title: Moduli Spaces of Semistable Sheaves on Singular Genus One Curves

abstract:
  We find some equivalences of the derived category of coherent sheaves on a
Gorenstein genus one curve that preserve the (semi)-stability of pure
dimensional sheaves. Using them we establish new identifications between
certain Simpson moduli spaces of semistable sheaves on the curve. For rank
zero, the moduli spaces are symmetric powers of the curve whilst for a fixed
positive rank there are only a finite number of non-isomorphic spaces. We prove
similar results for the relative semistable moduli spaces on an arbitrary genus
one fibration with no conditions either on the base or on the total space. For
a cycle $E_N$ of projective lines, we show that the unique degree 0 stable
sheaves are the line bundles having degree 0 on every irreducible component and
the sheaves $\mathcal{O}(-1)$ supported on one irreducible component. We also
prove that the connected component of the moduli space that contains vector
bundles of rank $r$ is isomorphic to the $r$-th symmetric product of the
rational curve with one node.


title: Nodal distances for rooted phylogenetic trees

abstract:
  Dissimilarity measures for (possibly weighted) phylogenetic trees based on
the comparison of their vectors of path lengths between pairs of taxa, have
been present in the systematics literature since the early seventies. But, as
far as rooted phylogenetic trees goes, these vectors can only separate
non-weighted binary trees, and therefore these dissimilarity measures are
metrics only on this class. In this paper we overcome this problem, by
splitting in a suitable way each path length between two taxa into two lengths.
We prove that the resulting splitted path lengths matrices single out arbitrary
rooted phylogenetic trees with nested taxa and arcs weighted in the set of
positive real numbers. This allows the definition of metrics on this general
class by comparing these matrices by means of metrics in spaces of real-valued
$n\times n$ matrices. We conclude this paper by establishing some basic facts
about the metrics for non-weighted phylogenetic trees defined in this way using
$L^p$ metrics on these spaces of matrices.


title: On Maxwell's equations unified with the dynamics of cold dark matter

abstract:
  New simple field equations are proposed (Eqs. (5)), unifying Maxwell's
equations of the Standard Model electrodynamics (after the electroweak symmetry
is spontaneously broken) with the dynamics of cold dark matter. The cold dark
matter is represented here by sterile spin-1/2 Dirac fermions (sterinos) whose
mass is spontaneously generated by the nonzero vacuum expectation value of a
field of sterile scalars (sterons), while their interactions are mediated by
quanta of a sterile antisymmetric tensor field with a large mass. The new field
equations include a specific weak coupling of the Standard Model
electromagnetic field to the sterile fields. It has a spontaneous
quasi-magnetic structure. Such a coupling opens a photonic portal between the
Standard Model world and the sterile world.


title: Leggett inequalities and the completeness of quantum mechanics

abstract:
  We consider the so called Legget inequalities which are deduced from the
assumption of general (local or non-local) realism plus the arrow of time
preservation. Then, instead of assuming cryto-nonlocal hidden variables, we
assume any (local or non-local) realism compatible with the joint and non-joint
expected values dictated by quantum mwechaanics. Hence, we prove that this
double assumption is not consistent, since the corresponding general Leggett
inequalities are violated by quantum mechanics. Thus, realism plus arrow of
time preservation and quntum mechanics are not compatible. In other words,
quantum mechanics cannot be completed with any (local or non-local) hidden
variables, provide we assume the common sense of the arrow of time. The result
would deserve to be experimentally tested and we discuss why it is not
invalidated by hidden variable theories as the one from Bohm.


title: A commuting derivations theorem on UFDs

abstract:
  Let $A$ be the polynomial ring over $k$ (a field of characteristic zero) in
$n+1$ variables. The commuting derivations conjecture states that $n$ commuting
locally nilpotent derivations on $A$, linearly independent over $A$, must
satisfy $A^{D_1,...,D_m}=k[f]$ where $f$ is a coordinate. The conjecture can be
formulated as stating that a $(G_m)^n$-action on $k^{n+1}$ must have invariant
ring $k[f]$ where $f$ is a coordinate. In this paper we prove a statement
(theorem \ref{CDH2}) where we assume less on $A$ ($A$ is a {\sc UFD} over $k$
of transcendence degree $n+1$ satisfying $A^*=k$) and prove less
($A/(f-\alpha)$ is a polynomial ring for all but finitely many $\alpha$). Under
certain additional conditions (the $D_i$ are linearly independent modulo
$(f-\alpha)$ for each $\alpha\in k$) we prove that $A$ is a polynomial ring
itself and $f$ is a coordinate. This statement is proven even more generally by
replacing ``free unipotent action of dimension $n$'' for ``$G_a^n$-action''.
  We make links with the (Abhyankar-)Sataye conjecture and give a new
equivalent formulation of the Sataye conjecture.


title: Multi-rate asynchronous sampling of bandwidth-limited signals

abstract:
  We demonstrate experimentally an optical system for under-sampling several
bandwidth limited signals with carrier frequencies that are not known apriori
that can be located anywhere within a very broad frequency region between 0-18
GHz. The system is based on under-sampling asynchronously at three different
sampling rates. The pulses required for the under-sampling are generated by a
combination of an electrical comb generator and an electro-absorption
modulator. To reduce loss and improve performance the implementation of the
optical system is based on a wavelength division multiplexing technique. An
accurate reconstruction of both the phase and the amplitude of the signals was
obtained when two chirped signals generated simultaneously were sampled.


title:
The Red Sequence of High-Redshift Clusters: a Comparison with
  Cosmological Galaxy Formation Models

abstract:
  We compare the results from a semi-analytic model of galaxy formation with
spectro-photometric observations of distant galaxy clusters observed in the
range 0.8< z< 1.3. We investigate the properties of their red sequence (RS)
galaxies and compare them with those of the field at the same redshift. In our
model we find that i) a well-defined, narrow RS is obtained already by z= 1.2;
this is found to be more populated than the field RS, analogously to what
observed and predicted at z=0; ii) the predicted U-V rest-frame colors and
scatter of the cluster RS at z=1.2 have average values of 1 and 0.15
respectively, with a cluster-to-cluster variance of 0.2 and 0.06, respectively.
The scatter of the RS of cluster galaxies is around 5 times smaller than the
corresponding field value; iii) when the RS galaxies are considered, the mass
growth histories of field and cluster galaxies at z=1.2 are similar, with 90 %
of the stellar mass of RS galaxies at z=1.2 already formed at cosmic times
t=2.5 Gyr, and 50 % at t=1 Gyr; v) the predicted distribution of stellar ages
of RS galaxies at z=1.2 peaks at 3.7 Gyr for both cluster and field
populations; however, for the latter the distribution is significantly skewed
toward lower ages. When compared with observations, the above findings show an
overall consistency, although the average value 0.07 of the observed cluster RS
scatter (U-V colors) at z=1.2 is smaller than the corresponding model central
value. We discuss the physical origin and the significance of the above results
in the framework of cosmological galaxy formation.


title: Dynamic domain walls in Maxwell-Dilaton background

abstract:
  Motivated by the well know Chamblin-Reall solutions of $n$-dimensional
background spacetime in a dilaton gravity and the dynamics of a domain wall in
the same backgrounds, we have tried to generalize those solutions by including
electromagnetic field in the bulk. The electromagnetic field is assumed to be
coupled with the scalar field in an exponential way. Under the specific
relations among the various parameters in our model, we have found five
different types of solutions. For every case, the solution has singularity. In
these backgrounds, we have also studied the dynamics of domain wall. The energy
densities which play the role of these interesting dynamics, are know to be
induced from the bulk fields through Israel junction condition. In this more
general background field configuration, we have again found many occasions to
exist static bulk spactime consistent with the dynamic domain wall. In several
cases, depending upon the values of the parameters, in the early stage of
evolution, the domain wall is found to have an inflationary phase for finite
period of it's proper time followed by usual decelerated expansion.


title:
Measurements of radio propagation in rock salt for the detection of
  high-energy neutrinos

abstract:
  We present measurements of the transmission of radio/microwave pulses through
salt in the Cote Blanche salt mine operated by the North American Salt Company
in St. Mary Parish, Louisiana. These results are from data taken in the
southwestern region of the 1500 ft. (457 m) deep level of the mine on our third
and most recent visit to the mine. We transmitted and received a fast,
high-power, broadband pulse from within three vertical boreholes that were
drilled to depths of 100 ft. (30 m) and 200 ft. below the 1500 ft. level using
three different pairs of dipole antennas whose bandwidths span 125 to 900 MHz.
By measuring the relative strength of the received pulses between boreholes
with separations of 50 m and 169 m, we deduce the attenuation of the signal
attributed to the salt medium. We fit the frequency dependence of the
attenuation to a power law and find the best fit field attenuation lengths to
be 93 \pm 7 m at 150 MHz, 63 \pm 3 m at 300 MHz, and 36 \pm 2 m at 800 MHz.
This is the most precise measurement of radio attenuation in a natural salt
formation to date. We assess the implications of this measurement for a future
neutrino detector in salt.


title: Extraction of Resonances from Meson-Nucleon Reactions

abstract:
  We present a pedagogical study of the commonly employed Speed-Plot (SP) and
Time-delay (TD) methods for extracting the resonance parameters from the data
of two particle coupled-channels reactions. Within several exactly solvable
models, it is found that these two methods find poles on different Riemann
sheets and are not always valid. We then develop an analytic continuation
method for extracting the nucleon resonances within a dynamical coupled-channel
formulation of the $\pi N$ and $\gamma N$ reactions. The main focus is on
resolving the complications due to the coupling with the unstable $\pi \Delta,
\rho N, \sigma N$ channels which decay into $\pi \pi N$ states. By using the
results from the considered exactly solvable models, explicit numerical
procedures are presented and verified. As a first application of the developed
analytic continuation method, we present the nucleon resonances in the $S_{11}$
and $S_{31}$ partial waves extracted within a recently developed
coupled-channels model of $\pi N$ reactions. The results from this realistic
$\pi N$ model, which includes $\pi N$, $\eta N$, $\pi\Delta$, $\rho N$, and
$\sigma N$ channels, also show that the simple pole parametrization of the
resonant propagator using the poles extracted from SP and TD methods works
poorly.


title: Stochastic calculus for symmetric Markov processes

abstract:
  Using time-reversal, we introduce a stochastic integral for zero-energy
additive functionals of symmetric Markov processes, extending earlier work of
S. Nakao. Various properties of such stochastic integrals are discussed and an
It\^{o} formula for Dirichlet processes is obtained.


