title:
Non-equilibrium processes: driven lattice gases, interface dynamics, and
  quenched disorder effects on density profiles and currents

abstract:
  Properties of the one-dimensional totally asymmetric simple exclusion process
(TASEP), and their connection with the dynamical scaling of moving interfaces
described by a Kardar-Parisi-Zhang (KPZ) equation are investigated. With
periodic boundary conditions, scaling of interface widths (the latter defined
via a discrete occupation-number-to-height mapping), gives the exponents
$\alpha=0.500(5)$, $z=1.52(3)$, $\beta=0.33(1)$. With open boundaries, results
are as follows: (i) in the maximal-current phase, the exponents are the same as
for the periodic case, and in agreement with recent Bethe ansatz results; (ii)
in the low-density phase, curve collapse can be found to a rather good extent,
with $\alpha=0.497(3)$, $z=1.20(5)$, $\beta=0.41(2)$, which is apparently at
variance with the Bethe ansatz prediction $z=0$; (iii) on the coexistence line
between low- and high- density phases, $\alpha=0.99(1)$, $z=2.10(5)$,
$\beta=0.47(2)$, in relatively good agreement with the Bethe ansatz prediction
$z=2$. From a mean-field continuum formulation, a characteristic relaxation
time, related to kinematic-wave propagation and having an effective exponent
$z^\prime=1$, is shown to be the limiting slow process for the low density
phase, which accounts for the above-mentioned discrepancy with Bethe ansatz
results. For TASEP with quenched bond disorder, interface width scaling gives
$\alpha=1.05(5)$, $z=1.7(1)$, $\beta=0.62(7)$. From a direct analytic approach
to steady-state properties of TASEP with quenched disorder, closed-form
expressions for the piecewise shape of averaged density profiles are given, as
well as rather restrictive bounds on currents. All these are substantiated in
numerical simulations.


title: Black holes as antimatter factories

abstract:
  We consider accretion of matter onto a low mass black hole surrounded by
ionized medium. We show that, because of higher mobility of protons than
electrons, the black hole would acquire positive electric charge. If the black
hole's mass is about or below $10^{20}$ g, the electric field at the horizon
can reach the critical value which leads to vacuum instability and
electron--positron pair production by the Schwinger mechanism. Since the
positrons are ejected by the emergent electric field, while electrons are
back--captured, the black hole operates as an antimatter factory which
effectively converts protons into positrons.


title: The "True" Column Density Distribution in Star-Forming Molecular Clouds

abstract:
  We use the COMPLETE Survey's observations of the Perseus star-forming region
to assess and intercompare three methods for measuring column density in
molecular clouds: extinction mapping (NIR); thermal emission mapping (FIR); and
mapping the intensity of CO isotopologues. The structures shown by all three
tracers are morphologically similar, but important differences exist.
Dust-based measures give similar, log-normal, distributions for the full
Perseus region, once careful calibration corrections are made. We also compare
dust- and gas-based column density distributions for physically-meaningful
sub-regions of Perseus, and we find significant variations in the distributions
for those regions. Even though we have used 12CO data to estimate excitation
temperatures, and we have corrected for opacity, the 13CO maps seem unable to
give column distributions that consistently resemble those from dust measures.
We have edited out the effects of the shell around the B-star HD 278942. In
that shell's interior and in the parts where it overlaps the molecular cloud,
there appears to be a dearth of 13CO, likely due either to 13CO not yet having
had time to form in this young structure, and/or destruction of 13CO in the
molecular cloud. We conclude that the use of either dust or gas measures of
column density without extreme attention to calibration and artifacts is more
perilous than even experts might normally admit. And, the use of 13CO to trace
total column density in detail, even after proper calibration, is unavoidably
limited in utility due to threshold, depletion, and opacity effects. If one's
main aim is to map column density, then dust extinction seems the best probe.
Linear fits amongst column density tracers are given, quantifying the inherent
uncertainties in using one tracer (when compared with others). [abridged]


title: Stabilization of Three-Dimensional Collective Motion

abstract:
  This paper proposes a methodology to stabilize relative equilibria in a model
of identical, steered particles moving in three-dimensional Euclidean space.
Exploiting the Lie group structure of the resulting dynamical system, the
stabilization problem is reduced to a consensus problem on the Lie algebra. The
resulting equilibria correspond to parallel, circular and helical formations.
We first derive the stabilizing control laws in the presence of all-to-all
communication. Providing each agent with a consensus estimator, we then extend
the results to a general setting that allows for unidirectional and
time-varying communication topologies.


title: Abundance gradients in the galactic disk: space and time variations

abstract:
  Recent work on abundance gradients have focussed not only on their
magnitudes, but also on their spatial and temporal variations. In this work, we
analyze the behaviour of radial abundance gradients in the galactic disk giving
special emphasis on these variations. The data used includes planetary nebulae
and objects in different age brackets, namely open clusters, HII regions,
cepheid variables and stars in OB associations. We find evidences for a space
variation of the radial gradients as measured for element ratios such as O/H,
S/H, Ne/H, Ar/H and [Fe/H], in the sense that the gradients tend to flatten out
at large galactocentric distances. Moreover, near the bulge-disk interface a
steep decrease in the abundances is observed. The time evolution of the
gradients is also evaluated on the basis of approximate ages attributed to the
central stars of planetary nebulae and open cluster stars. It is concluded that
the available data is consistent with a time flattening of the gradients during
the last 6 to 8 Gyr, a time interval in which the age determinations are
probably more accurate.


title:
Log minimal model program for the moduli space of stable curves: The
  first flip

abstract:
  We give a geometric invariant theory (GIT) construction of the log canonical
model $\bar M_g(\alpha)$ of the pairs $(\bar M_g, \alpha \delta)$ for $\alpha
\in (7/10 - \epsilon, 7/10]$ for small $\epsilon \in \mathbb Q_+$. We show that
$\bar M_g(7/10)$ is isomorphic to the GIT quotient of the Chow variety
bicanonical curves; $\bar M_g(7/10-\epsilon)$ is isomorphic to the GIT quotient
of the asymptotically-linearized Hilbert scheme of bicanonical curves. In each
case, we completely classify the (semi)stable curves and their orbit closures.
Chow semistable curves have ordinary cusps and tacnodes as singularities but do
not admit elliptic tails. Hilbert semistable curves satisfy further conditions,
e.g., they do not contain elliptic bridges. We show that there is a small
contraction $\Psi: \bar M_g(7/10+\epsilon) \to \bar M_g(7/10)$ that contracts
the locus of elliptic bridges. Moreover, by using the GIT interpretation of the
log canonical models, we construct a small contraction $\Psi^+ : \bar
M_g(7/10-\epsilon) \to \bar M_g(7/10)$ that is the Mori flip of $\Psi$.


title: Soft Elasticity in Nematic Liquid-Crystal Networks

abstract:
  Liquid-crystal networks consist of weakly crosslinked polymers that are
coupled to liquid-crystal molecules. The resultant hybrid system has rich
elastic properties. We develop a phase field model to describe mechanical
properties of a hexagonal liquid-crystal network. The hexagonal liquid-crystal
network is found to have soft shear deformations. The elastic properties are
predicted analytically and confirmed with numerical simulations. In addition
the model incorporates non-linear elasticity and dislocations or disclinations.


title:
Spin injection from Fe into Si(001): ab initio calculations and role of
  the Si complex band structure

abstract:
  We study the possibility of spin injection from Fe into Si(001), using the
Schottky barrier at the Fe/Si contact as tunneling barrier. Our calculations
are based on density-functional theory for the description of the electronic
structure and on a Landauer-Buttiker approach for the current. The
current-carrying states correspond to the six conduction band minima of Si,
which, when projected on the (001) surface Brillouin zone (SBZ), form five
conductance hot spots: one at the SBZ center and four symmetric satellites. The
satellites yield a current polarization of about 50%, while the SBZ center can,
under very low gate voltage, yield up to almost 100%, showing a zero-gate
anomaly. This extremely high polarization is traced back to the symmetry
mismatch of the minority-spin Fe wavefunctions to the conduction band
wavefunctions of Si at the SBZ center. The tunneling current is determined by
the complex band structure of Si in the [001] direction, which shows
qualitative differences compared to that of direct-gap semiconductors.
Depending on the Fermi level position and Schottky barrier thickness, the
complex band structure can cause the contribution of the satellites to be
orders of magnitude higher or lower than the central contribution. Thus, by
appropriate tuning of the interface properties, there is a possibility to cut
off the satellite contribution and to reach high injection efficiency. Also, we
find that a moderate strain of 0.5% along the [001] direction is sufficient to
lift the degeneracy of the pockets so that only states at the zone center can
carry current.


title: Aggregation of magnetic holes in a rotating magnetic field

abstract:
  We have experimentally investigated field induced aggregation of nonmagnetic
particles confined in a magnetic fluid layer when rotating magnetic fields were
applied. After application of a magnetic field rotating in the plane of the
fluid layer, the single particles start to form two-dimensional (2D) clusters,
like doublets, triangels, and more complex structures. These clusters
aggregated again and again to form bigger clusters. During this nonequilibrium
process, a broad range of cluster sizes was formed, and the scaling exponents,
$z$ and $z'$, of the number of clusters $N(t)\sim t^{z'}$and average cluster
size $S(t)\sim t^{z}$ were calculated. The process could be characterized as
diffusion limited cluster-cluster aggregation. We have found that all sizes of
clusters that occured during an experiment, fall on a single curve as the
dynamic scaling theory predicts. Hovewer, the characteristic scaling exponents
$z',\: z$ and crossover exponents $\Delta$ were not universal. A particle
tracking method was used to find the dependence of the diffusion coefficients
$D_{s}$ on cluster size $s$. The cluster motions show features of
\textit{\emph{Brownian}} motion. The average diffusion coefficients $<D_{s}>$
depend on the cluster sizes $s$ as a power law $<D_{s}>\propto s^{\gamma}$
where values of $\gamma$ as different as $\gamma=-0.62\pm0.19$ and
$\gamma=-2.08\pm0. were found in two of the experiments.


title: Detecting entanglement in two mode squeezed states by particle counting

abstract:
  We present an entanglement criterion for two mode squeezed states which
relies on particle counting only. The proposed inequality is optimal for the
state under consideration and robust against particle losses up to 2/3. As it
does not involve measurements of quadratures - which is typically very
challenging for atomic modes - it renders the detection of atomic many-particle
entanglement feasible in many different settings. Moreover it bridges the gap
between entanglement verification for a qubit and criteria for continuous
variables measured by homodyne detection. We illustrate its application in the
context of superradiant light scattering from Bose Einstein condensates by
considering the creation of entanglement between atoms and light as well as
between two condensates in different momentum states. The latter scheme takes
advantage of leaving the Gaussian realm and features probabilistic entanglement
distillation.


