title:
Harmonic Stability Analysis of the 2D Square and Hexagonal Bravais
  Lattices for a Finite--Ranged Repulsive Pair Potential. Consequence for a 2D
  System of Ultracold Composite Bosons

abstract:
  We consider a classical, two-dimensional system of identical particles which
interact via a finite-ranged, repulsive pair potential. We assume that the
system is in a crystalline phase. We calculate the normal vibrational modes of
a two-dimensional square Bravais lattice, first analytically within the
nearest-neighbour approximation, and then numerically, relaxing the preceding
hypothesis. We show that, in the harmonic approximation, the excitation of a
transverse vibrational mode leads to the breakdown of the square lattice. We
next study the case of the hexagonal Bravais lattice and we show that it can be
stable with respect to lattice vibrations. We give a criterion determining
whether or not it is stable in the nearest-neighbour approximation. Finally, we
apply our results to a two-dimensional system of composite bosons and infer
that the crystalline phase of such a system, if it exists, corresponds to a
hexagonal lattice.


title: An Efficient Algorithm for 2D Euclidean 2-Center with Outliers

abstract:
  For a set P of n points in R^2, the Euclidean 2-center problem computes a
pair of congruent disks of the minimal radius that cover P. We extend this to
the (2,k)-center problem where we compute the minimal radius pair of congruent
disks to cover n-k points of P. We present a randomized algorithm with O(n k^7
log^3 n) expected running time for the (2,k)-center problem. We also study the
(p,k)-center problem in R}^2 under the \ell_\infty-metric. We give solutions
for p=4 in O(k^{O(1)} n log n) time and for p=5 in O(k^{O(1)} n log^5 n) time.


title:
Cosmological scalar fields that mimic the $\Lambda CDM$ cosmological
  model

abstract:
  We look for cosmologies with a scalar field (dark energy without cosmological
constant), which mimic the standard $\Lambda CDM$ cosmological model yielding
exactly the same large-scale geometry described by the evolution of the Hubble
parameter (i.e. photometric distance and angular diameter distance as functions
on $z$). Asymptotic behavior of the field solutions is studied in the case of
spatially flat Universe with pressureless matter and separable scalar field
Lagrangians (power-law kinetic term + power-law potential). Exact analytic
solutions are found in some special cases. A number of models have the field
solutions with infinite behavior in the past or even singular behavior at
finite redshifts. We point out that introduction of the cosmological scalar
field involves some degeneracy leading to lower precision in determination of
$\Omega_m$. To remove this degeneracy additional information is needed beyond
the data on large-scale geometry.


title: First order structural phase transition in CaFe$_2$As$_2$

abstract:
  CaFe$_2$As$_2$ has been synthesized and found to form in the tetragonal,
ThCr$_2$Si$_2$ structure with lattice parameters $a = 3.912(68) \AA$ and $c =
11.667(45) \AA$. Upon cooling through 170 K, CaFe$_2$As$_2$ undergoes a first
order, structural phase transition to a low temperature, orthorhombic phase
with a $2 - 3$ K range of hysteresis and coexistence. This transition is
clearly evident in microscopic, thermodynamic and transport measurements.
CaFe$_2$As$_2$ is the third member of the AFe$_2$As$_2$ (A = Ba, Sr, Ca) family
to exhibit such a dramatic phase transition and is a promising candidate for
studies of doping induced superconductivity.


title: Heat-flow monotonicity related to the Hausdorff--Young inequality

abstract:
  It is known that if $q$ is an even integer then the $L^q(\mathbb{R}^d)$ norm
of the Fourier transform of a superposition of translates of a fixed gaussian
is monotone increasing as their centres "simultaneously slide" to the origin.
We provide explicit examples to show that this monotonicity property fails
dramatically if $q > 2$ is not an even integer. These results are equivalent,
upon rescaling, to similar statements involving solutions to heat equations.
Such considerations are natural given the celebrated theorem of Beckner
concerning the gaussian extremisability of the Hausdorff--Young inequality.


title: Sums and Differences of Three k-th Powers

abstract:
  Let k>2 be a fixed integer exponent and let \theta > 9/10. We show that a
positive integer N can be represented as a non-trivial sum or difference of 3
k-th powers, using integers of size at most B, in O(B^{\theta}N^{1/10}) ways,
providing that N << B^{3/13}. The significance of this is that we may take
\theta strictly less than 1. We also prove the estimate O(B^{10/k}), (subject
to N << B) which is better for large k.
  The results extend to representations by an arbitrary fixed nonsingular
ternary from. However ``non-trivial'' must then be suitably defined.
Consideration of the singular form x^{k-1}y-z^k allows us to establish an
asymptotic formula for (k-1)-free values of p^k+c, when p runs over primes,
answering a problem raised by Hooley.


