title: Precise Charm and Bottom quark masses

abstract:
  New data for the total cross section sigma(e^+e^- --> hadrons) in the charm
and bottom threshold region are combined with an improved theoretical analysis,
which includes recent four-loop calculations, to determine the short distance
\bar{MS} charm and bottom quark masses. The final result for the
\bar{MS}-masses, m_c(3 GeV)=0.986(13) GeV and m_b(10 GeV)=3.609(25) GeV is
consistent with but significantly more precise than a similar previous study.


title: A direct experimental limit on neutron -- mirror neutron oscillations

abstract:
  In case a mirror world with a copy of our ordinary particle spectrum would
exist, the neutron n and its degenerate partner, the mirror neutron ${\rm n'}$,
could potentially mix and undergo ${\rm nn'}$ oscillations. The interaction of
an ordinary magnetic field with the ordinary neutron would lift the degeneracy
between the mirror partners, diminish the ${\rm n'}$-amplitude in the
n-wavefunction and, thus, suppress its observability. We report an experimental
comparison of ultracold neutron storage in a trap with and without superimposed
magnetic field. No influence of the magnetic field is found and, assuming
negligible mirror magnetic fields, a limit on the oscillation time $\tau_{\rm
nn'} > 103$ s (95% C.L.) is derived.


title:
Universal parametric correlations in the classical limit of quantum
  transport

abstract:
  Quantum corrections to transport through a chaotic ballistic cavity are known
to be universal. The universality not only applies to the magnitude of quantum
corrections, but also to their dependence on external parameters, such as the
Fermi energy or an applied magnetic field. Here we consider such parameter
dependence of quantum transport in a ballistic chaotic cavity in the
semiclassical limit obtained by sending Planck's constant to zero without
changing the classical dynamics of the open cavity. In this limit quantum
corrections are shown to have a universal parametric dependence which is not
described by random matrix theory.


title: An elementary proof of the convergence of Ricci flow on compact surfaces

abstract: This paper has been withdrawn by the author for further modification.


title:
A Massive Yang-Mills Theory based on the Nonlinearly Realized Gauge
  Group

abstract:
  We propose a subtraction scheme for a massive Yang-Mills theory realized via
a nonlinear representation of the gauge group (here SU(2)). It is based on the
subtraction of the poles in D-4 of the amplitudes, in dimensional
regularization, after a suitable normalization has been performed. Perturbation
theory is in the number of loops and the procedure is stable under iterative
subtraction of the poles. The unphysical Goldstone bosons, the Faddeev-Popov
ghosts and the unphysical mode of the gauge field are expected to cancel out in
the unitarity equation. The spontaneous symmetry breaking parameter is not a
physical variable. We use the tools already tested in the nonlinear sigma
model: hierarchy in the number of Goldstone boson legs and weak power-counting
property (finite number of independent divergent amplitudes at each order). It
is intriguing that the model is naturally based on the symmetry SU(2)_L local
times SU(2)_R global. By construction the physical amplitudes depend on the
mass and on the self-coupling constant of the gauge particle and moreover on
the scale parameter of the radiative corrections. The Feynman rules are in the
Landau gauge.


title: Localization and chiral symmetry in 2+1 flavor domain wall QCD

abstract:
  We present results for the dependence of the residual mass of domain wall
fermions (DWF) on the size of the fifth dimension and its relation to the
density and localization properties of low-lying eigenvectors of the
corresponding hermitian Wilson Dirac operator relevant to simulations of 2+1
flavor domain wall QCD. Using the DBW2 and Iwasaki gauge actions, we generate
ensembles of configurations with a $16^3\times 32$ space-time volume and an
extent of 8 in the fifth dimension for the sea quarks. We demonstrate the
existence of a regime where the degree of locality, the size of chiral symmetry
breaking and the rate of topology change can be acceptable for inverse lattice
spacings $a^{-1} \ge 1.6$ GeV.


title:
Coulomb Gas on the Keldysh Contour: Anderson-Yuval-Hamann representation
  of the Nonequilibrium Two Level System

abstract:
  The nonequilibrium tunnelling center model of a localized electronic level
coupled to a fluctuating two-state system and to two electronic reservoirs, is
solved via an Anderson-Yuval-Hamann mapping onto a plasma of alternating
positive and negative charges time-ordered along the two "Keldysh" contours
needed to describe nonequilibrium physics. The interaction between charges
depends both on whether their time separation is small or large compared to a
dephasing scale defined in terms of the chemical potential difference between
the electronic reservoirs and on whether their time separation is larger or
smaller than a decoherence scale defined in terms of the current flowing from
one reservoir to another. A renormalization group transformation appropriate to
the nonequilibrium problem is defined. An important feature is the presence in
the model of a new coupling, essentially the decoherence rate, which acquires
an additive renormalization similar to that of the energy in equilibrium
problems. The method is used to study interplay between the dephasing-induced
formation of independent resonances tied to the two chemical potentials and the
decoherence which cuts off the scaling and leads to effectively classical
long-time behavior. We determine the effect of departures from equilibrium on
the localization-delocalization phase transition.


title: Continuous quantum error correction for non-Markovian decoherence

abstract:
  We study the effect of continuous quantum error correction in the case where
each qubit in a codeword is subject to a general Hamiltonian interaction with
an independent bath. We first consider the scheme in the case of a trivial
single-qubit code, which provides useful insights into the workings of
continuous error correction and the difference between Markovian and
non-Markovian decoherence. We then study the model of a bit-flip code with each
qubit coupled to an independent bath qubit and subject to continuous
correction, and find its solution. We show that for sufficiently large
error-correction rates, the encoded state approximately follows an evolution of
the type of a single decohering qubit, but with an effectively decreased
coupling constant. The factor by which the coupling constant is decreased
scales quadratically with the error-correction rate. This is compared to the
case of Markovian noise, where the decoherence rate is effectively decreased by
a factor which scales only linearly with the rate of error correction. The
quadratic enhancement depends on the existence of a Zeno regime in the
Hamiltonian evolution which is absent in purely Markovian dynamics. We analyze
the range of validity of this result and identify two relevant time scales.
Finally, we extend the result to more general codes and argue that the
performance of continuous error correction will exhibit the same qualitative
characteristics.


title: On the motive of certain subvarieties of fixed flags

abstract:
  We compute de Chow motive of certain subvarieties of the flags manifold and
show that it is an Artin motive.


title:
Canonical structure of dynamical fluctuations in mesoscopic
  nonequilibrium steady states

abstract:
  We give the explicit structure of the functional governing the dynamical
density and current fluctuations for a mesoscopic system in a nonequilibrium
steady state. Its canonical form determines a generalised Onsager-Machlup
theory. We assume that the system is described as a Markov jump process
satisfying a local detailed balance condition such as typical for stochastic
lattice gases and for chemical networks. We identify the entropy current and
the traffic between the mesoscopic states as extra terms in the fluctuation
functional with respect to the equilibrium dynamics. The density and current
fluctuations are coupled in general, except close to equilibrium where their
decoupling explains the validity of entropy production principles.


title: Uniqueness of polynomial canonical representations

abstract:
  Let P(z) and Q(y) be polynomials of the same degree k>=1 in the complex
variables z and y, respectively. In this extended abstract we study the
non-linear functional equation P(z)=Q(y(z)), where y(z) is restricted to be
analytic in a neighborhood of z=0. We provide sufficient conditions to ensure
that all the roots of Q(y) are contained within the range of y(z) as well as to
have y(z)=z as the unique analytic solution of the non-linear equation. Our
results are motivated from uniqueness considerations of polynomial canonical
representations of the phase or amplitude terms of oscillatory integrals
encountered in the asymptotic analysis of the coefficients of mixed powers and
multivariable generating functions via saddle-point methods. Uniqueness shall
prove important for developing algorithms to determine the Taylor coefficients
of the terms appearing in these representations. The uniqueness of Levinson's
polynomial canonical representations of analytic functions in several variables
follows as a corollary of our one-complex variables results.


title: Strings as sigma models and in the tensionless limit

abstract:
  This thesis considers two different aspects of string theory, the tensionless
limit of the string and supersymmetric sigma models. The tensionless limit is
used to find a IIB supergravity background generated by a tensionless string.
Quantization of the tensionless string in a pp-wave background is performed and
the tensionless limit is found to commute with quantization. Further, the sigma
model with N=(2,2) extended world-sheet supersymmetry is considered and the
requirement on the target space to have a bi-Hermitean geometry is reviewed. It
is shown that the equivalence between bi-Hermitean geometry and generalized
Kahler follows, in this context, from the equivalence between the Lagrangian-
and Hamiltonian formulation of the model. Moreover, the explicit T-duality
transformation in the Hamiltonian formulation of the sigma model is constructed
and shown to be a symplectomorphism. Under certain assumptions, the amount of
extended supersymmetry present in the sigma model is shown to be preserved
under T-duality. Further, by requiring N=(2,2) extended supersymmetry in a
first order formulation of the sigma model an intriguing geometrical structure
arises and in a special case generalized complex geometry is found to be
contained in the new framework.


title: Five-dimensional vector-coupled supergravity on a manifold with boundary

abstract:
  We consider the bosonic and fermionic symmetries of five-dimensional Maxwell-
and Yang-Mills-Einstein supergravity theories on a spacetime with boundaries
(isomorphic to M x S1/Z2). Due to the appearance of the "Chern-Simons" term,
the classical action is not generally invariant under gauge and
supersymmetries. Once bulk vector fields are allowed to propagate on the
boundaries, there is an "inflow" governed by the rank-3 symmetric tensor that
defines the five-dimensional theories. We discuss the requirements that
invariance of the action imposes on new matter content and boundary conditions.


title: Water confined in nanopores: spontaneous formation of microcavities

abstract:
  Molecular Dynamics simulations of water confined in nanometer sized,
hydrophobic channels show that water forms localized cavities for pore diameter
~ 2.0 nm. The cavities present non-spherical shape and lay preferentially
adjacent to the confining wall inducing a peculiar form to the liquid exposed
surface. The regime of localized cavitation appears to be correlated with the
formation of a vapor layer, as predicted by the Lum-Chandler-Weeks theory,
implying partial filling of the pore.