title:
Shape derivative of potential energy and energy release rate in fracture
  mechanics

abstract:
  We study general mathematical framework for variation of potential energy
with respect to domain deformation. It enables rigorous derivation of the
integral formulas for the energy release rate in crack problems. Applying a
technique of the shape sensitivity analysis, we formulate the shape derivative
of potential energy as a variational problem with a parameter. Key tools of our
abstract theory are a new parameter variational principle and the classical
implicit function theorem in Banach spaces.


title: One light composite Higgs boson facing electroweak precision tests

abstract:
  We study analytically and numerically the bounds imposed by the electroweak
precision tests on a minimal composite Higgs model. The model is based on
spontaneous SO(5)/SO(4) breaking, so that an approximate custodial symmetry is
preserved. The Higgs arises as a pseudo-Goldstone boson at a scale below the
electroweak symmetry breaking scale. We show that one can satisfy the
electroweak precision constraints without much fine-tuning. This is the case if
the left-handed top quark is fully composite, which gives a mass spectrum
within the reach of the LHC. However a composite top quark is strongly
disfavoured by flavour physics. The alternative is to have a singlet top
partner at a scale much lighter than the rest of the composite fermions. In
this case the top partner would be light enough to be produced significantly at
the LHC.


title: On The Existence of Globally Solvable Vector Fields in Smooth Manifolds

abstract:
  Let $(\mathrm{M}, \omega_{0})$ be a connected paracompact smooth oriented
manifold. We establish a necessary and sufficient conditions on Lie subalgebra
$\mathfrak{a}$ of $\mathrm{T M}$ such that its orbits becomes diffeomorphic to
an open convex set of $\mathbb{R}^{n}$, where $n$ is the orbit dimension.


title: Conjugate Generators of Knot and Link Groups

abstract:
  This note shows that if two elements of equal trace (e.g., conjugate
elements) generate an arithmetic two-bridge knot or link group, then the
elements are parabolic. This includes the figure-eight knot and Whitehead link
groups. Similarly, if two conjugate elements generate the trefoil knot group,
then the elements are peripheral.


title: The Fermi surface of Ba(1-x)K(x)Fe2As2 and its evolution with doping

abstract:
  We use angle-resolved photoemission spectroscopy (ARPES) to investigate the
electronic properties of the newly discovered iron-arsenic superconductor,
Ba(1-x)K(x)Fe2As2 and non-supercondcuting BaFe2As2. Our study indicates that
the Fermi surface of the undoped, parent compound BaFe$_2$As$_2$ consists of
hole pocket(s) at Gamma (0,0) and larger electron pocket(s) at X (1,0), in
general agreement with full-potential linearized plane wave (FLAPW)
calculations. Upon doping with potassium, the hole pocket expands and the
electron pocket becomes smaller with its bottom approaching the chemical
potential. Such an evolution of the Fermi surface is consistent with hole
doping within a rigid band shift model. Our results also indicate that FLAPW
calculation is a reasonable approach for modeling the electronic properties of
both undoped and K-doped iron arsenites.


title: Spectrum of Higgsonium in the SM and beyond

abstract:
  Using the formalism of Bethe-Salpeter equation (BSE) the Higgsonium bound
state is studied. The condition for formation of Higgsonium bound states are
discussed in SM and in the simple extension of.


title: Role of multifragmentation in spallation reactions

abstract:
  In nuclear reactions induced by hadrons and ions of high energies, nuclei can
disintegrate into many fragments during a short time (~100 fm/c). This
phenomenon known as nuclear multifragmentation was under intensive
investigation last 20 years. It was established that multifragmentation is an
universal process taking place in all reactions when the excitation energy
transferred to nuclei is high enough, more than 3 MeV per nucleon,
independently on the initial dynamical stage of the reactions. Very known
compound nucleus decay processes (sequential evaporation and fission), which
are usual for low energies, disappear and multifragmentation dominates at high
excitation energy. For this reason, calculation of multifragmentation must be
carried on in all cases when production of highly excited nuclei is expected,
including spallation reactions. From the other hand, one can consider
multifragmentation as manifestation of the liquid-gas phase transition in
finite nuclei. This gives way for studying nuclear matter at subnuclear
densities and for applications of properties of nuclear matter extracted from
multifragmentation reactions in astrophysics. In this contribution, the
Statistical Multifragmentation Model (SMM), which combines the compound nucleus
processes at low energies and multifragmentation at high energies, is
described. The most important ingredients of the model are discussed.


title: On Computing the Vertex Centroid of a Polyhedron

abstract:
  Let $\mathcal{P}$ be an $\mathcal{H}$-polytope in $\mathbb{R}^d$ with vertex
set $V$. The vertex centroid is defined as the average of the vertices in $V$.
We prove that computing the vertex centroid of an $\mathcal{H}$-polytope is
#P-hard. Moreover, we show that even just checking whether the vertex centroid
lies in a given halfspace is already #P-hard for $\mathcal{H}$-polytopes. We
also consider the problem of approximating the vertex centroid by finding a
point within an $\epsilon$ distance from it and prove this problem to be
#P-easy by showing that given an oracle for counting the number of vertices of
an $\mathcal{H}$-polytope, one can approximate the vertex centroid in
polynomial time. We also show that any algorithm approximating the vertex
centroid to \emph{any} ``sufficiently'' non-trivial (for example constant)
distance, can be used to construct a fully polynomial approximation scheme for
approximating the centroid and also an output-sensitive polynomial algorithm
for the Vertex Enumeration problem. Finally, we show that for unbounded
polyhedra the vertex centroid can not be approximated to a distance of
$d^{{1/2}-\delta}$ for any fixed constant $\delta>0$.


title:
An Integrated Picture of Star Formation, Metallicity Evolution, and
  Galactic Stellar Mass Assembly

abstract:
  We present an integrated study of star formation and galactic stellar mass
assembly from z=0.05-1.5 and galactic metallicity evolution from z=0.05-0.9
using a very large and highly spectroscopically complete sample selected by
rest-frame NIR bolometric flux in the GOODS-N. We assume a Salpeter IMF and fit
Bruzual & Charlot (2003) models to compute the galactic stellar masses and
extinctions. We determine the expected formed stellar mass density growth rates
produced by star formation and compare them with the growth rates measured from
the formed stellar mass functions by mass interval. We show that the growth
rates match if the IMF is slightly increased from the Salpeter IMF at
intermediate masses (~10 solar masses). We investigate the evolution of galaxy
color, spectral type, and morphology with mass and redshift and the evolution
of mass with environment. We find that applying extinction corrections is
critical when analyzing galaxy colors; e.g., nearly all of the galaxies in the
green valley are 24um sources, but after correcting for extinction, the bulk of
the 24um sources lie in the blue cloud. We find an evolution of the
metallicity-mass relation corresponding to a decrease of 0.21+/-0.03 dex
between the local value and the value at z=0.77 in the 1e10-1e11 solar mass
range. We use the metallicity evolution to estimate the gas mass of the
galaxies, which we compare with the galactic stellar mass assembly and star
formation histories. Overall, our measurements are consistent with a galaxy
evolution process dominated by episodic bursts of star formation and where star
formation in the most massive galaxies (>1e11 solar masses) ceases at z<1.5
because of gas starvation. (Abstract abridged)


title:
The effective theory of type IIA AdS4 compactifications on nilmanifolds
  and cosets

abstract:
  We consider string theory compactifications of the form AdS4 x M6 with
orientifold six-planes, where M6 is a six-dimensional compact space that is
either a nilmanifold or a coset. For all known solutions of this type we obtain
the four-dimensional N=1 low energy effective theory by computing the
superpotential, the Kaehler potential and the mass spectrum for the light
moduli. For the nilmanifold examples we perform a cross-check on the result for
the mass spectrum by calculating it alternatively from a direct Kaluza-Klein
reduction and find perfect agreement. We show that in all but one of the coset
models all moduli are stabilized at the classical level. As an application we
show that all but one of the coset models can potentially be used to bypass a
recent no-go theorem against inflation in type IIA theory.


title:
The Evolution of the M_BH-sigma relation Inferred from the Age
  Distribution of Local Early-Type Galaxies and AGN Evolution

abstract:
  We utilize the local velocity dispersion function (VDF) of spheroids,
together with their inferred age--distributions, to predict the VDF at higher
redshifts (0<z<6), under the assumption that (i) most of the stars in each
nearby spheroid formed in a single episode, and (ii) the velocity dispersion
sigma remained nearly constant afterward. We assume further that a supermassive
black hole (BH) forms concurrently with the stars, and within ~1 Gyr of the
formation of the potential well of the spheroid, and that the relation between
the mass of the BH and host velocity dispersion maintains the form M_BH ~
sigma^{beta} with beta~4, but with the normalization allowed to evolve with
redshift as ~(1+z)^{alpha}. We compute the BH mass function associated with the
VDF at each redshift, and compare the accumulated total BH mass density with
that inferred from the integrated quasar luminosity function (LF; the
so--called Soltan argument). This comparison is insensitive to the assumed duty
cycle or Eddington ratio of quasar activity, and we find that the match between
the two BH mass densities favors a relatively mild redshift evolution, with
alpha ~ 0.26, with a positive evolution as strong as alpha>1.3 excluded at the
99% confidence level. A direct match between the characteristic BH mass in the
VDF--based and quasar LF--based BH mass functions also yields a mean Eddington
ratio of lambda ~ 0.5-1 that is roughly constant within 0<z<3. A strong
positive evolution in the M_BH-sigma relation is still allowed by the data if
galaxies increase, on average, their velocity dispersions since the moment of
formation, due to dissipative processes. If we assume that the mean velocity
dispersion of the host galaxies evolves as sigma(z)=sigma(0)*(1+z)^{-gamma}, we
find a lower limit of gamma>0.23 for alpha>1.5. abridged


title:
Effects of metal enrichment and metal cooling in galaxy growth and
  cosmic star formation history

abstract:
  We present the results of a numerical study on the effects of metal
enrichment and metal cooling on galaxy formation and cosmic star formation (SF)
history using cosmological hydrodynamic simulations. We find following
differences in the simulation with metal cooling when compared to the run
without it: (1) the cosmic star formation rate (SFR) is enhanced by about 50 &
20% at z=1 & 3, respectively; (2) the gas mass fraction in galaxies is lower;
(3) the total baryonic mass function (gas + star) at z=3 does not differ
significantly, but shows an increase in the number of relatively massive
galaxies at z=1; (4) the baryonic mass fraction of intergalactic medium (IGM)
is reduced at z<3 due to more efficient cooling and gas accretion onto
galaxies. Our results suggest that the metal cooling enhances the galaxy growth
by two different mechanisms: (1) increase of SF efficiency in the local
interstellar medium (ISM), and (2) increase of IGM accretion onto galaxies. The
former process is effective throughout most of the cosmic history, while the
latter is effective only at z<3 when the IGM is sufficiently enriched by metals
owing to feedback.


