title:
A New Moment Method for Continuum Radiative Transfer in Cosmological
  Reionization

abstract:
  We introduce a new code for computing time-dependent continuum radiative
transfer and non-equilibrium ionization states in static density fields with
periodic boundaries. Our code solves the moments of the radiative transfer
equation, closed by an Eddingtion tensor computed using a long characteristics
method. We show that pure (i.e., not source-centered) short characteristics and
the optically-thin approximation are inappropriate for computing Eddington
factors for the problem of cosmological reionization. We evolve the
non-equilibrium ionization field via an efficient and accurate (errors <1%)
technique that switches between fully implicit or explicit finite-differencing
depending on whether the local timescales are long or short compared to the
timestep. We tailor our code for the problem of cosmological reionization. In
tests, the code conserves photons, accurately treats cosmological effects, and
reproduces analytic Stromgren sphere solutions. Its chief weakness is that the
computation time for the long characteristics calculation scales relatively
poorly compared to other techniques (t_{LC} \propto N_{cells}^1.5); however, we
mitigate this by only recomputing the Eddington tensor when the radiation field
changes substantially. Our technique makes almost no physical approximations,
so it provides a way to benchmark faster but more approximate techniques. It
can readily be extended to evolve multiple frequencies, though we do not do so
here. Finally, we note that our method is generally applicable to any problem
involving the transfer of continuum radiation through a periodic volume.


title:
High accretion rates in magnetised Keplerian discs mediated by a Parker
  instability driven dynamo

abstract:
  Hydromagnetic stresses in accretion discs have been the subject of intense
theoretical research over the past one and a half decades. Most of the disc
simulations have assumed a small initial magnetic field and studied the
turbulence that arises from the magnetorotational instability. However, gaseous
discs in galactic nuclei and in some binary systems are likely to have
significant initial magnetisation. Motivated by this, we performed ideal
magnetohydrodynamic simulations of strongly magnetised, vertically stratified
discs in a Keplerian potential. Our initial equilibrium configuration, which
has an azimuthal magnetic field in equipartion with thermal pressure, is
unstable to the Parker instability. This leads to the expelling of magnetic
field arcs, anchored in the midplane of the disc, to around five scale heights
from the midplane. Transition to turbulence happens primarily through
magnetorotational instability in the resulting vertical fields, although
magnetorotational shear instability in the unperturbed azimuthal field plays a
significant role as well, especially in the midplane where buoyancy is weak.
High magnetic and hydrodynamical stresses arise, yielding an effective
$\alpha$-value of around 0.1 in our highest resolution run. Azimuthal magnetic
field expelled by magnetic buoyancy from the disc is continuously replenished
by the stretching of a radial field created as gas parcels slide in the linear
gravity field along inclined magnetic field lines. This dynamo process, where
the bending of field lines by the Parker instability leads to re-creation of
the azimuthal field, implies that highly magnetised discs are astrophysically
viable and that they have high accretion rates.


title: Modeling He-rich subdwarfs through the hot-flasher Scenario

abstract:
  We present 1D numerical simulations aimed at studying the hot-flasher
scenario for the formation of He-rich subdwarf stars. Sequences were calculated
for a wide range of metallicities and physical assumptions, such as the stellar
mass at the moment of the helium core flash. This allows us to study the two
previously proposed flavors of the hot-flasher scenario ("deep" and "shallow"
mixing cases) and to identify a third transition type. Our sequences are
calculated by solving simultaneously the mixing and burning equations within a
diffusive convection picture, and in the context of standard mixing length
theory. We are able to follow chemical evolution during deep-mixing events in
which hydrogen is burned violently, and therefore able to present a homogeneous
set of abundances for different metallicities and varieties of hot-flashers. We
extend the scope of our work by analyzing the effects of non-standard
assumptions, such as the effect of chemical gradients, extra-mixing at
convective boundaries, possible reduction in convective velocities, or the
interplay between difussion and mass loss. Particular emphasis is placed on the
predicted surface properties of the models.
  We find that the hot-flasher scenario is a viable explanation for the
formation and surface properties of He-sdO stars. Our results also show that,
during the early He-core burning stage, element diffusion may produce the
transformation of (post hot-flasher) He-rich atmospheres into He-deficient
ones. If this is so, then we find that He-sdO stars should be the progenitors
of some of the hottest sdB stars.


title: Supersonic quantum communication

abstract:
  When locally exciting a quantum lattice model, the excitation will propagate
through the lattice. The effect is responsible for a wealth of non-equilibrium
phenomena, and has been exploited to transmit quantum information through spin
chains. It is a commonly expressed belief that for local Hamiltonians, any such
propagation happens at a finite "speed of sound". Indeed, the Lieb-Robinson
theorem states that in spin models, all effects caused by a perturbation are
limited to a causal cone defined by a constant speed, up to exponentially small
corrections. In this work we show that for translationally invariant bosonic
models with nearest-neighbor interactions, this belief is incorrect: We prove
that one can encounter excitations which accelerate under the natural dynamics
of the lattice and allow for reliable transmission of information faster than
any finite speed of sound. The effect is only limited by the model's range of
validity (eventually by relativity). It also implies that in non-equilibrium
dynamics of strongly correlated bosonic models far-away regions may become
quickly entangled, suggesting that their simulation may be much harder than
that of spin chains even in the low energy sector.


title:
CARMA Millimeter-Wave Aperture Synthesis Imaging of the HD 32297 Debris
  Disk

abstract:
  We present the first detection and mapping of the HD 32297 debris disk at 1.3
mm with the Combined Array for Research in Millimeter-wave Astronomy (CARMA).
With a sub-arcsecond beam, this detection represents the highest angular
resolution (sub)mm debris disk observation made to date. Our model fits to the
spectral energy distribution from the CARMA flux and new Spitzer MIPS
photometry support the earlier suggestion that at least two, possibly three,
distinct grain populations are traced by the current data. The observed
millimeter map shows an asymmetry between the northeast and southwest disk
lobes, suggesting large grains may be trapped in resonance with an unseen
exoplanet. Alternatively, the observed morphology could result from the recent
breakup of a massive planetesimal. A similar-scale asymmetry is also observed
in scattered light but not in the mid-infrared. This contrast between asymmetry
at short and long wavelengths and symmetry at intermediate wavelengths is in
qualitative agreement with predictions of resonant debris disk models. With
resolved observations in several bands spanning over three decades in
wavelength, HD 32297 provides a unique testbed for theories of grain and
planetary dynamics, and could potentially provide strong multi-wavelength
evidence for an exoplanetary system.


title: Testing non-standard CP violation in neutrino propagation

abstract:
  Non-standard physics which can be described by effective four fermion
interactions may be an additional source of CP violation in the neutrino
propagation. We discuss the detectability of such a CP violation at a neutrino
factory. We assume the current baseline setup of the international design study
of a neutrino factory (IDS-NF) for the simulation. We find that the CP
violation from certain non-standard interactions is, in principle, detectable
significantly below their current bounds -- even if there is no CP violation in
the standard oscillation framework. Therefore, a new physics effect might be
mis-interpreted as the canonical Dirac CP violation, and a possibly even more
exciting effect might be missed.


title: Lithium Depletion of Nearby Young Stellar Associations

abstract:
  We estimate cluster ages from lithium depletion in five pre-main-sequence
groups found within 100 pc of the Sun: TW Hydrae Association, Eta Chamaeleontis
Cluster, Beta Pictoris Moving Group, Tucanae-Horologium Association and AB
Doradus Moving Group. We determine surface gravities, effective temperatures
and lithium abundances for over 900 spectra through least squares fitting to
model-atmosphere spectra. For each group, we compare the dependence of lithium
abundance on temperature with isochrones from pre-main-sequence evolutionary
tracks to obtain model dependent ages. We find that the Eta Chamaelontis
Cluster and the TW Hydrae Association are the youngest, with ages of 12+/-6 Myr
and 12+/-8 Myr, respectively, followed by the Beta Pictoris Moving Group at
21+/-9 Myr, the Tucanae-Horologium Association at 27+/-11 Myr, and the AB
Doradus Moving Group at an age of at least 45 Myr (where we can only set a
lower limit since the models -- unlike real stars -- do not show much lithium
depletion beyond this age). Here, the ordering is robust, but the precise ages
depend on our choice of both atmospheric and evolutionary models. As a result,
while our ages are consistent with estimates based on Hertzsprung-Russell
isochrone fitting and dynamical expansion, they are not yet more precise. Our
observations do show that with improved models, much stronger constraints
should be feasible: the intrinsic uncertainties, as measured from the scatter
between measurements from different spectra of the same star, are very low:
around 10 K in effective temperature, 0.05 dex in surface gravity, and 0.03 dex
in lithium abundance.


title: On the mechanism for orbital-ordering in KCuF3

abstract:
  The Mott insulating perovskite KCuF3 is considered the archetype of an
orbitally-ordered system. By using the LDA+dynamical mean-field theory (DMFT)
method, we investigate the mechanism for orbital-ordering (OO) in this
material. We show that the purely electronic Kugel-Khomskii super-exchange
mechanism (KK) alone leads to a remarkably large transition temperature of T_KK
about 350 K. However, orbital-order is experimentally believed to persist to at
least 800 K. Thus Jahn-Teller distortions are essential for stabilizing
orbital-order at such high temperatures.


title:
Time-dependent and time-integrated angular analysis of $B\to\phi
  K^0_S\pi^0$ and $\phi K^\pm\pi^\mp$

abstract:
  We perform a time-dependent and time-integrated angular analysis of the
decays $B^0\to\phi K^{*}(892)^0$, $\phi K^{*}_2(1430)^0$, and
$\phi(K\pi)^{*0}_{0}$ with the final sample of about 465 million $\BB$ pairs
recorded with the $\babar$ detector. Twenty-four parameters are investigated,
including the branching fractions, CP-violation parameters, and parameters
sensitive to final-state interactions. We use the dependence on the $K\pi$
invariant mass of the interference between the scalar and vector or tensor
components to resolve discrete ambiguities of the strong and weak phases. We
use the time-evolution of the $B\to\phi K^0_S\pi^0$ channel to extract the
CP-violation phase difference $\Delta\phi_{00}=0.28\pm0.42\pm 0.04$ between the
$B$ and $\Bbar$ decay amplitudes. When the $B\to\phi K^\pm\pi^\mp$ channel is
included, the fractions of longitudinal polarization ${f_L}$ of the
vector-vector and vector-tensor decay modes are measured to be
$0.494\pm0.034\pm0.013$ and $0.901^{+0.046}_{-0.058}\pm 0.037$, respectively.
This polarization pattern requires the presence of a positive-helicity
amplitude in the vector-vector decay from a currently unknown source.


