title:
Spectral analysis of 636 white dwarf - M star binaries from the Sloan
  Digital Sky Survey

abstract:
  We present a catalog of 857 white dwarf (WD)-M binaries from the sixth data
release (DR6) of the Sloan Digital Sky Survey (SDSS), most of which were
previously identified. For 636 of them, we complete a spectral analysis and
derive the basic parameters of their stellar constituents and their distances
from Earth. We attempt to measure fundamental parameters of these systems by
completing spectral analyses. We use a Chi^2 minimization technique to
decompose each combined spectrum and derive independent parameter estimates for
its components. Forty-one of the stellar duets in our spectroscopic sample are
optically resolved in their respective SDSS images. For these systems, we also
derive a minimum true spatial separation and a lower limit to their orbital
periods, typically which are some 10^4 yr. Spectra of 167 stellar duets show
significant hydrogen emission and in most cases no additional He i or He ii
features. We also find that 20 of the 636 WDs are fitted to be DOs, with 16
measured to have T_eff around 40,000 K. Furthermore, we identify 70 very
low-mass objects, which are secondaries of masses smaller than about 0.1 solar
masses, to be candidate substellar companions. Although various selection
effects may play a role, the fraction 6.4 % of WD-M star binaries with orbital
separations of around 500 AU is a criterion for evolutionary models of stellar
binary systems. Active M dwarfs are likely present in 155 Balmer-emitting
systems, corresponding to a fraction of 24.4 %. The excess of cool DOs is most
likely due to additional WDs in the DB-DO T_eff range, for which no detailed
fitting was completed. The trend of the M stars being closer to Earth than the
WD component is probably due to an underestimation of the theoretical M star
radii.


title: Spinor Bose-Einstein condensate flow past an obstacle

abstract:
  We study the flow of a spinor (F=1) Bose-Einstein condensate in the presence
of an obstacle. We consider the cases of ferromagnetic and polar spin-dependent
interactions and find that the system demonstrates two speeds of sound that are
identified analytically. Numerical simulations reveal the nucleation of
macroscopic nonlinear structures, such as dark solitons and vortex-antivortex
pairs, as well as vortex rings in one- and higher-dimensional settings
respectively, when a localized defect (e.g., a blue-detuned laser beam) is
dragged through the spinor condensate at a speed larger than the second
critical speed.


title: A Blind Search for Bursts of Very High Enery Gamma Rays with Milagro

abstract:
  Milagro is a water-Cherenkov detector that observes the extended air showers
produced by cosmic gamma rays of energies E>100GeV. The effective area of
Milagro peaks at energies E~10TeV, however it is still large even down to a few
hundred GeV (~10m^2 at 100GeV). The wide field of view (~2sr) and high duty
cycle (>90%) of Milagro make it ideal for continuously monitoring the overhead
sky for transient Very High Energy (VHE) emissions. This study searched the
Milagro data for such emissions. Even though the search was optimized primarily
for detecting the emission from Gamma-Ray Bursts (GRBs), it was still sensitive
to the emission from the last stages of the evaporation of Primordial Black
Holes or to any other kind of phenomena that produce bursts of VHE gamma rays.
Measurements of the GRB spectra by satellites up to few tens of GeV showed no
signs of a cutoff. Even though multiple instruments sensitive to $GeV/TeV$
gamma rays have performed observations of GRBs, there has not yet been a
definitive detection of such an emission yet. One of the reasons for that is
that gamma rays with energies E>~100GeV are attenuated by interactions with the
extragalactic background light or are absorbed internally at the site of the
burst. There are many models that predict VHE gamma-ray emission from GRBs. A
detection or a constraint of such an emission can provide useful information on
the mechanism and environment of GRBs. This study performed a blind search of
the Milagro data of the last five years for bursts of VHE gamma rays with
durations ranging from 100musec to 316sec. No GRB localization was provided by
an external instrument. Instead, the whole dataset was thoroughly searched in
time, space, and duration. No significant events were detected. Upper limits
were placed on the VHE emission from GRBs.


title: Shape invariance in prepotential approach to exactly solvable models

abstract:
  In supersymmetric quantum mechanics, exact-solvability of one-dimensional
quantum systems can be classified only with an additional assumption of
integrability, the so-called shape invariance condition. In this paper we show
that in the prepotential approach we proposed previously, shape invariance is
automatically satisfied and needs not be assumed.

categories: math-ph hep-th math.MP math.SP nlin.SI quant-ph


title: On the neutrality issue in the Polyakov-loop NJL model

abstract:
  We elucidate how the color neutrality is harmed in the Polyakov Nambu-Jona
Lasinio (PNJL) model at finite density within the adopted mean field
approximation. Also we point out how usual assumption about the diagonal form
of the Wilson loop may fail in the presence of the diquark condensate on
several grounds.


title:
Issues on drawing the State Transition Diagram for arbitrary Cellular
  Automata

abstract:
  This paper proposes several algorithms and their Cellular Automata Machine
(CAM) for drawing the State Transition Diagram (STD) of an arbitrary Cellular
Automata (CA) Rule (any neighborhood, uniform/ hybrid and null/ periodic
boundary) and length of the CA n. It also discusses the novelty, hardware cost
and the complexities of these algorithms.


title: Scalar Tetraquark Currents With Application to the QCD Sum Rule

abstract:
  We study the light scalar mesons in the QCD sum rule. We construct both the
diquark-antidiquark currents $(qq)(\bar q \bar q)$ and the meson-meson currents
$(\bar qq)(\bar qq)$. We find that there are five independent currents for both
cases, and derive the relations between them. For the meson-meson currents,
five independent currents are formed by products of color singlet $\bar q q$
pairs or color octet pairs. However, they can be related to each other, and the
relations are derived. We obtain the masses of the light scalar mesons which
are consistent with the experiments.


title:
On the quadratic normality and the triple curve of three dimensional
  subvarieties of ${\mathbb P}^5$

abstract:
  A well-known conjecture asserts that smooth threefolds $X\subset\{\mathbb
P}^5$ are quadratically normal with the only exception of the Palatini scroll.
As a corollary of a more general statement we obtain the following result,
which is related to the previous conjecture: If $X\subset\{\mathbb P}^5$ is not
quadratically normal, then its triple curve is reducible. Similar results are
also given for higher dimensional varieties.


title: On the habitability of the OGLE-2006-BLG-109L planetary system

abstract:
  We investigate the dynamics of putative Earth-mass planets in the habitable
zone (HZ) of the extrasolar planetary system OGLE-2006-BLG-109L, a close analog
of the Solar system. Our work is inspired by work of Malhotra and Minton
(2008). Using the linear Laplace-Lagrange theory, they identified a strong
secular resonance that may excite large eccentricity of orbits in the HZ.
However, due to uncertain or unconstrained orbital parameters, the sub-system
of Jupiters may be found in dynamically active region of the phase space
spanned by low-order mean-motion resonances. To generalize this secular model,
we construct a semi-analytical averaging method in terms of the restricted
problem. The secular orbits of large planets are approximated by numerically
averaged osculating elements. They are used to calculate the mean orbits of
terrestrial planets by means of a high-order analytic secular theory developed
in our previous works. We found regions in the parameter space of the problem
in which stable, quasi-circular orbits in the HZ are permitted. The excitation
of eccentricity in the HZ strongly depends on the apsidal angle of jovian
orbits. For some combinations of that angle, eccentricities and semi-major axes
consistent with the observations, a terrestrial planet may survive in low
eccentric orbits. We also study the effect of post-Newtonian gravity correction
on the innermost secular resonance.


title: Mass transfer dynamics in double degenerate binary systems

abstract:
  We present a numerical study of the mass transfer dynamics prior to the
gravitational wave-driven merger of a double white dwarf system. Recently,
there has been some discussion about the dynamics of these last stages,
different methods seemed to provide qualitatively different results. While
earlier SPH simulations indicated a very quick disruption of the binary on
roughly the orbital time scale, more recent grid-based calculations find
long-lived mass transfer for many orbital periods. Here we demonstrate how
sensitive the dynamics of this last stage is to the exact initial conditions.
We show that, after a careful preparation of the initial conditions, the
reportedly short-lived systems undergo mass transfer for many dozens of orbits.
The reported numbers of orbits are resolution-biased and therefore represent
only lower limits to what is realized in nature. Nevertheless, the study shows
convincingly the convergence of different methods to very similar results.


title:
Multi-wavelength Calibration Procedure for the Pierre Auger Observatory
  Fluorescence Detectors

abstract:
  We present a method to measure the relative spectral response of the Pierre
Auger Observatory Fluorescence Detector. The calibration was done at
wavelengths of 320, 337, 355, 380 and 405 nm using an end-to-end technique in
which the response of all detector components are combined in a single
measurement. A xenon flasher and notch-filters were used as the light source
for the calibration device. The overall uncertainty is 5%.


title: A Modified Stratified Model for 3C 273 Jet

abstract:
  We present a modified stratified jet model to interpret the observed spectral
energy distributions of knots in 3C 273 jet. Based on the hypothesis of the
single index of the particle energy spectrum at injection and identical
emission processes among all the knots, the observed difference of spectral
shape among different 3C273 knots can be understood as a manifestation of
deviation of the equivalent Doppler factor of stratified emission regions in
individual knot from a characteristic one. The summed spectral energy
distribution of all the ten knots in 3C 273 jet can be well fitted by two
components, low-energy (radio to optical) component dominated by the
synchrotron radiation and high-energy component (UV, X-ray and $\gamma$-ray)
dominated by the inverse Compton scattering of the cosmic microwave background.
This gives a consistent spectral index of $\alpha=0.88$ ($S_\nu \propto
\nu^{-\alpha}$) and a characteristic Doppler factor of 7.4. Assuming the
average of the summed spectrum as the characteristic spectrum of each knot in
the 3C273 jet, we further get a distribution of Doppler factor. We discuss the
possible implications of these results for the physical properties in 3C 273
jet. Future GeV observations with $\it GLAST$ could separate the $\gamma$-ray
emission of 3C 273 from the large scale jet and the small scale jet (i.e. the
core) through measuring the GeV spectrum.


title: Modeling Microscopic Chemical Sensors in Capillaries

abstract:
  Nanotechnology-based microscopic robots could provide accurate in vivo
measurement of chemicals in the bloodstream for detailed biological research
and as an aid to medical treatment. Quantitative performance estimates of such
devices require models of how chemicals in the blood diffuse to the devices.
This paper models microscopic robots and red blood cells (erythrocytes) in
capillaries using realistic distorted cell shapes. The models evaluate two
sensing scenarios: robots moving with the cells past a chemical source on the
vessel wall, and robots attached to the wall for longer-term chemical
monitoring. Using axial symmetric geometry with realistic flow speeds and
diffusion coefficients, we compare detection performance with a simpler model
that does not include the cells. The average chemical absorption is
quantitatively similar in both models, indicating the simpler model is an
adequate design guide to sensor performance in capillaries. However,
determining the variation in forces and absorption as cells move requires the
full model.