title:
Robust entanglement of a micromechanical resonator with output optical
  fields

abstract:
  We perform an analysis of the optomechanical entanglement between the
experimentally detectable output field of an optical cavity and a vibrating
cavity end-mirror. We show that by a proper choice of the readout (mainly by a
proper choice of detection bandwidth) one can not only detect the already
predicted intracavity entanglement but also optimize and increase it. This
entanglement is explained as being generated by a scattering process owing to
which strong quantum correlations between the mirror and the optical Stokes
sideband are created. All-optical entanglement between scattered sidebands is
also predicted and it is shown that the mechanical resonator and the two
sideband modes form a fully tripartite-entangled system capable of providing
practicable and robust solutions for continuous variable quantum communication
protocols.


title: Tau air showers detectability with GLAST

abstract:
  We show that with GLAST there will be the possibility to detect, within the
UHECR skimming at atmosphere edges, the showers generated by very high energy
upward and horizontal Tau. The effective area, thanks to the large area covered
by the showers at 550 Km, is less than that of AUGER, but its efficiency is
comparable because the lower detection threshold and the consequent event rate
may lead to a few EeV and-or few Glashow resonant signals within a decade.


title:
Magnetic fields and star formation in galaxies of different
  morphological types

abstract:
  From our radio continuum and polarization observations of a sample of spiral
galaxies with different morphological types, inclinations, and star formation
rates (SFR) we found that galaxies with low SFR have higher thermal fractions/
smaller synchrotron fractions than those with normal or high SFR. Adopting an
equipartition model, we concluded from our observations that the nonthermal
radio emission and the total magnetic field strength grow nonlinearly with SFR.
We also studied the magnetic field structure and disk thicknesses in highly
inclined (edge-on) galaxies. We found in five galaxies that - despite their
different radio appearance - the vertical scale heights for both, the thin and
thick disk/halo, are about equal (0.3/1.8kpc), independently of their different
SFR. They also show a similar large-scale magnetic field configuration,
parallel to the midplane and X-shaped further away from the disk plane,
independent of Hubble type and SFR in the disk. Hence we conclude that the
amplification and formation of the large-scale magnetic field structure is
independent of SFR.


title:
A Novel Non perturbative Self-consistent and General Approximation
  Method in Quantum Theory

abstract:
  A new method of approximation scheme with potential application to a general
interacting quantum system is presented. The method is non-perturbative, self-
consistent, systematically improvable and uniformly applicable for arbitrary
strength of interaction. It thus overcomes the various limitations of the
exsting methods such as the perturbation theory, the variational method, the
WKBJ method and other approximation schemes. The current method has been
successfully applied to a variety of interacting systems including the
anharmonic/ double-well oscillators (with quartic-, sextic- and octic
couplings) and the scalar field theory with quartic-coupling in the symmetric
phase. The method yields important insight in to the structure and stability of
the interacting-vacuum of the theory. The results are in good agreement with
the exact predictions of supersymmetry where ever applicable. Possible further
applications in the areas of quantum statistics, finite temperature field
theory, condensed matter physics etc are also discussed.


title:
Vibrational spectroscopy of H2+: hyperfine structure of two-photon
  transitions

abstract:
  We present the computation of two-photon transition spectra between
ro-vibrational states of the H2+ molecular ion, including the effects of
hyperfine structure and excitation polarization. The reduced two-photon matrix
elements are obtained by means of a variational method. We discuss the
implications of our results for high-resolution spectroscopy of H2+.


title: Dense electron-hole plasma in silicon light emitting diodes

abstract:
  Efficient electroluminescence of silicon light emitting p-n diodes with
different sizes and shapes is investigated at room temperature. High quantum
efficiency of the diodes, a long linear dependence of the electroluminescence
intensity on the diode current and a low energy shift of the emission line in
electroluminescence spectra with increasing diode current are explained by the
self-compression of injected electron-hole plasma into dense electron-hole
plasma drops. Experiments on space scanning of the electroluminescence
intensity of the diodes support this conclusion. The plasma self-compression is
explained by existence of an attraction in electron-hole plasma, compensating
the plasma pressure. A decrease of the semiconductor energy gap due to a local
lattice overheating, produced by the plasma, and the exchange-correlation
interaction could contribute to this attraction. The self-focusing of the
injection current can accompany the plasma self-compression.


title:
A classification of near-horizon geometries of extremal vacuum black
  holes

abstract:
  We consider the near-horizon geometries of extremal, rotating black hole
solutions of the vacuum Einstein equations, including a negative cosmological
constant, in four and five dimensions. We assume the existence of one
rotational symmetry in 4d, two commuting rotational symmetries in 5d and in
both cases non-toroidal horizon topology. In 4d we determine the most general
near-horizon geometry of such a black hole, and prove it is the same as the
near-horizon limit of the extremal Kerr-AdS(4) black hole. In 5d, without a
cosmological constant, we determine all possible near-horizon geometries of
such black holes. We prove that the only possibilities are one family with a
topologically S^1 X S^2 horizon and two distinct families with topologically
S^3 horizons. The S^1 X S^2 family contains the near-horizon limit of the
boosted extremal Kerr string and the extremal vacuum black ring. The first
topologically spherical case is identical to the near-horizon limit of two
different black hole solutions: the extremal Myers-Perry black hole and the
slowly rotating extremal Kaluza-Klein (KK) black hole. The second topologically
spherical case contains the near-horizon limit of the fast rotating extremal KK
black hole. Finally, in 5d with a negative cosmological constant, we reduce the
problem to solving a sixth-order non-linear ODE of one function. This allows us
to recover the near-horizon limit of the known, topologically S^3, extremal
rotating AdS(5) black hole. Further, we construct an approximate solution
corresponding to the near-horizon geometry of a small, extremal AdS(5) black
ring.


title: Vibrational spectroscopy of H2+: precise evaluation of the Zeeman effect

abstract:
  We present an accurate computation of the g-factors of the hyperfine states
of the hydrogen molecular ion H2+. The results are in good agreement with
previous experiments, and can be tested further by rf spectroscopy. Their
implication for high-precision two-photon vibrational spectroscopy of H2+ is
also discussed. It is found that the most intense hyperfine components of
two-photon lines benefit from a very small Zeeman splitting.


title:
Classification of quasi-trigonometric solutions of the classical
  Yang-Baxter equation

abstract:
  It was proved by Montaner and Zelmanov that up to classical twisting Lie
bialgebra structures on $\mathfrak{g}[u]$ fall into four classes. Here
$\mathfrak{g}$ is a simple complex finite-dimensional Lie algebra. It turns out
that classical twists within one of these four classes are in a one-to-one
correspondence with the so-called quasi-trigonometric solutions of the
classical Yang-Baxter equation. In this paper we give a complete list of the
quasi-trigonometric solutions in terms of sub-diagrams of the certain Dynkin
diagrams related to $\mathfrak{g}$. We also explain how to quantize the
corresponding Lie bialgebra structures.


title:
The Lagrangian-averaged model for magnetohydrodynamics turbulence and
  the absence of bottleneck

abstract:
  We demonstrate that, for the case of quasi-equipartition between the velocity
and the magnetic field, the Lagrangian-averaged magnetohydrodynamics
alpha-model (LAMHD) reproduces well both the large-scale and small-scale
properties of turbulent flows; in particular, it displays no increased
(super-filter) bottleneck effect with its ensuing enhanced energy spectrum at
the onset of the sub-filter-scales. This is in contrast to the case of the
neutral fluid in which the Lagrangian-averaged Navier-Stokes alpha-model is
somewhat limited in its applications because of the formation of spatial
regions with no internal degrees of freedom and subsequent contamination of
super-filter-scale spectral properties. No such regions are found in LAMHD,
making this method capable of large reductions in required numerical degrees of
freedom; specifically, we find a reduction factor of 200 when compared to a
direct numerical simulation on a large grid of 1536^3 points at the same
Reynolds number.


title:
Resonance Recombination Model and Quark Distribution Functions in the
  Quark-Gluon Plasma

abstract:
  We investigate the consequences of space-momentum correlations in quark
phase-space distributions for coalescence processes at the hadronization
transition. Thus far it has been proved difficult to reconcile such
correlations with the empirically observed constituent quark number scaling
(CQNS) at the Relativistic Heavy-Ion Collider (RHIC). To address this problem
we combine our earlier developed quark recombination model with quark
phase-space distributions computed from relativistic Langevin simulations in an
expanding Quark-Gluon Plasma (QGP). Hadronization is based on resonance
formation within a Boltzmann equation which recovers thermal equilibrium and
obeys energy conservation in the quark-coalescence process, while the fireball
background is adjusted to hydrodynamic simulations of semi-central Au-Au
collisions at RHIC. To facilitate the applicability of the Langevin process, we
focus on strange and charm quarks. Their interactions in the QGP are modeled
using leading-order perturbative QCD augmented by effective Lagrangians with
resonances which smoothly merge into hadronic states formed at T_c. The
interaction strength is adjusted to reproduce the empirical saturation value
for the quark-elliptic flow, v_{2,q}^{sat}~7-8%. The resulting phi and J/\psi
elliptic flow recover CQNS over a large range in transverse momentum (p_T)
within a few percent. As a function of transverse kinetic energy, both the
quark spectra from the Langevin simulations and the meson spectra generated via
resonance recombination recover CQNS from zero to at least 3 GeV.


title:
Local structure of Brill-Noether strata in the moduli space of flat
  stable bundles

abstract:
  We study the Brill-Noether stratification of the coarse moduli space of
locally free stable and flat sheaves of a compact Kahler manifold, proving that
these strata have quadratic algebraic singularities.


title: A Method of Classifying Simple Laced Root Systems

abstract:
  A root system in which all roots have same norm is known as a simply laced
root system. We present a simple method of classifying all simply laced root
systems.


title:
Switching Game of Backward Stochastic Differential Equations and
  Associated System of Obliquely Reflected Backward Stochastic Differential
  Equations

abstract:
  This paper is concerned with the switching game of a one-dimensional backward
stochastic differential equation (BSDE). The associated Bellman-Isaacs equation
is a system of matrix-valued BSDEs living in a special unbounded convex domain
with reflection on the boundary along an oblique direction. In this paper, we
show the existence of an adapted solution to this system of BSDEs with oblique
reflection by the penalization method, the monotone convergence, and the a
priori estimates.


title:
Segmentation of DNA sequences into twostate regions and melting fork
  regions

abstract:
  The accurate prediction and characterization of DNA melting domains by
computational tools could facilitate a broad range of biological applications.
However, no algorithm for melting domain prediction has been available until
now. The main challenges include the difficulty of mathematically mapping a
qualitative description of DNA melting domains to quantitative statistical
mechanics models, as well as the absence of 'gold standards' and a need for
generality. In this paper, we introduce a new approach to identify the twostate
regions and melting fork regions along a given DNA sequence. Compared with an
ad hoc segmentation used in one of our previous studies, the new algorithm is
based on boundary probability profiles, rather than standard melting maps. We
demonstrate that a more detailed characterization of the DNA melting domain map
can be obtained using our new method, and this approach is independent of the
choice of DNA melting model. We expect this work to drive our understanding of
DNA melting domains one step further.


