title: q-Deformation and Semidualisation in 3d Quantum Gravity

abstract:
  We explore in detail the role in euclidean 3d quantum gravity of quantum Born
reciprocity or `semidualisation'. The latter is an algebraic operation defined
using quantum group methods that interchanges position and momentum. Using this
we are able to clarify the structural relationships between the effective
non-commutative geometries that have been discussed in the context of 3d
gravity. We show that the spin model based on D(U(su_2)) for quantum gravity
without cosmological constant is the semidual of a quantum particle on a
three-sphere, while the bicrossproduct (DSR) model is the semidual of a quantum
particle on hyperbolic space. We show further how the different models are all
specific limits of q-deformed models with q=e^{-\hbar \sqrt{-\Lambda}/m_p},
where m_p is the Planck mass and \Lambda is the cosmological constant, and
argue that semidualisation interchanges m_p and l_c, where l_c is the
cosmological length scale l_c=1/\sqrt{|\Lambda|}. We investigate the physics of
semidualisation by studying representation theory. In both the spin model and
its semidual we show that irreducible representations have a physical picture
as solutions of a respectively non-commutative/curved wave equation. We
explain, moreover, that the q-deformed model, at a certain algebraic level, is
self-dual under semidualisation.


title: Group schemes of period p>2

abstract:
  For a prime number p>2, we give a direct proof of Breuil's classification of
killed by p finite flat group schemes over the valuation ring of a p-adic field
with perfect residue field. As application we prove that the Galois modules of
geometric points of such group schemes and of their characteristic p analogues
coming from Faltings's strict modules can be identified via the
Fontaine-Wintenberger field-of-norms functor.


title:
Coupling of orthogonal diffusion modes in two-dimensional nonhomogeneous
  systems

abstract:
  Collective diffusion coefficient in a two-dimensional lattice gas on a
nonhomogeneous substrate is investigated using variational approach. Particles
reside at adsorption sites with different well depths potentials and jump
randomly between them. The site blocking is the only particle--particle
interaction mechanism. It is shown that the value of the diffusion coefficient
in one lattice direction depends nontrivially on the rate and the character of
the particle jumps in all directions. When the jump rate in the direction
perpendicular to that along which the diffusion is observed increases, the
collective diffusion coefficient approaches values predicted within the mean
field approximation. Results of the Monte Carlo simulations for selected
systems are very well reproduced by our analytical results.


title:
Metal-insulator transition and giant anisotropic magnetoresistance in
  ultra thin (Ga,Mn)As

abstract:
  MBE-grown, 5 nm-thick annealed Ga0.95Mn0.05As films with Tc~90K demonstrate
transition from metallic to insulating state below To~10K, where sheet
resistances Rsh~h/e2 and both longitudinal Rxx and transverse Rxy components
become comparable. Below metal-insulator transition we found giant anisotropic
magnetoresistance (GAMR), which depends on orientation of magnetization to
crystallographic axes and manifests itself in positive magnetoresistance near
50% for Rxx at T=1.7K, H//[110] crystallographic direction and parallel to
current in contrast to smaller and negative magnetoresistance for H//
direction. We connect GAMR with anisotropic spin-orbit interaction resulting in
formation of high- and low- resistance states with different localization along
non-equivalent easy axes.


title:
Antiferromagnetic transition in EuFe$_2$As$_2$: A possible parent
  compound for superconductors

abstract:
  Ternary iron arsenide EuFe$_2$As$_2$ with ThCr$_2$Si$_2$-type structure has
been studied by magnetic susceptibility, resistivity, thermopower, Hall and
specific heat measurements. The compound undergoes two magnetic phase
transitions at about 200 K and 20 K, respectively. The former was found to be
accompanied with a slight drop in magnetic susceptibility (after subtracting
the Curie-Weiss paramagnetic contribution), a rapid decrease in resistivity, a
large jump in thermopower and a sharp peak in specific heat with decreasing
temperature, all of which point to a spin-density-wave-like antiferromagnetic
transition. The latter was proposed to be associated with an A-type
antiferromagnetic ordering of Eu$^{2+}$ moments. Comparing with the physical
properties of the iso-structural compounds BaFe$_2$As$_2$ and SrFe$_2$As$_2$,
we expect that superconductivity could be induced in EuFe$_2$As$_2$ through
appropriate doping.


title: Explicit representation of membership in polynomial ideals

abstract:
  We introduce a new division formula on projective space which provides
explicit solutions to various polynomial division problems with sharp degree
estimates. We consider simple examples as the classical Macaulay theorem as
well as a quite recent result by Hickel, related to the effective
Nullstellensatz. We also obtain a related result that generalizes Max Noether's
classical AF+BG theorem.


title:
Lemaitre-Tolman-Bondi collapse from the perspective of loop quantum
  gravity

abstract:
  Lemaitre-Tolman-Bondi models as specific spherically symmetric solutions of
general relativity simplify in their reduced form some of the mathematical
ingredients of black hole or cosmological applications. The conditions imposed
in addition to spherical symmetry turn out to take a simple form at the
kinematical level of loop quantum gravity, which allows a discussion of their
implications at the quantum level. Moreover, the spherically symmetric setting
of inhomogeneity illustrates several non-trivial properties of lattice
refinements of discrete quantum gravity. Nevertheless, the situation at the
dynamical level is quite non-trivial and thus provides insights to the anomaly
problem. At an effective level, consistent versions of the dynamics are
presented which implement the conditions together with the dynamical
constraints of gravity in an anomaly-free manner. These are then used for
analytical as well as numerical investigations of the fate of classical
singularities, including non-spacelike ones, as they generically develop in
these models. None of the corrections used here resolve those singularities by
regular effective geometries. However, there are numerical indications that the
collapse ends in a tamer shell-crossing singularity prior to the formation of
central singularities for mass functions giving a regular conserved mass
density. Moreover, we find quantum gravitational obstructions to the existence
of exactly homogeneous solutions within this class of models. This indicates
that homogeneous models must be seen in a wider context of inhomogeneous
solutions and their reduction in order to provide reliable dynamical
conclusions.


title:
Towards quantitative prediction of proteasomal digestion patterns of
  proteins

abstract:
  We discuss the problem of proteasomal degradation of proteins. Though
proteasomes are important for all aspects of the cellular metabolism, some
details of the physical mechanism of the process remain unknown. We introduce a
stochastic model of the proteasomal degradation of proteins, which accounts for
the protein translocation and the topology of the positioning of cleavage
centers of a proteasome from first principles. For this model we develop the
mathematical description based on a master-equation and techniques for
reconstruction of the cleavage specificity inherent to proteins and the
proteasomal translocation rates, which are a property of the proteasome specie,
from mass spectroscopy data on digestion patterns. With these properties
determined, one can quantitatively predict digestion patterns for new
experimental set-ups. Additionally we design an experimental set-up for a
synthetic polypeptide with a periodic sequence of amino acids, which enables
especially reliable determination of translocation rates.


title:
Benchmarking of 3D space charge codes using direct phase space
  measurements from photoemission high voltage DC gun

abstract:
  We present a comparison between space charge calculations and direct
measurements of the transverse phase space for space charge dominated electron
bunches after a high voltage photoemission DC gun followed by an emittance
compensation solenoid magnet. The measurements were performed using a
double-slit setup for a set of parameters such as charge per bunch and the
solenoid current. The data is compared with detailed simulations using 3D space
charge codes GPT and Parmela3D with initial particle distributions created from
the measured transverse and temporal laser profiles. Beam brightness as a
function of beam fraction is calculated for the measured phase space maps and
found to approach the theoretical maximum set by the thermal energy and
accelerating field at the photocathode.


title:
Theoretical method for the generation of a dark two-mode squeezed state
  of a trapped ion

abstract:
  Here we show how to generate a dark two-mode squeezed state of a trapped ion,
employing a three-level ion in a V configuration with a strong decay of the
excited states. The degree of squeezing can be manipulated by choosing the
intensity of the driving fields. Our scheme is robust against the usual
dissipation mechanism and could be implemented with present-day technology. The
validity of the approximations employed in this work was tested by numerical
calculations, which agreed completely with the analytical solutions.


title: The rational dressing for abelian twisted loop Toda systems

abstract:
  We consider abelian twisted loop Toda equations associated with the complex
general linear groups. The Dodd--Bullough--Mikhailov equation is a simplest
particular case of the equations under consideration. We construct new soliton
solutions of these Toda equations using the method of rational dressing.


title:
Observable estimation of entanglement for arbitrary finite-dimensional
  mixed states

abstract:
  We present observable upper bounds of squared concurrence, which are the dual
inequalities of the observable lower bounds introduced in [F. Mintert and A.
Buchleitner, Phys. Rev. Lett. 98, 140505 (2007)] and [L. Aolita, A. Buchleitner
and F. Mintert, Phys. Rev. A 78, 022308 (2008)]. These bounds can be used to
estimate entanglement for arbitrary experimental unknown finite-dimensional
states by few experimental measurements on a twofold copy $\rho\otimes\rho$ of
the mixed states. Furthermore, the degree of mixing for a mixed state and some
properties of the linear entropy also have certain relations with its upper and
lower bounds of squared concurrence.


title: The combinatorics of k-marked Durfee symbols

abstract:
  Andrews recently introduced k-marked Durfee symbols which are connected to
moments of Dyson's rank. By these connections, Andrews deduced their generating
functions and some combinatorial properties and left their purely combinatorial
proofs as open problems. The primary goal of this article is to provide
combinatorial proofs in answer to Andrews' request. We obtain a relation
between k-marked Durfee symbols and Durfee symbols by constructing bijections,
and all identities on k-marked Durfee symbols given by Andrews could follow
from this relation. In a similar manner, we also prove the identities due to
Andrews on k-marked odd Durfee symbols combinatorially, which resemble ordinary
k-marked Durfee symbols with a modified subscript and with odd numbers as
entries.


title: Fast Excitation and Photon Emission of a Single-Atom-Cavity System

abstract:
  We report on the fast excitation of a single atom coupled to an optical
cavity using laser pulses that are much shorter than all other relevant
processes. The cavity frequency constitutes a control parameter that allows the
creation of single photons in a superposition of two tunable frequencies. Each
photon emitted from the cavity thus exhibits a pronounced amplitude modulation
determined by the oscillatory energy exchange between the atom and the cavity.
Our technique constitutes a versatile tool for future quantum networking
experiments.


title:
Symmetries and exponential error reduction in Yang-Mills theories on the
  lattice

abstract:
  The partition function of a quantum field theory with an exact symmetry can
be decomposed into a sum of functional integrals each giving the contribution
from states with definite symmetry properties. The composition rules of the
corresponding transfer matrix elements can be exploited to devise a multi-level
Monte Carlo integration scheme for computing correlation functions whose
numerical cost, at a fixed precision and at asymptotically large times,
increases power-like with the time extent of the lattice. As a result the
numerical effort is exponentially reduced with respect to the standard Monte
Carlo procedure. We test this strategy in the SU(3) Yang--Mills theory by
evaluating the relative contribution to the partition function of the parity
odd states.


title: Statistical correlations in a Coulomb gas with a test charge

abstract:
  A recent paper [Jokela et al, arxiv:0806.1491 9 June 2008] contains a surmise
about an expectation value in a Coulomb gas which interacts with an additional
charge xi that sits at a fixed position. Here I demonstrate the validity of the
surmised expression and extend it to a certain class of higher cumulants. The
calculation is based on the analogy to statistical averages in the circular
unitary ensemble of random-matrix theory and exploits properties of orthogonal
polynomials on the unit circle.