title:
Physical approximations for the nonlinear evolution of perturbations in
  dark energy scenarios

abstract:
  The abundance and distribution of collapsed objects such as galaxy clusters
will become an important tool to investigate the nature of dark energy and dark
matter. Number counts of very massive objects are sensitive not only to the
equation of state of dark energy, which parametrizes the smooth component of
its pressure, but also to the sound speed of dark energy as well, which
determines the amount of pressure in inhomogeneous and collapsed structures.
Since the evolution of these structures must be followed well into the
nonlinear regime, and a fully relativistic framework for this regime does not
exist yet, we compare two approximate schemes: the widely used spherical
collapse model, and the pseudo-Newtonian approach. We show that both
approximation schemes convey identical equations for the density contrast, when
the pressure perturbation of dark energy is parametrized in terms of an
effective sound speed. We also make a comparison of these approximate
approaches to general relativity in the linearized regime, which lends some
support to the approximations.


title:
Atomic Structures of Riboflavin (Vitamin B2) and its Reduced Form with
  Bond Lengths Based on Additivity of Atomic Radii

abstract:
  It has been shown recently that chemical bond lengths, in general, like those
in the components of nucleic acids, caffeine related compounds, all essential
amino acids, methane, benzene, graphene and fullerene are sums of the radii of
adjacent atoms constituting the bond. Earlier, the crystal ionic distances in
all alkali halides and lengths of many partially ionic bonds were also
accounted for by the additivity of ionic as well as covalent radii. Here, the
atomic structures of riboflavin and its reduced form are presented based on the
additivity of the same set of atomic radii as for other biological molecules.


title: $\zeta$-phenomenology

abstract:
  It is well known that Euler experimentally discovered the functional equation
of the Riemann zeta function. Indeed he detected the fundamental $s\mapsto 1-s$
invariance of $\zeta(s)$ by looking only at special values. In particular, via
this functional equation, the permutation group on two letters,
$S_2\simeq\Z/(2)$, is realized as a group of symmetries of $\zeta(s)$. In this
paper, we use the theory of special-values of our characteristic $p$ zeta
functions to experimentally detect a natural symmetry group $S_{(q)}$ for these
functions of cardinality ${\mathfrak c}=2^{\aleph_0}$ (where $\mathfrak c$ is
the cardinality of the continuum); $S_{(q)}$ is a realization of the
permutation group on $\{0,1,2...\}$ as homeomorphisms of $\Zp$ stabilizing both
the nonpositive and nonnegative integers. We present a number of distinct
instances in which $S_{(q)}$ acts (or appears to act) as symmetries of our
functions. In particular, we present a natural, but highly mysterious, action
of $S_{(q)}$ on a large subset of the domain of our functions that appears to
stabilize zeta-zeroes. As of this writing, we do not yet know an overarching
formalism that unifies these examples; however, it would seem that this
formalism will involve an interplay between the 1-unit group $U_1$ -- playing
the role of a "gauge group" -- and $S_{(q)}$. Furthermore, we show that
$S_{(q)}$ may be naturally realized as an automorphism group of the convolution
algebras of characteristic $p$ valued measures.


title: Photoassociation spectroscopy of a Spin-1 Bose-Einstein condensate

abstract:
  We report on the high resolution photoassociation spectroscopy of a $^{87}$Rb
spin-1 Bose-Einstein condensate to the $1_\mathrm{g} (P_{3/2}) v = 152$ excited
molecular states. We demonstrate the use of spin dependent photoassociation to
experimentally identify the molecular states and their corresponding initial
scattering channel. These identifications are in excellent agreement with the
eigenvalues of a hyperfine-rotational Hamiltonian. Using the observed spectra
we estimate the change in scattering length and identify photoassociation laser
light frequency ranges that maximize the change in the spin-dependent
mean-field interaction energy.


title:
Direct photon production from hadronic sources in high-energy heavy-ion
  collisions

abstract:
  The low $p_T$ direct photon production from a variety of the hadronic sources
is studied within the microscopic HSD transport approach for p+C, p+Pb and
Pb+Pb collisions at 160 A GeV. The direct photon emission from elementary
hadronic scatterings as well as meson-meson bremsstrahlung are incorporated.
The influence of in-medium effects such as a collisional broadening of the
vector-meson spectral functions on the photon emission rate is found to be
hardly observable in the final spectra which are dominated by bremsstrahlung
type processes. The uncertainties in the subtraction of the 'background' from
the photon decay of hadronic resonances inside the hot and dense fireball is
investigated, additionally. Our findings are relevant for the interpretation
and extraction of experimental data on direct photon production at low $p_T$.


title: Dark dynamic acousto-optic ring lattices for ultracold atoms

abstract:
  We demonstrate the optical generation of dynamic dark optical ring lattices,
which do not require Laguerre-Gauss beams, large optical coherence lengths or
interferometric stability. Simple control signals lead to spatial modulation
and reproducible rotation, offering manifold possibilities for complex dynamic
ring lattices. In conjunction with a magnetic trap, these scanned 2D intensity
distributions from a single laser beam will enable precision trapping and
manipulation of ultracold species using blue-detuned light. The technique is
ideal for azimuthal ratchet, Mott insulator and persistent current experiments
with quantum degenerate gases.


title: Masses, fermions and generalized D-dimensional unitarity

abstract:
  We extend the generalized D-dimensional unitarity method for numerical
evaluation of one-loop amplitudes by incorporating massive particles. The
issues related to extending the spinor algebra to higher dimensions, treatment
of external self-energy diagrams and mass renormalization are discussed within
the context of the D-dimensional unitarity method. To validate our approach, we
calculate in QCD the one-loop scattering amplitudes of a massive quark pair
with up to three additional gluons for arbitrary spin states of the external
quarks and gluons.


title:
The role of binomial type sequences in determination identities for Bell
  polynomials

abstract:
  Our paper deals about identities involving Bell polynomials. Some identities
on Bell polynomials derived using generating function and successive
derivatives of binomial type sequences. We give some relations between Bell
polynomials and binomial type sequences in first part, and, we generalize the
results obtained in [4] in second part.


title:
Rationality, irrationality, and Wilf equivalence in generalized factor
  order

abstract:
  Let $P$ be a partially ordered set and consider the free monoid $P^*$ of all
words over $P$. If $w,w'\in P^*$ then $w'$ is a factor of $w$ if there are
words $u,v$ with $w=uw'v$. Define generalized factor order on $P^*$ by letting
$u\le w$ if there is a factor $w'$ of $w$ having the same length as $u$ such
that $u\le w'$, where the comparison of $u$ and $w'$ is done componentwise
using the partial order in $P$. One obtains ordinary factor order by insisting
that $u=w'$ or, equivalently, by taking $P$ to be an antichain.
  Given $u\in P^*$, we prove that the language $\cF(u)=\{w : w\ge u\}$ is
accepted by a finite state automaton. If $P$ is finite then it follows that the
generating function $F(u)=\sum_{w\ge u} w$ is rational. This is an analogue of
a theorem of Bj\"orner and Sagan for generalized subword order.
  We also consider $P=\bbP$, the positive integers with the usual total order,
so that $P^*$ is the set of compositions. In this case one obtains a weight
generating function $F(u;t,x)$ by substituting $tx^n$ each time $n\in\bbP$
appears in $F(u)$. We show that this generating function is also rational by
using the transfer-matrix method. Words $u,v$ are said to be Wilf equivalent if
$F(u;t,x)=F(v;t,x)$ and we prove various Wilf equivalences combinatorially.
  Bj\"orner found a recursive formula for the M\"obius function of ordinary
factor order on $P^*$. It follows that one always has $\mu(u,w)=0,\pm1$. Using
the Pumping Lemma we show that the generating function $M(u)=\sum_{w\ge u}
|\mu(u,w)| w$ can be irrational.


title: Galaxies Correlating with Ultra-high Energy Cosmic Rays

abstract:
  The Pierre Auger Observatory reports that 20 of the 27 highest energy cosmic
rays have arrival directions within 3.2 deg of a nearby galaxy in the
Veron-Cetty & Veron Catalog of Quasars and Active Galactic Nuclei (12th Ed.),
with ~5 of the correlations expected by chance. In this paper we examine the
correlated galaxies to gain insight into the possible UHECR sources. We find
that 14 of the 21 correlated VCV galaxies are AGNs and we determine their
bolometric luminosities. The remaining 7 are primarily star-forming galaxies.
The bolometric luminosities of the correlated AGNs are all greater than 5 x
10^{42} erg/s, which may explain the absence of UHECRs from the Virgo region in
spite of the large number of VCV galaxies in Virgo, since most of the VCV
galaxies in the Virgo region are low luminosity AGNs. Interestingly, the
bolometric luminosities of most of the AGNs are significantly lower than
required to satisfy the minimum condition for UHECR acceleration in a
continuous jet. If a UHECR-AGN correlation is substantiated with further
statistics, our results lend support to the recently proposed ``giant AGN
flare" mechanism for UHECR acceleration.


title: Stabilizing Tiny Interaction Protocols

abstract:
  In this paper we present the self-stabilizing implementation of a class of
token based algorithms. In the current work we only consider interactions
between weak nodes. They are uniform, they do not have unique identifiers, are
static and their interactions are restricted to a subset of nodes called
neighbours. While interacting, a pair of neighbouring nodes may create mobile
agents (that materialize in the current work the token abstraction) that
perform traversals of the network and accelerate the system stabilization. In
this work we only explore the power of oblivious stateless agents.
  Our work shows that the agent paradigm is an elegant distributed tool for
achieving self-stabilization in Tiny Interaction Protocols (TIP). Nevertheless,
in order to reach the full power of classical self-stabilizing algorithms more
complex classes of agents have to be considered (e.g. agents with memory,
identifiers or communication skills). Interestingly, our work proposes for the
first time a model that unifies the recent studies in mobile robots(agents)
that evolve in a discrete space and the already established population
protocols paradigm.


title:
Highest weight categories arising from Khovanov's diagram algebra II:
  Koszulity

abstract:
  This is the second of a series of four articles studying various
generalisations of Khovanov's diagram algebra. In this article we develop the
general theory of Khovanov's diagrammatically defined "projective functors" in
our setting. As an application, we give a direct proof of the fact that the
quasi-hereditary covers of generalised Khovanov algebras are Koszul.


title: A Spectroscopic Orbit for Regulus

abstract:
  We present a radial velocity study of the rapidly rotating B-star Regulus
that indicates the star is a single-lined spectroscopic binary. The orbital
period (40.11 d) and probable semimajor axis (0.35 AU) are large enough that
the system is not interacting at present. However, the mass function suggests
that the secondary has a low mass (M_2 > 0.30 M_sun), and we argue that the
companion may be a white dwarf. Such a star would be the remnant of a former
mass donor that was the source of the large spin angular momentum of Regulus
itself.