title: Effects of Electron-Lattice Coupling on Charge Order in \theta-(ET)2X

abstract:
  Charge ordering accompanied by lattice distortion in quasi-two dimensional
organic conductors \theta-(ET)2X (ET=BEDT-TTF) is studied by using an extended
Hubbard model with Peierls-type electron-lattice couplings within the
Hartree-Fock approximation. It is found that the horizontal-stripe
charge-ordered state, which is experimentally observed in
\theta-(ET)2RbZn(SCN)4, is stabilized by the self-consistently determined
lattice distortion. Furthermore, in the presence of the anisotropy in
nearest-neighbor Coulomb interactions Vij, the horizontal charge order becomes
more stable than any other charge patterns such as diagonal, vertical and
3-fold-type states. At finite temperatures, we compare the free energies of
various charge-ordered states and find a first-order transition from a metallic
state with 3-fold charge order to the insulating state with the horizontal
charge order. The role of lattice degrees of freedom in the realization of the
horizontal charge order and the relevance to experiments on \theta-(ET)2X are
discussed.


title:
Decoherence of many-spin systems in NMR: From molecular characterization
  to an environmentally induced quantum dynamical phase transition

abstract:
  The control of open quantum systems has a fundamental relevance for fields
ranging from quantum information processing to nanotechnology. Typically, the
system whose coherent dynamics one wants to manipulate, interacts with an
environment that smoothly degrades its quantum dynamics. Thus, a precise
understanding of the inner mechanisms of this process, called "decoherence", is
critical to develop strategies to control the quantum dynamics. In this thesis
we solved the generalized Liouville-von Neumann quantum master equation to
obtain the dynamics of many-spin systems interacting with a spin bath. We also
solve the spin dynamics within the Keldysh formalism. Both methods lead to
identical solutions and together gave us the possibility to obtain numerous
physical predictions that contrast well with Nuclear Magnetic Resonance
experiments. We applied these tools for molecular characterizations,
development of new numerical methodologies and the control of quantum dynamics
in experimental implementations. But, more important, these results contributed
to fundamental physical interpretations of how quantum dynamics behaves in open
systems. In particular, we found a manifestation of an environmentally induced
quantum dynamical phase transition.


title:
The Use of ITIL for Process Optimisation in the IT Service Centre of
  Harz University, exemplified in the Release Management Process

abstract:
  This paper details the use of the IT Infrastructure Library Framework (ITIL)
for optimising process workflows in the IT Service Centre of Harz University in
Wernigerode, Germany, exemplified by the Release Management Process. It is
described, how, during the course of a special ITIL project, the As-Is-Status
of the various original processes was documented as part of the process life
cycle and then transformed in the To-Be-Status, according to the ITIL Best
Practice Framework. It is also shown, how the ITIL framework fits into the
four-layered-process model, that could be derived from interviews with the
universities IT support staff, and how the various modified processes
interconnect with each other to form a value chain. The paper highlights the
final results of the project and gives an outlook on the future use of ITIL as
a business modelling tool in the IT Service Centre of Harz University. It is
currently being considered, whether the process model developed during the
project could be used as a reference model for other university IT centres.


title:
Theta dependence of the vacuum energy in the SU(3) gauge theory from the
  lattice

abstract:
  We report on a precise computation of the topological charge distribution in
the SU(3) Yang--Mills theory. It is carried out on the lattice with high
statistics Monte Carlo simulations by employing the definition of the
topological charge suggested by Neuberger's fermions. We observe significant
deviations from a Gaussian distribution. Our results disfavour the theta
behaviour of the vacuum energy predicted by instanton models, while they are
compatible with the expectation from the large Nc expansion.


title: The status of the heavy quark systems

abstract:
  We review various inequalities on the order and the spacing of energy levels,
wave function at the origin, etc... which were obtained since 1977 in the
framework of the Schrodinger equation and applied to quarkonium and also to
muonic atoms and alcaline atoms. We also present a fit of mesons and baryons
made of b, c, s quarks and antiquarks, keeping the 1981 parameters and
comparing with present experimental data.


title:
Nonlinear evolution of a morphological instability in a strained
  epitaxial film

abstract:
  A strained epitaxial film deposited on a deformable substrate undergoes a
morphological instability relaxing the elastic energy by surface diffusion. The
nonlinear and nonlocal dynamical equations of such films with wetting
interactions are derived and solved numerically in two and three dimensions.
Above some critical thickness, the surface evolves towards an array of islands
separated by a wetting layer. The island chemical potential decreases with its
volume, so that the system experiences a non-interrupted coarsening described
by power laws with a marked dimension dependence.


title: In silico evidence of the relationship between miRNAs and siRNAs

abstract:
  Both short interfering RNAs (siRNAs) and microRNAs (miRNAs) mediate the
repression of specific sequences of mRNA through the RNA interference pathway.
In the last years several experiments have supported the hypothesis that siRNAs
and miRNAs may be functionally interchangeable, at least in cultured cells. In
this work we verify that this hypothesis is also supported by a computational
evidence. We show that a method specifically trained to predict the activity of
the exogenous siRNAs assigns a high silencing level to experimentally
determined human miRNAs. This result not only supports the idea of siRNAs and
miRNAs equivalence but indicates that it is possible to use computational tools
developed using synthetic small interference RNAs to investigate endogenous
miRNAs.


title: Single-Spin Asymmetries in Inclusive and Exclusive Hadronic Processes

abstract:
  We investigate the single-spin asymmetries in inclusive and exclusive
processes of electron-proton scattering and electron-positron annihilation. In
the decomposition of hadronic tensor, a Lorentz symmetric spin-dependent term
is generally present. The existence of such a term implies single-spin
asymmetries in these processes and these single-spin asymmetries for baryons
can be understood in a unified manner. We argue that it is important to measure
the single-spin asymmetries in both inclusive and exclusive processes for the
$\Lambda$ production at the present B-factories. This will lead to the first
measurement of the structure function of the symmetric spin-dependent hadronic
tensor in these processes.


title:
The inevitable nonlinearity of quantum gravity falsifies the many-worlds
  interpretation of quantum mechanics

abstract:
  There are fundamental reasons as to why there should exist a reformulation of
quantum mechanics which does not refer to a classical spacetime manifold. It
follows as a consequence that quantum mechanics as we know it is a limiting
case of a more general nonlinear quantum theory, with the nonlinearity becoming
significant at the Planck mass/energy scale. This nonlinearity is responsible
for a dynamically induced collapse of the wave-function, during a quantum
measurement, and it hence falsifies the many-worlds interpretation of quantum
mechanics. We illustrate this conclusion using a mathematical model based on a
generalized Doebner-Goldin equation. The non-Hermitian part of the Hamiltonian
in this norm-preserving, nonlinear, Schrodinger equation dominates during a
quantum measurement, and leads to a breakdown of linear superposition.


title:
Non-Markovian Stochastic Liouville equation and its Markovian
  representation. Extensions of the continuous time random walk approach

abstract:
  Some specific features and extensions of the continuous time random walk
(CTRW) approach are analyzed in detail within the Markovian representation (MR)
and CTRW-based non-Markovian stochastic Liouville equation (SLE). In the MR
CTRW processes are represented by multidimensional Markovian ones. In this
representation the probability distribution function (PDF) W(t) of fluctuation
renewals is associated with that of reoccurrences in a certain jump state of
some Markovian controlling process. Within the MR the non-Markovian SLE, which
describes the effect of CTRW-like noise on relaxation of dynamic and stochastic
systems, is generalized to take into account the influence of relaxing systems
on statistical properties of noise. The generalized non-Markovian SLE is
applied to study two modifications of the CTRW approach. One of them considers
the cascaded CTRWs in which the controlling process is actually CTRW-like one
controlled by another CTRW process, controlled in turn by the third one, etc.
Within the MR simple expression for the PDF W(t) of total controlling process
is obtained in terms of Markovian variants of controlling PDFs in the cascade.
The expression is shown to be especially simple and instructive in the case of
anomalous processes determined by long time tailed W(t). The cascaded CTRWs can
model the effect of complexity of a system on relaxation kinetics (in glasses,
fractals, branching media, ultrametric structures, etc.). Another
CTRW-modification describes the kinetics of processes governed by fluctuating
W(t). Within the MR the problem is analyzed in a general form without
restrictive assumptions on correlations of PDFs of consecutive renewals. The
analysis shows that W(t) can strongly affect the kinetics of the process.
Possible manifestations of this effect are discussed.


title: First season QUaD CMB temperature and polarization power spectra

abstract:
  QUaD is a bolometric CMB polarimeter sited at the South Pole, operating at
frequencies of 100 and 150 GHz. In this paper we report preliminary results
from the first season of operation (austral winter 2005). All six CMB power
spectra are presented derived as cross spectra between the 100 and 150 GHz maps
using 67 days of observation in a low foreground region of approximately 60
square degrees. This data is a small fraction of the data acquired to date. The
measured spectra are consistent with the LCDM cosmological model. We perform
jackknife tests which indicate that the observed signal has negligible
contamination from instrumental systematics. In addition by using a frequency
jackknife we find no evidence for foreground contamination.


title: A Three-Flavor AdS/QCD Model with a Back-Reacted Geometry

abstract:
  A fully back-reaction geometry model of AdS/QCD including the strange quark
is described. We find that with the inclusion of the strange quark the impact
on the metric is very small and the final predictions are changed only
negligibly.


title: Periodic orbits in the case of a zero eigenvalue

abstract:
  We will show that if a dynamical system has enough constants of motion then a
Moser-Weinstein type theorem can be applied for proving the existence of
periodic orbits in the case when the linearized system is degenerate.


title: Geometric control theory I: mathematical foundations

abstract:
  A geometric setup for control theory is presented. The argument is developed
through the study of the extremals of action functionals defined on piecewise
differentiable curves, in the presence of differentiable non-holonomic
constraints. Special emphasis is put on the tensorial aspects of the theory. To
start with, the kinematical foundations, culminating in the so called
variational equation, are put on geometrical grounds, via the introduction of
the concept of infinitesimal control . On the same basis, the usual
classification of the extremals of a variational problem into normal and
abnormal ones is also rationalized, showing the existence of a purely
kinematical algorithm assigning to each admissible curve a corresponding
abnormality index, defined in terms of a suitable linear map. The whole
machinery is then applied to constrained variational calculus. The argument
provides an interesting revisitation of Pontryagin maximum principle and of the
Erdmann-Weierstrass corner conditions, as well as a proof of the classical
Lagrange multipliers method and a local interpretation of Pontryagin's
equations as dynamical equations for a free (singular) Hamiltonian system. As a
final, highly non-trivial topic, a sufficient condition for the existence of
finite deformations with fixed endpoints is explicitly stated and proved.


title: Lasso type classifiers with a reject option

abstract:
  We consider the problem of binary classification where one can, for a
particular cost, choose not to classify an observation. We present a simple
proof for the oracle inequality for the excess risk of structural risk
minimizers using a lasso type penalty.