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


title:
Gravitation in the solar system and metric extensions of general
  relativity

abstract:
  Despite its remarkable agreement with gravity tests in the solar system,
general relativity is challenged at larger scales. Large scale tests performed
in the solar system by the Pioneer 10/11 probes have failed to confirm the
expected gravity laws. We discuss here extensions of general relativity which
preserve its geometrical nature while showing an ability to conciliate the
Pioneer anomalies with other gravity tests. Further testable phenomenological
consequences are also briefly discussed.


title: Canonical toric Fano threefolds

abstract:
  An inductive approach to classifying toric Fano varieties is given. As an
application of this technique, we present a classification of the toric Fano
threefolds with at worst canonical singularities. Up to isomorphism, there are
674,688 such varieties.


title: Simplicity of vacuum modules over affine Lie superalgebras

abstract:
  We prove an explicit condition on the level $k$ for the irreducibility of a
vacuum module $V^{k}$ over a (non-twisted) affine Lie superalgebra, which was
conjectured by M. Gorelik and V.G. Kac. An immediate consequence of this work
is the simplicity conditions for the corresponding minimal W-algebras obtained
via quantum reduction, in all cases except when the level $k$ is a non-negative
integer.


title: Anomalous Returns in a Neural Network Equity-Ranking Predictor

abstract:
  Using an artificial neural network (ANN), a fixed universe of approximately
1500 equities from the Value Line index are rank-ordered by their predicted
price changes over the next quarter. Inputs to the network consist only of the
ten prior quarterly percentage changes in price and in earnings for each equity
(by quarter, not accumulated), converted to a relative rank scaled around zero.
Thirty simulated portfolios are constructed respectively of the 10, 20,..., and
100 top ranking equities (long portfolios), the 10, 20,..., 100 bottom ranking
equities (short portfolios) and their hedged sets (long-short portfolios). In a
29-quarter simulation from the end of the third quarter of 1994 through the
fourth quarter of 2001 that duplicates real-world trading of the same method
employed during 2002, all portfolios are held fixed for one quarter. Results
are compared to the S&P 500, the Value Line universe itself, trading the
universe of equities using the proprietary ``Value Line Ranking System'' (to
which this method is in some ways similar), and to a Martingale method of
ranking the same equities. The cumulative returns generated by the network
predictor significantly exceed those generated by the S&P 500, the overall
universe, the Martingale and Value Line prediction methods and are not eroded
by trading costs. The ANN shows significantly positive Jensen's alpha, i.e.,
anomalous risk-adjusted expected return. A time series of its global
performance shows a clear antipersistence. However, its performance is
significantly better than a simple one-step Martingale predictor, than the
Value Line system itself and than a simple buy and hold strategy, even when
transaction costs are accounted for.


title:
Multi-wavelength source at ITU-T grid based on ultra-flattened
  dispersion photonic crystal fibers

abstract:
  We report on the development of a multi-wavelength source locked to the ITU-T
grid at 100 GHz spacing and based on ultra-flattened dispersion photonic
crystal fibers. The ITU-T grid frequencies are generated by taking advantage of
multiple four-wave mixing processes. We experimentally obtained 250 products
spanning over 200nm by launching 03 strong pump signals. Simulations based on
Split-Step Fourier Method have been carried out in order to investigate and
improve the performance of this nonlinear optical device.


title: Lone Higgs at the LHC

abstract:
  We address the possible scenario that the Large Hadron Collider (LHC)
discovers only a Higgs boson after 10 fb^{-1} of operation, and attempt to
identify this Higgs boson as that of the Standard Model (SM), the minimal
universal extra dimension model (MUED), the littlest Higgs model with T-parity
(LHT), or the minimal supersymmetric Standard Model (MSSM), using only the
measurement of the product of gluon-fusion production cross section and the
di-photon branching ratio. In MUED, by decoupling any new physics sufficiently
to evade the discovery reach at the LHC, the deviation of the signal from the
SM is not statistically significant. However, in LHT and MSSM, it is possible
to have a significant deviation in the signal that is consistent with this
"lone Higgs scenario", and, in the case of a very large suppression, we can
distinguish MSSM and LHT before the discovery of any new resonances. Starting
with the lone Higgs scenario and the deviation in this measurement from the
Standard Model prediction (whether or not statistically significant), we offer
tests that may discriminate the models and search strategies of discovering new
physics signatures with increasing integrated luminosity.


title:
Non-parametric strong lens inversion of Cl~0024+1654: illustrating the
  monopole degeneracy

abstract:
  The cluster lens Cl 0024+1654 is undoubtedly one of the most beautiful
examples of strong gravitational lensing, providing five large images of a
single source with well-resolved substructure. Using the information contained
in the positions and the shapes of the images, combined with the null space
information, a non-parametric technique is used to infer the strong lensing
mass map of the central region of this cluster. This yields a strong lensing
mass of 1.60x10^14 M_O within a 0.5' radius around the cluster center. This
mass distribution is then used as a case study of the monopole degeneracy,
which may be one of the most important degeneracies in gravitational lensing
studies and which is extremely hard to break. We illustrate the monopole
degeneracy by adding circularly symmetric density distributions with zero total
mass to the original mass map of Cl 0024+1654. These redistribute mass in
certain areas of the mass map without affecting the observed images in any way.
We show that the monopole degeneracy and the mass-sheet degeneracy together lie
at the heart of the discrepancies between different gravitational lens
reconstructions that can be found in the literature for a given object, and
that many images/sources, with an overall high image density in the lens plane,
are required to construct an accurate, high-resolution mass map based on
strong-lensing data.


title: Higher-Order Theories of Gravitation

abstract:
  We study higher-order theories of gravitation; in particular, we will focus
our attention on the second-order theory, in which conformal symmetry can be
implemented.


title: Conformal symmetry and quantum localization in space-time

abstract:
  The classical procedures which define the relativistic notion of space-time
can be implemented in the framework of Quantum Field Theory. Only relying on
the conformal symmetries of field propagation, time-frequency transfer and
localization lead to the definition of time-frequency references and positions
in space-time as quantum observables. Quantum positions have a non vanishing
commutator identifying with spin, both observables characterizing quantum
localization in space-time. Frame transformations to accelerated frames differ
from their classical counterparts. Conformal symmetry nevertheless allows to
extend the covariance rules underlying the formalism of general relativity
under an algebraic form suiting the quantum framework.


title: D-Branes on Toric Calabi-Yau Varieties

abstract:
  We analyze B-type D-branes on noncompact toric Calabi--Yau spaces. A general
program is presented to find a set of tilting line bundles that yields the
associated quiver and its relations. In many cases, this set remains fixed as
one moves between phases in the K\"ahler moduli space. This gives a
particularly simple picture of how the derived category remains invariant
across all phases. The combinatorial problems involving local cohomology used
to determine the tilting set are also related to questions of Pi-stability as
one moves between phases. As a result, in some cases precisely those line
bundles in the tilting set remain stable over the whole moduli space in some
sense.


title:
Spin Calogero Particles and Bispectral Solutions of the Matrix KP
  Hierarchy

abstract:
  Pairs of $n\times n$ matrices whose commutator differ from the identity by a
matrix of rank $r$ are used to construct bispectral differential operators with
$r\times r$ matrix coefficients satisfying the Lax equations of the Matrix KP
hierarchy. Moreover, the bispectral involution on these operators has dynamical
significance for the spin Calogero particles system whose phase space such
pairs represent. In the case $r=1$, this reproduces well-known results of
Wilson and others from the 1990's relating (spinless) Calogero-Moser systems to
the bispectrality of (scalar) differential operators. This new class of pairs
$(L, \Lambda)$ of bispectral matrix differential operators is different than
those previously studied in that $L$ acts from the left, but $\Lambda$ from the
right on a common $r\times r$ eigenmatrix.


title: Radiative corrections to pion Compton scattering

abstract:
  We calculate the one-photon loop radiative corrections to charged pion
Compton scattering, $\pi^- \gamma \to \pi^- \gamma $. Ultraviolet and infrared
divergencies are both treated in dimensional regularization. Analytical
expressions for the ${\cal O}(\alpha)$ corrections to the invariant Compton
scattering amplitudes, $A(s,u)$ and $B(s,u)$, are presented for 11 classes of
contributing one-loop diagrams. Infrared finiteness of the virtual radiative
corrections is achieved (in the standard way) by including soft photon
radiation below an energy threshold $\lambda$, and its relation to the
experimental detection threshold is discussed. We find that the radiative
corrections are maximal in backward directions, reaching e.g. -2.4% for a
center-of-mass energy of $\sqrt{s}=4m_\pi$ and $\lambda=5 $MeV. Furthermore, we
extend our calculation of the radiative corrections by including the leading
pion structure effect (at low energies) in form of its electric and magnetic
polarizability difference, $\alpha_\pi - \beta_\pi \simeq 6\cdot 10^{-4}
$fm$^3$. We find that this structure effect does not change the relative size
and angular dependence of the radiative corrections to pion Compton scattering.
Our results are particularly relevant for analyzing the COMPASS experiment at
CERN which aims at measuring the pion electric and magnetic polarizabilities
with high statistics using the Primakoff effect.


title: High Q2 Structure Functions at HERA

abstract:
  The latest results of H1 and ZEUS on the electroweak cross sections using
polarised lepton beams are presented with the improvements in the parton
density functions that result from them. The asymmetry of the neutral current
cross sections between e-p and e+p was measured and shows parity violation in
agreement with the Standard Model. The dependence of the charged current cross
section on the beam polarisation has been obtained and its extrapolation to
full polarisation implies the absence of right-handed charged currents.
Constraints on the vector and axial vector couplings of the u and d quarks to
the Z boson from a combined QCD and electroweak fit are shown and the results
from the combination of H1 and ZEUS data are reviewed.


