propto \sigma^\beta$) relations than the bulk of early type galaxies.
Furthermore, the power-law indices ($\alpha$ and $\beta$) in these relations
increase as the isophotal limits become deeper. For isophotal limits from 22 to
25 $\magsec$, BCGs are usually larger than the bulk of early type galaxies, and
a large fraction ($\sim 49%$) of BCGs have disky isophotal shapes. The
differences in the scaling relations are consistent with a scenario where the
dynamical structure and formation route of BCGs may be different from the bulk
of early type galaxies, in particular dry (dissipationless) mergers may play a
more important role in their formation; we highlight several possible dry
merger candidates in our sample.


title: Galois actions on homotopy groups

abstract:
  We study the Galois actions on the l-adic schematic and Artin-Mazur homotopy
groups of algebraic varieties. For proper varieties of good reduction over a
local field K, we show that the l-adic schematic homotopy groups are mixed
representations explicitly determined by the Galois action on cohomology of
Weil sheaves, whenever l is not equal to the residue characteristic p of K. For
quasi-projective varieties of good reduction, there is a similar
characterisation involving the Gysin spectral sequence. When l=p, a slightly
weaker result is proved by comparing the crystalline and p-adic schematic
homotopy types. Under favourable conditions, a comparison theorem transfers all
these descriptions to the Artin-Mazur homotopy groups.


title: Precision Electroweak Measurements and Constraints on the Standard Model

abstract:
  This note presents constraints on Standard Model parameters using published
and preliminary precision electroweak results measured at the electron-positron
colliders LEP and SLC. The results are compared with precise electroweak
measurements from other experiments, notably CDF and D{\O}at the Tevatron.
Constraints on the input parameters of the Standard Model are derived from the
results obtained in high-$Q^2$ interactions, and used to predict results in
low-$Q^2$ experiments, such as atomic parity violation, M{\o}ller scattering,
and neutrino-nucleon scattering.


title:
Shot noise and tunnel magnetoresistance in multilevel quantum dots:
  Effects of cotunneling

abstract:
  Spin-dependent transport through a multilevel quantum dot weakly coupled to
ferromagnetic leads is analyzed theoretically by means of the real-time
diagrammatic technique. Both the sequential and cotunneling processes are taken
into account, which makes the results on tunnel magnetoresistance (TMR) and
shot noise applicable in the whole range of relevant bias and gate voltages.
Suppression of the TMR due to inelastic cotunneling and super-Poissonian shot
noise have been found in some of the Coulomb blockade regions. Furthermore, in
the Coulomb blockade regime there is an additional contribution to the noise
due to bunching of cotunneling processes involving the spin-majority electrons.
On the other hand, in the sequential tunneling regime TMR oscillates with the
bias voltage, while the current noise is generally sub-Poissonian.


title:
Energy Level Lifetimes in the Single-Molecule Magnet Fe_8 : Experiments
  and Simulations

abstract:
  We present pump-probe measurements on the single-molecule magnet Fe_8 with
microwave pulses having a length of several nanoseconds. The microwave
radiation in the experiments is located in the frequency range between 104 GHz
and 118 GHz. The dynamics of the magnetization of the single Fe_8 crystal is
measured using micrometer-sized Hall sensors. This technique allows us to
determine the level lifetimes of excited spin states, that are found to be in
good agreement with theoretical calculations. The theory, to which we compare
our experimental results, is based on a general spin-phonon coupling formalism,
which involves spin transitions between nearest and next-nearest energy levels.
We show that good agreement between theory and experiments is only obtained
when using both the Delta m_S = +-1 transition as well as Delta m_S = +-2,
where Delta m_S designates a change in the spin quantum number m_S. Temperature
dependent studies of the level lifetimes of several spin states allow us
finally to determine experimentally the spin-phonon coupling constants.


title:
Dimensionality Reduction and Reconstruction using Mirroring Neural
  Networks and Object Recognition based on Reduced Dimension Characteristic
  Vector

abstract:
  In this paper, we present a Mirroring Neural Network architecture to perform
non-linear dimensionality reduction and Object Recognition using a reduced
lowdimensional characteristic vector. In addition to dimensionality reduction,
the network also reconstructs (mirrors) the original high-dimensional input
vector from the reduced low-dimensional data. The Mirroring Neural Network
architecture has more number of processing elements (adalines) in the outer
layers and the least number of elements in the central layer to form a
converging-diverging shape in its configuration. Since this network is able to
reconstruct the original image from the output of the innermost layer (which
contains all the information about the input pattern), these outputs can be
used as object signature to classify patterns. The network is trained to
minimize the discrepancy between actual output and the input by back
propagating the mean squared error from the output layer to the input layer.
After successfully training the network, it can reduce the dimension of input
vectors and mirror the patterns fed to it. The Mirroring Neural Network
architecture gave very good results on various test patterns.


title: Proof of the Somos-4 Hankel Determinants Conjecture

abstract:
  By considering the fundamental equation $x=y-y^2=z-z^3$, Somos conjectured
that the Hankel determinants for the generating series $y(z)$ are the Somos-4
numbers. We prove this conjecture by using the quadratic transformation for
Hankel determinants of Sulanke and Xin.


title:
The cycle problem: an intriguing periodicity to the zeros of the Riemann
  zeta function

abstract:
  Summing the values of the real portion of the logarithmic integral of n^rho,
where rho is one of a consecutive series of zeros of the Riemann zeta function,
reveals an unexpected periodicity to the sum. This is the cycle problem.


title:
Phonon-assisted resonant tunneling through a triple-quantum-dot: a
  phonon-signal detector

abstract:
  We study the effect of electron-phonon interaction on current and
zero-frequency shot noise in resonant tunneling through a series
triple-quantum-dot coupling to a local phonon mode by means of a
nonperturbative mapping technique along with the Green function formulation. By
fixing the energy difference between the first two quantum dots to be equal to
phonon frequency and sweeping the level of the third quantum dot, we find a
largely enhanced current spectrum due to phonon effect, and in particular we
predict current peaks corresponding to phonon-absorption and -emission assisted
resonant tunneling processes, which shows that this system can be acted as a
sensitive phonon-signal detector or as a cascade phonon generator.


title: Doping dependence of the vortex-core energy in bilayer films of cuprates

abstract:
  The energy needed to create a vortex core is the basic ingredient to address
the physics of thermal vortex fluctuations in underdoped cuprates. Here we
theoretically investigate its role on the occurrence of the
Beresinskii-Kosterlitz-Thouless transition in a bilayer film with
inhomogeneity. From the comparison with recent measurements of the penetration
depth in two-unit cell thin films of
Y$_{1-x}$Ca$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\d}$ (YBCO) by Hetel et al. [Nat. Phys.
3, 700 (2007)] we can extract the value of the vortex-core energy $\mu$, and
show that $\mu$ scales linearly with $T_c$ at low doping.


title:
GRB neutrinos, Lorenz Invariance Violation and the influence of
  background cosmology

abstract:
  Modern ideas in quantum gravity predict the possibility of Lorenz Invariance
Violation (LIV) manifested e.g. by energy dependent modification of standard
relativistic dispersion relation. In a recent paper Jacob and Piran proposed
that time of flight delays in high energy neutrinos emitted by gamma ray bursts
(GRBs) located at cosmological distances can become a valuable tool for setting
limits on LIV theories. However, current advances in observational cosmology
suggest that our Universe is dominated by dark energy with relatively little
guidance on its nature thus leading to several cosmological scenarios
compatible with observations.
  In this paper we raise the issue of how important, in the context of testing
LIV theories, is our knowledge of background cosmological model. Specifically
we calculate expected time lags for high-energy (100 TeV) neutrinos in
different cosmological models. Out of many particular models of dark energy we
focus on five: $\Lambda$CDM, quintessence, quintessence with time varying
equation of state, brane-world and generalized Chaplygin gas model as
representative for various competing approaches. The result is that uncertainty
introduced by our ignorance concerning the right phenomenological model
describing dark energy dominated universe is considerable and may obscure
bounds derived from studying time delays from cosmological sources.


title:
Automatic Pattern Classification by Unsupervised Learning Using
  Dimensionality Reduction of Data with Mirroring Neural Networks

abstract:
  This paper proposes an unsupervised learning technique by using Multi-layer
Mirroring Neural Network and Forgy's clustering algorithm. Multi-layer
Mirroring Neural Network is a neural network that can be trained with
generalized data inputs (different categories of image patterns) to perform
non-linear dimensionality reduction and the resultant low-dimensional code is
used for unsupervised pattern classification using Forgy's algorithm. By
adapting the non-linear activation function (modified sigmoidal function) and
initializing the weights and bias terms to small random values, mirroring of
the input pattern is initiated. In training, the weights and bias terms are
changed in such a way that the input presented is reproduced at the output by
back propagating the error. The mirroring neural network is capable of reducing
the input vector to a great degree (approximately 1/30th the original size) and
also able to reconstruct the input pattern at the output layer from this
reduced code units. The feature set (output of central hidden layer) extracted
from this network is fed to Forgy's algorithm, which classify input data
patterns into distinguishable classes. In the implementation of Forgy's
algorithm, initial seed points are selected in such a way that they are distant
enough to be perfectly grouped into different categories. Thus a new method of
unsupervised learning is formulated and demonstrated in this paper. This method
gave impressive results when applied to classification of different image
patterns.


title:
Spatial aggregation of local likelihood estimates with applications to
  classification

abstract:
  This paper presents a new method for spatially adaptive local (constant)
likelihood estimation which applies to a broad class of nonparametric models,
including the Gaussian, Poisson and binary response models. The main idea of
the method is, given a sequence of local likelihood estimates (``weak''
estimates), to construct a new aggregated estimate whose pointwise risk is of
order of the smallest risk among all ``weak'' estimates. We also propose a new
approach toward selecting the parameters of the procedure by providing the
prescribed behavior of the resulting estimate in the simple parametric
situation. We establish a number of important theoretical results concerning
the optimality of the aggregated estimate. In particular, our ``oracle'' result
claims that its risk is, up to some logarithmic multiplier, equal to the
smallest risk for the given family of estimates. The performance of the
procedure is illustrated by application to the classification problem. A
numerical study demonstrates its reasonable performance in simulated and
real-life examples.


