title:
Posterior Convergence and Model Estimation in Bayesian Change-point
  Problems

abstract:
  We study the posterior distribution of the Bayesian multiple change-point
regression problem when the number and the locations of the change-points are
unknown. While it is relatively easy to apply the general theory to obtain the
$O(1/\sqrt{n})$ rate up to some logarithmic factor, showing the exact
parametric rate of convergence of the posterior distribution requires
additional work and assumptions. Additionally, we demonstrate the asymptotic
normality of the segment levels under these assumptions. For inferences on the
number of change-points, we show that the Bayesian approach can produce a
consistent posterior estimate. Finally, we argue that the point-wise posterior
convergence property as demonstrated might have bad finite sample performance
in that consistent posterior for model selection necessarily implies the
maximal squared risk will be asymptotically larger than the optimal
$O(1/\sqrt{n})$ rate. This is the Bayesian version of the same phenomenon that
has been noted and studied by other authors.


title:
Getting Information on Independently Prepared Quantum States -- When Are
  Individual Measurements as Powerful as Joint Measurements?

abstract:
  Given a composite quantum system in which the states of the subsystems are
independently (but not necessarily identically) prepared, we construct separate
measurements on the subsystems from any given joint measurement such that the
former always give at least as large information as the latter. This
construction offers new insights into the understanding of measurements on this
type of composite systems. Moreover, this construction essentially proves the
intuition that separate measurements on the subsystems are sufficient to
extract the maximal information about the separately prepared subsystems, thus
making a joint measurement unnecessary. Furthermore, our result implies that
individual attacks are as powerful as collective attacks in obtaining
information on the raw key in quantum key distribution.


title: $J/\psi$ suppression and $p_T$ spectra in RHIC and LHC energy collisions

abstract:
  In a hydrodynamic model, we have studied $J/\psi$ production in Au+Au/Cu+Cu
collisions at RHIC energy $\sqrt{s}$=200 GeV. At the initial time, $J/\psi$'s
are randomly distributed in the fluid. As the fluid evolve in time, the free
streaming $J/\psi$'s are dissolved if the local fluid temperature exceeds a
threshold temperature $T_{J/\psi}$. Sequential melting of charmonium states
($\chi_c$, $\psi\prime$ and $J/\psi$), with melting temperatures
$T_{\chi_c}=T_{\psi\prime} \approx 1.2T_c$, $T_{J/\psi} \approx2T_c$ and
feed-down fraction $F\approx 0.3$, explains the PHENIX data on the centrality
dependence of $J/\psi$ suppression in Au+Au collisions. $J/\psi$ $p_T$ spectra
and the nuclear modification factor in Au+Au collisions are also well explained
in the model. The model however over predict centrality dependence of $J/\psi$
suppression in Cu+Cu collisions by 20-30%. The $J/\psi$ $p_T$ spectra are under
predicted by 20-30%. The model predict that in central Pb+Pb collisions at LHC
energy, $\sqrt{s}$=5500 GeV, $J/\psi$'s are suppressed by a factor of $\sim$
10. The model predicted $J/\psi$ $p_T$ distribution in Pb+Pb collisions at LHC
is similar to that in Au+Au collisions at RHIC.


title:
Low-Signal-Energy Asymptotics of Capacity and Mutual Information for the
  Discrete-Time Poisson Channel

abstract:
  The first terms of the low-signal-energy asymptotics for the mutual
information in the discrete-time Poisson channel are derived and compared to an
asymptotic expression of the capacity. In the presence of non-zero additive
noise (either Poisson or geometric), the mutual information is concave at zero
signal-energy and the minimum energy per bit is not attained at zero capacity.
Fixed signal constellations which scale with the signal energy do not attain
the minimum energy per bit. The minimum energy per bit is zero when additive
Poisson noise is present and $\ew\log 2$ when additive geometric noise of mean
$\ew$ is present.


title:
Bound states and scattering lengths of three two-component particles
  with zero-range interactions under one-dimensional confinement

abstract:
  The universal three-body dynamics in ultra-cold binary gases confined to
one-dimensional motion are studied. The three-body binding energies and the (2
+ 1)-scattering lengths are calculated for two identical particles of mass $m$
and a different one of mass $m_1$, which interactions is described in the
low-energy limit by zero-range potentials. The critical values of the mass
ratio $m/m_1$, at which the three-body states arise and the (2 + 1)-scattering
length equals zero, are determined both for zero and infinite interaction
strength $\lambda_1$ of the identical particles. A number of exact results are
enlisted and asymptotic dependences both for $m/m_1 \to \infty$ and $\lambda_1
\to -\infty$ are derived. Combining the numerical and analytical results, a
schematic diagram showing the number of the three-body bound states and the
sign of the (2 + 1)-scattering length in the plane of the mass ratio and
interaction-strength ratio is deduced. The results provide a description of the
homogeneous and mixed phases of atoms and molecules in dilute binary quantum
gases.


title:
Formal topology and constructive mathematics: the Gelfand and
  Stone-Yosida representation theorems

abstract:
  We present a constructive proof of the Stone-Yosida representation theorem
for Riesz spaces motivated by considerations from formal topology. This theorem
is used to derive a representation theorem for f-algebras. In turn, this
theorem implies the Gelfand representation theorem for C*-algebras of operators
on Hilbert spaces as formulated by Bishop and Bridges. Our proof is shorter,
clearer, and we avoid the use of approximate eigenvalues.


title: Re-analysis of data on a0(1450) and a0(980)

abstract:
  Four sets of data determining parameters of a0(1450) and a0(980) are
re-analysed. These are Crystal Barrel data for pbar-p annihilation at rest to
eta-pizero-pizero in (i) liquid hydrogen and (ii) gas, and to (iii)
K0_L-picharged-Kcharged and (iv) omega piplus-piminus-pizero (mostly
omega-rho-pi). Dispersive corrections due to opening of inelastic thresholds
are treated fully. This stabilises parameters of a0(1450) substantially. The
mass of its peak is 1448 +-13(stat) +- 25(syst) MeV and its mean full width at
half maximum is 192 +-9 +-9 MeV. The pole position is 1432 +- 13 +- 25 - i(98
+-5 +-5) MeV. At the peak, eta-pi, omega-rho and a0(980)-sigma decay
intensities are in the ratios 1 : 9.2 +- 0.8 +- 1.3 : 3.1 +- 0.2 +- 0.9. There
is no evidence for a separate a0 near 1300 MeV claimed by Obelix. Parameters of
a0(980) are updated to M = 987.4 +- 1.0 +- 3.0 MeV, g^2(eta-pi) = 0.164 +-
0.007 +- 0.010 GeV^2, g^2(KK)/g^2(eta-pi) = 1.05 +- 0.07 +- 0.05. The nature of
the prominent J^{PC} = 0^{-+} signal in omega-rho is also clarified.


title: A Note on Symmetries of WDVV Equations

abstract:
  We investigate symmetries of Witten-Dijkgraaf-E.Verlinde-H.Verlinde (WDVV)
equations proposed by Dubrovin from bi-hamiltonian point of view. These
symmetries can be viewed as canonical Miura transformations between genus-zero
bi-hamiltonian systems of hydrodynamic type. In particular,we show that the
moduli space of two-primary models under symmetries of WDVV can be
characterized by the polytropic exponent $h$. Furthermore, we also discuss the
transformation properties of free energy at genus-one level.


title: Gauge fields in accelerated frames

abstract:
  Quantized fields in accelerated frames (Rindler spaces) with emphasis on
gauge fields are investigated. Important properties of the dynamics in Rindler
spaces are shown to follow from the scale invariance of the corresponding
Hamiltonians. Origin and consequences of this extraordinary property of
Hamiltonians in Rindler spaces are elucidated. Characteristics of the Unruh
radiation, the appearance of a photon condensate and the interaction energy of
vector and scalar static charges are discussed and implications for Yang-Mills
theories and QCD in Rindler spaces are indicated.


title:
Invariant manifolds for analytic dynamical systems over ultrametric
  fields

abstract:
  We give an exposition of the theory of invariant manifolds around a fixed
point, in the case of time-discrete, analytic dynamical systems over a complete
ultrametric field K.
  Typically, we consider an analytic manifold M modelled on an ultrametric
Banach space over K, an analytic self-map f of M, and a fixed point p of f.
Under suitable conditions on the tangent map of f at p, we construct a
centre-stable manifold, a centre manifold, respectively, an r-stable manifold
around p, for a given positive real number r not exceeding 1.
  The invariant manifolds are useful in the theory of Lie groups over local
fields, where they allow results to be extended to the case of positive
characteristic which previously were only available in characteristic zero
(i.e., for p-adic Lie groups).


title:
Local Convergence and Global Diversity: From Interpersonal to Social
  Influence

abstract:
  Axelrod (1997) showed how local convergence in cultural influence can
preserve cultural diversity. We argue that central implications of Axelrod's
model may change profoundly, if his model is integrated with the assumption of
social influence as assumed by an earlier generation of modelers. Axelrod and
all follow up studies employed instead the assumption that influence is
interpersonal (dyadic). We show how the combination of social influence with
homophily allows solving two important problems. Our integration of social
influence yields monoculture in small societies and diversity increasing in
population size, consistently with empirical evidence but contrary to earlier
models. The second problem was identified by Klemm et al.(2003a,b), an
extremely narrow window of noise levels in which diversity with local
convergence can be obtained at all. Our model with social influence generates
stable diversity with local convergence across a much broader interval of noise
levels than models based on interpersonal influence.


title:
A search for rapid pulsations in the magnetic cool chemically peculiar
  star HD3980

abstract:
  The Ap star HD3980 appears to be a promising roAp candidate based on its
fundamental parameters, leading us to search for rapid pulsations with the VLT
UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and
estimated temperature of 8100K place HD3980 in the middle of the theoretical
instability strip for rapidly oscillating Ap stars, about halfway through its
main sequence evolution stage. The star has a strong, variable magnetic field,
as is typical of the cool magnetic Ap stars. Dipole model parameters were
determined from VLT observations using FORS1. From Doppler shift measurements
for individual spectral lines of rare earth elements and the H-alpha line core,
we find no pulsations above 20-30 m/s. This result is corroborated by
inspection of lines of several other chemical elements, as well as with
crosscorrelation for long spectral regions with the average spectrum as a
template. Abundances of chemical elements were determined and show larger than
solar abundances of rare earth elements. Further, ionisation disequilibria for
the first two ionised states of Nd and Pr are detected. We also find that the
star has a strong overabundance of manganese, which is typical for much hotter
HgMn and other Bp stars. Line profile variability with the rotation period was
detected for the majority of chemical species.