title:
Graviton localization and Newton's law for brane models with a
  non-minimally coupled bulk scalar field

abstract:
  Brane world models with a non-minimally coupled bulk scalar field have been
studied recently. In this paper we consider metric fluctuations around an
arbitrary gravity-scalar background solution, and we show that the
corresponding spectrum includes a localized zero mode which strongly depends on
the profile of the background scalar field. For a special class of solutions,
with a warp factor of the RS form, we solve the linearized Einstein equations,
for a point-like mass source on the brane, by using the brane bending
formalism. We see that general relativity on the brane is recovered only if we
impose restrictions on the parameter space of the models under consideration.


title: The issue of photons in dielectrics: Hamiltonian viewpoint

abstract:
  The definition of the photon in the vacuum of general relativity provided by
Kermack et al. and by Synge is extended to nondispersive, nonhomogeneous,
isotropic dielectrics in arbitrary motion by Hamiltonian methods that rely on
Gordon's effective metric. By these methods the old dilemma, whether the
momentum-energy vector of the photon in dielectrics is timelike or spacelike in
character, is shown to reappear under a novel guise.


title: Instantons and Holomorphic Couplings in Intersecting D-brane Models

abstract:
  We clarify certain aspects and discuss extensions of the recently introduced
string D-instanton calculus (hep-th/0609191). The one-loop determinants are
related to one-loop open string threshold corrections in intersecting D6-brane
models. Utilising a non-renormalisation theorem for the holomorphic Wilsonian
gauge kinetic functions, we derive a number of constraints for the moduli
dependence of the matter field Kaehler potentials of intersecting D6-brane
models on the torus. Moreover, we compute string one-loop corrections to the
Fayet-Iliopoulos terms on the D6-branes finding that they are proportional to
the gauge threshold corrections. Employing these results, we discuss the issue
of holomorphy for E2-instanton corrections to the superpotential. Eventually,
we discuss E2-instanton corrections to the gauge kinetic functions and the
FI-terms.


title: Desorption of hot molecules from photon irradiated interstellar ices

abstract:
  We present experimental measurements of photodesorption from ices of
astrophysical relevance. Layers of benzene and water ice were irradiated with a
laser tuned to an electronic transition in the benzene molecule. The
translational energy of desorbed molecules was measured by time-of-flight (ToF)
mass spectrometry. Three distinct photodesorption processes were identified - a
direct adsorbate-mediated desorption producing benzene molecules with a
translational temperature of around 1200 K, an indirect adsorbate-mediated
desorption resulting in water molecules with a translational temperature of
around 450 K, and a substrate-mediated desorption of both benzene and water
producing molecules with translational temperatures of around 530 K and 450 K
respectively. The translational temperature of each population of desorbed
molecules is well above the temperature of the ice matrix. The implications for
gas-phase chemistry in the interstellar medium are discussed.


title: Regular homogeneous T-models with vacuum dark fluid

abstract:
  We present the class of regular homogeneous T-models with vacuum dark fluid,
associated with a variable cosmological term. The vacuum fluid is defined by
the symmetry of its stress-energy tensor, i.e., its invariance under Lorentz
boosts in a distinguished spatial direction (p_j=-\rho), which makes this fluid
essentially anisotropic and allows its density to evolve. Typical features of
homogeneous regular T-models are: the existence of a Killing horizon; beginning
of the cosmological evolution from a null bang at the horizon; the existence of
a regular static pre-bang region visible to cosmological observers; creation of
matter from anisotropic vacuum, accompanied by very rapid isotropization. We
study in detail the spherically symmetric regular T-models on the basis of a
general exact solution for a mixture of the vacuum fluid and dustlike matter
and apply it to give numerical estimates for a particular model which
illustrates the ability of cosmological T-models to satisfy the observational
constraints.


title: Coordinate Bethe Ansatz for the String S-Matrix

abstract:
  We use the coordinate Bethe ansatz approach to derive the nested Bethe
equations corresponding to the recently found S-matrix for strings in AdS5 x
S5, compatible with centrally extended su(2|2) symmetry.


title: Energy protection arguments fail in the interaction picture

abstract:
  Spin Hamiltonians with degenerate ground states are one potential system for
the storage of quantum information at low temperatures. Trapped ions can be
used to simulate the dynamics of these Hamiltonians, but the
coherence-preserving properties will be lost. This illustrates that a quantum
simulation performed in an interaction frame will not thermalize with its
environment.


title: Normalization of twisted Alexander invariants

abstract:
  Twisted Alexander invariants of knots are well-defined up to multiplication
of units. We get rid of this multiplicative ambiguity via a combinatorial
method and define normalized twisted Alexander invariants. We then show that
the invariants coincide with sign-determined Reidemeister torsion in a
normalized setting, and refine the duality theorem. We further obtain necessary
conditions on the invariants for a knot to be fibered, and study behavior of
the highest degrees of the invariants.


title: Measurement of the gluon polarisation at COMPASS

abstract:
  COMPASS experiment measurements of the gluon polarisation in nucleon,
DeltaG/G are reviewed. Two different approaches based on tagging the Photon
Gluon Fusion process are described. They rely on the open charm meson or
high-p_T hadron pairs detection.


title: Bekenstein Bound and Spectral Geometry

abstract:
  In this letter it is proposed to study the Bekenstein's $\xi(4)$ calculation
of the $S/E$ bound for more general geometries. It is argued that, using some
relations among eigenvalues obtained in the context of Spectral Geometry, it is
possible to estimate $\xi(4)$ without an exact analytical knowledge of the
spectrum. Finally it is claimed that isospectrality can define a class of
domains with the same ratio $S/E$.


title: Reconstruction of the photon distribution in a micromaser

abstract:
  We suggest an iterative, maximum-likelihood-based, method to reconstruct the
photon number distribution of the steady state cavity field of a micromaser
starting from the statistics of the atoms leaving the cavity after the
interaction. The scheme is based on measuring the atomic populations of probe
atoms for different interaction times and works effectively using a small
number of atoms and a limited sampling of the interaction times. The method has
been tested by numerically simulated experiments showing that it may be
reliably used in any micromaser regime leading to high-fidelity reconstructions
for single-peaked distributions as well as for double-peaked ones and for
trapping states.


title: Spin Diode Based on Fe/MgO Double Tunnel Junction

abstract:
  We demonstrate a spin diode consisting of a semiconductor free nano-scale
Fe/MgO-based double tunnel junction. The device exhibits a near perfect
spin-valve effect combined with a strong diode effect. The mechanism consistent
with our data is resonant tunneling through discrete states in the middle
ferromagnetic layer sandwiched by tunnel barriers of different spin-dependent
transparency. The observed magneto-resistance is record high, ~4000%,
essentially making the structure an on/off spin-switch. This, combined with the
strong diode effect, ~100, offers a new device that should be promising for
such technologies as magnetic random access memory and re-programmable logic.


title: A note on the topological order of noncommutative Hall fluids

abstract:
  We evaluate the ground state degeneracy of noncommutative Chern-Simons models
on the two-torus, a quantity that is interpreted as the "topological order" of
associated phases of Hall fluids. We define the noncommutative theory via
T-duality from an ordinary Chern-Simons model with non-abelian 't Hooft
magnetic fluxes. Motivated by this T-duality, we propose a discrete family of
noncommutative, non-abelian fluid models, arising as a natural generalization
of the standard noncommutative Chern-Simons effective models. We compute the
topological order for these universality classes, and comment on their possible
microscopic interpretation.


title: Singular link Floer homology

abstract:
  We define a grid presentation for singular links i.e. links with a finite
number of rigid transverse double points. Then we use it to generalize link
Floer homology to singular links. Besides the consistency of its definition, we
prove that this homology is acyclic under some conditions which naturally make
its Euler characteristic vanish.


title:
X-ray emission from PSR J1809-1917 and its pulsar wind nebula, possibly
  associated with the TeV gamma-ray source HESS J1809-193

abstract:
  We detected X-ray emission from the 50-kyr-old pulsar J1809-1917 and resolved
its pulsar wind nebula (PWN) with Chandra. The pulsar spectrum fits PL+BB model
with the photon index of 1.2 and the BB temperature of 2 MK for n_{H}=0.7\times
10^{22} cm^{-2}. The luminosities are(4\pm 1)\times 10^{31} ergs s^{-1} for the
PL component (in the 0.5-8 keV band) and ~1\times 10^{32} ergs s^{-1} for the
BB component (bolometric) at a plausible distance of 3.5 kpc. The bright inner
PWN component of a 3''\times12'' size is elongated in the north-south
direction, with the pulsar close to its south end. This component is immersed
in a larger (20''\times40''), similarly elongated outer PWN component of lower
surface brightness. The elongated shape of the compact PWN can be explained by
the ram pressure confinement of the pulsar wind due to the supersonic motion of
the pulsar. The PWN spectrum fits a PL model with photon index of 1.4\pm0.1 and
0.5-8 keV luminosity of 4\times10^{32} ergs s^{-1}. The compact PWN appears to
be inside a large-scale (~4'\times4') emission more extended to the south of
the pulsar, i.e. in the direction of the alleged pulsar motion. To explain the
extended X-ray emission ahead of the moving pulsar, one has to invoke strong
intrinsic anisotropy of the pulsar wind or assume that this emission comes from
a relic PWN swept by the asymmetrical reverse SNR shock. The pulsar and its PWN
are located within the extent of the unidentified TeV source HESS J1809-193
whose brightest part is offset by ~8' to the south of the pulsar, i.e. in the
same direction as the large-scale X-ray emission. Although the association
between J1809-1917 and HESS J1809-193 is plausible, an alternative source of
relativistic electrons powering HESS J1809-193 might be the serendipitously
discovered X-ray source CXOU J180940.7-192544.


title:
The integrals in Gradshteyn and Ryzhik. Part 5: Some trigonometric
  integrals

abstract:
  We present evalauations and provide proofs of definite integrals involving
the function x^p cos^n x. These formulae are generalizations of 3.761.11 and
3.822.1, among others, in the classical table of integrals by I. S. Gradshteyn
and I. M. Ryzhik.