title: Inducing periodicity and chaos by negative feedback

abstract:
  This paper has been withdrawn due to an error in the proof of the main
theorem.


title:
Gravitational lensing time delays as a tool for testing Lorentz
  Invariance Violation

abstract:
  Despite the fact that quantum gravity theory still remains elusive, it is
generally expected that it will bring the picture of a space-time foam at short
distances leading to Lorenz Invariance Violation (LIV) manifested e.g. by
energy dependent modification of standard relativistic dispersion relation. One
direction of research, pursued intensively is to measure energy dependent time
of arrival delays in photons emitted by astrophysical sources located at
cosmological distances. This is tempered however by our ignorance of either
intrinsic delay (at source frame) in different energy channels or as recently
shown, the correct model of the background cosmology.
  In this paper we propose a new test based on gravitational lensing.
Monitoring time delays between images performed in different energy channels
(e.g. optical - low energy and TeV photons) may reveal extra delays due to
distorted dispersion relation typical in LIV theories - a test which is free
from the systematics inherent in other settings.


title:
Numerical analysis of three-band models for CuO planes as candidates for
  a spontaneous T violating orbital current phase

abstract:
  Recently, we have numerically evaluated the current-current correlation
function for the ground states of three-band models for the CuO planes of
high-Tc superconductors at hole doping x=1/8 using systems with 24 sites and
periodic boundary conditions. In this article, the numerical analysis is
explicated in detail and extended to a wider range of parameters. Our results
show no evidence for the time-reversal symmetry violating current patterns
recently proposed by Varma. If such current patterns exist, our results
indicate that the energy associated with the loop currents must be smaller than
5 meV per link even if the on-site chemical potential on the oxygen sites,
which is generally assumed to be of the order of 3.6 eV, is taken to zero, as
advocated by Varma. We also vary the inter-atomic Coulomb repulsion scale and
find only a weak dependence on this parameter. So while our studies do not rule
out the existence of such current patterns, they do rule out that quantum
critical fluctuations of these patterns are responsible for phenomena occurring
at significantly higher energies such as the superconductivity or the anomalous
properties observed in the strange metal phase provided the CuO superconductors
are adequately described by any of the three-band models discussed.


title: Mass Determination of New States at Hadron Colliders

abstract:
  We propose an improved method for hadron-collider mass determination of new
states that decay to a massive, long-lived state like the LSP in the MSSM. We
focus on pair produced new states which undergo three-body decay to a pair of
visible particles and the new invisible long-lived state. Our approach is to
construct a kinematic quantity which enforces all known physical constraints on
the system. The distribution of this quantity calculated for the observed
events has an endpoint that determines the mass of the new states. However we
find it much more efficient to determine the masses by fitting to the entire
distribution and not just the end point. We consider the application of the
method at the LHC for various models and demonstrate that the method can
determine the masses within about 6 GeV using only 250 events. This implies the
method is viable even for relatively rare processes at the LHC such as
neutralino pair production.


title: Schur-Weyl duality for orthogonal groups

abstract:
  We prove Schur--Weyl duality between the Brauer algebra $\mathfrak{B}_n(m)$
and the orthogonal group $O_{m}(K)$ over an arbitrary infinite field $K$ of odd
characteristic. If $m$ is even, we show that each connected component of the
orthogonal monoid is a normal variety; this implies that the orthogonal Schur
algebra associated to the identity component is a generalized Schur algebra. As
an application of the main result, an explicit and characteristic-free
description of the annihilator of $n$-tensor space $V^{\otimes n}$ in the
Brauer algebra $mathfrak{B}_n(m)$ is also given.


title: Recent results on D^0 mixing from Belle

abstract:
  We report on recent measurements of the $D^0-\bar{D}^0$ mixing and $CP$
violation parameters performed by the Belle experiment. The evidence for the
mixing phenomena in the system of neutral $D$ mesons, arising in the study of
$D^0\to K^+K^-, \pi^+\pi^-$ decays is presented first. Using a time dependent
Dalitz analysis of $D^0\to K_S\pi^+\pi^-$ decays we also obtained the most
precise up-to-date determination of the mass difference of the two $D$ meson
mass eigenstates. The presented results are based on 540 fb$^{-1}$ of data
recorded by the Belle detector at the KEKB $e^+e^-$ collider. We conclude with
short prospects for the future measurements.


title: Hamiltonian Formalism in the Presence of Higher Derivatives

abstract:
  A short review of basic formulas from Hamiltonian formalism in classical
mechanics in the case when Lagrangian contains N time-derivatives of n
coordinate variables. For non-local models N=infinity.


title:
Soft heavy-ion physics from hydrodynamics with statistical hadronization
  - predictions for the Large Hadron Collider

abstract:
  Hydrodynamics merged with single-freeze-out statistical hadronization is used
to describe the midrapidity hadron production in relativistic heavy-ion
collisions at the highest RHIC energies and to make predictions for the LHC.
Thermodynamic properties of the quark-gluon plasma are taken from lattice
simulations, at low temperatures the hadron-gas equation of state is used,
while in the cross-over region an interpolation between the two equations of
state is constructed. The initial condition for hydrodynamics is obtained from
a Glauber profile for the entropy, with the initial central temperature Ti. The
conditions obtained from the hydrodynamic expansion at the freeze-out
temperature Tf are used as input for the thermal event generator THERMINATOR.
Basic physical observables are obtained: the transverse-momentum spectra, the
elliptic flow coefficient v2, and the HBT radii. The femtoscopic observables
are evaluated with the help of the two-particle method which accounts for the
resonance decays and Coulomb final-state interactions. The problem of a
simultaneous description of all discussed observables is addressed, with the
conclusion that at the highest RHIC energies our approach gives a quite
satisfactory global description of soft hadronic observables. Some
discrepancies may be attributed to the absence of the final-state elastic
interactions among hadrons. Extrapolating Ti to higher values allows for global
predictions for soft hadronic physics at the LHC. We test Ti=400, 450, and 500
MeV, and observe the expected growth of particle multiplicities and the
increase of the flow, resulting in smaller slopes of the pT-spectra. The
elliptic flow of pions exhibits saturation, with v2 remaining practically
constant, while the HBT radii increase moderately with Ti.


title:
A Common View on Strong, Uniform, and Other Notions of Equivalence in
  Answer-Set Programming

abstract:
  Logic programming under the answer-set semantics nowadays deals with numerous
different notions of program equivalence. This is due to the fact that
equivalence for substitution (known as strong equivalence) and ordinary
equivalence are different concepts. The former holds, given programs P and Q,
iff P can be faithfully replaced by Q within any context R, while the latter
holds iff P and Q provide the same output, that is, they have the same answer
sets. Notions in between strong and ordinary equivalence have been introduced
as theoretical tools to compare incomplete programs and are defined by either
restricting the syntactic structure of the considered context programs R or by
bounding the set A of atoms allowed to occur in R (relativized equivalence).For
the latter approach, different A yield properly different equivalence notions,
in general. For the former approach, however, it turned out that any
``reasonable'' syntactic restriction to R coincides with either ordinary,
strong, or uniform equivalence. In this paper, we propose a parameterization
for equivalence notions which takes care of both such kinds of restrictions
simultaneously by bounding, on the one hand, the atoms which are allowed to
occur in the rule heads of the context and, on the other hand, the atoms which
are allowed to occur in the rule bodies of the context. We introduce a general
semantical characterization which includes known ones as SE-models (for strong
equivalence) or UE-models (for uniform equivalence) as special cases.
Moreover,we provide complexity bounds for the problem in question and sketch a
possible implementation method.
  To appear in Theory and Practice of Logic Programming (TPLP).


title: Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires

abstract:
  The thermal conductivity of silicon nanowires (SiNWs) is investigated by
molecular dynamics (MD) simulation. It is found that the thermal conductivity
of SiNWs can be reduced exponentially by isotopic defects at room temperature.
The thermal conductivity reaches the minimum, which is about 27% of that of
pure 28Si NW, when doped with fifty percent isotope atoms. The thermal
conductivity of isotopic-superlattice structured SiNWs depends clearly on the
period of superlattice. At a critical period of 1.09 nm, the thermal
conductivity is only 25% of the value of pure Si NW. An anomalous enhancement
of thermal conductivity is observed when the superlattice period is smaller
than this critical length. The ultra-low thermal conductivity of superlattice
structured SiNWs is explained with phonon spectrum theory.


title:
On string solutions of Bethe equations in N=4 supersymmetric Yang-Mills
  theory

abstract:
  The Bethe equations, arising in description of the spectrum of the dilatation
operator for the su(2) sector of the N=4 supersymmetric Yang-Mills theory, are
considered in the anti-ferromagnetic regime. These equations are deformation of
those for the Heisenberg XXX magnet. It is proven that in the thermodynamic
limit roots of the deformed equations group into strings. It is proven that the
corresponding Yang's action is convex, which implies uniqueness of solution for
centers of the strings. The state formed of strings of length (2n+1) is
considered and the density of their distribution is found. It is shown that the
energy of such a state decreases as n grows. It is observed that
non-analyticity of the left hand side of the Bethe equations leads to an
additional contribution to the density and energy of strings of even length.
Whence it is concluded that the structure of the anti-ferromagnetic vacuum is
determined by the behaviour of exponential corrections to string solutions in
the thermodynamic limit and possibly involves strings of length 2.


title: Tunneling of interacting fermions in 1D systems

abstract:
  Using the self-consistent Hartree-Fock approximation for spinless electrons
at zero temperature, we study tunneling of the interacting electron gas through
a single delta-barrier in a finite one-dimensional (1D) wire connected to
contacts. Our results exhibit features known from correlated many-body models.
In particular, the conductance decays with the wire length as $\propto
L^{-2\alpha}$, where the power $\alpha$ is universal. We also show that a
similar result for a wire conductance can be extracted from the persistent
current (I) through the delta-barrier in a 1D ring, where it is known that I
\propto L^{-1-\alpha}$.