title: Magnetic support of the optical emission line filaments in NGC 1275

abstract:
  The giant elliptical galaxy NGC 1275, at the centre of the Perseus cluster,
is surrounded by a well-known giant nebulosity of emission-line filaments,
which are plausibly about >10^8 yr old. The filaments are dragged out from the
centre of the galaxy by the radio bubbles rising buoyantly in the hot
intracluster gas before later falling back. They act as dramatic markers of the
feedback process by which energy is transferred from the central massive black
hole to the surrounding gas. The mechanism by which the filaments are
stabilized against tidal shear and dissipation into the surrounding 4x10^7 K
gas has been unclear. Here we report new observations that resolve thread-like
structures in the filaments. Some threads extend over 6 kpc, yet are only 70 pc
wide. We conclude that magnetic fields in the threads, in pressure balance with
the surrounding gas, stabilize the filaments, so allowing a large mass of cold
gas to accumulate and delay star formation.


title: Recognizing trace graphs of closed braids

abstract:
  To a closed braid in a solid torus we associate a trace graph in a thickened
torus in such a way that closed braids are isotopic if and only if their trace
graphs can be related by trihedral and tetraherdal moves. For closed braids
with a fixed number of strands, we recognize trace graphs up to isotopy and
trihedral moves in polynomial time with respect to the braid length.


title: Chiral Symmetry breaking in Three Dimensional QED

abstract:
  Over the past few years three dimensional Quantum Electrodynamics (QED$_3$)
has attracted a lot of attention, because it may be an effective theory for the
underdoped and non-superconducting region of the phase diagram of high $T_c$
cuprate compounds. We present results from lattice simulations of the
non-compact version of the theory in order to address the issue of whether
chiral symmetry is spontaneously broken when the number of fermion flavours
$N_f$ is less than a critical value $N_{fc}$. Our results provide strong
evidence that QED$_3$ is chirally symmetric for $N_f \geq 1.5$, implying that a
pseudogap phase separates the superconducting phase from the antiferromagnetic
phase.


title: Thermodynamics of the Spin Luttinger-Liquid in a Model Ladder Material

abstract:
  The phase diagram in temperature and magnetic field of the metal-organic,
two-leg, spin-ladder compound (C5H12N)2CuBr4 is studied by measurements of the
specific heat and the magnetocaloric effect. We demonstrate the presence of an
extended spin Luttinger-liquid phase between two field-induced quantum critical
points and over a broad range of temperature. Based on an ideal spin-ladder
Hamiltonian, comprehensive numerical modelling of the ladder specific heat
yields excellent quantitative agreement with the experimental data across the
complete phase diagram.


title: Cusp areas of Farey manifolds and applications to knot theory

abstract:
  This paper gives the first explicit, two-sided estimates on the cusp area of
once-punctured torus bundles, 4-punctured sphere bundles, and 2-bridge link
complements. The input for these estimates is purely combinatorial data coming
from the Farey tesselation of the hyperbolic plane. The bounds on cusp area
lead to explicit bounds on the volume of Dehn fillings of these manifolds, for
example sharp bounds on volumes of hyperbolic closed 3-braids in terms of the
Schreier normal form of the associated braid word. Finally, these results are
applied to derive relations between the Jones polynomial and the volume of
hyperbolic knots, and to disprove a related conjecture.


title: A note on the quantum-mechanical Ricci flow

abstract:
  We obtain Schroedinger quantum mechanics from Perelman's functional and from
the Ricci flow equations of a conformally flat Riemannian metric on a closed
2-dimensional configuration space. We explore links with the recently discussed
"emergent quantum mechanics".


title: Effects of Supernova Feedback on the Formation of Galaxies

abstract:
  We study the effects of Supernova (SN) feedback on the formation of galaxies
using hydrodynamical simulations in a Lambda-CDM cosmology. We use an extended
version of the code GADGET-2 which includes chemical enrichment and energy
feedback by Type II and Type Ia SN, metal-dependent cooling and a multiphase
model for the gas component. We focus on the effects of SN feedback on the star
formation process, galaxy morphology, evolution of the specific angular
momentum and chemical properties. We find that SN feedback plays a fundamental
role in galaxy evolution, producing a self-regulated cycle for star formation,
preventing the early consumption of gas and allowing disks to form at late
times. The SN feedback model is able to reproduce the expected dependence on
virial mass, with less massive systems being more strongly affected.


title: Junctions of anyonic Luttinger wires

abstract:
  We present an extended study of anyonic Luttinger liquids wires jointing at a
single point. The model on the full line is solved with bosonization and the
junction of an arbitrary number of wires is treated imposing boundary
conditions that preserve exact solvability in the bosonic language. This allows
to reach, in the low momentum regime, some of the critical fixed points found
with the electronic boundary conditions. The stability of all the fixed points
is discussed.


title: Quantum Phase Transition in a Graphene Model

abstract:
  We present results for the equation of state of a graphene-like model in an
effort to understand the properties of its quantum phase transition. The N_f
fermion species interact through a three dimensional instantaneous Coulomb
potential. Since there are no reliable analytical tools that work for all
values of N_f and the coupling constant g, we rely on Monte Carlo simulations
to calculate the critical properties of the model near the phase transition. We
consider the four-component formulation for the fermion fields, which arises
naturally as the continuum limit of the staggered fermion construction in (2+1)
dimensions. In the limit of infinitely strong Coulomb interaction, the system
undergoes a quantum phase transition at a critical number of fermion species
N_fc ~ 4.7. We also calculate the values of the critical exponents at the
quantum phase transition.


title:
Nonequilibrium critical relaxations of the order parameter and energy in
  the two-dimensional ferromagnetic Potts model

abstract:
  The static and dynamic critical properties of the ferromagnetic q-state Potts
models on a square lattice with q = 2 and 3 are numerically studied via the
nonequilibrium relaxation method. The relaxation behavior of both the order
parameter and energy as well as that of the second moments are investigated,
from which static and dynamic critical exponents can be obtained. We find that
the static exponents thus obtained from the relaxation of the order parameter
and energy together with the second moments of the order parameter exhibit a
close agreement with the exact exponents, especially for the case of q = 2
(Ising) model, when care is taken in the choice of the initial states for the
relaxation of the second moments. As for the case of q = 3, the estimates for
the static exponents become less accurate but still exhibit reasonable
agreement with the exactly known static exponents. The dynamic critical
exponent for q = 2 (Ising) model is estimated from the relaxation of the second
moments of the order parameter with mixed initial conditions to give z(q = 2) =
2.1668(19).


title:
Modelling the evolution and nucleosynthesis of carbon-enhanced
  metal-poor stars

abstract:
  We present the results of binary population simulations of carbon-enhanced
metal-poor (CEMP) stars. We show that nitrogen and fluorine are useful tracers
of the origin of CEMP stars, and conclude that the observed paucity of very
nitrogen-rich stars puts strong constraints on possible modifications of the
initial mass function at low metallicity. The large number fraction of CEMP
stars may instead require much more efficient dredge-up from low-metallicity
asymptotic giant branch stars.


title: Smoothing noisy spectroscopic data with many-knot spline method

abstract:
  In this paper, we present the development of a many-knot spline method
derived to remove the statistical noise in the spectroscopic data. This method
is an expansion of the B-spline method. Compared to the B-spline method, the
many-knot spline method is significantly faster.


title: Bosons in Rapid Rotation

abstract:
  Some recent progress in the mathematical physics of rapidly rotating, dilute
Bose gases in anharmonic traps is reviewed.


title:
Perturbation method for determining the group of invariance of
  hierarchical models

abstract:
  We propose a perturbation method for determining the (largest) group of
invariance of a toric ideal defined in Aoki and Takemura [2008a]. In the
perturbation method, we investigate how a generic element in the row space of
the configuration defining a toric ideal is mapped by a permutation of the
indeterminates. Compared to the proof in Aoki and Takemura [2008a] which was
based on stabilizers of a subset of indeterminates, the perturbation method
gives a much simpler proof of the group of invariance. In particular, we
determine the group of invariance for a general hierarchical model of
contingency tables in statistics, under the assumption that the numbers of the
levels of the factors are generic. We prove that it is a wreath product indexed
by a poset related to the intersection poset of the maximal interaction effects
of the model.


title:
Relaxation dynamics and interrupted coarsening in irrationally
  frustrated superconducting arrays

abstract:
  Equilibrium and non-equilibrium relaxation behaviors of two-dimensional
superconducting arrays are investigated via numerical simulations at low
temperatures in the presence of incommensurate transverse magnetic fields, with
frustration parameter f= (3-\sqrt{5})/2. We find that the non-equilibrium
relaxation, beginning with random initial states quenched to low temperatures,
exhibits a three-stage relaxation of chirality autocorrelations. At the early
stage, the relaxation is found to be described by the von Schweidler form. Then
it exhibits power-law behavior in the intermediate time scale and faster decay
in the long-time limit, which together can be fitted to the Ogielski form; for
longer waiting times, this crosses over to a stretched exponential form. We
argue that the power-law behavior in the intermediate time scale may be
understood as a consequence of the coarsening behavior, leading to the local
vortex order corresponding to f=2/5 ground-state configurations. High mobility
of the vortices in the domain boundaries, generating slow wandering motion of
the domain walls, may provide mechanism of dynamic heterogeneity and account
for the long-time stretched exponential relaxation behavior. It is expected
that such meandering fluctuations of the low-temperature structure give rise to
finite resistivity at those low temperatures; this appears consistent with the
zero-temperature resistive transition in the limit of irrational frustration.


title: Passive Sliders and Scaling: from Cusps to Divergences

abstract:
  The steady state reached by a system of particles sliding down a fluctuating
surface has interesting properties. Particle clusters form and break rapidly,
leading to a broad distribution of sizes and large fluctuations. The
density-density correlation function is a singular scaling function of the
separation and system size. A simple mapping is shown to take a configuration
of sliding hard-core particles with mutual exclusion (a system which shows a
cusp singularity) to a configuration with multiparticle occupancy. For the
mapped system, a calculation of the correlation function shows that it is of
the same scaling form again, but with a stronger singularity (a divergence) of
the sort observed earlier for noninteracting passive particles.


title: Charged rotating black holes in six-dimensional gauged supergravity

abstract:
  We obtain non-extremal charged rotating black holes in six-dimensional SU(2)
gauged supergravity with two independent angular momenta and one U(1) charge.
These include supersymmetric black holes without naked closed timelike curves.


title: Multiplicity one theorem for (GL(n+1,R),GL(n,R))

abstract:
  Let F be either R or C. Consider the standard embedding GL(n,F)<GL(n+1,F) and
the action of GL(n,F) on GL(n+1,F) by conjugation.
  In this paper we show that any GL(n,F)-invariant distribution on GL(n+1,F) is
invariant with respect to transposition.
  We show that this implies that for any irreducible admissible smooth Frechet
representations $\pi$ of GL(n+1,F) and $\tau$ of GL(n,F),
  $$dim Hom_{GL(n,F)}(\pi,\tau) \leq 1.$$
  For p-adic fields those results were proven in [AGRS].