title: Magnetic fields and star formation in spiral galaxies

abstract:
  The main observational results from radio continuum and polarization
observations about the magnetic field strength and large-scale pattern for
face-on and edge-on spiral galaxies are summarized and compared within our
sample of galaxies of different morphological types, inclinations, and star
formation rates (SFR). We found that galaxies with low SFR have higher thermal
fractions/smaller synchrotron fractions than those with normal or high SFR.
Adopting an equipartition model, we conclude that the nonthermal radio emission
and the \emph{total magnetic field} strength grow nonlinearly with SFR, while
the regular magnetic field strength does not seem to depend on SFR. We also
studied the magnetic field structure and disk thicknesses in highly inclined
(edge-on) galaxies. We found in four galaxies that - despite their different
radio appearance - the vertical scale heights for both, the thin and thick
disk/halo, are about equal (0.3/1.8 kpc at 4.75 GHz), independently of their
different SFR. This implies that all these galaxies host a galactic wind, in
which the bulk velocity of the cosmic rays (CR) is determined by the total
field strength within the galactic disk. The galaxies in our sample also show a
similar large-scale magnetic field configuration, parallel to the midplane and
X-shaped further away from the disk plane, independent of Hubble type and SFR
in the disk. Hence we conclude that also the large-scale magnetic field pattern
does not depend on the amount of SFR.


title: Singularities in geodesic surface congruence

abstract:
  In the stringy cosmology, we investigate singularities in geodesic surface
congruences for the time-like and null strings to yield the Raychaudhuri type
equations possessing correction terms associated with the novel features owing
to the strings. Assuming the stringy strong energy condition, we have a
Hawking-Penrose type inequality equation. If the initial expansion is negative
so that the congruence is converging, we show that the expansion must pass
through the singularity within a proper time. We observe that the stringy
strong energy conditions of both the time-like and null string congruences
produce the same inequality equation.


title: Casimir interaction with an 1/r-dependence

abstract:
  We show that in theory it is possible to obtain a Casimir interaction
potential that varies with distance as 1/r. We achieve this by invoking
hypothetical particles having a harmonic oscillator interaction potential. The
derivation parallels the derivation of the Casimir-Polder interaction between
atoms in electromagnetism.


title:
First measurements of the total and partial stellar cross section to the
  $s$-process branching-point $^{79}$Se

abstract:
  Although $^{79}$Se represents an important branching in the weak s process,
the stellar neutron capture cross sections to this isotope have not yet been
measured experimentally. In this case, experimental data is essential for
evaluating the important branching in the s-process reaction path at $^{79}$Se.
The total cross section of $^{78}$Se at a stellar energy of kT = 25 keV has
been investigated with a combination of the activation technique and
accelerator mass spectrometry (AMS), since offline decay counting is
prohibitive due to the long terrestrial half life of $^{79}$Se (2.80$\pm$0.36
$\times10^5$ y) as well as the absence of suitable $\gamma$-ray transitions.
The preliminary result for the total Maxwellian averaged cross section is
$<\sigma>_{30 keV}$= 60.1$\pm$9.6 mbarn, significantly lower than the previous
recommended value. In a second measurement, also the partial cross section to
the 3.92 min-isomer was determined via $\gamma$-spectroscopy and yielded
$<\sigma>_{30 keV}$(part.)= 42.0$\pm$2.0 mbarn.


title: Perturbativity and a Fourth Generation in the MSSM

abstract:
  We study an extension of the MSSM with a fourth generation of chiral matter.
With this extension no value of $\tb$ allows the theory to stay perturbative up
to the GUT scale. We suggest one model with extra vector-like states at the TeV
scale that allows perturbativity all the way up to the GUT scale.


title: Flat galaxies with dark matter halos - existence and stability

abstract:
  We consider a model for a flat, disk-like galaxy surrounded by a halo of dark
matter, namely a Vlasov-Poisson type system with two particle species, the
stars which are restricted to the galactic plane and the dark matter particles.
These constituents interact only through the gravitational potential which
stars and dark matter create collectively. Using a variational approach we
prove the existence of steady state solutions and their nonlinear stability
under suitably restricted perturbations.


title: Semiclassical spectral correlator in quasi one-dimensional systems

abstract:
  We investigate the spectral statistics of chaotic quasi one dimensional
systems such as long wires. To do so we represent the spectral correlation
function $R(\epsilon)$ through derivatives of a generating function and
semiclassically approximate the latter in terms of periodic orbits. In contrast
to previous work we obtain both non-oscillatory and oscillatory contributions
to the correlation function. Both types of contributions are evaluated to
leading order in $1/\epsilon$ for systems with and without time-reversal
invariance. Our results agree with expressions from the theory of disordered
systems.


title: Casimir forces between nano-structured particles

abstract:
  We develop a computational study of Casimir forces between three dimensional
(3D) finite objects with an internal granular structure. The objects in the
model consist of a finite arrangement of nanometer sized spherical particles
having a dipolar interaction. In this model system one can both study the basic
properties of the Casimir forces, and the effects from changing the parameters
of the nano-structured materials that constitute the particles; this last type
of study leads to a form of control of the Casimir force and an insight into
possible technological applications. We present examples of both kinds of
study.


title: A simple, polynomial-time algorithm for the matrix torsion problem

abstract:
  The Matrix Torsion Problem (MTP) is: given a square matrix M with rational
entries, decide whether two distinct powers of M are equal. It has been shown
by Cassaigne and the author that the MTP reduces to the Matrix Power Problem
(MPP) in polynomial time: given two square matrices A and B with rational
entries, the MTP is to decide whether B is a power of A. Since the MPP is
decidable in polynomial time, it is also the case of the MTP. However, the
algorithm for MPP is highly non-trivial. The aim of this note is to present a
simple, direct, polynomial-time algorithm for the MTP.


title: The information capacity of hypercycles

abstract:
  Hypercycles are information integration systems which are thought to overcome
the information crisis of prebiotic evolution by ensuring the coexistence of
several short templates. For imperfect template replication, we derive a simple
expression for the maximum number of distinct templates $n_m$ that can coexist
in a hypercycle and show that it is a decreasing function of the length $L$ of
the templates. In the case of high replication accuracy we find that the
product $n_m L$ tends to a constant value, limiting thus the information
content of the hypercycle. Template coexistence is achieved either as a
stationary equilibrium (stable fixed point) or a stable periodic orbit in which
the total concentration of functional templates is nonzero. For the hypercycle
system studied here we find numerical evidence that the existence of an
unstable fixed point is a necessary condition for the presence of periodic
orbits.


title: Recent Efforts in Data Compilations for Nuclear Astrophysics

abstract:
  Some recent efforts in compiling data for astrophysical purposes are
introduced, which were discussed during a JINA-CARINA Collaboration meeting on
"Nuclear Physics Data Compilation for Nucleosynthesis Modeling" held at the
ECT* in Trento/ Italy from May 29th- June 3rd, 2007. The main goal of this
collaboration is to develop an updated and unified nuclear reaction database
for modeling a wide variety of stellar nucleosynthesis scenarios. Presently a
large number of different reaction libraries (REACLIB) are used by the
astrophysics community. The "JINA Reaclib Database" on
http://www.nscl.msu.edu/\~nero/db/ aims to merge and fit the latest
experimental stellar cross sections and reaction rate data of various
compilations, e.g. NACRE and its extension for Big Bang nucleosynthesis,
Caughlan and Fowler, Iliadis et al., and KADoNiS. The KADoNiS (Karlsruhe
Astrophysical Database of Nucleosynthesis in Stars,
http://nuclear-astrophysics.fzk.de/kadonis) project is an online database for
neutron capture cross sections relevant to the s process. The present version
v0.2 is already included in a REACLIB file from Basel university
(http://download.nucastro.org/astro/reaclib). The present status of
experimental stellar $(n,\gamma)$ cross sections in KADoNiS is shown. A "high
priority list" for measurements and evaluations for light charged-particle
reactions set up by the JINA-CARINA collaboration is presented. The central web
access point to submit and evaluate new data is provided by the Oak Ridge group
via the http://www.nucastrodata.org homepage. "Workflow tools" aim to make the
evaluation process transparent and allow users to follow the progress.


title:
On the distance between separatrices for the discretized pendulum
  equation

abstract:
  We consider the discretization
  q(t+\epsilon)+q(t-\epsilon)-2q(t)=\epsilon^{2}\sin\big(q(t)\big),
  $\epsilon>0$ a small parameter, of the pendulum equation $ q '' = \sin (q) $;
in system form, we have the discretization
  q(t+\epsilon)-q(t)=\epsilon p(t+\epsilon),
p(t+\epsilon)-p(t)=\epsilon\sin\big(q(t)\big).
  of the system
  q'=p, p'=\sin(q).
  The latter system of ordinary differential equations has two saddle points at
$A=(0,0)$, $B=(2\pi, 0)$ and near both, there exist stable and unstable
manifolds. It also admits a heteroclinic orbit connecting the stationary points
$B$ and $A$ parametrised by $q_0(t)=4\arctan\big(e^{-t}\big)$ and which
contains the stable manifold of this system at $A$ as well as its unstable
manifold at $B$. We prove that the stable manifold of the point $A$ and the
unstable manifold of the point $B$ do not coincide for the discretization. More
precisely, we show that the vertical distance between these two manifolds is
exponentially small but not zero and in particular we give an asymptotic
estimate of this distance. For this purpose we use a method adapted from the
article of Sch\"afke-Volkmer \cite{SV} using formal series and accurate
estimates of the coefficients. Our result is similar to that of Lazutkin et.
al. \cite{LS}; our method of proof, however, is quite different.


title:
Gravo-thermodynamics of the Intracluster Medium: negative heat capacity
  and dilation of cooling time scales

abstract:
  The time scale for cooling of the gravitationally bound gaseous intracluster
medium (ICM) is not determined by radiative processes alone. If the ICM is in
quasi-hydrostatic equilibrium in the fixed gravitational field of the dark
matter halo then energy losses incurred by the gravitational potential energy
of the gas should also be taken into account. This "gravitational heating" has
been known for a while using explicit solutions to the equations of motion.
Here, we re-visit this effect by applying the virial theorem to gas in
quasi-hydrostatic equilibrium in an external gravitational field, neglecting
the gravity of the gas. For a standard NFW form of halo profiles and for a
finite gas density, the response of the gas temperature to changes in the total
energy is significantly delayed. The effective cooling time could be prolonged
by more than an order of magnitude inside the scale radius ($\rs$) of the halo.
Gas lying at a distance twice the scale radius, has negative heat capacity so
that the temperature increases as a result of energy losses. Although external
heating (e.g. by AGN activity) is still required to explain the lack of cool
ICM near the center, the analysis here may circumvent the need for heating in
farther out regions where the effective cooling time could be prolonged to
become larger than the cluster age and also explains the increase of
temperature with radius in these regions.