title:
Information field theory for cosmological perturbation reconstruction
  and non-linear signal analysis

abstract:
  We develop information field theory (IFT) as a means of Bayesian inference on
spatially distributed signals, the information fields. A didactical approach is
attempted. Starting from general considerations on the nature of measurements,
signals, noise, and their relation to a physical reality, we derive the
information Hamiltonian, the source field, propagator, and interaction terms.
Free IFT reproduces the well known Wiener-filter theory. Interacting IFT can be
diagrammatically expanded, for which we provide the Feynman rules in position-,
Fourier-, and spherical harmonics space, and the Boltzmann-Shannon information
measure. The theory should be applicable in many fields. However, here, two
cosmological signal recovery problems are discussed in their IFT-formulation.
1) Reconstruction of the cosmic large-scale structure matter distribution from
discrete galaxy counts in incomplete galaxy surveys within a simple model of
galaxy formation. We show that a Gaussian signal, which should resemble the
initial density perturbations of the Universe, observed with a strongly
non-linear, incomplete and Poissonian-noise affected response, as the processes
of structure and galaxy formation and observations provide, can be
reconstructed thanks to the virtue of a response-renormalization flow equation.
2) We design a filter to detect local non-linearities in the cosmic microwave
background, which are predicted from some Early-Universe inflationary
scenarios, and expected due to measurement imperfections. This filter is the
optimal Bayes' estimator up to linear order in the non-linearity parameter and
can be used even to construct sky maps of non-linearities in the data.

categories: astro-ph cs.IT hep-th math.IT physics.data-an stat.CO


title:
Rabi model beyond the rotating wave approximation: generation of photons
  from vacuum through decoherence

abstract:
  We study numerically the dynamics of the Rabi Hamiltonian, describing the
interaction of a single cavity mode and a two-level atom without the rotating
wave approximation, subjected to damping and dephasing reservoirs included via
usual Lindblad superoperators in the master equation. We show that the
combination of the antirotating term and the atomic dephasing leads to linear
asymptotic photons generation from vacuum. We reveal the origins of the
phenomenon and estimate its importance in realistic situations.


title: Suppressed fluctuations..

abstract:
  Suppression of fluctuations of normally perturbed magnetic fields in dynamo
waves and slow dynamos along curved (folded), torsioned (twisted) and
non-stretched, diffusive filaments are obtained. This form of fluctuations
suppression has been recently obtained by Vainshtein et al [PRE 56, (1997)] in
nonlinear ABC and stretch-twist-fold (STF) dynamos by using a magnetic Reynolds
number of the order of $Rm\approx{10^{4}}$. Here when torsion does not vanish
an expression between magnetic Reynolds number and length scale L as with
constant torsion ${\tau}_{0}$ itself is obtained, such as
$Rm\approx{\frac{{\tau}_{0}L}{\eta}}$ is obtained. At coronal loops
$Rm\approx{10^{12}}$ and torsion of the twisted structured loop from
astronomical data by Lopez-Fuentes et al [Astron. and Astrophys. (2003)] of
${\tau}\approx{9.0{\times}10^{-10}}cm^{-1}$ is used to compute a very slow
magnetic diffusion of ${\eta}\approx{10^{-8}}$. The slow dynamo obtained here
is in agreement with Vishik arguement that fast dynamo cannot be obtained in
non-stretched dynamo flows. When torsion vanishes helical turbulence is
quenched and but ${\alpha}$-dynamos cannot be maintained since exponential
stretching depends on torsion. This is actually Zeldovich antidynamo theorem
for torsion-free or planar filaments which has been discussed by the other also
recently in another context [Astr Nach. (2008)]. The suppression of magnetic
field fluctuations is actually a result of the coupling of the magnetic
diffusion and Frenet torsion of helical turbulence.


title:
Deflated and restarted symmetric Lanczos methods for eigenvalues and
  linear equations with multiple right-hand sides

abstract:
  A deflated restarted Lanczos algorithm is given for both solving symmetric
linear equations and computing eigenvalues and eigenvectors. The restarting
limits the storage so that finding eigenvectors is practical. Meanwhile, the
deflating from the presence of the eigenvectors allows the linear equations to
generally have good convergence in spite of the restarting. Some
reorthogonalization is necessary to control roundoff error, and several
approaches are discussed. The eigenvectors generated while solving the linear
equations can be used to help solve systems with multiple right-hand sides.
Experiments are given with large matrices from quantum chromodynamics that have
many right-hand sides.


title: Medium-mass nuclei from chiral nucleon-nucleon interactions

abstract:
  We compute the binding energies, radii, and densities for selected
medium-mass nuclei within coupled-cluster theory and employ the "bare" chiral
nucleon-nucleon interaction at order N3LO. We find rather well-converged
results in model spaces consisting of 15 oscillator shells, and the doubly
magic nuclei 40Ca, 48Ca, and the exotic 48Ni are underbound by about 1 MeV per
nucleon within the CCSD approximation. The binding-energy difference between
the mirror nuclei 48Ca and 48Ni is close to theoretical mass table evaluations.
Our computation of the one-body density matrices and the corresponding natural
orbitals and occupation numbers provides a first step to a microscopic
foundation of the nuclear shell model.


title: Comment of Global dynamics of biological systems

abstract:
  In a recent study, (Grigorov, 2006) analyzed temporal gene expression
profiles (Arbeitman et al., 2002) generated in a Drosophila experiment using
SSA in conjunction with Monte-Carlo SSA. The author (Grigorov, 2006) makes
three important claims in his article, namely:
  Claim1: A new method based on the theory of nonlinear time series analysis is
used to capture the global dynamics of the fruit-fly cycle temporal gene
expression profiles.
  Claim 2: Flattening of a significant part of the eigen-spectrum confirms the
hypothesis about an underly-ing high-dimensional chaotic generating process.
  Claim 3: Monte-Carlo SSA can be used to establish whether a given time series
is distinguishable from any well-defined process including deterministic chaos.
  In this report we present fundamental concerns with respect to the above
claims (Grigorov, 2006) in a systematic manner with simple examples. The
discussion provided especially discourages the choice of SSA for inferring
nonlinear dynamical structure form time series obtained in any biological
paradigm.


title: "Minesweeper" and spectrum of discrete Laplacians

abstract:
  The paper is devoted to a problem inspired by the "Minesweeper" computer
game. It is shown that certain configurations of open cells guarantee the
existence and the uniqueness of solution. Mathematically the problem is reduced
to some spectral properties of discrete differential operators. It is shown how
the uniqueness can be used to create a new game which preserves the spirit of
"Minesweeper" but does not require a computer.


title: The ancient Greeks present: Rational Trigonometry

abstract:
  Pythagoras' theorem, the area of a triangle as one half the base times the
height, and Heron's formula are amongst the most important and useful results
of ancient Greek geometry. Here we look at all three in a new and improved
light, using quadrance not distance. This leads to a simpler and more elegant
trigonometry, in which angle is replaced by spread, and which extends to
arbitrary fields and more general quadratic forms.


title: Shell revealed in SN 1979C

abstract:
  VLBI observations at 5 GHz have revealed that supernova 1979C, in the galaxy
M100 in the Virgo cluster, has shell structure. The shell is approximately
circular with the 50% contour deviating from a circle by an rms of no more than
8% of the radius. The brightness distribution along the ridge may vary. The
position of the center of the shell is at R.A.=12h 22m 58.66758s and decl.=15^o
47' 51.9695" (J2000), with a standard error of 0.8 mas in each of the
coordinates. No isolated central component is visible above a flux density
limit of ~0.15 mJy which corresponds to an upper limit of ~15 times the
corresponding spectral luminosity of the Crab Nebula. The radio lightcurve is
clearly falling again and the radio spectrum is now flatter than at earlier
times. SN 1979C is only the fourth, and oldest (optically identified) supernova
of which a detailed image could be obtained.


title: Cryptography in a Quantum World

abstract:
  Quantum computing had a profound impact on cryptography. Shor's discovery of
an efficient quantum algorithm for factoring large integers implies that many
existing classical systems based on computational assumptions can be broken,
once a quantum computer is built. It is therefore imperative to find other
means of implementing secure protocols. This thesis aims to contribute to the
understanding of both the physical limitations, as well as the possibilities of
cryptography in the quantum setting. In particular, we investigate several
questions that are crucial to the security of quantum protocols: How can we
find good uncertainty relations for a large number of measurement settings? How
does the presence of entanglement affect classical protocols? And, what
limitations does entanglement impose on implementing quantum protocols?
Finally, can we circumvent some of those limitations using realistic
assumptions?


title: Link invariants, the chromatic polynomial and the Potts model

abstract:
  We study the connections between link invariants, the chromatic polynomial,
geometric representations of models of statistical mechanics, and their common
underlying algebraic structure. We establish a relation between several
algebras and their associated combinatorial and topological quantities. In
particular, we define the chromatic algebra, whose Markov trace is the
chromatic polynomial \chi_Q of an associated graph, and we give applications of
this new algebraic approach to the combinatorial properties of the chromatic
polynomial. In statistical mechanics, this algebra occurs in the low
temperature expansion of the Q-state Potts model. We establish a relationship
between the chromatic algebra and the SO(3) Birman-Murakami-Wenzl algebra,
which is an algebra-level analogue of the correspondence between the SO(3)
Kauffman polynomial and the chromatic polynomial.

categories: math.CO cond-mat.stat-mech math.GT math.QA


title: Strong correlation effects in diatomic molecular electronic devices

abstract:
  We present a qualitative model for a fundamental process in molecular
electronics: the change in conductance upon bond breaking. In our model a
diatomic molecule is attached to spin-polarized contacts. Employing a Hubbard
Hamiltonian, electron interaction is neglected in the contacts and explicitly
considered in the molecule, enabling us to study the impact of electron
interaction on the molecular conductance. In the limit where the electron
repulsion is strong compared to the binding energy (as it becomes the case upon
dissociation) electron transmission in strongly suppressed compared to the
non-interacting case. However, the spin-polarized nature of the contacts
introduces a coupling between the molecular singlet and triplet states. This
coupling in turn yields additional resonances in the transmission probability
that significantly reduce the energetic separation appear between resonances.
The ramifications of our results on transport experiments performed on
nanowires with inclusions $H_2$ are discussed.