title:
On the Advancements of Conformal Transformations and their Associated
  Symmetries in Geometry and Theoretical Physics

abstract:
  The historical developments of conformal transformations and symmetries are
sketched: Their origin from stereographic projections of the globe, their
blossoming in two dimensions within the field of analytic complex functions,
the generic role of transformations by reciprocal radii in dimensions higher
than two and their linearization in terms of polyspherical coordinates by
Darboux, Weyl's attempt to extend General Relativity, the slow rise of finite
dimensional conformal transformations in classical field theories and the
problem of their interpretation, then since about 1970 the rapid spread of
their acceptance for asymptotic and structural problems in quantum field
theories and beyond, up to the current AdS/CFT conjecture. The occasion for the
present article: hundred years ago Bateman and Cunningham discovered the form
invariance of Maxwell's equations for electromagnetism with respect to
conformal space-time transformations.

categories: physics.hist-ph gr-qc hep-th math-ph math.MP


title:
Efficient rare-event simulation for the maximum of heavy-tailed random
  walks

abstract:
  Let $(X_n:n\geq 0)$ be a sequence of i.i.d. r.v.'s with negative mean. Set
$S_0=0$ and define $S_n=X_1+... +X_n$. We propose an importance sampling
algorithm to estimate the tail of $M=\max \{S_n:n\geq 0\}$ that is strongly
efficient for both light and heavy-tailed increment distributions. Moreover, in
the case of heavy-tailed increments and under additional technical assumptions,
our estimator can be shown to have asymptotically vanishing relative variance
in the sense that its coefficient of variation vanishes as the tail parameter
increases. A key feature of our algorithm is that it is state-dependent. In the
presence of light tails, our procedure leads to Siegmund's (1979) algorithm.
The rigorous analysis of efficiency requires new Lyapunov-type inequalities
that can be useful in the study of more general importance sampling algorithms.


title: Collective generation of quantum states of light by entangled atoms

abstract:
  We present a theoretical framework to describe the collective emission of
light by entangled atomic states. Our theory applies to the low excitation
regime, where most of the atoms are initially in the ground state, and relies
on a bosonic description of the atomic excitations. In this way, the problem of
light emission by an ensemble of atoms can be solved exactly, including
dipole-dipole interactions and multiple light scattering. Explicit expressions
for the emitted photonic states are obtained in several situations, such as
those of atoms in regular lattices and atomic vapors. We determine the
directionality of the photonic beam, the purity of the photonic state, and the
renormalization of the emission rates. We also show how to observe collective
phenomena with ultracold atoms in optical lattices, and how to use these ideas
to generate photonic states that are useful in the context of quantum
information.


title: Long term radio variability of AGN

abstract:
  A large number of AGN have been monitored for nearly 30 years at 22, 37 and
87 GHz in Mets\"ahovi Radio Observatory. These data were combined with lower
frequency 4.8, 8.0 and 14.5 GHz data from the University of Michigan Radio
Astronomy Observatory, higher frequency data at 90 and 230 GHz from SEST, and
supplementary higher frequency data from the literature to study the long-term
variability of a large sample of AGN. Both the characteristics of individual
flares from visual inspection and statistically-determined variability
timescales as a function of frequency and optical class type were determined.
Based on past behaviour, predictions of sources expected to exhibit large
flares in 2008--2009 appropriate for study by GLAST and other instruments are
made. The need for long-term data for properly understanding source behaviour
is emphasised.


title:
Elasticity of Spider dragline Silks Viewed as Nematics: Yielding Induced
  by Isotropic-Nematic Phase Transition

abstract:
  Spider dragline silk shows well-known outstanding mechanical properties.
However, its sigmoidal shape of the measured stress-strain curves (i.e. the
yield) can not be described by classical polymer theories and recent
hierarchical chain model. To solve the long lasting problem, we generalized the
Maier-Saupe theory of nematics to construct an elastic model for the
polypeptide chain network of the dragline silk. The comprehensive agreement
between theory and experiments on the stress-strain curve strongly indicates
the dragline silks to belong to liquid crystal elastomers. Especially, the
remarkable yielding elasticity of the silk is understood for the first time as
the force-induced isotropic-nematic phase transition of the chain network. Our
theory also predicts a drop of the stress in supercontracted dragline silk, an
early found effect of humidity on the mechanical property in many silks.


title: Two orbits: When is one in the closure of the other?

abstract:
  Let $G$ be a connected linear algebraic group, let $V$ be a finite
dimensional algebraic $G$-module, and let $\mathcal O_1$, $\mathcal O_2$ be two
$G$-orbits in $V$. We describe a constructive way to find out whether $\mathcal
O_1$ lies in the closure of $\mathcal O_2$ or not.


title: Non-Universality of the Specific Heat in Glass Forming Systems

abstract:
  We present new simulation results for the specific heat in a classical model
of a binary mixture glass-former in two dimensions. We show that in addition to
the formerly observed specific heat peak there is a second peak at lower
temperatures which was not observable in earlier simulations. This is a
surprise, as most texts on the glass transition expect a single specific heat
peak. We explain the physics of the two specific heat peaks by the
micro-melting of two types of clusters. While this physics is easily
accessible, the consequences are that one should not expect any universality in
the temperature dependence of the specific heat in glass formers.


title: On free fermions and plane partitions

abstract:
  We use free fermion methods to re-derive a result of Okounkov and Reshetikhin
relating charged fermions to random plane partitions, and to extend it to
relate neutral fermions to strict plane partitions.


title:
Correlation effects of exchange splitting and coexistence of
  spin-density-wave and superconductivity in single crystalline Sr1-xKxFe2As2

abstract:
  The nature of spin-density wave and its relation with superconductivity are
crucial issues in the newly discovered Fe-based high temperature
superconductors. Particularly it is unclear whether the superconducting phase
and spin density wave (SDW) are truly exclusive from each other as suggested by
certain experiments. With angle resolved photoemission spectroscopy, we here
report exchange splittings of the band structures in Sr1-xKxFe2As2
(x=0,0.1,0.2), and the non-rigid-band behaviors of the splitting. Our data on
single crystalline superconducting samples unambiguously prove that SDW and
superconductivity could coexist in iron-pnictides.


title:
Temperature and frequency dependent optical properties of ultra-thin Au
  films

abstract:
  While the optical properties of thin metal films are well understood in the
visible and near-infrared range, little has been done in the mid- and
far-infrared region. Here we investigate ultra-thin gold films prepared on
Si(111)(7 x 7) in UHV by measuring in the frequency range between 500 cm-1 and
7000 cm-1 and for temperatures between 300 K and 5 K. The nominal thickness of
the gold layers ranges between one monolayer and 9 nm. The frequency and
temperature dependences of the thicker films can be well described by the Drude
model of a metal, when taking into account classical size effects due to
surface scattering. The films below the percolation threshold exhibit a
non-metallic behavior: the reflection increases with frequency and decreases
with temperature. The frequency dependence can partly be described by a
generalized Drude model. The temperature dependence does not follow a simple
activation process. For monolayers we observe a transition between surface
states around 1100 cm-1.


title: A Kind of Compact Quantum Semigroups

abstract:
  We show that the quantum family of all maps from a finite space to a finite
dimensional compact quantum semigroup has a canonical quantum semigroup
structure.


title: Entanglement, combinatorics and finite-size effects in spin-chains

abstract:
  We carry out a systematic study of the exact block entanglement in XXZ
spin-chain at Delta=-1/2. We present, the first analytic expressions for
reduced density matrices of n spins in a chain of length L (for n<=6 and
arbitrary but odd L) of a truly interacting model. The entanglement entropy,
the moments of the reduced density matrix, and its spectrum are then easily
derived. We explicitely construct the "entanglement Hamiltonian" as the
logarithm of this matrix. Exploiting the degeneracy of the ground-state, we
find the scaling behavior of entanglement of the zero-temperature mixed state.

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


title: J1420--0545: The radio galaxy larger than 3C236

abstract:
  We report the discovery of the largest giant radio galaxy, J1420-0545: a FR
type II radio source with an angular size of 17.4' identified with an optical
galaxy at z=0.3067. Thus, the projected linear size of the radio structure is
4.69 Mpc (if we assume that H_{0}=71 km\s\Mpc, Omega_{m}=0.27, and
Omega_{\Lambda}=0.73). This makes it larger than 3C236, which is the largest
double radio source known to date. New radio observations with the 100 m
Effelsberg telescope and the Giant Metrewave Radio Telescope, as well as
optical identification with a host galaxy and its optical spectroscopy with the
William Herschel Telescope are reported. The spectrum of J1420-0545 is typical
of elliptical galaxies in which continuum emission with the characteristic
4000A discontinuity and the H and K absorption lines are dominated by evolved
stars. The dynamical age of the source, its jets' power, the energy density,
and the equipartition magnetic field are calculated and compared with the
corresponding parameters of other giant and normal-sized radio galaxies from a
comparison sample. The source is characterized by the exceptionally low density
of the surrounding IGM and an unexpectedly high expansion speed of the source
along the jet axis. All of these may suggest a large inhomogeneity of the IGM.


title:
The ground-state magnetic ordering of the spin-1/2 frustrated J1-J2 XXZ
  model on the square lattice

abstract:
  Using the coupled-cluster method for infinite lattices and the exact
diagonalization method for finite lattices, we study the influence of an
exchange anisotropy Delta on the ground-state phase diagram of the spin-1/2
frustrated J1-J2 XXZ antiferromagnet on the square lattice. We find that
increasing Delta>1 (i.e. an Ising type easy-axis anisotropy) as well as
decreasing Delta<1 (i.e. an XY type easy-plane anisotropy) both lead to a
monotonic shrinking of the parameter region of the magnetically disordered
quantum phase. Finally, at Delta~1.9 this quantum phase disappears, whereas in
pure XY limit (Delta=0) there is still a narrow region around J2 =0.5J1 where
the quantum paramagnetic ground-state phase exists.


title: Ionization front-driven turbulence in the clumpy interstellar medium

abstract:
  We present 3D radiation-gasdynamical simulations of an ionization front
running into a dense clump. In our setup, a B0 star irradiates an overdensity
which is at a distance of 10 pc and modelled as a supercritical 100 M_sol
Bonnor-Ebert sphere. The radiation from the star heats up the gas and creates a
shock front that expands into the interstellar medium. The shock compresses the
clump material while the ionizing radiation heats it up. The outcome of this
"cloud-crushing" process is a fully turbulent gas in the wake of the clump. In
the end, the clump entirely dissolves. We propose that this mechanism is very
efficient in creating short-living supersonic turbulence in the vicinity of
massive stars.