title:
Quasiparticle Chirality in Epitaxial Graphene Probed at the Nanometer
  Scale

abstract:
  Graphene exhibits unconventional two-dimensional electronic properties
resulting from the symmetry of its quasiparticles, which leads to the concepts
of pseudospin and electronic chirality. Here we report that scanning tunneling
microscopy can be used to probe these unique symmetry properties at the
nanometer scale. They are reflected in the quantum interference pattern
resulting from elastic scattering off impurities, and they can be directly read
from its fast Fourier transform. Our data, complemented by theoretical
calculations, demonstrate that the pseudospin and the electronic chirality in
epitaxial graphene on SiC(0001) correspond to the ones predicted for ideal
graphene.


title: On discrete stochastic processes with long-lasting time dependence

abstract:
  In this manuscript, we analytically and numerically study statistical
properties of an heteroskedastic process based on the celebrated ARCH generator
of random variables whose variance is defined by a memory of
$q_{m}$-exponencial, form ($e_{q_{m}=1}^{x}=e^{x}$). Specifically, we inspect
the self-correlation function of squared random variables as well as the
kurtosis. In addition, by numerical procedures, we infer the stationary
probability density function of both of the heteroskedastic random variables
and the variance, the multiscaling properties, the first-passage times
distribution, and the dependence degree. Finally, we introduce an asymmetric
variance version of the model that enables us to reproduce the so-called
leverage effect in financial markets.


title: A Fresh Look into the Neutron EDM and Magnetic Susceptibility

abstract:
  We reexamine the estimate of the neutron Electric Dipole Moment (NEDM) from
chiral and QCD spectral sum rules (QSSR) approaches. In the former, we evaluate
the pion mass corrections which are about 5% of the leading Log. results.
However, the chiral estimate can be affected by the unknown value of the
renormalizaton scale nu. For QSSR, we analyze the effect of the nucleon
interpolating currents on the existing predictions. We conclude that previous
QSSR results are not obtained within the optimal choice of these operators,
which lead to an overestimate of these results by about a factor 4. The weakest
upper bound |theta|< 2 10^-9 for the strong CP-violating angle is obtained from
QSSR, while the strongest upper bound |theta|< 1.3 10^-10 comes from the chiral
approach evaluated at the scale \nu=M_N. We also re-estimate the proton
magnetic susceptibility, which is an important input in the QSSR estimate of
the NEDM.


title: $H_D$-Quantum Vertex Algebras

abstract:
  We discuss a class of quantum vertex algebras where not only the
commutativity of the vertex algebra is broken by a braiding map $S^{(\tau)}$,
but also the translation covariance is broken by a translation map
$S^{(\gamma)}$. The new class of quantum vertex operators satisfy a Braided
Jacobi Identity containing both the braiding and the translation maps.


title: Dispersion interaction between two atoms in electromagnetic fields

abstract:
  We present a new theory of atom-atom dispersion interaction in the presence
of electromagnetic fields. The theory takes into account the absorption and
emission of virtual photons leading to the resonance contributions to the
interaction potential in the case of non-equilibrium dynamics.


title:
Spin freezing transition and non-Fermi-liquid self-energy in a 3-orbital
  model

abstract:
  A single-site dynamical mean field study of a three band model with the
rotationally invariant interactions appropriate to the t_2g levels of a
transition metal oxide reveals a quantum phase transition between a
paramagnetic metallic phase and an incoherent metallic phase with frozen
moments. The Mott transitions occurring at electron densities n=2,3 per site
take place inside the frozen moment phase. The critical line separating the two
phases is characterized by a self energy with the frequency dependence
\Sigma(\omega)\sim \sqrt{\omega} and a broad quantum critical regime. The
findings are discussed in the context of the power law observed in the optical
conductivity of SrRuO_3.


title: Towards visible CW pumped supercontinua

abstract:
  We report a 1 um continuous wave pumped supercontinuum which extends short of
the pump wavelength to 0.65 um. This is achieved by using a 50 W Yb fibre laser
in combination with a photonic crystal fibre with a carefully engineered zero
dispersion wavelength. We show that the short wavelength generation is due to a
combination of four-wave mixing and dispersive wave trapping by solitons. The
evolution and limiting factors of the continuum are discussed.


title: On reduced models for superstrings on AdS_n x S^n

abstract:
  We review the Pohlmeyer reduction procedure of the superstring sigma model on
AdS_n x S^n leading to a gauged WZW model with an integrable potential coupled
to 2d fermions. In particular, we consider the case of the Green-Schwarz
superstring on AdS_3 x S^3 supported by RR flux. The bosonic part of the
reduced model is given by the sum of the complex sine-Gordon Lagrangian and its
sinh-Gordon counterpart. We determine the corresponding fermionic part and
discuss possible existence of hidden 2d supersymmetry in the reduced action. We
also elaborate on some general aspects of the Pohlmeyer reduction applied to
the AdS_5 x S^5 superstring.


title: Low-energy molecular collisions in a permanent magnetic trap

abstract:
  Cold, neutral hydroxyl radicals are Stark decelerated and confined within a
magnetic trap consisting of two permanent ring magnets. The OH molecules are
trapped in the ro-vibrational ground state at a density of $\sim10^{6}$
cm$^{-3}$ and temperature of 70 mK. Collisions between the trapped OH sample
and supersonic beams of atomic He and molecular D$_{2}$ are observed and
absolute collision cross sections measured. The He--OH and D$_{2}$--OH
center-of-mass collision energies are tuned from 60 cm$^{-1}$ to 230 cm$^{-1}$
and 145 cm$^{-1}$ to 510 cm$^{-1}$, respectively, yielding evidence of reduced
He--OH inelastic cross sections at energies below 84 cm$^{-1}$, the OH ground
rotational level spacing.


title:
On the electronic structure of electron doped LaOFeAs as seen by X-ray
  absorption spectroscopy

abstract:
  We investigated the recently found superconductor LaO_{1-x}F_xFeAs by X-ray
absorption spectroscopy (XAS). From a comparison of the O K-edge with LDA
calculations we find good agreement and are able to explain the structure and
changes of the spectra with electron doping. An important result from this edge
is a limitation of the Hubbard U to values not significantly larger than 1 eV.
  From experimental Fe L_2,3-edge spectra and charge transfer multiplet
calculations we gain further information on important physical values such as
hopping parameters, the charge transfer energy Delta, and the on-site Hubbard
U. Furthermore we find the system to be very covalent with a large amount of
ligand holes. A shift in the chemical potential is visible in the O K- and Fe
L_2,3-edge spectra which emphasizes the importance of band effects in these
compounds.


title: HKT Geometry and de Sitter Supergravity

abstract:
  Solutions of five dimensional minimal de Sitter supergravity admitting
Killing spinors are considered. It is shown that the "timelike'' solutions are
determined in terms of a four dimensional hyper-Kahler torsion (HKT) manifold.
If the HKT manifold is conformally hyper-Kahler the most general solution can
be obtained from a sub-class of supersymmetric solutions of minimal N=2
ungauged supergravity, by means of a simple transformation. Examples include a
multi-BMPV de Sitter solution, describing multiple rotating black holes
co-moving with the expansion of the universe. If the HKT manifold is not
conformally hyper-Kahler, examples admitting a tri-holomorphic Killing vector
field are constructed in terms of certain solutions of three dimensional
Einstein-Weyl geometry.


title:
Electronic structure and exotic exchange splitting in spin-density-wave
  states of BaFe$_2$As$_2$

abstract:
  The magnetic properties in the parent compounds are often intimately related
to the microscopic mechanism of superconductivity. Here we report the first
direct measurements on the electronic structure of a parent compound of the
newly discovered iron-based superconductor, BaFe$_2$As$_2$, which provides a
foundation for further studies. We show that the energy of the spin density
wave (SDW) in BaFe$_2$As$_2$ is lowered through exotic exchange splitting of
the band structure, rather than Fermi surface nesting of itinerant electrons.
This clearly demonstrates that a metallic SDW state could be solely induced by
interactions of local magnetic moments, resembling the nature of
antiferromagnetic order in cuprate parent compounds.


title: Graduate Quantum Mechanics Reform

abstract:
  We address four main areas in which graduate quantum mechanics education can
be improved: course content, textbook, teaching methods, and assessment tools.
We report on a three year longitudinal study at the Colorado School of Mines
using innovations in all these areas. In particular, we have modified the
content of the course to reflect progress in the field in the last 50 years,
used textbooks that include such content, incorporated a variety of teaching
techniques based on physics education research, and used a variety of
assessment tools to study the effectiveness of these reforms. We present a new
assessment tool, the Graduate Quantum Mechanics Conceptual Survey, and further
testing of a previously developed assessment tool, the Quantum Mechanics
Conceptual Survey. We find that graduate students respond well to
research-based techniques that have been tested mainly in introductory courses,
and that they learn much of the new content introduced in each version of the
course. We also find that students' ability to answer conceptual questions
about graduate quantum mechanics is highly correlated with their ability to
solve calculational problems on the same topics. In contrast, we find that
students' understanding of basic undergraduate quantum mechanics concepts at
the modern physics level is not improved by instruction at the graduate level.


title: Abundance variations in the globular cluster M71 (NGC 6838)

abstract:
  Abundance variations in moderately metal-rich globular clusters can give
clues about the formation and chemical enrichment of globular clusters. CN, CH,
Na, Mg and Al indices in spectra of 89 stars of the template metal-rich
globular cluster M71 are measured and implications on internal mixing are
discussed. Stars from the turn-off up to the Red Giant Branch (0.87 $<$ log g
$<$ 4.65) observed with the GMOS multi-object spectrograph at the Gemini-North
telescope are analyzed. Radial velocities, colours, effective temperatures,
gravities and spectral indices are determined for the sample. Previous findings
related to the CN bimodality and CN-CH anticorrelation in stars of M71 are
confirmed. We also find a CN-Na correlation, and Al-Na, as well as an Mg$_2$-Al
anticorrelation. A combination of convective mixing and a primordial pollution
by AG or massive stars in the early stages of globular cluster formation is
required to explain the observations.