title: Generalized analytic functions on generalized domains

abstract:
  We define the algebra of Colombeau generalized functions on a subset A of the
space of d-dimensional generalized points. If the domain A is open, such
generalized functions can be identified with pointwise maps from A into the
ring of Colombeau generalized numbers. We study analyticity in these algebras,
if the domain is an open subset of the complex generalized points. In
particular, if the domain is an open ball for the sharp norm, we characterize
analyticity and give a unicity theorem involving the values at generalized
points.


title: Real Subpairs and Frobenius-Schur Indicators of Characters in 2-Blocks

abstract:
  Let B be a real 2-block of a finite group G. Then B has a real defect class.
Let g be an element of such a class. A defect couple of B is (D,E), where E is
a Sylow 2-subgroup of the extended centralizer C^*(g) of g, and D is the
intersection of E with the centralizer C(g). It is known that (D,E) is uniquely
determined up to G-conjugacy. We show that (D,E) determines which B-subpairs
are real. We also outline how (D,E) influences the vertices of components of
the G-permutation module corresponding to the conjugation action of G on its
involutions. We apply these methods to enumerate the Frobenius-Schur indicators
of the irreducible characters in a real block that has a dihedral defect group.
We also determine the vertices of the components of the involution module in
such a block.


title:
Family of boron fullerenes: general constructing schemes, electron
  counting rule and ab initio calculations

abstract:
  A set of general constructing schemes is unveiled to predict a large family
of stable boron monoelemental, hollow fullerenes with magic numbers 32+8k
(k>=0). The remarkable stabilities of these new boron fullerenes are then
studied by intense ab initio calculations. An electron counting rule as well as
an isolated hollow rule are proposed to readily show the high stability and the
electronic bonding property, which are also revealed applicable to a number of
newly predicted boron sheets and nanotubes.


title:
Phase diagram and large deviations in the free-energy of mean-field
  spin-glasses

abstract:
  We consider the probability distribution of large deviations in the
spin-glass free energy for the Sherrington-Kirkpatrick mean field model, i.e.
the exponentially small probability of finding a system with intensive free
energy smaller than the most likely one. This result is obtained by computing
$\Phi(n,T)=T \bar{Z^n}/ n$, i.e. the average value of the partition function to
the power $n$ as a function of $n$. We study in full details the phase diagram
of $\Phi(n,T)$ in the $(n,T)$ plane computing in particular the stability of
the replica-symmetric solution. At low temperatures we compute $\Phi(n,T)$ in
series of $n$ and $\tau=T_c-T$ at high orders using the standard hierarchical
ansatz and confirm earlier findings on the $O(n^5)$ scaling. We prove that the
$O(n^5)$ scaling is valid at all orders and obtain an exact expression for the
coefficient in term of the function $q(x)$. Resumming the series we obtain the
large deviations probability at all temperatures. At zero temperature the
analytical prediction displays a remarkable quantitative agreement with the
numerical data. A similar computation for the simpler spherical model is also
performed and the connection between large and small deviations is discussed.


title: Voronoi cells of discrete point sets

abstract:
  It is well known that all cells of the Voronoi diagram of a Delaunay set are
polytopes. For a finite point set, all these cells are still polyhedra. So the
question arises, if this observation holds for all discrete point sets: Are
always all Voronoi cells of an arbitrary, infinite discrete point set
polyhedral? In this paper, an answer to this question will be given. It will be
shown that all Voronoi cells of a discrete point set are polytopes if and only
if every point of the point set is an inner point. Furthermore, the term of a
locally finitely generated discrete point set will be introduced and it will be
shown that exactly these sets have the property of possessing only polyhedral
Voronoi cells.


title: Surface Instabilities and Magnetic Soft Matter

abstract:
  We report on the formation of surface instabilities in a layer of
thermoreversible ferrogel when exposed to a vertical magnetic field. Both
static and time dependent magnetic fields are employed. Under variations of
temperature, the viscoelastic properties of our soft magnetic matter can be
tuned. Stress relaxation experiments unveil a stretched exponential scaling of
the shear modulus, with an exponent of beta=1/3. The resulting magnetic
threshold for the formation of Rosensweig-cusps is measured for different
temperatures, and compared with theoretical predictions by Bohlius et. al. in
J. Phys.: Condens. Matter., 2006, 18, 2671-2684.


title:
Collective Charge Fluctuations in Single-Electron Processes on
  Nano-Networks

abstract:
  Using numerical modeling we study emergence of structure and
structure-related nonlinear conduction properties in the self-assembled
nanoparticle films. Particularly, we show how different nanoparticle networks
emerge within assembly processes with molecular bio-recognition binding. We
then simulate the charge transport under voltage bias via single-electron
tunnelings through the junctions between nanoparticles on such type of
networks. We show how the regular nanoparticle array and topologically
inhomogeneous nanonetworks affect the charge transport. We find long-range
correlations in the time series of charge fluctuation at individual
nanoparticles and of flow along the junctions within the network. These
correlations explain the occurrence of a large nonlinearity in the simulated
and experimentally measured current-voltage characteristics and non-Gaussian
fluctuations of the current at the electrode.


title: Numerical Evidence for the Haldane Conjecture

abstract:
  The Haldane conjecture, when applied to the Heisenberg O(3) model with a
\theta term in two dimensions, states that the correlation length \xi diverges
when \theta approaches \pi. To verify this conjecture we have numerically
simulated the model at imaginary \theta and then analytically continued the
results to real \theta. We have obtained that the value where the model should
become critical is \theta=3.10(5) in agreement with the expectation.


title:
An Arakelov Inequality in Characteristic p and Upper Bound of p-Rank
  Zero Locus

abstract:
  In this paper we show an Arakelov inequality for semi-stable families of
algebraic curves of genus $g\geq 1$ over characteristic $p$ with nontrivial
Kodaira-Spencer maps. We apply this inequality to obtain an upper bound of the
number of algebraic curves of $p-$rank zero in a semi-stable family over
characteristic $p$ with nontrivial Kodaira-Spencer map in terms of the genus of
a general closed fiber, the genus of the base curve and the number of singular
fibres. An extension of the above results to smooth families of Abelian
varieties over $k$ with $W_2$-lifting assumption is also included.


title: The Local Theory of the Cosmic Skeleton

abstract:
  The local theory of the critical lines of 2D and 3D Gaussian fields that
underline the cosmic structures is presented. In the context of cosmological
matter distribution the subset of critical lines of the 3D density field serves
to delineate the skeleton of the observed filamentary structure at large
scales. A stiff approximation used to quantitatively describe the filamentary
skeleton shows that the flux of the skeleton lines is related to the average
Gaussian curvature of the 1D (2D) sections of the field, much in the same way
as the density of the peaks. The distribution of the length of the critical
lines with threshold is analyzed in detail, while the extended descriptors of
the skeleton - its curvature and its singular points, are introduced and
briefly described. Theoretical predictions are compared to measurements of the
skeleton in realizations of Gaussian random fields in 2D and 3D. It is found
that the stiff approximation predicts accurately the shape of the differential
length, allows for analytical insight, and explicit closed form solutions.
Finally, it provides a simple classification of the singular points of the
critical lines: i) critical points; ii) bifurcation points; iii) slopping
plateaux.


title: Homotopy groups and twisted homology of arrangements

abstract:
  Recent work of M. Yoshinaga shows that in some instances certain higher
homotopy groups of arrangements map onto non-resonant homology. This is in
contrast to the usual Hurewicz map to untwisted homology, which is always the
zero homomorphism in degree greater than one. In this work we examine this
dichotomy, generalizing both results.


title:
The granularity of weakly occupied bosonic fields beyond the local
  density approximation

abstract:
  We examine ground state correlations for repulsive, quasi one-dimensional
bosons in a harmonic trap. In particular, we focus on the few particle limit
N=2,3,4,..., where exact numerical solutions of the many particle Schroedinger
equation are available employing the Multi-Configuration Time-dependent Hartree
method. Our numerical results for the inhomogeneous system are modeled with the
analytical solution of the homogeneous problem using the Bethe ansatz and the
local density approximation. Tuning the interaction strength from the weakly
correlated Gross-Pitaevskii- to the strongly correlated Tonks-Girardeau regime
reveals finite particle number effects in the second order correlation function
beyond the local density approximation.


title: Average Infrared Galaxy Spectra From Spitzer Flux Limited Samples

abstract:
  The mid-infrared spectroscopic analysis of a flux-limited sample of galaxies
with fv(24um) > 10 mJy is presented. Sources observed are taken from the
Spitzer First Look Survey (FLS) catalog and from the NOAO Deep Wide-Field
Survey region in Bootes (NDWFS). The spectroscopic sample includes 60 of the
100 sources in these combined catalogs having fv(24um) > 10 mJy. New spectra
from the Spitzer Infrared Spectrograph are presented for 25 FLS sources and for
11 Bootes AGN; these are combined with 24 Bootes starburst galaxies previously
published to determine the distribution of mid-infrared spectral
characteristics for the total 10 mJy sample. Sources have 0.01 < z < 2.4 and
41.8 < log vLv(15um) < 46.2 (ergs/s). Average spectra are determined as a
function of luminosity; lower luminosity sources (log vLv(15um) < 44.0) are
dominated by PAH features and higher luminosity sources (log vLv(15um) > 44.0)
are dominated by silicate absorption or emission. We find that a rest frame
equivalent width of 0.4um for the 6.2um PAH emission feature provides a well
defined division between lower luminosity, "pure" starbursts and higher
luminosity AGN or composite sources. Using the average spectra, fluxes fv(24um)
which would be observed with the Spitzer MIPS are predicted as a function of
redshift for sources with luminosities that correspond to the average spectra.
AGN identical to those in this 10 mJy sample could be seen to z = 3 with
fv(24um) > 1 mJy, but starbursts fall to fv(24um) < 1 mJy by z ~ 0.5. This
indicates that substantial luminosity evolution of starbursts is required to
explain the numerous starbursts found in other IRS results having fv(24um) > 1
mJy and z ~ 2.


title: Elastic Plate Deformation with Transverse Variation of Microrotation

abstract:
  The purpose of this paper is to present a new mathematical model for the
deformation of thin Cosserat elastic plates. Our approach, which is based on a
generalization of the classical Reissner plate theory, takes into account the
transverse variation of microrotation of the plates. The model assumes
polynomial approximations over the plate thickness of asymmetric stress, couple
stress, displacement, and microrotation, which are consistent with the elastic
equilibrium, boundary conditions and the constitutive relationships. Based on
the generalized Hellinger-Prange -Reissner variational principle and
strain-displacement relation we obtain the complete theory of Cosserat plate.
We also proved the solution uniqueness for the plate boundary value problem.