title: Static and Impulsive Models of Solar Active Regions

abstract:
  The physical modeling of active regions (ARs) and of the global coronal is
receiving increasing interest lately. Recent attempts to model ARs using static
equilibrium models were quite successful in reproducing AR images of hot soft
X-ray (SXR) loops. They however failed to predict the bright EUV warm loops
permeating ARs: the synthetic images were dominated by intense footpoint
emission. We demonstrate that this failure is due to the very weak dependence
of loop temperature on loop length which cannot simultaneously account for both
hot and warm loops in the same AR. We then consider time-dependent AR models
based on nanoflare heating. We demonstrate that such models can simultaneously
reproduce EUV and SXR loops in ARs. Moreover, they predict radial intensity
variations consistent with the localized core and extended emissions in SXR and
EUV AR observations respectively. We finally show how the AR morphology can be
used as a gauge of the properties (duration, energy, spatial dependence,
repetition time) of the impulsive heating.


title: Relation Between Stellar Mass and Star Formation Activity in Galaxies

abstract:
  For a mass-selected sample of 66544 galaxies with photometric redshifts from
the Cosmic Evolution Survey (COSMOS), we examine the evolution of star
formation activity as a function of stellar mass in galaxies. We estimate the
cosmic star formation rates (SFR) over the range 0.2 < z < 1.2, using the
rest-frame 2800 A flux (corrected for extinction). We find the mean SFR to be a
strong function of the galactic stellar mass at any given redshift, with
massive systems (log (M/M(Sun)) > 10.5) contributing less (by a factor of ~ 5)
to the total star formation rate density (SFRD).
  Combining data from the COSMOS and Gemini Deep Deep Survey (GDDS), we extend
the SFRD-z relation as a function of stellar mass to z~2. For massive galaxies,
we find a steep increase in the SFRD-z relation to z~2; for the less massive
systems, the SFRD which also increases from z=0 to 1, levels off at z~1. This
implies that the massive systems have had their major star formation activity
at earlier epochs (z > 2) than the lower mass galaxies.
  We study changes in the SFRDs as a function of both redshift and stellar mass
for galaxies of different spectral types. We find that the slope of the SFRD-z
relation for different spectral type of galaxies is a strong function of their
stellar mass. For low and intermediate mass systems, the main contribution to
the cosmic SFRD comes from the star-forming galaxies while, for more massive
systems, the evolved galaxies are the most dominant population.


title: Unifying Practical Uncertainty Representations: I. Generalized P-Boxes

abstract:
  There exist several simple representations of uncertainty that are easier to
handle than more general ones. Among them are random sets, possibility
distributions, probability intervals, and more recently Ferson's p-boxes and
Neumaier's clouds. Both for theoretical and practical considerations, it is
very useful to know whether one representation is equivalent to or can be
approximated by other ones. In this paper, we define a generalized form of
usual p-boxes. These generalized p-boxes have interesting connections with
other previously known representations. In particular, we show that they are
equivalent to pairs of possibility distributions, and that they are special
kinds of random sets. They are also the missing link between p-boxes and
clouds, which are the topic of the second part of this study.


title: An iterative method for numerical integration of rational functions

abstract:
  The rational Landen transformations are used to produce a highly efficient
numerical method for the integration of rational functions.


title: An invitation to toric degenerations

abstract:
  This is an expository paper which explores the ideas of the authors' paper
"From Affine Geometry to Complex Geometry", arXiv:0709.2290. We explain the
basic ideas of the latter paper by going through a large number of concrete,
increasingly complicated examples.


title: A class of logarithmic integrals

abstract:
  We present a systematic study of integrals over [0,1] where the integrand is
of the form Q(x) log log 1/x. Here Q is a rational function.


title:
The integrals in Gradshteyn and Ryzhik. Part 11: The incomplete beta
  function

abstract:
  The table of Gradshteyn and Ryzhik contains some integrals that can be
expressed in terms of the incomplete beta function. We describe some elementary
properties of this function and use them to check some of the formulas in the
mentioned table.


title: New stable phase of non uniform black strings in ${AdS}_d$

abstract:
  We consider the non uniform $AdS$ black string equations in arbitrary number
of dimension in a perturbative approach up to order 2 and in a non
perturbative. We restrict the study in the perturbative approach to the
backreacting modes, since they provide the first relevant corrections on the
thermodynamical quantities of the solutions. We also present some preliminary
results in the construction of non-perturbative solutions, in particular, we
present a first part of the non uniform - uniform black string phase diagram.
Our results suggests the existence of a new stable phase for $AdS$ non uniform
black strings, namely long non uniform black string, with the extra direction
length of the order of the $AdS$ curvature.


title: Exterior algebras and two conjectures on finite abelian groups

abstract:
  Let G be a finite abelian group with |G|>1. Let a_1,...,a_k be k distinct
elements of G and let b_1,...,b_k be (not necessarily distinct) elements of G,
where k is a positive integer smaller than the least prime divisor of |G|. We
show that there is a permutation $\pi$ on {1,...,k} such that
a_1b_{\pi(1)},...,a_kb_{\pi(k)} are distinct, provided that any other prime
divisor of |G| (if there is any) is greater than k!. This in particular
confirms the Dasgupta-Karolyi-Serra-Szegedy conjecture for abelian p-groups. We
also pose a new conjecture involving determinants and characters, and show that
its validity implies Snevily's conjecture for abelian groups of odd order. Our
methods involve exterior algebras and characters.


title:
Worlds Beyond: A Strategy for the Detection and Characterization of
  Exoplanets

abstract:
  This is a scientific strategy for the detection and characterization of
extrasolar planets; that is, planets orbiting other stars. As such, it maps out
over a 15-year horizon the techniques and capabilities required to detect and
measure the properties of planets as small as Earth around stars as large as
our own Sun. It shows how the technology pieces and their development fit
together to achieve the primary goal of the strategy: if planets like Earth
exist around stars within some tens of light years of our own Solar System,
those planets will be found and their basic properties characterized. Essential
to this strategy is not only the search for and examination of individual
planets, but also a knowledge of the arrangement, or architecture, of planetary
systems around as large a number of stars as possible; this is the second goal
of the strategy. The final goal of the strategy is the study of disks around
stars, important both to understand the implications of the variety of
exoplanet systems for planet formation, and to determine how many nearby stars
have environments around them clean enough of debris that planets may be sought
and, if found, characterized.


title: Exponential sums nondegenerate relative to a lattice

abstract:
  Our previous theorems on exponential sums often did not apply or did not give
sharp results when certain powers of a variable appearing in the polynomial
were divisible by p. We remedy that defect in this paper by systematically
applying "p-power reduction," making it possible to strengthen and extend our
earlier results.


title: Electrical probing of the spin conductance of mesoscopic cavities

abstract:
  We investigate spin-dependent transport in three--terminal mesoscopic
cavities with spin--orbit coupling. Focusing on the inverse spin Hall effect,
we show how injecting a pure spin current or a polarized current from one
terminal generates additional charge current and/or voltage across the two
output terminals. This allows to extract the spin conductance of the cavity
from two purely electrical measurements on the output. We use random matrix
theory to show that the spin conductance of chaotic ballistic cavities
fluctuates universally about zero mesoscopic average and describe experimental
implementations of mesoscopic spin to charge current converters.


title:
The evolution of anisotropic structures and turbulence in the
  multi-dimensional Burgers equation

abstract:
  The goal of the present paper is the investigation of the evolution of
anisotropic regular structures and turbulence at large Reynolds number in the
multi-dimensional Burgers equation. We show that we have local isotropization
of the velocity and potential fields at small scale inside cellular zones. For
periodic waves, we have simple decay inside of a frozen structure. The global
structure at large times is determined by the initial correlations, and for
short range correlated field, we have isotropization of turbulence. The other
limit we consider is the final behavior of the field, when the processes of
nonlinear and harmonic interactions are frozen, and the evolution of the field
is determined only by the linear dissipation.


title:
Effect of Coherent State of Quarks and Mesons on Hadron Properties in
  the Extended Linear Sigma Model

abstract:
  The extended chiral sigma model with quark fields and elementary pion and
sigma fields is used to describe static nucleon properties. The field equations
have been solved in coherent pair approximation. Better results are obtained
for nucleon properties in comparison with previous work and reasonably agree
with data.


title:
Anharmonic effect on lattice distortion, orbital ordering and magnetic
  properties in Cs2AgF4

abstract:
  We develop the cluster self-consistent field method incorporating both
electronic and lattice degrees of freedom to study the origin of ferromagnetism
in Cs$_{2}$AgF$_{4}$. After self-consistently determining the harmonic and
anharmonic Jahn-Teller distortions, we show that the anharmonic distortion
stabilizes the staggered x$^{2}$-z$^{2}$/y$^{2}$-z$^{2}$ orbital and
ferromagnetic ground state, rather than the antiferromagnetic one. The
amplitudes of lattice distortions, Q$_{2}$ and Q$_{3}$, the magnetic coupling
strengthes, J$_{x,y}$, and the magnetic moment, are in good agreement with the
experimental observation.


title:
Force and length-dependent catastrophe activities explain interphase
  microtubule organization in fission yeast

abstract:
  The cytoskeleton is essential for the maintenance of cell morphology in
eukaryotes. In fission yeast for example, polarized growth sites are organized
by actin whereas microtubules (MT) acting upstream control where growth occurs
(La Carbona et al, 2006). Growth is limited to the cell poles when MTs undergo
catastrophes there and not elsewhere on the cortex (Brunner and Nurse, 2000).
Here we report that the modulation of MT dynamics by forces as observed in
vitro (Dogterom and Yurke, 1997; Janson et al, 2003) can quantitatively explain
the localization of MT catastro-phes in S. pombe. However, we found that it is
necessary to add length-dependent catastrophe rates to make the model fully
consistent with other measured traits of MTs. This result demonstrates the
possibility that MTs together with associated proteins such as kinesins having
a depolymerization activity can reliably mark the tips of the cell.


title: On almost universal mixed sums of squares and triangular numbers

abstract:
  In 1997 K. Ono and K. Soundararajan [Invent. Math. 130(1997)] proved that
under the generalized Riemann hypothesis any positive odd integer greater than
2719 can be represented by the famous Ramanujan form $x^2+y^2+10z^2$,
equivalently the form $2x^2+5y^2+4T_z$ represents all integers greater than
1359, where $T_z$ denotes the triangular number $z(z+1)/2$. Given positive
integers $a,b,c$ we employ modular forms and the theory of quadratic forms to
determine completely when the general form $ax^2+by^2+cT_z$ represents
sufficiently large integers and establish similar results for the forms
$ax^2+bT_y+cT_z$ and $aT_x+bT_y+cT_z$. Here are some consequences of our main
theorems: (i) All sufficiently large odd numbers have the form $2ax^2+y^2+z^2$
if and only if all prime divisors of $a$ are congruent to 1 modulo 4. (ii) The
form $ax^2+y^2+T_z$ is almost universal (i.e., it represents sufficiently large
integers) if and only if each odd prime divisor of $a$ is congruent to 1 or 3
modulo 8. (iii) $ax^2+T_y+T_z$ is almost universal if and only if all odd prime
divisors of $a$ are congruent to 1 modulo 4. (iv) When $v_2(a)\not=3$, the form
$aT_x+T_y+T_z$ is almost universal if and only if all odd prime divisors of $a$
are congruent to 1 modulo 4 and $v_2(a)\not=5,7,...$, where $v_2(a)$ is the
2-adic order of $a$.