title:
A temperature-controlled device for volumetric measurements of Helium
  adsorption in porous media

abstract:
  We describe a set-up for studying adsorption of helium in silica aerogels,
where the adsorbed amount is easily and precisely controlled by varying the
temperature of a gas reservoir between 80 K and 180 K. We present validation
experiments and a first application to aerogels. This device is well adapted to
study hysteresis, relaxation, and metastable states in the adsorption and
desorption of fluids in porous media.


title: Superstatistical distributions from a maximum entropy principle

abstract:
  We deal with a generalized statistical description of nonequilibrium complex
systems based on least biased distributions given some prior information. A
maximum entropy principle is introduced that allows for the determination of
the distribution of the fluctuating intensive parameter $\beta$ of a
superstatistical system, given certain constraints on the complex system under
consideration. We apply the theory to three examples: The superstatistical
quantum mechanical harmonic oscillator, the superstatistical classical ideal
gas, and velocity time series as measured in a turbulent Taylor-Couette flow.


title: The Ratio Monotonicity of the Boros-Moll Polynomials

abstract:
  In their study of a quartic integral, Boros and Moll discovered a special
class of Jacobi polynomials, which we call the Boros-Moll polynomials. Kauers
and Paule proved the conjecture of Moll that these polynomials are log-concave.
In this paper, we show that the Boros-Moll polynomials possess the ratio
monotone property which implies the log-concavity and the spiral property. We
conclude with a conjecture which is stronger than Moll's conjecture on the
$\infty$-log-concavity.


title: QUIET - Measuring the CMB polarization with coherent detector arrays

abstract:
  The footprint of inflation in the polarization pattern of the CMB is expected
at more than an order of magnitude below the limits of current polarization
measurements. Large receiver arrays are mandatory for achieving the required
sensitivity. We describe here the approach of the Q/U Imaging ExperimenT
(QUIET) which will use coherent detector arrays. Pseudo-correlation receivers
have been produced at 40 (90) GHz in small massproducable chip packages.
Deployment of the first arrays with 19 (91) receivers is taking place in 2008
in the Atacama Desert in Chile and an expansion to $\sim$1000 receivers is
foreseen for the future. The two frequencies and the selection of observing
regions with minimal foreground and good overlap with other upcoming
experiments will enable the detection of tensor to scalar ratios
$r\sim10^{-2}$.


title:
Schroedingers equation with gauge coupling derived from a continuity
  equation

abstract:
  We consider a statistical ensemble of particles of mass m, which can be
described by a probability density \rho and a probability current \vec{j} of
the form \rho \nabla S/m. The continuity equation for \rho and \vec{j} implies
a first differential equation for the basic variables \rho and S. We further
assume that this system may be described by a linear differential equation for
a complex state variable \chi. Using this assumptions and the simplest possible
Ansatz \chi(\rho,S) Schroedingers equation for a particle of mass m in an
external potential V(q,t) is deduced. All calculations are performed for a
single spatial dimension (variable q) Using a second Ansatz \chi(\rho,S,q,t)
which allows for an explict q,t-dependence of \chi, one obtains a generalized
Schroedinger equation with an unusual external influence described by a
time-dependent Planck constant. All other modifications of Schroeodingers
equation obtained within this Ansatz may be eliminated by means of a gauge
transformation. Thus, this second Ansatz may be considered as a generalized
gauging procedure. Finally, making a third Ansatz, which allows for an
non-unique external q,t-dependence of \chi, one obtains Schroedingers equation
with electromagnetic potentials \vec{A}, \phi in the familiar gauge coupling
form. A possible source of the non-uniqueness is pointed out.


title: Electron counting with a two-particle emitter

abstract:
  We consider two driven cavities (capacitors) connected in series via an edge
state. The cavities are driven such that they emit an electron and a hole in
each cycle. Depending on the phase lag the second cavity can effectively absorb
the carriers emitted by the first cavity and nullify the total current or the
set-up can be made to work as a two-particle emitter. We examine the precision
with which the current can be nullified and with which the second cavity
effectively counts the particles emitted by the first one. To achieve
single-particle detection we examine pulsed cavities.