title:
A Covariant Road to Spatial Averaging in Cosmology : Scalar Corrections
  to the Cosmological Equations

abstract:
  A consistent approach to Cosmology requires an explicit averaging of the
Einstein equations, to describe a homogeneous and isotropic geometry. Such an
averaging will in general modify the Einstein equations. The averaging
procedure due to Buchert has attracted considerable attention recently since it
offers the tantalizing hope of explaining the phenomenon of dark energy through
such corrections. This approach has been criticized, however, on the grounds
that its effects may be gauge artifacts. We apply the fully covariant formalism
of Zalaletdinov's Macroscopic Gravity and show that, after making some
essential gauge choices, the Cosmological equations receive \emph{spacetime
scalar} corrections which are therefore observable in principle, and further,
that the broad structure of these corrections is \emph{identical} to those
derived by Buchert.


title:
Late-time emission of type Ia supernovae: optical and near-infrared
  observations of SN 2001el

abstract:
  We present optical and near-infrared light curves of SN 2001el from 310 to
445 days past maximum light, obtained with the Very Large Telescope. The
late-time optical (UBVRI) light curves decay in a nearly linear fashion with
decay time scales of 1.43\pm0.14, 1.43\pm0.06, 1.48\pm0.06, 1.45\pm0.07, and
1.03\pm0.07 magnitudes (per hundred days) in the U, B, V, R and I bands,
respectively. In contrast, in the near-infrared (JHKs) bands the time evolution
of the flux appears to be nearly constant at these epochs. We measure decline
rates (per hundred days) of 0.19\pm0.10 and 0.17\pm0.11 magnitudes in the J and
H bands, respectively. We construct a UVOIR light curve, and find that the
late-time luminosity has a decay time scale nearly consistent with complete
depostion of positron kinetic energy. The late-time light curves of the normal
type Ia SN 2001el demonstrate the increased importance of the near-infrared
contribution. This was previously observed in the peculiar SN 2000cx, and the
results for SN 2001el thus ensure that the conclusions previously based on a
single peculiar event are applicable to normal type Ia supernovae. The measured
late-time UVOIR decline rate suggests that a majority of the positrons are
trapped within the ejecta. This results does not favor the predictions of a
weak and/or radially combed magnetic field configuration.


title:
Intermediate-statistics quantum bracket, coherent state, oscillator, and
  representation of angular momentum (su(2)) algebra

abstract:
  In this paper, we first discuss the general properties of an
intermediate-statistics quantum bracket, $[ u,v]_{n}=uv-e^{i2\pi /(n+1)}vu$,
which corresponds to intermediate statistics in which the maximum occupation
number of one quantum state is an arbitrary integer, $n$. A further study of
the operator realization of intermediate statistics is given. We construct the
intermediate-statistics coherent state. An intermediate-statistics oscillator
is constructed, which returns to bosonic and fermionic oscillators respectively
when $n\to \infty $ and $n=1$. The energy spectrum of such an
intermediate-statistics oscillator is calculated. Finally, we discuss the
intermediate-statistics representation of angular momentum ($su(2)$) algebra.
Moreover, a further study of the operator realization of intermediate
statistics is given in the Appendix.


title: The nearby QSO host I Zw 1: The stellar disk and adjacent objects

abstract:
  The relation between tidal interactions, starbursts, and the onset and/or
fueling of active galactic nuclei (AGN) is a matter of debate. I Zw 1 is
considered as the prototypical narrow-line Seyfert 1 galaxy (NLS1) and as one
of the closest quasi-stellar objects (QSOs). With a clear spiral host and a
small companion galaxy to the west, I Zw 1 is a possible example of
minor-merger-related nuclear activity. This study investigates possible signs
of a relation between merger process, star formation activity, and AGN
properties in the case of I Zw 1. The morphology of I Zw 1 and nearby sources
is investigated via high-resolution NIR images. Color trends in the host galaxy
of I Zw 1 are discussed by means of optical-to-NIR color composites. Long-slit
spectra of the QSO nucleus of I Zw 1 and of the two nearby sources to the north
and the west of the I Zw 1 disk are analyzed. The data support the scenario of
a tidal interaction between I Zw 1 and the small companion galaxy to the west.
A concentration of blue color in the western part of the I Zw 1 host galaxy
might be the manifestation of merger-induced star formation activity. Previous
findings that the likely companion has an old evolved stellar population are
substantiated by the new data. An extension to the west of the putative
companion emerges as a separate source. The source to the north of the I Zw 1
disk is reconfirmed as a late-type foreground star. Lines in the nuclear K-band
spectrum of I Zw 1 are discussed in comparison to data prior to this article
and line fluxes are reported.


title:
Ab initio estimate of temperature dependence of electrical conductivity
  in a model amorphous material: hydrogenated amorphous silicon

abstract:
  We present an ab initio calculation of the DC conductivity of amorphous
silicon and hydrogenated amorphous silicon. The Kubo-Greenwood formula is used
to obtain the DC conductivity, by thermal averaging over extended dynamical
simulation. Its application to disordered solids is discussed. The conductivity
is computed for a wide range of temperatures and doping is explored in a naive
way by shifting the Fermi level. We observed the Meyer-Neldel rule for the
electrical conductivity with E_MNR = 0.06 eV and a temperature coefficient of
resistance, TCR ~ -2.0% K^-1 for a-Si:H. In general, experimental trends are
reproduced by these calculations, and this suggests the possible utility of the
approach for modeling carrier transport in other disordered systems.


title: Ensemble inequivalence in random graphs

abstract:
  We present a complete analytical solution of a system of Potts spins on a
random k-regular graph in both the canonical and microcanonical ensembles,
using the Large Deviation Cavity Method (LDCM). The solution is shown to be
composed of three different branches, resulting in an non-concave entropy
function.The analytical solution is confirmed with numerical Metropolis and
Creutz simulations and our results clearly demonstrate the presence of a region
with negative specific heat and, consequently, ensemble inequivalence between
the canonical and microcanonical ensembles.


title:
A large acceptance scintillator detector with wavelength shifting fibre
  read-out for search of eta-nucleus bound states

abstract:
  A large acceptance scintillator detector with wavelength shifting optical
fibre readout has been designed and built to detect the decay particles of
$\eta$-nucleus bound system (the so-called $\eta$-mesic nuclei), namely,
protons and pions. The detector, named as ENSTAR detector, consists of 122
pieces of plastic scintillator of various shapes and sizes, which are arranged
in a cylindrical geometry to provide particle identification, energy loss and
coarse position information for these particles. A solid angle coverage of
$\sim$95% of total 4$\pi$ is obtained in the present design of the detector.
Monte Carlo phase space calculations performed to simulate the formation and
decay of $\eta$-mesic nuclei suggest that its decay particles, the protons and
pions are emitted with an opening angle of 150$^\circ \pm 20^\circ$, and with
energies in the range of 25 to 300 MeV and 225 to 450 MeV respectively. The
detailed GEANT simulations show that $\sim$ 80 % of the decay particles
(protons and pions) can be detected within ENSTAR. Several test measurements
using alpha source, cosmic-ray muons etc. have been carried out to study the
response of ENSTAR scintillator pieces. The in-beam tests of fully assembled
detector with proton beam of momentum 870 MeV/c from the Cooler synchrotron
COSY have been performed. The test results show that the scintillator fiber
design chosen for the detector has performed satisfactorily well. The present
article describes the detector design, simulation studies, construction details
and test results.


title:
Nucleon-induced fission cross-sections of tantalum and separated
  tungsten isotopes and "compound nucleus" effect in intermediate energy region

abstract:
  Neutron- and proton-induced fission cross-sections of separated isotopes of
tungsten (182W, 183W, 184W, and 186W) and 181Ta relative to 209Bi have been
measured in the incident nucleon energy region 50 - 200 MeV using fission
chambers based on thin-film breakdown counters (TFBC) using quasi-monoenergetic
neutrons from the 7Li(p,n) reaction and at the proton beams of The Svedberg
Laboratory (TSL), Uppsala University (Uppsala, Sweden). The results are
compared with predictions by the CEM03.01 event generator, as well as with the
recent data for nuclei in the lead-bismuth region. The effect of "compound
nucleus" in the intermediate energy region is discussed, displaying in
exponential dependence of nucleon-induced fission cross-sections on the
parameter Z^2/A of the composite system (projectile+target nucleus), and in
other characteristics of the fission process for which parameter Z^2/A plays a
role similar to the one of the usual liquid-drop parameter Z^2/A of compound
nuclei.


title: The loop-quantum-gravity vertex-amplitude

abstract:
  Spinfoam theories are hoped to provide the dynamics of non-perturbative loop
quantum gravity. But a number of their features remain elusive. The best
studied one -the euclidean Barrett-Crane model- does not have the boundary
state space needed for this, and there are recent indications that,
consequently, it may fail to yield the correct low-energy $n$-point functions.
These difficulties can be traced to the SO(4) -> SU(2) gauge fixing and the way
certain second class constraints are imposed, arguably incorrectly, strongly.
We present an alternative model, that can be derived as a bona fide
quantization of a Regge discretization of euclidean general relativity, and
where the constraints are imposed weakly. Its state space is a natural subspace
of the SO(4) spin-network space and matches the SO(3) hamiltonian spin network
space. The model provides a long sought SO(4)-covariant vertex amplitude for
loop quantum gravity.


title: Pulsation and orbit of AU Pegasi

abstract:
  AU Pegasi is a pulsating star in a spectroscopic binary system with an
orbital period of 53.26 days. Between 1960 and 1990 an extremely rapid period
increase was observed in the value of the pulsation period, but in the last 15
years the observation show that the period set in 2.411 days. Fourier analysis
of photometric data obtained during the ASAS project and those taken at the
Piszkesteto Mountain Station of the Konkoly Observatory during 1994-2005
indicate that AU Pegasi is pulsating in two modes simultaneously, and the ratio
of the frequencies of the two modes is 0.706, a value common for double-mode
classical Cepheids. A careful analysis of other photometric observations
obtained during the era of the strong period increase also revealed existence
of a second mode. This may suggest that this star is not a Type II Cepheid,
despite its galactic position.


title:
Generalised Einstein condition and cone construction for parabolic
  geometries

abstract:
  This paper attempts to define a generalisation of the standard Einstein
condition (in conformal/metric geometry) to any parabolic geometry. To do so,
it shows that any preserved involution $\sigma$ of the adjoint bundle $\mc{A}$
gives rise, given certain algebraic conditions, to a unique preferred affine
connection $\nabla$ with covariantly constant rho-tensor $\mathsf{P}$,
compatible with the algebraic bracket on $\mc{A}$. These conditions can
reasonably be considered the generalisations of the Einstein condition, and
recreate the standard Einstein condition in conformal geometry. The existence
of such an involution is implies by some simpler structures: preserved metrics
when the overall algebra $\mf{g}$ is $\mf{sl}(m,\mbb{F})$, preserved complex
structures anti-commuting with the skew-form for $\mf{g}=\mf{sp}(2m,\mbb{F})$,
and preserved subundles of the tangent bundle, of a certain rank, for all the
other non-exceptional simple Lie algebras. Examples of Einstein involutions are
constructed or referenced for several geometries. The existence of cone
constructions for certain Einstein involutions is then demonstrated.