title: Formal and Informal Model Selection with Incomplete Data

abstract:
  Model selection and assessment with incomplete data pose challenges in
addition to the ones encountered with complete data. There are two main reasons
for this. First, many models describe characteristics of the complete data, in
spite of the fact that only an incomplete subset is observed. Direct comparison
between model and data is then less than straightforward. Second, many commonly
used models are more sensitive to assumptions than in the complete-data
situation and some of their properties vanish when they are fitted to
incomplete, unbalanced data. These and other issues are brought forward using
two key examples, one of a continuous and one of a categorical nature. We argue
that model assessment ought to consist of two parts: (i) assessment of a
model's fit to the observed data and (ii) assessment of the sensitivity of
inferences to unverifiable assumptions, that is, to how a model described the
unobserved data given the observed ones.


title: Discrete Affine Surfaces based on Quadrangular Meshes

abstract:
  In this paper we are interested in defining affine structures on discrete
quadrangular surfaces of the affine three-space. We introduce, in a
constructive way, two classes of such surfaces, called respectively indefinite
and definite surfaces. The underlying meshes for indefinite surfaces are
asymptotic nets satisfying a non-degeneracy condition, while the underlying
meshes for definite surfaces are non-degenerate conjugate nets satisfying a
certain natural condition. In both cases we associate to any of these nets
several discrete affine invariant quantities: a metric, a normal and a
co-normal vector fields, and a mean curvature. Moreover, we derive structural
and compatibility equations which are shown to be necessary and sufficient
conditions for the existence of a discrete quadrangular surface with a given
affine structure.


title:
Pattern selection in parametrically-driven arrays of nonlinear
  resonators

abstract:
  We study the problem of pattern selection in an array of
parametrically-driven nonlinear resonators with application to
microelectromechanical and nanoelectromechanical systems (MEMS & NEMS), using
an amplitude equation recently derived by Bromberg, Cross, and Lifshitz [PRE
73, 016214 (2006)]. We describe the transitions between standing-wave patterns
of different wave numbers as the drive amplitude is varied either
quasistatically, abruptly, or as a linear ramp in time. We find novel
hysteretic effects, which are confirmed by numerical integration of the
original equations of motion of the interacting nonlinear resonators.


title:
Painl\'eve III and a singular linear statistics in Hermitian random
  matrix ensembles I

abstract:
  In this paper, we study a certain linear statistics of the unitary Laguerre
ensembles, motivated in part by an integrable quantum field theory at finite
temperature. It transpires that this is equivalent to the characterization of a
sequence of polynomials orthogonal with respect to the weight $$
w(x)=w(x,s):=x^{\al}\rme^{-x}\rme^{-s/x}, \quad 0\leq x<\infty, \al>0, s>0, $$
namely, the determination of the associated Hankel determinant and recurrence
coefficients. Here $w(x,s)$ is the Laguerre weight $x^{\al}\:\rme^{-x}$
'perturbed' by a multiplicative factor $\rme^{-s/x},$ which induces an
infinitely strong zero at the origin.
  For polynomials orthogonal on the unit circle, a particular example where
there are explicit formulas, the weight of which has infinitely strong zeros,
was investigated by Pollazcek and Szeg\"o many years ago. Such weights are said
to be 'singular' or irregular due to the violation of the Szeg\"o condition.
  In our problem, the linear statistics is a sum of the reciprocal of positive
random variables $\{x_j:j=1,..,,n\};$ $\sum_{j=1}^{n}1/x_j.$
  We show that the moment generating function, or the Laplace transform of the
probability density function of this linear statistics is expressed as the
ratio of Hankel determinants and as an integral of the combination of a
particular third Painlev\'e function.


title: Vector space bases associated to vanishing ideals of points

abstract:
  We discuss four different constructions of vector space bases associated to
vanishing ideals of points. We show how to compute normal forms with respect to
these bases and give new complexity bounds. As an application, we improve the
computational algebra approach to the reverse engineering of gene regulatory
networks.


title: Magnetic field modification of ultracold molecule-molecule collisions

abstract:
  We present an accurate quantum mechanical study of molecule-molecule
collisions in the presence of a magnetic field. The work focusses on the
analysis of elastic scattering and spin relaxation in collisions of
O2(3Sigma_g) molecules at cold (~0.1 K) and ultracold (~10^{-6} K)
temperatures. Our calculations show that magnetic spin relaxation in
molecule-molecule collisions is extremely efficient except at magnetic fields
below 1 mT. The rate constant for spin relaxation at T=0.1 K and a magnetic
field of 0.1 T is found to be as large as 6.1 x 10^{-11} cm3/s. The magnetic
field dependence of elastic and inelastic scattering cross sections at
ultracold temperatures is dominated by a manifold of Feshbach resonances with
the density of ~100 resonances per Tesla for collisions of molecules in the
absolute ground state. This suggests that the scattering length of ultracold
molecules in the absolute ground state can be effectively tuned in a very wide
range of magnetic fields. Our calculations demonstrate that the number and
properties of the magnetic Feshbach resonances are dramatically different for
molecules in the absolute ground and excited spin states. The density of
Feshbach resonances for molecule-molecule scattering in the low-field-seeking
Zeeman state is reduced by a factor of 10.


title: Remarks on KdV-type Flows on Star-Shaped Curves

abstract:
  We study the relation between the centro-affine geometry of star-shaped
planar curves and the projective geometry of parametrized maps into $\RP^1$. We
show that projectivization induces a map between differential invariants and a
bi-Poisson map between Hamiltonian structures. We also show that a Hamiltonian
evolution equation for closed star-shaped planar curves, discovered by Pinkall,
has the Schwarzian KdV equation as its projectivization. (For both flows, the
curvature evolves by the KdV equation.) Using algebro-geometric methods and the
relation of group-based moving frames to AKNS-type representations, we
construct examples of closed solutions of Pinkall's flow associated with
periodic finite-gap KdV potentials.


title: Elastic $K\pi$ amplitude: a simple model

abstract:
  We present a chiral model for the $J=0, I=1/2,$ elastic $K\p$ amplitude,
suited to be employed in $D^+ \rar K^- \p^+ \p^+$ data analyses and valid
between threshold and $1.5 $GeV. Although not as precise as other versions
available in the literature, it is rather simple and incorporates the essential
physics in this energy domain. In the case of the $K$-matrix approximation, the
model allows the pole structure of the $K\p$ amplitude to be understood by
solving a quadratic equation in $s$. We show that the solutions to this
equation can be well approximated by polynomials of masses and coupling
constants. This analytic structure allows a clear understanding why, depending
on the values of one of the coupling constants, one may have one or two
physical poles. The model yields a pole, associated with the $\k$, at
$\sqrt{s}= (0.75 - i 0.24) $GeV.


title:
Ultrafast dynamics of surface electromagnetic waves in nanohole array on
  metallic film

abstract:
  We study the ultrafast dynamics of surface electromagnetic waves
photogenerated on aluminum film perforated with subwavelength holes array by
means of transient photomodulation with 100 fs time resolution. We observed a
pronounced blueshift of the resonant transmission band that reveals the
important role of plasma attenuation in the dynamics and that is inconsistent
with plasmon-polariton mechanism of extraordinary transmission. The transient
photomodulation spectra were successfully modeled within the Boltzmann equation
approach for the electron-phonon relaxation dynamics, involving non-equilibrium
hot electrons and quasi-equilibrium phonons.


title: Magnetothermodynamics of the Ising Antiferromagnet Dy2Ge2O7

abstract:
  We report systematic low temperature measurements of the DC magnetization, AC
susceptibility, and heat capacity of dysprosium pyrogermanate (Dy2Ge2O7) single
crystal and powder samples. Our results confirm that Dy2Ge2O7 is an anisotropic
antiferromagnet. The isothermal field dependent magnetization and the
integrated magnetic entropy both indicate that the Dy3+ ions behave as
Ising-like spins, analogous to those in the pyrochlore spin ice materials. Both
single-spin and collective spin relaxation phenomena appear to lead to spin
freezing in this material, again in analogy to observations in the spin ice
materials, suggesting that such phenomena may be generic to a broader class of
magnetic materials.


title:
Generalized Circulant Densities and a Sufficient Condition for
  Separability

abstract:
  In a series of papers with Kossakowski, the first author has examined
properties of densities for which the positive partial transpositrionm (PPT)
property can be readily checked. These densities were also investigated from a
different perspective by Baumgartner, Hiesmayr and Narnhofer. In this paper we
show how the support of such densities can be expressed in terms of lines in a
finite geometry and how that same structure lends itself to checking the
necessary PPT condition and to a novel sufficient condition for separability.


title: A simple 5D SO(10) GUT and sparticle masses

abstract:
  Simple supersymmetric SO(10) GUT in five dimensions is proposed, in which the
fifth dimension is compactified on the $S^1/(Z_2\times Z_2^\prime)$ orbifold
with two inequivalent branes at the orbifold fixed points. In this model, all
matter and Higgs multiplets reside on one brane (PS brane) where the Pati-Salam
(PS) symmetry is manifest, while only the SO(10) gauge multiplet resides on the
bulk. The supersymmetry breaking on the other brane (SO(10) brane) is
transmitted to the PS brane through the gaugino mediation with the bulk gauge
multiplet. We examine sparticle mass spectrum in this setup and show that the
neutralino LSP as the dark matter candidate can be realized when the
compactification scale of the fifth dimension is higher than the PS symmetry
breaking scale, keeping the successful gauge coupling unification after
incorporating threshold corrections of Kaluza-Klein modes of the bulk gauge
multiplets.


title: Exceptional Times for the Dynamical Discrete Web

abstract:
  The dynamical discrete web (DyDW),introduced in recent work of Howitt and
Warren, is a system of coalescing simple symmetric one-dimensional random walks
which evolve in an extra continuous dynamical time parameter \tau. The
evolution is by independent updating of the underlying Bernoulli variables
indexed by discrete space-time that define the discrete web at any fixed \tau.
In this paper, we study the existence of exceptional (random) values of \tau
where the paths of the web do not behave like usual random walks and the
Hausdorff dimension of the set of exceptional such \tau. Our results are
motivated by those about exceptional times for dynamical percolation in high
dimension by H\"{a}ggstrom, Peres and Steif, and in dimension two by Schramm
and Steif. The exceptional behavior of the walks in the DyDW is rather
different from the situation for the dynamical random walks of Benjamini,
H\"{a}ggstrom, Peres and Steif. For example, we prove that the walk from the
origin S^\tau_0 violates the law of the iterated logarithm (LIL) on a set of
\tau of Hausdorff dimension one. We also discuss how these and other results
extend to the dynamical Brownian web, the natural scaling limit of the DyDW.


title: Lightest U-parity Particle (LUP): a hidden sector dark matter candidate

abstract:
  We introduce a new dark matter candidate, the lightest U-parity particle
(LUP). We suggest it as a good dark matter candidate especially in the R-parity
violating supersymmetric model.