title:
Low-density, one dimensional quantum gases in the presence of a
  localised attractive potential

abstract:
  We investigate low-density, quantum-degenerate gases in the presence of a
localised attractive potential in the centre of a one-dimensional harmonic
trap.The attractive potential is modelled using a parameterised delta-function,
allowing us to determine all single particle eigenfunctions analytically. From
these we calculate the ground state many-body properties for a system of
spin-polarised fermions and, using the Bose-Fermi mapping theorem, extend the
results to strongly interacting bosonic systems. We discuss the single particle
densities, the pair correlation functions, the reduced single particle density
matrices and the momentum distributions as a function of particle number and
strength of the attractive point potential. As an important experimental
observable, we place special emphasis on spatial coherence properties of such
samples.


title:
The Sivashinsky equation for corrugated flames in the large-wrinkle
  limit

abstract:
  Sivashinsky's (1977) nonlinear integro-differential equation for the shape of
corrugated 1-dimensional flames is ultimately reducible to a 2N-body problem,
involving the 2N complex poles of the flame slope. Thual, Frisch & Henon (1985)
derived singular linear integral equations for the pole density in the limit of
large steady wrinkles $(N \gg 1)$, which they solved exactly for monocoalesced
periodic fronts of highest amplitude of wrinkling and approximately otherwise.
Here we solve those analytically for isolated crests, next for monocoalesced
then bicoalesced periodic flame patterns, whatever the (large-) amplitudes
involved. We compare the analytically predicted pole densities and flame shapes
to numerical results deduced from the pole-decomposition approach. Good
agreement is obtained, even for moderately large Ns. The results are extended
to give hints as to the dynamics of supplementary poles. Open problems are
evoked.


title: Non-demolishing measurement of a spin qubit state via Fano resonance

abstract:
  Fano resonances are proposed to perform a measurement of a spin state
(whether it is up or down) of a single electron in a quantum dot via a
spin-polarized current in an adjacent quantum wire. Rashba-like spin-orbit
interaction in a quantum dot prohibits spin-flip events (Kondo-like
phenomenon). That ensures the measurement to be non-demolishing.


title: Estimating total momentum at finite distances

abstract:
  We study the difficulties associated with the evaluation of the total Bondi
momentum at finite distances around the central source of a general
(asymptotically flat) spacetime. Since the total momentum is only rigorously
defined at future null infinity, both finite distance and gauge effects must be
taken into account for a correct computation of this quantity.
  Our discussion is applicable in general contexts but is particularly relevant
in numerically constructed spacetimes for both extracting important physical
information and assessing the accuracy of additional quantities.


title: On Sequences with Non-Learnable Subsequences

abstract:
  The remarkable results of Foster and Vohra was a starting point for a series
of papers which show that any sequence of outcomes can be learned (with no
prior knowledge) using some universal randomized forecasting algorithm and
forecast-dependent checking rules. We show that for the class of all
computationally efficient outcome-forecast-based checking rules, this property
is violated. Moreover, we present a probabilistic algorithm generating with
probability close to one a sequence with a subsequence which simultaneously
miscalibrates all partially weakly computable randomized forecasting
algorithms. %subsequences non-learnable by each randomized algorithm.
  According to the Dawid's prequential framework we consider partial recursive
randomized algorithms.


title: Thermohaline mixing in low-mass giants

abstract:
  Thermohaline mixing has recently been proposed to occur in low mass red
giants, with large consequences for the chemical yields of low mass stars. We
investigate the role of thermohaline mixing during the evolution of stars
between 1Msun and 3Msun, in comparison to other mixing processes acting in
these stars. We confirm that thermohaline mixing has the potential to destroy
most of the ^3He which is produced earlier on the main sequence during the red
giant stage. In our models we find that this process is working only in stars
with initial mass M <~ 1.5Msun. Moreover, we report that thermohaline mixing
can be present during core helium burning and beyond in stars which still have
a ^3He reservoir. While rotational and magnetic mixing is negligible compared
to the thermohaline mixing in the relevant layers, the interaction of
thermohaline motions with differential rotation and magnetic fields may be
essential to establish the time scale of thermohaline mixing in red giants.


title: Magnetotransport in non-planar SiGe/Si nanomembranes

abstract:
  We investigate the relationship between electronics and geometry in a
nonplanar SiGe/Si resonant quantum cavity (RQC) subject to a magnetic field.
The transfer matrix technique originally due to Usuki and coworkers (Phys. Rev.
B 52, 8244 1995) has been modified to account for the nonzero local curvature
of the RQC. Our results demonstrate that low-temperature ballistic
magnetoconductance in nonplanar RQCs is highly sensitive to the changes in
curvature for a wide range of magnetic field strengths.