title: A Hilbert C*-module admitting no frames

abstract:
  We show that every infinite-dimensional commutative unital C*-algebra has a
Hilbert C*-module admitting no frames. In particular, this shows that
Kasparov's stabilization theorem for countably generated Hilbert C*-modules can
not be extended to arbitrary Hilbert C*-modules.


title:
Transverse momentum distributions of quarks in the nucleon from Lattice
  QCD

abstract:
  Transverse momentum dependent parton distribution functions (TMDPDFs) encode
information about the intrinsic motion of quarks inside the nucleon. They are
important non-perturbative ingredients in our understanding of, e.g., azimuthal
asymmetries and other qualitative features in semi-inclusive deep inelastic
scattering experiments. We present first calculations on the lattice, based on
MILC gauge configurations and propagators from LHPC. They yield polarized and
unpolarized transverse momentum dependent quark densities and enable us to test
the assumption of factorization in x and transverse momentum. The operators we
employ are non-local and contain a Wilson line, whose renormalization requires
the removal of a divergence linear in the cutoff 1/a.


title: Multiband bosons in optical lattices

abstract:
  We study a gas of repulsively interacting bosons in an optical lattice and
explore the physics beyond the lowest band Hubbard model. Utilizing a
generalized Gutzwiller ansatz, we find how the lowest band physics is modified
by the inclusion of the first excited bands. In contrast to the prediction of
the lowest band Bose-Hubbard model, a reentrant behavior of superfluidity is
envisaged as well as decreasing width of the Mott lobes at strong coupling.


title: New biorthogonal potential--density basis functions

abstract:
  We use the weighted integral form of spherical Bessel functions, and
introduce a new analytical set of complete and biorthogonal potential--density
basis functions. The potential and density functions of the new set have finite
central values and they fall off, respectively, similar to $r^{-(1+l)}$ and
$r^{-(4+l)}$ at large radii where $l$ is the latitudinal quantum number of
spherical harmonics. The lowest order term associated with $l=0$ is the perfect
sphere of de Zeeuw. Our basis functions are intrinsically suitable for the
modeling of three dimensional, soft-centred stellar systems and they complement
the basis sets of Clutton-Brock, Hernquist & Ostriker and Zhao. We test the
performance of our functions by expanding the density and potential profiles of
some spherical and oblate galaxy models.


title: Solution of heterotic Killing spinor equations and special geometry

abstract:
  We outline the solution of the Killing spinor equations of the heterotic
supergravity. In addition, we describe the classification of all half
supersymmetric solutions.


title:
On 3d N=8 Lorentzian BLG theory as a scaling limit of 3d superconformal
  N=6 ABJM theory

abstract:
  We elaborate on the suggestion made in arXiv:0806.3498 that the 3d \N=8
superconformal SU(N) Chern-Simons-matter theory of Lorentzian
Bagger-Lambert-Gustavson type (L-BLG) can be obtained by a scaling limit
(involving sending the level k to infinity and redefining the fields) from the
\N=6 superconformal U(N)xU(N) Chern-Simons-matter theory of Aharony, Bergman,
Jafferis and Maldacena (ABJM). We show that to implement such a limit in a
consistent way one is to extend the ABJM theory by an abelian "ghost"
multiplet. The corresponding limit at the 3-algebra level also requires
extending the non-antisymmetric Bagger-Lambert 3-algebra underlying the ABJM
theory by a negative-norm generator. We draw analogy with similar scaling
limits discussed previously for bosonic Chern-Simons theory and comment on some
implications of this relation between the ABJM and L-BLG theories.


title: Distributive Lattices, Polyhedra, and Generalized Flow

abstract:
  A D-polyhedron is a polyhedron $P$ such that if $x,y$ are in $P$ then so are
their componentwise max and min. In other words, the point set of a
D-polyhedron forms a distributive lattice with the dominance order. We provide
a full characterization of the bounding hyperplanes of D-polyhedra.
  Aside from being a nice combination of geometric and order theoretic
concepts, D-polyhedra are a unifying generalization of several distributive
lattices which arise from graphs. In fact every D-polyhedron corresponds to a
directed graph with arc-parameters, such that every point in the polyhedron
corresponds to a vertex potential on the graph. Alternatively, an edge-based
description of the point set can be given. The objects in this model are dual
to generalized flows, i.e., dual to flows with gains and losses.
  These models can be specialized to yield some cases of distributive lattices
that have been studied previously. Particular specializations are: lattices of
flows of planar digraphs (Khuller, Naor and Klein), of $\alpha$-orientations of
planar graphs (Felsner), of c-orientations (Propp) and of $\Delta$-bonds of
digraphs (Felsner and Knauer). As an additional application we exhibit a
distributive lattice structure on generalized flow of breakeven planar
digraphs.


title: Precise asymptotic of eigenvalues of resonant quasilinear systems

abstract:
  In this work we study the sequence of variational eigenvalues of a system of
resonant type involving $p-$ and $q-$laplacians on $\Omega \subset \R^N$, with
a coupling term depending on two parameters $\alpha$ and $\beta$ satisfying
$\alpha/p + \beta/q = 1$. We show that the order of growth of the $k^{th}$
eigenvalue depends on $\alpha+\beta$, $\lam_k = O(k^{\frac{\alpha+\beta}{N}})$.


title:
Feedback and Fluctuations in a Totally Asymmetric Simple Exclusion
  Process with Finite Resources

abstract:
  We revisit a totally asymmetric simple exclusion process (TASEP) with open
boundaries and a global constraint on the total number of particles [Adams, et.
al. 2008 J. Stat. Mech. P06009]. In this model, the entry rate of particles
into the lattice depends on the number available in the reservoir. Thus, the
total occupation on the lattice feeds back into its filling process. Although a
simple domain wall theory provided reasonably good predictions for Monte Carlo
simulation results for certain quantities, it did not account for the
fluctuations of this feedback. We generalize the previous study and find
dramatically improved predictions for, e.g., the density profile on the lattice
and provide a better understanding of the phenomenon of "shock localization."


title: Jet physics at HERA, Tevatron and LHC

abstract:
  In this short report, we discuss the Jet Physics results and perspectives at
HERA, Tevatron and LHC.


title: On interchanging the states of a pair of qudits

abstract:
  The qubit SWAP gate has been shown to be an integral component of quantum
circuitry design. It permutes the states of two qubits and allows for the
storage quantum information, teleportation of atomic or ionic states, and is a
fundamental element in the circuit implementation of Shor's algorithm. We
consider the problem of generalising the SWAP gate beyond the qubit setting. We
show that quantum circuit architectures completely described by instances of
the CNOT gate can not implement a transposition of a pair of qudits for
dimensions $d \equiv 3 (mod 4)$. The task of constructing generalised SWAP
gates based on transpositions of qudit states is argued in terms of the
signature of a permutation.


title:
Energy-scale phenomenology and pairing via resonant spin-charge motion
  in FeAs, CuO, heavy-fermion and other exotic superconductors

abstract:
  Muon spin relaxation ($\mu$SR) studies of the "1111" and "122" FeAs systems
have detected static magnetism with variably sized ordered moments in their
parent compounds. The phase diagrams of FeAs, CuO, organic BEDT,
A$_{3}$C$_{60}$ and heavy-fermion systems indicate competition between static
magnetism and superconductivity, associated with first-order phase transitions
at quantum phase boundaries. In both FeAs and CuO systems, the superfluid
density $n_{s}/m^{*}$ at $T \to 0$ exhibits a nearly linear scaling with
$T_{c}$. Analogous to the roton-minimum energy scaling with the lambda
transition temperature in superfluid $^{4}$He, clear scaling with $T_{c}$ was
also found for the energy of the magnetic resonance mode in cuprates,
(Ba,K)Fe$_{2}$As$_{2}$, CeCoIn$_{5}$ and CeCu$_{2}$Si$_{2}$, as well as the
energy of the superconducting coherence peak observed by angle resolved photo
emission (ARPES) in the cuprates near ($\pi$,0). Both the superfluid density
and the energy of these pair-non-breaking soft-mode excitations determine the
superconducting $T_{c}$ via phase fluctuations of condensed bosons. Combining
these observations and common dispersion relations of spin and charge
collective excitations in the cuprates, we propose a resonant spin charge
motion/coupling, "traffic-light resonance," expected when the charge energy
scale $\epsilon_{F}$ becomes comparable to the spin fluctuation energy scale
$\hbar\omega_{SF}\sim J$, as the process which leads to pair formation in these
correlated electron superconductors.


title: On distribution of fractional parts of linear forms

abstract:
  We prove a result on linear forms related to Peres-Schlag's theorem on badly
approximable numbers with respect to lacunary sequences.


title: Geometro-thermodynamics of tidal charged black holes

abstract:
  Tidal charged spherically symmetric vacuum brane black holes are
characterized by their mass m and tidal charge q, an imprint of the
5-dimensional Weyl curvature. For q>0 they are formally identical to the
Reissner-Nordstr\"om black hole of general relativity. We study the
thermodynamics and thermodynamic geometries of tidal charged black holes and
discuss similarities and differences as compared to the Reissner-Nordstr\"om
black hole. As a similarity, we show that (for q>0) the heat capacity of the
tidal charged black hole diverges on a set of measure zero of the parameter
space, nevertheless both the regularity of the Ruppeiner metric and a
Poincar\'e stability analysis shows no phase transition at those points. The
thermodynamic state spaces being different indicates that the underlying
statistical models could be different. We find that the q<0 parameter range,
which enhances the localization of gravity on the brane, is thermodynamically
preferred. Finally we constrain for the first time the possible range of the
tidal charge from the thermodynamic limit on gravitational radiation efficiency
at black hole mergers.


title: The space of subgroups of an abelian group

abstract:
  We carry out the Cantor-Bendixson analysis of the space of all subgroups of
any countable abelian group and we deduce a complete classification of such
spaces up to homeomorphism.


title:
Suppression or enhancement of the Fulde-Ferrell-Larkin-Ovchinnikov order
  in a one-dimensional optical lattice with particle correlated tunnelling

abstract:
  We study through controlled numerical simulation the ground state properties
of spin-polarized strongly interacting fermi gas in an anisotropic optical
lattice, which is described by an effective one-dimensional general Hubbard
model with particle correlated hopping rate. We show that the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) type of state, while enhanced by a
negative correlated hopping rate, can be completely suppressed by positive
particle correlated hopping, yielding to an unusual magnetic phase even for
particles with on-site attractive interaction We also find several different
phase separation patterns for these atoms in an inhomogeneous harmonic trap,
depending on the correlated hopping rate.