title: The Magnitude-Diameter Relation of Galaxies

abstract:
  We investigate the dependence of the luminosity-diameter relation of galaxies
on the environment. This study is based on a comparison between the 80 galaxies
in the Shapley-Ames Catalog that are located within a distance of 10 Mpc, and
the luminosity-diameter relation for galaxies in great clusters such as Virgo
and Coma. A relatively tight linear correlation is observed between the
absolute magnitudes and the logarithms of the linear diameters of galaxies
located within 10 Mpc. Surprisingly this observed power-law relationship
appears to be almost independent of environment and local mass density as
defined by Karachentsev & Malakov. However, at a given luminosity, early-type
galaxies are (on average) slightly more compact than are objects of a later
type. Unexpectedly the present results appear to indicate that the
luminosity-diameter relation for the galaxies within 10 Mpc is
indistinguishable from what is observed in the much denser Virgo cluster.
Galaxies appear to form an almost one-dimensional family in parameter space. It
remains a mystery why the luminosity-diameter relation for galaxies is so
insensitive to environment.


title:
The Highly Eccentric Pre-Main Sequence Spectroscopic Binary RX
  J0529.3+1210

abstract:
  The young system RX J0529.3+1210 was initially identified as a single-lined
spectroscopic binary. Using high-resolution infrared spectra, acquired with
NIRSPEC on Keck II, we measured radial velocities for the secondary. The method
of using the infrared regime to convert single-lined spectra into double-lined
spectra, and derive the mass ratio for the binary system, has been successfully
used for a number of young, low-mass binaries. For RX J0529.3+1210, a long-
period(462 days) and highly eccentric(0.88) binary system, we determine the
mass ratio to be 0.78+/-0.05 using the infrared double-lined velocity data
alone, and 0.73+/-0.23 combining visible light and infrared data in a full
orbital solution. The large uncertainty in the latter is the result of the
sparse sampling in the infrared and the high eccentricity: the stars do not
have a large velocity separation during most of their ~1.3 year orbit. A mass
ratio close to unity, consistent with the high end of the one sigma uncertainty
for this mass ratio value, is inconsistent with the lack of a visible light
detection of the secondary component. We outline several scenarios for a color
difference in the two stars, such as one heavily spotted component, higher
order multiplicity, or a unique evolutionary stage, favoring detection of only
the primary star in visible light, even in a mass ratio ~1 system. However, the
evidence points to a lower ratio. Although RX J0529.3+1210 exhibits no excess
at near-infrared wavelengths, a small 24 micron excess is detected, consistent
with circumbinary dust. The properties of this binary and its membership in
Lambda Ori versus a new nearby stellar moving group at ~90 pc are discussed. We
speculate on the origin of this unusual system and on the impact of such high
eccentricity on the potential for planet formation.


title: Heralded single-magnon quantum memory for photon polarization states

abstract:
  We demonstrate a heralded quantum memory based on mapping of a photon
polarization state onto a single collective-spin excitation (magnon) shared
between two spatially overlapped atomic ensembles. The polarization fidelity is
measured by quantum state tomography to be above 90(2)% for any input
polarization, which far exceeds the classical limit of 2/3. The process also
constitutes a quantum non-destructive probe that detects and regenerates a
photon without touching its - potentially undetermined - polarization.


title: On the dimension of the Hilbert scheme of curves

abstract:
  Consider a component of the Hilbert scheme whose general point corresponds to
a degree d genus g smooth irreducible and nondegenerate curve in a projective
variety X. We give lower bounds for the dimension of such a component when X is
P^3, P^4 or a smooth quadric threefold in P^4 respectively. Those bounds make
sense from the asymptotic viewpoint if we fix d and let g vary. Some examples
are constructed using determinantal varieties to show the sharpness of the
bounds for d and g in a certain range. The results can also be applied to study
rigid curves.


title:
Evidence of structural strain in epitaxial graphene layers on
  6H-SiC(0001)

abstract:
  The early stages of epitaxial graphene layer growth on the Si-terminated
6H-SiC(0001) are investigated by Auger electron spectroscopy (AES) and
depolarized Raman spectroscopy. The selection of the depolarized component of
the scattered light results in a significant increase in the C-C bond signal
over the second order SiC Raman signal, which allows to resolve submonolayer
growth, including individual, localized C=C dimers in a diamond-like carbon
matrix for AES C/Si ratio of $\sim$3, and a strained graphene layer with
delocalized electrons and Dirac single-band dispersion for AES C/Si ratio $>$6.
The linear strain, measured at room temperature, is found to be compressive,
which can be attributed to the large difference between the coefficients of
thermal expansion of graphene and SiC. The magnitude of the compressive strain
can be varied by adjusting the growth time at fixed annealing temperature.


title: Subsurface Meridional Circulation in the Active Belts

abstract:
  Temporal variations of the subsurface meridional flow with the solar cycle
have been reported by several authors. The measurements are typically averaged
over periods of time during which surface magnetic activity existed in the
regions were the velocities are calculated. The present work examines the
possible contamination of these measurements due to the extra velocity fields
associated with active regions plus the uncertainties in the data obtained
where strong magnetic fields are present. We perform a systematic analysis of
more than five years of GONG data and compare meridional flows obtained by
ring-diagram analysis before and after removing the areas of strong magnetic
field. The overall trend of increased amplitude of the meridional flow towards
solar minimum remains after removal of large areas associated with surface
activity. We also find residual circulation toward the active belts that
persist even after the removal of the surface magnetic activity, suggesting the
existence of a global pattern or longitudinally-located organized flows.


title: Compatibility of DAMA/LIBRA dark matter detection with other searches

abstract:
  The DAMA/NaI and DAMA/LIBRA annual modulation data, which may be interpreted
as a signal for the existence of weakly interacting dark matter (WIMPs) in our
galactic halo, are examined in light of null results from other experiments. We
use the energy spectrum of the combined DAMA modulation data given in 36 bins,
and include the effect of channeling. Several statistical tools are implemented
in our study: likelihood ratio with a global fit and with raster scans in the
WIMP mass and goodness-of-fit (g.o.f.). These approaches allow us to
differentiate between the preferred (global best fit) and allowed (g.o.f.)
parameter regions. It is hard to find WIMP masses and couplings consistent with
all existing data sets. For spin-independent (SI) interactions, the best fit
DAMA regions are ruled out to the 3$\sigma$ C.L., even with channeling taken
into account. However, for WIMP masses of ~8 GeV some parameters outside these
regions still yield a moderately reasonable fit to the DAMA data and are
compatible with all 90% C.L. upper limits from negative searches, when
channeling is included. For spin-dependent (SD) interactions with proton-only
couplings, a range of masses below 10 GeV is compatible with DAMA and other
experiments, with and without channeling, when SuperK indirect detection
constraints are included; without the SuperK constraints, masses as high as ~20
GeV are compatible. For SD neutron-only couplings we find no parameters
compatible with all the experiments. Mixed SD couplings are examined: e.g. ~8
GeV mass WIMPs with a_n = +/- a_p are found to be consistent with all
experiments. In short, there are surviving regions at low mass for both SI and
SD interactions; if indirect detection limits are relaxed, some SD proton-only
couplings at high masses also survive.


title: Gaslike model of social motility

abstract:
  We propose a model to represent the motility of social elements. The model is
completely deterministic, possesses a small number of parameters, and exhibits
a series of properties that are reminiscent of the behavior of comunities in
social-ecological competition; these are: (i) similar individuals attract each
other; (ii) individuals can form stable groups; (iii) a group of similar
individuals breaks into subgroups if it reaches a critical size; (iv)
interaction between groups can modify the distribution of the elements as a
result of fusion, fission, or pursuit; (v) individuals can change their
internal state by interaction with their neighbors. The simplicity of the model
and its richness of emergent behaviors, such as, for example, pursuit between
groups, make it a useful toy model to explore a diversity of situations by
changing the rule by which the internal state of individuals is modified by the
interactions with the environment.


title:
Revisiting an equivalence between maximum parsimony and maximum
  likelihood methods in phylogenetics

abstract:
  Tuffley and Steel (1997) proved that Maximum Likelihood and Maximum Parsimony
methods in phylogenetics are equivalent for sequences of characters under a
simple symmetric model of substitution with no common mechanism. This result
has been widely cited ever since. We show that small changes to the model
assumptions suffice to make the two methods inequivalent. In particular, we
analyze the case of bounded substitution probabilities as well as the molecular
clock assumption. We show that in these cases, even under no common mechanism,
Maximum Parsimony and Maximum Likelihood might make conflicting choices. We
also show that if there is an upper bound on the substitution probabilities
which is `sufficiently small', every Maximum Likelihood tree is also a Maximum
Parsimony tree (but not vice versa).


title: On Universal Cycles of Labeled Graphs

abstract:
  A universal cycle is a compact listing of a class of combinatorial objects.
In this paper, we prove the existence of universal cycles of classes of labeled
graphs, including simple graphs, trees, graphs with m edges, graphs with loops,
graphs with multiple edges (with up to m duplications of each edge), directed
graphs, hypergraphs, and k-uniform hypergraphs.


title:
Relics of structure formation: extra-planar gas and high-velocity clouds
  around the Andromeda Galaxy

abstract:
  Using the 100-m radio telescope at Effelsberg, we mapped a large area around
the Andromeda Galaxy in the 21-cm line emission of neutral hydrogen to search
for high-velocity clouds (HVCs) out to large projected distances in excess of
100 kpc. Our 3-sigma HI mass sensitivity for the warm neutral medium is 8x10^4
solar masses. We can confirm the existence of a population of HVCs with typical
HI masses of a few times 10^5 solar masses near the disc of M31. However, we
did not detect any HVCs beyond a projected distance of about 50 kpc from M31,
suggesting that HVCs are generally found in proximity of large spiral galaxies
at typical distances of a few 10 kpc. Comparison with CDM-based models and
simulations suggests that only a few of the detected HVCs could be associated
with primordial dark-matter satellites, whereas others are most likely the
result of tidal stripping. The lack of clouds beyond a projected distance of 50
kpc from M31 is also in conflict with the predictions of recent CDM structure
formation simulations. A possible solution to this problem could be ionisation
of the HVCs as a result of decreasing pressure of the ambient coronal gas at
larger distances from M31. A consequence of this scenario would be the presence
of hundreds of mainly ionised or pure dark-matter satellites around large
spiral galaxies like the Milky Way and M31.


title: Difficulties of Preserving the Leap Second

abstract:
  We examine the possibility to extend leap second extrapolation for a near
future based on some periodic terms in the Earth's rotation changes. The IERS
data, covering the interval from 1962.15 to 2006.95, are analyzed. The
difference $\Delta T$ is extrapolated till to 2035 and compared with the IERS
extrapolated values to the 2012. It can be seen that for the interval from 2006
to 2024 only 1 leap seconds (negative) will be operated.