title:
Magnetic field-induced transition in a quantum magnet described by the
  Quantum Dimer Model

abstract:
  The effect of a magnetic field on a gapped quantum magnet is described within
the framework of the Quantum Dimer Model. A minimal model describing the
proliferation of itinerant spinons above a critical field is proposed and
investigated by Lanczos exact diagonalizations and quantum Monte Carlo
simulations. For both square and triangular lattices, it is shown that spinons
are fully polarized and Bose-condense. This offers a novel scenario of a
Quantum Critical Point in the dimer-liquid phase (triangular lattice)
characterized by the continuous appearance of a spinon superfluid density,
contrasting with the usual triplet condensation picture. The possible role of
other spinon kinetic terms neglected in the model are discussed.


title: The twisted Floer homology of torus bundles

abstract:
  Given a torus bundle $Y$ over the circle and a cohomology class $[\omega]\in
H^2(Y;\mathbb{Z})$ which evaluates nontrivially on the fiber, we compute the
Heegaard Floer homology of $Y$ with twisted coefficients in the universal
Novikov ring.


title: Many-Body Approximations in the sd-Shell Sandbox

abstract:
  A new theoretical approach is presented that combines the Hartree-Fock
variational scheme with the exact solution of the pairing problem in the finite
orbital space. Using this formulation in the sd-space as an example, we show
that the exact pairing significantly improves the results for the ground state
energy


title: Line-Defect Patterns of Unstable Spiral Waves in Cardiac Tissue

abstract:
  Spiral wave propagation in period-2 excitable media is often accompanied by
line-defects, the locus of points with period-1 oscillations. Here we
investigate spiral line-defects in cardiac tissue where period-2 behavior has a
known arrhythmogenic role. We find that the number of line defects, which is
constrained to be an odd integer, is three for a freely rotating spiral, with
and without meander, but one for a spiral anchored around a fixed
heterogeneity. We interpret analytically this finding using a simple theory
where spiral wave unstable modes with different numbers of line-defects
correspond to quantized solutions of a Helmholtz equation. Furthermore, the
slow inward rotation of spiral line-defects is described in different regimes.


title: Controlled quantum stirring of Bose-Einstein condensates

abstract:
  By cyclic adiabatic change of two control parameters of an optical trap one
can induce a circulating current of condensed bosons. The amount of particles
that are transported per period depends on the "radius" of the cycle, and this
dependence can be utilized in order to probe the interatomic interactions. For
strong repulsive interaction the current can be regarded as arising from a
sequence of Landau-Zener crossings. For weaker interaction one observes either
gradual or coherent mega crossings, while for attractive interaction the
particles are glued together and behave like a classical ball. For the analysis
we use the Kubo approach to quantum pumping with the associated Dirac monopoles
picture of parameter space.


title:
Chandra detection of XTE J1650-500 in quiescence and the minimum
  luminosity of black hole X-ray binaries

abstract:
  The Galactic black hole X-ray binary XTE J1650-500 entered a quiescent regime
following the decline from the 2001-2002 outburst that led to its discovery.
Here we report on the first detection of its quiescent counterpart in a 36 ks
observation taken in 2007 July with the Chandra X-ray Observatory. The inferred
0.5-10 keV unabsorbed flux is in the range 2.5-5.0x1e-15 erg/s/cm^2.
Notwithstanding large distance uncertainties, the measured luminosity is
comparable to that of the faintest detected black hole X-ray binaries, all
having orbital periods close to the expected bifurcation period between j- and
n-driven low-mass X-ray binaries. This suggests that a few 1e30 erg/s might be
a limiting luminosity value for quiescent black holes.


title: Cooper pairing reexamined

abstract:
  When both two-electron \textit{and} two-hole Cooper-pairing are treated on an
equal footing in the ladder approximation to the Bethe-Salpeter (BS) equation,
the zero-total-momentum Cooper-pair energy is found to have two \textit{real}
solutions $\mathcal{E}_{0}^{BS}=\pm 2\hbar \omega_{{D}%}/\sqrt{{e}^{2/\lambda
}+{1}}$ which coincide with the zero-temperature BCS energy gap $\Delta =\hbar
\omega_{D}/\sinh (1/\lambda) $ in the weak coupling limit. Here, $\hbar
\omega_{D}$ is the Debye energy and $\lambda \geq 0$ the BCS model interaction
coupling parameter. The interpretation of the BCS energy gap as the binding
energy of a Cooper-pair is often claimed in the literature but, to our
knowledge, never substantiated even in weak-coupling as we find here. In
addition, we confirm the two purely-\textit{imaginary} solutions assumed since
at least the late 1950s as the \textit{only} solutions, namely,
$\mathcal{E}_{0}^{BS}=\pm i2\hbar \omega_{{D}}/\sqrt{{e}^{2/\lambda}{-1}}.$


title:
Slowest relaxation mode of the partially asymmetric exclusion process
  with open boundaries

abstract:
  We analyze the Bethe ansatz equations describing the complete spectrum of the
transition matrix of the partially asymmetric exclusion process on a finite
lattice and with the most general open boundary conditions. We extend results
obtained recently for totally asymmetric diffusion [J. de Gier and F.H.L.
Essler, J. Stat. Mech. P12011 (2006)] to the case of partial symmetry. We
determine the finite-size scaling of the spectral gap, which characterizes the
approach to stationarity at large times, in the low and high density regimes
and on the coexistence line. We observe boundary induced crossovers and discuss
possible interpretations of our results in terms of effective domain wall
theories.


title:
A Super-high Angular Resolution Principle for Coded-mask X-ray Imaging
  Beyond the Diffraction Limit of Single Pinhole

abstract:
  High angular resolution X-ray imaging is always demanded by astrophysics and
solar physics, which can be realized by coded-mask imaging with very long
mask-detector distance in principle. Previously the diffraction-interference
effect has been thought to degrade coded-mask imaging performance dramatically
at low energy end with very long mask-detector distance. In this work the
diffraction-interference effect is described with numerical calculations, and
the diffraction-interference cross correlation reconstruction method (DICC) is
developed in order to overcome the imaging performance degradation. Based on
the DICC, a super-high angular resolution principle (SHARP) for coded-mask
X-ray imaging is proposed. The feasibility of coded mask imaging beyond the
diffraction limit of single pinhole is demonstrated with simulations. With the
specification that the mask element size of 50* 50 square micrometers and the
mask-detector distance of 50 m, the achieved angular resolution is 0.32 arcsec
above about 10 keV, and 0.36 arcsec at 1.24 keV where diffraction can not be
neglected. The on-axis source location accuracy is better than 0.02 arcsec.
Potential applications for solar observations and wide-field X-ray monitors are
also shortly discussed.


title:
Quantum theory of chemical reactions in the presence of electromagnetic
  fields

abstract:
  We present a theory for rigorous quantum scattering calculations of
probabilities for chemical reactions of atoms with diatomic molecules in the
presence of an external electric field. The approach is based on the fully
uncoupled basis set representation of the total wave function in the
space-fixed coordinate frame, the Fock-Delves hyperspherical coordinates and
adiabatic partitioning of the total Hamiltonian of the reactive system. The
adiabatic channel wave functions are expanded in basis sets of hyperangular
functions corresponding to different reaction arrangements and the interactions
with external fields are included in each chemical arrangement separately. We
apply the theory to examine the effects of electric fields on the chemical
reactions of LiF molecules with H atoms and HF molecules with Li atoms at low
temperatures and show that electric fields may enhance the probability of
chemical reactions and modify reactive scattering resonances by coupling the
rotational states of the reactants. Our preliminary results suggest that
chemical reactions of polar molecules at temperatures below 1 K can be
selectively manipulated with dc electric fields and microwave laser radiation.


title: On Modified Dispersion Relations and the Chandrasekhar Mass Limit

abstract:
  Modified dispersion relations from effective field theory are shown to alter
the Chandrasekhar mass limit. At exceptionally high densities, the
modifications affect the pressure of a degenerate electron gas and can increase
or decrease the mass limit, depending on the sign of the modifications. These
changes to the mass limit are unlikely to be relevant for the astrophysics of
white dwarf or neutron stars due to well-known dynamical instabilities that
occur at lower densities. Generalizations to frameworks other than effective
field theory are discussed.


title: Cosmic Inhomogeneities and the Average Cosmological Dynamics

abstract:
  If general relativity (GR) describes the expansion of the Universe, the
observed cosmic acceleration implies the existence of a `dark energy'. However,
while the Universe is on average homogeneous on large scales, it is
inhomogeneous on smaller scales. While GR governs the dynamics of the
\emph{in}homogeneous Universe, the averaged \emph{homogeneous} Universe obeys
modified Einstein equations. Can such modifications alone explain the
acceleration? For a simple generic model with realistic initial conditions, we
show the answer to be `no'. Averaging effects negligibly influence the
cosmological dynamics.


title:
Scaling limit of N=6 superconformal Chern-Simons theories and Lorentzian
  Bagger-Lambert theories

abstract:
  We show that the N=8 superconformal Bagger-Lambert theory based on the
Lorentzian 3-algebra can be derived by taking a certain scaling limit of the
recently proposed N=6 superconformal U(N)xU(N) Chern-Simons-matter theories at
level (k, -k). The scaling limit (and Inonu-Wigner contraction) is to scale the
trace part of the bifundamental fields as X_0 -> \lambda^{-1} X_0 and an axial
combination of the two gauge fields as B_{\mu} -> \lambda B_\mu. Simultaneously
we scale the level as k -> \lambda^{-1} k and then take \lambda -> 0 limit.
Interestingly the same constraint equation \partial^2 X_0=0 is derived by
imposing finiteness of the action. In this scaling limit, M2-branes are located
far from the origin of C^4/Z_k compared to their fluctuations and Z_k
identification becomes a circle identification. Hence the scaled theory
describes N=8 supersymmetric theory of 2-branes with dynamical coupling. The
coupling constant is promoted to a space-time dependent SO(8) vector X_0^I and
we show that the scaled theory has a generalized conformal symmetry as well as
manifest SO(8) with the transformation of the background fields X_0^I.


title: Hedlund-Metrics and the Stable Norm

abstract:
  The real homology of a compact Riemannian manifold $M$ is naturally endowed
with the stable norm. The stable norm on $H_1(M,\mathbb{R})$ arises from the
Riemannian length functional by homogenization. It is difficult and interesting
to decide which norms on the finite-dimensional vector space
$H_1(M,\mathbb{R})$ are stable norms of a Riemannian metric on $M$. If the
dimension of $M$ is at least three, I. Babenko and F. Balacheff proved in
\cite{baba} that every polyhedral norm ball in $H_1(M,\mathbb{R})$, whose
vertices are rational with respect to the lattice of integer classes in
$H_1(M,\mathbb{R})$, is the stable norm ball of a Riemannian metric on $M$.
This metric can even be chosen to be conformally equivalent to any given
metric. The proof in \cite{baba} uses singular Riemannian metrics on polyhedra
which are finally smoothed. Here we present an alternative construction of such
metrics which remains in the geometric framework of smooth Riemannian metrics.