title: Maximal Levi Subgroups Acting on the Building of GL_n(F)

abstract:
  In this paper we give a complete invariant of the action of GL_n(F)\times
GL_m(F) acting on the Euclidean building B[GL_n(F)], where F is a
non-archimedian field. We then use this invariant to give a natural metric on
the resulting quotient space. In the special case of the torus acting on
B[GL_2(F)] this gives a method of calculating of any vertex to any fixed
apartment.


title:
On the nature of HESS J1503-582 revealed by the H.E.S.S. experiment:
  Coincidence with a FVW?

abstract:
  The H.E.S.S. survey of the inner Galaxy in the very-high-energy gamma-ray
domain has led to the discovery of many extended sources, some of which do not
appear to be associated with any obvious counterpart at traditional wavelengths
(radio, infrared and X-ray). In this contribution, preliminary H.E.S.S. results
on one of these so-called "dark" sources, namely HESS J1503-582, are presented.
After introducing the properties of this source candidate, results of the
search for counterparts in several astronomical windows are shown. Finally, its
possible association with a "Forbidden-Velocity-Wing", a characteristic 21 cm
HI line structure that appears as a deviation from the canonical Galactic
rotation curve, is discussed.


title:
The Distribution of Fst and other Genetic Statistics for a Class of
  Population Structure Models

abstract:
  We examine genetic statistics used in the study of structured populations. In
a 1999 paper, Wakeley observed that the coalescent process associated with the
finite island model can be decomposed into a scattering phase and a collecting
phase. In this paper, we introduce a class of population structure models,
which we refer to as G/KC models, that obey such a decomposition. In a large
population, large sample limit we derive the distribution of the statistic Fst
for all G/KC models under the assumptions of strong or weak mutation. We show
that in the large population, large sample limit the island and two dimensional
stepping stone models are members of the G/KC class of models, thereby deriving
the distributions of Fst for these two well known models as a special case of a
general formula. We show that our analysis of Fst can be extended to an entire
class of genetic statistics, and we use our approach to examine homozygosity
measures. Our analysis uses coalescent based methods.


title: Galaxies appear simpler than expected

abstract:
  Galaxies are complex systems the evolution of which apparently results from
the interplay of dynamics, star formation, chemical enrichment, and feedback
from supernova explosions and supermassive black holes. The hierarchical theory
of galaxy formation holds that galaxies are assembled from smaller pieces,
through numerous mergers of cold dark matter. The properties of an individual
galaxy should be controlled by six independent parameters including mass,
angular-momentum, baryon-fraction, age and size, as well as by the accidents of
its recent haphazard merger history. Here we report that a sample of galaxies
that were first detected through their neutral hydrogen radio-frequency
emission, and are thus free of optical selection effects, shows five
independent correlations among six independent observables, despite having a
wide range of properties. This implies that the structure of these galaxies
must be controlled by a single parameter, although we cannot identify this
parameter from our dataset. Such a degree of organisation appears to be at odds
with hierarchical galaxy formation, a central tenet of the cold dark matter
paradigm in cosmology.


title: Decaying Dark Matter and the PAMELA Anomaly

abstract:
  Astrophysical and cosmological observations do not require the dark matter
particles to be absolutely stable. If they are indeed unstable, their decay
into positrons might occur at a sufficiently large rate to allow the indirect
detection of dark matter through an anomalous contribution to the cosmic
positron flux. In this paper we discuss the implications of the excess in the
positron fraction recently reported by the PAMELA collaboration for the
scenario of decaying dark matter. To this end, we have performed a
model-independent analysis of possible signatures by studying various decay
channels in the case of both a fermionic and a scalar dark matter particle. We
find that the steep rise in the positron fraction measured by PAMELA at
energies larger than 10 GeV can naturally be accommodated in several
realizations of the decaying dark matter scenario.


title: Colossal dielectric constant up to GHz at room temperature

abstract:
  The search for new materials with extremely high ("colossal") dielectric
constants, required for future electronics, is one of the most active fields of
modern materials science. However, the applicability of the colossal-epsilon'
materials, discovered so far, suffers from the fact that their dielectric
constant, epsilon', only is huge in a limited frequency range below about 1
MHz. In the present report, we show that the dielectric properties of
La15/8Sr1/8NiO4 surpass those of other materials. Especially, epsilon' retains
its colossal magnitude of >10000 well into the GHz range. This material is
prone to charge order and this spontaneous ordering process of the electronic
subsystem can be assumed to play an important role in the generation of the
observed unusual dielectric properties.


title: A Catalog of 24um Sources Toward the Galactic Center

abstract:
  We present a 1.5deg x 8deg (220pc x 1195pc) Multiband Imaging Photometer for
Spitzer 24um image of the Galactic Center and an accompanying point source
list. This image is the highest spatial resolution (6" ~ 0.25pc) and
sensitivity map ever taken across the GC at this wavelength, showing the
emission by warm dust in unprecedented detail. Over 120,000 point sources are
identified in this catalog with signal-to-noise ratios greater than five and
flux densities from 0.6mJy to 9Jy.


title: Symmetry Energy in Nuclear Surface

abstract:
  Interplay between the dependence of symmetry energy on density and the
variation of nucleonic densities across nuclear surface is discussed. That
interplay gives rise to the mass dependence of the symmetry coefficient in an
energy formula. Charge symmetry of the nuclear interactions allows to introduce
isoscalar and isovector densities that are approximately independent of the
magnitude of neutron-proton asymmetry.


title: Pulsar Wind Nebula candidates recently discovered by H.E.S.S

abstract:
  H.E.S.S. is currently the most sensitive instrument in the very-high-energy
gamma-ray domain and has revealed many new sources along the Galactic Plane, a
significant fraction of which seems to be associated with energetic pulsars.
HESS J1825-137 and Vela X are considered to be the prototypes of such sources
in which the large VHE nebula results from the whole history of the pulsar wind
and the supernova remnant host, both evolving in a complex interstellar medium.
These nebulae are seen to be offset from the pulsar position and, for HESS
J1825-137, a spectral steepening at increasing distance from the pulsar has
been measured. In this context, updated H.E.S.S. results on two previously
published sources, namely HESS J1809-193 and HESS J1912+101, and preliminary
results on the newly discovered HESS J1356-645, are presented. These extended
VHE sources are thought to be associated with the energetic pulsars PSR
J1809-1917, PSR J1913+1011 and PSR J1357-6429, respectively. Properties of each
source in the VHE regime, together with those measured in the radio and X-ray
domains, are discussed.


title:
Flesh and Blood, or Merely Ghosts? Some Comments on the Multi-Muon Study
  at CDF

abstract:
  A recent paper by the CDF collaboration suggests (but does not claim) an
anomalous event sample containing muons produced with large impact parameter,
often with high multiplicity and at small angles from one another. This curious
hint of a signal is potentially consistent with the hidden valley scenario, as
well as with some other classes of models. Despite its tenuous nature, this
hint highlights the experimental difficulties raised by such signals, and
merits some consideration. Some of the simplest interpretations of the data,
such as a light neutral particle decaying to muon and/or tau pairs, are largely
disfavored; three-body decays to $\tau\tau\nu$ appear slightly better. An
alternative speculative possibility -- a "micro-cascade decay" -- might be
consistent with the data. It is suggested that the experimentalists involved
provide additional plots showing invariant mass distributions of same- and
opposite-sign dimuon pairs, invariant masses of various classes of displaced
vertices, and spatial correlations among vertices within a cone.


title:
Time Series Technical Analysis via New Fast Estimation Methods: A
  Preliminary Study in Mathematical Finance

abstract:
  New fast estimation methods stemming from control theory lead to a fresh look
at time series, which bears some resemblance to "technical analysis". The
results are applied to a typical object of financial engineering, namely the
forecast of foreign exchange rates, via a "model-free" setting, i.e., via
repeated identifications of low order linear difference equations on sliding
short time windows. Several convincing computer simulations, including the
prediction of the position and of the volatility with respect to the forecasted
trendline, are provided. $\mathcal{Z}$-transform and differential algebra are
the main mathematical tools.

categories: stat.AP math.AC math.OC math.ST q-fin.CP q-fin.TR stat.TH


title:
High-velocity neon line emission from the ULIRG IRAS F00183-7111:
  revealing the optically obscured base of a nuclear outflow

abstract:
  We report the first mid-IR detection of highly disturbed ionized gas in the
ultraluminous infrared galaxy IRAS F00183-7111. The gas, traced by the 12.81um
[NeII] and 15.56um [NeIII] lines, spans a velocity range of-3500 to 3000 km/s
with respect to systemic velocity. Optical and near-IR spectroscopic studies
show no evidence for similarly high velocity gas components in forbidden lines
at shorter wavelengths. We interpret this as the result of strong extinction
(Av=10-50) on the high-velocity gas, which identifies the base of the outflow
traced in 5007A [OIII] as a plausible origin. Unusual excitation conditions are
implied by a comparison of the mid-infrared low-excitation neon line emission
and the PAH emission for a sample of 56 ULIRGs. For IRAS F00183, the neon/PAH
ratio is 8 times higher than the average ratio. Similar mid-infrared kinematic
and excitation characteristics are found for only 2 other ULIRGs in our sample:
IRAS 12127-1412NE and IRAS 13451+1232. Both sources have an elevated neon/PAH
ratio and exhibit pronounced blue wings in their 15.56um [NeIII] line profiles.
IRAS 13451 even shows a strongly blue shifted and broad 14.32um [NeV] line.
While for IRAS 13451 the observed [NeIII]/[NeII] and [NeV]/[NeII] line ratios
indicate exposure of the blue shifted gas to direct radiation from the AGN, for
IRAS F00183 and 12127 the neon line ratios are consistent with an origin in
fast shocks in a high-density environment, and with an evolutionary scenario in
which strongly blue shifted [Ne II] and [Ne III] emission trace the (partial)
disruption of the obscuring medium around a buried AGN. The detection of
strongly blue shifted [Ne V] emission in IRAS 13451 would then indicate this
process to be much further advanced in this ULIRG than in IRAS F00183 and
12127, where this line is undetected.


title: Remarks on the tunneling limit of strong-field photoionization

abstract:
  Some results from a recent work of Reiss [Phys. Rev. Lett. 101, 043002
(2008); 101, 159901(E) (2008).] are generalized for the case of elliptical
polarization of a laser field. We also discuss the tunneling limit of
strong-field photoionization.