title: On the (ir)rationality of Kontsevich weights

abstract:
  We compute the weight of a Kontsevich graph in deformation quantization. Up
to rationals, the result is Zeta(3)^2/Pi^6.


title: Superconducting Properties of Two-Orbital t-t'-J-J' Models

abstract:
  Motivated by the recent contradiction of the superconducting pairing symmetry
in the angle-resolved photoemission spectra (ARPES) and the nuclear magnetic
resonance (NMR) data in the FeAs superconductors, we present the theoretical
results on the phase diagram, the temperature dependent Fermi surfaces in
normal state, the ARPES character of quasiparticles and the spin-lattice
relaxation 1/T$_{1}$ of the two-orbital t-t$^{'}$-J-J$^{'}$ models. Our results
show that most of the properties observed in iron-based superconductors could
be comprehensively understood in the present scenario qualitatively, indicating
that the pairing symmetry of the ironpnictides is anisotropic nodeless s-wave,
mainly originating from the band structures and the Fermi surface topology.


title:
Comment on "Generating Unexpected Spin Echoes in Dipolar Solids with Pi
  Pulses" arXiv:0705.0667

abstract:
  The present work is a comment on PRL 98, 190401 (2007), arXiv:0705.0667 . The
authors reported NMR measurements in solids with different pulse sequences. In
some multiple $\pi$ pulse echo trains they observed coherent signals of several
seconds, well beyond the Hahn echo decay, $T_{2HE}$ (few milliseconds). They
ascribed the long tails to coherent phenomena arising on the dipolar couplings
during any real finite NMR pulse. Their statement is based on some assumptions
that are incorrect and parameters in the calculations, that do not represent
the experimental conditions.


title: The impact of dynamical screening on the phonon dynamics of LaCuO

abstract:
  It is shown that dynamical screening of the Coulomb interaction in LaCuO
leads to low-energy electronic collective excitations in a small region around
the c-axis, strongly mixing with interlayer phonons. The manifestation of such
a phonon-plasmon scenario based on a nonadiabatic charge response is
quantitatively supported by a realistic calculation of the frequency and
wavevector dependent irreducible polarization part of the density response
function. The latter is used within linear response theory to calculate the
coupled mode dispersion in the main symmetry directions of the Brillouin zone
and the charge density redistributions excited by certain strongly coupling
phonon-like and plasmon-like modes. Moreover, the corresponding mode induced
orbital averaged changes of the selfconsistent potential felt by the electrons
are assessed. Our analysis should be representative for the optimally to
overdoped state of the cuprates where experimental evidence of a coherent
three-dimensional Fermi surface and a coherent c-axis charge transport is
given. It is demonstrated that modes from the outside of a small region around
the c-axis can reliably be calculated within the adiabatic limit. Only a minor
nonadiabatic correction is found for these modes in form of stiffening of the
high-frequency oxygen-bond-stretching mode at the X-point which is attributed
to dynamical reduced nesting. On the other hand, modes inside the nonadiabatic
sector of the BZ have to be determined nonadiabatically owing to the poor
dynamical screening of the long-ranged Coulomb interaction around the c-axis by
the slow charge dynamics. In particular, the relevance of the strongly coupling
phonon-like apex oxygen $Z$-point breathing mode at about 40 meV is emphasized
whose mode energy decreases with less doping.


title: Algebraic Values of Transcendental Functions at Algebraic Points

abstract:
  In this paper, the authors will prove that any subset of $\overline{\QQ}$ can
be the exceptional set of some transcendental entire function. Furthermore, we
could generalize this theorem to a much more general version and present a
unified proof.


title:
Simple Formula for High-Energy Gluon Bremsstrahlung in a Finite,
  Expanding Medium

abstract:
  Previous authors have considered the problem of the medium effects on single
gluon bremsstrahlung associated with producing a high-energy particle in a
finite, time-dependent QCD plasma. Working to leading logarithmic order, I show
that the result for the bremsstrahlung gluon spectrum can be cast into a
remarkably simple form in the general case. I similarly analyze the process of
pair production. Also, I comment on the radius of convergence of the opacity
expansion in cases where the leading-log approximation holds, showing that the
opacity expansion does not converge when the thickness of the plasma is greater
than roughly the bremsstrahlung formation time. Additionally, as a special
bonus -- available for a limited time only while supplies last! -- I summarize
translations between the notation used by a few of the groups who have worked
on this and related problems.


title: Conditions for the spin-spiral state in itinerant magnets

abstract:
  The spin-spiral (SS) type of magnetization is studied with the Hubbard model.
Consideration of noncollinearity of the magnetic moments results in a phase
diagram which consists of regions of the SS and paramagnetic states depending
on the number of electrons and the parameter U/t (U is the Hubbard repulsion,
and t is an overlap integral). A possibility of stabilization of the SS state
with three nonzero components of magnetic moment is considered.


title: Saturation physics and angular correlations at RHIC and LHC

abstract:
  We investigate the angular correlation between pions and photons produced in
deuteron-gold collisions at RHIC and proton-lead collisions at LHC using the
Color Glass Condensate formalism and make predictions for the dependence of the
production cross section on the angle between the pion and photon at different
rapidities and transverse momenta. Measuring this dependence would shed further
light on the role of high gluon density and saturation dynamics at RHIC and
LHC.


title:
Tidal Heating of Terrestrial Extra-Solar Planets and Implications for
  their Habitability

abstract:
  The tidal heating of hypothetical rocky (or terrestrial) extra-solar planets
spans a wide range of values depending on stellar masses and initial orbits.
Tidal heating may be sufficiently large (in many cases, in excess of radiogenic
heating) and long-lived to drive plate tectonics, similar to the Earth's, which
may enhance the planet's habitability. In other cases, excessive tidal heating
may result in Io-like planets with violent volcanism, probably rendering them
unsuitable for life. On water-rich planets, tidal heating may generate
sub-surface oceans analogous to Europa's with similar prospects for
habitability. Tidal heating may enhance the outgassing of volatiles,
contributing to the formation and replenishment of a planet's atmosphere. To
address these issues, we model the tidal heating and evolution of hypothetical
extra-solar terrestrial planets. The results presented here constrain the
orbital and physical properties required for planets to be habitable.


title:
Seiberg Duality in Chern-Simons Theories with Fundamental and Adjoint
  Matter

abstract:
  We explore the dynamics of three-dimensional Chern-Simons gauge theories with
N=2 supersymmetry and matter in the fundamental and adjoint representations of
the gauge group. Realizing the gauge theories of interest in a setup of
threebranes and fivebranes in type IIB string theory we argue for a Seiberg
duality that relates Chern-Simons theories with non-trivial superpotentials.


title:
Distinct pseudogap and superconducting state quasiparticle relaxation
  dynamics in near-optimally doped SmFeAsO0.8F0.2 single crystals

abstract:
  We use femtosecond spectroscopy to investigate the quasiparticle relaxation
and low-energy electronic structure in a near-optimally doped pnictide
superconductor with T_c=49.5 K. Multiple relaxation processes are evident, with
distinct superconducting state quasiparticle (QP) recombination dynamics
exhibiting a T-dependent superconducting (SC) gap, and a clear "pseudogap" (PG)
-like feature with an onset around 200K indicating the existence of a
temperature-independent gap of magnitude \Delta_PG= 61 +- 9 meV above T_c. Both
the SC and PG components show saturation as a function of fluence with distinct
saturation thresholds ~0.15 \muJ/cm^2 and 1.5 \muJ/cm^2, respectively.


title:
Seismic Activity of the Earth, the Cosmological Vectorial Potential And
  Method of a Short-term Earthquakes Forecasting

abstract:
  To the foundation of a principally new short-term forecasting method there
has been laid down a theory of surrounding us world's creation and of physical
vacuum as a result of interaction of byuons - discrete objects. The definition
of the byuon contains the cosmological vector-potential A_g - a novel
fundamental vector constant. This theory predicts a new anisotropic interaction
of nature objects with the physical vacuum. A peculiar "tap" to gain new energy
(giving rise to an earthquake) are elementary particles because their masses
are proportional to the modulus of some summary potential A_sum that contains
potentials of all known fields. The value of A_sum cannot be larger than the
modulus of A_g. In accordance with the experimental results a new force
associated with A_sum ejects substance from the area of the weakened A_sum
along a conical formation with the opening of 100 +- 10 and the axis directed
along the vector A_sum. This vector has the following coordinates in the second
equatorial coordinate system: right ascension alpha = 293 +- 10, declination
delta = 36 +- 10. Nearly 100% probability of an earthquake (earthquakes of 6
points strong and more by the Richter scale) arises when in the process of the
earth rotation the zenith vector of a seismically dangerous region and/or the
vectorial potential of Earth's magnetic fields are in a certain way oriented
relative to the vector A_g. In the work, basic models and standard mechanisms
of earthquakes are briefly considered, results of processing of information on
the earthquakes in the context of global spatial anisotropy caused by the
existence of the vector A_g, are presented, and an analysis of them is given.


title: How classical is the quantum universe?

abstract:
  We discuss two topics that are usually considered to be exclusively
"quantum": the Schroedinger equation, and the uncertainty principle. We show
(or rather recall) that the Schroedinger equation can be derived from
Hamilton's equations using the metaplectic representation. We also show that
the uncertainty principle, stated in the form of the
Robertson-Schroedinger-Heisenberg inequalities can be formulated in perfectly
classical terms using the topological notion of symplectic capacity.


title: Parallel approximation of non-interactive zero-sum quantum games

abstract:
  This paper studies a simple class of zero-sum games played by two competing
quantum players: each player sends a mixed quantum state to a referee, who
performs a joint measurement on the two states to determine the players'
payoffs. We prove that an equilibrium point of any such game can be
approximated by means of an efficient parallel algorithm, which implies that
one-turn quantum refereed games, wherein the referee is specified by a quantum
circuit, can be simulated in polynomial space.


title: Phases of Higher Dimensional Black Holes

abstract:
  We review some of the most striking properties of the phase diagrams of
higher dimensional black holes in pure gravity. We focus on static black hole
solutions with Kaluza-Klein asymptotics and stationary black hole solutions in
flat Minkowski space. Both cases exhibit a rich pattern of interconnected
phases and merger points with topology changing transitions. In the first case,
the phase diagram includes uniform and non-uniform black strings, localized
black holes and sequences of Kaluza-Klein bubbles. In the latter case, it
includes Myers-Perry black holes, black rings, black saturns and pinched black
holes.


title: On the Symmetries of Classical String Theory

abstract:
  I discuss some aspects of conformal defects and conformal interfaces in two
spacetime dimensions. Special emphasis is placed on their role as
spectrum-generating symmetries of classical string theory.