title: Coherent transport of interacting electrons through a single scatterer

abstract:
  Using the self-consistent Hartree-Fock method, we calculate the persistent
current of weakly-interacting spinless electrons in a one-dimensional ring
containing a single delta-barrier. We find that the persistent current decays
with the system length (L) asymptotically like $I \propto L^{-1-\alpha}$, where
$\alpha > 0$ is the power depending only on the electron-electron interaction.
We also simulate tunneling of the weakly-interacting one-dimensional electron
gas through a single delta-barrier in a finite wire biased by contacts. We find
that the Landauer conductance decays with the system length asymptotically like
$L^{-2\alpha}$. The power laws $L^{-1-\alpha}$ and $L^{-2\alpha}$ have so far
been observed only in correlated models. Their existence in the Hartree-Fock
model is thus surprising.


title: Cardinalities of k-distance sets in Minkowski spaces

abstract:
  A subset of a metric space is a k-distance set if there are exactly k
non-zero distances occuring between points. We conjecture that a k-distance set
in a d-dimensional Banach space (or Minkowski space), contains at most (k+1)^d
points, with equality iff the unit ball is a parallelotope. We solve this
conjecture in the affirmative for all 2-dimensional spaces and for spaces where
the unit ball is a parallelotope. For general spaces we find various weaker
upper bounds for k-distance sets.


title: The Numerical Simulation of Turbulence

abstract:
  In this contribution, I give an overview of the various approaches toward the
numerical modelling of turbulence, particularly, in the interstellar medium.
The discussion is placed in a physical context, i. e. computational problems
are motivated from basic physical considerations. Presenting selected examples
for solutions to these problems, I introduce the basic ideas of the most
commonly used numerical methods.


title:
Tunneling of interacting one-dimensional electrons through a single
  scatterer: Luttinger liquid behavior in the Hartree-Fock model

abstract:
  We study tunneling of weakly-interacting spinless electrons at zero
temperature through a single delta-barrier in one-dimensional wires and rings
of finite lengths. Our numerical calculations are based on the self-consistent
Hartree-Fock approximation, nevertheless, our results exhibit features known
from correlated many-body models. In particular, the transmission in a wire of
length L at the Fermi level is proportional to $L^{-2\alpha}$ with the
universal power $\alpha$ (depending on the electron-electron interaction only,
not on the strength of the delta-barrier). Similarly, the persistent current in
a ring of the circumference $L$ obeys the rule $I\propto L^{-1-\alpha}$ known
from the Luttinger liquid and Hubbard models. We show that the transmission at
the Fermi level in the wire is related to the persistent current in the ring at
the magnetic flux h/4e.


title: Affine Algebraic Varieties

abstract:
  In this paper, we give new criteria for affineness of a variety defined over
$\Bbb{C}$. Our main result is that an irreducible algebraic variety $Y$ (may be
singular) of dimension $d$ ($d\geq 1$) defined over $\Bbb{C}$ is an affine
variety if and only if $Y$ contains no complete curves, $H^i(Y,
{\mathcal{O}}_Y)=0$ for all $i>0$ and the boundary $X-Y$ is support of a big
divisor, where $X$ is a projective variety containing $Y$. We construct three
examples to show that a variety is not affine if it only satisfies two
conditions among these three conditions. We also give examples to demonstrate
the difference between the behavior of the boundary divisor $D$ and the
affineness of $Y$. If $Y$ is an affine variety, then the ring $\Gamma (Y,
{\mathcal{O}}_Y)$ is noetherian. However, to prove that $Y$ is an affine
variety, we do not start from this ring. We explain why we do not need to check
the noetherian property of the ring $\Gamma (Y, {\mathcal{O}}_Y)$ directly but
use the techniques of sheaf and cohomology.


title: On stable determination of potential by boundary measurements

abstract:
  We give new stability estimates for the Gel'fand-Calderon inverse boundary
value problem


title: What is the difference between a square and a triangle?

abstract:
  We offer a reader-friendly introduction to the attracting edge problem (also
known as the "triangle conjecture") and its most general current solution of
Limic and Tarr\`es (2007). Little original research is reported; rather this
article ``zooms in'' to describe the essential characteristics of two different
techniques/approaches verifying the almost sure existence of the attracting
edge for the strongly edge reinforced random walk (SERRW) on a square. Both
arguments extend straightforwardly to the SERRW on even cycles. Finally, we
show that the case where the underlying graph is a triangle cannot be studied
by a simple modification of either of the two techniques.


title: Curved Herbig-Haro Jets: Simulations and Experiments

abstract:
  Herbig-Haro jets often show some degree of curvature along their path, in
many cases produced by the ram pressure of a side-wind. We present simulations
of both laboratory and astrophysical curved jets and experimental results from
laboratory experiments. We discuss the properties and similarities of the
laboratory and astrophysical flow, which show the formation of internal shocks
and working surfaces. In particular the results illustrate how the break-up of
the bow-shock and clumps in the flow are produced without invoking jet
variability; we also discuss how jet rotation reduces the growth of the
Rayleigh-Taylor instability in curved jets.


title:
Persistent current of correlated electrons in mesoscopic ring with
  impurity

abstract:
  The persistent current of correlated electrons in a continuous
one-dimensional ring with a single scatterer is calculated by solving the
many-body Schrodinger equation for several tens of electrons interacting via
the electron-electron (e-e) interaction of finite range. The problem is solved
by the configuration-interaction (CI) and diffusion Monte Carlo (DMC) methods.
The CI and DMC results are in good agreement. In both cases, the persistent
current $I$ as a function of the ring length $L$ exhibits the asymptotic
dependence $I \propto L^{-1-\alpha}$ typical of the Luttinger liquid, where the
power $\alpha$ depends only on the e-e interaction. The numerical values of
$\alpha$ agree with the known formula of the renormalisation-group theory.


title:
On the evolution of multiple low mass planets embedded in a circumbinary
  disc

abstract:
  Previous work has shown that the tidal interaction between a binary system
and a circumbinary disc leads to the formation of a large inner cavity in the
disc. Subsequent formation and inward migration of a low mass planet causes it
to become trapped at the cavity edge, where it orbits until further mass growth
or disc dispersal. The question of how systems of multiple planets in
circumbinary discs evolve has not yet been addressed. Here, we present a suite
of simulations which study the evolution of pairs of planets migrating in the
disc. We also present the results of hydrodynamic simulations of five-planet
systems, and study their long term evolution after disc dispersal using a
N-body code. For the two-planet simulations we assume that the innermost planet
has migrated to the edge of the inner cavity and remains trapped there, and
study the subsequent evolution of the system as the outermost planet migrates
inward. We find that the outcomes largely depend on the mass ratio q=m_i/m_o,
where m_i (m_o) is the mass of the innermost (outermost) planet. For q<1,
planets usually undergo dynamical scattering or orbital exchange. For values of
q>1 the systems reach equilibrium configurations in which the planets are
locked into mean motion resonances, and remain trapped at the edge of the inner
cavity without further migration. Most simulations of five-planet systems we
performed resulted in collisions and scattering events, such that only a single
planet remained in orbit about the binary. In one case however, a multiplanet
resonant system was found to be dynamically stable over long time scales,
suggesting that such systems may be observed in planet searches focussed on
close binary systems.


title:
Possible persistent current in a ring made of the perfect crystalline
  insulator

abstract:
  A mesoscopic conducting ring pierced by magnetic flux is known to support the
persistent electron current. Here we propose possibility of the persistent
current in the ring made of the perfect crystalline insulator. We consider a
ring-shaped lattice of one-dimensional "atoms" with a single energy level. We
express the Bloch states in the lattice as a linear combination of atomic
orbitals. The discrete energy level splits into the energy band which serves as
a simple model of the valence band. We show that the insulating ring (with the
valence band fully filled by electrons) supports a nonzero persistent current,
because each atomic orbital overlaps with its own tail when making one loop
around the ring. In the tight-binding limit only the neighboring orbitals
overlap. In that limit the persistent current at full filling becomes zero
which is a standard result.


title:
A p-adic approach to local analytic dynamics: analytic flows and
  analytic maps tangent to the identity

abstract:
  In this note, we will consider the question of local equivalence of analytic
functions which fix the origin and are tangent to the identity, as well as the
question of flows of analytic vector fields. All mappings and equivalences are
considered in the non-archimedean context e.g. all norms can be considered
$p$-adic norms. We show that any two mappings $f$ and $g$ which are formally
equivalent are also analytically equivalent, and we show that analytic vector
fields generate analytic flows. We consider the related questions of roots and
centralizers for analytic mappings. In this setting, anything which can be done
formally can also be done analytically.


title: High resolution quantization and entropy coding of jump processes

abstract:
  We study the quantization problem for certain types of jump processes. The
probabilities for the number of jumps are assumed to be bounded by Poisson
weights. Otherwise, jump positions and increments can be rather generally
distributed and correlated. We show in particular that in many cases entropy
coding error and quantization error have distinct rates. Finally, we
investigate the quantization problem for the special case of
$\mathbb{R}^d$-valued compound Poisson processes.


title:
Estimating the total infrared luminosity of galaxies up to z~2 from mid-
  and far-infrared observations

abstract:
  We present the observed correlations between rest-frame 8, 24, 70 and 160 um
monochromatic luminosities and measured total infrared luminosities L_IR of
galaxies detected by Spitzer. Our sample consists of 372 star-forming galaxies
with individual detections and flux measurements at 8, 24, 70 and 160 um. We
have spectroscopic redshifts for 93% of these sources, and accurate photometric
redshifts for the remainder. We also used a stacking analysis to measure the IR
fluxes of fainter sources at higher redshifts. We show that the monochromatic
mid and far-infrared luminosities are strongly correlated with the total
infrared luminosity and our stacking analysis confirms that these correlations
also hold at higher redshifts. We provide relations between monochromatic
luminosities and total infrared luminosities L_IR that should be reliable up to
z~2 (z~1.1) for ULIRGs (LIRGs). In particular, we can predict L_IR with
accuracies of 37% and 54% from the 8 and 24 um fluxes, while the best tracer is
the 70 um flux. Combining bands leads to slightly more accurate estimates. For
example, combining the 8 and 24 um luminosities predicts L_IR with an accuracy
of 34%. Our results are generally compatible with previous studies, and the
small changes are probably due to differences in the sample selection criteria.
We can rule out strong evolution in dust properties with redshift up to z~1.
Finally, we show that infrared and sub-millimeter observations are
complementary means of building complete samples of star-forming galaxies, with
the former being more sensitive for z<~2 and the latter at higher z>~2.