title: On the zero set of G-equivariant maps

abstract:
  Let $G$ be a finite group acting on vector spaces $V$ and $W$ and consider a
smooth $G$-equivariant mapping $f:V\to W$. This paper addresses the question of
the zero set near a zero $x$ of $f$ with isotropy subgroup $G$. It is known
from results of Bierstone and Field on $G$-transversality theory that the zero
set in a neighborhood of $x$ is a stratified set. The purpose of this paper is
to partially determine the structure of the stratified set near $x$ using only
information from the representations $V$ and $W$. We define an index
$s(\Sigma)$ for isotropy subgroups $\Sigma$ of $G$ which is the difference of
the dimension of the fixed point subspace of $\Sigma$ in $V$ and $W$. Our main
result states that if $V$ contains a subspace $G$-isomorphic to $W$, then for
every maximal isotropy subgroup $\Sigma$ satisfying $s(\Sigma)>s(G)$, the zero
set of $f$ near $x$ contains a smooth manifold of zeros with isotropy subgroup
$\Sigma$ of dimension $s(\Sigma)$. We also present a systematic method to study
the zero sets for group representations $V$ and $W$ which do not satisfy the
conditions of our main theorem. The paper contains many examples and raises
several questions concerning the computation of zero sets of equivariant maps.
These results have application to the bifurcation theory of $G$-reversible
equivariant vector fields.


title: Birkhoff's theorem fails to save MOND from non-local physics

abstract:
  We investigate the consequences of Birkhoff's theorem in general relativity
(GR) and in Modified Newtonian dynamics (MOND). We study, in particular, the
system of a finite-mass test particle inside a spherical shell. In both GR and
MOND, we find non-vanishing acceleration for that test particle. The direction
of the acceleration is such that it pushes the test particle toward the center
of the shell. In GR, the acceleration is found analytically in the case of a
small test mass with a small displacement from the center of the shell. In
MOND, the acceleration is found analytically in the limit of large test mass
and small displacement, and a comparison to numerical values is made. Numerical
simulations are done for more general cases with parameters that mimic the
system of a galaxy in a cluster. In GR, the acceleration is highly suppressed,
and physically insignificant. In MOND, on the contrary, the acceleration of the
point particle can be a significant fraction of the field just outside of the
spherical shell.


title:
The complete AdS(4) x CP(3) superspace for the type IIA superstring and
  D-branes

abstract:
  We lift the bosonic AdS_4 x CP^3 solution of type IIA supergravity preserving
24 supersymmetries to a D=10 superspace which has 32 Grassmann-odd directions.
The type IIA superspace is obtained from D=11 via dimensional reduction of the
coset superspace OSp(8|4)/SO(7) x SO(1,3) by realizing the latter as a Hopf
fibration over the former. This construction generalizes to superspace the Hopf
fibration of S^7 as a U(1) bundle over CP^3, and is suitable for writing the
explicit form of Green-Schwarz-type actions encoding the dynamics of the type
IIA string and branes in the AdS_4 x CP^3 superbackground. We show that the
OSp(6|4)/U(3) x SO(1,3) supercoset string action describes only a subsector of
the complete Green-Schwarz superstring. Thus, even though the superstring
equations of motion in the OSp(6|4)/U(3) x SO(1,3) subsector are classically
integrable, the fact that the full AdS_4 x CP^3 superspace is not a supercoset
requires the use of more general methods to determine whether the superstring
in the complete AdS_4 x CP^3 superbackground is classically integrable.


title: Invariant Hilbert schemes and Wonderful varieties

abstract:
  The invariant Hilbert schemes considered in \cite{BC1} were proved to be
affine spaces. The proof relied on the classification of strict wonderful
varieties. We obtain in the present article a classification-free proof of the
affinity of these invariant Hilbert scheme by means of deformation theoretical
arguments. As a consequence we recover in a shorter way the classification of
strict wonderful varieties. This provides an alternative and new approach to
answer Luna's conjecture.


title:
Superintegrability with third order integrals of motion, cubic algebras
  and supersymmetric quantum mechanics II:Painleve transcendent potentials

abstract:
  We consider a superintegrable quantum potential in two-dimensional Euclidean
space with a second and a third order integral of motion. The potential is
written in terms of the fourth Painleve transcendent. We construct for this
system a cubic algebra of integrals of motion. The algebra is realized in terms
of parafermionic operators and we present Fock type representations which yield
the corresponding energy spectra. We also discuss this potential from the point
of view of higher order supersymmetric quantum mechanics and obtain ground
state wave functions.


title: Kac's conjecture from Nakajima quiver varieties

abstract:
  We prove a generating function formula for the Betti numbers of Nakajima
quiver varieties. We prove that it is a q-deformation of the Weyl-Kac character
formula. In particular this implies that the constant term of the polynomial
counting the number of absolutely indecomposable representations of a quiver
equals the multiplicity of a a certain weight in the corresponding Kac-Moody
algebra, which was conjectured by Kac in 1982.


title: Constructions of Subsystem Codes over Finite Fields

abstract:
  Subsystem codes protect quantum information by encoding it in a tensor factor
of a subspace of the physical state space. Subsystem codes generalize all major
quantum error protection schemes, and therefore are especially versatile. This
paper introduces numerous constructions of subsystem codes. It is shown how one
can derive subsystem codes from classical cyclic codes. Methods to trade the
dimensions of subsystem and co-subystem are introduced that maintain or improve
the minimum distance. As a consequence, many optimal subsystem codes are
obtained. Furthermore, it is shown how given subsystem codes can be extended,
shortened, or combined to yield new subsystem codes. These subsystem code
constructions are used to derive tables of upper and lower bounds on the
subsystem code parameters.


title: Transport Coefficients of Hadronic Matter near $T_c$

abstract:
  A hadron resonance gas model including all known particles and resonances
with masses $m<2$ GeV and an exponentially rising density of Hagedorn states
for $m>2$ GeV is used to obtain an upper bound on the shear viscosity to
entropy density ratio, $\eta/s\approx1/(4\pi)$, of hadronic matter near $T_c$.
We found a large trace anomaly and small speed of sound near $T_c$, which agree
well with recent lattice calculations. We comment on the bulk viscosity to
entropy density ratio close to $T_c$.


title:
Gauge invariant cosmological perturbation equations with corrections
  from loop quantum gravity

abstract:
  A consistent implementation of quantum gravity is expected to change the
familiar notions of space, time and the propagation of matter in drastic ways.
This will have consequences on very small scales, but also gives rise to
correction terms in evolution equations of modes relevant for observations. In
particular, the evolution of inhomogeneities in the very early universe should
be affected. In this paper consistent evolution equations for gauge-invariant
perturbations in the presence of inverse triad corrections of loop quantum
gravity are derived. Some immediate effects are pointed out, for instance
concerning conservation of power on large scales and non-adiabaticity. It is
also emphasized that several critical corrections can only be seen to arise in
a fully consistent treatment where the gauge freedom of canonical gravity is
not fixed before implementing quantum corrections. In particular, metric modes
must be allowed to be inhomogeneous: it is not consistent to assume only matter
inhomogeneities on a quantum corrected homogeneous background geometry. In this
way, stringent consistency conditions arise for possible quantization
ambiguities which will eventually be further constrained observationally.


title: A Model for the Pioneer Anomaly

abstract:
  In a previous work we showed that massive test particles exhibit a
non-geodesic acceleration in a modified theory of gravity obtained by a
non-commutative deformation of General Relativity (so-called Matrix Gravity).
We propose that this non-geodesic acceleration might be the origin of the
anomalous acceleration experienced by the Pioneer 10 and Pioneer 11
spacecrafts.


title:
The quiver of an algebra associated to the Mantaci-Reutenauer descent
  algebra and the homology of regular semigroups

abstract:
  We develop the homology theory of the algebra of a regular semigroup, which
is a particularly nice case of a quasi-hereditary algebra in good
characteristic. Directedness is characterized for these algebras, generalizing
the case of semisimple algebras studied by Munn and Ponizovksy. We then apply
homological methods to compute (modulo group theory) the quiver of a right
regular band of groups, generalizing Saliola's results for a right regular
band. Right regular bands of groups come up in the representation theory of
wreath products with symmetric groups in much the same way that right regular
bands appear in the representation theory of finite Coxeter groups via the
Solomon-Tits algebra of its Coxeter complex. In particular, we compute the
quiver of Hsiao's algebra, which is related to the Mantaci-Reutenauer descent
algebra.


title: Quantum Phase Transitions in the Hubbard Model on Triangular Lattice

abstract:
  We investigate the quantum phase transitions in the half-filled Hubbard model
on the triangular lattice by means of the path-integral renormalization group
(PIRG) method with a new iteration scheme proposed recently. It is found that
as the Hubbard interaction $U$ increases, the paramagnetic metallic state
undergoes a first-order phase transition to a nonmagnetic insulating (NMI)
state at $U_{c1}\sim 7.7t$, which is followed by another first-order transition
to a $120^\circ$ N\'eel ordered state at $U_{c2}\sim 10t$, where $t$ is the
transfer integral. Our results ensure the existence of the intermediate NMI
phase, and resolve some controversial arguments on the nature of the previously
proposed quantum phase transitions. We find that
$\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ is located in the NMI phase close to the
metal-insulator transition point.


title:
Highly ionized gas on galaxy scales: mapping the interacting Seyfert
  galaxy LEDA 135736

abstract:
  We have used the VIMOS IFU to map the properties of the Seyfert 1.9 galaxy
LEDA 135736. These maps reveal a number of interesting features including: an
Extended Narrow Line Region detectable out to 9 kpc, an area of intense star
formation located at a projected distance of 12 kpc from the centre, an
elliptical companion galaxy, and kinematic features, aligned along the
long-axis of the ENLR, that are consistent with radio jet-driven mass outflow.
We propose that the ENLR results from extra-planar gas ionized by the AGN, and
that the AGN in turn might be triggered by interaction with the companion
galaxy, which can also explain the burst of star formation and morphological
features. Only about two percent of the ENLR's kinetic energy is in the mass
outflow. We infer from this that the bulk of mechanical energy imparted by the
jet is used to heat this gas.


title:
Probing The Lower Mass Limit for Supernova Progenitors and the High-Mass
  End of the Initial-Final Mass Relation from White Dwarfs in the Open Cluster
  M35 (NGC 2168)

abstract:
  We present a photometric and spectroscopic study of the white dwarf
population of the populous, intermediate-age open cluster M35 (NGC 2168); this
study expands upon our previous study of the white dwarfs in this cluster. We
spectroscopically confirm 14 white dwarfs in the field of the cluster: 12 DAs,
1 hot DQ, and 1 DB star. For each DA, we determine the white dwarf mass and
cooling age, from which we derive the each star's progenitor mass. These data
are then added to the empirical initial-final mass relation (IFMR), where the
M35 WDs contribute significantly to the high-mass end of the relation. The
resulting points are consistent with previously-published linear fits to the
IFMR, modulo moderate systematics introduced by the uncertainty in the star
cluster age. Based on this cluster alone, the observational lower limit on the
maximum mass of white dwarf progenitors is found to be ~5.1-5.2 solar masses at
the 95% confidence level; including data from other young open clusters raises
this limit as high as 7.1 solar masses, depending on the cluster membership of
three massive WDs and the core-composition of the most massive WDs. We find
that the apparent distance modulus and extinction derived solely from the
cluster white dwarfs [(m-M)v=10.45 +/- 0.08 and E(B-V)=0.185 +/- 0.010,
respectively] is fully consistent with that derived from main-sequence fitting
techniques. Four M35 WDs may be massive enough to have oxygen-neon cores; the
assumed core composition does not significantly affect the empirical IFMR.
Finally, the two non-DA WDs in M35 are photometrically consistent with cluster
membership; further analysis is required to determine their memberships.