title: Approximability and parameterized complexity of minmax values

abstract:
  We consider approximating the minmax value of a multi-player game in
strategic form. Tightening recent bounds by Borgs et al., we observe that
approximating the value with a precision of epsilon log n digits (for any
constant epsilon>0 is NP-hard, where n is the size of the game. On the other
hand, approximating the value with a precision of c log log n digits (for any
constant c >= 1) can be done in quasi-polynomial time. We consider the
parameterized complexity of the problem, with the parameter being the number of
pure strategies k of the player for which the minmax value is computed. We show
that if there are three players, k=2 and there are only two possible rational
payoffs, the minmax value is a rational number and can be computed exactly in
linear time. In the general case, we show that the value can be approximated
with any polynomial number of digits of accuracy in time n^(O(k)). On the other
hand, we show that minmax value approximation is W[1]-hard and hence not likely
to be fixed parameter tractable. Concretely, we show that if k-CLIQUE requires
time n^(Omega(k)) then so does minmax value computation.


title: On cotilting cotorsion and torsion pairs

abstract:
  In this paper we study cotorsion and torsion pairs induced by cotilting
modules. We prove the existence of a strong relationship between the
$\Sigma$-pure injectivity of the cotilting module and the property of the
induced cotorsion pair to be of finite type. In particular for cotilting
modules of injective dimension at most 1, or for noetherian rings, the two
notions are equivalent. On the other hand we prove that a torsion pair is
cogenerated by a $\Sigma$-pure injective cotilting module if and only if its
heart is a locally noetherian Grothendieck category. Moreover we prove that any
ring admitting a $\Sigma$-pure injective cotilting module of injective
dimension at most 1 is necessarily coherent. Finally, for noetherian rings, we
characterize cotilting torsion pairs induced by $\Sigma$-pure injective
cotilting modules.


title: Magneto-Thermohaline Mixing in Red Giants

abstract:
  We revise a magnetic buoyancy model that has recently been proposed as a
mechanism for extra mixing in the radiative zones of low-mass red giants. The
most important revision is our accounting of the heat exchange between rising
magnetic flux rings and their surrounding medium. This increases the buoyant
rising time by five orders of magnitude, therefore the number of magnetic flux
rings participating in the mixing has to be increased correspondingly. On the
other hand, our revised model takes advantage of the fact that the mean
molecular weight of the rings formed in the vicinity of the hydrogen burning
shell has been reduced by 3He burning. This increases their thermohaline
buoyancy (hence, decreases the total ring number) considerably, making it
equivalent to the pure magnetic buoyancy produced by a frozen-in toroidal field
with B_phi ~ 10 MG. We emphasize that some toroidal field is still needed for
the rings to remain cohesive while rising. Besides, this field prevents the
horizontal turbulent diffusion from eroding the mu contrast between the rings
and their surrounding medium. We propose that the necessary toroidal magnetic
field is generated by differential rotation of the radiative zone, that
stretches a pre-existing poloidal field around the rotation axis, and that
magnetic flux rings are formed as a result of its buoyancy-related instability.


title: Electron mobility in silicon nanowires

abstract:
  The low-field electron mobility in rectangular silicon nanowire (SiNW)
transistors was computed using a self-consistent Poisson-Schr\"{o}dinger-Monte
Carlo solver. The behavior of the phonon-limited and surface-roughness-limited
components of the mobility was investigated by decreasing the wire width from
30 nm to 8 nm, the width range capturing a crossover between two-dimensional
(2D) and one-dimensional (1D) electron transport. The phonon-limited mobility,
which characterizes transport at low and moderate transverse fields, is found
to decrease with decreasing wire width due to an increase in the
electron-phonon wavefunction overlap. In contrast, the mobility at very high
transverse fields, which is limited by surface roughness scattering, increases
with decreasing wire width due to volume inversion. The importance of acoustic
phonon confinement is also discussed briefly.


title:
A refinement of the Gribov-Zwanziger approach in the Landau gauge:
  infrared propagators in harmony with the lattice results

abstract:
  Recent lattice data have reported an infrared suppressed, positivity
violating gluon propagator which is nonvanishing at zero momentum and a ghost
propagator which is no longer enhanced. This paper discusses how to obtain
analytical results which are in qualitative agreement with these lattice data
within the Gribov-Zwanziger framework. This framework allows one to take into
account effects related to the existence of gauge copies, by restricting the
domain of integration in the path integral to the Gribov region. We elaborate
to great extent on a previous short paper by presenting additional results,
also confirmed by the numerical simulations. A detailed discussion on the soft
breaking of the BRST symmetry arising in the Gribov-Zwanziger approach is
provided.