title: Values of the t-invariant for small Seifert manifolds

abstract:
  The t-invariant can be considered as the Turaev-Viro invariant of order 5
computed for integer colors only. We compute all values of the t-invariant for
Seifert manifolds with base sphere and three singular fibers. As a result we
show that the manifolds parameters modulo five define the value of the
t-invariant. Partially we show that there are 12 distinct values of the
t-invariant for these manifolds. Some examples show that the t-invariant for
these manifolds is not defined by the first homology group.


title: Periodic Graphs

abstract:
  Let $X$ be a graph on $n$ vertices with with adjacency matrix $A$ and let
$H(t)$ denote the matrix-valued function $\exp(iAt)$. If $u$ and $v$ are
distinct vertices in $X$, we say perfect state transfer}from $u$ to $v$ occurs
if there is a time $\tau$ such that $|H(\tau)_{u,v}|=1$. If $u\in V(X)$ and
there is a time $\sg$ such that $|H(\sg)_{u,u}|=1$, we say $X$ is periodic at
$u$ with period $\sg$. We show that if perfect state transfer from $u$ to $v$
occurs at time $\tau$, then $X$ is periodic at both $u$ and $v$ with period
$2\tau$. We extend previous work by showing that a regular graph with at least
four distinct eigenvalues is periodic with respect to some vertex if and only
if its eigenvalues are integers. We show that, for a class of graphs $X$
including all vertex-transitive graphs, if perfect state transfer occurs at
time $\tau$, then $H(\tau)$ is a scalar multiple of a permutation matrix of
order two with no fixed points. Using certain Hadamard matrices, we construct a
new infinite family of graphs on which perfect state transfer occurs.


title: A note on the span of Hadamard products of vectors

abstract:
  We give a new proof of Theorem 6 in [L. Qiu and X. Zhan, On the span of
Hadamard products of vectors, Linear Algebra Appl. 422 (2007) 304--307].


title:
New Stellar $(n,\gamma)$ Cross Sections and The "Karlsruhe Astrophysical
  Database of Nucleosynthesis in Stars"

abstract:
  Since April 2005 a regularly updated stellar neutron cross section
compilation is available online at http://nuclear-astrophysics.fzk.de/kadonis.
This online-database is called the "Karlsruhe Astrophysical Database of
Nucleosynthesis in Stars" project and is based on the previous Bao et al.
compilation from the year 2000. The present version \textsc{KADoNiS} v0.2
(January 2007) includes recommended cross sections for 280 isotopes between
$^{1}$H and $^{210}$Po and 75 semi-empirical estimates for isotopes without
experimental information. Concerning stellar $(n,\gamma)$ cross sections of the
32 stable, proton-rich isotopes produced by the $p$ process experimental
information is only available for 20 isotopes, but 9 of them have rather large
uncertainties of $\geq$9%. The first part of a systematic study of stellar
$(n,\gamma)$ cross sections of the $p$-process isotopes $^{74}$Se, $^{84}$Sr,
$^{102}$Pd, $^{120}$Te, $^{130}$Ba, $^{132}$Ba, $^{156}$Dy, and $^{174}$Hf is
presented. In another application \textsc{KADoNiS} v0.2 was used for an
modification of a reaction library of Basel university. With this modified
library $p$-process network calculations were carried out and compared to
previous results.


title: Vortex dynamics in trapped Bose-Einstein condensate

abstract:
  We perform numerical simulations of vortex motion in a trapped Bose-Einstein
condensate by solving the two-dimensional Gross-Pitaevskii Equation in the
presence of a simple phenomenological model of interaction between the
condensate and the finite temperature thermal cloud. At zero temperature, the
trajectories of a single, off - centred vortex precessing in the condensate,
and of a vortex - antivortex pair orbiting within the trap, excite acoustic
emission. At finite temperatures the vortices move to the edge of the
condensate and vanish. By fitting the finite -temperature trajectories, we
relate the phenomenological damping parameter to the friction coefficients
$\alpha$ and $\alpha^{'}$, which are used to describe the interaction between
quantised vortices and the normal fluid in superfluid helium.


title: Distinguishing Primitive Permutation Groups

abstract:
  Let $G$ be a permutation group acting on a set $V$. A partition $\pi$ of $V$
is distinguishing if the only element of $G$ that fixes each cell of $\pi$ is
the identity. The distinguishing number of $G$ is the minimum number of cells
in a distinguishing partition. We prove that if $G$ is a primitive permutation
group and $|V|\ge336$, its distinguishing number is two.


title:
Shape transitions in neutron-rich Yb, Hf, W, Os, and Pt isotopes within
  a Skyrme Hartree-Fock + BCS approach

abstract:
  Self-consistent axially symmetric Skyrme Hartree-Fock plus BCS calculations
are performed to study the evolution of shapes with the number of nucleons in
various chains of Yb, Hf, W, Os, and Pt isotopes from neutron number N=110 up
to N=122. Potential energy curves are analyzed in a search for signatures of
oblate-prolate phase shape transitions and results from various Skyrme and
pairing forces are considered. Comparisons with results obtained with the Gogny
interaction as well as with relativistic mean field calculations are presented.
The role of the $\gamma$ degree of freedom is also discussed.


title:
$C^{1+\alpha}$-Regularity for Two-Dimensional Almost-Minimal Sets in
  $\R^n$

abstract:
  We give a new proof and a partial generalization of Jean Taylor's result [Ta]
that says that Almgren almost-minimal sets of dimension 2 in $\R^3$ are locally
$C^{1+\alpha}$-equivalent to minimal cones. The proof is rather elementary, but
uses a local separation result proved in [D3] and an extension of Reifenberg's
parameterization theorem [DDT]. The key idea is still that if $X$ is the cone
over an arc of small Lipschitz graph in the unit sphere, but $X$ is not
contained in a disk, we can use the graph of a harmonic function to deform $X$
and diminish substantially its area. The local separation result is used to
reduce to unions of cones over arcs of Lipschitz graphs. A good part of the
proof extends to minimal sets of dimension 2 in $\R^n$, but in this setting our
final regularity result on $E$ may depend on the list of minimal cones obtained
as blow-up limits of $E$ at a point.


title:
Critical behavior of the compact 3d U(1) theory in the limit of zero
  spatial coupling

abstract:
  Critical properties of the compact three-dimensional U(1) lattice gauge
theory are explored at finite temperatures on an asymmetric lattice. For
vanishing value of the spatial gauge coupling one obtains an effective
two-dimensional spin model which describes the interaction between Polyakov
loops. We study numerically the effective spin model for N_t=1,4,8 on lattices
with spatial extension ranging from L=64 to L=256. Our results indicate that
the finite-temperature U(1) lattice gauge theory belongs to the universality
class of the two-dimensional XY model, thus supporting the Svetitsky-Yaffe
conjecture.


title:
Synchronization and Information Transmission in Spatio-Temporal Networks
  of Deformable Units

abstract:
  We study the relationship between synchronization and the rate with which
information is exchanged between nodes in a spatio-temporal network that
describes the dynamics of classical particles under a substrate
Remoissenet-Peyrard potential. We also show how phase and complete
synchronization can be detected in this network. The difficulty in detecting
phase synchronization in such a network appears due to the highly non-coherent
character of the particle dynamics which unables a proper definition of the
phase dynamics. The difficulty in detecting complete synchronization appears
due to the spatio character of the potential which results in an asymptotic
state highly dependent on the initial state.


title: Bound Excitons in Sr$_{2}$CuO$_{3}$

abstract:
  We investigated temperature dependent optical spectra of the one-dimensional
chain compound Sr$_{2}$CuO$_{3}$. The charge transfer transition polarized
along the chain direction shows a strongly asymmetric line shape as expected in
one-dimensional extended Hubbard model. At low temperature the charge transfer
peak shows a large blue shift and reveals additional sharp peaks at the gap.
Even though many spectroscopic studies suggest that this material can not have
a bound exciton based on the one-dimensional extended Hubbard model, we
attribute the additional sharp peaks to excitons, which come to exist due to
the long range Coulomb interaction.


title:
On the existence of compactly supported reconstruction functions in a
  sampling problem

abstract:
  Assume that samples of a filtered version of a function in a shift-invariant
space are avalaible. This work deals with the existence of a sampling formula
involving these samples and having reconstruction functions with compact
support. Thus, low computational complexity is involved and truncation errors
are avoided. This is done in the light of the generalized sampling theory by
using the oversampling technique: more samples than strictly necessary are
used. For a suitable choice of the sampling period, a necessary and sufficient
condition is given in terms of the Kronecker canonical form of a matrix pencil.
Comparing with other characterizations in the mathematical literature, the
given here has an important advantage: it can be reliable computed by using the
GUPTRI form of the matrix pencil. Finally, a practical method for computing the
compactly supported reconstruction functions is given for the important case
where the oversampling rate is minimum.


title:
Mach's Principle: Exact Frame-Dragging by Energy Currents in the
  Universe

abstract:
  We show that the dragging of axis directions of local inertial frames by a
weighted average of the energy currents in the universe (Mach's principle) is
exact for all linear perturbations of all Friedmann-Robertson-Walker universes
and for all types of matter.


title: Closure properties of solutions to heat inequalities

abstract:
  We prove that if $u_1,u_2 : (0,\infty) \times \R^d \to (0,\infty)$ are
sufficiently well-behaved solutions to certain heat inequalities on $\R^d$ then
the function $u: (0,\infty) \times \R^d \to (0,\infty)$ given by
$u^{1/p}=u_1^{1/p_1} * u_2^{1/p_2}$ also satisfies a heat inequality of a
similar type provided $\tfrac{1}{p_1} + \tfrac{1}{p_2} = 1 + \tfrac{1}{p}$. On
iterating, this result leads to an analogous statement concerning $n$-fold
convolutions. As a corollary, we give a direct heat-flow proof of the sharp
$n$-fold Young convolution inequality and its reverse form.


title:
Probing the low-x structure of nuclear matter with diffractive hadron
  production in pA collisions

abstract:
  We argue that hadron production in coherent diffraction of proton on a heavy
nucleus provides a very sensitive probe of the low-x QCD dynamics. This process
probes the BFKL dynamics in proton and the non-linear gluon evolution in
nucleus. We calculate the diffractive hadron production cross sections in the
RHIC and LHC kinematic regions. To study the nuclear effects we introduce the
diffractive nuclear modification factor. We show that unlike the nuclear
modification factor for inclusive hadron production that has a very interesting
dynamics at RHIC but is expected to be almost completely saturated at the LHC,
the nuclear modification factor for diffractive production exhibits a
non-trivial behavior both at RHIC and LHC.