title: Torsion units in integral group ring of Higman-Sims simple group

abstract:
  Using the Luthar-Passi method, we investigate the classical Zassenhaus
conjecture for the normalized unit group of the integral group ring of the
Higman-Sims simple sporadic group HS. As a consequence, we confirm the
Kimmerle's conjecture on prime graphs for this sporadic group.


title: Electro-optically tunable microring resonators in lithium niobate

abstract:
  Optical microresonators have recently attracted a growing attention in the
photonics community. Their applications range from quantum electro-dynamics to
sensors and filtering devices for optical telecommunication systems, where they
are likely to become an essential building block. The integration of nonlinear
and electro-optical properties in the resonators represents a very stimulating
challenge, as it would incorporate new and more advanced functionality. Lithium
niobate is an excellent candidate material, being an established choice for
electro-optic and nonlinear optical applications. Here we report on the first
realization of optical microring resonators in submicrometric thin films of
lithium niobate. The high index contrast films are produced by an improved
crystal ion slicing and bonding technique using benzocyclobutene. The rings
have radius R=100 um and their transmission spectrum has been tuned using the
electro-optic effect. These results open new perspectives for the use of
lithium niobate in chip-scale integrated optical devices and nonlinear optical
microcavities.


title: Observing the evolution of a quantum system that does not evolve

abstract:
  This article deals with the problem of gathering information on the time
evolution of a single metastable quantum system whose evolution is impeded by
the quantum Zeno effect. It has been found it is in principle possible to
obtain some information on the time evolution and, depending on the specific
system, even to measure its average decay rate, even if the system does not
undergo any evolution at all.


title:
Invariants of triangular Lie algebras with one nilindependent diagonal
  element

abstract:
  The invariants of solvable triangular Lie algebras with one nilindependent
diagonal element are studied exhaustively. Bases of the invariant sets of all
such algebras are constructed using an original algebraic algorithm based on
Cartan's method of moving frames and the special technique developed for
triangular and related algebras in [J. Phys. A: Math. Theor. 40 (2007),
7557-7572]. The conjecture of Tremblay and Winternitz [J. Phys. A: Math. Gen.
34 (2001), 9085-9099] on the number and form of elements in the bases is
completed and proved.


title:
Faddeev-Jackiw Quantization of the Gauge Invariant Self-dual Fields
  Relative to String Theory

abstract:
  We obtain a new symplectic Lagrangian density and deduce Faddeev-Jackiw (FJ)
generalized brackets of the gauge invariant self-dual fields interacting with
gauge fields. We further give FJ quantization of this system. Furthermore, the
FJ method is compared with Dirac method, the results show the two methods are
equivalent in the quantization of this system. And by the practical research in
this letter, it can be found that the FJ method is really simpler than the
Dirac method, namely, the FJ method obviates the need to distinguish primary
and secondary constraints and first- and second-class constraints. Therefore,
the FJ method is a more economical and effective method of quantization.


title:
Nonlinear generalized functions and the Heisenberg-Pauli foundations of
  Quantum Field Theory

abstract:
  In 1929 Heisenberg and Pauli laid the foundations of QFT by quantizing the
fields (method of canonical quantization). This general theory of quantized
fields has remained undisputed up to now. We show how the unmodified
Heisenberg-Pauli calculations make sense mathematically by using a theory of
generalized functions adapted to nonlinear operations. By providing an
appropriate mathematical setting, nonlinear generalized functions open doors
for their understanding but there remains presumably very hard technical
problems. (i) Domains of the interacting field operators: a priori the H-P
calculations give time dependent dense domains, what is not very convenient;
(ii) Calculations of the resulting matrix elements of the S operator: from the
unitarity of the S operator as a whole there are no longer ``infinities,'' but
a priori there is no other hope than heavy computer calculations; (iii)
Connection with renormalization theory: it should provide an approximation when
the coupling constant is small. The aim of this paper is to present, on the
grounds of a standard mathematical model of QFT (a self interacting scalar
boson field), a basis for improvement without significant prerequisites in
mathematics and physics. It is an attempt to use nonlinear generalized
functions in QFT, starting directly from the calculations made by physicists,
in the same way as they have already been used in classical mechanics and
general relativity.


title:
The Reduced Genus-One Gromov-Witten Invariants of Calabi-Yau
  Hypersurfaces

abstract:
  We compute the reduced genus 1 Gromov-Witten invariants of Calabi-Yau
hypersurfaces. As a consequence, we confirm the 1993 Bershadsky-Cecotti
Ooguri-Vafa (BCOV) prediction for the standard genus 1 GW-invariants of a
quintic threefold. We combine constructions from a series of previous papers
with the classical localization theorem to relate the reduced genus 1
invariants of a CY-hypersurface to previously computed integrals on moduli
spaces of stable genus 0 maps into projective space. The resulting, rather
unwieldy, expressions for a genus 1 equivariant generating function simplify
drastically, using a regularity property of a genus 0 equivariant generating
function in half of the cases. Finally, by disregarding terms that cannot
effect the non-equivariant part of the former, we relate the answer to an
explicit hypergeometric series in a simple way. The approach described in this
paper is systematic. It is directly applicable to computing reduced genus 1
GW-invariants of other complete intersections and should apply to higher-genus
localization computations.


title: Light-shift-induced photonic nonlinearities

abstract:
  We propose a new method to produce self- and cross-Kerr photonic
nonlinearities, using light-induced Stark shifts due to the interaction of a
cavity mode with atoms. The proposed experimental set-up is considerably
simpler than in previous approaches, while the strength of the nonlinearity
obtained with a single atom is the same as in the setting based on
electromagnetically induced transparency. Furthermore our scheme can be applied
to engineer effective photonic nonlinear interactions whose strength increases
with the number of atoms coupled to the cavity mode, leading to photon-photon
interactions several orders of magnitude larger than previously considered
possible.


title: Gluonic phases and phase diagram in neutral two flavor dense QCD

abstract:
  A numerical analysis of several phases in the cold neutral two flavor dense
quark matter is realized. In the analysis, besides the normal, single plane
wave LOFF, and color superconducting 2SC/g2SC phases, we also include two
gluonic phases (the gluonic cylindrical phase II and the gluonic color-spin
locked one). It is shown that these two gluonic phases are dynamically realized
and, on the basis of this analysis, the phase diagram with respect to the
coupling strength in this medium is suggested. In particular, it is shown that
the gluonic phases are energetically favorable in a wide region of the
parameter space. On the other hand, there also exists a window where the LOFF
phase is stable. The 2SC state and the normal one are realized in the strong
and weak coupling regimes, respectively, as was expected.


title:
Photon-induced Nucleosynthesis: Current Problems and Experimental
  Approaches

abstract:
  Photon-induced reactions play a key role in the nucleosynthesis of rare
neutron-deficient p-nuclei. The paper focuses on (gamma,alpha), (gamma,p), and
(gamma,n) reactions which define the corresponding p-process path. The relation
between stellar reaction rates and laboratory cross sections is analyzed for
photon-induced reactions and their inverse capture reactions to evaluate
various experimental approaches. An improved version S_C(E) of the
astrophysical S-factor is suggested which is based on the Coulomb wave
functions. S_C(E) avoids the apparent energy dependence which is otherwise
obtained for capture reactions on heavy nuclei. It is found that a special type
of synchrotron radiation available at SPring-8 that mimics stellar blackbody
radiation at billions of Kelvin is a promising tool for future experiments. By
using the blackbody synchrotron radiation, sufficient event rates for
(gamma,alpha) and (gamma,p) reactions in the p-process path can be expected.
These experiments will provide data to improve the nuclear parameters involved
in the statistical model and thus reduce the uncertainties of nucleosynthesis
calculations.


title: Pulsed beams as field probes for precision measurement

abstract:
  We describe a technique for mapping the spatial variation of static electric,
static magnetic, and rf magnetic fields using a pulsed atomic or molecular
beam. The method is demonstrated using a beam designed to measure the electric
dipole moment of the electron. We present maps of the interaction region,
showing sensitivity to (i) electric field variation of 1.5 V/cm at 3.3 kV/cm
with a spatial resolution of 15 mm; (ii) magnetic field variation of 5 nT with
25 mm resolution; (iii) radio-frequency magnetic field amplitude with 15 mm
resolution. This new diagnostic technique is very powerful in the context of
high-precision atomic and molecular physics experiments, where pulsed beams
have not hitherto found widespread application.


title:
Beyond Collins and Sivers: further measurements of the target transverse
  spin-dependent azimuthal asymmetries in semi-inclusive DIS from COMPASS

abstract:
  In semi-inclusive DIS of polarized leptons on a transversely polarized target
eight azimuthal modulations appear in the cross-section. Within QCD parton
model four azimuthal asymmetries can be interpreted at leading order, two of
them being the already measured Collins and Sivers asymmetries. The other two
leading twist asymmetries, related to different transverse momentum dependent
quark distribution functions, and also additional four asymmetries which can be
interpreted as twist-three contributions have been measured for the first time
at COMPASS, using a 160 GeV/c longitudinally polarized ($P_{beam}\simeq -0.8$)
muon beam and a transversely polarized $^6LiD$ target. We present here the
preliminary results from the 2002-2004 data.


title:
Chromomagnetic Instability and Induced Magnetic Field in Neutral
  Two-Flavor Color Superconductivity

abstract:
  We find that the chromomagnetic instability existing in neutral two- flavor
color superconductivity at moderate densities is removed by the formation of an
inhomogeneous condensate of charged gluons and the corresponding induction of a
magnetic field. It is shown that this inhomogeneous ground state is
energetically favored over a homogeneous one. The spontaneous induction of a
magnetic field in a color superconductor at moderate densities can be of
interest for the astrophysics of compact stellar objects exhibiting strong
magnetic fields as magnetars.


title: Misere quotients for impartial games: Supplementary material

abstract:
  We provide supplementary appendices to the paper Misere quotients for
impartial games. These include detailed solutions to many of the octal games
discussed in the paper, and descriptions of the algorithms used to compute most
of our solutions.