title:
Electronic Structure of Prototype AFe_2As_2 and ReOFeAs High-Temperature
  Superconductors: a Comparison

abstract:
  We have performed ab initio LDA calculations of electronic structure of newly
discovered prototype high-temperature superconductors AFe_2As_2 (A=Ba,Sr) and
compared it with previously calculated electronic spectra of ReOFeAs
(Re=La,Ce,Pr,Nd,Sm). In all cases we obtain almost identical densities of
states in rather wide energy interval (up to 1 eV) around the Fermi level.
Energy dispersions are also very similar and almost two-dimensional in this
energy interval, leading to the same basic (minimal) model of electronic
spectra, determined mainly by Fe d-orbitals of FeAs layers. The other
constituents, such as A ions or rare earths Re (or oxygen states) are more or
less irrelevant for superconductivity. LDA Fermi surfaces for AFe_2As_2 are
also very similar to that of ReOFeAs. This makes the more simple AFe_2As_2 a
generic system to study high-temperature superconductivity in FeAs - layered
compounds.


title:
New Experimental limit on Optical Photon Coupling to Neutral, Scalar
  Bosons

abstract:
  We report on the first results of a sensitive search for scalar coupling of
photons to a light neutral boson in the mass range of approximately 1.0
milli-electron volts and coupling strength greater than 10$^-6$ GeV$^-1$ using
optical photons. This was a photon regeneration experiment using the "light
shining through a wall" technique in which laser light was passed through a
strong magnetic field upstream of an optical beam dump; regenerated laser light
was then searched for downstream of a second magnetic field region optically
shielded from the former. Our results show no evidence for scalar coupling in
this region of parameter space.


title: Fubini Theorem for pseudo-Riemannian metrics

abstract:
  We generalize the following classical result of Fubini for pseudo-Riemannian
metrics: if three essentially different metrics on $M^{n\ge 3}$ share the same
unparametrized geodesics, and two of them (say, $g$ and $\bar g$) are strictly
nonproportional (i.e., the minimal polynomial of $g^{i\alpha} \bar g_{\alpha
j}$ coincides with the characteristic polynomial) at least at one point, then
they have constant curvature.


title:
An operator equality involving a continuous field of operators and its
  norm inequalities

abstract:
  Let ${\mathfrak A}$ be a $C^*$-algebra, $T$ be a locally compact Hausdorff
space equipped with a probability measure $P$ and let $(A_t)_{t\in T}$ be a
continuous field of operators in ${\mathfrak A}$ such that the function $t
\mapsto A_t$ is norm continuous on $T$ and the function $t \mapsto \|A_t\|$ is
integrable. Then the following equality including Bouchner integrals holds
\begin{eqnarray}\label{oi} \int_T|A_t - \int_TA_s{\rm d}P|^2 {\rm
d}P=\int_T|A_t|^2{\rm d}P - |\int_TA_t{\rm d}P|^2 . \end{eqnarray} This
equality is related both to the notion of variance in statistics and to a
characterization of inner product spaces. With this operator equality, we
present some uniform norm and Schatten $p$-norm inequalities.


title: Backreaction from non-conformal quantum fields in de Sitter spacetime

abstract:
  We study the backreaction on the mean field geometry due to a non-conformal
quantum field in a Robertson-Walker background. In the regime of small mass and
small deviation from conformal coupling, we compute perturbatively the
expectation value of the stress tensor of the field for a variety of vacuum
states, and use it to obtain explicitly the semiclassical gravity solutions for
isotropic perturbations around de Sitter spacetime, which is found to be
stable. Our results show clearly the crucial role of the non-local terms that
appear in the effective action: they cancel the contribution from local terms
proportional to the logarithm of the scale factor which would otherwise become
dominant at late times and prevent the existence of a stable self-consistent de
Sitter solution. Finally, the opposite regime of a strongly non-conformal field
with a large mass is also considered.


title: Atom as a "Dressed" Nucleus

abstract:
  It is shown that the electrostatic potential of atomic nucleus "seen" by a
fast charged projectile at short distances is smeared quantum mechanically due
to nucleus motion around the atomic center of inertia. For example, the
"positive charge cloud" size in the Hydrogen ground state is much larger than
the proper proton size. It is even bigger for the target atoms in excited
initial states. The elastic scattering at large angles is generally weaker than
the Rutherford one since the effective potential at short distances is softer
than the Colombian one due to a natural "cutoff". In addition, the large angle
scattering leads to the target atom excitations due to pushing the nucleus (=>
inelastic processes). The Rutherford cross section is in fact the inclusive
rather than the elastic one. These results are analogous to the QED ones. The
difference and the value of presented below non relativistic atomic
calculations is in non perturbatively (exact) nucleus "dressing" that
immediately leads to correct physical results and to significant technical
simplifications. In these respects the nucleus bound in an atom is a simple but
a rather realistic model of a "dressed" charge in the QFT. This idea is briefly
demonstrated on the real electron model (electronium) that is made free from
infinities.


title: Evolutionary game dynamics in phenotype space

abstract:
  Evolutionary dynamics can be studied in well-mixed or structured populations.
Population structure typically arises from the heterogeneous distribution of
individuals in physical space or on social networks. Here we introduce a new
type of space to evolutionary game dynamics: phenotype space. The population is
well-mixed in the sense that everyone is equally likely to interact with
everyone else, but the behavioral strategies depend on distance in phenotype
space. Individuals might behave differently towards those who look similar or
dissimilar. Individuals mutate to nearby phenotypes. We study the `phenotypic
space walk' of populations. We present analytic calculations that bring
together ideas from coalescence theory and evolutionary game dynamics. As a
particular example, we investigate the evolution of cooperation in phenotype
space. We obtain a precise condition for natural selection to favor cooperators
over defectors: for a one-dimensional phenotype space and large population size
the critical benefit-to-cost ratio is given by b/c=1+2/sqrt{3}. We derive the
fundamental condition for any evolutionary game and explore higher dimensional
phenotype spaces.


title:
Generation of decoherence-free displaced squeezed states of radiation
  fields and a squeezed reservoir for atoms in cavity QED

abstract:
  We present a way to engineer an effective anti-Jaynes-Cumming and a
Jaynes-Cumming interaction between an atomic system and a single cavity mode
and show how to employ it in reservoir engineering processes. To construct the
effective Hamiltonian, we analyse considered the interaction of an atomic
system in a \{Lambda} configuration, driven by classical fields, with a single
cavity mode. With this interaction, we firstly show how to generate a
decoherence-free displaced squeezed state for the cavity field. In our scheme,
an atomic beam works as a reservoir for the radiation field trapped inside the
cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401
(2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in
high-Q resonators. In our scheme, all the atoms have to be prepared in the
ground state and, as in the cited article, neither atomic detection nor precise
interaction times between the atoms and the cavity mode are required. From this
same interaction, we can also generate an ideal squeezed reservoir for atomic
systems. For this purpose we have to assume, besides the engineered atom-field
interaction, a strong decay of the cavity field (i.e., the cavity decay must be
much stronger than the effective atom-field coupling). With this scheme, some
interesting effects in the dynamics of an atom in a squeezed reservoir could be
tested.


title:
Quantum Conductance and Electronic Properties of Lower Diamondoid
  Molecules and Derivatives

abstract:
  Diamondoids and their derivatives have found major applications as templates
and as molecular building blocks in nanotechnology. Applying ab initio method,
we calculated the quantum conductance and the essential electronic properties
of two lower diamondoids (adamantane and diamantane) and three of their
important derivatives (amantadine, memantine and rimantadine). We also studies
two artificial molecules that are built by substituting one hydrogen ion with
one sodium ion in both adamantane and diamantane molecules. Most of our results
are based on an infinite Au two-probe system constructed by ATK and VNL
software, which comprise TRANSTA-C package. By changing various system
structures and molecule orientations in linear Au and 2 by 2 Au probe systems,
we found that although the conductance of adamantane and diamantane are very
small, the derivatives of the lower diamondoids have considerable conductance
at specific orientations and also showed interesting electronic properties. The
quantum conductance of such molecules will change significantly by changing the
orientations of the molecules, which approves that residues like nitrogen and
sodium atoms have great effects on the conductance and electronic properties of
single molecule. There are obvious peaks near Fermi energy in the transmission
spectrums of artificial molecules, indicating the plateaus in I-V
characteristics of such molecules.


title: A Spitzer view of protoplanetary disks in the gamma Velorum cluster

abstract:
  We present new Spitzer Space Telescope observations of stars in the young ~5
Myr gamma Velorum stellar cluster. Combining optical and 2MASS photometry, we
have selected 579 stars as candidate members of the cluster. With the addition
of the Spitzer mid-infrared data, we have identified 5 debris disks around
A-type stars, and 5-6 debris disks around solar-type stars, indicating that the
strong radiation field in the cluster does not completely suppress the
production of planetesimals in the disks of cluster members. However, we find
some evidence that the frequency of circumstellar primordial disks is lower,
and the IR flux excesses are smaller than for disks around stellar populations
with similar ages. This could be evidence for a relatively fast dissipation of
circumstellar dust by the strong radiation field from the highest mass star(s)
in the cluster. Another possibility is that gamma Velorum stellar cluster is
slightly older than reported ages and the the low frequency of primordial disks
reflects the fast disk dissipation observed at ~5 Myr.


title: An operator algebraic proof of Agler's factorization theorem

abstract:
  We give a short direct proof of Agler's factorization theorem that uses the
abstract characterization of operator algebras. the key ingredient of this
proof is an operator algebra factorization theorem. Our proof provides some
additional information about these factorizations in the case of polynomials.


title:
Effects of Diffusion on Photocurrent Generation in Single-Walled Carbon
  Nanotube Films

abstract:
  We have studied photocurrent generation in large carbon nanotube (CNT) films
using electrodes with different spacings. We observe that the photocurrent
depends strongly on the position of illumination, with maximum observed
response occurring upon illumination at the electrode edges. The rate of change
of the response decays exponentially, with the fastest response occurring for
samples with the smallest electrode spacing. We show that the time response is
due to charge carrier diffusion in low-mobility CNT films.


title:
Gate Tunable Dissipation and "Superconductor-Insulator" Transition in
  Carbon Nanotube Josephson Transistors

abstract:
  Dissipation is ubiquitous in quantum systems, and its interplay with
fluctuations is critical to maintaining quantum coherence. We experimentally
investigate the dissipation dynamics in single-walled carbon nanotubes coupled
to superconductors. The voltage-current characteristics display gate-tunable
hysteresis, with sizes that perfectly correlate with the normal state
resistance RN, indicating the junction undergoes a periodic modulation between
underdamped and overdamped regimes. Surprisingly, when a device's Fermi-level
is tuned through a local conductance minimum, we observe a gate-controlled
transition from superconducting-like to insulating-like states, with a
"critical" R_N value of about 8-20 kohm.