title: Factorizations of EP operators

abstract:
  In this paper we characterize EP operators through the existence of different
types of factorizations. Our results extend to EP operators existing
characterizations for EP matrices and give new characterizations both for EP
matrices and EP operators.


title: Tools for working with multiplier Hopf algebras

abstract:
  Let $(A,\Delta)$ be a multiplier Hopf algebra. In general, the underlying
algebra $A$ need not have an identity and the coproduct $\Delta$ does not map
$A$ into $A\otimes A$ but rather into its multiplier algebra $M(A\otimes A)$.
In this paper, we study {\it some tools} that are frequently used when dealing
with such multiplier Hopf algebras and that are typical for working with
algebras without identity in this context.
  The {\it basic ingredient} is a unital left $A$-module $X$. And the basic
construction is that of extending the module by looking at linear maps
$\rho:A\to X$ satisfying $\rho(aa')=a\rho(a')$ where $a,a'\in A$. We write the
module action as multiplication. Of course, when $x\in X$, and when
$\rho(a)=ax$, we get such a linear map. And if $A$ has an identity, all linear
maps $\rho$ have this form for $x=\rho(1)$. However, the point is that in the
case of a non-unital algebra, the space of such maps is in general strictly
bigger than $X$ itself. We get an {\it extended module}, denoted by $\bar X$
(for reasons that will be explained in the paper).
  We study all sorts of more complicated situations where such extended modules
occur and we illustrate all of this with {\it several examples}, from very
simple ones to more complex ones where iterated extensions come into play. We
refer to cases that appear in the literature.
  We use this basic idea of extending modules to explain, in a more rigorous
way, the so-called {\it covering technique}, which is needed when using {\it
Sweedler notations} for coproducts and coactions. Again, we give many examples
and refer to the existing literature where this technique is applied.


title: Finding the theta-Guarded Region

abstract:
  We are given a finite set of n points (guards) G in the plane R^2 and an
angle 0 < theta < 2 pi. A theta-cone is a cone with apex angle theta. We call a
theta-cone empty (with respect to G) if it does not contain any point of G. A
point p in R^2 is called theta-guarded if every theta-cone with its apex
located at p is non-empty. Furthermore, the set of all theta-guarded points is
called the theta-guarded region, or the theta-region for short.
  We present several results on this topic. The main contribution of our work
is to describe the theta-region with O(n/theta) circular arcs, and we give an
algorithm to compute it. We prove a tight O(n) worst-case bound on the
complexity of the theta-region for theta >= pi/2. In case theta is bounded from
below by a positive constant, we prove an almost linear bound O(n^(1+epsilon))
for any epsilon > 0 on the complexity. Moreover, we show that there is a
sequence of inputs such that the asymptotic bound on the complexity of their
theta-region is Omega(n^2). In addition we point out gaps in the proofs of a
recent publication that claims an O(n) bound on the complexity for any constant
angle theta.


title:
The quantum equivariant cohomology of toric manifolds through mirror
  symmetry

abstract:
  Using mirror symmetry as described by Hori and Vafa, we compute the quantum
equivariant cohomology ring of toric manifolds. This ring arises naturally in
topological gauged sigma-models and is related to the Hamiltonian Gromov-Witten
invariants of the target manifold.


title:
The Limiting Distributions of the Coefficients of the q-Derangement
  Numbers

abstract:
  We show that the distribution of the coefficients of the q-derangement
numbers is asymptotically normal. We also show that this property holds for the
q-derangement numbers of type B.


title: Detuning effects in the vertical cold-atom micromaser

abstract:
  The quantum theory of the cold atom micromaser including the effects of
gravity is established in the general case where the cavity mode and the atomic
transition frequencies are detuned. We show that atoms which classically would
not reach the interaction region are able to emit a photon inside the cavity.
The system turns out to be extremely sensitive to the detuning and in
particular to its sign. A method to solve the equations of motion for non
resonant atom-field interaction and arbitrary cavity modes is presented.


title: Gluon polarization and higher twist effects

abstract:
  We examine the influence of the recent CLAS and COMPASS experiments on our
understanding of higher twist (HT) effects and the gluon polarization, and show
how EIC could discriminate between negative and positive gluon polarizations.
We comment on the issue of HT and the recent DSSV analysis.


title: Anomalous dimension with wrapping at four loops in N=4 SYM

abstract:
  In this paper we give all the details of the calculation that we presented in
our previous paper arXiv:0712.3522, concerning the four-loop anomalous
dimension of the Konishi descendant tr(\phi Z\phi Z-\phi \phi Z Z) in the SU(2)
sector of the N=4 planar SYM theory. We explicitly consider all the wrapping
diagrams that we compute using an N=1 superspace approach and Gegenbauer
polynomial x-space techniques.


title: Geometry of antimatroidal point sets

abstract:
  The notion of "antimatroid with repetition" was conceived by Bjorner, Lovasz
and Shor in 1991 as a multiset extension of the notion of antimatroid. When the
underlying set consists of only two elements, such two-dimensional antimatroids
correspond to point sets in the plane. In this research we concentrate on
geometrical properties of antimatroidal point sets in the plane and prove that
these sets are exactly parallelogram polyominoes. Our results imply that
two-dimensional antimatroids have convex dimension 2. The second part of the
research is devoted to geometrical properties of three-dimensional antimatroids
closed under intersection.


title:
A solenoidal electron spectrometer for a precision measurement of the
  neutron $\beta$-asymmetry with ultracold neutrons

abstract:
  We describe an electron spectrometer designed for a precision measurement of
the neutron $\beta$-asymmetry with spin-polarized ultracold neutrons. The
spectrometer consists of a 1.0-Tesla solenoidal field with two identical
multiwire proportional chamber and plastic scintillator electron detector
packages situated within 0.6-Tesla field-expansion regions. Select results from
performance studies of the spectrometer with calibration sources are reported.


title:
Rotational spectroscopy of isotopic vinyl cyanide,
  H$_2$C=CH$-$C$\equiv$N, in the laboratory and in space

abstract:
  The rotational spectra of singly substituted $^{13}$C and $^{15}$N isotopic
species of vinyl cyanide have been studied in natural abundances between 64 and
351 GHz. In combination with previous results, greatly improved spectroscopic
parameters have been obtained which in turn helped to identify transitions of
the $^{13}$C species for the first time in space through a molecular line
survey of the extremely line-rich interstellar source Sagittarius B2(N) in the
3 mm region with some additional observations at 2 mm. The $^{13}$C species are
detected in two compact ($\sim 2.3''$), hot (170 K) cores with a column density
of $\sim 3.8 \times 10^{16}$ and $1.1 \times 10^{16}$ cm$^{-2}$, respectively.
In the main source, the so-called ``Large Molecule Heimat'', we derive an
abundance of $2.9 \times 10^{-9}$ for each $^{13}$C species relative to H$_2$.
An isotopic ratio $^{12}$C/$^{13}$C of 21 has been measured. Based on a
comparison to the column densities measured for the $^{13}$C species of ethyl
cyanide also detected in this survey, it is suggested that the two hot cores of
Sgr B2(N) are in different evolutionary stages. Supplementary laboratory data
for the main isotopic species recorded between 92 and 342 GHz permitted an
improvement of its spectroscopic parameters as well.


title: Metabolic scaling law for fetus and placenta

abstract: We present a version of Kleiber's scaling law for fetus and placenta.


title:
A study of the (m,d,N)=(1,3,2) Lifshitz point and of the three-
  dimensional XY universality class by high-temperature bivariate series for
  the XY models with anisotropic competing interactions

abstract:
  High-temperature bivariate expansions have been derived for the two-spin
correlation-function in a variety of classical lattice XY (planar rotator)
models in which spatially isotropic interactions among first-neighbor spins
compete with spatially isotropic or anisotropic (in particular uniaxial)
interactions among next-to-nearest-neighbor spins. The expansions, calculated
for cubic lattices of dimension d=1,2 and 3, are expressed in terms of the two
variables K1=J1/kT and K2=J2/kT, where J1 and J2 are the nearest-neighbor and
the next-to-nearest-neighbor exchange couplings, respectively. This report
deals in particular with the properties of the d=3 uniaxial XY model (ANNNXY
model) for which the bivariate expansions have been computed through the 18-th
order, thus extending by 12 orders the results so far available and making a
study of this model possible over a wide range of values of the competition
parameter R=J2/J1.


title: Locally Decodable Quantum Codes

abstract:
  We study a quantum analogue of locally decodable error-correcting codes. A
q-query locally decodable quantum code encodes n classical bits in an m-qubit
state, in such a way that each of the encoded bits can be recovered with high
probability by a measurement on at most q qubits of the quantum code, even if a
constant fraction of its qubits have been corrupted adversarially. We show that
such a quantum code can be transformed into a classical q-query locally
decodable code of the same length that can be decoded well on average (albeit
with smaller success probability and noise-tolerance). This shows, roughly
speaking, that q-query quantum codes are not significantly better than q-query
classical codes, at least for constant or small q.


title:
Combating entanglement sudden death with non-local quantum-error
  correction

abstract:
  We study the possibility of preventing finite-time disentanglement caused by
dissipation by making use of "non-local quantum error correction. This is made
in comparison of previous results, where was shown that "local" quantum error
correction can delay disentanglement, but can also cause entanglement sudden
death when is not originally present.


title: Finite-size effects in the superconformal beta-deformed N=4 SYM

abstract:
  We study finite size effects for composite operators in the SU(2) sector of
the superconformal beta-deformed N=4 SYM theory. In particular we concentrate
on the spectrum of one single magnon. Since in this theory one-impurity states
are non BPS we compute their anomalous dimensions including wrapping
contributions up to four loops and discuss higher order effects.


title:
Doping Dependence of Superconductivity and Lattice Constants in Hole
  Doped $La_{1-x}Sr_xFeAsO$

abstract:
  By using solid state reaction method we have fabricated the hole doped
$La_{1-x}Sr_xFeAsO$ superconductors with Sr content up to 0.13. It is found
that the sharp anomaly at about 150 K and the low temperature upturn of
resistivity are suppressed by doping holes into the parent phase. Interestingly
both the superconducting transition temperature $T_c$ and the lattice constants
(a-axis and c-axis) increase monotonously with hole concentration, in sharp
contrast with the electron doped side where the $T_c$ increases with a
continuing shrinkage of the lattice constants either by dope more fluorine or
oxygen vacancies into the system. Our data clearly illustrate that the
superconductivity can be induced by doping holes via substituting the trivalent
La with divalent Sr in the LaFeAsO system with single FeAs layer, and the $T_c$
in the present system exhibits a symmetric behavior at the electron and hole
doped sides, as we reported previously.