title: Qubit-portraits of qudit states and quantum correlations

abstract:
  The machinery of qubit-portraits of qudit states, recently presented, is
consider here in more details in order to characterize the presence of quantum
correlations in bipartite qudit states. In the tomographic representation of
quantum mechanics, Bell-like inequalities are interpreted as peculiar
properties of a family of classical joint probability distributions which
describe the quantum state of two qudits. By means of the qubit-portraits
machinery a semigroup of stochastic matrices can be associated to a given
quantum state. The violation of the CHSH inequalities is discussed in this
framework with some examples, we found that quantum correlations in qutrit
isotropic states can be detected by the suggested method while it cannot in the
case of qutrit Werner states.


title: Decaying warm dark matter and neutrino masses

abstract:
  Neutrino masses may arise from spontaneous breaking of ungauged lepton
number. Due to quantum gravity effects the associated Goldstone boson - the
majoron - will pick up a mass. We determine the lifetime and mass required by
cosmic microwave background observations so that the massive majoron provides
the observed dark matter of the Universe. The majoron DDM scenario fits nicely
in models where neutrino masses arise a la seesaw, and may lead to other
possible cosmological implications.


title: Nonuniform Thickness and Weighted Distance

abstract:
  Nonuniform tubular neighborhoods of curves in Euclidean n-space are studied
by using weighted distance functions and generalizing the normal exponential
map. Different notions of injectivity radii are introduced to investigate
singular but injective exponential maps. A generalization of the thickness
formula is obtained for nonuniform thickness. All singularities within almost
injectivity radius are classified by the Horizontal Collapsing Property.
Examples are provided to show the distinction between the different types of
injectivity radii, as well as showing that the standard differentiable
injectivity radius fails to be upper semicontinuous on a singular set of weight
functions.


title: Exploded Fibrations

abstract:
  Initiated by Gromov, the study of holomorphic curves in symplectic manifolds
has been a powerfull tool in symplectic topology, however the moduli space of
holomorphic curves is often very difficult to find. A common technique is to
study the limiting behavior of holomorphic curves in a degenerating family of
complex structures which corresponds to a kind of adiabatic limit. The category
of exploded fibrations is an extension of the smooth category in which some of
these degenerations can be described as smooth families.
  The first part of this paper is devoted to defining exploded fibrations and a
slightly more specialized category of exploded torus fibrations. Later sections
contain the transverse interesction theory for exploded fibrations and some
examples of holomorphic curves in exploded torus fibrations, including a brief
discussion of the relationship between tropical geometry and exploded torus
fibrations. In the final section, the perturbation theory of holomorphic curves
in exploded torus fibrations is sketched.


title: Charge Density of the Neutron

abstract:
  A model-independent analysis of the infinite-momentum-frame charge density of
partons in the transverse plane is presented for the nucleon. We find that the
neutron parton charge density is negative at the center, so that the square of
the transverse charge radius is positive, in contrast with many expectations.
Additionally, the proton's central u quark charge density is larger than that
of the d quark by about 70 %. The proton (neutron) charge density has a long
range positively (negatively) charged component.


title: A New Class of Rank Breaking Orbifolds

abstract:
  We describe field-theory T^2/Z_n orbifolds that offer new ways of breaking
SU(N) to lower rank subgroups. We introduce a novel way of embedding the point
group into the gauge group, beyond the usual mapping of torus and root
lattices. For this mechanism to work the torus Wilson lines must carry
nontrivial 't Hooft flux. The rank lowering mechanism proceeds by inner
automorphisms but is not related to continous Wilson lines and does not give
rise to any associated moduli. We give a complete classification of all
possible SU(N) breaking patterns. We also show that the case of general gauge
group can already be understood entirely in terms of the SU(N) case and the
knowledge of standard orbifold constructions with vanishing 't Hooft flux.


title: Equations of motion, initial and boundary conditions for GRB

abstract:
  We compare and contrast the different approaches to the optically thick
adiabatic phase of GRB all the way to the transparency. Special attention is
given to the role of the rate equation to be self consistently solved with the
relativistic hydrodynamic equations. The works of Shemi and Piran (1990),
Piran, Shemi and Narayan (1993), Meszaros, Laguna and Rees (1993) and Ruffini,
Salmonson, Wilson and Xue (1999,2000) are compared and contrasted. The role of
the baryonic loading in these three treatments is pointed out. Constraints on
initial conditions for the fireball produced by electro-magnetic black hole are
obtained.


title: The Nahm transform for calorons

abstract:
  In this paper, we complete the proof of an equivalence given by Nye and
Singer of the equivalence between calorons (instantons on $S^1\times R^3$) and
solutions to Nahm's equations over the circle, both satisfying appropriate
boundary conditions. Many of the key ingredients are provided by a third way of
encoding the same data which involves twistors and complex geometry.


title: Accurate backgrounds to Higgs production at the LHC

abstract:
  Corrections of 10-30% for backgrounds to the H --> WW --> l^+l^-\sla{p}_T
search in vector boson and gluon fusion at the LHC are reviewed to make the
case for precise and accurate theoretical background predictions.


title:
Spitzer and ground-based infrared observations of the 2006 eruption of
  RS Ophiuchi

abstract:
  We present Spitzer Space Telescope and complementary ground-based infrared
observations of the recurrent nova RS Ophiuchi, obtained over the period 64-111
days after the 2006 eruption. The Spitzer IRS data show a rich emission line
spectrum superimposed on a free-free continuum. The presence of fine structure
and coronal infrared lines lead us to deduce that there are at least two
temperatures (1.5e5K and 9e5K) in the ejecta/wind environment, and that the
electron density in the `cooler' region is 2.2e5 cm-3. The determination of
elemental abundances is not straightforward but on the assumption that the Ne
and O fine structure lines arise in the same volume of the ejecta, the O/Ne
ratio is >~0.6 by number.


title: GRB970228 as a prototype for short GRBs with afterglow

abstract:
  GRB970228 is analyzed as a prototype to understand the relative role of short
GRBs and their associated afterglows, recently observed by Swift and HETE-II.
Detailed theoretical computation of the GRB970228 light curves in selected
energy bands are presented and compared with observational BeppoSAX data.


title:
A note on the diffusivity of finite-range asymmetric exclusion processes
  on Z

abstract:
  The diffusivity $D(t)$ of finite-range asymmetric exclusion processes on
$\mathbb Z$ with non-zero drift is expected to be of order $t^{1/3}$.
Sepp\"{a}l\"ainen and Bal\'azs recently proved this conjecture for the nearest
neighbor case. We extend their results to general finite range exclusion by
proving that the Laplace transform of the diffusivity is of the conjectured
order. We also obtain a pointwise upper bound for $D(t)$ the correct order.


title: Theoretical interpretation of GRB 011121

abstract:
  GRB011121 is analyzed as a prototype to understand the ``flares'' recently
observed by Swift in the afterglow of many GRB sources. Detailed theoretical
computation of the GRB011121 light curves in selected energy bands are
presented and compared and contrasted with observational BeppoSAX data.


title: The phonon dispersion of graphite by inelastic x-ray scattering

abstract:
  We present the full in-plane phonon dispersion of graphite obtained from
inelastic x-ray scattering, including the optical and acoustic branches, as
well as the mid-frequency range between the $K$ and $M$ points in the Brillouin
zone, where experimental data have been unavailable so far. The existence of a
Kohn anomaly at the $K$ point is further supported. We fit a fifth-nearest
neighbour force-constants model to the experimental data, making improved
force-constants calculations of the phonon dispersion in both graphite and
carbon nanotubes available.


title:
Charge and spin density response functions of the clean two-dimensional
  electron gas with Rashba spin-orbit coupling at finite momenta and
  frequencies

abstract:
  We analytically evaluate charge and spin density response functions of the
clean two-dimensional electron gas with Rashba spin-orbit coupling at finite
momenta and frequencies. On the basis of our exact expressions we discuss the
accuracy of the long-wavelength and the quasiclassical approximations. We also
derive the static limit of spin susceptibilities and demonstrate, in
particular, how the Kohn-like anomalies in their derivatives are related to the
spin-orbit modification of the Ruderman-Kittel-Kasuya-Yosida interaction.
Taking into account screening and exchange effects of the Coulomb interaction,
we describe the collective charge and spin density excitation modes which
appear to be coupled due to nonvanishing spin-charge response function.


title:
Bimodal Counting Statistics in Single Electron Tunneling through a
  Quantum Dot

abstract:
  We explore the full counting statistics of single electron tunneling through
a quantum dot using a quantum point contact as non-invasive high bandwidth
charge detector. The distribution of counted tunneling events is measured as a
function of gate and source-drain-voltage for several consecutive electron
numbers on the quantum dot. For certain configurations we observe
super-Poissonian statistics for bias voltages at which excited states become
accessible. The associated counting distributions interestingly show a bimodal
characteristic. Analyzing the time dependence of the number of electron counts
we relate this to a slow switching between different electron configurations on
the quantum dot.


title:
Generalized Morse and Poschl-Teller potentials : The connection via
  Schrodinger equation

abstract:
  We present here a systematic and unified treatment to connect the Schrodinger
equation corresponding to generalized Morse and Poschl-Teller potentials. We
then show that the wave functions and generalized potentials are linked through
the Fourier and Hankel transforms, respectively.


title: The asymptotic volume of the Birkhoff polytope

abstract:
  Let m,n be positive integers. Define T(m,n) to be the transportation polytope
consisting of the m x n non-negative real matrices whose rows each sum to 1 and
whose columns each sum to m/n. The special case B(n)=T(n,n) is the much-studied
Birkhoff-von Neumann polytope of doubly-stochastic matrices. Using a recent
asymptotic enumeration of non-negative integer matrices (Canfield and McKay,
2007), we determine the asymptotic volume of T(m,n) as n goes to infinity, with
m=m(n) such that m/n neither decreases nor increases too quickly. In
particular, we give an asymptotic formula for the volume of B(n).


title: A VLBI polarization study of SiO masers towards VY CMa

abstract:
  Maser emission from the SiO molecule has been widely observed in the
near-circumstellar envelopes of late-type, evolved stars. VLBI images can
resolve individual SiO maser spots, providing information about the kinematics
and magnetic field in the extended atmospheres of these stars. This poster
presents full polarization images of several SiO maser lines towards the
supergiant star VY CMa. VY CMa is a particularly strong SiO maser source and
allows observations of a wide range of maser transitions. We discuss
implications of these observations for VY CMa morphology, polarization, and
pumping models.