title: Time-resolved spectral correlations of long-duration Gamma-Ray Bursts

abstract:
  For a sample of long GRBs with known redshift, we study the distribution of
the evolutionary tracks on the rest-frame luminosity-peak energy Liso-Ep'
diagram. We are interested in exploring the extension of the `Yonetoku'
correlation to any phase of the prompt light curve, and in verifying how the
high-signal prompt duration time, Tf, in the rest frame correlates with the
residuals of such correlation (Firmani et al. 2006). For our purpose, we
analyse separately two samples of time-resolved spectra corresponding to 32
GRBs with peak fluxes >1.8 phot cm^-2 s^-1 from the Swift-BAT detector, and 7
bright GRBs from the CGRO-BATSE detector previously processed by Kaneko et al.
(2006). After constructing the Liso-Ep' diagram, we discuss the relevance of
selection effects, finding that they could affect significantly the
correlation. However, we find that these effects are much less significant in
the Liso x Tf-Ep' diagram, where the intrinsic scatter reduces significantly.
We apply further corrections for reducing the intrinsic scatter even more. For
the sub-samples of GRBs (7 from Swift and 5 from CGRO) with measured jet break
time, we analyse the effects of correcting Liso by jet collimation. We find
that (i) the scatter around the correlation is reduced, and (ii) this scatter
is dominated by the internal scatter of the individual evolutionary tracks.
These results suggest that the time, integrated `Amati' and `Ghirlanda'
correlations are consequences of the time resolved features, not of selection
effects, and therefore call for a physical origin. We finally remark the
relevance of looking inside the nature of the evolutionary tracks.


title: The Signature of Galactic Tides in Local Group Dwarf Spheroidals

abstract:
  (Abridged) We use N-body simulations to explore the effects of tidal
stripping on the structure of dwarf spheroidal galaxies (dSphs). We model dSphs
as King spheres embedded in NFW dark halos that orbit the Galactic potential on
eccentric orbits. We find that episodes of stellar mass loss remove the initial
cutoff of the bound stellar core. Once equilibrium has been re-established the
outer mass profile approaches a power-law in projection that is well described
by a simple Plummer model. Tides also result in transient features in the outer
density profile. As the system re-equilibrates, an outward-moving "excess" of
stars is found at radii where the local crossing time exceeds the time elapsed
since pericenter. If the orbit is known, these results provide a simple way to
assess whether "breaks" and "bumps" in the profile of dSphs are actually tidal
in origin. We apply this to the Sagittarius dwarf and, encouragingly, identify
two features in the profile that may be traced to its two last pericentric
passages. Applied to Leo I, we find that any tidal break would locate beyond
the area surveyed by current data, casting doubt on recent claims of the
detection of tidal debris around this galaxy. For Carina, the tidal break
should occur at a radius twice farther than observed, suggesting that the outer
excess of stars is not tidal in origin unless its orbit is in error. A similar
comment applies to Sculptor, whose pericenter appears too large for Galactic
tides to be important but whose outer profile, like that of Draco, nonetheless
follows closely a Plummer-law. Fornax and Leo II show no sign of a power-law
outer profile, suggesting that they have not suffered stellar tidal stripping.
Published profiles for other, fainter Milky Way dSph companions do not extend
sufficiently far to allow for conclusive assessment.


title: p-brane dynamics in N+1-dimensional FRW universes

abstract:
  We study the evolution of maximally symmetric $p$-branes with a
$S_{p-i}\otimes \mathbbm{R}^i$ topology in flat expanding or collapsing
homogeneous and isotropic universes with $N+1$ dimensions (with $N \ge 3$, $p <
N$, $0 \le i < p$). We find the corresponding equations of motion and compute
new analytical solutions for the trajectories in phase space. For a constant
Hubble parameter, $H$, and $i=0$ we show that all initially static solutions
with a physical radius below a certain critical value, $r_c^0$, are periodic
while those with a larger initial radius become frozen in comoving coordinates
at late times. We find a stationary solution with constant velocity and
physical radius, $r_c$, and compute the root mean square velocity of the
periodic $p$-brane solutions and the corresponding (average) equation of state
of the $p$-brane gas. We also investigate the $p$-brane dynamics for $H \neq
{\rm constant}$ in models where the evolution of the universe is driven by a
perfect fluid with constant equation of state parameter, $w={\cal P}_p/\rho_p$,
and show that a critical radius, $r_c$, can still be defined for $ -1 \le w <
w_c$ with $w_c=(2-N)/N$. We further show that for $w \sim w_c$ the critical
radius is given approximately by $r_c H \propto (w_c-w)^{\gamma_c}$ with
$\gamma_c=-1/2$ ($r_c H \to \infty$ when $w \to w_c$). Finally, we discuss the
impact that the large scale dynamics of the universe can have on the
macroscopic evolution of very small loops.


title:
Spitzer Observations of L429: A Near-collapse or Collapsing Starless
  Core

abstract:
  We present Spitzer infrared observations of the starless core L429. The IR
images of this core show an absorption feature, caused by the dense core
material, at wavelengths <= 70 micron. The core has a steep density profile,
and reaches A_V > 35 mag near the center. We show that L429 is either
collapsing or in a near-collapse state.


title:
Hierarchical Phase Space Structure of Dark Matter Haloes: Tidal debris,
  Caustics, and Dark Matter annihilation

abstract:
  Most of the mass content of dark matter haloes is expected to be in the form
of tidal debris. The density of debris is not constant, but rather can grow due
to formation of caustics at the apocenters and pericenters of the orbit, or
decay as a result of phase mixing. In the phase space, the debris assemble in a
hierarchy which is truncated by the primordial temperature of dark matter.
Understanding this phase structure can be of significant importance for the
interpretation of many astrophysical observations and in particular dark matter
detection experiments. With this purpose in mind, we develop a general
theoretical framework to describe the hierarchical structure of the phase space
of cold dark matter haloes. We do not make any assumption of spherical symmetry
and/or smooth and continuous accretion. Instead, working with correlation
functions in the action-angle space, we can fully account for the hierarchical
structure (predicting a two-point correlation function ~ (\Delta J)^{-1.6} in
the action space), as well as the primordial discreteness of the phase space.
As an application, we estimate the boost to the dark matter annihilation signal
due to the structure of the phase space within virial radius: the boost due to
the hierarchical tidal debris is of order unity, whereas the primordial
discreteness of the phase structure can boost the total annihilation signal by
up to an order of magnitude. The latter is dominated by the regions beyond 20%
of the virial radius, and is largest for the recently formed haloes with the
least degree of phase mixing.


title: Stringy Instantons and Yukawa Couplings in MSSM-like Orientifold Models

abstract:
  Type IIA orientifold constructions with intersecting D6-branes and their IIB
duals in terms of magnetized D9/D7-branes constitute one of the most promising
avenues for the construction of semirealistic MSSM-like compactifications. One
generic problem with these constructions is, that there are many Yukawa
couplings, which vanish due to additional U(1) symmetries in the theory. In
this paper we consider a number of such settings and study, under what
conditions stringy instanton effects can give rise to non-perturbative
contributions to the Yukawa couplings, so that all perturbatively forbidden
terms are induced. We find specific settings, in which indeed Yukawa couplings
for all fermions are obtained. For some cases we provide specific local
examples of rigid O(1) Instantons within the T^6/ Z2 x Z2' toroidal orientifold
with torsion, giving rise to the required amplitudes. A potential problem in
these settings is, that the same instantons, providing for Yukawa coupling
contributions, may give rise to too large mu-terms for the Higgs multiplets. We
show how this problem may be overcome in explicit models with a doubled Higgs
system.


title: The multivariate signed Bollobas-Riordan polynomial

abstract:
  We generalise the signed Bollobas-Riordan polynomial of S. Chmutov and I. Pak
[Moscow Math. J. 7 (2007), no. 3, 409-418] to a multivariate signed polynomial
Z and study its properties. We prove the invariance of Z under the recently
defined partial duality of S. Chmutov [J. Combinatorial Theory, Ser. B, 99 (3):
617-638, 2009] and show that the duality transformation of the multivariate
Tutte polynomial is a direct consequence of it.


title:
Imaging nanoscale Fermi surface variations in an inhomogeneous
  superconductor

abstract:
  Particle-wave duality suggests we think of electrons as waves stretched
across a sample, with wavevector k proportional to their momentum. Their
arrangement in "k-space," and in particular the shape of the Fermi surface,
where the highest energy electrons of the system reside, determine many
material properties. Here we use a novel extension of Fourier transform
scanning tunneling microscopy to probe the Fermi surface of the strongly
inhomogeneous Bi-based cuprate superconductors. Surprisingly, we find that
rather than being globally defined, the Fermi surface changes on nanometer
length scales. Just as shifting tide lines expose variations of water height,
changing Fermi surfaces indicate strong local doping variations. This
discovery, unprecedented in any material, paves the way for an understanding of
other inhomogeneous characteristics of the cuprates, like the pseudogap
magnitude, and highlights a new approach to the study of nanoscale
inhomogeneity in general.


title: Potential automorphy for certain Galois representations to GL_2n

abstract:
  Building upon work of Clozel, Harris, Shepherd-Barron, and Taylor, this paper
shows that certain Galois representations become automorphic after one makes a
suitably large totally-real extension to the base field. The main innovation
here is that the result applies to Galois representations to GL_{2n}, where
previous work dealt with representations to GSp_n. The main technique is the
consideration of the cohomology the Dwork hypersurface, and in particular, of
pieces of this cohomology other than the invariants under the natural group
action.


title: Spectral measure of heavy tailed band and covariance random matrices

abstract:
  We study the asymptotic behavior of the appropriately scaled and possibly
perturbed spectral measure $\mu$ of large random real symmetric matrices with
heavy tailed entries. Specifically, consider the N by N symmetric matrix
$Y_N^\sigma$ whose (i,j) entry is $\sigma(i/N,j/N)X_{ij}$ where $(X_{ij},
0<i<j+1<\infty)$ is an infinite array of i.i.d real variables with common
distribution in the domain of attraction of an $\alpha$-stable law,
$0<\alpha<2$, and $\sigma$ is a deterministic function. For a random diagonal
$D_N$ independent of $Y_N^\sigma$ and with appropriate rescaling $a_N$, we
prove that the distribution $\mu$ of $a_N^{-1}Y_N^\sigma + D_N$ converges in
mean towards a limiting probability measure which we characterize. As a special
case, we derive and analyze the almost sure limiting spectral density for
empirical covariance matrices with heavy tailed entries.