title: A trajectory-based understanding of quantum interference

abstract:
  Interference is one of the most fundamental features which characterizes
quantum systems. Here we provide an exhaustive analysis of the interfere
dynamics associated with wave-packet superpositions from both the standard
quantum-mechanical perspective and the Bohmian one.
  From this analysis, clear and insightful pictures of the physics involved in
this kind of processes are obtained, which are of general validity (i.e.,
regardless of the type of wave packets considered) in the understanding of more
complex cases where interference is crucial (e.g., scattering problems, slit
diffraction, quantum control scenarios or, even, multipartite interactions). In
particular, we show how problems involving wave-packet interference can be
mapped onto problems of wave packets scattered off potential barriers.


title:
Diversity-induced resonance in a system of globally coupled linear
  oscillators

abstract:
  The purpose of this paper to analyze in some detail the arguably simplest
case of diversity-induced reseonance: that of a system of globally-coupled
linear oscillators subjected to a periodic forcing. Diversity appears as the
parameters characterizing each oscillator, namely its mass, internal frequency
and damping coefficient are drawn from a probability distribution. The main
ingredients for the diversity-induced-resonance phenomenon are present in this
system as the oscillators display a variability in the individual responses but
are induced, by the coupling, to synchronize their responses. A steady state
solution for this model is obtained. We also determine the conditions under
which it is possible to find a resonance effect.


title:
Log canonical thresholds of smooth Fano threefolds. With an appendix by
  Jean-Pierre Demailly

abstract: We compute global log canonical thresholds of some smooth Fano threefolds.


title:
How Xenopus laevis embryos replicate reliably: investigating the
  random-completion problem

abstract:
  DNA synthesis in \textit{Xenopus} frog embryos initiates stochastically in
time at many sites (origins) along the chromosome. Stochastic initiation
implies fluctuations in the time to complete and may lead to cell death if
replication takes longer than the cell cycle time ($\approx 25$ min).
Surprisingly, although the typical replication time is about 20 min, \textit{in
vivo} experiments show that replication fails to complete only about 1 in 300
times. How is replication timing accurately controlled despite the
stochasticity? Biologists have proposed two solutions to this
"random-completion problem." The first solution uses randomly located origins
but increases their rate of initiation as S phase proceeds, while the second
uses regularly spaced origins. In this paper, we investigate the
random-completion problem using a type of model first developed to describe the
kinetics of first-order phase transitions. Using methods from the field of
extreme-value statistics, we derive the distribution of replication-completion
times for a finite genome. We then argue that the biologists' first solution to
the problem is not only consistent with experiment but also nearly optimizes
the use of replicative proteins. We also show that spatial regularity in origin
placement does not alter significantly the distribution of replication times
and, thus, is not needed for the control of replication timing.


title: Moving vortex matter with coexisting vortices and anti-vortices

abstract:
  Moving vortex matter, driven by transport currents independent of time, in
which vortices and anti-vortices coexist is investigated theoretically in thin
superconducting films with nanostructured defects. A simple London model is
proposed for the vortex dynamics in films with periodic arrays of nanomagnets
or cylindrical holes (antidots). Common to these films is that vortex
anti-vortex pairs may be created in the vicinity of the defects by relatively
small transport currents, because it adds to the current generated by the
defects - the nanomagnets screening current, or the antidots backflow current -
and may exceed locally the critical value for vortex anti-vortex pair creation.
The model assumes that vortex matter dynamics is governed by Langevin
equations, modified to account for creation and annihilation of vortex
anti-vortex pairs. For pair creation, it is assumed that whenever the total
current at some location exceeds a critical value, equal to that needed to
separate a vortex from an anti-vortex by a vortex core diameter, a pair is
created instantaneously around this location. Pair annihilation occurs by
vortex anti-vortex collisions. The model is applied to films at zero external
magnetic field and low temperatures. It is found that several moving vortex
matter steady-states with equal numbers of vortices and anti-vortices are
possible.


title: The Mock LISA Data Challenges: from Challenge 1B to Challenge 3

abstract:
  The Mock LISA Data Challenges are a programme to demonstrate and encourage
the development of LISA data-analysis capabilities, tools and techniques. At
the time of this workshop, three rounds of challenges had been completed, and
the next was about to start. In this article we provide a critical analysis of
entries to the latest completed round, Challenge 1B. The entries confirm the
consolidation of a range of data-analysis techniques for Galactic and
massive--black-hole binaries, and they include the first convincing examples of
detection and parameter estimation of extreme--mass-ratio inspiral sources. In
this article we also introduce the next round, Challenge 3. Its data sets
feature more realistic waveform models (e.g., Galactic binaries may now chirp,
and massive--black-hole binaries may precess due to spin interactions), as well
as new source classes (bursts from cosmic strings, isotropic stochastic
backgrounds) and more complicated nonsymmetric instrument noise.


title:
Quantitative Calculations for Black Hole Production at the Large Hadron
  Collider

abstract:
  The framework of Large Extra Dimensions provides a way to explain why gravity
is weaker compared to the other forces in nature. A consequence of this model
is the possible production of D-dimensional Black Holes in high energy p-p
collisions at the Large Hadron Collider. The present work uses the CATFISH
Black Hole generator to study quantitatively how these events could be observed
in the hadronic channel at mid-rapidity using a particle tracking detector.


title:
Precision Measurement of B(D+ -> mu+ nu) and the Pseudoscalar Decay
  Constant fD+

abstract:
  We measure the branching ratio of the purely leptonic decay of the D+ meson
with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 +/-
0.09)x10^(-4), using 818/pb of data taken on the psi(3770) resonance with the
CLEO-c detector at the CESR collider. We use this determination to derive a
value for the pseudoscalar decay constant fD+, combining with measurements of
the D+ lifetime and assuming |Vcd| = |Vus|. We find fD+ = (205.8 +/- 8.5 +/-
2.5) MeV. The decay rate asymmetry [B(D+ -> mu+ nu)-B(D- -> mu- nu)]/[B(D+ ->
mu+ nu)+B(D- -> mu- nu)] = 0.08 +/- 0.08, consistent with no CP violation. We
also set 90% confidence level upper limits on B(D+ -> tau+ nu) < 1.2x10^(-3)
and B(D+ -> e+ nu) < 8.8x10^(-6).


title: The index of a vector field on an orbifold with boundary

abstract:
  A Poincar\'{e}-Hopf theorem in the spirit of Pugh is proven for compact
orbifolds with boundary. The theorem relates the index sum of a smooth vector
field in generic contact with the boundary orbifold to the Euler-Satake
characteristic of the orbifold and a boundary term. The boundary term is
expressed as a sum of Euler characteristics of tangency and exit-region
orbifolds. As a corollary, we express the index sum of the vector field induced
on the inertia orbifold to the Euler characteristics of the associated
underlying topological spaces.


title: On the excedance sets of colored permutations

abstract:
  We define the excedence set and the excedance word on $G_{r,n}$, generalizing
a work of Ehrenborg and Steingrimsson and use the inclusion-exclusion principle
to calculate the number of colored permutations having a prescribed excedance
word. We show some symmetric properties as Log concavity and unimodality of a
specific sequence of excedance words.


title:
The Interaction of an 180 degree Ferroelectric Domain Wall with a Biased
  Scanning Probe Microscopy Tip: Effective Wall Geometry and Thermodynamics in
  Ginzburg-Landau-Devonshire Theory

abstract:
  The interaction of ferroelectric 180 degree domain wall with a strongly
inhomogeneous electric field of biased Scanning Probe Microscope tip is
analyzed within continuous Landau-Ginzburg-Devonshire theory. Equilibrium shape
of the initially flat domain wall boundary bends, attracts or repulses from the
probe apex, depending on the sign and value of the applied bias. For large
tip-wall separations, the probe-induced domain nucleation is possible. The
approximate analytical expressions for the polarization distribution are
derived using direct variational method. The expressions provide insight how
the equilibrium polarization distribution depends on the wall finite-width,
correlation and depolarization effects, electrostatic potential distribution of
the probe and ferroelectric material parameters.


title: Toward a solution of the coincidence problem

abstract:
  The coincidence problem of late cosmic acceleration constitutes a serious
riddle with regard to our understanding of the evolution of the Universe. Here
we argue that this problem may someday be solved -or better understood- by
expressing the Hubble expansion rate as a function of the ratio of densities
(dark matter/dark energy) and observationally determining the said rate in
terms of the redshift.


title: Is Confinement a Phase of Broken Dual Gauge Symmetry?

abstract:
  We study whether broken dual gauge symmetry, as detected by a monopole order
parameter introduced by the Pisa group, is necessarily associated with the
confinement phase of a lattice gauge theory. We find a number of examples,
including SU(2) gauge-Higgs theory, mixed fundamental-adjoint SU(2) gauge
theory, and pure SU(5) gauge theory, which appear to indicate a dual gauge
symmetry transition in the absence of a transition to or from a confined phase.
While these results are not necessarily fatal to the dual superconductor
hypothesis, they may pose some problems of interpretation for the present
formulation of the Pisa monopole criterion.


title:
One-dimensional Anderson Localization: Devil's staircase of Statistical
  Anomalies

abstract:
  The statistics of wavefunctions in the one-dimensional (1d) Anderson model of
localization is considered. It is shown that at any energy that corresponds to
a rational filling factor f=p/q there is a statistical anomaly which is seen in
expansion of the generating function (GF) to the order (q-2) in the disorder
parameter. We study in detail the principle anomaly at $f=1/2$ that appears in
the leading order. The transfer-matrix equation of the Fokker-Planck type with
a two-dimensional internal space is derived for GF. It is shown that the
zero-mode variant of this equation is integrable and a solution for the
generating function is found in the thermodynamic limit.


title: Hadronic Shower Energy Scale Uncertainty in the MINOS Experiment

abstract:
  In this paper we determine the model uncertainty in the calorimetric response
of the MINOS detector to hadronic showers produced by neutrino interactions.


title:
Bilayer splitting and c-axis coupling in bilayer manganites showing
  colossal magnetoresistance

abstract:
  By performing angle-resolved photoemission spectroscopy of the bilayer
colossal magnetoresistive (CMR) manganite, $La_{2-2x}Sr_{1+2x}Mn_{2}O_{7}$, we
provide the complete mapping of the Fermi level spectral weight topology. Clear
and unambiguous bilayer splitting of the in-plane 3d$_{x^2-y^2}$ band, mapped
throughout the Brillouin zone, and the full mapping of the 3d$_{3z^2-r^2}$ band
are reported. Peculiar doping and temperature dependencies of these bands imply
that as transition from the ferromagnetic metallic phase approaches, either as
a function of doping or temperature, coherence along the c-axis between planes
within the bilayer is lost, resulting in reduced interplane coupling. These
results suggest that interplane coupling plays a large role in the CMR
transition.