title: Conference Summary: Magellanic System - Stars, Gas and Galaxies

abstract:
  We provide a brief overview of some key issues that came out of the IAU 256
symposium on the Magellanic System (http://www.astro.keele.ac.uk/iaus256)


title:
Circular Digraph Walks, k-Balanced Strings, Lattice Paths and Chebychev
  Polynomials

abstract:
  We count the number of walks of length n on a k-node circular digraph that
cover all k nodes in two ways. The first way illustrates the transfer-matrix
method. The second involves counting various classes of height-restricted
lattice paths. We observe that the results also count so-called k-balanced
strings of length n, generalizing a 1996 Putnam problem.


title: The action of Hecke operators on hypergeometric functions

abstract:
  We study the action of Hecke operators on the set of hypergeometric
functions. We show that the spectrum of these operators is the set of powers
n^a and that polylogarithms play a dominant role in the study of the
corresponding eigenfunctions. As a corollary, we obtain a characterization of
completely multiplicative hypergeometric coefficients.


title: Constructing word similarities in Meroitic as an aid to decipherment

abstract:
  Meroitic is the still undeciphered language of the ancient civilization of
Kush. Over the years, various techniques for decipherment such as finding a
bilingual text or cognates from modern or other ancient languages in the Sudan
and surrounding areas has not been successful. Using techniques borrowed from
information theory and natural language statistics, similar words are paired
and attempts are made to use currently defined words to extract at least
partial meaning from unknown words.


title:
The Modification of the Oppenheimer and Snyder Collapsing Dust Ball to a
  Static Ball in Discrete Space-time

abstract:
  Besides the singularity problem, the famous Oppenheimer and Snyder solution
is discovered to be of deficiency in two aspects: the internal Friedmann
space-time does not have the inherent symmetry and cannot connect to the
external Schwarzschild space-time. So the process of gravitational collapse
described by this solution is doubtful. The deficiency, together with the
singularity problem, result from the imperfection of the field theory in
continuous space-time, which is expressed by the infinite precision function
theory. The space-time structure of the Oppenheimer and Snyder dust ball is
founded to be discrete rather than continuous, and to describe the field theory
in discrete space-time it requires a function theory with finite precision.
Based on the i order real number and its equivalence class, which is defined in
the real number field, the infinite precision function theory is extended to
the finite precision function theory. The Einstein field equations are
expressed in the form of finite precision, and then the collapsing dust ball
solution in continuous space-time is modified to a static ball solution in
discrete space-time. It solves all the problems of Oppenheimer and Snyder
solution and shows that, with Planck length and Planck time as space-time
quantum, a mechanism to resist the gravitational collapse could be obtained by
the discretization of space-time.


title: A standard Hamiltonian formulation for the dynamical Casimir effect

abstract:
  We present a quantum description of photon creation via dynamical Casimir
effect based on the standard Hamiltonian formulation. The particle
representation is constructed in the expansion of field operators fixed with
the initial modes. The Hamiltonian is presented in terms of the creation and
annihilation operators with the time-varying couplings which originate from the
external properties such as an oscillating boundary or a plasma mirror of a
semiconductor slab. Some consideration is also made for the experimental
realization with a semiconductor plasma mirror.


title: Study of Bc --> J/psi pi, etac pi decays with perturbative QCD approach

abstract:
  The Bc --> J/psi pi, etac pi decays are studied with the perturbative QCD
approach. It is found that form factors and branching ratios are sensitive to
the parameters w, v, f_J/psi and f_etac, where w and v are the parameters of
the charmonium wave functions for Coulomb potential and harmonic oscillator
potential, respectively, f_J/psi and f_etac are the decay constants of the
J/psi and etac mesons, respectively. The large branching ratios and the clear
signals of the final states make the Bc --> J/psi pi, etac pi decays to be the
prospective channels for measurements at the hadron colliders


title: Observation of Cold Collisions between Trapped Ions and Trapped Atoms

abstract:
  We demonstrate a double-trap system well suited to study cold collisions
between trapped ions and trapped atoms. Using Yb$^+$ ions confined in a Paul
trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange
collisions of several isotopes for collision energies down to 400 neV (5 mK).
The measured rate coefficient of $6 \times 10^{-10}$ cm$^{3}$s$^{-1}$, constant
over four orders of magnitude in collision energy, is in good agreement with
that derived from a semiclassical Langevin model for an atomic polarizability
of 143 a.u.


title: Heterotic and M-theory Compactifications for String Phenomenology

abstract:
  In this thesis, we explore two approaches to string phenomenology. In the
first half of the work, we investigate M-theory compactifications on spaces
with co-dimension four, orbifold singularities. We construct M-theory on
C^2/Z_N by coupling 11-dimensional supergravity to a seven-dimensional
Yang-Mills theory located on the orbifold fixed-plane. The resulting action is
supersymmetric to leading non-trivial order in the 11-dim Newton constant. We
thereby reduce M-theory on a G2 orbifold with C^2/Z_N singularities, explicitly
incorporating the additional gauge fields at the singularities. We derive the
Kahler potential, gauge-kinetic function and superpotential for the resulting
N=1 four-dimensional theory. Blowing-up of the orbifold is described by a Higgs
effect and the results are consistent with the corresponding ones obtained for
smooth G2 spaces. Further, we consider flux and Wilson lines on singular loci
of the G2 space, and discuss the relation to N=4 SYM theory.
  In the second half, we develop an algorithmic framework for E8 x E8 heterotic
compactifications with monad bundles. We begin by considering cyclic Calabi-Yau
manifolds where we classify positive monad bundles, prove stability, and
compute the complete particle spectrum for all bundles. Next, we generalize the
construction to bundles on complete intersection Calabi-Yau manifolds. We show
that the class of positive monad bundles, subject to the heterotic anomaly
condition, is finite (~7000 models). We compute the particle spectrum for these
models and develop new techniques for computing the cohomology of line bundles.
There are no anti-generations of particles and the spectrum is manifestly
moduli-dependent. We further study the slope-stability of positive monad
bundles and develop a new method for proving stability of SU(n) vector bundles.


title: Vital rates from the action of mutation accumulation

abstract:
  New models for evolutionary processes of mutation accumulation allow
hypotheses about the age-specificity of mutational effects to be translated
into predictions of heterogeneous population hazard functions. We apply these
models to questions in the biodemography of longevity, including proposed
explanations of Gompertz hazards and mortality plateaus, and use them to
explore the possibility of melding evolutionary and functional models of aging.


title:
Calculation of material properties for arbitrary shape transformation
  media

abstract:
  We propose a general method to evaluate the material parameters for arbitrary
shape transformation media. By solving the original coordinates in the
transformed region via Laplace's equations, we can obtain the deformation field
numerically, in turn the material properties of the devices to be designed such
as cloaks, rotators or concentrators with arbitrary shape. Devices which have
non-fixed outer boundaries, such as beam guider, can also be designed by the
proposed method. Examples with full wave simulation are given for illustration.
In the end, wave velocity and energy change in the transformation media are
discussed with help of the deformation view.


title: A Dual Non-abelian Yang-Mills Amplitude in Four Dimensions

abstract:
  We derive an explicit formula for the vertex amplitude of dual SU(2)
Yang-Mills theory in four dimensions on the lattice, and provide an efficient
algorithm (of order j to the fourth power) for its computation. This opens the
way for both numerical and analytic development of dual methods, previously
limited to the case of three dimensions.


title:
Torque and conventional spin-Hall currents in two-dimensional spin-orbit
  coupled systems: Universal relation and hyper-selection rule

abstract:
  We investigate torque and also conventionally defined spin-Hall currents in
two-dimensional (2D) spin-orbit coupled systems of spin-1/2 particles within
the linear response Kubo formalism. We obtain some interesting relations
between the conventional and torque spin-Hall conductivities for the generic
effective Hamiltonian $H_0=\epsilon_k^0+A(k)\sigma_x-B(k)\sigma_y$, where
$A(k)=\eta^A_ik_i+\eta^A_{ij}k_ik_j+\eta^A_{ijl}k_ik_jk_l+...$,
$B(k)=\eta^B_ik_i+\eta^B_{ij}k_ik_j+\eta^B_{ijl}k_ik_jk_l+...$, and $\eta$'s
are the specific system-dependent coefficients. Specifically, we find that in
the intrinsic case the magnitude of torque spin-Hall conductivity
$\sigma^{\tau_z}_{xy}(0)$ is always twice larger than the conventional
spin-Hall conductivity $\sigma^{s_z}_{xy}(0)$, and the two conductivities have
the opposite signs, i.e., $\sigma^{\tau_z}_{xy}(0)=-2\sigma^{s_z}_{xy}(0)$.
This universal relation also holds in the presence of an uniform in-plane
magnetic field. We also find that if the energy dispersion is rotationally
invariant, there exists a hyper-angular momentum $I_z = (k\times
\partial\theta/\partial k)_z s_z + L_z$ which is conserved. Furthermore, the
hyper-angular momentum current $<{1/2}\{I_z,v_x\}>$ vanishes, and this leads to
a hyper selection rule for the conventional spin-Hall current.


title: Hard Break-Up of Two-Nucleons and QCD Dynamics of NN Interaction

abstract:
  We discus recent developments in theory of high energy two-body break-up of
few-nucleon systems. The characteristics of these reactions are such that the
hard two-body quasielastic subprocess can be clearly separated from the
accompanying soft subprocesses. We discuss in details the hard rescattering
model(HRM) in which hard photodisintegration develops in two stages. At first,
photon knocks-out an energetic quark which rescatters subsequently with a quark
of the other nucleon. The latter provides a mechanism of sharing the initial
high momentum of the photon between two outgoing nucleons. This final state
hard rescattering can be expressed through the hard NN scattering amplitude.
Within HRM we discuss hard break-up reactions involving D and 3He targets and
demonstrate how these reactions are sensitive to the dynamics of hard pn and pp
interaction. Another development of HRM is the prediction of new helicity
selection mechanism for hard two-body reactions, which was apparently confirmed
in the recent JLab experiment.


title: Butterflies I: morphisms of 2-group stacks

abstract:
  Weak morphisms of non-abelian complexes of length 2, or crossed modules, are
morphisms of the associated 2-group stacks, or gr-stacks. We present a full
description of the weak morphisms in terms of diagrams we call butterflies. We
give a complete description of the resulting bicategory of crossed modules,
which we show is fibered and biequivalent to the 2-stack of 2-group stacks. As
a consequence we obtain a complete characterization of the non-abelian derived
category of complexes of length 2. Deligne's analogous theorem in the case of
Picard stacks and abelian sheaves becomes an immediate corollary. Commutativity
laws on 2-group stacks are also analyzed in terms of butterflies, yielding new
characterizations of braided, symmetric, and Picard 2-group stacks.
Furthermore, the description of a weak morphism in terms of the corresponding
butterfly diagram allows us to obtain a long exact sequence in non-abelian
cohomology, removing a preexisting fibration condition on the coefficients
short exact sequence.