title:
On the Capacity Equivalence with Side Information at Transmitter and
  Receiver

abstract:
  In this paper, a channel that is contaminated by two independent Gaussian
noises $S ~ N(0,Q)$ and $Z_0 ~ N(0,N_0)$ is considered. The capacity of this
channel is computed when independent noisy versions of $S$ are known to the
transmitter and/or receiver. It is shown that the channel capacity is greater
then the capacity when $S$ is completely unknown, but is less then the capacity
when $S$ is perfectly known at the transmitter or receiver. For example, if
there is one noisy version of $S$ known at the transmitter only, the capacity
is $0.5\log(1+\frac{P}{Q(N_1/(Q+N_1))+N_0})$, where $P$ is the input power
constraint and $N_1$ is the power of the noise corrupting $S$. Further, it is
shown that the capacity with knowledge of any independent noisy versions of $S$
at the transmitter is equal to the capacity with knowledge of the statistically
equivalent noisy versions of $S$ at the receiver.


title: Second-order shaped pulses for solid-state quantum computation

abstract:
  We present the constructon and detailed analysis of highly-optimized
self-refocusing pulse shapes for several rotation angles. We characterize the
constructed pulses by the coefficients appearing in the Magnus expansion up to
second order. This allows a semi-analytical analysis of the performance of the
constructed shapes in sequences and composite pulses by computing the
corresponding leading-order error operators. Higher orders can be analyzed with
the numerical technique suggested by us previously. We illustrate the technique
by analysing several composite pulses designed to protect against pulse
amplitude errors, and on decoupling sequences for potentially long chains of
qubits with on-site and nearest-neighbor couplings.


title:
Bounded Ratios of Products of Principal Minors of Positive Definite
  Matrices

abstract:
  Considered is the multiplicative semigroup of ratios of products of principal
minors bounded over all positive definite matrices. A long history of
literature identifies various elements of this semigroup, all of which lie in a
sub-semigroup generated by Hadamard-Fischer inequalities. Via cone-theoretic
techniques and the patterns of nullity among positive semidefinite matrices, a
semigroup containing all bounded ratios is given. This allows the complete
determination of the semigroup of bounded ratios for 4-by-4 positive definite
matrices, whose 46 generators include ratios not implied by Hadamard-Fischer
and ratios not bounded by 1. For n > 4 it is shown that the containment of
semigroups is strict, but a generalization of nullity patterns, of which one
example is given, is conjectured to provide a finite determination of all
bounded ratios.


title: Manifold Learning: The Price of Normalization

abstract:
  We analyze the performance of a class of manifold-learning algorithms that
find their output by minimizing a quadratic form under some normalization
constraints. This class consists of Locally Linear Embedding (LLE), Laplacian
Eigenmap, Local Tangent Space Alignment (LTSA), Hessian Eigenmaps (HLLE), and
Diffusion maps. We present and prove conditions on the manifold that are
necessary for the success of the algorithms. Both the finite sample case and
the limit case are analyzed. We show that there are simple manifolds in which
the necessary conditions are violated, and hence the algorithms cannot recover
the underlying manifolds. Finally, we present numerical results that
demonstrate our claims.


title: Spin magnetosonic shocks in quantum plasmas

abstract:
  The one-dimensional shock structures of magnetosonic waves (MSWs) propagating
in a dissipative quantum plasma medium is studied. A quantum
magnetohydrodynamic (QMHD) model is used to take into account the quantum force
term due to Bohm potential and the pressure-like spin force term for electrons.
The nonlinear evolution (Korteweg de-Vries-Burger) equation, derived to
describe the dynamics of small amplitude MSWs, where the dissipation is
provided by the plasma resistivity, is solved numerically to obtain both
oscillatory and monotonic shock structures. The shock strength decreases with
increasing the effects of collective tunneling and increases with increasing
the effects of spin alignment. The theoretical results could be of importance
for astrophysical (e.g., magnetars) as well as for ultracold laboratory plasmas
(e.g., Rydberg plasmas).


title:
Transport and anisotropy in single-crystalline SrFe$_2$As$_2$ and
  $A_{0.6}$K$_{0.4}$Fe$_2$As$_2$ ($A$ = Sr, Ba) superconductors

abstract:
  We have successfully grown high quality single crystals of SrFe$_2$As$_2$ and
A$_{0.6}$K$_{0.4}$Fe$_2$As$_2$(A=Sr, Ba) using flux method. The resistivity,
specific heat and Hall coefficient have been measured. For parent compound
SrFe$_2$As$_2$, an anisotropic resistivity with $\rho_c$ / $\rho_{ab}$ as large
as 130 is obtained at low temperatures. A sharp drop in both in-plane and
out-plane resistivity due to the SDW instability is observed below 200 K. The
angular dependence of in-plane magnetoresistance shows 2-fold symmetry with
field rotating within ab plane below SDW transition temperature. This is
consistent with a stripe-type spin ordering in SDW state. In K doped
A$_{0.6}$K$_{0.4}$Fe$_2$As$_2$(A=Sr. Ba), the SDW instability is suppressed and
the superconductivity appears with T$_c$ above 35 K. The rather low anisotropy
in upper critical field between H$\parallel$ab and H$\parallel$c indicates
inter-plane coupling play an important role in hole doped Fe-based
superconductors.


title: Hints of theta_13>0 from global neutrino data analysis

abstract:
  Nailing down the unknown neutrino mixing angle theta_13 is one of the most
important goals in current lepton physics. In this context, we perform a global
analysis of neutrino oscillation data, focusing on theta_13, and including
recent results [Neutrino 2008, Proceedings of the XXIII International
Conference on Neutrino Physics and Astrophysics, Christchurch, New Zealand,
2008 (unpublished)]. We discuss two converging hints of theta_13>0, each at the
level of ~1sigma: an older one coming from atmospheric neutrino data, and a
newer one coming from the combination of solar and long-baseline reactor
neutrino data. Their combination provides the global estimate sin^2(theta_13) =
0.016 +- 0.010 (1sigma), implying a preference for \theta_13>0 with
non-negligible statistical significance (~90% C.L.). We discuss possible
refinements of the experimental data analyses, which might sharpen such
intriguing indication.


title: Dust ion-acoustic shocks in quantum dusty pair-ion plasmas

abstract:
  The formation of dust ion-acoustic shocks (DIASs) in a four-component quantum
plasma whose constituents are electrons, both positive and negative ions and
immobile charged dust grains, is studied. The effects of both the dissipation
due to kinematic viscosity and the dispersion caused by the charge separation
as well as the quantum tunneling due to the Bohm potential are taken into
account. The propagation of small but finite amplitude dust ion-acoustic waves
(DIAWs) is governed by the Korteweg-de Vries-Burger (KdVB) equation which
exhibits both oscillatory and monotonic shocks depending not only on the
viscosity parameters, but also on the quantum parameter H (the ratio of the
electron plasmon to the electron Fermi energy) and the positive to negative ion
density ratio. Large amplitude stationary shocks are recovered for a Mach
number exceeding its critical value. Unlike the small amplitude shocks, quite a
smaller value of the viscosity parameter, H and the density ratio may lead to
the large amplitude monotonic shock strucutres. The results could be of
importance in astrophysical and laser produced plasmas.


title: Graphical description of Pauli measurements on stabilizer states

abstract:
  We use a graphical representation of stabilizer states to describe, simply
and efficiently, the effect of measurements of Pauli products on stabilizer
states. This work complements our earlier work [Phys. Rev. A 77, 042307
(2008)], which described in graphical terms the action of Clifford operations
on stabilizer states.


title:
Origin of the spin density wave instability in AFe$_2$As$_2$ (A=Ba, Sr)
  as revealed by optical spectroscopy

abstract:
  We performed optical spectroscopy measurement on single crystals of
BaFe$_2$As$_2$ and SrFe$_2$As$_2$, the parent compounds of FeAs based
superconductors. Both are found to be quite metallic with fairly large plasma
frequencies at high temperature. Upon entering the spin-density-wave (SDW)
state, formation of partial energy gaps was clearly observed with the presence
of surprisingly two different energy scales. A large part of the Drude
component was removed by the gapping of Fermi surfaces (FS). Meanwhile, the
carrier scattering rate was even more dramatically reduced. We elaborate that
the SDW instability is more likely to be driven by the FS nesting of itinerant
electrons rather than a local-exchange mechanism.


title: Modification of the dihadron fragmentation function in nuclear matter

abstract:
  The medium modification of dihadron fragmentation functions in the deeply
inelastic scattering (DIS) off a large nucleus is studied within the framework
of the higher-twist expansion in the collinear factorization formalism. It is
demonstrated that the modification due to multiple parton scattering in the
nuclear medium is similar to that of the single hadron fragmentation function.
However, the conditional distribution of the associated hadron given by the
ratio of dihadron to single hadron fragmentation function shows only slight
modification. The final results depend modestly on the nuclear density
distribution. Comparisons with the experimental results on two hadron
correlations as obtained by the HERMES collaboration at DESY are presented.


title:
Phase and vortex correlations in Josephson-junction arrays at irrational
  frustration

abstract:
  Phase coherence and vortex order in a Josephson-junction array at irrational
frustration are studied by extensive Monte Carlo simulations using the parallel
tempering method. A scaling analysis of the correlation length of phase
variables in the full equilibrated system shows that the critical temperature
vanishes with a power-law divergent correlation length and critical exponent
$\nu_{ph}$, in agreement with recent results from resistivity scaling analysis.
A similar scaling analysis for vortex variables reveals a different critical
exponent $\nu_{v}$, suggesting that there are two distinct correlation lengths
associated with a decoupled zero-temperature phase transition.


title:
Wolf-Rayet Stars in M33 II: Optical Spectroscopy of emission-line stars
  in Giant Hii Regions

abstract:
  We present optical spectra of 14 emission-line stars in M33s giant HII
regions NGC 592, NGC 595 and NGC 604: five of them are known WR stars, for
which we present a better quality spectrogram, eight were WR candidates based
on narrow-band imagery and one is a serendipitous discovery. Spectroscopy
confirms the power of interference filter imagery to detect emission-line stars
down to an equivalent width of about 5 A in crowded fields. We have also used
archival HST/WFPC2 images to correctly identify emission-line stars in NGC 592
and NGC 588. emission-line stars in NGC 592 and NGC 588.


title:
Matched Slow Pulses Using Double Electromagnetically Induced
  Transparency

abstract:
  We implement double electromagnetically-induced transparency (double EIT) in
rubidium vapor, using a tripod-shaped energy level scheme consisting of
hyperfine and magnetic sublevels of the 5S1/2 to 5P1/2 transition. We show
experimentally that through the use of double EIT one can control the contrast
of transparency windows as well as group velocities of the two signal fields.
In particular, the group velocities can be equalized, which holds promise to
greatly enhance nonlinear optical interaction between these fields.