title: White-noise-aided Control

abstract:
  The issue of white-noise-aided control is considered and its availability is
proved. And a noise-aiding way is developed to stabilize perturbed systems to
be input-to-state stable (ISS) with respect to (w.r.t.) perturbations. To
illustrate its effectiveness, the white-noise-aided control of a parameter
perturbed chaotic Chen system is given as an example. And numerically, it shows
that, comparing to the un-noise-aided case, noise-aided control can not only
shorten the control's transient process but also save its cost. These are also
demonstrated by various aiding noises such as common (symmetric) noise and
non-common (independent or asymmetric) noise, where common noise is found to be
the most efficient in enhancing the control.


title: Isotope shift calculations in Ti II

abstract:
  We present an accurate ab initio method of calculating transition energies
and isotope shifts in the 3d-transition metals. It extends previous work that
combines the configuration-interaction calculation with many-body perturbation
theory by including the effective three-body interaction and modification of
the energy denominator. We show that these effects are of importance in Ti II.
The need to develop methods that can accurately calculate isotope shifts in
3d-transition metals comes from studies of quasar absorption spectra that seek
to measure possible variation of the fine-structure constant alpha over the
lifetime of the Universe. Isotope shift can also be used to measure isotope
abundances in gas clouds in the early Universe, which are needed in order to
test models of chemical evolution.


title:
Spin-resolved impurity resonance states in electron-doped cuprate
  superconductors

abstract:
  With the aim at understanding the non-monotonic $d_{x^{2}-y^{2}}$-wave gap,
we analyze the local electronic structure near impurities in the electron-doped
cuprate superconductors. We find that the local density of states near a
non-magnetic impurity in the scenario of $d_{x^{2}-y^{2}}$-wave
superconductivity with higher harmonics is qualitatively different from that
obtained from the $d_{x^{2}-y^{2}}$-wave superconductivity coexisting with
antiferromagnetic spin density wave order. We propose that spin-polarized
scanning tunneling microscopy measurements can distinguish the two scenarios
and shed light on the real physical origin of a non-monotonic
$d_{x^{2}-y^{2}}$-wave gap.


title: Unbounded representations of $q$-deformation of Cuntz algebra

abstract:
  We study a deformation of the Cuntz-Toeplitz $C^*$-algebra determined by the
relations $a_i^*a_i=1+q a_ia_i^*, a_i^*a_j=0$. We define well-behaved unbounded
*-representations of the *-algebra defined by relations above and classify all
such irreducible representations up to unitary equivalence.


title: Gravitational field of domain wall in Lyra geometry

abstract:
  In this paper, we study the domain wall with time dependent displacement
vectors based on Lyra geometry in normal gauge i.e. displacement vector $f^*_i
= [ \beta (t), 0,0,0]$. The field theoretic energy momentum tensor is
considered with zero pressure perpendicular to the wall. We find an exact
solutions of Einstein equation for a scalar field $\phi$ with a potential
$V(\phi)$ describing the gravitational field of a plane symmetric domain wall.
We have seen that the hyper surfaces parallel to the wall ($ z = constant $)
are three dimensional de-sitter spaces. It is also shown that the gravitational
field experienced by test particle is attractive.


title:
Quantum Equivalence of Massive Antisymmetric Tensor Field Models in
  Curved Space

abstract:
  We study the effective actions for massive rank-2 and rank-3 antisymmetric
tensor field models in curved space-time. These models are classically
equivalent to massive vector field and massive scalar field with minimal
coupling to gravity respectively. We prove that effective action for massive
rank-2 antisymmetric tensor field is exactly equal to one for massive vector
field and effective action for massive rank-3 antisymmetric tensor field is
exactly equal to one for massive scalar field. Prove is based on an identity
for mass-dependent zeta-functions associated with Laplacians acting on
$p$-forms.


title: Shaken, but not stirred - Potts model coupled to quantum gravity

abstract:
  We investigate the critical behaviour of both matter and geometry of the
three-state Potts model coupled to two-dimensional Lorentzian quantum gravity
in the framework of causal dynamical triangulations. Contrary to what general
arguments of the effects of disorder suggest, we find strong numerical evidence
that the critical exponents of the matter are not changed under the influence
of quantum fluctuations in the geometry, compared to their values on fixed,
regular lattices. This lends further support to previous findings that quantum
gravity models based on causal dynamical triangulations are in many ways better
behaved than their Euclidean counterparts.


title: Maxwell operator on q-Minkowski space and q-hyperboloid algebras

abstract:
  We introduce an analog of the Maxwell operator on a q-Minkowski space algebra
(treated as a particular case of the so-called Reflection Equation Algebra) and
on certain of its quotients. We treat the space of "quantum differential forms"
as a projective module in the spirit of the Serre-Swan approach. Also, we use
"braided tangent vector fields" which are q-analogs of Poisson vector fields
associated to the Lie bracket sl(2).


title: Gazeau-Klauder type coherent states for hypergeometric type operators

abstract:
  The hypergeometric type operators are shape invariant, and a factorization
into a product of first order differential operators can be explicitly
described in the general case. Some additional shape invariant operators
depending on several parameters are defined in a natural way by starting from
this general factorization. The mathematical properties of the eigenfunctions
and eigenvalues of the operators thus obtained depend on the values of the
involved parameters. We study the parameter dependence of orthogonality, square
integrability and of the monotony of eigenvalue sequence. The obtained results
allow us to define certain systems of Gazeau-Klauder coherent states and to
describe some of their properties. Our systematic study recovers a number of
well-known results in a natural unified way and also leads to new findings.


title: Tensor-entanglement renormalization group approach to 2D quantum systems

abstract:
  Traditional mean-field theory is a simple generic approach for understanding
various phases. But that approach only applies to symmetry breaking states with
short-range entanglement. In this paper, we describe a generic approach for
studying 2D quantum phases with long-range entanglement (such as topological
phases). Our approach is a variational method that uses tensor product states
(also known as projected entangled pair states) as trial wave functions. We use
a 2D real space RG algorithm to evaluate expectation values in these wave
functions. We demonstrate our algorithm by studying several simple 2D quantum
spin models.

categories: cond-mat.str-el cond-mat.dis-nn cond-mat.stat-mech quant-ph


title:
Automatic regularization by quantization in reducible representations of
  CCR: Point-form quantum optics with classical sources

abstract:
  Electromagnetic fields are quantized in manifestly covariant way by means of
a class of reducible representations of CCR. $A_a(x)$ transforms as a Hermitian
four-vector field in Minkowski four-position space (no change of gauge), but in
momentum space it splits into spin-1 massless photons (optics) and two massless
scalars (similar to dark matter). Unitary dynamics is given by point-form
interaction picture, with minimal-coupling Hamiltonian constructed from fields
that are free on the null-cone boundary of the Milne universe. SL(2,C)
transformations and dynamics are represented unitarily in positive-norm Hilbert
space describing $N$ four-dimensional oscillators. Vacuum is a Bose-Einstein
condensate of the $N$-oscillator gas. Both the form of $A_a(x)$ and its
transformation properties are determined by an analogue of the twistor
equation. The same equation guarantees that the subspace of vacuum states is,
as a whole, Poincar\'e invariant. The formalism is tested on quantum fields
produced by pointlike classical sources. Photon statistics is well defined even
for pointlike charges, with UV/IR regularizations occurring automatically as a
consequence of the formalism. The probabilities are not Poissonian but of a
R\'enyi type with $\alpha=1-1/N$. The average number of photons occurring in
Bremsstrahlung splits into two parts: The one due to acceleration, and the one
that remains nonzero even if motion is inertial. Classical Maxwell
electrodynamics is reconstructed from coherent-state averaged solutions of
Heisenberg equations. Static pointlike charges polarize vacuum and produce
effective charge densities and fields whose form is sensitive to both the
choice of representation of CCR and the corresponding vacuum state.


title:
STAR measurement of system size and incident energy dependence of pt
  correlations at RHIC

abstract:
  We present the results on measurement of event-by-event pt fluctuations and
correlations for Cu+Cu collisions at sqrt{sNN} = 62.4 and 200 GeV from STAR
experiment at RHIC. These results are compared with those from Au+Au collisions
at sqrt{sNN} = 62.4 and 200 GeV to study the system size dependence. We find
that the dynamical pt fluctuations are finite and decrease with increasing
collision centrality. The pt correlations are studied as a function of
collision centrality and are observed to decrease as we go from peripheral to
central collisions. The square root of pt correlations scaled by mean pt are
observed to be independent of beam energy as well as colliding ion size.


title: Towards isotropic negative magnetics in the visible range

abstract:
  The idea of isotropic resonant magnetism in the visible range of frequencies
known from precedent publications is developed having in mind achievements of
the modern chemistry. Plasmonic colloidal nanoparticles covering a silica core
form a cluster with resonant and isotropic magnetic response. Two approximate
models giving the qualitative mutual agreement are used to evaluate the
magnetic polarizability of the cluster. It is shown that the electrostatic
interaction of nanocolloids decreases the resonant frequency of an individual
complex magnetic scatterer (nanocluster) compared to the previously studied
variant of a planar circular nanocluster with same size. This means the
reduction of the optical size of nanoclusters that presumably allows one to
avoid strong spatial dispersion within the frequency range of the negative
permeability.


title: Thermodynamic Geometry and Extremal Black Holes in String Theory

abstract:
  We study a generalisation of thermodynamic geometry to degenerate quantum
ground states at zero temperatures exemplified by charged extremal black holes
in type II string theories. Several examples of extremal charged black holes
with non degenerate thermodynamic geometries and finite but non zero state
space scalar curvatures are established. These include black holes described by
D1-D5-P and D2-D6-NS5-P brane systems and also two charged small black holes in
Type II string theories. We also explore the modifications to the state space
geometry and the scalar curvature due to the higher derivative contributions
and string loop corrections as well as an exact entropy expression from quantum
information theory. Our construction describes state space geometries arising
out of a possible limiting thermodynamic characterisation of degenerate quantum
ground states at zero temperatures.


title:
Consistent Newton-Raphson vs. fixed-point for variational multiscale
  formulations for incompressible Navier-Stokes

abstract:
  The following paper compares a consistent Newton-Raphson and fixed-point
iteration based solution strategy for a variational multiscale finite element
formulation for incompressible Navier-Stokes. The main contributions of this
work include a consistent linearization of the Navier-Stokes equations, which
provides an avenue for advanced algorithms that require origins in a consistent
method. We also present a comparison between formulations that differ only in
their linearization, but maintain all other equivalences. Using the variational
multiscale concept, we construct a stabilized formulation (that may be
considered an extension of the MINI element to nonlinear Navier-Stokes). We
then linearize the problem using fixed-point iteration and by deriving a
consistent tangent matrix for the update equation to obtain the solution via
Newton-Raphson iterations. We show that the consistent formulation converges in
fewer iterations, as expected, for several test problems. We also show that the
consistent formulation converges for problems for which fixed-point iteration
diverges. We present the results of both methods for problems of Reynold's
number up to 5000.