title: Spin-Hall edge spin polarization in a ballistic 2D electron system

abstract:
  Universal properties of spin-Hall effect in ballistic 2D electron systems are
addressed. The net spin polarization across the edge of the conductor is second
order, ~\lambda^2, in spin-orbit coupling constant independent of the form of
the boundary potential, with the contributions of normal and evanescent modes
each being ~ \sqrt{\lambda} but of opposite signs. This general result is
confirmed by the analytical solution for a hard-wall boundary, which also
yields the detailed distribution of the local spin polarization. The latter
shows fast (Friedel) oscillations with the spin-orbit coupling entering via the
period of slow beatings only. Long-wavelength contributions of evanescent and
normal modes exactly cancel each other in the spectral distribution of the
local spin density.


title: Singlet Higgs Phenomenology and the Electroweak Phase Transition

abstract:
  We study the phenomenology of gauge singlet extensions of the Standard Model
scalar sector and their implications for the electroweak phase transition. We
determine the conditions on the scalar potential parameters that lead to a
strong first order phase transition as needed to produce the observed baryon
asymmetry of the universe. We analyze the constraints on the potential
parameters derived from Higgs boson searches at LEP and electroweak precision
observables. For models that satisfy these constraints and that produce a
strong first order phase transition, we discuss the prospective signatures in
future Higgs studies at the Large Hadron Collider and a Linear Collider. We
argue that such studies will provide powerful probes of phase transition
dynamics in models with an extended scalar sector.


title:
Vortex Lattice Locking in Rotating Two-Component Bose-Einstein
  Condensates

abstract:
  The vortex density of a rotating superfluid, divided by its particle mass,
dictates the superfluid's angular velocity through the Feynman relation. To
find how the Feynman relation applies to superfluid mixtures, we investigate a
rotating two-component Bose-Einstein condensate, composed of bosons with
different masses. We find that in the case of sufficiently strong interspecies
attraction, the vortex lattices of the two condensates lock and rotate at the
drive frequency, while the superfluids themselves rotate at two different
velocities, whose ratio is the ratio between the particle mass of the two
species. In this paper, we characterize the vortex-locked state, establish its
regime of stability, and find that it surives within a disk smaller than a
critical radius, beyond which vortices become unbound, and the two Bose-gas
rings rotate together at the frequency of the external drive.

categories: cond-mat.str-el cond-mat.mes-hall nlin.PS physics.atom-ph


title: A modularity test for elliptic mirror symmetry

abstract:
  In this note a prediction of an algebraic mirror construction is checked for
elliptic curves of Brieskorn-Pham type via number theoretic methods. It is
shown that the modular forms associated to the Hasse-Weil L-series of mirror
pairs of such curves are identical.


title:
Micropatterned Electrostatic Traps for Indirect Excitons in Coupled GaAs
  Quantum Wells

abstract:
  We demonstrate an electrostatic trap for indirect excitons in a field-effect
structure based on coupled GaAs quantum wells. Within the plane of a double
quantum well indirect excitons are trapped at the perimeter of a SiO2 area
sandwiched between the surface of the GaAs heterostructure and a
semitransparent metallic top gate. The trapping mechanism is well explained by
a combination of the quantum confined Stark effect and local field enhancement.
We find the one-dimensional trapping potentials in the quantum well plane to be
nearly harmonic with high spring constants exceeding 10 keV/cm^2.


title: Single spike solutions for strings on S2 and S3

abstract:
  We study solutions for rigidly rotating strings on a two sphere. Among them
we find two limiting cases that have a particular interest, one is the already
known giant magnon and the other we call the single spike solution. The
limiting behavior of this last solution is a string infinitely wrapped around
the equator. It differs from that solution by the existence of a single spike
of height theta that points toward the north pole.
  We study its properties and compute its energy E and angular momentum J as a
function of theta. We further generalize the solution by adding one angular
momentum to obtain a solution on S3. We find a spin chain interpretations of
these results in terms of free fermions and the Hubbard model but the exact
relation with the same models derived from the field theory is not clear.


title: Poincare recurrences of Schwarzschild black holes

abstract:
  We discuss massive scalar perturbations of a Schwarzschild black hole. We
argue that quantum effects alter the effective potential near the horizon
resulting in Poincare recurrences in Green functions. Results at the
semi-classical level are independent of the details of the modification of the
potential provided its minimum near the horizon is inversely proportional to
the square of the Poincare time. This modification may be viewed as a change in
the near-horizon geometry. We consider explicitly the examples of a brick wall,
a smooth cutoff and a wormhole-like modification showing that they all lead to
the same results at leading order.


title: Higher-order Threshold Corrections for Single Top Quark Production

abstract:
  I discuss single top quark production at the Tevatron and the LHC. The cross
section, including soft-gluon threshold corrections through NNNLO, is presented
for each partonic channel. The higher-order corrections provide significant
contributions to the single top cross sections at both colliders.


title: Charm and charmonium spectroscopy at B-factories

abstract:
  We report on most recent Charm and Charmonium spectroscopy results from the
B-factories


title:
Charged particles in crossed and longitudinal electromagnetic fields and
  beam guides

abstract:
  We consider a class of electromagnetic fields that contains crossed fields
combined with longitudinal electric and magnetic fields. We study the motion of
a classical particle (solutions of the Lorentz equations) in such fields. Then,
we present an analysis that allows one to decide which fields from the class
act as a beam guide for charged particles, and we find some time-independent
and time-dependent configurations with beam guiding properties. We demonstrate
that the Klein-Gordon and Dirac equations with all the fields from the class
can be solved exactly. We study these solutions, which were not known before,
and prove that they form complete and orthogonal sets of functions.


title:
Modeling Heterogeneous Materials via Two-Point Correlation Functions: I.
  Basic Principles

abstract:
  Heterogeneous materials abound in nature and man-made situations. Examples
include porous media, biological materials, and composite materials. Diverse
and interesting properties exhibited by these materials result from their
complex microstructures, which also make it difficult to model the materials.
In this first part of a series of two papers, we collect the known necessary
conditions on the standard two-point correlation function S2(r) and formulate a
new conjecture. In particular, we argue that given a complete two-point
correlation function space, S2(r) of any statistically homogeneous material can
be expressed through a map on a selected set of bases of the function space. We
provide new examples of realizable two-point correlation functions and suggest
a set of analytical basis functions. Moreover, we devise an efficient and
isotropy- preserving construction algorithm, namely, the Lattice-Point
algorithm to generate realizations of materials from their two- point
correlation functions based on the Yeong-Torquato technique. Subsequent
analysis can be performed on the generated images to obtain desired macroscopic
properties. These developments are integrated here into a general scheme that
enables one to model and categorize heterogeneous materials via two-point
correlation functions.


title:
Reduced Complexity Sphere Decoding for Square QAM via a New Lattice
  Representation

abstract:
  Sphere decoding (SD) is a low complexity maximum likelihood (ML) detection
algorithm, which has been adapted for different linear channels in digital
communications. The complexity of the SD has been shown to be exponential in
some cases, and polynomial in others and under certain assumptions. The sphere
radius and the number of nodes visited throughout the tree traversal search are
the decisive factors for the complexity of the algorithm. The radius problem
has been addressed and treated widely in the literature. In this paper, we
propose a new structure for SD, which drastically reduces the overall
complexity. The complexity is measured in terms of the floating point
operations per second (FLOPS) and the number of nodes visited throughout the
algorithm tree search. This reduction in the complexity is due to the ability
of decoding the real and imaginary parts of each jointly detected symbol
independently of each other, making use of the new lattice representation. We
further show by simulations that the new approach achieves 80% reduction in the
overall complexity compared to the conventional SD for a 2x2 system, and almost
50% reduction for the 4x4 and 6x6 cases, thus relaxing the requirements for
hardware implementation.


title: Standard Bases in K[[t_1,...,t_m]][x_1,...,x_n]^s

abstract:
  In this paper we study standard bases for submodules of
K[[t_1,...,t_m]][x_1,...,x_n]^s respectively of their localisation with respect
to a t-local monomial ordering. The main step is to prove the existence of a
division with remainder generalising and combining the division theorems of
Grauert and Mora. Everything else then translates naturally. Setting either m=0
or n=0 we get standard bases for polynomial rings respectively for power series
rings as a special case. We then apply this technique to show that the
t-initial ideal of an ideal over the Puiseux series field can be read of from a
standard basis of its generators. This is an important step in the constructive
proof that each point in the tropical variety of such an ideal admits a
lifting.


title:
A theorem about relative entropy of quantum states with an application
  to privacy in quantum communication

abstract:
  We prove the following theorem about relative entropy of quantum states.
"Substate theorem: Let rho and sigma be quantum states in the same Hilbert
space with relative entropy S(rho|sigma) = Tr rho (log rho - log sigma) = c.
Then for all epsilon > 0, there is a state rho' such that the trace distance
||rho' - rho||_t = Tr sqrt{(rho' - rho)^2} <= epsilon, and
rho'/2^{O(c/epsilon^2)} <= sigma."
  It states that if the relative entropy of rho and sigma is small, then there
is a state rho' close to rho, i.e. with small trace distance ||rho' - rho||_t,
that when scaled down by a factor 2^{O(c)} `sits inside', or becomes a
`substate' of, sigma. This result has several applications in quantum
communication complexity and cryptography. Using the substate theorem, we
derive a privacy trade-off for the set membership problem in the two-party
quantum communication model. Here Alice is given a subset A of [n], Bob an
input i in [n], and they need to determine if i in A.
  "Privacy trade-off for set membership: In any two-party quantum communication
protocol for the set membership problem, if Bob reveals only k bits of
information about his input, then Alice must reveal at least n/2^{O(k)} bits of
information about her input."
  We also discuss relationships between various information theoretic
quantities that arise naturally in the context of the substate theorem.


title:
The SWIRE-VVDS-CFHTLS surveys: stellar mass assembly over the last 10
  Gyears. Evidence for a major build up of the red sequence between z=2 and z=1

abstract:
  (abridged abstract) We present an analysis of the stellar mass growth over
the last 10 Gyrs using a large 3.6$\mu$ selected sample. We split our sample
into active (blue) and quiescent (red) galaxies. Our measurements of the K-LFs
and LD evolution support the idea that a large fraction of galaxies is already
assembled at $z\sim 1.2$. Based on the analysis of the evolution of the stellar
mass-to-light ratio (in K-band) for the spectroscopic sub-sample, we derive the
stellar mass density for the entire sample. We find that the global evolution
of the stellar mass density is well reproduced by the star formation rate
derived from UV dust corrected measurements. Over the last 8Gyrs, we observe
that the stellar mass density of the active population remains approximately
constant while it gradually increases for the quiescent population over the
same timescale. As a consequence, the growth of the stellar mass in the
quiescent population must be due to the shutoff of star formation in active
galaxies that migrate into the quiescent population. From $z=2$ to $z=1.2$, we
observe a major build-up of the quiescent population with an increase by a
factor of 10 in stellar mass, suggesting that we are observing the epoch when
an increasing fraction of galaxies are ending their star formation activity and
start to build up the red sequence.