title: Sagnac interference in Carbon nanotubes

abstract:
  The Sagnac interference mode arises when two interfering counterpropogating
beams traverse a loop, but with their velocities detuned by a small amount
$2u$, with $v_{R/L}=v_F\pm u$. In this paper we perform a perturbative
non-equilibrium calculation of Sagnac interference in single channel wires as
well as armchair nanotube loops. We study the dependence of the Sagnac
conductance oscillations on temperature and interactions. We find that the
Sagnac interference is not destroyed by strong interactions, but becomes weakly
dependent on the velocity detuning $u$. In armchairs nanotubes with typical
interaction strength, $0.25 \leq g \leq 0.5$, we find that the necessary
temperature for observing the interference effect, $T_{SAG}$ is also only
weakly dependent on the interaction, and is enhanced by a factor of 8 relative
to the temperature necessary for observing Fabry-Perot interference in the same
system, $T_{FP}$.


title: AGB Connection and Ultraviolet Luminosity Excess in Elliptical Galaxies

abstract:
  Relying on infrared surface brightness fluctuactions to trace AGB properties
in a sample of elliptical galaxies in the Virgo and Fornax clusters, we assess
the puzzling origin of the "UV-upturn" phenomenon, recently traced down to the
presence of a hot horizontal branch stellar component. We find that the
UV-upturn actually signals a profound change in the c-m diagram of stellar
populations in elliptical galaxies, involving both the hot stellar component
and red-giant evolution.


title: A Twisted Kink Crystal in the Chiral Gross-Neveu model

abstract:
  We present the detailed properties of a self-consistent crystalline chiral
condensate in the massless chiral Gross-Neveu model. We show that a suitable
ansatz for the Gorkov resolvent reduces the functional gap equation, for the
inhomogeneous condensate, to a nonlinear Schr\"odinger equation, which is
exactly soluble. The general crystalline solution includes as special cases all
previously known real and complex condensate solutions to the gap equation.
Furthermore, the associated Bogoliubov-de Gennes equation is also soluble with
this inhomogeneous chiral condensate, and the exact spectral properties are
derived. We find an all-orders expansion of the Ginzburg-Landau effective
Lagrangian and show how the gap equation is solved order-by-order.

categories: hep-th cond-mat.supr-con hep-lat math-ph math.MP


title:
Interaction of the magnetorotational instability with hydrodynamic
  turbulence in accretion disks

abstract:
  Accretion disks in which angular momentum transport is dominated by the
magnetorotational instability (MRI) can also possess additional, purely
hydrodynamic, drivers of turbulence. Even when the hydrodynamic processes, on
their own, generate negligible levels of transport, they may still affect the
evolution of the disk via their influence on the MRI. Here, we study the
interaction between the MRI and hydrodynamic turbulence using local MRI
simulations that include hydrodynamic forcing. As expected, we find that
hydrodynamic forcing is generally negligible if it yields a saturated kinetic
energy density that is small compared to the value generated by the MRI. For
stronger hydrodynamic forcing levels, we find that hydrodynamic turbulence
modifies transport, with the effect varying depending upon the spatial scale of
hydrodynamic driving. Large scale forcing boosts transport by an amount that is
approximately linear in the forcing strength, and leaves the character of the
MRI (for example the ratio between Maxwell and Reynolds stresses) unchanged, up
to the point at which the forced turbulence is an order of magnitude stronger
than that generated by the MRI. Low amplitude small scale forcing may modestly
suppress the MRI. We conclude that the impact of hydrodynamic turbulence on the
MRI is generically ignorable in cases, such as convection, where the additional
turbulence arises due to the accretion energy liberated by the MRI itself.
Hydrodynamic turbulence may affect (and either enhance or suppress) the MRI if
it is both strong, and driven by independent mechanisms such as self-gravity,
supernovae, or solid-gas interactions in multiphase protoplanetary disks.


title: Entanglement entropy of two dimensional systems and holography

abstract:
  In this note a new method for computing the entanglement entropy of a CFT
holographically is explored. It consists of finding a bulk background with a
boundary metric that has the conical singularities needed to compute the
entanglement entropy in the usual QFT definition. An explicit calculation is
presented for d=2.


title: Evolution of the First Stars with Dark Matter Burning

abstract:
  Recent theoretical studies have revealed the possibly important role of the
capture and annihilation process of weakly interacting massive particles
(WIMPs) for the first stars. Using new evolutionary models of metal-free
massive stars, we investigate the impact of such ``dark matter burning'' for
the first stars in different environments of dark matter (DM) halos, in terms
of the ambient WIMP density (rho_chi). We find that, in agreement with existing
literature, stellar life times can be significantly prolonged for a certain
range of rho_\chi (i.e., 10^{10} ~ < \rho_\chi GeV/cm3 ~ < 10^{11} with the
current upper limit for the spin-dependent elastic scattering cross section
sigma = 5*10^{-39} cm2}). This greatly enhances the role of rotationally
induced chemical mixing in rotating stars, in favor of abundant production of
primary nitrogen, massive helium stars and long gamma-ray bursts, from the
first stars. We also find that stars with rho_chi > 2*10^{11} GeV/cm3 may not
undergo nuclear burning stages, confirming the previous work, and that ionizing
photon fluxes from such DM supported stars are very weak. Delayed metal
enrichment and slow reionization in the early universe would have resulted if
most of the first stars had been born in DM halos with such high rho_\chi,
unless it had been lowered significantly below the threshold for efficient DM
burning on a short time scale.


title: Influence of Population III stars on cosmic chemical evolution

abstract:
  New observations from the Hubble ultra deep field suggest that the star
formation rate at z>7 drops off faster than previously thought. Using a newly
determined star formation rate for the normal mode of Population II/I stars
(PopII/I), including this new constraint, we compute the Thomson scattering
optical depth and find a result that is marginally consistent with WMAP5
results. We also reconsider the role of Population III stars (PopIII) in light
of cosmological and stellar evolution constraints. While this input may be
needed for reionization, we show that it is essential in order to account for
cosmic chemical evolution in the early Universe. We investigate the
consequences of PopIII stars on the local metallicity distribution function of
the Galactic halo (from the recent Hamburg/ESO survey of metal-poor stars) and
on the evolution of abundances with metallicity (based on the ESO large program
on very metal-poor stars), with special emphasis on carbon-enhanced metal-poor
stars. Our most important results show that the nucleosynthetic yields of
PopIII stars lead to abundance patterns in agreement with those observed in
extremely metal-poor stars. In this chemical approach to cosmic evolution,
PopIII stars prove to be a compulsory ingredient, and extremely metal-poor
stars are inevitably born at high redshift. (Abridged)


title:
Role of bosonic modes in the mechanism of high temperature
  Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ superconductors using ultrafast
  optical techniques

abstract:
  Using ultrafast optical techniques, we probe the hole-doping dependence of
the electron-boson coupling constant $\lambda$ in
Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$. In the overdoped region, we observe a
correlation between ($\lambda$) and the superconducting transition temperature
$T_{c}$. Upon performing the McMillan analysis, however, we find that $\lambda$
is too small to explain the high $T_{c}$'s, and that the Coulomb
pseudopotential $\mu^{\ast}$ is negative. Our analysis therefore reveals two
components in the mechanism of high-$T_{c}$ superconductivity -- a dominant
pre-existing pairing interaction, together with a weaker electron-phonon
interaction that fine-tunes $T_{c}$.


title:
Thermodynamic Properties near the onset of Loop-Current Order in
  high-$T_c$ superconducting cuprates

abstract:
  We have performed large-scale Monte Carlo simulations on a two-dimensional
generalized Ashkin-Teller model to calculate the thermodynamic properties in
the critical region near its transitions. The Ashkin-Teller model has a pair of
Ising spins at each site which interact with neighboring spins through
pair-wise and 4-spin interactions. The model represents the interactions
between orbital current loops in $Cu O_2$-plaquettes of high-$T_c$ cuprates,
which order with a staggered magnetization $\Mso$ inside each unit-cell in the
underdoped region of the phase diagram below a temperature $T^*(x)$ which
depends on doping. The pair of Ising spins per unit-cell represent the
directions of the currents in the links of the current loops. The
generalizations are the inclusion of anisotropy in the pair-wise nearest
neighbor current-current couplings consistent with the symmetries of a square
lattice and the next nearest neighbor pair-wise couplings. We use the Binder
cumulant to estimate the correlation length exponent $\nu$ and the order
parameter exponent $\beta$. Our principal results are that in a range of
parameters, the Ashkin-Teller model as well as its generalization has an order
parameter susceptibility which diverges as $T \to T^*$ and an order parameter
below $T^*$. Importantly, however, there is no divergence in the specific heat.
This puts the properties of the model in accord with the experimental results
in the underdoped cuprates. We also calculate the magnitude of the "bump" in
the specific heat in the critical region to put limits on its observability.
Finally, we show that the staggered magnetization couples to the uniform
magnetization $M_0$ such that the latter has a weak singularity at $T^*$ and
also displays a wide critical region, also in accord with recent experiments.


title:
Origin of X-ray Emission from Transient Black Hole Candidates in
  Quiescence

abstract:
  We report results from a systematic study of X-ray emission from black hole
transients in quiescence. In this state mass accretion is thought to follow the
geometry of an outer optically thick, geometrically thin disc and an inner
optically thin, geometrically thick radiatively inefficient accretion flow
(RIAF). The inner flow is likely also coupled to the jets near the black hole
that are often seen in such systems. The goal of the study is to see whether
the X-ray emission in the quiescent state is mainly powered by the accretion
flow or the jets. Using data from deep XMM-Newton observations of selected
black hole transients, we have found that the quiescent X-ray spectra are, to a
high precision, of power-law shape in the cases of GRO J1655-40 and V404 Cyg.
Such spectra deviate significantly from the expected X-ray spectrum of the RIAF
at very low accretion rates. On the other hand, they can naturally be explained
by emission from the jets, if the emitting electrons follow a power-law
spectral distribution (as is often assumed). The situation remains ambiguous in
the case of XTE J1550-564, due to the relatively poorer quality of the data. We
discuss the implication of the results.


title: String GUT Scenarios with Stabilised Moduli

abstract:
  Taking into account the recently proposed poly-instanton corrections to the
superpotential and combining the race-track with a KKLT respectively LARGE
Volume Scenario in an intricate manner, we show that we gain exponential
control over the parameters in an effective superpotential. This allows us to
dynamically stabilise moduli such that a conventional MSSM scenario with the
string scale lowered to the GUT scale is realised. Depending on the cycles
wrapped by the MSSM branes, two different scenarios for the hierarchy of soft
masses arise. The first one is a supergravity mediated model with M_3/2=1TeV
while the second one features mixed anomaly-supergravity mediation with
M_3/2=10^10GeV and split supersymmetry. We also comment on dynamically lowering
the scales such that the tree-level cosmological constant is of the order
\Lambda=(10^-3eV)^4.