title:
On the Dirichlet problem for prescribed mean curvature equation over
  general domains

abstract:
  We study and solve the Dirichlet problem for graphs of prescribed mean
curvature in $\mathbb R^{n+1}$ over general domains $\Omega$ without requiring
a mean convexity assumption. By using pieces of nodoids as barriers we first
give sufficient conditions for the solvability in case of zero boundary values.
Applying a result by Schulz and Williams we can then also solve the Dirichlet
problem for boundary values satisfying a Lipschitz condition.


title: Universality of the de Broglie-Einstein velocity equation

abstract:
  The de Broglie-Einstein velocity equation is derived for a relativistic
particle by using the energy and momentum relations in terms of wave and matter
properties. It is shown that the velocity equation is independent from the
relativistic effects and is valid also for the non-relativistic case. The
results of this property is discussed.


title: Projective structures, grafting, and measured laminations

abstract:
  We show that grafting any fixed hyperbolic surface defines a homeomorphism
from the space of measured laminations to Teichmuller space, complementing a
result of Scannell-Wolf on grafting by a fixed lamination. This result is used
to study the relationship between the complex-analytic and geometric coordinate
systems for the space of complex projective ($\CP^1$) structures on a surface.
  We also study the rays in Teichmuller space associated to the grafting
coordinates, obtaining estimates for extremal and hyperbolic length functions
and their derivatives along these grafting rays.


title:
Resonance enhanced isotope-selective photoionization of YbI for ion trap
  loading

abstract:
  Neutral Ytterbium (YbI) and singly ionized Ytterbium (YbII) is widely used in
experiments in quantum optics, metrology and quantum information science. We
report on the investigation of isotope selective two-photoionisation of YbI
that allows for efficient loading of ion traps with YbII. Results are presented
on two-colour (399 nm and 369 nm) and single-colour (399 nm) photoionisation
and their efficiency is compared to electron impact ionisation. Nearly
deterministic loading of a desired number of YbII ions into a linear Paul trap
is demonstrated.


title: Field Camera Unit for WSO-UV: Phase A Study Report

abstract:
  World Space Observatory UltraViolet (WSO-UV) is a multipurpose space
observatory, made by a 170 cm aperture telescope, capable of UV high-resolution
spectroscopy, long slit low-resolution spectroscopy, and deep UV and optical
imaging. With a nominal mission life time of 5 years, and a planned extension
to 10 years, from a geosynchronous orbit with an inclination of 51.8 degrees,
WSO-UV will provide observations of exceptional importance for the study of
many unsolved astrophysical problems. WSO-UV is implemented in the framework of
a collaboration between Russia (chair), China, Germany, Italy, Spain, and
Ukraine. This book illustrates the results of the feasibility study for the
Field Camera Unit (FCU), a multi-spectral radial instrument on the focal plane
of WSO-UV. The book provides an overview of the key science topics that are
drivers to the participation of the Italian astronomical community in the
WSO-UV project. The science drivers here illustrated have been used to define
the technical requirements for the conceptual and architectural design of the
Field Camera Unit (FCU) focal plane instrument. In Chapter I we show that
WSO-UV will give a significant contribution to solve the key astronomical
problems individuated by the ASTRONET consortium, and which are driving the
European Space Agency Cosmic Vision program. Chapter II elucidates the
scientific requirements for WSO-UV FCU instrument, discussed in Chapter I,
which are translated in a list of verifiable top level requirements usable to
make the conceptual design of the FCU instrument. Chapter III is dedicated to
the Field Camera Unit opto-mechanical design, its detectors and electronics
subsystems. Finally, Chapter IV outlines the AIV and GSE plans and activities
for the FCU instrument.


title:
Electromagnetic form factor via Minkowski and Euclidean Bethe-Salpeter
  amplitudes

abstract:
  The electromagnetic form factors calculated through Euclidean Bethe-Salpeter
amplitude and through the light-front wave function are compared with the one
found using the Bethe-Salpeter amplitude in Minkowski space. The form factor
expressed through the Euclidean Bethe-Salpeter amplitude (both within and
without static approximation) considerably differs from the Minkowski one,
whereas form factor found in the light-front approach is almost
indistinguishable from it.


title:
Room temperature observation of electron resonant tunneling through
  InAs/AlAs quantum dots

abstract:
  Molecular beam epitaxy is employed to manufacture self-assembled InAs/AlAs
quantum-dot resonant tunneling diodes. Resonant tunneling current is
superimposed on the thermal current, and they make up the total electron
transport in devices. Steps in current-voltage characteristics and peaks in
capacitance-voltage characteristics are explained as electron resonant
tunneling via quantum dots at 77K or 300K, and this is the first time that
resonant tunneling is observed at room temperature in III-V quantum-dot
materials. Hysteresis loops in the curves are attributed to hot electron
injection/emission process of quantum dots, which indicates the concomitant
charging/discharging effect.


title: Nucleosome shape dictates chromatin-fiber structure

abstract:
  Apart from being the gateway for all access to the eukaryotic genome,
chromatin has in recent years been identified as carrying an epigenetic code
regulating transcriptional activity. The detailed knowledge of this code
contrasts the ignorance of the fiber structure which it regulates, and none of
the suggested fiber models are capable of predicting the most basic quantities
of the fiber (diameter, nucleosome line density, etc.). We address this
three-decade-old problem by constructing a simple geometrical model based on
the nucleosome shape alone. Without fit parameters we predict the observed
properties of the condensed chromatin fiber (e.g. its 30 nm diameter), the
structure, and how the fiber changes with varying nucleosome repeat length. Our
approach further puts the plethora of previously suggested models within a
coherent framework, and opens the door to detailed studies of the interplay
between chromatin structure and function.


title: Editorial: Statistics and forensic science

abstract:
  Forensic science is usually taken to mean the application of a broad spectrum
of scientific tools to answer questions of interest to the legal system.
Despite such popular television series as CSI: Crime Scene Investigation and
its spinoffs--CSI: Miami and CSI: New York--on which the forensic scientists
use the latest high-tech scientific tools to identify the perpetrator of a
crime and always in under an hour, forensic science is under assault, in the
public media, popular magazines [Talbot (2007), Toobin (2007)] and in the
scientific literature [Kennedy (2003), Saks and Koehler (2005)]. Ironically,
this growing controversy over forensic science has occurred precisely at the
time that DNA evidence has become the ``gold standard'' in the courts, leading
to the overturning of hundreds of convictions many of which were based on
clearly less credible forensic evidence, including eyewitness testimony [Berger
(2006)].


title: Random quantum codes from Gaussian ensembles and an uncertainty relation

abstract:
  Using random Gaussian vectors and an information-uncertainty relation, we
give a proof that the coherent information is an achievable rate for
entanglement transmission through a noisy quantum channel. The codes are random
subspaces selected according to the Haar measure, but distorted as a function
of the sender's input density operator. Using large deviations techniques, we
show that classical data transmitted in either of two Fourier-conjugate bases
for the coding subspace can be decoded with low probability of error. A
recently discovered information-uncertainty relation then implies that the
quantum mutual information for entanglement encoded into the subspace and
transmitted through the channel will be high. The monogamy of quantum
correlations finally implies that the environment of the channel cannot be
significantly coupled to the entanglement, and concluding, which ensures the
existence of a decoding by the receiver.


title:
Thermodynamics and Kinetics of a Go Proteinlike Heteropolymer Model with
  Two-State Folding Characteristics

abstract:
  We present results of Monte Carlo computer simulations of a coarse-grained
hydrophobic-polar Go-like heteropolymer model and discuss thermodynamic
properties and kinetics of an exemplified heteropolymer, exhibiting two-state
folding behavior. It turns out that general, characteristic folding features of
realistic proteins with a single free-energy barrier can also be observed in
this simplified model, where the folding transition is primarily driven by the
hydrophobic force.


title:
The Plebanski action extended to a unification of gravity and Yang-Mills
  theory

abstract:
  We study a unification of gravity with Yang-Mills fields based on a simple
extension of the Plebanski action to a Lie group G which contains the local
lorentz group. The Coleman-Mandula theorem is avoided because the theory has no
global spacetime symmetry. This may be applied to Lisi's proposal of an E8
unified theory, giving a fully E8 invariant action. The extended form of the
Plebanski action suggests a new class of spin foam models.


title: How paper folds: bending with local constraints

abstract:
  A variational framework is introduced to describe how a surface bends when it
is subject to local constraints on its geometry. This framework is applied to
describe the patterns of a folded sheet of paper. The unstretchability of paper
implies a constraint on the surface metric; bending is penalized by an energy
quadratic in mean curvature. The local Lagrange multipliers enforcing the
constraint are identified with a conserved tangential stress that couples to
the extrinsic curvature of the sheet. The framework is illustrated by examining
the deformation of a flat sheet into a generalized cone.


title:
Equivalence of conditional and external field ensembles in absorbing
  state phase transitions

abstract:
  I comment on the relation between two sampling methods for absorbing state
models. It is shown that a certain ensemble without external field conditional
to activity coincides with the unconditional ensemble for sufficiently small
external field. The actual physical processes involved are identical and the
derivation of the identity of the scaling behaviour relies on a single
(established) scaling law. While the conditional ensemble by construction does
not contain information about the system with large external field, it contains
all information about the limit of vanishing external field and about the
vicinity of the critical point: Finite size scaling as well as critical scaling
in the temperature-like variable or in (small) external field.


title:
Electron resonant tunneling through InAs/GaAs quantum dots embedded in a
  Schottky diode with an AlAs insertion layer

abstract:
  Molecular beam epitaxy is employed to manufacture self-assembled InAs/GaAs
quantum dot Schottky resonant tunneling diodes. By virtue of a thin AlAs
insertion barrier, the thermal current is effectively reduced and electron
resonant tunneling through quantum dots under both forward and reverse biased
conditions is observed at relatively high temperature of 77K. The ground states
of quantum dots are found to be at ~0.19eV below the conduction band of GaAs
matrix. The theoretical computations are in conformity with experimental data.