title: Numerical Models of Travel-Time Inhomogeneities in Sunspots

abstract:
  We investigate the direct contribution of strong, sunspot-like magnetic
fields to helioseismic wave travel-time shifts via two numerical forward
models, a 3D ideal MHD solver and MHD ray theory. The simulated data cubes are
analyzed using the traditional time-distance center-to-annulus measurement
technique. We also isolate and analyze the direct contribution from purely
thermal perturbations to the observed travel-time shifts, confirming some
existing ideas and bring forth new ones: (i) that the observed travel-time
shifts in the vicinity of sunspots are largely governed by MHD physics, (ii)
the travel-time shifts are sensitively dependent on frequency and phase-speed
filter parameters and the background power below the $p_1$ ridge, and finally,
(iii) despite its seeming limitations, ray theory succeeds in capturing the
essence of the travel-time variations as derived from the MHD simulations.


title: Hyperon Polarization in Unpolarized Scattering Processes

abstract:
  Transverse polarization in the Hyperon production in the unpolarized deep
inelastic scattering and pp collisions is studied in the twist-three approach,
considering the contribution from the quark-gluon-antiquark correlation
distribution in nucleon. We further compare our results for deep inelastic
scattering to a transverse momentum dependent factorization approach, and find
consistency between the two approaches in the intermediate transverse momentum
region. We also find that in pp collisions, there are only derivative terms
contributions, and the non-derivative terms vanish.


title:
Periodic Oscillations in the Intra-day Optical Light Curves of the
  Blazar S5 0716+714

abstract:
  We present results of a periodicity search of 20 intra-day variable optical
light curves of the blazar S5 0716+714, selected from a database of 102 light
curves spanning over three years. We use a wavelet analysis technique along
with a randomization test and find strong candidates for nearly periodic
variations in eight light curves, with probabilities ranging from 95% to >99%.
This is the first good evidence for periodic, or more-precisely,
quasi-periodic, components in the optical intra-day variable light curves of
any blazar. Such periodic flux changes support the idea that some active
galactic nuclei variability, even in blazars, is based on accretion disk
fluctuations or oscillations. These intra-day variability time scales are used
to estimate that the central black hole of the blazar S5 0716+714 has a mass >
2.5 \times 10^6$ M$_{\odot}$. As we did not find any correlations between the
flux levels and intra-day variability time scales, it appears that more than
one emission mechanism is at work in this blazar.


title: Large deviations for infinite dimensional stochastic dynamical systems

abstract:
  The large deviations analysis of solutions to stochastic differential
equations and related processes is often based on approximation. The
construction and justification of the approximations can be onerous, especially
in the case where the process state is infinite dimensional. In this paper we
show how such approximations can be avoided for a variety of infinite
dimensional models driven by some form of Brownian noise. The approach is based
on a variational representation for functionals of Brownian motion. Proofs of
large deviations properties are reduced to demonstrating basic qualitative
properties (existence, uniqueness and tightness) of certain perturbations of
the original process.


title: On bound states of multiple t-quarks due to Higgs exchange

abstract:
  Froggatt, Nielsen et al suggested that the Higgs boson exchange between top
quarks produces enough attraction to generate their multiple bound states.
Furthermore they claimed that the system of 6 top and 6 anti-top quarks is
bound so strongly that the binding energy nearly compensates the masses of
t-quarks, making it very light. We calculated the energy of such states more
accurately, variationally and by self-consistent mean field approximation, and
found that these state are weakly bound for massless Higgs boson and unbound
with the account for its mass.


title:
Majorana bound state in rotating superfluid 3He-A between parallel
  plates

abstract:
  A concrete and experimentally feasible example for testing the putative
Majorana zero energy state bound in a vortex is theoretically proposed for a
parallel plate geometry of superfluid $^3$He-A phase. We examine the
experimental setup in connection with ongoing rotating cryostat experiments.
The theoretical analysis is based on the well-established Ginzburg--Landau
functional, supplemented by microscopic calculations of the Bogoliubov--de
Gennes equation, both of which allow the precise location of the parameter
regions of the Majorana state to be found in realistic situations.


title:
Floer homology for negative line bundles and Reeb chords in
  pre-quantization spaces

abstract:
  In this article we prove existence of Reeb orbits for Bohr-Sommerfeld
Legendrians in certain pre-quantization spaces. We give a quantitative estimate
from below. These estimates are obtained by studying Floer homology for
fibre-wise quadratic Hamiltonian functions on negative line bundles.


title: Maximum distributions of bridges of noncolliding Brownian paths

abstract:
  The one-dimensional Brownian motion starting from the origin at time $t=0$,
conditioned to return to the origin at time $t=1$ and to stay positive during
time interval $0 < t < 1$, is called the Bessel bridge with duration 1. We
consider the $N$-particle system of such Bessel bridges conditioned never to
collide with each other in $0 < t < 1$, which is the continuum limit of the
vicious walk model in watermelon configuration with a wall. Distributions of
maximum-values of paths attained in the time interval $t \in (0,1)$ are studied
to characterize the statistics of random patterns of the repulsive paths on the
spatio-temporal plane. For the outermost path, the distribution function of
maximum value is exactly determined for general $N$. We show that the present
$N$-path system of noncolliding Bessel bridges is realized as the
positive-eigenvalue process of the $2N \times 2N$ matrix-valued Brownian bridge
in the symmetry class C. Using this fact computer simulations are performed and
numerical results on the $N$-dependence of the maximum-value distributions of
the inner paths are reported. The present work demonstrates that the
extreme-value problems of noncolliding paths are related with the random matrix
theory, representation theory of symmetry, and the number theory.

categories: cond-mat.stat-mech cond-mat.soft math-ph math.MP


title: Physics education research: Resources for graduate student instructors

abstract:
  This resource letter intends to provide physics instructors - particularly
graduate student teaching assistants - at the introductory university level
with a small but representative collection of resources to acquire a
familiarity with research in physics education for guidance in everyday
instruction. The resources are in the form of books, articles, websites,
journals, and organizations.


title:
Nucleon structure in terms of OPE with non-perturbative Wilson
  coefficients

abstract:
  Lattice calculations could boost our understanding of Deep Inelastic
Scattering by evaluating moments of the Nucleon Structure Functions. To this
end we study the product of electromagnetic currents between quark states. The
Operator Product Expansion (OPE) decomposes it into matrix elements of local
operators (depending on the quark momenta) and Wilson coefficients (as
functions of the larger photon momenta). For consistency with the matrix
elements, we evaluate a set of Wilson coefficients non-perturbatively, based on
propagators for numerous momentum sources, on a 24^3 x 48 lattice. The use of
overlap quarks suppresses unwanted operator mixing and lattice artifacts.
Results for the leading Wilson coefficients are extracted by means of Singular
Value Decomposition.


title:
Incoherence induced sign change in noise cross-correlations: A case
  study in the full counting statistics of a pure spin pump

abstract:
  The full counting statistics of a non adiabatic pure spin pump are calculated
with particular emphasis on the second and third moments. We show that
incoherence can change the sign of spin shot noise cross-correlations from
negative to positive, implying entanglement for spin-singlet electronic
sources, a truly counterintuitive result. The third moment on the other hand is
shown to be much more resilient to incoherence.


title: Quark-gluon mixed condensate of the QCD vacuum in Holographic QCD

abstract:
  We investigate the quark-gluon mixed condensate based on an AdS/QCD model.
Introducing a holographic field dual to the operator for the quark-gluon mixed
condensate, we obtain the corresponding classical equation of motion. Taking
the mixed condensate as an additional free parameter, we show that the present
scheme reproduces very well experimental data. A fixed value of the mixed
condensate is in good agreement with that of the QCD sum rules.


title: Fixed points and boundary layers in exclusion processes

abstract:
  In this paper, we show how a fixed point based boundary layer analysis can be
used to understand phases and phase transitions in asymmetric simple exclusion
processes (ASEPs) with open boundaries. In order to illustrate this method, we
choose a two-species ASEP which has interesting phase transitions not seen in
the one-species case. We also apply this method to the single species problem
where the analysis is simple but nevertheless quite insightful.


title: Gravitational excitation of high frequency QPOs

abstract:
  We discuss the possibility that high-frequency QPOs in neutron-star binary
systems may result from forced resonant oscillations of matter in the innermost
parts of the accretion disc, excited by gravitational perturbations coming from
asymmetries of the neutron star or from the companion star. We find that
neutron-star asymmetries could, in principle, be effective for inducing both
radial and vertical oscillations of relevant amplitude while the binary
companion might possibly produce significant radial oscillations but not
vertical ones. Misaligned neutron-star quadrupole moments of a size advocated
elsewhere for explaining limiting neutron star periods could be large enough
also for the present purpose.


title:
Epitaxial Zn(x)Fe(3-x)O(4) Thin Films: A Spintronic Material with
  Tunable Electrical and Magnetic Properties

abstract:
  The ferrimagnetic spinel oxide Zn(x)Fe(3-x)O(4) combines high Curie
temperature and spin polarization with tunable electrical and magnetic
properties, making it a promising functional material for spintronic devices.
We have grown epitaxial thin films with 0<=x<=0.9 on MgO(001) substrates with
excellent structural properties both in pure Ar atmosphere and an Ar/O2 mixture
by laser molecular beam epitaxy. We find that the electrical conductivity and
the saturation magnetization can be tuned over a wide range during growth. Our
extensive characterization of the films provides a clear picture of the
underlying physics of this spinel ferrimagnet with antiparallel Fe moments on
the A and B sublattice: (i) Zn substitution removes both Fe3+ moments from the
A sublattice and itinerant charge carriers from the B sublattice, (ii) growth
in finite oxygen partial pressure generates Fe vacancies on the B sublattice
also removing itinerant charge carriers, and (iii) application of both Zn
substitution and excess oxygen results in a compensation effect as Zn
substitution partially removes the Fe vacancies. A decrease (increase) of
charge carrier density results in a weakening (strengthening) of double
exchange and thereby a decrease (increase) of conductivity and the saturation
magnetization. This scenario is confirmed by the observation that the
saturation magnetization scales with the longitudinal conductivity. The
combination of tailored films with semiconductor materials such as ZnO in
multi-functional heterostructures seems to be particularly appealing.