title: Ternary Virasoro - Witt Algebra

abstract:
  A 3-bracket variant of the Virasoro-Witt algebra is constructed through the
use of su(1,1) enveloping algebra techniques. The Leibniz rules for 3-brackets
acting on other 3-brackets in the algebra are discussed and verified in various
situations.


title:
Eigenvalues of a nonlinear ground state in the Thomas-Fermi
  approximation

abstract:
  We study a nonlinear ground state of the Gross-Pitaevskii equation with a
parabolic potential in the hydrodynamics limit often referred to as the
Thomas--Fermi approximation. Existence of the energy minimizer has been known
in literature for some time but it was only recently when the Thomas-Fermi
approximation was rigorously justified. The spectrum of linearization of the
Gross-Pitaevskii equation at the ground state consists of an unbounded sequence
of positive eigenvalues. We analyze convergence of eigenvalues in the
hydrodynamics limit. Convergence in norm of the resolvent operator is proved
and the convergence rate is estimated. We also study asymptotic and numerical
approximations of eigenfunctions and eigenvalues using Airy functions.


title:
Spectral inversion of an indefinite Sturm-Liouville problem due to
  Richardson

abstract:
  We study an indefinite Sturm-Liouville problem due to Richardson whose
complicated eigenvalue dependence on a parameter has been a puzzle for decades.
In atomic physics a process exists that inverts the usual Schrodinger situation
of an energy eigenvalue depending on a coupling parameter into the so-called
Sturmian problem where the coupling parameter becomes the eigenvalue which then
depends on the energy. We observe that the Richardson equation is of the
Sturmian type. This means that the Richardson and its related Schrodinger
eigevalue functions are inverses of each other and that the Richardson spectrum
is therefore no longer a puzzle.


title: Restarting engine in an X-shaped radio galaxy

abstract:
  J2018-556, an X-shaped FR-I radio galaxy provides a unique opportunity to
discuss the formation scenarios for the extended structures seen in this class
of radio sources. An understanding of the origin of X-shaped source structures
has important implications for radio galaxy models as well as black hole-black
hole mergers. Guided by our ATCA radio continuum observations of J2018-556 we
discuss evidence in support of 'wings' forming as a result of a redirection of
backflows by asymmetric gas distribution associated with the host galaxy.
Formation models invoking interaction between backflows with asymmetric
environments seem the preferred model for X-shaped radio sources despite
apparent discoveries of X-shaped FR-I radio sources.


title:
Limiting Dynamics for Spherical Models of Spin Glasses with Magnetic
  Field

abstract:
  We study the Langevin dynamics for the family of spherical spin glass models
of statistical physics, in the presence of a magnetic field. We prove that in
the limit of system size N approaching infinity, the empirical state
correlation, the response function, the overlap and the magnetization for these
N-dimensional coupled diffusions converge to the non-random unique strong
solution of four explicit non-linear integro-differential equations, that
generalize the system proposed by Cugliandolo and Kurchan in the presence of a
magnetic field. We then analyze the system and provide a rigorous derivation of
the FDT regime in a large area of the temperature-magnetization plane.


title: On Nambu-Lie 3-algebra representations

abstract:
  We propose a recipe to construct matrix representations of Nambu--Lie
3-algebras in terms of irreducible representations of underlying Lie algebra.
The case of Euclidean four-dimensional 3-algebra is considered in details. We
find that representations of this 3-algebra are not possible in terms of only
Hermitian matrices in spite of its Euclidean nature.


title:
Laboratory performances of the solar multichannel resonant scattering
  spectrometer prototype of the GOLF-New Generation instrument

abstract:
  This article quickly summarizes the performances and results of the GOLF/SoHO
resonant spectrometer, thus justifying to go a step further. We then recall the
characteristics of the multichannel resonant GOLF-NG spectrometer and present
the first successful performances of the laboratory tests on the prototype and
also the limitations of this first technological instrument. Scientific
questions and an observation strategy are discussed.


title: Riemannian Geometry of Lie Algebroids

abstract:
  We introduce Riemannian Lie algebroids as a generalization of Riemannian
manifolds and we show that most of the classical tools and results known in
Riemannian geometry can be stated in this setting. We give also some new
results on the integrability of Riemannian Lie algebroids.


title: Forces in electromagnetic field and gravitational field

abstract:
  The force can be defined from the linear momentum in the gravitational field
and electromagnetic field. But this definition can not cover the gradient of
energy. In the paper, the force will be defined from the energy and torque in a
new way, which involves the gravitational force, electromagnetic force,
inertial force, gradient of energy, and some other new force terms etc. One of
these new force terms can be used to explain why the solar wind varies velocity
along the magnetic force line in the interplanetary space between the sun and
the earth.


title: Model of multiphoton transitions in a current-biased Josephson junction

abstract:
  We present a simple model for multiphoton transitions between the quasi-bound
states of a current-driven Josephson junction. The transitions are induced by
applying an ac voltage with controllable frequency and amplitude across the
junction. The voltage induces transitions when the ac frequency equals n times
the splitting between the ground and first excited quasi-bound state of the
junction. We calculate the transition matrix elements as functions of the dc
bias current I, and the frequency and amplitude of the ac voltage, for
representative junction parameters. We also calculate the frequency-dependent
absorption coefficient by solving the relevant Bloch equations when the ac
amplitude is sufficiently small. In this regime, the absorption coefficient is
a sum of Lorentzian lines centered at the n-photon absorption frequency, of
strength proportional to the squared matrix elements. For fixed ac voltage
amplitude, the n-photon transition rate usually decreases with increasing n. We
also find a characteristic even-odd effect: The absorption coefficient
typically increases with I for n even but decreases for n odd. Our results
agree qualitatively with recent experiments.


title:
Secret Keys Assisted Private Classical Communication Capacity over
  Quantum Channels

abstract:
  We prove a regularized formula for the secret key-assisted capacity region of
a quantum channel for transmitting private classical information. This result
parallels the work of Devetak on entanglement assisted quantum communication
capacity \cite{DHW05RI}. This formula provides a new family protocol, the
private father protocol, under the resource inequality framework that includes
private classical communication \it{without} secret key assistance as a child
protocol.


title:
Electronic structures of ternary iron arsenides AFe$_2$As$_2$ (A=Ba, Ca,
  or Sr)

abstract:
  We have studied the electronic and magnetic structures of the ternary iron
arsenides AFe$_2$As$_2$ (A = Ba, Ca, or Sr) using the first-principles density
functional theory. The ground states of these compounds are in a collinear
antiferromagnetic order, resulting from the interplay between the nearest and
the next-nearest neighbor superexchange antiferromagnetic interactions bridged
by As $4p$ orbitals. The correction from the spin-orbit interaction to the band
structure is small. The pressure can reduce dramatically the magnetic moment
and diminish the collinear antiferromagnetic order. Based on the calculations,
we propose that the low energy dynamics of these materials is described
effectively by a $t-J_H-J_1-J_2$-type model.


title: Search for third generation scalar leptoquarks decaying into tau b

abstract:
  We have searched for third generation leptoquarks (LQ3) using 1.05 inverse
femtobarns of data collected with the D0 detector at the Fermilab Tevatron
Collider operating at sqrt(s)=1.96 TeV. We set a 95% C.L. lower limit of 210
GeV on the mass of a scalar LQ3 state decaying solely to a b quark and a tau
lepton.


title:
Computer simulations of two-dimensional melting with dipole-dipole
  interactions

abstract:
  We perform molecular dynamics and Monte Carlo simulations of two-dimensional
melting with dipole-dipole interactions. Both static and dynamic behaviors are
examined. In the isotropic liquid phase, the bond orientational correlation
length 6 and susceptibility 6 are measured, and the data are fitted to the
theoretical ansatz. An algebraic decay is detected for both spatial and
temporal bond orientational correlation functions in an intermediate
temperature regime, and it provides an explicit evidence for the existence of
the hexatic phase. From the finite-size scaling analysis of the global bond
orientational order parameter, the disclination unbinding temperature Ti is
estimated. In addition, from dynamic Monte Carlo simulations of the positional
order parameter, we extract the critical exponents at the dislocation unbinding
temperature Tm. All the results are in agreement with those from experiments
and support the Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) theory.


title: Geometric phases and quantum phase transitions in open systems

abstract:
  The relationship between quantum phase transition and complex geometric phase
for open quantum system governed by the non-Hermitian effective Hamiltonian
with the accidental crossing of the eigenvalues is established. In particular,
the geometric phase associated with the ground state of the one-dimensional
dissipative Ising model in a transverse magnetic field is evaluated, and it is
demonstrated that related quantum phase transition is of the first order.


title:
First principles study of structural stability and electronic structure
  of CdS nanoclusters

abstract:
  Using first-principles density functional calculations, we have studied the
structural stability of stoichiometric as well as non-stoichiometric CdS
nanoclusters at ambient pressure with diameters ranging up to about 2.5 nm. Our
study reveals that the relative stability of the two available structures for
CdS, namely zinc blende and wurtzite, depends sensitively on the details like
surface geometry and/or surface chemistry. The associated band gap also
exhibits non-monotonic behavior as a function of cluster size. Our findings may
shed light on reports of experimentally observed structures and associated
electronic structures of CdS nanoclusters found in the literature.


title:
Matrix valued polynomials generated by the scalar-type Rodrigues'
  formulas

abstract:
  The properties of matrix valued polynomials generated by the scalar-type
Rodrigues' formulas are analyzed. A general representation of these polynomials
is found in terms of products of simple differential operators. The recurrence
relations, leading coefficients, completeness are established, as well as, in
the commutative case, the second order equations for which these polynomials
are eigenfunctions and the corresponding eigenvalues, and ladder operators.
  The conjecture of Duran and Grunbaum that if the weights are self-adjoint and
positive semidefinite then they are necessarily of scalar type is proved for
Q(x)=x and Q(x)=x^2-1 in dimension two, and for any dimension under genericity
assumptions.
  Commutative classes of quasi-orthogonal polynomials are found, which satisfy
all the properties usually associated to orthogonal polynomials.


title: The Titius-Bode Law Revisited But Not Revived

abstract:
  The present article gives a detailed analysis of the new formulation of
Titius-Bode law by (Poveda, Lara 2008) and of the hypothesis that this law may
exist in extra-solar planetary system. A thorough study of the correspondences
between the calculated distances and the observed ones in the Solar system and
in 55 Cancri is given. It is shown that Poveda-Lara hypothesis contains serious
mistakes (both in theory and in calculations) that makes it unacceptable.