title:
On separation of variables and completeness of the Bethe ansatz for
  quantum gl_N Gaudin model

abstract:
  In this note, we discuss implications of the results obtained in [MTV4]. It
was shown there that eigenvectors of the Bethe algebra of the quantum gl_N
Gaudin model are in a one-to-one correspondence with Fuchsian differential
operators with polynomial kernel. Here, we interpret this fact as a separation
of variables in the gl_N Gaudin model. Having a Fuchsian differential operator
with polynomial kernel, we construct the corresponding eigenvector of the Bethe
algebra. It was shown in [MTV4] that the Bethe algebra has simple spectrum if
the evaluation parameters of the Gaudin model are generic. In that case, our
Bethe ansatz construction produces an eigenbasis of the Bethe algebra.


title:
Thermodynamics of Peptide Aggregation Processes. An Analysis from
  Perspectives of Three Statistical Ensembles

abstract:
  We employ a mesoscopic model for studying aggregation processes of
protein-like hydrophobic-polar heteropolymers. By means of multicanonical Monte
Carlo computer simulations, we find strong indications that peptide aggregation
is a phase separation process, in which the microcanonical entropy exhibits a
convex intruder due to nonnegligible surface effects of the small systems. We
analyze thermodynamic properties of the conformational transitions accompanying
the aggregation process from the multicanonical, canonical, and microcanonical
perspective. It turns out that the microcanonical description is particularly
advantageous as it allows for unraveling details of the phase-separation
transition in the thermodynamic region, where the temperature is not a suitable
external control parameter anymore.


title:
SUMER-Hinode observations of microflares: excitation of molecular
  hydrogen

abstract:
  Concentrations of molecular hydrogen (H2) have been detected by SUMER in
active region plage. The H2 is excited by O VI line emission at 1031.94 A
which, although not observed, must be brightening along with the observed
transition region line, Si III 1113.24 A. We have made co-ordinated
observations of active region plage with the spectrometer SUMER/SoHO in lines
of H2 1119.10 A and Si III 1113.24 A and with XRT/Hinode X-ray and SOT/Hinode
Ca II filters. In six hours of observation, six of the seven H2 events seen
occurred near a footpoint of a brightening X-ray loop. The seventh is
associated with an unusually strong Si III plasma outflow. We conclude that
microflare energy dissipation heats the chromosphere, reducing its opacity, so
that O VI microflare emission is able to reach the lower layers of the
chromosphere and excite the H2.


title: Antimatter and Gamma-rays from Dark Matter Annihilation

abstract:
  A brief review of the indirect detection signatures of dark matter is given.
In particular, detection methods of dark matter particle annihilation to
antimatter and gamma-rays are reviewed. With the GLAST satellite soon to be
launched, a crucial window in the energy range of a few GeV up to 300 GeV will
open. The good angular and energy resolution of the instrument means that
structures predicted by cold dark matter models can be searched for. Large,
currently planned ground-based imaging Cherenkov telescope arrays, may further
improve the limits, or discover a signal, if the current understanding of halo
dark matter structure is correct.


title: 5-move equivalence classes of links and their algebraic invariants

abstract:
  We start a systematic analysis of links up to 5-move equivalence. Our
motivation is to develop tools which later can be used to study skein modules
based on the skein relation being deformation of a 5-move (in an analogous way
as the Kauffman skein module is a deformation of a 2-move, i.e. a crossing
change). Our main tools are Jones and Kauffman polynomials and the fundamental
group of the 2-fold branch cover of S^3 along a link. We use also the fact that
a 5-move is a composition of two rational \pm (2,2)-moves (i.e. \pm 5/2-moves)
and rational moves can be analyzed using the group of Fox colorings and its
non-abelian version, the Burnside group of a link. One curious observation is
that links related by one (2,2)-move are not 5-move equivalent. In particular,
we partially classify (up to 5-moves)
  3-braids, pretzel and Montesinos links, and links up to 9 crossings.


title: Matter-wave solitons with a periodic, piecewise-constant nonlinearity

abstract:
  Motivated by recent proposals of ``collisionally inhomogeneous''
Bose-Einstein condensates (BECs), which have a spatially modulated scattering
length, we study the existence and stability properties of bright and dark
matter-wave solitons of a BEC characterized by a periodic, piecewise-constant
scattering length. We use a ``stitching'' approach to analytically approximate
the pertinent solutions of the underlying nonlinear Schr\"odinger equation by
matching the wavefunction and its derivatives at the interfaces of the
nonlinearity coefficient. To accurately quantify the stability of bright and
dark solitons, we adapt general tools from the theory of perturbed Hamiltonian
systems. We show that solitons can only exist at the centers of the constant
regions of the piecewise-constant nonlinearity. We find both stable and
unstable configurations for bright solitons and show that all dark solitons are
unstable, with different instability mechanisms that depend on the soliton
location. We corroborate our analytical results with numerical computations.

categories: nlin.PS cond-mat.other math.DS physics.atom-ph


title:
On continuous state branching processes: conditioning and
  self-similarity

abstract:
  In this paper, for $\alpha\in (1, 2}$ we show that the $\alpha$-stable
continuous-state branching process and the associated process conditioned never
to become extinct are positive self-similar Markov processes. Understanding the
interaction of the Lamperti transformation for continuous-state branching
processes and the Lamperti transformation for positive self-similar Markov
processes permits accessto a number of explicit results concerning the paths of
stable-continuous branching processes and its conditioned version.


title:
The IPHAS Catalogue of Halpha Emission Line Sources in the Northern
  Galactic Plane

abstract:
  We present a catalogue of point-source Halpha emission line objects selected
from the INT/WFC Photometric H$\alpha$ Survey of the Northern Galactic Plane
(IPHAS). The catalogue covers the magnitude range 13 < r' < 19.5 and includes
northern hemisphere sources in the Galactic latitude range -5 < b < 5 degress.
It is derived from ~1500 square degress worth of imaging data, which represents
80 percent of the final IPHAS survey area. The electronic version of the
catalogue will be updated once the full survey data becomes available. In
total, the present catalogue contains 4853 point sources that exhibit strong
photometric evidence for Halpha emission. We have so far analyzed spectra for
~300 of these sources, confirming more than 95 percent of them as genuine
emission-line stars. A wide range of stellar populations are represented in the
catalogue, including early-type emission line stars, active late-type stars,
interacting binaries, young stellar objects and compact nebulae.
  The spatial distribution of catalogue objects shows overdensities near sites
of recent or current star formation, as well as possible evidence for the warp
of the Galactic plane. Photometrically, the incidence of Halpha emission is
bimodally distributed in r'-i'. The blue peak is made up mostly of early-type
emission line stars, whereas the red peak may signal an increasing contribution
from other objects, such as young/active low-mass stars. We have cross-matched
our Halpha-excess catalogue against the emission-line star catalogue of
Kohoutek & Wehmeyer, as well as against sources in SIMBAD. We find that fewer
than 10 per cent of our sources can be matched to known objects of any type.
Thus IPHAS is uncovering an order of magnitude more faint (r' > 13) emission
line objects than were previously known in the Milky Way.


title:
A maximal inequality for the tail of the bilinear Hardy-Littlewood
  function

abstract:
  Let $(X,\mathcal{B}, \mu, T)$ be an ergodic dynamical system on a non-atomic
finite measure space. We assume without loss of generality that $\mu(X)=1.$
Consider the maximal function $\dis R^*:(f, g) \in L^p\times L^q \to R^*(f,
g)(x) = \sup_{n\geq 1} \frac{f(T^nx)g(T^{2n}x)}{n}.$ We obtain the following
maximal inequality. For each $1<p\leq \infty$ there exists a finite constant
$C_p$ such that for each $\lambda >0,$ and nonnegative functions $f\in L^p$ and
$g\in L^1$
  \mu\{x: R^*(f,g)(x)>\lambda\} \leq
  C_p \bigg(\frac{\|f\|_p\|g\|_1}{\lambda}\bigg)^{1/2}.
  We also show that for each $\alpha>2$ the maximal function $R^*(f,g)$ is a.e.
finite for pairs of functions $(f,g)\in (L(\log L)^{2\alpha}, L^1)$.


title: Off-Diagonal-Long-Range-Order Versus Entanglement

abstract:
  In this short note we discuss the relation between the so-called
Off-Diagonal-Long-Range-Order in many-body interacting quantum systems
introduced by C. N. Yang in Rev. Mod. Phys. {\bf 34}, 694 (1962) and
entanglement. We argue that there is a direct relation between these two
concepts.


title: Spin-droplets in confined quantum Hall systems

abstract:
  Two-dimensional semiconductor quantum dots are studied in the the
filling-factor range 2<v<3. We find both theoretical and experimental evidence
of a collective many-body phenomenon, where a fraction of the trapped electrons
form an incompressible spin-droplet on the highest occupied Landau level. The
phenomenon occurs only when the number of electrons in the quantum dot is
larger than ~30. We find the onset of the spin-droplet regime at v=5/2. This
proposes a finite-geometry alternative to the Moore-Read-type Pfaffian state of
the bulk two-dimensional electron gas. Hence, the spin-droplet formation may be
related to the observed fragility of the v=5/2 quantum Hall state in narrow
quantum point contacts.


title:
Indications for sharp continuous phase transitions at finite
  temperatures connected with the apparent metal-insulator transition in
  two-dimensional disordered systems

abstract:
  In a recent experiment, Lai et al. [Phys. Rev. B 75, 033314 (2007)] studied
the apparent metal-insulator transition (MIT) of a Si quantum well structure
tuning the charge carrier concentration $n$. They observed linear temperature
dependences of the conductivity $\sigma(T,n)$ around the Fermi temperature and
found that the corresponding $T \to 0$ extrapolation $\sigma_0(n)$ exhibits a
sharp bend just at the MIT. Here, reconsidering the data published by Lai et
al., it is shown that this sharp bend is related to a peculiarity of
$\sigma(T=const.,n)$ clearly detectable in the whole $T$ range up to 4 K, the
highest measuring temperature in that work. Since this peculiarity seems not to
be smoothed out with increasing $T$ it may indicate a sharp continuous phase
transition between the regions of apparent metallic and activated conduction to
be present at finite temperature. Hints from the literature of such a behavior
are discussed. Finally, a scaling analysis illuminates similarities to previous
experiments and provides understanding of the shape of the peculiarity and of
sharp peaks found in $d log_{10} \sigma / d n (n)$.