title: Bayesian Methods for Parameter Estimation in Effective Field Theories

abstract:
  We demonstrate and explicate Bayesian methods for fitting the parameters that
encode the impact of short-distance physics on observables in effective field
theories (EFTs). We use Bayes' theorem together with the principle of maximum
entropy to account for the prior information that these parameters should be
natural, i.e.O(1) in appropriate units. Marginalization can then be employed to
integrate the resulting probability density function (pdf) over the EFT
parameters that are not of specific interest in the fit. We also explore
marginalization over the order of the EFT calculation, M, and over the
variable, R, that encodes the inherent ambiguity in the notion that these
parameters are O(1). This results in a very general formula for the pdf of the
EFT parameters of interest given a data set, D. We use this formula and the
simpler "augmented chi-squared" in a toy problem for which we generate
pseudo-data. These Bayesian methods, when used in combination with the
"naturalness prior", facilitate reliable extractions of EFT parameters in cases
where chi-squared methods are ambiguous at best. We also examine the problem of
extracting the nucleon mass in the chiral limit, M_0, and the nucleon sigma
term, from pseudo-data on the nucleon mass as a function of the pion mass. We
find that Bayesian techniques can provide reliable information on M_0, even if
some of the data points used for the extraction lie outside the region of
applicability of the EFT.

categories: hep-ph hep-lat nucl-ex nucl-th physics.data-an


title: Two-Fluid Viscous Modified Gravity on a RS Brane

abstract:
  Singularities in the dark energy late universe are discussed, under the
assumption that the Lagrangian contains the Einstein term R plus a modified
gravity term R^\alpha, where \alpha is a constant. The 4D fluid is taken to be
viscous and composed of two components, one Einstein component where the bulk
viscosity is proportional to the scalar expansion \theta, and another modified
component where the bulk viscosity is proportional to the power
\theta^{2\alpha-1}. Under these conditions it is known from earlier that the
bulk viscosity can drive the fluid from the quintessence region (w > -1) into
the phantom region (w<-1), where w is the thermodynamical parameter [I. Brevik,
Gen. Rel. Grav. 38, 1317 (2006)]. We combine this 4D theory with the 5D
Randall-Sundrum II theory in which there is a single spatially flat brane
situated at y=0. We find that the Big Rip singularity, which occurs in 4D
theory if \alpha >1/2, carries over to the 5D metric in the bulk, |y|>0. The
present investigation generalizes that of an earlier paper [I. Brevik,
arXiv:0807.1797; to appear in Eur. Phys. J. C] in which only a one-component
modified fluid was present.


title: Geometric cross sections of rotating strings and black holes

abstract:
  We study the production cross section of a highly excited string with fixed
angular momentum from an ultra-high energy collision of two light strings. We
find that the cross section exhibits geometric behavior in a certain region of
angular-momentum/impact-parameter space. This geometric behavior is common to
the differential cross sections of a black hole production with fixed angular
momentum and thus we see another correspondence between strings and black
holes.


title: Finite type invariants of words and Arnold's invariants

abstract:
  We define a new finite type invariant for stably homeomorphic class of curves
on compact oriented surfaces without boundaries and extend to a regular
homotopy invariant for spherical curves.


title:
Extension theorems for differential forms and Bogomolov-Sommese
  vanishing on log canonical varieties

abstract:
  Given a p-form defined on the smooth locus of a normal variety, and a
resolution of singularities, we study the problem of extending the pull-back of
the p-form over the exceptional set of the desingularization.
  For log canonical pairs and for certain values of p, we show that an
extension always exists, possibly with logarithmic poles along the exceptional
set. As a corollary, it is shown that sheaves of reflexive differentials enjoy
good pull-back properties. A natural generalization of the well-known
Bogomolov-Sommese vanishing theorem to log canonical threefold pairs follows.


title: Enhanced radiative strength in the quasi-continuum of 117Sn

abstract:
  Radiative strength functions of 117Sn has been measured below the neutron
separation energy using the (3He,3He'gamma) reactions. An increase in the slope
of the strength functions around E_gamma= 4.5 MeV indicates the onset of a
resonance-like structure, giving a significant enhancement of the radiative
strength function compared to standard models in the energy region 4.5 <=
E_gamma <= 8.0 MeV. For the first time, the functional form of this
resonance-like structure has been measured in an odd tin nucleus below neutron
threshold in the quasi-continuum region.


title: Reversibility of chordal SLE

abstract:
  We prove that the chordal SLE$_{\kappa}$ trace is reversible for
$\kappa\in(0,4]$.


title:
Study of intermediate two-body decays in $\bar{B}^0\to
  \Sigma_c(2455)^{0}\bar{p}\pi^{+}$

abstract:
  We present results of a detailed study of the three-body
$\bar{B}^0\to\Sigma_c(2455)^{0}\bar{p}\pi^{+}$ decay. A significant enhancement
of signal events is observed in the $\bar{p}\pi^+$ mass system near $1.5 {\rm
GeV}/c^2$ that is consistent with the presence of an intermediate baryonic
resonance $\bar{N}^0$, where $\bar{N}^0$ is the $\bar{N}(1440)^0 P_{11}$ or
$\bar{N}(1535)^0 S_{11}$ state, or an admixture of the two states. We measure
the product ${\cal B}(\bar{B}^0\to\Sigma_c(2455)^{0}\bar{N}^0)\times{\cal
B}(\bar{N}^0\to\bar{p}\pi^+)$=
($0.80\pm0.15\rm{(stat.)}\pm0.14\rm{(syst.)}\pm0.21$)$\times10^{-4}$, where the
last error is due to the uncertainty in ${\cal B}(\Lambda_c^+\to p K^-\pi^+)$.
The significance of the signal is 6.1 standard deviations. This analysis is
based on a data sample of 357 fb$^{-1}$, accumulated at the $\Upsilon(4S)$
resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$
collider.


title: Flow Faster: Efficient Decision Algorithms for Probabilistic Simulations

abstract:
  Strong and weak simulation relations have been proposed for Markov chains,
while strong simulation and strong probabilistic simulation relations have been
proposed for probabilistic automata. However, decision algorithms for strong
and weak simulation over Markov chains, and for strong simulation over
probabilistic automata are not efficient, which makes it as yet unclear whether
they can be used as effectively as their non-probabilistic counterparts. This
paper presents drastically improved algorithms to decide whether some
(discrete- or continuous-time) Markov chain strongly or weakly simulates
another, or whether a probabilistic automaton strongly simulates another. The
key innovation is the use of parametric maximum flow techniques to amortize
computations. We also present a novel algorithm for deciding strong
probabilistic simulation preorders on probabilistic automata, which has
polynomial complexity via a reduction to an LP problem. When extending the
algorithms for probabilistic automata to their continuous-time counterpart, we
retain the same complexity for both strong and strong probabilistic
simulations.


title: Some Applications of the Isoperimetric Inequality for Integral Varifolds

abstract:
  In this work the Isoperimetric Inequality for integral varifolds is used to
obtain sharp estimates for the size of the set where the density quotient is
small and to generalise Calder\'on's and Zygmund's theory of first order
differentiability for functions in Lebesgue spaces from Lebesgue measure to
integral varifolds.


title:
Associative algebra deformations of the Connes-Moscovici's Hopf algebra
  $\mathcal{H}_1$

abstract:
  We compute the second Hochschild cohomology space $HH^2(\mathcal{H}_1)$ of
Connes-Moscovici's Hopf algebra $\mathcal{H}_1$, giving the infinitesimal
deformations (up to equivalence) of the associative structure.
  $HH^2(\mathcal{H}_1)$ is shown to be one dimensional, and thus
Connes-Moscovici's formal deformation of $\mathcal{H}_1$ using Rankin-Cohen
brackets is unique up to equivalence.


title: Gauge symmetries of systems with a finite number of degrees of freedom

abstract:
  For systems with a finite number of degrees of freedom, it is shown in
[arXiv:hep-th/0303014] that first class constraints are Abelianizable if the
Faddeev-Popov determinant is not vanishing for some choice of subsidiary
constraints. Here, for irreducible first class constraint systems with SO(3) or
SO(4) gauge symmetries, including a subset of coordinates in the fundamental
representation of the gauge group, we explicitly determine the Abelianizable
and non-Abelianizable classes of constraints. For the Abelianizable class, we
explicitly solve the constraints to obtain the equivalent set of Abelian first
class constraints. We show that for non-Abelianizable constraints there exist
residual gauge symmetries which results in confinement-like phenomena.


title: Entanglement in doped Resonating Valence Bond states

abstract:
  We investigate the entanglement properties of resonating valence bond states
on a two dimensional lattice in the presence of dopants that remove electrons
from the lattice creating "holes". The movement of the holes generated by the
Hubbard Hamiltonian in the regime of strong Coloumb repulsion in this setting
could be responsible for the phenomenon of high temperature superconductivity
as hypothesised by Anderson in Science {\bf 235}, 1196, (1987). We argue that
there is a particular density of dopants (holes) where the entanglement
contained in the lattice attains its maximal value for the nearest-neighbour
RVB liquid state.


title:
Martingale approach to stochastic differential games of control and
  stopping

abstract:
  We develop a martingale approach for studying continuous-time stochastic
differential games of control and stopping, in a non-Markovian framework and
with the control affecting only the drift term of the state-process. Under
appropriate conditions, we show that the game has a value and construct a
saddle pair of optimal control and stopping strategies. Crucial in this
construction is a characterization of saddle pairs in terms of pathwise and
martingale properties of suitable quantities.


title:
Performance characteristics of positive and negative delayed feedback on
  chaotic dynamics of directly modulated InGaAsP semiconductor lasers

abstract:
  The chaotic dynamics of directly modulated semiconductor lasers with delayed
optoelectronic feedback is studied numerically. The effects of positive and
negative delayed optoelectronic feedback in producing chaotic outputs from such
lasers with nonlinear gain reduction in its optimum value range is investigated
using bifurcation diagrams. The results are confirmed by calculating the
Lyapunov exponents. A negative delayed optoelectronic feedback configuration is
found to be more effective in inducing chaotic dynamics to such systems with
nonlinear gain reduction factor in the practical value range.


title: Bi-stability in voltage-biased NISIN structures

abstract:
  As a generic example of a voltage-driven superconducting structure we study a
short superconductor connected to normal leads by means of low transparency
tunnel junctions, with a voltage bias $V$ between the leads. The
superconducting order parameter $\Delta$ is to be determined self-consistently.
We study the stationary states of the system as well as the dynamics after a
perturbation. We find a region in parameter space where there are two stable
stationary states at a given voltage. These bi-stable states are distinguished
by distinct values of the superconducting order parameter $\Delta$ and of the
current between the leads. We have evaluated (1) the multi-valued
superconducting order parameter $\Delta$ at given $V$; (2) the current between
the leads at a given V; and (3) the critical voltage at which superconductivity
in the island ceases. With regards to dynamics, we find numerical evidence that
the stationary states are stable and that no complicated non-stationary regime
can be induced by changing the voltage. This result is somewhat unexpected and
by no means trivial, given the fact that the system is driven out of
equilibrium. The response to a change in the voltage is always gradual, even in
the regime where changing the interaction strength induces rapid anharmonic
oscillations of the order parameter.