title: Meromorphic continuation for the zeta function of a Dwork hypersurface

abstract:
  We consider the one-parameter family of hypersurfaces in $\Pj^5$ with
projective equation (X_1^5+X_2^5+X_3^5+X_4^5+X_5^5) = 5\lambda X_1 X_2... X_5,
(writing $\lambda$ for the parameter), proving that the Galois representations
attached to their cohomologies are potentially automorphic, and hence that the
zeta function of the family has meromorphic continuation throughout the complex
plane.


title: Low-mass scalar production in $\gamma \gamma$ scattering

abstract:
  We estimate the I=0 scalar meson $\sigma/f_0(600)$ $\gamma\gamma$ widths,
from $\pi\pi$ and $\gamma\gamma$ scattering data below 700 MeV using an
improved analytic K-matrix model.


title: A Mixed Tau-Electroproduction Sum Rule for V_us

abstract:
  The interpretation of results of recent tau decay determinations of |V_us|,
which yield values ~3 sigma low compared to 3-family unitarity expectations, is
complicated by the slow convergence of the relevant integrated D=2 OPE series.
We introduce a class of sum rules involving both electroproduction and tau
decay data designed to deal with this problem by strongly suppressing D=2 OPE
contributions at the correlator level. Experimental complications are briefly
discussed and an example of the improved control over theoretical errors
presented. The uncertainty on the resulting determination, |V_{us}|
=0.2202(39), is entirely dominated by experimental errors, and should be
subject to significant near-term improvement.


title:
Constraining the star formation histories of GRB Host Galaxies from
  their observed abundance patterns

abstract:
  Long-duration Gamma Ray Bursts (GRBs) are linked to the collapse of massive
stars and their hosts are exclusively identified as active, star forming
galaxies. Four long GRBs observed at high spectral resolution at redshift 1.5
<z < 4 allowed the determination of the elemental abundances for a set of
different chemical elements. In this paper, for the first time, by means of
detailed chemical evolution models taking into account also dust production, we
attempt to constrain the star formation history of the host galaxies of these
GRBs from the study of the chemical abundances measured in their ISM. We are
also able to provide constraints on the age and on the dust content of GRB
hosts. Our results support the hypothesis that long duration GRBs occur
preferentially in low metallicity, star forming galaxies. We compare the
specific star formation rate, namely the star formation rate per unit stellar
mass, predicted for the hosts of these GRBs with observational values for GRB
hosts distributed across a large redshift range. Our models predict a decrease
of the specific star formation rate (SSFR) with redshift, consistent with the
observed decrease of the comoving cosmic SFR density between z ~2 and z=0. On
the other hand, observed GRB hosts seems to follow an opposite trend in the
SSFR vs redshift plot, with an increase of the SSFR with decreasing redshift.
Finally, we compare the SSFR of GRB050730 host with values derived for a sample
of Quasar damped Lyman alpha systems. Our results indicate that the abundance
pattern and the specific star formation rates of the host galaxies of these
GRBs are basically compatible with the ones determined in Quasar damped Lyman
alpha systems, suggesting similar chemical evolution paths.


title:
Simulation Study of Chic -> J/Psi + gamma Detection with J/Psi -> e+ e-
  in pp Collisions

abstract:
  We present Monte Carlo preliminary results about the feasibility to detect
the Chic family in p-p collisions at 14 TeV in the ALICE Central Barrel at CERN
LHC. The Chic1 and Chic2 were forced to decay in the channel J/Psi + gamma ->
e+ e- + gamma and were merged with a proton-proton non-biased collision. After
MonteCarlo transport and simulation of the detector response, the e+, e- and
converted gamma were reconstructed and identified in the ALICE ITS, TPC and TRD
detectors. Separate signals corresponding to gamma from Chic1 and from Chic2
were observed. The position and relative weight of the fit to gaussians agreed
with the input values within the statistical limits. Similar studies will be
done for Pb-Pb collisions.


title: A note on the Busemann-Petty problem for bodies of certain invariance

abstract:
  The Busemann-Petty problem asks whether origin symmetric convex bodies in
$\R^n$ with smaller hyperplane sections necessarily have smaller volume. The
answer is affirmative if $n\leq 3$ and negative if $n\geq 4.$ We consider a
class of convex bodies that have a certain invariance property with respect to
their ordered k-tuples of coordinates in $\R^{kn}$ and prove the corresponding
problem.


title:
The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray
  source

abstract:
  We present an analysis of the extreme obscuration variability observed during
an XMM-Newton 5-days continuous monitoring of the AGN in NGC 1365. The source
was in a reflection-dominated state in the first ~1.5 days, then a strong
increase of the 7-10 keV emission was observed in ~10 hours, followed by a
symmetric decrease. The spectral analysis of the different states clearly shows
that this variation is due to an uncovering of the X-ray source. From this
observation we estimate a size of the X-ray source D_S<10^13 cm, a distance of
the obscuring clouds R~10^16 cm and a density n~10^11 cm^{-3}. These values
suggest that the X-ray absorption/reflection originate from the broad line
region clouds. This is also supported by the resolved width of the iron narrow
Kalpha emission line, consistent with the width of the broad Hbeta line.


title:
New factorization algorithm based on a continuous representation of
  truncated Gauss sums

abstract:
  In this paper, we will describe a new factorization algorithm based on the
continuous representation of Gauss sums, generalizable to orders j>2. Such an
algorithm allows one, for the first time, to find all the factors of a number N
in a single run without precalculating the ratio N/l, where l are all the
possible trial factors. Continuous truncated exponential sums turn out to be a
powerful tool for distinguishing factors from non-factors (we also suggest,
with regard to this topic, to read an interesting paper by S. Woelk et al. also
published in this issue [Woelk, Feiler, Schleich, J. Mod. Opt. in press]) and
factorizing different numbers at the same time. We will also describe two
possible M-path optical interferometers, which can be used to experimentally
realize this algorithm: a liquid crystal grating and a generalized symmetric
Michelson interferometer.


title: Decoherence and Recoherence in Model Quantum Systems

abstract:
  We discuss the various manifestations of quantum decoherence in the forms of
dephasing, entanglement with the environment, and revelation of "which-path"
information. As a specific example, we consider an electron interference
experiment. The coupling of the coherent electrons to the quantized
electromagnetic field illustrates all of these versions of decoherence. This
decoherence has two equivalent interpretations, in terms of photon emission or
in terms of Aharonov-Bohm phase fluctuations. We consider the case when the
coherent electrons are coupled to photons in a squeezed vacuum state. The
time-averaged result is increased decoherence. However, if only electrons which
are emitted during selected periods are counted, the decoherence can be
suppressed below the level for the photon vacuum. This is the phenomenon of
recoherence. This effect is closely related to the quantum violations of the
weak energy condition, and is restricted by similar inequalities. We give some
estimates of the magnitude of the recoherence effect and discuss prospects for
observing it in an electron interferometry experiment.


title:
Casimir manipulations: The orientation dependence of fluctuation-induced
  forces

abstract:
  The Casimir interaction between two objects, or between an object and a
plane, depends on their relative orientations. We make these angular
dependences explicit by considering prolate or oblate spheroids. The variation
with orientation is calculated exactly at asymptotically large distances for
the electromagnetic field, and at arbitrary separations for a scalar field. For
a spheroid in front of a mirror, the leading term is orientation independent,
and we find the optimal orientation from computations at higher order.


title: Non-minimal universal extra dimensions

abstract:
  In this paper we investigate the phenomenological implications of boundary
localized terms (BLTs) in the model of Universal Extra Dimensions (UED). In
particular, we study the electroweak Kaluza-Klein mass spectrum resulting from
BLTs and their effect on electroweak symmetry breaking via the five dimensional
Higgs mechanism. We find that the addition of BLTs to massive five dimensional
fields induces a non-trivial extra dimensional profile for the zero and
non-zero Kaluza-Klein (KK) modes. Hence BLTs generically lead to a modification
of Standard Model parameters and are therefore experimentally constrained, even
at tree level. We study Standard Model constraints on three representative
non-minimal UED models in detail and find that the constraints on BLTs are
weak. On the contrary, non-zero BLTs have a major impact on the spectrum and
couplings of non-zero KK modes. For example, there are regions of parameter
space where the Lightest Kaluza-Klein particle (LKP) is either the Kaluza-Klein
Higgs boson or the first KK mode of the W^3.


title:
Effects of theta on the deuteron binding energy and the triple-alpha
  process

abstract:
  We study the effects that a non zero strong-CP-violating parameter theta
would have on the deuteron and diproton binding energies and on the
triple-alpha process. Both these systems exhibit fine tuning, so it is
plausible that a small change in the nuclear force would produce catastrophic
consequences. Such a nuclear force is here understood in the framework of an
effective Lagrangian for pions and nucleons, and the strength of the
interaction varies with theta. We find that the effects are not too dramatic.


title: Using curvature invariants for wave extraction in numerical relativity

abstract:
  We present a new expression for the Weyl scalar Psi_4 that can be used in
numerical relativity to extract the gravitational wave content of a spacetime.
The formula relies upon the identification of transverse tetrads, namely the
ones in which Psi_1=Psi_3=0. It is well known that tetrads with this property
always exist in a general Petrov type I spacetime. A sub-class of these tetrads
naturally converges to the Kinnersley tetrad in the limit of Petrov type D
spacetime. However, the transverse condition fixes only four of the six
parameters coming from the Lorentz group of transformations applied to tetrads.
Here we fix the tetrad completely, in particular by giving the expression for
the spin-boost transformation that was still unclear. The value of Psi_4 in
this optimal tetrad is given as a function of the two curvature invariants I
and J.


title:
The intrinsic electronic phase diagram of iron-oxypnictide
  superconductors

abstract:
  We present the first comprehensive derivation of the intrinsic electronic
phase diagram of the iron-oxypnictide superconductors in the normal state based
on the analysis of the electrical resistivity $\rho$ of both
LaFeAsO$_{1-x}$F$_x$ and SmFeAsO$_{1-x}$F$_x$ for a wide range of doping. Our
data give clear-cut evidence for unusual normal state properties in these new
materials. In particular, the emergence of superconductivity at low doping
levels is accompanied by distinct anomalous transport behavior in $\rho$ of the
normal state which is reminiscent of the spin density wave (SDW) signature in
the parent material. At higher doping levels $\rho$ of LaFeAsO$_{1-x}$F$_x$
shows a clear transition from this pseudogap-like behavior to Fermi liquid-like
behavior, mimicking the phase diagram of the cuprates. Moreover, our data
reveal a correlation between the strength of the anomalous features and the
stability of the superconducting phase. The pseudogap-like features become
stronger in SmFeAsO$_{1-x}$F$_x$ where superconductivity is enhanced and vanish
when superconductivity is reduced in the doping region with Fermi liquid-like
behavior.