title:
The Poincar\'e recurrence time for the de Sitter space with dynamical
  chaos

abstract:
  For an ordinary thermodynamical system the Poincar\'{e} recurrence time is
exponentially large in the Boltzmann entropy of the system. It turns out, that
for a system with dynamical chaos it is determined by the Kolmogorov-Sinai
entropy and can be considerably shorter. It is shown in this note that for the
de Sitter space with strong mixing properties the mean recurrence time is equal
to the inverse Hubble constant. This means that our universe can have a finite
lifetime bounded by the current age of the universe. After this time, the
universe should recycle itself and this process has neither a beginning nor an
end.


title:
First Detection of 12CO (1--0) Emission from Two Narrow-Line Seyfert 1
  Galaxies

abstract:
  In order to investigate how the growth of galactic bulges progresses with the
growth of central black holes (BHs), we observed molecular gas (fuel for the
coming star formation) in possibly young active galaxies, narrow-line Seyfert 1
galaxies (NLS1s). We present the results of radio observations of 12CO(1--0)
using the Nobeyama Millimeter Array (with 2--4 kpc spatial resolution) for two
FIR-bright NLS1s, yielding the first detection of their CO emission.
Corresponding molecular--gas masses M(H2) of (1-3) X 109 Msun are the 2nd and
4th largest ones among NLS1s. By estimating dynamical masses and bulge masses
M(bulge) for these two NLS1s using CO channel map and CO line widths, we found
M(H2) amount to 0.13--0.35 of these masses. Taking account the star formation
efficiency (~ 0.1), the increase in M(bulge) in those NLS1s in the near future
(~< 10^{7.5} yr) is expected not to be a huge fraction (1--5% of the
preexisting stars). Bulge growth may have finished before BH growth, or
bulge--BH coevolution may proceed with many, occasional discrete events, where
one coevolution event produces only a small amount of mass growth of BHs and of
bulges. We also discuss the ratios of star-formation rate--to--gas accretion
rate onto BHs, finding that two NLS1s have very small ratios (~ 1) compared
with the M(bulge)/M(BH) ratios found in active and inactive galaxies (~ 700).
This huge difference suggests either the non-overlapped coevolution, long star
formation duration or temporarily high accretion rate during NLS1 phase.


title:
Reexamining the neutron skin thickness within a density dependent
  hadronic model

abstract:
  We calculate the skin thickness, binding energy, surface energy and density
profiles within the Dirac solution of a density dependent hadronic model and
compare with the NL3 parametrization results of the non-linear Wallecka model.
The asymmetry for polarized electron scattering is also obtained using a
partial wave expansion calculation. Results for 208Pb, 40Ca, 48Ca, 66Ni and
90Zr are shown and discussed.


title: Formality of DG algebras (after Kaledin)

abstract:
  We provide proper foundations and proofs for the main results of [Ka]. The
results include a flat base change for formality and behavior of formality in
flat families of $A(\infty)$ and DG algebras.


title: On the realization of Symmetries in Quantum Mechanics

abstract:
  The aim of this paper is to give a simple, geometric proof of Wigner's
theorem on the realization of symmetries in quantum mechanics that clarifies
its relation to projective geometry. Although several proofs exist already, it
seems that the relevance of Wigner's theorem is not fully appreciated in
general. It is Wigner's theorem which allows the use of linear realizations of
symmetries and therefore guarantees that, in the end, quantum theory stays a
linear theory. In the present paper, we take a strictly geometrical point of
view in order to prove this theorem. It becomes apparent that Wigner's theorem
is nothing else but a corollary of the fundamental theorem of projective
geometry. In this sense, the proof presented here is simple, transparent and
therefore accessible even to elementary treatments in quantum mechanics.


title:
A Study of the Decays D^0 --> pi^- e^+ nu_e, D^0 --> K^- e^+ nu_e, D^+
  --> pi^0 e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

abstract:
  Using 1.8 million DDbar pairs and a neutrino reconstruction technique, we
have studied the decays D^0 -> K^- e^+ nu_e, D^0 -> pi^- e^+ nu_e, D^+ ->
Kbar^0 e^+ nu_e, and D^+ -> pi^0 e^+ nu_e. We find B(D^0 -> pi^- e^+ nu_e) =
0.299(11)(9)%, B(D^+ -> pi^0 e^+ nu_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e)
= 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%. In addition, form
factors are studied through fits to the partial branching fractions obtained in
five q^2 ranges. By combining our results with recent unquenched lattice
calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106).


title: On the Ambiguity of Spontaneously Broken Gauge Symmetry

abstract:
  Local gauge symmetries cannot break spontaneously, according to Elitzur's
theorem, but this leaves open the possibility of breaking some global subgroup
of the local gauge symmetry, which is typically the gauge symmetry remaining
after certain (e.g. Coulomb or Landau) gauge choices. We show that in an SU(2)
gauge-Higgs system such symmetries do indeed break spontaneously, but the
location of the breaking in the phase diagram depends on the choice of global
subgroup. The implication is that there is no unique broken gauge symmetry, but
rather many symmetries which break in different places. The problem is to
decide which, if any, of these gauge symmetry breakings is associated with a
transition between physically different, confining and non-confining phases.
Several proposals - Kugo-Ojima, Coulomb, and monopole condensate - are
discussed.


title:
Research progress of electronic properties of self-assembled
  semiconductor quantum dots

abstract:
  Self-assembled semiconductor quantum dot is a new type of artificially
designed and grown function material which exhibits quantum size effect,
quantum interference effect, surface effect, quantum tunneling-Coulumb-blockade
effect and nonlinear optical effect. Due to advantages like less crystal
defects and relatively simpler fabrication technology, that material may be of
important value in future nanoelectronic device researches. In the order of
vertical transport, lateral transport and charge storage, this paper gives a
brief introduction of recent advances in the electronic properties of that
material and an analysis of problems and perspectives.


title:
Analysis based on the Wavelet & Hilbert transforms applied to the full
  time series of interbeats, for a triad of failures at the heart

abstract:
  A tetra of sets which elements are time series of interbeats has been
obtained from the databank Physionet-MIT-BIH, corresponding to the following
failures at the humans' heart: Obstructive Sleep Apnea, Congestive Heart
Failure, and Atrial Fibrillation. Those times series has been analyzed
statistically using an already known technique based on the Wavelet and Hilbert
Transforms. That technique has been applied to the time series of interbeats
for 87 patients, in order to find out the dynamics of the heart. The size of
the times series varies around 7 to 24 h. while the kind of wavelet selected
for this study has been any one of: Daubechies, Biortoghonal, and Gaussian. The
analysis has been done for the complet set of scales ranging from: 1-128
heartbeats. Choosing the Biorthogonal wavelet: bior3.1, it is observed: (a)
That the time series hasn't to be cutted in shorter periods, with the purpose
to obtain the collapsing of the data, (b) An analytical, universal behavior of
the data, for the first and second diseases, but not for the third.


title: Phase Transitions in Finite Systems using Information Theory

abstract:
  (abridged) In this paper, we present the issues we consider as essential as
far as the statistical mechanics of finite systems is concerned. In particular,
we emphasis our present understanding of phase transitions in the framework of
information theory. Information theory provides a thermodynamically-consistent
treatment of finite, open, transient and expanding systems which are difficult
problems in approaches using standard statistical ensembles. As an example, we
analyze is the problem of boundary conditions, which in the framework of
information theory must also be treated statistically. We recall that out of
the thermodynamical limit the different ensembles are not equivalent and in
particular they may lead to dramatically different equation of states, in the
region of a first order phase transition. We recall the recent progresses
achieved in the understanding of first-order phase transition in finite
systems: the equivalence between the Yang-Lee theorem and the occurrence of
bimodalities in the intensive ensemble and the presence of inverted curvatures
of the thermodynamic potential of the associated extensive ensemble.


title: Dynamical synapses causing self-organized criticality in neural networks

abstract:
  We show that a network of spiking neurons exhibits robust self-organized
criticality if the synaptic efficacies follow realistic dynamics. Deriving
analytical expressions for the average coupling strengths and inter-spike
intervals, we demonstrate that networks with dynamical synapses exhibit
critical avalanche dynamics for a wide range of interaction parameters. We
prove that in the thermodynamical limit the network becomes critical for all
large enough coupling parameters. We thereby explain experimental observations
in which cortical neurons show avalanche activity with the total intensity of
firing events being distributed as a power-law.


title:
On a correspondence principle between discrete differential forms, graph
  structure and multi-vector calculus on symmetric lattices

abstract:
  Based on \cite{DH94}, we introduce a bijective correspondence between first
order differential calculi and the graph structure of the symmetric lattice
that allows one to encode completely the interconnection structure of the graph
in the exterior derivative. As a result, we obtain the Grassmannian character
of the lattice as well as the mutual commutativity between basic vector-fields
on the tangent space.
  This in turn gives several similarities between the Clifford setting and the
algebra of endomorphisms endowed by the graph structure, such as the hermitian
structure of the lattice as well as the Clifford-like algebra of operators
acting on the lattice. This naturally leads to a discrete version of Clifford
Analysis.