title: Bloch-like Electronic Wave Functions in Two-Dimensional Quasicrystals

abstract:
  Electrons in quasicrystals generically possess critical wave functions that
are neither exponentially-localized nor extended, but rather decay
algebraically in space. Nevertheless, motivated by recent calculations on the
square and cubic Fibonacci quasicrystals, we investigate whether it is possible
to obtain extended wave functions expressed as linear combinations of
degenerate, or nearly-degenerate, critical eigenfunctions. We find that not
only is this possible, but that the wave functions that emerge are Bloch-like,
exhibiting the quasiperiodic long-range order of the underlying quasicrystal.
We discuss the significance of this result for the study of electronic
properties of real quasicrystals.


title: A Sobolev Poincar\'e type inequality for integral varifolds

abstract:
  In this work a local inequality is provided which bounds the distance of an
integral varifold from a multivalued plane (height) by its tilt and mean
curvature. The bounds obtained for the exponents of the Lebesgue spaces
involved are shown to be sharp.


title: Degree-distribution Stability of Growing Networks

abstract:
  In this paper, we abstract a kind of stochastic processes from evolving
processes of growing networks, this process is called growing network Markov
chains. Thus the existence and the formulas of degree distribution are
transformed to the corresponding problems of growing network Markov chains.
First we investigate the growing network Markov chains, and obtain the
condition in which the steady degree distribution exists and get its exact
formulas. Then we apply it to various growing networks. With this method, we
get a rigorous, exact and unified solution of the steady degree distribution
for growing networks.


title:
Approaching the Dirac point in high mobility multi-layer epitaxial
  graphene

abstract:
  Multi-layer epitaxial graphene (MEG) is investigated using far infrared (FIR)
transmission experiments in the different limits of low magnetic fields and
high temperatures. The cyclotron-resonance like absorption is observed at low
temperature in magnetic fields below 50 mT, allowing thus to probe the nearest
vicinity of the Dirac point and to estimate the conductivity in nearly undoped
graphene. The carrier mobility is found to exceed 250,000 cm$^2$/(V.s). In the
limit of high temperatures, the well-defined Landau level (LL) quantization is
observed up to room temperature at magnetic fields below 1 T, a phenomenon
unique in solid state systems. A negligible increase in the width of the
cyclotron resonance lines with increasing temperature indicates that no
important scattering mechanism is thermally activated, supporting recent
expectations of high room-temperature mobilities in graphene.


title: Recent HERA Results on Leptoquarks and other SUSY-related Signatures

abstract:
  The HERA ep collider and the experiments H1 and ZEUS operated from 1994-2007.
A total integrated luminosity of almost 1 fb^-1 was collected at centre-of-mass
energies up to 320 GeV. Results from searches for leptoquarks and squarks,
final states with an isolated lepton and missing transverse momentum and final
states with multi-leptons are presented. The leptoquark limits are interpreted
in terms of limits on squark production in SUSY models with R-parity violating
couplings.


title: Tiny Graviton Matrix Theory On Time-Dependent Background

abstract:
  In this article we construct a tiny graviton matrix model for type IIB string
theory on a plane-wave background with null dilaton. For the linear null
dilaton case, we analyze its vacuum and the excitation spectrum around the
vacuum, and discuss the time-dependent fuzzy three-sphere solutions and their
evolution. It turns out that at very late time the non-Abelian fuzzy degrees of
freedom disappear, which indicates the appearance of perturbative strings.


title:
Second order rectifiability of integral varifolds of locally bounded
  first variation

abstract:
  In this work it is shown that every integral varifold in an open subset of
Euclidian space of locally bounded first variation can be covered by a
countable collection of submanifolds of class C^2. Moreover, the mean curvature
of each member of the collection agrees with the mean curvature of the varifold
almost everywhere with respect to the varifold.


title:
Structural and critical current properties in polycrystalline
  SmO1-xFxFeAs

abstract:
  A series of polycrystalline SmO1-xFxFeAs bulks (x=0.15, 0.2, 0.3 and 0.4)
were prepared by the conventional solid state reaction. Resistivity,
susceptibility, magnetic hysteresis, critical current density and
microstructure of these samples have been investigated. It is found that
critical transition temperature Tc increases steadily with increasing fluorine
content, with the highest onset Tc=53 K at x=0.4. On the other hand, the
superconductivity seems correlated with lattice constants; that is, Tc rises
with the shrinkage of a-axis while resistivity increases with the enlargement
of c-axis. A global critical current density of 1.1x10^4 A/cm^2 at 5 K in self
field was achieved in the purest sample. A method of characterization of
inter-grain current density is proposed. This method gives an inter-grain Jc of
3.6x10^3 A/cm^2 at 5 K in self field, in contrast to the intra-grain Jc of 10^6
A/cm^2. The effect of composition gradients on the inter-grain Jc in
SmO1-xFxFeAs is also discussed.


title: Supersymmetry and Polytopes

abstract:
  We make an imaginative comparison between the Minimal Supersymmetric Standard
Model and the 24-cell polytope in four dimensions, the Octacube.


title:
The FIRST-2MASS Red Quasar Survey II: An anomalously high fraction of
  LoBALs in searches for dust-reddened quasars

abstract:
  We present results on a survey to find extremely dust-reddened Type-1
Quasars. Combining the FIRST radio survey, the 2MASS Infrared Survey and the
Sloan Digital Sky Survey, we have selected a candidate list of 122 potential
red quasars. With more than 80% spectroscopically identified objects, well over
50% are classified as dust-reddened Type 1 quasars, whose reddenings (E(B-V))
range from approximately 0.1 to 1.5 magnitudes. They lie well off the color
selection windows usually used to detect quasars and many fall within the
stellar locus, which would have made it impossible to find these objects with
traditional color selection techniques. The reddenings found are much more
consistent with obscuration happening in the host galaxy rather than stemming
from the dust torus. We find an unusually high fraction of Broad Absorption
Line (BAL) quasars at high redshift, all but one of them belonging to the Low
Ionization BAL (LoBAL) class and many also showing absorption the metastable
FeII line (FeLoBAL). The discovery of further examples of dust-reddened LoBAL
quasars provides more support for the hypothesis that BAL quasars (at least
LoBAL quasars) represent an early stage in the lifetime of the quasar. The fact
that we see such a high fraction of BALs could indicate that the quasar is in a
young phase in which quasar feedback from the BAL winds is suppressing star
formation in the host galaxy.


title: A Roche Model for Uniformly Rotating Rings

abstract:
  A Roche model for describing uniformly rotating rings is presented and the
results are compared with numerical solutions to the full problem for
polytropic rings. In the thin ring limit, the surfaces of constant pressure
including the surface of the ring itself are given in analytic terms, even in
the mass-shedding case.


title: Conductance through analytic constrictions

abstract:
  We study the dependence of the intrinsic conductance of a nanocontact on its
shape by using the recursion-transfer-matrix method. Hour-glass, torus, and
spherical shapes are defined through analytic potentials, the latter two
serving as rough models for ring-like and spherical molecules, respectively.
The sensitivity of the conductance to geometric details is analyzed and
discussed. Strong resonance effects are found for a spherical contact weakly
coupled to electron reservoirs.


title:
Doping evolution of the electronic specific heat coefficient in
  slightly-doped La2-xSrxCuO4 single crystals

abstract:
  Detailed doping dependence of the electronic specific heat coefficient gamma
is studied for La2-xSrxCuO4 (LSCO) single crystals in the slightly-doped
regime. We find that gamma systematically increases with doping, and
furthermore, even for the samples in the antiferromagnetic (AF) regime, gamma
already acquires finite value and grows with x. This suggests that finite
electronic density of states (DOS) is created in the AF regime where the
transport shows strong localization at low temperatures, and this means the
system is not a real insulator with a clear gap even though it still keeps long
range AF order.


title: How to calculate colourful cross sections efficiently

abstract:
  Different methods for the calculation of cross sections with many QCD
particles are compared. To this end, CSW vertex rules, Berends-Giele recursion
and Feynman-diagram based techniques are implemented as well as various methods
for the treatment of colours and phase space integration. We find that
typically there is only a small window of jet multiplicities, where the CSW
technique has efficiencies comparable or better than both of the other two
methods.


title:
AGILE detection of variable gamma-ray activity from the blazar S5
  0716+714 during September-October 2007

abstract:
  We report the gamma-ray activity from the Intermediate BL Lac S5 0716+714
during 2007 September-October observations by the AGILE satellite, coincident
with a period of intense optical activity of the source monitored by GASP-WEBT.
AGILE observed the source with its two co-aligned imagers, the Gamma-Ray
Imaging Detector (GRID) and the hard X-ray imager (Super-AGILE) sensitive in
the energy range 30 MeV-50 GeV and 18-60 keV respectively, in two different
periods: the first between 4 and 23 September 2007, the second between 24
October and 1 November 2007. Over the period 7-12 September, AGILE detected
gamma-ray emission from the source at a significance level of 9.6-sigma with an
average flux (E>100 MeV) of (97+/-15) x 10^{-8} photons cm^{-2} s^{-1},
increasing by a factor of at least four within three days. No emission was
detected by Super-AGILE in the energy range 18-60 keV, with a 3-sigma upper
limit of 10 mCrab in 335 ksec. The gamma-ray flux of S5 0716+714 detected by
AGILE is the highest ever detected for this blazar and one of the most intense
gamma-ray fluxes detected from a BL Lac object. The Spectral Energy
Distribution (SED) of mid-September seems to be consistent with the synchrotron
self-Compton (SSC) emission model, but only by including two SSC components
with different variability. In October 2007 AGILE repointed toward S5 0716+714
following an intense optical flare, measuring an average flux of (47+/-11) x
10^{-8} photons cm^{-2} s^{-1} at a significance level of 6.0-sigma. The
gamma-ray flux during both AGILE pointings appears to be highly variable on
timescales of 1 day.


title: Comix, a new matrix element generator

abstract:
  We present a new tree-level matrix element generator, based on the colour
dressed Berends-Giele recursive relations. We discuss two new algorithms for
phase space integration, dedicated to be used with large multiplicities and
colour sampling.


title: How do we interrogate the electrons without roughing them up?

abstract:
  Electrons are indistinguishable, but the energy of each electron is different
in different materials and if we can exploit this energy, then we can
systematically study the changes of electronic properties in non free-electron
metals.