title:
One-loop corrections to the string tension of the vortex in the Abelian
  Higgs model

abstract:
  We present an exact numerical computation of the one-loop correction of the
string tension for the Nielsen-Olesen vortex in the Abelian Higgs model. The
computations proceeds via the computation of the Euclidean Green's function for
the gauge, Higgs and Faddeev-Popov fields using mode functions, and taking the
appropriate trace. Renormalization is an essential part of this computation, it
is done by removing leading order contributions from the numerical results so
as to make these finite, and to add the divergent parts back, after suitable
regularization and renormalization. We encounter and solve some problems which
are specific to gauge theories and topological solutions. The corrections to
the energy are found to be sizeable, but still smaller than the classical
energy as long as g**2 is smaller than unity.


title: The large CP phase in B(s) - anti-B(s) mixing and Unparticle Physics

abstract:
  In this work we investigate the contribution to B(d,s) mixing from both
scalar and vector unparticles in a number of scenarios. The emphasis of this
work is to show the impact of the recently discovered 3 sigma evidence for new
physics found in the CP phase of B(s) mixing. Here we show that the inclusion
of the CP phase constraints for both B(d) and B(s) mixing improves the bounds
set on the unparticle couplings by a factor of 2~4, and one particular scenario
of scalar unparticles is found to be excluded by the 3 sigma measurement of
phi(s).


title:
Addendum: Ultrahigh-energy cosmic-ray bounds on nonbirefringent
  modified-Maxwell theory

abstract:
  Nonbirefringent modified-Maxwell theory, coupled to standard Dirac particles,
involves nine dimensionless parameters, which can be bounded by the inferred
absence of vacuum Cherenkov radiation for ultrahigh-energy cosmic rays
(UHECRs). With selected UHECR events, two-sided bounds on the eight
nonisotropic parameters are obtained at the 10^{-18} level, together with an
improved one-sided bound on the single isotropic parameter at the 10^{-19}
level.


title: Invariants associated with linear ordinary differential equations

abstract:
  We apply a novel method for the equivalence group and its infinitesimal
generators to the investigation of invariants of linear ordinary differential
equations. First, a comparative study of this method is illustrated by an
example. Next, the method is used to obtain the invariants of low order linear
ordinary differential equations, and the structure invariance group for an
arbitrary order of these equations. Other properties of these equations are
also discussed, including the exact number of their invariants.


title: Toward a homogeneous set of transiting planet parameters

abstract:
  With 40 or more transiting exoplanets now known, the time is ripe to seek
patterns and correlations among their observed properties, which may give
important insights into planet formation, structure, and evolution. This task
is made difficult by the widely different methodologies that have been applied
to measure their properties in individual cases. Furthermore, in many systems
our knowledge of the planet properties is limited by the knowledge of the
properties of the parent stars. To address these difficulties we have
undertaken the first comprehensive analysis of the data for 23 transiting
planets using a uniform methodology. We revisit several of the recently
proposed correlations, and find new ones involving the metallicity of the
parent stars.


title:
Some improvements of the ART method for finding transition pathways on
  potential energy surfaces

abstract:
  The Activation-Relaxation Technique nouveau (ARTn) is an eigenvector
following method for systematic search of saddle points and transition pathways
on a given potential energy surface. We propose a variation of this method
aiming at improving the efficiency of the local convergence close to the saddle
point. We prove the convergence and robustness of this new algorithm. The
efficiency of the method is tested in the case of point defects in body
centered cubic iron.


title: Domain walls in Born-Infeld-dilaton background

abstract:
  We study the dynamics of domain walls in Einstein-Born-Infeld-dilaton theory.
Dilaton is non-trivially coupled with the Born-Infeld electromagnetic field. We
find three different types of solutions consistent with the dynamic domain
walls. For every case, the solutions have singularity. Further more, in these
backgrounds, we study the dynamics of domain walls. We qualitatively plot
various form of the bulk metrics and the potential encountered by the domain
walls. In many cases, depending upon the value of the parameters, the domain
walls show bouncing universe and also undergo inflationary phase followed by
standard decelerated expansion.


title:
Compact supersymmetric solutions of the heterotic equations of motion in
  dimensions 7 and 8

abstract:
  We construct explicit compact solutions with non-zero field strength,
non-flat instanton and constant dilaton to the heterotic string equations in
dimensions seven and eight. We present a quadratic condition on the curvature
which is necessary and sufficient the heterotic supersymmetry and the anomaly
cancellation to imply the heterotic equations of motion in dimensions seven and
eight. We show that some of our examples are compact supersymmetric solutions
of the heterotic equations of motion in dimensions seven and eight.