title: A tight bound on the collection of edges in MSTs of induced subgraphs

abstract:
  Let $G=(V,E)$ be a complete $n$-vertex graph with distinct positive edge
weights. We prove that for $k\in\{1,2,...,n-1\}$, the set consisting of the
edges of all minimum spanning trees (MSTs) over induced subgraphs of $G$ with
$n-k+1$ vertices has at most $nk-\binom{k+1}{2}$ elements. This proves a
conjecture of Goemans and Vondrak \cite{GV2005}. We also show that the result
is a generalization of Mader's Theorem, which bounds the number of edges in any
edge-minimal $k$-connected graph.


title: Quantum Structure of Geometry: Loopy and fuzzy?

abstract:
  In any attempt to build a quantum theory of gravity, a central issue is to
unravel the structure of space-time at the smallest scale. Of particular
relevance is the possible definition of coordinate functions within the theory
and the study of their algebraic properties, such as non-commutativity. Here we
approach this issue from the perspective of loop quantum gravity and the
picture of quantum geometry that the formalism offers. In particular, as we
argue here, this emerging picture has two main elements: i) The nature of the
quantum geometry at Planck scale is one-dimensional, polymeric with quantized
geometrical quantities and; ii) Appropriately defined operators corresponding
to coordinates by means of intrinsic, relational, constructions become
non-commuting. This particular feature of the operators, that operationally
localize points on space, gives rise to an emerging geometry that is also, in a
precise sense, fuzzy.


title: An algorithm for lifting points in a tropical variety

abstract:
  The aim of this paper is to give a constructive proof of one of the basic
theorems of tropical geometry: given a point on a tropical variety (defined
using initial ideals), there exists a Puiseux-valued ``lift'' of this point in
the algebraic variety. This theorem is so fundamental because it justifies why
a tropical variety (defined combinatorially using initial ideals) carries
information about algebraic varieties: it is the image of an algebraic variety
over the Puiseux series under the valuation map. We have implemented the
``lifting algorithm'' using Singular and Gfan if the base field are the
rational numbers. As a byproduct we get an algorithm to compute the Puiseux
expansion of a space curve singularity in (K^{n+1},0).


title:
A study of the evolution of the accretion disk of V2051 Oph through two
  outburst cycles

abstract:
  We follow the changes in the structure of the accretion disk of the dwarf
nova V2051 Oph along two separate outbursts in order to investigate the causes
of its recurrent outbursts. We apply eclipse mapping techniques to a set of
light curves covering a normal (July 2000) and a low-amplitude (August 2002)
outburst to derive maps of the disk surface brightness distribution at
different phases along the outburst cycles. The sequence of eclipse maps of the
2000 July outburst reveal that the disk shrinks at outburst onset while an
uneclipsed component of 13 per cent of the total light develops. The derived
radial intensity distributions suggest the presence of an outward-moving
heating wave during rise and of an inward-moving cooling wave during decline.
The inferred speed of the outward-moving heating wave is ~ 1.6 km/s, while the
speed of the cooling wave is a fraction of that. A comparison of the measured
cooling wave velocity on consecutive nights indicates that the cooling wave
accelerates as it travels towards disk center, in contradiction with the
prediction of the disk instability model. From the inferred speed of the
heating wave we derive a viscosity parameter alpha_{hot} ~ 0.13, comparable to
the measured viscosity parameter in quiescence. The 2002 August outburst had
lower amplitude (\Delta B ~ 0.8 mag) and the disk at outburst maximum was
smaller than on 2000 July. For an assumed distance of 92 pc, we find that along
both outbursts the disk brightness temperatures remain below the minimum
expected according to the disk instability model. The results suggest that the
outbursts of V2051 Oph are caused by bursts of increased mass transfer from the
mass-donor star.


title: A Brane World in an Arbitrary Number of Dimensions without Z_2 Symmetry

abstract:
  We consider a brane world in an arbitrary number of dimensions without Z_2
symmetry and derive the effective Einstein equation on the brane, where its
right-hand side is given by the matter on the brane and the curvature in the
bulk. This is achieved by first deriving the junction conditions for a non-Z_2
symmetric brane and second solving the Gauss equation, which relates the mean
extrinsic curvature of the brane to the curvature in the bulk, with respect to
the mean extrinsic curvature. The latter corresponds to formulating an explicit
junction condition on the mean of the extrinsic curvature, analogue to the
Israel junction condition for the jump of the extrinsic curvature. We find that
there appears a new type of an effective anisotropic fluid on the right-hand
side of the effective Einstein equation due to the fact that there is no Z_2
symmetry. The derived equation is a basic equation for the study of
Kaluza-Klein brane worlds in which some dimensions on the brane are
compactified or for a regularization scheme for a higher codimension brane
world, where the Kaluza-Klein compactification on the brane is regarded as a
means to regularize the uncontrollable spacetime singularity caused by the
higher codimension brane.


title:
Physical properties of Tolman-Bayin solutions: some cases of static
  charged fluid spheres in general relativity

abstract:
  In this article, Einstein-Maxwell space-time has been considered in
connection to some of the astrophysical solutions as previously obtained by
Tolman (1939) and Bayin (1978). The effect of inclusion of charge into these
solutions has been investigated thoroughly and also the nature of fluid
pressure and mass density throughout the sphere have been discussed.
Mass-radius and mass-charge relations have been derived for various cases of
the charged matter distribution. Two cases are obtained where perfect fluid
with positive pressures give rise to electromagnetic mass models such that
gravitational mass is of purely electromagnetic origin.


title: Artificial helical nanomagnets

abstract:
  We demonstrate the existence of a helical state in patterned multilayer
nanomagnets. The artificial helimagnets consist of a stack of single domain
ferromagnetic disks separated by insulating nonmagnetic spacers. The spiral
state is shown to originate from the magnetostatic interaction between nearest
and next nearest neighbouring single-domain disks in the stack. Since the
magnetostatic interaction for such disks is rather strong, the helical state
should be stable at room temperature. The helimagnets were fabricated from a
[Co/Si]*3 multilayer using electron beam lithography. The helical state was
confirmed by a magnetic stray field analysis using magnetic force microscopy.


title:
Regularity criterion for 3D Navier-Stokes equations in terms of the
  direction of the velocity

abstract:
  In this short note, we give a link between the regularity of the solution $u$
to the 3D Navier-Stokes equation, and the behavior of the direction of the
velocity $u/|u|$. It is shown that the control of $\Div (u/|u|)$ in a suitable
$L_t^p(L_x^q)$ norm is enough to ensure global regularity. The result is
reminiscent of the criterion in terms of the direction of the vorticity,
introduced first by Constantin and Fefferman. But in this case the condition is
not on the vorticity, but on the velocity itself. The proof, based on very
standard methods, relies on a straightforward relation between the divergence
of the direction of the velocity and the growth of energy along streamlines.


title: Packing dimension of mean porous measures

abstract:
  We prove that the packing dimension of any mean porous Radon measure on
$\mathbb R^d$ may be estimated from above by a function which depends on mean
porosity. The upper bound tends to $d-1$ as mean porosity tends to its maximum
value. This result was stated in \cite{BS}, and in a weaker form in \cite{JJ1},
but the proofs are not correct. Quite surprisingly, it turns out that mean
porous measures are not necessarily approximable by mean porous sets. We verify
this by constructing an example of a mean porous measure $\mu$ on $\mathbb R$
such that $\mu(A)=0$ for all mean porous sets $A\subset\mathbb R$.


title:
Superluminal Radio Features in the M87 Jet and the Site of Flaring TeV
  Gamma-ray Emission

abstract:
  Superluminal motion is a common feature of radio jets in powerful gamma-ray
emitting active galactic nuclei. Conventionally, the variable emission is
assumed to originate near the central supermassive black-hole where the jet is
launched on parsec scales or smaller. Here, we report the discovery of
superluminal radio features within a distinct flaring X-ray emitting region in
the jet of the nearby radio galaxy M87 with the Very Long Baseline Array. This
shows that these two phenomenological hallmarks -- superluminal motion and
high-energy variability -- are associated, and we place this activity much
further (>=120 pc) from the ``central engine'' in M87 than previously thought
in relativistic jet sources. We argue that the recent excess very high-energy
TeV emission from M87 reported by the H.E.S.S. experiment originates from this
variable superluminal structure, thus providing crucial insight into the
production region of gamma-ray emission in more distant blazars.


title: A note on vacuum energy from the de Sitter spectrum

abstract:
  It is shown that a well-known relation between entropy of a system and its
energy spectrum being applied to the early universe determines the present
vacuum energy and the time scale on which this energy can manifest itself.
Given the present vacuum energy, the relation imposes a constraint on the
initial inflationary state.


title: Dirichlet or Potts ?

abstract:
  When modeling the distribution of a set of data by a mixture of Gaussians,
there are two possibilities: i) the classical one is using a set of parameters
which are the proportions, the means and the variances; ii) the second is to
consider the proportions as the probabilities of a discrete valued hidden
variable. In the first case a usual prior distribution for the proportions is
the Dirichlet which accounts for the fact that they have to sum up to one. In
the second case, to each data is associated a hidden variable for which we
consider two possibilities: a) assuming those variables to be i.i.d. We show
then that this scheme is equivalent to the classical mixture model with
Dirichlet prior; b) assuming a Markovian structure. Then we choose the simplest
markovian model which is the Potts distribution. As we will see this model is
more appropriate for the case where the data represents the pixels of an image
for which the hidden variables represent a segmentation of that image. The main
object of this paper is to give some details on these models and different
algorithms used for their simulation and the estimation of their parameters.
  Key Words: Mixture of Gaussians, Dirichlet, Potts, Classification,
Segmentation.


title: Cyclotomic factors of the descent set polynomial

abstract:
  We introduce the notion of the descent set polynomial as an alternative way
of encoding the sizes of descent classes of permutations. Descent set
polynomials exhibit interesting factorization patterns. We explore the question
of when particular cyclotomic factors divide these polynomials. As an instance
we deduce that the proportion of odd entries in the descent set statistics in
the symmetric group S_n only depends on the number on 1's in the binary
expansion of n. We observe similar properties for the signed descent set
statistics.