title: Universal Fermi gases in mixed dimensions

abstract:
  We investigate a two-species Fermi gas in which one species is confined in a
two-dimensional plane (2D) or one-dimensional line (1D) while the other is free
in the three-dimensional space (3D). We discuss the realization of such a
system with the interspecies interaction tuned to resonance. When the mass
ratio is in the range 0.0351<m_2D/m_3D<6.35 for the 2D-3D mixture or
0.00646<m_1D/m_3D<2.06 for the 1D-3D mixture, the resulting system is stable
against the Efimov effect and has universal properties. We calculate key
quantities in the many-body phase diagram. Other possible scale-invariant
systems with short-range few-body interactions are also elucidated.


title:
Local Procrustes for Manifold Embedding: A Measure of Embedding Quality
  and Embedding Algorithms

abstract:
  We present the Procrustes measure, a novel measure based on Procrustes
rotation that enables quantitative comparison of the output of manifold-based
embedding algorithms (such as LLE (Roweis and Saul, 2000) and Isomap (Tenenbaum
et al, 2000)). The measure also serves as a natural tool when choosing
dimension-reduction parameters. We also present two novel dimension-reduction
techniques that attempt to minimize the suggested measure, and compare the
results of these techniques to the results of existing algorithms. Finally, we
suggest a simple iterative method that can be used to improve the output of
existing algorithms.


title:
Thermal transport in the anisotropic Heisenberg chain with S = 1/2 and
  nearest-neighbor interactions

abstract:
  The purpose of this note is to connect early work on thermal transport in
spin-1/2 Heisenberg chains with uniaxial exchange anisotropy and
nearest-neighbor interactions that was based on a moment analysis of the
Fourier transform of the energy density correlation function with subsequent
studies that make use of thermal current correlation functions.


title: Evolution of local and global monopole networks

abstract:
  We present an extension of the velocity-dependent one-scale model for cosmic
string evolution, which is suitable for describing the evolution of local and
global monopole networks. We discuss the key dynamical features that need to be
accounted for, in particular the fact that the driving force is due to the
other monopoles (rather than being due to local curvature as in the case of
extended objects) and new forms of energy loss terms due to
monopole-antimonopole capture and annihilation. For the case of local monopoles
we recover and generalize the results of Preskill, suggesting that the scaling
law for the monopole correlation length is very sensitive to the annihilation
rate. On the other hand, for global monopoles the long-range forces generically
lead to linear scaling (just like in the case of local cosmic strings). In this
case we also find good qualitative agreement between our results and the
numerical simulations of Bennett & Rhie and Yamaguchi, although future
high-resolution simulations will be needed for quantitative comparisons.


title: Mediation of Supersymmetry Breaking in a Class of String Theory Models

abstract:
  A consistent theory of supersymmetry breaking must have a hidden sector, an
observable sector, and must be embedded in a locally supersymmetric theory
which arises from string theory. For phenomenological reasons it must also
transmit supersymmetry from the hidden to the visible sector in a dominantly
flavor neutral manner. Also any such theory of supersymmetry breaking has to
take into account the problem of quadratic divergences which arise once the
theory is embedded in supergravity. A class of possible models that arise from
GKP-KKLT type IIB string compactifications, incorporating all this while being
consistent with gauge unification, with just the bare minimum of necessary
supergravity/string theory moduli fields coupled to the minimally
supersymmetric standard model, is presented. Such models give reasonable values
for the soft masses, the $\mu$ and $B\mu$ terms and the gaugino masses.
Assuming that an actual detailed realization exists, it is very likely that
they are the simplest such possibility .


title: Toward directional detection of Dark Matter with the DM-TPC detector

abstract:
  Directional detection can provide unambiguous observation of Dark Matter
interactions even in presence of insidious backgrounds. The DM-TPC
collaboration is developing a detector with the goal of measuring the direction
and sense of nuclear recoils produced in Dark Matter interactions. The detector
consists of a Time Projection Chamber with optical readout filled with CF$_4$
gas at low pressure. A collision between a WIMP and a gas molecule results in a
nuclear recoil of 1-2 mm. The measurement of the energy loss along the recoil
allows us to determine the sense and the direction of the recoil. Results from
a prototype detector operated in a low-energy neutron beam clearly demonstrate
the suitability of this approach to measure directionality. A cubic meter
prototype, which is now being designed, will allow us to set competitive limits
on spin-dependent Dark Matter interactions using a directional detector.


title:
On Certain Large Random Hermitian Jacobi Matrices with Applications to
  Wireless Communications

abstract:
  In this paper we study the spectrum of certain large random Hermitian Jacobi
matrices. These matrices are known to describe certain communication setups. In
particular we are interested in an uplink cellular channel which models mobile
users experiencing a soft-handoff situation under joint multicell decoding.
Considering rather general fading statistics we provide a closed form
expression for the per-cell sum-rate of this channel in high-SNR, when an
intra-cell TDMA protocol is employed. Since the matrices of interest are
tridiagonal, their eigenvectors can be considered as sequences with second
order linear recurrence. Therefore, the problem is reduced to the study of the
exponential growth of products of two by two matrices. For the case where $K$
users are simultaneously active in each cell, we obtain a series of lower and
upper bound on the high-SNR power offset of the per-cell sum-rate, which are
considerably tighter than previously known bounds.


title:
The Cosmic Microwave Background Spectrum and a Determination of Fractal
  Space Dimensionality

abstract:
  The possibility to constrain fractal space dimensionality from Astrophysics
and other areas is briefly reviewed. Assuming such dimensionality to be $3 +
\epsilon$, a limit to $\epsilon$ can be inferred from COBE satellite data. The
available data for the cosmic microwave background radiation spectrum are
fitted by a Planck's radiation distribution generalized to non integer space
dimensionality. Our analysis shows that the shape of the CMBR spectrum, which
does not depend on the absolute normalization, is correctly described from this
distribution provided the absolute temperature is equal to 2.726 $\pm$
$0.003\times 10^{-2}$ K and $\epsilon = - (0.957 \pm 0.006) \times 10^{-5}$.
This value for $\epsilon$ is shown to be consistent with what is found on a
very different spatial scale based on a quantum field phenomenon. The
$|\epsilon|$ is interpreted as an upper limit for how much space dimensionality
could have deviated from three. In other words, this is the maximum fluctuation
space dimensionality should have experienced in a spatial and temporal scale
compared to that of the decoupling era.


title: Real Regulators on Self-Products of K3 Surfaces

abstract:
  Based on a novel application of an archimedean type pairing to the geometry
and deformation theory of $K3$ surfaces, we construct a regulator
indecomposable $K_1$-class on a self-product of a $K3$ surface. In the
Appendix, we explain how this pairing is a special instance of a general
pairing on precycles in the equivalence relation defining Bloch's higher Chow
groups.


title: Optical Metamagnetism and Negative Index Metamaterials

abstract:
  A new class of artificially structured materials called metamaterials makes
it possible to achieve electromagnetic properties that do not exist in nature.
In this paper we review the recent progress made in the area of optical
metamaterials. It was predicted that nanostructured metamaterials could provide
us with artificial magnetic response and negative refractive index at optical
frequencies. To date, optical metamagnetics have been already fabricated to
demonstrate artificial magnetic response in the infrared and across the entire
visible spectrum, while metamaterials showing negative refractive index, also
called negative index materials (NIM), have been demonstrated in the infrared
and at the border with the visible spectral range. Here we report the results
of a sample that displays NIM behavior for red light at a wavelength of 710 nm.
This is the shortest wavelength so far at which NIM behavior has been observed
for light (excluding a device built on surface plasmon polaritons). We also
discuss the fabrication challenges and the impact of fabrication limitations,
specifically surface roughness of the fabricated structures on the optical
properties of the metamaterials.


title: Three Dimensional Lattice-Boltzmann Model for Electrodynamics

abstract:
  In this paper we introduce a novel 3D Lattice-Boltzmann model that recovers
in the continuous limit the Maxwell equations in materials. In order to build
conservation equations with antisymmetric tensors, like the Faraday law, the
model assigns four auxiliary vectors to each velocity vector. These auxiliary
vectors, when combined with the distribution functions, give the
electromagnetic fields. The evolution is driven by the usual BGK collision
rule, but with a different form for the equilibrium distribution functions.
This LBGK model allows us to consider for both dielectrics and conductors with
realistic parameters, and therefore it is adequate to simulate the most diverse
electromagnetic problems, like the propagation of electromagnetic waves (both
in dielectric media and in waveguides), the skin effect, the radiation pattern
of a small dipole antenna and the natural frequencies of a resonant cavity, all
with 2% accuracy. Actually, it shows to be one order of magnitude faster than
the original FDTD formulation by Yee to reach the same accuracy. It is,
therefore, a valuable alternative to simulate electromagnetic fields and opens
lattice Boltzmann for a broad spectrum of new applications in electrodynamics.
In this paper we develop a 3D Lattice-Boltzmann model that recovers in the
continuous limit the Maxwell equations for macroscopic mediums. The model can
sucessfully reproduces the propagation of the electromagnetic waves in
dielectric mediums and waveguide, the skin effect, the electrical dipole
radiation and the electromagnetic response of a resonant cavity.


title:
Quantum corrections to static solutions of Nahm equation and Sin-Gordon
  models via generalized zeta-function

abstract:
  One-dimensional Yang-Mills Equations are considered from a point of view of a
class of nonlinear Klein-Gordon-Fock models. The case of self-dual Nahm
equations and non-self-dual models are discussed. A quasiclassical quantization
of the models is performed by means of generalized zeta-function and its
representation in terms of a Green function diagonal for a heat equation with
the correspondent potential. It is used to evaluate the functional integral and
quantum corrections to mass in the quasiclassical approximation.
  Quantum corrections to a few periodic (and kink) solutions of the Nahm as a
particular case of the Ginzburg-Landau (phi-in-quadro) and and Sin-Gordon
models are evaluated in arbitrary dimensions. The Green function diagonal for
heat equation with a finite-gap potential is constructed by universal
description via solutions of Hermit equation. An alternative approach based on
Baker-Akhiezer functions for KP equation is proposed . The generalized
zeta-function and its derivative at zero point as the quantum corrections to
mass is expressed in terms of elliptic integrals.