title:
Magnetic-field induced quantum-size cascades in superconducting
  nanowires

abstract:
  In high-quality nanowires, quantum confinement of the transverse electron
motion splits the band of single-electron states in a series of subbands. This
changes in a qualitative way the scenario of the magnetic-field induced
superconductor-to-normal transition. We numerically solve the Bogoliubov-de
Gennes equations for a clean metallic cylindrical nanowire at zero temperature
in a parallel magnetic field and find that for diameters D < 10-15 nm, this
transition occurs as a cascade of subsequent jumps in the order parameter (this
is opposed to the smooth second-order phase transition in the mesoscopic
regime). Each jump is associated with the depairing of electrons in one of the
single-electron subbands. As a set of subbands contribute to the order
parameter, the depairing process occurs as a cascade of jumps. We find
pronounced quantum-size oscillations of the critical magnetic field with giant
resonant enhancements. In addition to these orbital effects, the paramagnetic
breakdown of Cooper pairing also contributes but only for smaller diameters, i.
e., D < 5 nm.


title: Speed of Sound in String Gas Cosmology

abstract:
  We consider an ensemble of closed strings in a compact space with stable one
cycles and compute the speed of sound resulting from string thermodynamics.
Possible applications to the issue of Jeans instability in string gas cosmology
are mentioned.


title: Group-invariant solutions of a nonlinear acoustics model

abstract:
  Based on a recent classification of subalgebras of the symmetry algebra of
the Zabolotskaya-Khokhlov equation, all similarity reductions of this equation
into ordinary differential equations are obtained. Large classes of
group-invariant solutions of the equation are also determined, and some
properties of the reduced equations and exact solutions are discussed.


title:
On submanifolds with recurrent second fundamental form in spaces of
  constant curvature

abstract:
  The complete local classification and geometric description of n-dimensional
submanifolds F with recurrent nonparallel second fundamental form in the spaces
of constant curvature M(c) are obtained in this article.


title: Space Efficient Multi-Dimensional Range Reporting

abstract:
  We present a data structure that supports three-dimensional range reporting
queries in $O(\log \log U + (\log \log n)^3+k)$ time and uses $O(n\log^{1+\eps}
n)$ space, where $U$ is the size of the universe, $k$ is the number of points
in the answer,and $\eps$ is an arbitrary constant. This result improves over
the data structure of Alstrup, Brodal, and Rauhe (FOCS 2000) that uses
$O(n\log^{1+\eps} n)$ space and supports queries in $O(\log n+k)$ time,the data
structure of Nekrich (SoCG'07) that uses $O(n\log^{3} n)$ space and supports
queries in $O(\log \log U + (\log \log n)^2 + k)$ time, and the data structure
of Afshani (ESA'08) that uses $O(n\log^{3} n)$ space and also supports queries
in $O(\log \log U + (\log \log n)^2 + k)$ time but relies on randomization
during the preprocessing stage. Our result allows us to significantly reduce
the space usage of the fastest previously known static and incremental
$d$-dimensional data structures, $d\geq 3$, at a cost of increasing the query
time by a negligible $O(\log \log n)$ factor.


title: Gravito-magnetic instabilities in anisotropically expanding fluids

abstract:
  Gravitational instabilities in a magnetized Friedman - Robertson - Walker
(FRW) Universe, in which the magnetic field was assumed to be too weak to
destroy the isotropy of the model, are known and have been studied in the past.
Accordingly, it became evident that the external magnetic field disfavors the
perturbations' growth, suppressing the corresponding rate by an amount
proportional to its strength. However, the spatial isotropy of the FRW Universe
is not compatible with the presence of large-scale magnetic fields. Therefore,
in this article we use the general-relativistic (GR) version of the
(linearized) perturbed magnetohydrodynamic equations with and without
resistivity, to discuss a generalized Jeans criterion and the potential
formation of density condensations within a class of homogeneous and
anisotropically expanding, self-gravitating, magnetized fluids in curved
space-time. We find that, for a wide variety of anisotropic cosmological
models, gravito-magnetic instabilities can lead to sub-horizonal, magnetized
condensations. In the non-resistive case, the power spectrum of the unstable
cosmological perturbations suggests that most of the power is concentrated on
large scales (small k), very close to the horizon. On the other hand, in a
resistive medium, the critical wave-numbers so obtained, exhibit a delicate
dependence on resistivity, resulting in the reduction of the corresponding
Jeans lengths to smaller scales (well bellow the horizon) than the
non-resistive ones, while increasing the range of cosmological models which
admit such an instability.