title: Double Compact Objects as Low-frequency Gravitational Wave Sources

abstract:
  We study the Galactic field population of double compact objects (NS-NS,
BH-NS, BH-BH binaries) to investigate the number (if any) of these systems that
can potentially be detected with LISA at low gravitational-wave frequencies. We
calculate the Galactic numbers and physical properties of these binaries and
show their relative contribution from the disk, bulge and halo. Although the
Galaxy hosts 10^5 double compact object binaries emitting low-frequency
gravitational waves, only a handful of these objects in the disk will be
detectable with LISA, but none from the halo or bulge. This is because the bulk
of these binaries are NS-NS systems with high eccentricities and long orbital
periods (weeks/months) causing inefficient signal accumulation (small number of
signal bursts at periastron passage in 1 yr of LISA observations) rendering
them undetectable in the majority of these cases. We adopt two evolutionary
models that differ in their treatment of the common envelope phase that is a
major (and still mostly unknown) process in the formation of close double
compact objects. Depending on the adopted evolutionary model, our calculations
indicate the likely detection of about 4 NS-NS binaries and 2 BH-BH systems
(model A; likely survival of progenitors through CE) or only a couple of NS-NS
binaries (model B; suppression of the double compact object formation due to CE
mergers).


title: O(g) plasma effects in jet quenching

abstract:
  We consider the bremsstrahlung energy loss of high energy partons moving in
the quark-gluon plasma, at weak coupling. We show that the rates for these
processes receive large O(g) corrections from classical (nonabelian) plasma
physics effects, which are calculated. In the high-energy (deep LPM) regime
these corrections can be absorbed in a change of the transverse momentum
broadening coefficient $\hat{q}$, which we give to the next-to-leading order.
The correction is large even at relatively weak couplings $\alpha_s\sim 0.1$,
as is typically found for such effects, signaling difficulties with the
perturbative expansion. Our approach is based on an effective
"Euclideanization" property of classical physics near the light-cone, which
allows an effective theory approach based on dimensional reduction and suggests
a new possibility for the nonperturbative lattice study of these effects.


title: Perfectness of Kirillov-Reshetikhin crystals for nonexceptional types

abstract:
  For nonexceptional types, we prove a conjecture of Hatayama et al. about the
prefectness of Kirillov-Reshetikhin crystals.


title: Reactive Collisions of Ultracold Molecules Confined in quasi-2D Geometry

abstract:
  We present a formalism for rigorous calculations of cross sections for
inelastic and reactive collisions of ultracold atoms and molecules confined by
laser fields in quasi-2D geometry. Our results show that the
elastic-to-inelastic ratios of collision cross sections are enhanced in the
presence of a laser confinement and that the threshold energy dependence of the
collision cross sections can be tuned by varying the confinement strength and
external magnetic fields. The enhancement of the elastic-to-inelastic ratios is
inversely proportional to $\sqrt{\epsilon/\hbar \omega_0}$, where $\epsilon$ is
the kinetic energy and $\omega_0$ is the oscillation frequency of the trapped
particles in the confinement potential.


title:
Markov switching negative binomial models: an application to vehicle
  accident frequencies

abstract:
  In this paper, two-state Markov switching models are proposed to study
accident frequencies. These models assume that there are two unobserved states
of roadway safety, and that roadway entities (roadway segments) can switch
between these states over time. The states are distinct, in the sense that in
the different states accident frequencies are generated by separate counting
processes (by separate Poisson or negative binomial processes). To demonstrate
the applicability of the approach presented herein, two-state Markov switching
negative binomial models are estimated using five-year accident frequencies on
Indiana interstate highway segments. Bayesian inference methods and Markov
Chain Monte Carlo (MCMC) simulations are used for model estimation. The
estimated Markov switching models result in a superior statistical fit relative
to the standard (single-state) negative binomial model. It is found that the
more frequent state is safer and it is correlated with better weather
conditions. The less frequent state is found to be less safe and to be
correlated with adverse weather conditions.


title: On $k$-free-like groups

abstract:
  A $k$-free like group is a $k$-generated group $G$ with a sequence of
$k$-element generating sets $Z_n$ such that the girth of $G$ relative to $Z_n$
is unbounded and the Cheeger constant of $G$ relative to $Z_n$ is bounded away
from 0. By a recent result of Benjamini-Nachmias-Peres, this implies that the
critical bond percolation probability of the Cayley graph of $G$ relative to
$Z_n$ tends to $1/(2k-1)$ as $n\to \infty$. Answering a question of Benjamini,
we construct many non-free groups that are $k$-free like for all sufficiently
large $k$.


title: Spin Bias Measurement Based on a Quantum Point Contact

abstract:
  Electron charge transport through a quantum point contact (QPC) driven by an
asymmetric spin bias is studied. A large charge current is induced when the
transmission coefficient of the QPC jumps from one integer plateau to the next.
Furthermore, for an open external circuit, the induced charge bias instead of
the charge current is found to be quite large. It provides an efficient and
practical way to detect spin bias by using a very simple device, a QPC or a STM
tip. In addition, with the aid of magnetic field, polarization direction of the
spin bias can also be determined.


title:
A Priori Bounds for the Vorticity of Axis Symmetric Solutions to the
  Navier-Stokes Equations

abstract:
  We obtain a pointwise, a priori bound for the vorticity of axis symmetric
solutions to the 3 dimensional Navier-Stokes equations. The bound is in the
form of a reciprocal of a power of the distance to the axis of symmetry. This
seems to be the first general pointwise estimate established for the axis
symmetric Navier-Stokes equations.


title:
Topological insulator: a new quantized spin Hall resistance robust to
  dephasing

abstract:
  The influence of dephasing on the quantum spin Hall effect (QSHE) is studied.
In the absence of dephasing, the longitudinal resistance in a QSHE system
exhibits the quantum plateaus. We find that these quantum plateaus are robust
against the normal dephasing but fragile with the spin dephasing. Thus, these
quantum plateaus only survive in mesoscopic samples. Moreover, the longitudinal
resistance increases linearly with the sample length but is insensitive to the
sample width. These characters are in excellent agreement with the recent
experimental results [science {\bf 318}, 766 (2007)]. In addition, we define a
new spin Hall resistance that also exhibits quantum plateaus. In particular,
these plateaus are robust against any type of dephasing and therefore, survive
in macroscopic samples and better reflect the topological nature of QSHE.


title:
Coupled-Channels Approach for Dissipative Quantum Dynamics in
  Near-Barrier Collisions

abstract:
  A novel quantum dynamical model based on the dissipative quantum dynamics of
open quantum systems is presented. It allows the treatment of both
deep-inelastic processes and quantum tunneling (fusion) within a fully quantum
mechanical coupled-channels approach. Model calculations show the transition
from pure state (coherent) to mixed state (decoherent and dissipative) dynamics
during a near-barrier nuclear collision. Energy dissipation, due to
irreversible decay of giant-dipole excitations of the interacting nuclei,
results in hindrance of quantum tunneling.


title: Stability of Localized Operators

abstract:
  Let $\ell^p, 1\le p\le \infty$, be the space of all $p$-summable sequences
and $C_a$ be the convolution operator associated with a summable sequence $a$.
It is known that the $\ell^p$- stability of the convolution operator $C_a$ for
different $1\le p\le \infty$ are equivalent to each other, i.e., if $C_a$ has
$\ell^p$-stability for some $1\le p\le \infty$ then $C_a$ has
$\ell^q$-stability for all $1\le q\le \infty$. In the study of spline
approximation, wavelet analysis, time-frequency analysis, and sampling, there
are many localized operators of non-convolution type whose stability is one of
the basic assumptions. In this paper, we consider the stability of those
localized operators including infinite matrices in the Sj\"ostrand class,
synthesis operators with generating functions enveloped by shifts of a function
in the Wiener amalgam space, and integral operators with kernels having certain
regularity and decay at infinity. We show that the $\ell^p$- stability (or
$L^p$-stability) of those three classes of localized operators are equivalent
to each other, and we also prove that the left inverse of those localized
operators are well localized.


title:
Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe
  (Fe1+dSe)

abstract:
  The recently discovered iron arsenide superconductors, which display
superconducting transition temperatures as high as 55 K, appear to share a
number of general features with high-Tc cuprates, including proximity to a
magnetically ordered state and robustness of the superconductivity in the
presence of disorder. Here we show that superconductivity in Fe1+dSe, the
parent compound of the superconducting arsenide family, is destroyed by very
small changes in stoichiometry. Further, we show that non-superconducting
Fe1+dSe is not magnetically ordered down to low temperatures. These results
suggest that robust superconductivity and immediate instability against an
ordered magnetic state should not be considered as intrinsic characteristics of
iron-based superconducting systems, and that Fe1+dSe may present a unique
opportunity for determining which materials characteristics are critical to the
existence of superconductivity in high Tc iron arsenide superconductors and
which are not.


title: Dark Energy, Inflation and Extra Dimensions

abstract:
  We consider how accelerated expansion, whether due to inflation or dark
energy, imposes strong constraints on fundamental theories obtained by
compactification from higher dimensions. For theories that obey the null energy
condition (NEC), we find that inflationary cosmology is impossible for a wide
range of compactifications; and a dark energy phase consistent with
observations is only possible if both Newton's gravitational constant and the
dark energy equation-of-state vary with time. If the theory violates the NEC,
inflation and dark energy are only possible if the NEC-violating elements are
inhomogeneously distributed in thecompact dimensions and vary with time in
precise synchrony with the matter and energy density in the non-compact
dimensions. Although our proofs are derived assuming general relativity applies
in both four and higher dimensions and certain forms of metrics, we argue that
similar constraints must apply for more general compactifications.


title: Casimir interaction among heavy fermions in the BCS-BEC crossover

abstract:
  We investigate a two-species Fermi gas with a large mass ratio interacting by
an interspecies short-range interaction. Using the Born-Oppenheimer
approximation, we determine the interaction energy of two heavy fermions
immersed in the Fermi sea of light fermions as a function of the s-wave
scattering length. In the BCS limit, we recover the perturbative calculation of
the effective interaction between heavy fermions. The p-wave projection of the
effective interaction is attractive in the BCS limit while it turns out to be
repulsive near the unitarity limit. We find that the p-wave attraction reaches
its maximum between the BCS and unitarity limits, where the maximal p-wave
pairing of heavy minority fermions is expected. We also investigate the case
where the heavy fermions are confined in two dimensions and the p-wave
attraction between them is found to be stronger than that in three dimensions.