title:
Anomalous centrality variation of minijet angular correlations in Au-Au
  collisions at 62 and 200 GeV from STAR

abstract:
  We have measured 2D autocorrelations for all charged hadrons in STAR with
$p_{t}$ $>$ 0.15 GeV/c and $| \eta |$ $<$ 1 from Au+Au collisions at 62 and 200
GeV. The correlation structure is dominated by a peak centered at zero relative
opening angles on $\eta$ and $\phi$ which we hypothesize is caused by
minimum-bias jets (minijets). We observe a large excess of minijet correlations
in more-central Au-Au collisions relative to binary-collision scaling (more
correlated pairs than expected from surface emission or even volume emission).
We also observe a sudden increase of the minijet peak amplitude and $\eta$
width relative to binary-collision scaling of scattered partons which occurs at
an energy-dependent centrality point. There is a possible scaling of the
transition point with transverse particle density.


title:
Bloch-Kato exponential maps for local fields with imperfect residue
  fields

abstract:
  In this paper, we generalise the construction of the Bloch-Kato exponential
map to complete discrete valuation fields of mixed characteristic (0,p) whose
residue fields have a finite p-basis. As an application we prove an explicit
reciprocity law, extending a result of Cherbonnier and Colmez in the classical
case. This result relies on the calculation of the Galois cohomology of a
p-adic representation V in terms of its (phi,G)-module.


title:
Harmonic Measure for Percolation and Ising Clusters Including Rare
  Events

abstract:
  We obtain the harmonic measure of the hulls of critical percolation clusters
and Ising-model Fortuin-Kastelyn clusters using a biased random-walk sampling
technique which allows us to measure probabilities as small as 10^{-300}. We
find the multifractal D(q) spectrum including regions of small and negative q.
Our results for external hulls agree with Duplantier's theoretical predictions
for D(q) and his exponent -23/24 for the harmonic measure probability
distribution. For the complete hull, we find the probability decays with an
exponent of -1 for both systems.


title:
Detecting speculative bubbles created in experiments via decoupling in
  agent based models

abstract:
  Proving the existence of speculative financial bubbles even a posteriori has
proven exceedingly difficult so anticipating a speculative bubble ex ante would
at first seem an impossible task. Still as illustrated by the recent turmoil in
financial markets initiated by the so called subprime crisis there is clearly
an urgent need for new tools in our understanding and handling of financial
speculative bubbles. In contrast to periods of fast growth, the nature of
market dynamics profoundly changes during speculative bubbles where self
contained strategies often leads to unconditional buying. A critical question
is therefore whether such a signature can be quantified, and if so, used in the
understanding of what are the sufficient and necessary conditions in the
creation of a speculative bubble. Here we show a new technique, based on agent
based simulations, gives a robust measure of detachment of trading choices
created by feedback, and predicts the onset of speculative bubbles in
experiments with human subjects. We use trading data obtained from experiments
with humans as input to computer simulations of artificial agents that use
adaptive strategies defined from game theory....


title: An Atomic Gravitational Wave Interferometric Sensor (AGIS)

abstract:
  We propose two distinct atom interferometer gravitational wave detectors, one
terrestrial and another satellite-based, utilizing the core technology of the
Stanford 10 m atom interferometer presently under construction. Each
configuration compares two widely separated atom interferometers run using
common lasers. The signal scales with the distance between the interferometers,
which can be large since only the light travels over this distance, not the
atoms. The terrestrial experiment with baseline ~1 km can operate with strain
sensitivity ~10^(-19) / Hz^(1/2) in the 1 Hz - 10 Hz band, inaccessible to
LIGO, and can detect gravitational waves from solar mass binaries out to
megaparsec distances. The satellite experiment with baseline ~1000 km can probe
the same frequency spectrum as LISA with comparable strain sensitivity
~10^(-20) / Hz^(1/2). The use of ballistic atoms (instead of mirrors) as
inertial test masses improves systematics coming from vibrations, acceleration
noise, and significantly reduces spacecraft control requirements. We analyze
the backgrounds in this configuration and discuss methods for controlling them
to the required levels.

categories: gr-qc astro-ph hep-ph hep-th physics.atom-ph


title: UHE tau neutrino flux regeneration while skimming the Earth

abstract:
  The detection of Earth-skimming tau neutrinos has turned into a very
promising strategy for the observation of ultra-high energy cosmic neutrinos.
The sensitivity of this channel crucially depends on the parameters of the
propagation of the tau neutrinos through the terrestrial crust, which governs
the flux of emerging tau leptons that can be detected. One of the
characteristics of this propagation is the possibility of regeneration through
multiple $\nu_\tau \leftrightarrow \tau$ conversions, which are often neglected
in the standard picture. In this paper, we solve the transport equations
governing the $\nu_\tau$ propagation and compare the flux of emerging tau
leptons obtained allowing regeneration or not. We discuss the validity of the
approximation of neglecting the $\nu_\tau$ regeneration using different
scenarios for the neutrino-nucleon cross-sections and the tau energy losses.


title:
Superparaelectric phase in the ensemble of non-interacting ferroelectric
  nanoparticles

abstract:
  For the first time we predict the conditions of superparaelectric phase
appearance in the ensemble of non-interacting spherical ferroelectric
nanoparticles. The superparaelectricity in nanoparticle was defined by analogy
with superparamagnetism, obtained earlier in small nanoparticles made of
paramagnetic material. Calculations of correlation radius, energetic barriers
of polarization reorientation and polarization response to external electric
field, were performed within Landau-Ginzburg phenomenological approach for
perovskites Pb(Zr,Ti)O3, BiFeO3 and uniaxial ferroelectrics rochelle salt and
triglycine sulfate.


title:
Thermodynamic signature of a phase transition in the pseudogap phase of
  $YBa_2Cu_3O_{x}$ high-$T_C$ superconductor

abstract:
  We present here high precision magnetisation measurements in polycrystalline
$YBa_2Cu_3O_{x}$ samples, with oxygen content ranging from $x=6.19$ to
$x=7.00$. By analysing the temperature derivative of the susceptibility, we
found in the underdoped superconducting samples a singular point at a
temperature corresponding to $T_{mag}$, the temperature below which polarised
neutrons experiments have evidenced a symmetry breaking. We believe that this
is a thermodynamic indication for the existence of a phase transition in the
pseudogap state of underdoped $YBa_2Cu_3O_{x}$.


title: Relativistic Magnetic Monopole Flux Constraints from RICE

abstract:
  We report an upper limit on the flux of relativistic monopoles based on the
non-observation of in-ice showers by the Radio Ice Cherenkov Experiment (RICE)
at the South Pole. We obtain a 95% C.L. limit of order 10^{-18}/(cm^2-s-sr) for
intermediate mass monopoles of 10^7<gamma<10^{12} at the anticipated energy
E=10^{16} GeV. This bound is over an order of magnitude stronger than all
previously published experimental limits for this range of boost parameters
gamma, and exceeds two orders of magnitude improvement over most of the range.
We review the physics of radio detection, describe a Monte Carlo simulation
including continuous and stochastic energy losses, and compare to previous
experimental limits.


title: Affine algebraic groups with periodic components

abstract:
  A connected component of an affine algebraic group is called periodic if all
its elements have finite order. We give a characterization of periodic
components in terms of automorphisms with finite number of fixed points. It is
also discussed which connected groups have finite extensions with periodic
components. The results are applied to the study of the normalizer of a maximal
torus in a simple algebraic group.


title: Signatures of superconducting gap inhomogeneities in optical properties

abstract:
  Scanning tunneling spectroscopy applied to the high-$T_{c}$ cuprates has
revealed significant spatial inhomogeneity on the nanoscale. Regions on the
order of a coherence length in size show variations of the magnitude of the
superconducting gap of order $\pm20%$ or more. An important unresolved question
is whether or not these variations are also present in the bulk, and how they
influence superconducting properties. As many theories and data analyses for
high-$T_{c}$ superconductivity assume spatial homogeneity of the gap magnitude,
this is a pressing question. We consider the far-infrared optical conductivity
and evaluate, within an effective medium approximation, what signatures of
spatial variations in gap magnitude are present in various optical quantities.
In addition to the case of d-wave superconductivity, relevant to the high-$T_c$
cuprates, we have also considered s-wave gap symmetry in order to provide
expected signatures of inhomogeneities for superconductors in general. While
signatures of gap inhomogeneities can be strongly manifested in s-wave
superconductors, we find that the far-infrared optical conductivity in d-wave
is robust against such inhomogeneity.


title:
Analytical theory of forced rotating sheared turbulence. The Parallel
  case

abstract:
  Forced turbulence combined with the effect of rotation and shear flow is
studied. In a previous paper [Leprovost and Kim, PRE in press (2008)], we
considered the case where the shear and the rotation are perpendicular. Here,
we consider the complementary case of parallel rotation and shear, elucidating
how rotation and flow shear influence the generation of shear flow (e.g. the
direction of energy cascade), turbulence level, transport of particles and
momentum. In contrast with the case where rotation and shear are perpendicular,
we found that rotation affects turbulence amplitude only for very rapid
rotation ($\Omega \gg \A$) where it reduces slightly the anisotropy due to
shear flow. Also, concerning the transport properties of turbulence, we find
that rotation affects only the transport of particle and only for rapid
rotation, leading to an almost isotropic transport (whereas, in the case of
perpendicular rotation and shear, rotation favors isotropic transport even for
slow rotation).


title:
Dynamics of WIMPs in the solar system and implications for direct and
  indirect detection

abstract:
  Semi-analytic treatments of the evolution of orbits of weakly interacting
massive particles (WIMPs) in the solar system suggest that the WIMPs bound to
the solar system may enhance the direct detection rate relative to that of the
unbound population by up to a factor of order unity, and boost the flux of
neutrinos from WIMP annihilation in the Earth by up to two orders of magnitude.
To test these important but uncertain results, we perform a suite of numerical
orbit integrations to explore the properties of the bound WIMP population as a
function of the WIMP mass and the scattering cross section with baryonic
matter. For regions of WIMP parameter space presently allowed by experiments,
we find that (i) the bound WIMP population enhances the direct detection rate
by at most ~1% relative to the rate from unbound halo WIMPs; (ii) it is
unlikely that planned km^3-scale neutrino telescopes will detect neutrinos from
WIMP annihilation in the Earth; (iii) the event rate from neutrinos produced by
WIMP annihilation in the Sun may be much smaller than implied by the usual
calculations, which assume that WIMPs scattered onto bound orbits are rapidly
thermalized in the Sun.


title: Link between laboratory and astrophysical radiative shocks

abstract:
  This work provides analytical solutions describing the post-shock structure
of radiative shocks growing in astrophysics and in laboratory. The equations
including a cooling function $\Lambda \propto \rho^{\epsilon} P^{\zeta}
x^{\theta}$ are solved for any values of the exponents $\epsilon$, $\zeta$ and
$\theta$. This modeling is appropriate to astrophysics as the observed
radiative shocks arise in optically thin media. In contrast, in laboratory,
radiative shocks performed using high-power lasers present a radiative
precursor because the plasma is more or less optically thick. We study the
post-shock region in the laboratory case and compare with astrophysical shock
structure. In addition, we attempt to use the same equations to describe the
radiative precursor, but the cooling function is slightly modified. In future
experiments we will probe the PSR using X-ray diagnostics. These new
experimental results will allow to validate our astrophysical numerical codes.