title:
Trajectory end point distribution of a test particle in a turbulent
  liquid

abstract:
  In a recent paper the mean square displacement (MSD), <R^2(T)>, of a particle
carried by a turbulent liquid over time T has been shown to be proportional to
T^6/5, meaning that the motion of the particle is slightly super-diffusive. In
some cases, though, it might be important to have more information than that
provided by that law. An example would be the distribution of pollutants as a
function of time by turbulent flow. Here small amounts of material reaching
relatively large distances are of importance. This motivates our interest in
the full distribution of the location of particles swept by the fluid as a
function of time. The distribution depends on the distance through the
dimensionless quantity X^2=R^2/<R^2(T)> . We find that for small X, the
distribution P(R,T) is proportional to exp(-aX^2) but at its tail when X is
large it behaves as exp(-bX^2/3) . pacs numbers-02.50.Ey, 05.40.Fb


title: Unifying Practical Uncertainty Representations: II. Clouds

abstract:
  There exist many simple tools for jointly capturing variability and
incomplete information by means of uncertainty representations. Among them are
random sets, possibility distributions, probability intervals, and the more
recent Ferson's p-boxes and Neumaier's clouds, both defined by pairs of
possibility distributions. In the companion paper, we have extensively studied
a generalized form of p-box and situated it with respect to other models . This
paper focuses on the links between clouds and other representations.
Generalized p-boxes are shown to be clouds with comonotonic distributions. In
general, clouds cannot always be represented by random sets, in fact not even
by 2-monotone (convex) capacities.


title:
Entropy production in temperature modulated differential scanning
  calorimetry

abstract:
  The non-equilibrium process due to irreversible heat exchanges occurring
during a temperature modulated differential scanning calorimetry experiment is
investigated in detail. This enables us to define an experimental frequency
dependent complex heat capacity from this calorimetric method. The physical
meaning of this dynamic heat capacity is discussed. A relationship is clearly
established between the imaginary part of this complex quantity and the net
entropy created during the experimental time-scale.


title: A note on the heat kernel coefficients for nonminimal operators

abstract:
  We consider certain results for the heat kernel of nonminimal operators. The
general expressions provided by Gusynin and Kornyak resulting from symbolic
computation programmes for n dimensions are evaluated for 4 dimensions which
are checked against results given by Barvinsky and Vilkovisky. We also check
that the results in flat space are consistent with earlier results of
Guendelmen et al. We then consider a powerful construction of the Green
function of a nonminimal operator by Shore for covariantly constantly gauge
fields in flat spacetime, and employ dimensional arguments to produce a check
on the gauge parameter dependence of a certain coefficient. The connection of
the results for heat kernel coefficients emanating from the construction of
Shore, to those from other techniques is hereby established for the first time.


title:
Deviations from Tri-bimaximal Mixing: Charged Lepton Corrections and
  Renormalization Group Running

abstract:
  We analyze the effects of charged lepton corrections and renormalization
group (RG) running on the low energy predictions of theories which accurately
predict tri-bimaximal neutrino mixing at the high energy scale. In particular
we focus on GUT inspired see-saw models with accurate tri-bimaximal neutrino
mixing at the GUT scale, in which the charged lepton corrections are
Cabibbo-like and give rise to sum rules valid at the GUT scale. We study
numerically the RG corrections to a variety of such neutrino mixing sum rules
in order to assess their accuracy and reliability when comparing them to future
low energy neutrino oscillation experiments. Our results indicate that the RG
corrections to neutrino mixing sum rules are typically small (less than one
degree), at least in the examples studied with hierarchical neutrinos.


title:
Bounds on variation of spectral subspaces under J-self-adjoint
  perturbations

abstract:
  Let $A$ be a self-adjoint operator on a Hilbert space $\fH$. Assume that the
spectrum of $A$ consists of two disjoint components $\sigma_0$ and $\sigma_1$.
Let $V$ be a bounded operator on $\fH$, off-diagonal and $J$-self-adjoint with
respect to the orthogonal decomposition $\fH=\fH_0\oplus\fH_1$ where $\fH_0$
and $\fH_1$ are the spectral subspaces of $A$ associated with the spectral sets
$\sigma_0$ and $\sigma_1$, respectively. We find (optimal) conditions on $V$
guaranteeing that the perturbed operator $L=A+V$ is similar to a self-adjoint
operator. Moreover, we prove a number of (sharp) norm bounds on variation of
the spectral subspaces of $A$ under the perturbation $V$. Some of the results
obtained are reformulated in terms of the Krein space theory. As an example,
the quantum harmonic oscillator under a PT-symmetric perturbation is discussed.

categories: math.SP math-ph math.MP physics.comp-ph quant-ph


title: Diffusion of wave packets in a Markov random potential

abstract:
  We consider the evolution of a tight binding wave packet propagating in a
time dependent potential. If the potential evolves according to a stationary
Markov process, we show that the square amplitude of the wave packet converges,
after diffusive rescaling, to a solution of a heat equation.


title:
Positivity and Kleiman transversality in equivariant K-theory of
  homogeneous spaces

abstract:
  We prove the conjectures of Graham-Kumar and Griffeth-Ram concerning the
alternation of signs in the structure constants for torus-equivariant K-theory
of generalized flag varieties G/P. These results are immediate consequences of
an equivariant homological Kleiman transversality principle for the Borel
mixing spaces of homogeneous spaces, and their subvarieties, under a natural
group action with finitely many orbits. The computation of the coefficients in
the expansion of the equivariant K-class of a subvariety in terms of Schubert
classes is reduced to an Euler characteristic using the homological
transversality theorem for non-transitive group actions due to S. Sierra. A
vanishing theorem, when the subvariety has rational singularities, shows that
the Euler characteristic is a sum of at most one term--the top one--with a
well-defined sign. The vanishing is proved by suitably modifying a geometric
argument due to M. Brion in ordinary K-theory that brings Kawamata-Viehweg
vanishing to bear.


title:
An interesting result concerning the lower bound to the energy in the
  Heisenberg picture

abstract:
  In quantum theory it is generally assumed that there exists a special state
called the vacuum state and that this state is a lower bound to the energy.
However it has recently been demonstrated that this is not necessarily the case
for some situations [5]. In order to clarify the situation we will consider a
"very simple" field theory in the Heisenberg picture consisting of a quanitized
fermion field with zero mass pariticles in 1-1D space-time interacting with a
classical electrical potential. It will be shown that for this example there is
no lower bound to the energy.


title: Core Formation in Giant Gaseous Protoplanets

abstract:
  Sedimentation rates of silicate grains in gas giant protoplanets formed by
disk instability are calculated for protoplanetary masses between 1 M_Saturn to
10 M_Jupiter. Giant protoplanets with masses of 5 M_Jupiter or larger are found
to be too hot for grain sedimentation to form a silicate core. Smaller
protoplanets are cold enough to allow grain settling and core formation. Grain
sedimentation and core formation occur in the low mass protoplanets because of
their slow contraction rate and low internal temperature. It is predicted that
massive giant planets will not have cores, while smaller planets will have
small rocky cores whose masses depend on the planetary mass, the amount of
solids within the body, and the disk environment. The protoplanets are found to
be too hot to allow the existence of icy grains, and therefore the cores are
predicted not to contain any ices. It is suggested that the atmospheres of low
mass giant planets are depleted in refractory elements compared with the
atmospheres of more massive planets. These predictions provide a test of the
disk instability model of gas giant planet formation.
  The core masses of Jupiter and Saturn were found to be ~0.25 M_Earth and ~0.5
M_Earth, respectively. The core masses of Jupiter and Saturn can be
substantially larger if planetesimal accretion is included. The final core mass
will depend on planetesimal size, the time at which planetesimals are formed,
and the size distribution of the material added to the protoplanet. Jupiter's
core mass can vary from 2 to 12 M_Earth. Saturn's core mass is found to be ~8
M_Earth.


title:
A mid-infrared study of HII regions in the Magellanic Clouds: N88A and
  N160A

abstract:
  To show the importance of high-spatial resolution observations of HII regions
when compared with observations obtained with larger apertures such as ISO, we
present mid-infrared spectra of two Magellanic Cloud HII regions, N88A and
N160A. We obtained mid-infrared (8-13 um), long-slit spectra with TIMMI2 on the
ESO 3.6m telescope. These are combined with archival spectra obtained with the
Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, and are
compared with the low-spatial resolution ISO-SWS data. An inventory of the
spectra in terms of atomic fine-structure lines and molecular bands is
presented. Concerning N88A, an isolated HII region with no adjacent infrared
sources, the observations indicate that the line fluxes observed by ISO-SWS and
Spitzer-IRS come exclusively from the compact HII region of about 3 arcsec in
diameter. This is not the case for N160A, which has a more complex morphology.
We have spectroscopically isolated for the first time the individual
contributions of the three components of N160A, two high-excitation blobs, A1
and A2, and the young stellar object N160A-IR. In addition, extended [SIV]
emission is observed with TIMMI2 and is most likely associated with the central
star cluster located between A1 and A2. We show the value of these high-spatial
resolution data in determining source characteristics, such as the degree of
ionization of each high-excitation blob or the bolometric luminosity of the
YSO. This luminosity is about one order of magnitude lower than previously
estimated. For each high-excitation blob, we also determine the electron
density and the elemental abundances of Ne, S, and Ar.


title:
Strongly t-logarithmic t-generating sets: Geometric properties of some
  soluble groups

abstract:
  We introduce the concept of a strongly t-logarithmic t-generating set for a
Z[t,t^{-1}]-module, which enables us to prove that a large class of soluble
groups are not almost convex. We also prove some results about dead-end depth.


title: On the formation and abundance of CO in AGB envelopes

abstract:
  It is generally considered, as a rule of thumb, that carbon monoxide forms
very early in envelopes of AGB stars, and that it consumes most of the carbon,
or most of the oxygen, depending on whether the photosphere is oxygen-rich or
carbon-rich, respectively. \rm This work focuses on the latter case, with the
purpose of quantifying the remaining fraction of gaseous carbon which is then
available for forming carbonaceous grains. Since AGB stars are (probably) the
main providers of cosmic carbon grains, this residual fraction is essential in
establishing the validity of current grain models. Here, we use a kinetic
treatment to follow the chemical evolution of circumstellar shells towards
steady state. It is shown that the residual fraction depends essentially on the
atomic ratio of pristine gaseous carbon and oxygen, and on the cross-section
for CH formation by collision of C and H atoms. It lies between 55 and 144 C
atoms per million H atoms, depending on the values adopted for unknown reaction
rates and cosmic C abundance. This is much larger than predicted by the rule of
thumb recalled above.
  The present results depend strongly on the rate of the reaction C+H-->CH: far
from thermodynamic equilibrium (which is the case here), CO cannot be formed if
this rate is as low as generally assumed. We have, therefore, estimated this
rate by chemically modelling the reaction and found it indeed much higher, and
high enough to yield CO abundances compatible with observations. An accurate
experimental rate determination is highly desirable.