title: Pseudocyclic association schemes and strongly regular graphs

abstract:
  Let X be a pseudocyclic association scheme in which all the nontrivial
relations are strongly regular graphs with the same eigenvalues. We prove that
the principal part of the first eigenmatrix of X is a linear combination of an
incidence matrix of a symmetric design and the all-ones matrix. Amorphous
pseudocyclic association schemes are examples of such association schemes whose
associated symmetric design is trivial. We present several non-amorphous
examples, which are either cyclotomic association schemes, or their fusion
schemes. Special properties of symmetric designs guarantee the existence of
further fusions, and the two known non-amorphous association schemes of class 4
discovered by van Dam and by the authors, are recovered in this way. We also
give another pseudocyclic non-amorphous association scheme of class 7 on
GF(2^{21}), and a new pseudocyclic amorphous association scheme of class 5 on
GF(2^{12}).


title: Study of \Omega_c^0 and \Omega_c^{*0} Baryons at Belle

abstract:
  We report results from a study of the charmed double strange baryons
\Omega_c^0 and \Omega_c^{*0} at Belle. The \Omega_c^0 is reconstructed using
the \Omega_c^0 --> \Omega^- \pi^+ decay mode, and its mass is measured to be
(2693.6 \pm 0.3 {+1.8 \atop -1.5}) MeV/c^2. The \Omega_c^{*0} baryon is
reconstructed in the \Omega_c^0 \gamma mode. The mass difference
M_{\Omega_c^{*0}} - M_{\Omega_c^0} is measured to be (70.7 \pm 0.9 {+0.1 \atop
-0.9}) MeV/c^2. The analysis is performed using 673 fb^{-1} of data on and near
the \Upsilon(4S) collected with the Belle detector at the KEKB
asymmetric-energy e^+e^- collider.


title: Entanglement control in one-dimensional $s=1/2$ random XY spin chain

abstract:
  The entanglement in one-dimensional random XY spin systems where the
impurities of exchange couplings and the external magnetic fields are
considered as random variables is investigated by solving the different
spin-spin correlation functions and the average magnetization per spin. The
entanglement dynamics near particular locations of the system is also studied
when the exchange couplings (or the external magnetic fields) satisfy three
different distributions(the Gaussian distribution, double-Gaussian
distribution, and bimodal distribution). We find that the entanglement can be
controlled by varying the strength of external magnetic field and the different
distributions of impurities. Moreover, the entanglement of some
nearest-neighboring qubits can be increased for certain parameter values of the
three different distributions.


title:
Mean-field dynamics of a two-mode Bose-Einstein condensate subject to
  noise and dissipation

abstract:
  We discuss the dynamics of an open two-mode Bose-Hubbard system subject to
phase noise and particle dissipation. Starting from the full many-body dynamics
described by a master equation the mean-field limit is derived resulting in an
effective non-hermitian (discrete) Gross-Pitaevskii equation which has been
introduced only phenomenologically up to now. The familiar mean-field phase
space structure is substantially altered by the dissipation. Especially the
character of the fixed points shows an abrupt transition from elliptic or
hyperbolic to attractiv or repulsive, respectively. This reflects the
metastable behaviour of the corresponding many-body system which surprisingly
also leads to a significant increase of the purity of the condensate. A
comparison of the mean-field approximation to simulations of the full master
equation using the Monte Carlo wave function method shows an excellent
agreement for wide parameter ranges.


title:
Two effects relevant for the study of astrophysical reaction rates:
  gamma transitions in capture reactions and Coulomb suppression of the stellar
  enhancement

abstract:
  Nucleosynthesis processes involve reactions on several thousand nuclei, both
close to and far off stability. The preparation of reaction rates to be used in
astrophysical investigations requires experimental and theoretical input. In
this context, two interesting aspects are discussed: (i) the relevant gamma
transition energies in astrophysical capture reactions, and (ii) the newly
discovered Coulomb suppression of the stellar enhancement factor. The latter
makes a number of reactions with negative Q value more favorable for
experimental investigation than their inverse reactions, contrary to common
belief.


title: Triangulated structures induced by simplicial descent categories

abstract:
  The present paper is devoted to study the homotopy category associated with a
simplicial descent category (D,s,E) (arXiv:0808.3684v2). We prove that the
class E of equivalences has a calculus of left fractions over a quotient
category of D modulo homotopy. We study the fiber/cofiber sequences induced by
a (co)simplicial descent structure. Examples of such fiber/cofiber sequences
are deduced for (commutative) differential graded algebras, simplicial sets or
topological spaces. We prove that the homotopy category of a stable simplicial
descent category is triangulated. In addition, these triangulated structures
may be extended to the homotopy categories of diagram categories of D. As a
corollary, we obtain the triangulated structures on: (filtered) derived
categories of abelian categories, the derived category of DG-modules over a
DG-category, the stable derived category of fibrant spectra and the localized
category of mixed Hodge complexes.


title:
The entanglement in one-dimensional random XY spin chain with
  Dzyaloshinskii-Moriya interaction

abstract:
  The impurities of exchange couplings, external magnetic fields and
Dzyaloshinskii--Moriya (DM) interaction considered as Gaussian distribution,
the entanglement in one-dimensional random $XY$ spin systems is investigated by
the method of solving the different spin-spin correlation functions and the
average magnetization per spin. The entanglement dynamics at central locations
of ferromagnetic and antiferromagnetic chains have been studied by varying the
three impurities and the strength of DM interaction. (i) For ferromagnetic spin
chain, the weak DM interaction can improve the amount of entanglement to a
large value, and the impurities have the opposite effect on the entanglement
below and above critical DM interaction. (ii) For antiferromagnetic spin chain,
DM interaction can enhance the entanglement to a steady value. Our results
imply that DM interaction strength, the impurity and exchange couplings (or
magnetic field) play competing roles in enhancing quantum entanglement.


title: Constraints on the star formation histories of galaxies from z~1 to z~0

abstract:
  We present a new method to estimate the average star formation rate per unit
stellar mass (SSFR) of a stacked population of galaxies. We combine the spectra
of 600-1000 galaxies with similar stellar masses and parameterise the star
formation history of this stacked population using a set of exponentially
declining functions. The strength of the Hydrogen Balmer absorption line series
in the rest-frame wavelength range 3750-4150\AA is used to constrain the SSFR
by comparing with a library of models generated using the BC03 stellar
population code. Our method, based on a principal component analysis (PCA), can
be applied in a consistent way to spectra drawn from local galaxy surveys and
from surveys at $z \sim 1$, and is only weakly influenced by attenuation due to
dust. We apply our method to galaxy samples drawn from SDSS and DEEP2 to study
mass-dependent growth of galaxies from $z \sim 1$ to $z \sim 0$. We find that,
(1) high mass galaxies have lower SSFRs than low mass galaxies; (2) the average
SSFR has decreased from $z=1$ to $z=0$ by a factor of $\sim 3-4$, independent
of galaxy mass. Additionally, at $z \sim 1$ our average SSFRs are a factor of
$2-2.5$ lower than those derived from multi-wavelength photometry using similar
datasets. We then compute the average time (in units of the Hubble time,
$t_{\rm H}(z)$) needed by galaxies of a given mass to form their stars at their
current rate. At both $z=0$ and at $z=1$, this timescale decreases strongly
with stellar mass from values close to unity for galaxies with masses $\sim
10^{10} M_{\odot}$, to more than ten for galaxies more massive than $ 10^{11}
M_{\odot}$. Our results are in good agreement with models in which AGN feedback
is more efficient at preventing gas from cooling and forming stars in high mass
galaxies.


title: (Co)Simplicial Descent Categories

abstract:
  In this paper we study the question of how to transfer homotopic structure
from the category sD of simplicial objects in a fixed category D to D. To this
end we use a sort of homotopy colimit s : sD --> D, which we call simple
functor. For instance, the Bousfield-Kan homotopy colimit in a Quillen
simplicial model category is an example of simple functor. As a remarkable
example outside the setting of Quillen models we include Deligne simple of
mixed Hodge complexes. We prove here that the simple functor induces an
equivalence on the corresponding localized categories. We also describe a
natural structure of Brown category of cofibrant objects on sD. We use these
facts to produce cofiber sequences on the localized category of D by E, which
give rise to a natural Verdier triangulated structure in the stable case.


title: Asymptotic behaviour of thermoviscoelastic Berger plate

abstract:
  System of partial differential equations with a convolution terms and
non-local nonlinearity describing oscillations of plate due to Berger approach
and with accounting for thermal regime in terms of Coleman-Gurtin and
Gurtin-Pipkin law and fading memory of material is considered. The equation is
transformed into a dynamical system in a suitable Hilbert space which
asymptotic behaviour is analysed. Existence of the compact global attractor in
this dynamical system and some of its properties are proved in this article.
Main tool in analysis of asymptotic behaviour is stabilizability inequality.


title:
Entanglement and quantum phase transition in alternating XY spin chain
  with next-nearest neighbour interactions

abstract:
  By using the method of density-matrix renormalization-group to solve the
different spin-spin correlation functions, the nearest-neighbouring
entanglement(NNE) and next-nearest-neighbouring entanglement(NNNE) of
one-dimensional alternating Heisenberg XY spin chain is investigated in the
presence of alternating nearest neighbour interactions of exchange couplings,
external magnetic fields and next-nearest neighbouring interactions. For
dimerized ferromagnetic spin chain, NNNE appears only above the critical
dimerized interaction, meanwhile, the dimerized interaction effects quantum
phase transition point and improves NNNE to a large value. We also study the
effect of ferromagnetic or antiferromagnetic next-nearest neighboring (NNN)
interactions on the dynamics of NNE and NNNE. The ferromagnetic NNN interaction
increases and shrinks NNE below and above critical frustrated interaction
respectively, while the antiferromagnetic NNN interaction always decreases NNE.
The antiferromagnetic NNN interaction results to a larger value of NNNE in
comparison to the case when the NNN interaction is ferromagnetic.


title: The quantum critical point in CeRhIn_5: a resistivity study

abstract:
  The pressure--temperature phase diagram of CeRhIn_5 has been studied under
high magnetic field by resistivity measurements. Clear signatures of a quantum
critical point has been found at a critical pressure of p_c = 2.5 GPa. The
field induced magnetic state in the superconducting state is stable up to the
highest field. At p_c the antiferromagnetic ground-state under high magnetic
field collapses very rapidly. Clear signatures of p_c are the strong
enhancement of the resistivity in the normal state and of the inelastic
scattering term. No clear T2 temperature dependence could be found for
pressures above T_c. From the analysis of the upper critical field within a
strong coupling model we present the pressure dependence of the coupling
parameter lambda and the gyromagnetic ratio g. No signatures of a spatially
modulated order parameter could be evidenced. A detailed comparison with the
magnetic field--temperature phase diagram of CeCoIn_5 is given. The comparison
between CeRhIn_5 and CeCoIn_5 points out the importance to take into account
the field dependence of the effective mass in the calculation of the
superconducting upper critical field H_c2. It suggests also that when the
magnetic critical field H_(0) becomes lower than H_c2 (0)$, the persistence of
a superconducting pseudo-gap may stick the antiferromagnetism to H_c2 (0).