categories: math.CV hep-lat math-ph math.DG math.MP math.QA


title: Swift Follow-up Observations of INTEGRAL Sources of Unknown Nature

abstract:
  (Abridged) We made use of X-ray observations with the X-ray telescope
on-board the \swift observatory to refine the X-ray position to 3-5" accuracy
of 12 INTEGRAL sources, so as to further identify their counterpart at optical,
infrared, and radio wavelengths, to try to unveil their true nature. We then
searched the online catalogues (e.g. NED, SIMBAD, 2MASS, 2MASX, and NVSS) to
search for counterparts at other wavelengths. For all sources, we give a
refined X-ray position, provide X-ray spectral parameters, identify infrared
counterparts, and give magnitudes at optical and ultra violet wavelengths seen
with UVOT when observations are available. We confirm the nature of six sources
formerly suspected to be AGN (IGR J02343+3229, J13149+4422, J14579-4308,
J16385-2057, J18559+1535, J19378-0617). Our analysis first leads us to suggest
that IGR J09523-6231 and IGR J10147-6354 are AGN. While the former has recently
been confirmed as a Seyfert 1.5 AGN, we suggest the latter is a Seyfert 2. All
other sources may be Galactic sources, in which case their spectral shape may
suggest that they are X-ray binaries. In one case (IGR J19308+0530), the
Galactic nature is confirmed through the identification of an F8 star as the
counterpart. We favour a distance to the source not greater than 1 kpc. The
source is likely to be a neutron star XRB or a CV. We also report the discovery
of six serendipitous sources of unknown nature.


title: Semiclassical measures and the Schroedinger flow on Riemannian manifolds

abstract:
  In this article we study limits of Wigner distributions (the so-called
semiclassical measures) corresponding to sequences of solutions to the
semiclassical Schroedinger equation at times scales $\alpha_{h}$ tending to
infinity as the semiclassical parameter $h$ tends to zero (when $\alpha
_{h}=1/h$ this is equivalent to consider solutions to the non-semiclassical
Schreodinger equation). Some general results are presented, among which a weak
version of Egorov's theorem that holds in this setting. A complete
characterization is given for the Euclidean space and Zoll manifolds (that is,
manifolds with periodic geodesic flow) via averaging formulae relating the
semiclassical measures corresponding to the evolution to those of the initial
states. The case of the flat torus is also addressed; it is shown that
non-classical behavior may occur when energy concentrates on resonant
frequencies. Moreover, we present an example showing that the semiclassical
measures associated to a sequence of states no longer determines those of their
evolutions. Finally, some results concerning the equation with a potential are
presented.


title:
Final-state effects in the radio frequency spectrum of strongly
  interacting fermions

abstract:
  We model the impact of final state interactions on the radio frequency
spectrum of a strongly interacting two-component superfluid Fermi gas. In
addition to a broad asymmetric peak coming from the break-up of Cooper pairs we
find that, for appropriate parameters, one can observe a sharp symmetric
"bound-bound" spectral line coming from the conversion of Cooper pairs in one
channels to pairs/molecules in another.


title: Quantum Simulated Annealing

abstract:
  We develop a quantum algorithm to solve combinatorial optimization problems
through quantum simulation of a classical annealing process. Our algorithm
combines techniques from quantum walks, quantum phase estimation, and quantum
Zeno effect. It can be viewed as a quantum analogue of the discrete-time Markov
chain Monte Carlo implementation of classical simulated annealing. Our
implementation scales with the inverse of the square root of the minimum
spectral gap of the stochastic matrix used in the classical simulation. The
quantum algorithm outperforms the classical one, which scales with the inverse
of the gap.


title: The CH3SH molecule deposited on Cu(111) and deprotonation

abstract:
  We demonstrate for the first time that when a methanethiol adsorbed on the
regular Cu(111) surface, the dissociative structure is thermodynamically more
stable than the intact one. The computational results show that at low
temperature the methanethiol adsorbate prefers the atop site of the regular
Cu(111) surface. As the temperature is increased, the S-H bond is broken and
the methylthiolate favors the hollow sites. On the defected Cu(111) surface,
the dissociative configuration is still thermodynamically more stable than the
nondissociative one. The calculation indicates that the hydrogen initially
attached to the sulfur would like to form a bond with the copper surface rather
than desorb from it. Even though both copper and gold are the noble metal, the
stability of the methanethiol adsorption on the Cu(111) substrate is almost the
reverse of that on the Au(111).


title: The First-Order Genus of a Knot

abstract:
  We introduce a geometric invariant of knots in the three-sphere, called the
first-order genus, that is derived from certain 2-complexes called gropes, and
we show it is computable for many examples. While computing this invariant, we
draw some interesting conclusions about the structure of a general Seifert
surface for some knots.


title: An Exceptional Electroweak Model

abstract:
  We consider a gauge extension of the electroweak sector of the Standard Model
based on the group G_2 x SU(2)x U(1). The exceptional group G_2 is the smallest
rank two group that contains SU(3) as a subgroup; the SU(3) prediction sin^2
theta_w=1/4 follows approximately in this model if the couplings of the
additional SU(2) and U(1) factors are sufficiently large. We study the symmetry
breaking sector of the model, the bounds from precision electroweak constraints
and the mass spectrum of exotic gauge bosons that may be produced at future
colliders. We also discuss an SU(3) electroweak model in which a vector-like
sector is included explicitly to facilitate the decays of otherwise stable
exotic states. The models considered here represent plausible extensions of the
minimal SU(3) electroweak model with potentially distinctive TeV-scale
phenomenology.


title:
Generalized parton distributions of the pion in chiral quark models and
  their QCD evolution

abstract:
  We evaluate Generalized Parton Distributions of the pion in two chiral quark
models: the Spectral Quark Model and the Nambu-Jona-Lasinio model with a
Pauli-Villars regularization. We proceed by the evaluation of double
distributions through the use of a manifestly covariant calculation based on
the alpha representation of propagators. As a result polynomiality is
incorporated automatically and calculations become simple. In addition,
positivity and normalization constraints, sum rules and soft pion theorems are
fulfilled. We obtain explicit formulas, holding at the low-energy quark-model
scale. The expressions exhibit no factorization in the t-dependence. The QCD
evolution of those parton distributions is carried out to experimentally or
lattice accessible scales. We argue for the need of evolution by comparing the
Parton Distribution Function and the Parton Distribution Amplitude of the pion
to the available experimental and lattice data, and confirm that the
quark-model scale is low, about 320 MeV.


title: Hankel operators that commute with second-order differential operators

abstract:
  Suppose that $\Gamma$ is a continuous and self-adjoint Hankel operator on
$L^2(0, \infty)$ and that $Lf=-(d/dx(a(x)df/dx))+b(x)f(x)$ with $a(0)=0$. If
$a$ and $b$ are both quadratic, hyperbolic or trigonometric functions, and
$\phi$ satisfies a suitable form of Gauss's hypergeometric equation, or the
confluent hypergeometric equation, then $L\Gamma =\Gamma L$. The paper
catalogues the commuting pairs $\Gamma$ and $L$, including important cases in
random matrix theory. There are also results proving rapid decay of the
singular numbers of Hankel integral operators with kernels that are analytic
and of exponential decay in the right half plane.


title:
Characterization Of A Class Of Graphs Related To Pairs Of Disjoint
  Matchings

abstract:
  For a given graph consider a pair of disjoint matchings the union of which
contains as many edges as possible. Furthermore, consider the relation of the
cardinalities of a maximum matching and the largest matching in those pairs. It
is known that this relation does not exceed 5/4 for any graph. We characterize
the class of graphs for which this relation is precisely 5/4. Our
characterization implies that these graphs contain a spanning subgraph, every
component of which is the minimal graph of this class.


title: Concurrence and negativity as distances

abstract:
  In this report we consider the three dimensional subset of the space of
states of two qubits that may be written in the so called standard form. For
those states we show that different measures of entanglement, specifically
concurrence, negativity and the Hilbert-Schmidt distance are proportional to
the euclidean distance between the point representing the state in the three
dimensional parameter space and the set of separable states.


title: Automating Renormalization of Quantum Field Theories

abstract:
  We give an overview of state-of-the-art multi-loop Feynman diagram
computations, and explain how we use symbolic manipulation to generate
renormalized integrals that are then evaluated numerically. We explain how we
automate BPHZ renormalization using "henges" and "sectors", and give a brief
description of the symbolic tensor and Dirac gamma-matrix manipulation that is
required. We shall compare the use of general computer algebra systems such as
Maple with domain-specific languages such as
  FORM, highlighting in particular memory management issues.


title:
Tunneling Study of the Charge-Ordering Gap on the Surface of
  La$_{0.350}$Pr$_{0.275}$Ca$_{0.375}$MnO$_3$ Thin Films

abstract:
  Variable temperature scanning tunneling microscopy/spectroscopy studies on
(110) oriented epitaxial thin films of
La$_{0.350}$Pr$_{0.275}$Ca$_{0.375}$MnO$_3$ are reported in the temperature
range of 77 to 340 K. The films, grown on lattice matched NdGaO$_3$ substrates,
show a hysteretic metal-insulator transition in resistivity at 170 K. The
topographic STM images show step-terrace morphology while the conductance
images display a nearly homogeneous surface. The normalized conductance spectra
at low temperatures (T$<$150 K) show an energy gap of 0.5 eV while for
T$\geq$180 K a gap of 0.16 eV is found from the activated behavior of the zero
bias conductance. The presence of energy gap and the absence of phase
separation on the surface over more than 2 $\mu$m$\times$2 $\mu$m area
contradicts the metallic behavior seen in resistivity measurements at low
temperatures. We discuss the measured energy gap in terms of the stabilization
of the insulating CO phase at the film surface.


title:
Taibleson Operators, p-adic Parabolic Equations and Ultrametric
  Diffusion

abstract:
  We give a multimensional version of the p-adic heat equation, and show that
its fundamental solution is the transition density of a Markov process.


title:
Ab initio Equation of State data for hydrogen, helium, and water and the
  internal structure of Jupiter

abstract:
  The equation of state of hydrogen, helium, and water effects interior
structure models of giant planets significantly. We present a new equation of
state data table, LM-REOS, generated by large scale quantum molecular dynamics
simulations for hydrogen, helium, and water in the warm dense matter regime,
i.e.for megabar pressures and temperatures of several thousand Kelvin, and by
advanced chemical methods in the complementary regions. The influence of
LM-REOS on the structure of Jupiter is investigated and compared with
state-of-the-art results within a standard three-layer model consistent with
astrophysical observations of Jupiter. Our new Jupiter models predict an
important impact of mixing effects of helium in hydrogen with respect to an
altered compressibility and immiscibility.