title: Optical absorption from solvation-induced polarons on nanotubes

abstract:
  When an excess charge carrier is added to a one-dimensional (1D)
semiconductor immersed in a polar solvent, the carrier can undergo
self-localization into a large-radius adiabatic polaron. We explore the local
optical absorption from the ground state of 1D polarons using a simplified
theoretical model for small-diameter tubular structures. It is found that about
90% of the absorption strength is contained in the transition to the second
lowest-energy localized electronic level formed in the polarization potential
well, with the equilibrium transition energy larger than the binding energy of
the polaron. Thermal fluctuations, however, cause a very substantial -- an
order of magnitude larger than the thermal energy -- broadening of the
transition. The resulting broad absorption feature may serve as a signature for
the optical detection of solvated charge carriers.


title:
Breuil's classification of $p$-divisible groups over regular local rings
  of arbitrary dimension

abstract:
  Let $k$ be a perfect field of characteristic $p \geq 3$. We classify
$p$-divisible groups over regular local rings of the form
$W(k)[[t_1,...,t_r,u]]/(u^e+pb_{e-1}u^{e-1}+...+pb_1u+pb_0)$, where
$b_0,...,b_{e-1}\in W(k)[[t_1,...,t_r]]$ and $b_0$ is an invertible element.
This classification was in the case $r = 0$ conjectured by Breuil and proved by
Kisin.


title:
The Weibull - log Weibull transition of interoccurrence times for
  synthetic and natural earthquakes

abstract:
  We have studied interoccurrence time distributions by analyzing the synthetic
and three natural catalogs of the Japan Meteorological Agency (JMA), the
Southern California Earthquake Data Center (SCEDC), and Taiwan Central Weather
Bureau (TCWB) and revealed the universal feature of the interoccurrence time
statistics, Weibull - log Weibull transition. This transition reinforces the
view that the interoccurrence time statistics possess Weibull statistics and
log-Weibull statistics. Here in this paper, the crossover magnitude from the
superposition regime to the Weibull regime $m_c^2$ is proportional to the plate
velocity. In addition, we have found the region-independent relation,
$m_c^2/m_{max} = 0.54 \pm 0.004$.


title: Accelerating Scientific Computations with Mixed Precision Algorithms

abstract:
  On modern architectures, the performance of 32-bit operations is often at
least twice as fast as the performance of 64-bit operations. By using a
combination of 32-bit and 64-bit floating point arithmetic, the performance of
many dense and sparse linear algebra algorithms can be significantly enhanced
while maintaining the 64-bit accuracy of the resulting solution. The approach
presented here can apply not only to conventional processors but also to other
technologies such as Field Programmable Gate Arrays (FPGA), Graphical
Processing Units (GPU), and the STI Cell BE processor. Results on modern
processor architectures and the STI Cell BE are presented.


title: Locally Connected HL Compacta

abstract:
  It is consistent with MA plus not CH that there is a locally connected
hereditarily Lindelof compact space which is not metrizable.


title: Another forbidden solar oxygen abundance: the [O I] 5577 A line

abstract:
  Context: Recent works with improved model atmospheres, line formation, atomic
and molecular data, and detailed treatment of blends, have resulted in a
significant downward revision of the solar oxygen abundance.
  Aims: Considering the importance of the Sun as an astrophysical standard and
the current conflict of standard solar models using the new solar abundances
with helioseismological observations we have performed a new study of the solar
oxygen abundance based on the forbidden [OI] line at 5577.34 A, not previously
considered.
  Methods: High-resolution (R > 500 000), high signal-to-noise (S/N > 1000)
solar spectra of the [O I] 5577.34 A line have been analyzed employing both
three-dimensional (3D) and a variety of 1D (spatially and temporally averaged
3D, Holweger & Muller, MARCS and Kurucz models with and without convective
overshooting) model atmospheres.
  Results: The oxygen abundance obtained from the [OI] 5577.3 A forbidden line
is almost insensitive to the input model atmosphere and has a mean value of
A(O) = 8.71 +/- 0.02 (\sigma from using the different model atmospheres). The
total error (0.07 dex) is dominated by uncertainties in the log gf value (0.03
dex), apparent line variation (0.04 dex) and uncertainties in the continuum and
line positions (0.05 dex).
  Conclusions: The here derived oxygen abundance is close to the 3D-based
estimates from the two other [OI] lines at 6300 and 6363 A, the permitted OI
lines and vibrational and rotational OH transitions in the infrared. Our study
thus supports a low solar oxygen abundance (A(O) ~ 8.7), independent of the
adopted model atmosphere.


title: A remark on Khovanov homology and two-fold branched covers

abstract:
  Examples of knots and links distinguished by the total rank of their Khovanov
homology but sharing the same two-fold branched cover are given. As a result,
Khovanov homology does not yield an invariant of two-fold branched covers.


title: On satellites in semi-abelian categories: Homology without projectives

abstract:
  Working in a semi-abelian context, we use Janelidze's theory of generalised
satellites to study universal properties of the Everaert long exact homology
sequence. This results in a new definition of homology which does not depend on
the existence of projective objects. We explore the relations with other
notions of homology, and thus prove a version of the higher Hopf formulae. We
also work out some examples.


title: Curvature structure of self-dual 4-manifolds

abstract:
  We show the existence of a modified Cliff(1,1) structure compatible with an
Osserman 0-model of signature (2,2). We then apply this algebraic result to
certain classes of pseudo-Riemannian manifolds of signature (2,2). We obtain a
new characterization of the Weyl curvature tensor of an (anti-)self-dual
manifold and we prove some new results regarding (Jordan) Osserman manifolds.


title: Search for photon oscillations into massive particles

abstract:
  In this paper, we present the final results of our experiment on photon-axion
oscillations in the presence of a magnetic field, which took place at LULI
(Laboratoire pour l'Utilisation des Lasers Intenses, Palaiseau, France). Our
null measurement allowed us to exclude the existence of axions with inverse
coupling constant $M>9.\times 10^5$ GeV for low axion masses and to improve the
preceding BFRT limits by a factor 3 or more for axion masses $1.1 {meV}
<m_a<2.6 {meV}$. We also show that our experimental results improve the
existing limits on the parameters of a low mass hidden-sector boson usually
dubbed "paraphoton" because of its similarity with the usual photon.


title:
Discretized Multinomial Distributions and Nash Equilibria in Anonymous
  Games

abstract:
  We show that there is a polynomial-time approximation scheme for computing
Nash equilibria in anonymous games with any fixed number of strategies (a very
broad and important class of games), extending the two-strategy result of
Daskalakis and Papadimitriou 2007. The approximation guarantee follows from a
probabilistic result of more general interest: The distribution of the sum of n
independent unit vectors with values ranging over {e1, e2, ...,ek}, where ei is
the unit vector along dimension i of the k-dimensional Euclidean space, can be
approximated by the distribution of the sum of another set of independent unit
vectors whose probabilities of obtaining each value are multiples of 1/z for
some integer z, and so that the variational distance of the two distributions
is at most eps, where eps is bounded by an inverse polynomial in z and a
function of k, but with no dependence on n. Our probabilistic result specifies
the construction of a surprisingly sparse eps-cover -- under the total
variation distance -- of the set of distributions of sums of independent unit
vectors, which is of interest on its own right.


title:
Electro-optic and electrical properties in Hafnium-doped congruent
  lithium-niobate crystals

abstract:
  We report the optical and dielectric properties in hafnium (Hf)-doped lithium
niobate (LN) crystals. We investigated samples of congruent composition with
various doping concentration varying from 0 to 8 mol%. The clamped and
unclamped values of the electro-optic coefficient r 22 of Hf-doped LN and the
corresponding dielectric permittivity as well, have been experimentally
determined and compared with the results obtained in undoped congruent LN
crystals. We show that the electro-optic and dielectric properties are only
slightly affected by the introduction of hafnium ions, and therefore Hf-doped
LN has the advantage of low photorefractive damage compared with the undoped
congruent LN.


title: SPM Bulletin 25

abstract:
  Contents:
  1. Combinatorial and model-theoretical principles related to regularity of
ultrafilters and compactness of topological spaces, I; 2. Frechet-Urysohn fans
in free topological groups; 3. Packing index of subsets in Polish groups; 4.
Symmetric monochromatic subsets in colorings of the Lobachevsky plane; 5.
Structural Ramsey theory of metric spaces and topological dynamics of isometry
groups; 6. Distinguishing Number of Countable Homogeneous Relational
Structures; 7. Indestructible colourings and rainbow Ramsey theorems; 8.
Products of Borel subgroups; 9. Selection theorems and treeability; 10.
Combinatorial and model-theoretical principles related to regularity of
ultrafilters and compactness of topological spaces, IV; 11. A property of Cp[0,
1]; 12. A Dedekind Finite Borel Set; 13. Aronszajn Compacta; 14. A strong
antidiamond principle compatible with CH; 15. On the strength of Hausdorff's
gap condition; 16. Nonhomogeneous analytic families of trees; 17. Reasonable
non-Radon-Nikodym ideals; 18. Continuity and related forcing; 19. An exact
Ramsey principle for block sequences; 20. Baire reflection; 21. Tukey classes
of ultrafilters on; 22. Countably determined compact abelian groups; 23. A
topological reflection principle equivalent to Shelah's Strong Hypothesis; 24.
Superfilters, Ramsey theory, and van der Waerden's Theorem.


title:
A New Assumed Interaction. Experiments and Manifestations in
  Astrophysics

abstract:
  Results of experimental investigations of a new assumed interaction in nature
with the aid of high-current magnets, torsion and piezoresonance balances,
high-precision gravimeter, fluctuations in intensity of betta-decay of
radioactive elements, plasma devices and manifestations in astrophysics are
presented. A possible explanation of the results obtained based on a hypothesis
of global anisotropy of physical space caused by the existence of a
cosmological vectorial potential A_g, is given. It is shown that the vector A_g
has the following coordinates in the second equatorial coordinate system: right
ascension alpha = 293 +- 10, declination delta = 36 +- 10.


title: Inverse resonance scattering for Jacobi operators

abstract:
  We consider the Jacobi operator $(Jf)_n= a_{n-1}f_{n-1}+a_nf_{n+1}+b_nf_n$ on
$\Z$ with a real compactly supported sequences $(a_n-1)_{n\in\Z}$ and
$(b_n)_{n\in\Z}$. We give the solution of two inverse problems (including
characterization): $ (a,b)\to \{$zeros of the reflection coefficient$\}$ and
$(a,b)\to \{$bound states and resonances$\}$. We describe the set of
"iso-resonance operators $J$", i.e., all operators $J$ with the same resonances
and bound states.