title: Data-Oblivious Stream Productivity

abstract:
  We are concerned with demonstrating productivity of specifications of
infinite streams of data, based on orthogonal rewrite rules. In general, this
property is undecidable, but for restricted formats computable sufficient
conditions can be obtained. The usual analysis disregards the identity of data,
thus leading to approaches that we call data-oblivious. We present a method
that is provably optimal among all such data-oblivious approaches. This means
that in order to improve on the algorithm in this paper one has to proceed in a
data-aware fashion.


title: Dark Matter annihilations in Pop III stars

abstract:
  We study the impact of the capture and annihilation of Weakly Interacting
Massive Particles (WIMPs) on the evolution of Pop III stars. With a suitable
modification of the Geneva stellar evolution code, we study the evolution of 20
and 200 M$_\odot$ stars in Dark Matter Haloes with densities between 10$^{8}$
and $10^{11}$ GeV/cm$^3$ during the core H-burning phase, and, for selected
cases, until the end of the core He-burning phase. We find that for WIMP
densities higher than 5.3 $10^{10}(\sigma^{SD}_p/10^{-38} {cm}^2)^{-1}$ GeV
cm$^{-3}$ the core H-burning lifetime of $20 M_{\odot}$ and $200 M_{\odot}$
stars exceeds the age of the Universe, and stars are sustained only by WIMP
annihilations. We determine the observational properties of these `frozen`
objects and show that they can be searched for in the local Universe thanks to
their anomalous mass-radius relation, which should allow unambiguous
discrimination from normal stars.


title: Weighted Superimposed Codes and Constrained Integer Compressed Sensing

abstract:
  We introduce a new family of codes, termed weighted superimposed codes
(WSCs). This family generalizes the class of Euclidean superimposed codes
(ESCs), used in multiuser identification systems. WSCs allow for discriminating
all bounded, integer-valued linear combinations of real-valued codewords that
satisfy prescribed norm and non-negativity constraints. By design, WSCs are
inherently noise tolerant. Therefore, these codes can be seen as special
instances of robust compressed sensing schemes. The main results of the paper
are lower and upper bounds on the largest achievable code rates of several
classes of WSCs. These bounds suggest that with the codeword and weighting
vector constraints at hand, one can improve the code rates achievable by
standard compressive sensing.


title: Conformal transformations and conformal invariance in gravitation

abstract:
  Conformal transformations are frequently used tools in order to study
relations between various theories of gravity and the Einstein relativity. In
this paper we discuss the rules of these transformations for geometric
quantities as well as for the matter energy-momentum tensor. We show the
subtlety of the matter energy-momentum conservation law which refers to the
fact that the conformal transformation "creates" an extra matter term composed
of the conformal factor which enters the conservation law. In an extreme case
of the flat original spacetime the matter is "created" due to work done by the
conformal transformation to bend the spacetime which was originally flat. We
discuss how to construct the conformally invariant gravity theories and also
find the conformal transformation rules for the curvature invariants $R^2$,
$R_{ab}R^{ab}$, $R_{abcd}R^{abcd}$ and the Gauss-Bonnet invariant in a
spacetime of an arbitrary dimension. Finally, we present the conformal
transformation rules in the fashion of the duality transformations of the
superstring theory. In such a case the transitions between conformal frames
reduce to a simple change of the sign of a redefined conformal factor.


title:
Unconditional Security of Single-Photon Differential Phase Shift Quantum
  Key Distribution

abstract:
  In this Letter, we prove the unconditional security of single-photon
differential phase shift quantum key distribution (DPS-QKD) protocol, based on
the conversion to an equivalent entanglement-based protocol. We estimate the
upper bound of the phase error rate from the bit error rate, and show that
DPS-QKD can generate unconditionally secure key when the bit error rate is not
greater than 4.12%. This proof is the first step to the unconditional security
proof of coherent state DPS-QKD.


title:
RAId_aPS: MS/MS analysis with multiple scoring functions and
  spectrum-specific statistics

abstract:
  Statistically meaningful comparison/combination of peptide identification
results from various search methods is impeded by the lack of a universal
statistical standard. Providing an E-value calibration protocol, we
demonstrated earlier the feasibility of translating either the score or
heuristic E-value reported by any method into the textbook-defined E-value,
which may serve as the universal statistical standard. This protocol, although
robust, may lose spectrum-specific statistics and might require a new
calibration when changes in experimental setup occur. To mitigate these issues,
we developed a new MS/MS search tool, RAId_aPS, that is able to provide
spectrum-specific E-values for additive scoring functions. Given a selection of
scoring functions out of RAId score, K-score, Hyperscore and XCorr, RAId_aPS
generates the corresponding score histograms of all possible peptides using
dynamic programming. Using these score histograms to assign E-values enables a
calibration-free protocol for accurate significance assignment for each scoring
function. RAId_aPS features four different modes: (i) compute the total number
of possible peptides for a given molecular mass range, (ii) generate the score
histogram given a MS/MS spectrum and a scoring function, (iii) reassign
E-values for a list of candidate peptides given a MS/MS spectrum and the
scoring functions chosen, and (iv) perform database searches using selected
scoring functions. In modes (iii) and (iv), RAId_aPS is also capable of
combining results from different scoring functions using spectrum-specific
statistics. The web link is
http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/raid_aps/index.html. Relevant
binaries for Linux, Windows, and Mac OS X are available from the same page.


title:
Symmetric polynomials, p-norm inequalities, and certain functionals
  related to majorization

abstract:
  We study a variant of the majorization relation. In particular we consider
inequalities involving some Schur-concave symmetric polynomials related to the
multinomial expansion. We also discuss how these topics were motivated by
conjectures on sharp Lp inequalities between complex exponential sums
conjectured by Hardy and Littlewood (still open problems), and why the usual
majorization relation does not hold in that context.


title: Forward Production of Protons and Pions in Heavy-ion Collisions

abstract:
  The problem of forward production of hadrons in heavy-ion collision at RHIC
is revisited with modification of the theoretical treatment on the one hand and
with the use of new data on the other. The basic formalism for hadronization
remains the same as before, namely, recombination, but the details of momentum
degradation and quark regeneration are improved. Recent data on the p/pi and
pbar/p ratios are used to constrain the value of the degradation parameter. The
p_T spectrum of the average charged particles is well reproduced. A prediction
on the p_T dependence of the pbar/p ratio at eta=3.2 is made.


title: Canonical integral structures on the de Rham cohomology of curves

abstract:
  For a smooth and proper curve X over the fraction field K of a discrete
valuation ring R, we explain (under very mild hypotheses) how to equip the de
Rham cohomology H^1_{dR}(X/K) with a canonical integral structure: i.e. an
R-lattice which is functorial in finite (generically etale) K-morphisms of X
and which is preserved by the cup-product auto-duality on H^1_{dR}(X/K). Our
construction of this lattice uses a certain class of normal proper models of X
and relative dualizing sheaves. We show that our lattice naturally contains the
lattice furnished by the (truncated) de Rham complex of a regular proper
R-model of X and that the index for this inclusion of lattices is a numerical
invariant of X (we call it the de Rham conductor). Using work of Bloch and
Liu-Saito, we prove that the de Rham conductor of X is bounded above by the
Artin conductor, and bounded below by the Efficient conductor. We then study
how the position of our canonical lattice inside the de Rham cohomology of X is
affected by finite extension of scalars.


title: The development of generalized synchronization on complex networks

abstract:
  In this paper, we investigate the development of generalized synchronization
(GS) on typical complex networks, such as scale-free networks, small-world
networks, random networks and modular networks. By adopting the
auxiliary-system approach to networks, we show that GS can take place in
oscillator networks with both heterogeneous and homogeneous degree
distribution, regardless of whether the coupled chaotic oscillators are
identical or nonidentical. For coupled identical oscillators on networks, we
find that there exists a general bifurcation path from initial
non-synchronization to final global complete synchronization (CS) via GS as the
coupling strength is increased. For coupled nonidentical oscillators on
networks, we further reveal how network topology competes with the local
dynamics to dominate the development of GS on networks. Especially, we analyze
how different coupling strategies affect the development of GS on complex
networks. Our findings provide a further understanding for the occurrence and
development of collective behavior in complex networks.


title: An introduction to quantum cluster methods

abstract:
  These lecture notes provide an introduction to quantum cluster methods for
strongly correlated systems. Cluster Perturbation Theory (CPT), the Variational
Cluster Approximation (VCA) and Cellular Dynamical Mean Field Theory (CDMFT)
are described, as well as the exact diagonalization solver for the cluster.
Potthoff's self-energy functional formalism is reviewed. Some numerical
procedures, in particular regarding the exact diagonalization method and the
frequency-momentum integrals needed in VCA, are discussed in detail.


title: Strategies for triple-donor devices fabricated by ion implantation

abstract:
  Triple donor devices have the potential to exhibit adiabatic tunneling via
the CTAP (Coherent Tunneling Adiabatic Passage) protocol which is a candidate
transport mechanism for scalable quantum computing. We examine theoretically
the statistics of dopant placement using counted ion implantation by employing
an analytical treatment of CTAP transport properties under hydrogenic
assumptions. We determine theoretical device yields for proof of concept
devices for different implant energies. In particular, we determine a
significant theoretical device yield (~80%) for 14keV phosphorus in silicon
with nominal 20nm spacing.


title:
Dynamics of magnetization in frustrated spin-chain systems:
  Ca$_3$Co$_2$O$_6$

abstract:
  The magnetization dynamics of the triangular lattice of Ising spin chains is
investigated in the framework of a two-dimensional model. The rigid chains are
assumed to interact with the nearest neighboring chains, an external magnetic
field, and a heat reservoir that causes the chains to change their states
randomly with time. A probability of a single spin-flip process is assumed in a
Glauber-like form. This technique allows describing properly the steps in the
magnetization curves observed in Ca$_3$Co$_2$O$_6$ and their dependence on a
magnetic field sweep rate and temperature. A transition from a low-temperature
to high-temperature phase is also observed.


title: Higgs-Higgsino-Gaugino Induced Two Loop Electric Dipole Moments

abstract:
  We compute the complete set of Higgs-mediated chargino-neutralino two-loop
contributions to the electric dipole moments (EDMs) of the electron and neutron
in the minimal supersymmetric standard model (MSSM). We study the dependence of
these contributions on the parameters that govern CP-violation in the MSSM
gauge-gaugino-Higgs-Higgsino sector. We find that contributions mediated by the
exchange of W H^\pm and Z A^0 pairs, where H^\pm and A^0 are the charged and
CP-odd Higgs scalars, respectively, are comparable to or dominate over those
mediated by the exchange of neutral gauge bosons and CP-even Higgs scalars. We
also emphasize that the result of this complete set of diagrams is essential
for the full quantitative study of a number of phenomenological issues, such as
electric dipole moment searches and their implications for electroweak
baryogenesis.