title:
A Study of the Semileptonic Charm Decays D^0 --> pi^- e^+ nu_e, D^+ -->
  pi^0 e^+ nu_e, D^0 --> K^- e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

abstract:
  Using a sample of 1.8 million DDbar meson pairs collected at the psi(3770)
with the CLEO-c detector, we study the semileptonic decays D^0 -> pi^- e^+
nu_e, D^+ -> pi^0 e^+ \nu_e, D^0 -> K^- e^+ \nu_e, and D^+ -> Kbar^0 e^+ nu_e.
For the total branching fractions we find B(D^0 -> pi^- e^+ \nu_e) =
0.299(11)(9)%, B(D^+ -> pi^0 e^+ \nu_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+
nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%, where the
first error is statistical and the second systematic. In addition, form factors
are studied through fits to the partial branching fractions obtained in five
q^2 ranges. By combining our results with recent unquenched lattice
calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106),
where the final error is theoretical.


title: A second look at N=1 supersymmetric AdS_4 vacua of type IIA supergravity

abstract:
  We show that a class of type IIA vacua recently found within the N=4
effective approach corresponds to compactification on Ads_4 \times S^3 \times
S^3/Z_2^3. The results obtained using the effective method completely match the
general ten-dimensional analysis for the existence of N=1 warped
compactifications on Ads_4 \times M_6. In particular, we verify that the
internal metric is nearly-Kahler and that for specific values of the parameters
the Bianchi identity of the RR 2-form is fulfilled without sources. For another
range of parameters, including the massless case, the Bianchi identity is
satisfied when D6-branes are introduced. Solving the tadpole cancellation
conditions in D=4 we are able to find examples of appropriate sets of branes.
In the second part of this paper we describe how an example with internal space
CP^3 but with non nearly-Kahler metric fits into the general analysis of flux
vacua.


title:
Theoretical Interest in B-Meson Physics at the B factories, Tevatron and
  the LHC

abstract:
  We review the salient features of $B$-meson physics, with particular emphasis
on the measurements carried out at the $B$-factories and Tevatron, theoretical
progress in understanding these measurements in the context of the standard
model, and anticipation at the LHC. Topics discussed specifically are the
current status of the Cabibbo-Kobayashi-Maskawa matrix, the CP-violating
phases, rare radiative and semileptonic decays, and some selected non-leptonic
two-body decays of the $B$ mesons.


title:
Charged Particle Stopping Power Effects on Ignition: Some Results from
  an Exact Calculation

abstract:
  A completely rigorous first-principles calculation of the charged particle
stopping power has recently been performed by Brown, Preston, and Singleton
(BPS). This calculation is exact to leading and next-to-leading order in the
plasma number density, including an exact treatment of two-body quantum
scattering. The BPS calculation is therefore extremely accurate in the plasma
regime realized during the ignition and burn of an inertial confinement fusion
capsule. For deuterium-tritium fusion, the 3.5 MeV alpha particle range tends
to be 20-30% longer than most models in the literature have predicted, and the
energy deposition into the ions tends to be smaller. Preliminary numerical
simulations indicate that this increases the rho-R required to achieve
ignition.


title: Opinion Dynamics in an Open Community

abstract:
  We here discuss the process of opinion formation in an open community where
agents are made to interact and consequently update their beliefs. New actors
(birth) are assumed to replace individuals that abandon the community (deaths).
This dynamics is simulated in the framework of a simplified model that accounts
for mutual affinity between agents. A rich phenomenology is presented and
discussed with reference to the original (closed group) setting. Numerical
findings are supported by analytical calculations.


title: Some questions to experimental gravity

abstract:
  The interpretations of solutions of Einstein field's equations led to the
prediction and the observation of physical phenomena which confirm the
important role of general relativity, as well as other relativistic theories in
physics. In this connection, the following questions are of interest and
importance: whether it is possible to solve the gauge problem and of its
physical significance, which one of the solutions gives the right description
of the observed values, how to clarify the physical meaning of the coordinates
which is unknown a priori, and why applying the same physical requirements in
different gauge fixing, we obtain different linear approximations. We discuss
some of the problems involved and point out several open problems. The paper is
written mainly for pedagogical purposes.


title:
Gauged Supergravities from Twisted Doubled Tori and Non-Geometric String
  Backgrounds

abstract:
  We propose a universal geometric formulation of gauged supergravity in terms
of a twisted doubled torus. We focus on string theory (M-theory) reductions
with generalized Scherk-Schwarz twists residing in the O(n,n) (E_{7(7)})
duality group. The set of doubled geometric fluxes, associated with the duality
twists and identified naturally with the embedding tensor of gauged
supergravity, captures all known fluxes, i.e. physical form fluxes, ordinary
geometric fluxes, as well as their non-geometric counterparts. Furthermore, we
propose a prescription for obtaining the effective geometry embedded in the
string theory twisted doubled torus or in the M-theory megatorus and apply it
for several models of geometric and non-geometric flux compactifications.


title: Kernels and Ensembles: Perspectives on Statistical Learning

abstract:
  Since their emergence in the 1990's, the support vector machine and the
AdaBoost algorithm have spawned a wave of research in statistical machine
learning. Much of this new research falls into one of two broad categories:
kernel methods and ensemble methods. In this expository article, I discuss the
main ideas behind these two types of methods, namely how to transform linear
algorithms into nonlinear ones by using kernel functions, and how to make
predictions with an ensemble or a collection of models rather than a single
model. I also share my personal perspectives on how these ideas have influenced
and shaped my own research. In particular, I present two recent algorithms that
I have invented with my collaborators: LAGO, a fast kernel algorithm for
unbalanced classification and rare target detection; and Darwinian evolution in
parallel universes, an ensemble method for variable selection.


title:
Perturbations of Schwarzschild Black Holes in Chern-Simons Modified
  Gravity

abstract:
  We study perturbations of a Schwarzschild black hole in Chern-Simons modified
gravity. We begin by showing that Birkhoff's theorem holds for a wide family of
Chern-Simons coupling functions, a scalar field present in the theory that
controls the strength of the Chern-Simons correction to the Einstein-Hilbert
action. After decomposing the perturbations in spherical harmonics, we study
the linearized modified field equations and find that axial and polar modes are
coupled, in contrast to general relativity. The divergence of the modified
equations leads to the Pontryagin constraint, which forces the vanishing of the
Cunningham-Price-Moncrief master function associated with axial modes. We
analyze the structure of these equations and find that the appearance of the
Pontryagin constraint yields an overconstrained system that does not allow for
generic black hole oscillations. We illustrate this situation by studying the
case characterized by a canonical choice of the coupling function and
pure-parity perturbative modes. We end with a discussion of how to extend
Chern-Simons modified gravity to bypass the Pontryagin constraint and the
suppression of perturbations.


title: Detection of circumstellar CH2CHCN, CH2CN, CH3CCH and H2CS

abstract:
  We report on the detection of vinyl cyanide (CH2CHCN), cyanomethyl radical
(CH2CN), methylacetylene (CH3CCH) and thioformaldehyde (H2CS) in the C-rich
star IRC +10216. These species, which are all known to exist in dark clouds,
are detected for the first time in the circumstellar envelope around an AGB
star. The four molecules have been detected trough pure rotational transitions
in the course of a 3 mm line survey carried out with the IRAM 30-m telescope.
The molecular column densities are derived by constructing rotational
temperature diagrams. A detailed chemical model of the circumstellar envelope
is used to analyze the formation of these molecular species. We have found
column densities in the range 5 x 10^(12)- 2 x 10^(13) cm^(-2), which
translates to abundances relative to H2 of several 10^(-9). The chemical model
is reasonably successful in explaining the derived abundances through gas phase
synthesis in the cold outer envelope. We also find that some of these
molecules, CH2CHCN and CH2CN, are most probably excited trough infrared pumping
to excited vibrational states. The detection of these species stresses the
similarity between the molecular content of cold dark clouds and C-rich
circumstellar envelopes. However, some differences in the chemistry are
indicated by the fact that in IRC +10216 partially saturated carbon chains are
present at a lower level than those which are highly unsaturated, while in
TMC-1 both types of species have comparable abundances.


title:
Bayesian comparison of Post-Newtonian approximations of gravitational
  wave chirp signals

abstract:
  We estimate the probability of detecting a gravitational wave signal from
coalescing compact binaries in simulated data from a ground-based
interferometer detector of gravitational radiation using Bayesian model
selection. The simulated waveform of the chirp signal is assumed to be a
spin-less Post-Newtonian (PN) waveform of a given expansion order, while the
searching template is assumed to be either of the same Post-Newtonian family as
the simulated signal or one level below its Post-Newtonian expansion order.
Within the Bayesian framework, and by applying a reversible jump Markov chain
Monte Carlo simulation algorithm, we compare PN1.5 vs. PN2.0 and PN3.0 vs.
PN3.5 wave forms by deriving the detection probabilities, the statistical
uncertainties due to noise as a function of the SNR, and the posterior
distributions of the parameters. Our analysis indicates that the detection
probabilities are not compromised when simplified models are used for the
comparison, while the accuracies in the determination of the parameters
characterizing these signals can be significantly worsened, no matter what the
considered Post-Newtonian order expansion comparison is.


title: Supercooling and phase coexistence in cosmological phase transitions

abstract:
  Cosmological phase transitions are predicted by Particle Physics models, and
have a variety of important cosmological consequences, which depend strongly on
the dynamics of the transition. In this work we investigate in detail the
general features of the development of a first-order phase transition. We find
thermodynamical constraints on some quantities that determine the dynamics,
namely, the latent heat, the radiation energy density and the false-vacuum
energy density. Using a simple model with a Higgs field, we study numerically
the amount and duration of supercooling and the subsequent reheating and phase
coexistence. We analyze the dependence of the dynamics on the different
parameters of the model, namely, the energy scale, the number of degrees of
freedom and the couplings of the scalar field with bosons and fermions. We also
inspect the implications for the cosmological outcomes of the phase transition.


title: Moonshine elements in elliptic cohomology

abstract:
  This is a historical talk about the recent confluence of two lines of
research in equivariant elliptic cohomology, one concerned with connected Lie
groups, the other with the finite case. These themes come together in (what
seems to me remarkable) work of N. Ganter, relating replicability of
McKay-Thompson series to the theory of exponential cohomology operations.