title: Planar wallpaper group metamaterial for novel terahertz applications

abstract:
  We present novel metamaterial structures based upon various planar wallpaper
groups, in both hexagonal and square unit cells. An investigation of
metamaterials consisting of one, two, and three unique sub-lattices with
resonant frequencies in the terahertz (THz) was performed. We describe the
theory, and perform simulations and experiments to characterize these multiple
element metamaterials. A method for using these new structures as a means for
bio / chemical hazard detection, as well as electromagnetic signature control
is proposed.


title: High energy neutrinos from charm in astrophysical sources

abstract:
  Charm production gives rise to a flux of very high energy neutrinos from
astrophysical sources with jets driven by central engines, such as gamma ray
bursts or supernovae with jets. The neutrino flux from semi-leptonic decays of
charmed mesons is subject to much less hadronic and radiative cooling than the
conventional flux from pion and kaon decays and therefore has a dominant
contribution at higher energies, of relevance to future ultrahigh energy
neutrino experiments.


title: New spherically symmetric solutions in Einstein-Yang-Mills-Higgs model

abstract:
  We study classical solutions in the SU(2) Einstein-Yang-Mills-Higgs theory.
The spherically symmetric ans\"atze for all fields are given and the equations
of motion are derived as a system of ordinary differential equations. The
asymptotics and the boundary conditions at space origin for regular solutions
and at event horizon for black hole solutions are studied. Using the shooting
method, we found numerical solutions to the theory. For regular solutions, we
find two new sets of asymptotically flat solutions. Each of these sets contains
continua of solutions in the parameter space spanned by the shooting
parameters. The solutions bifurcate along these parameter curves and the
bifurcation are argued to be due to the internal structure of the model. Both
sets of the solutions are asymptotically flat but one is exponentially so and
the other is so with oscillations. For black holes, a new set of boundary
conditions is studied and it is found that there also exists a continuum of
black hole solutions in parameter space and similar bifurcation behavior is
also present to these solutions. The SU(2) charges of these solutions are found
zero and these solutions are proven to be unstable.


title: Monte Carlo Study of an Inhomogeneous Blume-Capel Model

abstract:
  Systems of particles in a confining potential exhibit a spatially dependent
density which fundamentally alters the nature of phase transitions that occur.
A specific instance of this situation, which is being extensively explored
currently, concerns the properties of ultra-cold, optically trapped atoms. Of
interest is how the superfluid-insulator transition is modified by the
inhomogeneity, and, indeed, the extent to which a sharp transition survives at
all. This paper explores a classical analog of these systems, the Blume-Capel
model with a spatially varying single ion anisotropy and/or temperature
gradient. We present results both for the nature of the critical properties and
for the validity of the "local density approximation" which is often used to
model the inhomogeneous case. We compare situations when the underlying uniform
transition is first and second order.


title:
Constraining the Surface Inhomogeneity and Settling Times of Metals on
  Accreting White Dwarfs

abstract:
  Due to the short settling times of metals in DA white dwarf atmospheres, any
white dwarfs with photospheric metals must be actively accreting. It is
therefore natural to expect that the metals may not be deposited uniformly on
the surface of the star. We present calculations showing how the temperature
variations associated with white dwarf pulsations lead to an observable
diagnostic of the surface metal distribution, and we show what constraints
current data sets are able to provide. We also investigate the effect that
time-variable accretion has on the metal abundances of different species, and
we show how this can lead to constraints on the gravitational settling times.


title: Holographic Systematics of D-brane Inflation

abstract:
  We provide a systematic treatment of possible corrections to the inflaton
potential for D-brane inflation in the warped deformed conifold. We consider
the D3-brane potential in the presence of the most general possible corrections
to the throat geometry sourced by coupling to the bulk of a compact Calabi-Yau
space. This corresponds to the potential on the Coulomb branch of the dual
gauge theory, in the presence of arbitrary perturbations of the Lagrangian. The
leading contributions arise from perturbations by the most relevant operators
that do not destroy the throat geometry. We find a generic contribution from a
non-chiral operator of dimension $\Delta=2$ associated with a global symmetry
current, resulting in a negative contribution to the inflaton mass-squared. If
the Calabi-Yau preserves certain discrete symmetries, this is the dominant
correction to the inflaton potential, and fine-tuning of the inflaton mass is
possible. In the absence of such discrete symmetries, the dominant contribution
comes from a chiral operator with $\Delta=3/2$, corresponding to a $\phi^{3/2}$
term in the inflaton potential. The resulting inflationary models are
phenomenologically similar to the inflection point scenarios arising from
specific D7-brane embeddings, but occur under far more general circumstances.
Our strategy extends immediately to other warped geometries, given sufficient
knowledge of the Kaluza-Klein spectrum.


title: Discovery of the Ultra-Bright Type II-L Supernova 2008es

abstract:
  We report the discovery by the Robotic Optical Transient Experiment
(ROTSE-IIIb) telescope of SN 2008es, an overluminous supernova (SN) at z=0.205
with a peak visual magnitude of -22.2. We present multiwavelength follow-up
observations with the Swift satellite and several ground-based optical
telescopes. The ROTSE-IIIb observations constrain the time of explosion to be
23+/-1 rest-frame days before maximum. The linear decay of the optical light
curve, and the combination of a symmetric, broad H\alpha emission line profile
with broad P Cygni H\beta and Na I \lambda5892 profiles, are properties
reminiscent of the bright Type II-L SNe 1979C and 1980K, although SN 2008es is
greater than 10 times more luminous. The host galaxy is undetected in
pre-supernova Sloan Digital Sky Survey images, and similar to Type II-L SN
2005ap (the most luminous SN ever observed), the host is most likely a dwarf
galaxy with M_r > -17. Swift Ultraviolet/Optical Telescope observations in
combination with Palomar photometry measure the SED of the SN from 200 to 800
nm to be a blackbody that cools from a temperature of 14,000 K at the time of
the optical peak to 6400 K 65 days later. The inferred blackbody radius is in
good agreement with the radius expected for the expansion speed measured from
the broad lines (10,000 km/s). The bolometric luminosity at the optical peak is
2.8 x 10^44 erg/s, with a total energy radiated over the next 65 days of 5.6 x
10^50 erg. We favor a model in which the exceptional peak luminosity is a
consequence of the core-collapse explosion of a progenitor star with a low-mass
extended hydrogen envelope and a stellar wind with a density close to the upper
limit on the mass-loss rate measured from the lack of an X-ray detection by the
Swift X-Ray Telescope. (Abridged).


title: Is there an upper limit to black hole masses?

abstract:
  We make a case for the existence for ultra-massive black holes (UMBHs) in the
Universe, but argue that there exists a likely upper limit to black hole masses
of the order of $M \sim 10^{10} \msun$. We show that there are three strong
lines of argument that predicate the existence of UMBHs: (i) expected as a
natural extension of the observed black hole mass bulge luminosity relation,
when extrapolated to the bulge luminosities of bright central galaxies in
clusters; (ii) new predictions for the mass function of seed black holes at
high redshifts predict that growth via accretion or merger-induced accretion
inevitably leads to the existence of rare UMBHs at late times; (iii) the local
mass function of black holes computed from the observed X-ray luminosity
functions of active galactic nuclei predict the existence of a high mass tail
in the black hole mass function at $z = 0$. Consistency between the optical and
X-ray census of the local black hole mass function requires an upper limit to
black hole masses. This consistent picture also predicts that the slope of the
$M_{\rm bh}$-$\sigma$ relation will evolve with redshift at the high mass end.
Models of self-regulation that explain the co-evolution of the stellar
component and nuclear black holes naturally provide such an upper limit. The
combination of multi-wavelength constraints predicts the existence of UMBHs and
simultaneously provides an upper limit to their masses. The typical hosts for
these local UMBHs are likely the bright, central cluster galaxies in the nearby
Universe.


title: Top quark induced vacuum misalignment in little higgs models

abstract:
  We show that the effect of the top quark can dominate over the effect of the
gauge sector in determining the vacuum alignment in little higgs (LH) models.
We demonstrate that in the littlest LH model and the SU(2)xSU(2)xU(1) LH model,
ensuring that the correct vacuum alignment is chosen requires that a subset of
the gauge sector couplings be large to overcome the effect of the top quark. We
quantify this effect by deriving bounds on the couplings in the gauge sector
and demonstrate that these bounds provide a compelling theoretical reason for
the gauge coupling constant hierarchy in the SU(2)xSU(2)xU(1) model that
reduces the Goldstone decay constant scale to a TeV. We also argue that for a
class of LH models with T parity the top quark drives the correct vacuum
alignment and therefore all gauge couplings can be small.


title: Tracing high density gas in M 82 and NGC 4038

abstract:
  We present the first detection of CS in the Antennae galaxies towards the NGC
4038 nucleus, as well as the first detections of two high-J (5-4 and 7-6) CS
lines in the center of M 82. The CS(7-6) line in M 82 shows a profile that is
surprisingly different to those of other low-J CS transitions we observed. This
implies the presence of a separate, denser and warmer molecular gas component.
The derived physical properties and the likely location of the CS(7-6) emission
suggests an association with the supershell in the centre of M 82.


title: The nature of faint Spitzer-selected dust-obscured galaxies

abstract:
  We use deep far-IR, submm, radio and X-ray imaging and mid-IR spectroscopy to
explore the nature of a sample of Spitzer-selected dust-obscured galaxies
(DOGs) in GOODS-N. A sample of 79 galaxies satisfy the criteria R-[24]>14
(Vega) down to S24>100 microJy. Twelve of these galaxies have IRS spectra
available which we use to measure redshifts and classify these objects as being
dominated by star formation or active galactic nuclei (AGN) activity in the
mid-IR. The IRS spectra and Spitzer photometric redshifts confirm that the DOGs
lie in a tight redshift distribution around z~2. Based on mid-IR colors, 80% of
DOGs are likely dominated by star formation; the stacked X-ray emission from
this sub-sample of DOGs is also consistent with star formation. Since only a
small number of DOGs are individually detected at far-IR and submm wavelengths,
we use a stacking analysis to determine the average flux from these objects and
plot a composite IR (8-1000 microns) spectral energy distribution (SED). The
average luminosity of these star forming DOGs is LIR~1e12 Lsun. We compare the
average star forming DOG to the average bright (S850>5 mJy) submillimeter
galaxy (SMG); the S24>100 microJy DOGs are 3 times more numerous but 8 times
less luminous in the IR. The far-IR SED shape of DOGs is similar to that of
SMGs (average dust temperature of around 30 K) but DOGs have a higher mid-IR to
far-IR flux ratio. The average star formation-dominated DOG has a star
formation rate of 200 Msun/yr which, given their space density, amounts to a
contribution of 0.01 Msun/yr/Mpc3 (or 5-10%) to the star formation rate density
at z~2. We use the composite SED to predict the average flux of DOGs in future
Herschel/PACS 100 micron and SCUBA-2 450 micron surveys and show that the
majority of them will be detected.