title:
From MAGIC to CTA: the INAF participation to Cherenkov Telescopes
  experiments for Very High Energy Astrophysics

abstract:
  The next decade can be considered the "golden age" of the Gamma Ray Astronomy
with the two satellites for Gamma Ray Astronomy (AGILE and GLAST) in orbit.
Therefore, thanks to many other X-ray experiments already in orbit (e.g. Swift,
Chandra, NewtonXMM, etc.) it will be possible to image the Universe for the
first time all over the electromagnetic spectrum almost contemporarily. The new
generations of ground-based very high gamma-ray instruments are ready to extend
the observed band also to the very high frequencies. Scientists from the
Italian National Institute for Astrophysics (INAF) are involved in many, both
space- and ground- based gamma ray experiments, and recently such an
involvement has been largely improved in the field of the Imaging Atmospheric
Cherenkov Telescopes (IACT). INAF is now member of the MAGIC collaboration and
is participating to the realization of the second MAGIC telescope. MAGIC, as
well other IACT experiments, is not operated as an observatory so a proper
guest observer program does not exist. A consortium of European scientists
(including INAF scientists) is thus now thinking to the design of a new
research infrastructure: the Cherenkov Telescope Array (CTA). CTA is conceived
to provide 10 times the sensitivity of current instruments, combined with
increased flexibility and increased coverage from some 10 GeV to some 100 TeV.
CTA will be operated as an observatory to serve a wider community of astronomer
and astroparticle physicists.


title: Consistent Decoupling of Heavy Scalars and Moduli in N=1 Supergravity

abstract:
  We consider the conditions for integrating out heavy chiral fields and moduli
in N=1 supergravity, subject to two explicit requirements. First, the
expectation values of the heavy fields should be unaffected by low energy
phenomena. Second, the low energy effective action should be described by N=1
supergravity. This leads to a working definition of decoupling in N=1
supergravity that is different from the usual condition of gravitational
strength couplings between sectors, and that is the relevant one for inflation
with moduli stabilization, where some light fields (the inflaton) can have long
excursions in field space. It is also important for finding de Sitter vacua in
flux compactifications and KKLT scenarios, since failure of the decoupling
condition invalidates the implicit assumption that the stabilization and
uplifting potentials have a low energy supergravity description.
  We derive a sufficient condition for supersymmetric decoupling, namely, that
the Kahler invariant function G = K + log |W|^2 is of the form G = L(light,
(heavy)) with H and L arbitrary functions, which includes the particular case G
= L(light) + H(heavy). The consistency condition does not hold in general for
the ansatz K = K(light) + K(heavy), W = W(light) + W(heavy) and we discuss
under what circumstances it does hold.


title: A Novel View on the Physical Origin of E8

abstract:
  We consider a straightforward extension of the 4-dimensional spacetime $M_4$
to the space of extended events associated with strings/branes, corresponding
to points, lines, areas, 3-volumes, and 4-volumes in $M_4$. All those objects
can be elegantly represented by the Clifford numbers $X\equiv x^A \gamma_A
\equiv x^{a_1 ...a_r} \gamma_{a_1 ...a_r}, r=0,1,2,3,4$. This leads to the
concept of the so-called Clifford space ${\cal C}$, a 16-dimensional manifold
whose tangent space at every point is the Clifford algebra ${\cal C \ell
}(1,3)$. The latter space besides an algebra is also a vector space whose
elements can be rotated into each other in two ways: (i) either by the action
of the rotation matrices of SO(8,8) on the components $x^A$ or (ii) by the left
and right action of the Clifford numbers $R=$exp$ [\alpha^A \gam_A]$ and
$S=$exp$ [\beta^A \gam_A]$ on $X$. In the latter case, one does not recover all
possible rotations of the group SO(8,8). This discrepancy between the
transformations (i) and (ii) suggests that one should replace the tangent space
${\cal C \ell}(1,3)$ with a vector space $V_{8,8}$ whose basis elements are
generators of the Clifford algebra ${\cal C \ell}(8,8)$, which contains the Lie
algebra of the exceptional group E$_8$ as a subspace. E$_8$ thus arises from
the fact that, just as in the spacetime $M_4$ there are $r$-volumes generated
by the tangent vectors of the spacetime, there are $R$-volumes,
$R=0,1,2,3,...,16$, in the Clifford space ${\cal C}$, generated by the tangent
vectors of ${\cal C}$.


title: Viscosity and the Soft Ridge at RHIC

abstract:
  Correlation studies exhibit a ridge-like feature in rapidity and azimuthal
angle, with and without a jet trigger. We ask whether the feature in
untriggered correlations can be a consequence of transverse flow and viscous
diffusion.