title: The electronic phase diagram of the LaO1-xFxFeAs superconductor

abstract:
  The competition of magnetic order and superconductivity is a key element in
the physics of all unconventional superconductors, e.g. in
high-transition-temperature cuprates 1, heavy fermions 2 and organic
superconductors3. Here superconductivity is often found close to a quantum
critical point where long-range antiferromagnetic order is gradually suppressed
as a function of a control parameter, e.g. charge carrier doping or pressure.
It is believed that dynamic spin fluctuations associated with this quantum
critical behaviour are crucial for the mechanism of superconductivity. Recently
high-temperature superconductivity has been discovered in iron-pnictides
providing a new class of unconventional superconductors4,5,6. Similar to other
unconventional superconductors the parent compounds of the pnictides exhibit a
magnetic ground state7,8 and superconductivity is induced upon charge carrier
doping. In this Letter the structural and electronic phase diagram is
investigated by means of x-ray scattering, MuSR and Moessbauer spectroscopy on
the series LaO1-xFxFeAs. We find a discontinuous first-order-like change of the
Neel temperature, the superconducting transition temperature and of the
respective order parameters. Our results strongly question the relevance of
quantum critical behaviour in ironpnictides and prove a strong coupling of the
structural orthorhombic distortion and the magnetic order both disappearing at
the phase boundary to the superconducting state.


title: Metric Lie n-algebras and double extensions

abstract:
  We prove a structure theorem for Lie n-algebras possessing an invariant inner
product. We define the notion of a double extension of a metric Lie n-algebra
by another Lie n-algebra and prove that all metric Lie n-algebras are obtained
from the simple and one-dimensional ones by iterating the operations of
orthogonal direct sum and double extension.


title: Detailed Study of the KL -> 3pi0 Dalitz Plot

abstract:
  Using a sample of 68 million KL -> 3pi0 decays collected in 1996-1999 by the
KTeV (E832) experiment at Fermilab, we present a detailed study of the KL ->
3pi0 Dalitz plot density. We report the first observation of interference from
KL->pi+pi-pi0 decays in which pi+pi- rescatters to 2pi0 in a final-state
interaction. This rescattering effect is described by the Cabibbo-Isidori
model, and it depends on the difference in pion scattering lengths between the
isospin I=0 and I=2 states, a0-a2. Using the Cabibbo-Isidori model, we present
the first measurement of the KL-> 3pi0 quadratic slope parameter that accounts
for the rescattering effect.


title: In Pursuit of Spreadsheet Excellence

abstract:
  The first fully-documented study into the quantitative impact of errors in
operational spreadsheets identified an interesting anomaly. One of the five
participating organisations involved in the study contributed a set of five
spreadsheets of such quality that they set the organisation apart in a
statistical sense. This virtuoso performance gave rise to a simple sampling
test - The Clean Sheet Test - which can be used to objectively evaluate if an
organisation is in control of the spreadsheets it is using in important
processes such as financial reporting.


title: Statistical Learning of Arbitrary Computable Classifiers

abstract:
  Statistical learning theory chiefly studies restricted hypothesis classes,
particularly those with finite Vapnik-Chervonenkis (VC) dimension. The
fundamental quantity of interest is the sample complexity: the number of
samples required to learn to a specified level of accuracy. Here we consider
learning over the set of all computable labeling functions. Since the
VC-dimension is infinite and a priori (uniform) bounds on the number of samples
are impossible, we let the learning algorithm decide when it has seen
sufficient samples to have learned. We first show that learning in this setting
is indeed possible, and develop a learning algorithm. We then show, however,
that bounding sample complexity independently of the distribution is
impossible. Notably, this impossibility is entirely due to the requirement that
the learning algorithm be computable, and not due to the statistical nature of
the problem.


title:
Predicting future duration from present age: Revisiting a critical
  assessment of Gott's rule

abstract:
  Gott has promulgated a rule for making probabilistic predictions of the
future duration of a phenomenon based on the phenomenon's present age [Nature,
Vol. 363, 315 (1993)]. I show that the two usual methods for deriving Gott's
rule are flawed. Nothing licenses indiscriminate use of Gott's rule as a
predictor of future duration. It should only be used when the phenomenon in
question has no identifiable time scales.

categories: astro-ph gr-qc physics.data-an physics.pop-ph


title: Cohomology of GKM Fiber Bundles

abstract:
  The equivariant cohomology ring of a GKM manifold is isomorphic to the
cohomology ring of its GKM graph. In this paper we explore the implications of
this fact for equivariant fiber bundles for which the total space and the base
space are both GKM and derive a graph theoretical version of the Leray-Hirsch
theorem. Then we apply this result to the equivariant cohomology theory of flag
varieties.


title:
Three-Tone Intermodulation Distortion Generated by Superconducting
  Bandpass Filters

abstract:
  Microwave bandpass filters constructed from materials exhibiting some
nonlinearity, such as superconductors, will generate intermodulation distortion
(IMD) when subjected to signals at more than one frequency. In commercial
applications of superconductive receive filters, it is possible for IMD to be
generated when a weak receive signal mixes with very strong out-of-band
signals, such as those coming from the transmitter. A measurement procedure was
developed and data were taken on several different types of superconducting
bandpass filters, all developed for commercial application. It was found that
in certain interference situations, the 3-tone mixing can produce a spur that
is noticeable by the receiver, but that there are simple preventative design
solutions.


title:
The Dust Scattering Model Can Not Explain The Shallow X-ray Decay in GRB
  Afterglows

abstract:
  A dust scattering model was recently proposed to explain the shallow X-ray
decay (plateau) observed prevalently in Gamma-Ray Burst (GRB) early afterglows.
In this model the plateau is the scattered prompt X-ray emission by the dust
located close (about 10 to a few hundred pc) to the GRB site. In this paper we
carefully investigate the model and find that the scattered emission undergoes
strong spectral softening with time, due to the model's essential ingredient
that harder X-ray photons have smaller scattering angle thus arrive earlier,
while softer photons suffer larger angle scattering and arrive later. The model
predicts a significant change, i.e., $\Delta \b \sim 2 - 3$, in the X-ray
spectral index from the beginning of the plateau toward the end of the plateau,
while the observed data shows close to zero softening during the plateau and
the plateau-to-normal transition phase. The scattering model predicts a big
difference between the harder X-ray light curve and the softer X-ray light
curve, i.e., the plateau in harder X-rays ends much earlier than in softer
X-rays. This feature is not seen in the data. The large scattering optical
depths of the dust required by the model imply strong extinction in optical,
$A_V \gtrsim $ 10, which contradicts current findings of $A_V= 0.1 - 0.7$ from
optical and X-ray afterglow observations. We conclude that the dust scattering
model can not explain the X-ray plateaus.


title: Design and Analysis of an Asynchronous Zero Collision MAC Protocol

abstract:
  This paper proposes and analyzes a distributed MAC protocol that achieves
zero collision with no control message exchange nor synchronization. ZC
(ZeroCollision) is neither reservation-based nor dynamic TDMA; the protocol
supports variable-length packets and does not lose efficiency when some of the
stations do not transmit. At the same time, ZC is not a CSMA; in its steady
state, it is completely collision-free. The stations transmit repeatedly in a
round-robin order once the convergence state is reached. If some stations skip
their turn, their transmissions are replaced by idle $20 \mu$-second mini-slots
that enable the other stations to keep track of their order. Because of its
short medium access delay and its efficiency, the protocol supports both
real-time and elastic applications. The protocol allows for nodes leaving and
joining the network; it can allocate more throughput to specific nodes (such as
an access point). The protocol is robust against carrier sensing errors or
clock drift. While collision avoidance is guaranteed in a single collision
domain, it is not the case in a multiple collision one. However, experiments
show ZC supports a comparable amount of goodput to CSMA in a multiple collision
domain environment. The paper presents an analysis and extensive simulations of
the protocol, confirming that ZC outperforms both CSMA and TDMA at high and low
load.


title: Ghost imaging in scattering media

abstract:
  Ghost imaging with thermal light in scattering media is investigated. We
demonstrated both theoretically and experimentally for the first time that the
image with high quality can still be obtained in the scattering media by ghost
imaging. The scattering effect on the qualities of the images obtained when the
object is illuminated directly by the thermal light and ghost imaging is
analyzed theoretically. Its potential applications are also discussed.


title: The most massive core collapse supernova progenitors

abstract:
  The discovery of the extremely luminous supernova SN 2006gy, possibly
interpreted as a pair instability supernova, renewed the interest in very
massive stars. We explore the evolution of these objects, which end their life
as pair instability supernovae or as core collapse supernovae with relatively
massive iron cores, up to about $3 M_\odot$.


title: Relaxed optimality conditions for mu-differentiable functions

abstract:
  We prove some fundamental properties of mu-differentiable functions. A new
notion of local minimizer and maximizer is introduced and several extremum
conditions are formulated using the language of nonstandard analysis.


abstract:
  Let $p(z,w)$ be a polynomial in two variables. We call the solution of the
algebraic equation $p(z,w) = 0$ the algebraic correspondence. We regard it as
the graph of the multivalued function $z \mapsto w$ defined implicitly by
$p(z,w) = 0$. Algebraic correspondences on the Riemann sphere $\hat{\mathbb C}$
give a generalization of dynamical systems of Klein groups and rational
functions. We introduce $C^*$-algebras associated with algebraic
correspondences on the Riemann sphere. We show that if an algebraic
correspondence is free and expansive on a closed $p$-invariant subset $J$ of
$\hat{\mathbb C}$, then the associated $C^*$-algebra ${\mathcal O}_p(J)$ is
simple and purely infinite.


title: Uncollapsing of a quantum state in a superconducting phase qubit

abstract:
  We demonstrate in a superconducting qubit the conditional recovery
("uncollapsing") of a quantum state after a partial-collapse measurement. A
weak measurement extracts information and results in a non-unitary
transformation of the qubit state. However, by adding a rotation and a second
partial measurement with the same strength, we erase the extracted information,
effectively canceling the effect of both measurements. The fidelity of the
state recovery is measured using quantum process tomography and found to be
above 70% for partial-collapse strength less than 0.6.


title: D1-D3 (or $\bar{\textrm{D}3}$) Systems with Fluxes

abstract:
  In this article we study D1-D3 (or $\bar{\textrm{D}3}$) brane systems with
generic constant electric and magnetic fluxes in IIB string theory. We work out
all possible supersymmetric configurations and find out via T-duality all of
them and corresponding supersymmetry conditions could be related to the
supersymmetric intersecting D1-D1 pairs. And we do D1-D3 (or
$\bar{\textrm{D}3}$) open string quantization for a class of configurations. We
find that there are many near massless states in NS sector for near-BPS
configurations. Furthermore we calculate open string pair creation rate in
generic nonsupersymmetric configurations.