title: The vanishing-off subgroup

abstract:
  In this paper, we define the vanishing-off subgroup of a nonabelian group. We
study the structure of the quotient of this subgroup and a central series
obtained from this subgroup.


title: Edge states, mass and spin gaps, and quantum Hall effect in graphene

abstract:
  Motivated by recent experiments and a theoretical analysis of the gap
equation for the propagator of Dirac quasiparticles, we assume that the physics
underlying the recently observed removal of sublattice and spin degeneracies in
graphene in a strong magnetic field is connected with the generation of both
Dirac masses and spin gaps. The consequences of such a scenario for the
existence of the gapless edge states with zigzag and armchair boundary
conditions are discussed. In the case of graphene on a half-plane with a zigzag
edge, there are gapless edge states in the spectrum only when the spin gap
dominates over the mass gap. In the case of an armchair edge, however, the
existence of the gapless edge states depends on the specific type of mass gaps.


title: The Challenge of Sub-Keplerian Rotation for Disk Winds

abstract:
  Strong magnetization makes the disks surrounding young stellar objects rotate
at rates that are too sub-Keplerian to enable the thermal launching of disk
winds from their surfaces unless the rate of gas diffusion across field lines
is dynamically fast. This under-appreciated implication of disk magnetization
poses a considerable challenge for disk-wind theory.


title:
Radio and Infrared Selected Optically Invisible Sources in the Bo\"otes
  NDWFS

abstract:
  We have combined data from the NOAO Deep Wide-Field Survey in Bootes and the
Spitzer Space Telescope to determine basic properties for sixteen optically
"invisible" MIPS 24um (OIMS) and thirty-five optically "invisible" radio (OIRS)
soruces, including their spectral energy distributions (SED) and luminosities.
Most OIMSs possess steep power-law SEDs over lambda(rest) = 1-10 um, indicating
the presence of obscured AGN in agreement with Spitzer spectroscopy. These
objects are extremely luminous at rest-frame near and mid-IR (nu L_nu(5um) ~
10^{38}-10^{39} W), consistent with accretion near the Eddington limit and
further implying that they host buried QSOs. The majority of the IRAC detected
OIRSs have flat 3.6 to 24um SEDs, implying comparable emission from stellar
photospheres and hot AGN illuminated dust. This may reflect relatively small
amounts of dust close to the central engine or current low mass accretion
rates. A small subset of OIRSs appear to be starburst dominated with
photometric redshifts from 1.0 to 4.5. The OIMSs and OIRSs with significant
starburst components have similar L_K and stellar masses (M* ~ 10^{11} M_solar)
assuming minimal AGN contribution. Roughly half of the OIRSs are not detected
by Spitzer's IRAC or MIPS. These are most likely z > 2 radio galaxies. The IRAC
detected OIRSs are more likely than OIMSs to appear non point-like in the 3.6um
and 4.5um images, suggesting that interactions play a role in triggering their
activity. The AGN powered OIMSs may represent sub-millimeter galaxies making
the transition from starburst to accretion dominance in their evolution to
current epoch massive ellipticals.


title: Beyond Nash Equilibrium: Solution Concepts for the 21st Century

abstract:
  Nash equilibrium is the most commonly-used notion of equilibrium in game
theory. However, it suffers from numerous problems. Some are well known in the
game theory community; for example, the Nash equilibrium of repeated prisoner's
dilemma is neither normatively nor descriptively reasonable. However, new
problems arise when considering Nash equilibrium from a computer science
perspective: for example, Nash equilibrium is not robust (it does not tolerate
``faulty'' or ``unexpected'' behavior), it does not deal with coalitions, it
does not take computation cost into account, and it does not deal with cases
where players are not aware of all aspects of the game. Solution concepts that
try to address these shortcomings of Nash equilibrium are discussed.


title: Defaults and Normality in Causal Structures

abstract:
  A serious defect with the Halpern-Pearl (HP) definition of causality is
repaired by combining a theory of causality with a theory of defaults. In
addition, it is shown that (despite a claim to the contrary) a cause according
to the HP condition need not be a single conjunct. A definition of causality
motivated by Wright's NESS test is shown to always hold for a single conjunct.
Moreover, conditions that hold for all the examples considered by HP are given
that guarantee that causality according to (this version) of the NESS test is
equivalent to the HP definition.


title: Towards the description of anisotropic plasma at strong coupling

abstract:
  We initiate a study of anisotropic plasma at strong coupling using the
AdS/CFT correspondence. We construct an exact dual geometry which represents a
static uniform but anisotropic system and find, that although it is singular,
it allows for a notion of `incoming' boundary conditions. We study small
fluctuations around this background and find that the dispersion relation
depends crucially on the direction of the wave-vector relative to the shape of
the anisotropy reminiscent of similar behaviour at weak coupling. We do not
find explicit instabilities to the considered order but only a huge difference
in the damping behaviour.


title:
Comment on "Ferroelectrically Induced Weak Ferromagnetism by Design", C.
  Fennie, PRL 100, 167203 (2008)

abstract:
  The question of how ferroelectric polarization is coupled to magnetism in
magnetoelectric multiferroics, in which both types of order are simultaneously
present, is of considerable scientific and practical interest. A recent Letter
\cite{fennie} presents an analysis of the important ``ABO$_3$'' class of
perovskite multiferroics. This Letter argues that antiferromagnetic
multiferroics with magnetic ions on the B site, such as the well-studied
room-temperature multiferroic bismuth ferrite (A=Bi, B=Fe), cannot show linear
magnetoelectric coupling of the form ${\bf P} \cdot ({\bf L} \times {\bf M})$.
Here ${\bf P}$ is polarization and ${\bf L}$ and ${\bf M}$ are
antiferromagnetic and ferromagnetic moments. The conclusion of Ref.
\onlinecite{fennie} is that only materials with magnetic A-site have this
coupling. This Comment presents a compact analysis of magnetoelectric coupling
in the ABO$_3$ multiferroics. We show that the argument of Ref.
\onlinecite{fennie} does forbid $E_{PLM}$ if the final low-symmetry phase
contains only one distortion that, like ${\bf P}$, breaks all inversion
symmetries. In reality, there are multiple distortions in this symmetry class,
and cross-terms generate $E_{PLM}$. Our analysis gives simple conclusions about
existence and optimization of magnetoelectric coupling in ABO$_3$ materials.


title:
Two-Gluon Production and Longitudinal Correlations in the Color Glass
  Condensate

abstract:
  We derive an analytical expression for the two-gluon production in the pA
(light-heavy) collisions, and focus specifically on the rapidity dependent
part. We approximate the gauge field from the heavy target as the Color Glass
Condensate which interacts with the light projectile whose source density
allows for a perturbative expansion. We discuss the longitudinal correlations
of produced particles. Our calculation goes in part beyond the eikonal limit
for the emitted gluons so that we can retain the exponential terms with respect
to the rapidity difference. Our expression can thus describe the short-range
correlations as well as the long-range ones for which our formula is reduced to
the known expression. In a special case of two high-pt gluons in the
back-to-back kinematics we find that dependence on the rapidity separation is
only moderate even in the diagrammatically connected part.


title:
Nonvanishing Local Scalar Invariants even in VSI Spacetimes with all
  Polynomial Curvature Scalar Invariants Vanishing

abstract:
  VSI (`vanishing scalar invariant') spacetimes have zero values for all total
scalar contractions of all polynomials in the Riemann tensor and its covariant
derivatives. However, there are other ways of concocting local scalar
invariants (nonpolynomial) from the Riemann tensor that need not vanish even in
VSI spacetimes, such as Cartan invariants. Simple examples are given that
reduce to the squared amplitude for a linearized monochromatic plane
gravitational wave. These nonpolynomial local scalar invariants are also
evaluated for non-VSI spacetimes such as Schwarzschild and Kerr and are
estimated near the surface of the earth. Similar invariants are defined for
null fluids and for electromagnetic fields.


title:
Hidden entanglement at the Planck scale: loss of unitarity and the
  information paradox

abstract:
  We discuss how relaxing the requirement of locality for quantum fields can
equip the Hilbert space of the theory with a richer structure in its
multi-particle sector. A physical consequence is the emergence of a "planckian"
mode-entanglement, invisible to an observer that cannot probe the Planck scale.
To the same observer, certain unitary processes would appear non-unitary. We
show how entanglement transfer to the additional degrees of freedom can provide
a potential way out of the black hole information paradox.


title: Neutrino Dark Energy With More Than One Neutrino Species

abstract:
  The mass varying neutrino scenario is a model that successfully explains the
origin of dark energy while at the same time solves the coincidence problem.
The model is, however, heavily constrained by its stability towards the
formation of neutrino bound states when the neutrinos become nonrelativistic.
We discuss these constraints and find that natural, adiabatic, stable models
with the right amount of dark energy today do not exist. Secondly, we explain
why using the lightest neutrino, which is still relativistic, as an explanation
for dark energy does not work because of a feedback mechanism from the heavier
neutrinos.


title:
Fermi surface and strong coupling superconductivity in single crystal
  NdFeAsO_{1-x}F_x

abstract:
  We use angle-resolved photoemission spectroscopy (ARPES) to investigate the
electronic properties of the newly discovered oxypnictide superconductor,
NdFeAsO_{1-x}F_x. We find a well-defined Fermi surface that consists of a large
hole pocket at the Brillouin zone center and a smaller electron pocket in each
corner of the Brillouin zone. The overall location and shape of the Fermi
surface agrees reasonably well with calculations. The band dispersion is quite
complicated with many flat bands located just below the chemical potential. We
observe a superconducting gap of 20 meV, which indicates that this system is in
the strong coupling regime. The emergence of a coherent peak below the critical
temperature Tc and diminished spectral weight at the chemical potential above
Tc closely resembles the spectral characteristics of the cuprates.


title: The Magnetothermal Instability in the Intracluster Medium

abstract:
  The electron mean free path in the intracluster medium (ICM) of galaxy
clusters is much larger than the gyroradius; thus, heat is transported
anisotropically along magnetic field lines. We show that the intracluster
medium is unstable to the magnetothermal instability (MTI) using MHD
simulations with anisotropic thermal conduction. As a result of the MTI, we
find that the temperature profile of the ICM can be substantially modified on
timescales of several billion years while the magnetic field is amplified by
dynamo action up to more than fifty times the original energy. We also show
that the instability drives field lines to become preferentially radial leading
to conduction that is a highly efficient fraction of the Spitzer conductivity.
As such, we present the first self-consistent calculation of the effective
thermal conductivity in the ICM.