title: The Orientation of the Eta Carinae Binary System

abstract:
  We examine a variety of observations that shed light on the orientation of
the semi-major axis of the Eta Carinae massive binary system. Under several
assumptions we study the following observations: The Doppler shifts of some He
I P-Cygni lines that is attributed to the secondary's wind, of one Fe II line
that is attributed to the primary's wind, and of the Paschen emission lines
which are attributed to the shocked primary's wind, are computed in our model
and compared with observations. We compute the hydrogen column density toward
the binary system in our model, and find a good agreement with that deduced
from X-ray observations. We calculate the ionization of surrounding gas blobs
by the radiation of the hotter secondary star, and compare with observations of
a highly excited [Ar III] narrow line. We find that all of these support an
orientation where for most of the time the secondary - the hotter less massive
star - is behind the primary star. The secondary comes closer to the observer
only for a short time near periastron passage, in its highly eccentric (e~0.9)
orbit. Further supporting arguments are also listed, followed by discussion of
some open and complicated issues.


title: Multiple kinetic k-essence, phantom barrier crossing and stability

abstract:
  We investigate models of dark energy with purely kinetic multiple k-essence
sources that allow for the crossing of the phantom divide line, without
violating the conditions of stability. It is known that with more than one
kinetic k-field one can possibly construct dark energy models whose equation of
state parameter $\wx$ crosses -1 (the phantom barrier) at recent red-shifts, as
indicated by the Supernova Ia and other observational probes. However, such
models may suffer from cosmological instabilities, as the effective speed of
propagation $\cx$ of the dark energy density perturbations may become {\it
imaginary} while the $\wx = -1$ barrier is crossed. Working out the expression
for $\cx$ we show that multiple kinetic k-essence fields do indeed lead to a
$\wx = -1$ crossing dark energy model, satisfying the stability criterion
$\cx^2 \geq 0$ as well as the condition $\cx \leq 1$ (in natural units), which
implies that the dark energy is not super-luminal. As a specific example, we
construct a phantom barrier crossing model involving three k-fields for which
$\cx$ is a constant, lying between 0 and 1. The model fits well with the latest
Supernova Ia Union data, and the best fit shows that $\wx$ crosses -1 at
red-shift $z \sim 0.2$, whereas the dark energy density nearly tracks the
matter density at higher red-shifts.


title:
Carbonyl sulphide under strong laser field: time-dependent density
  functional theory

abstract:
  The first 52 fs of a time evolution of the electron density in OCS after an
interaction with an intense sub 10 fs laser pulse are studied using the
time-dependent density functional theory. The nuclear motion in this linear
trimer is simulated by the classical molecular dynamics method. Laser fields of
intensity 10^{13} W/cm^2 and 10^{15} W/cm^2 are used. Details of the laser
induced changes of the structure, as well as the ionization rate are sensitive
to the applied field intensity and its polarization. It is found that under
suitable conditions the OCS molecule bends soon after an interaction with a
laser pulse. A deviation from the linear geometry of up to 23.6^\circ and
charged ions of up to +3 are observed. The time evolution of electric dipole
moments and the time-dependent electron localization function (ELF) are also
studied.


title: Superstring measure and non-renormalization of the three-point amplitude

abstract:
  We show that a recently conjectured expression for the superstring
three-point amplitude, in the framework of the Cacciatori, Dalla Piazza, van
Geemen - Grushevsky ansatz for the chiral measure, fails to vanish at
three-loop, in contrast with expectations from non-renormalization theorems.
Based on analogous two-loop computations, we discuss the possibility of a
non-trivial correction to the amplitude and propose a natural candidate for
such a contribution. Thanks to a new remarkable identity, it is reasonable to
expect that the corrected three-point amplitude vanishes at three-loop,
recovering the agreement with non-renormalization theorems.


title: Flavor Twisted Boundary Conditions in the Breit Frame

abstract:
  We use a generalization of chiral perturbation theory to account for the
effects of flavor twisted boundary conditions in the Breit frame. The relevant
framework for two light flavors is an SU(6|4) partially quenched theory, where
the extra valence quarks differ only by their boundary conditions. Focusing on
the pion electromagnetic form factor, finite volume corrections are calculated
at next-to-leading order in the chiral expansion and are estimated to be small
on current lattices.


title: The 1-fixed-endpoint Path Cover Problem is Polynomial on Interval Graph

abstract:
  We consider a variant of the path cover problem, namely, the
$k$-fixed-endpoint path cover problem, or kPC for short, on interval graphs.
Given a graph $G$ and a subset $\mathcal{T}$ of $k$ vertices of $V(G)$, a
$k$-fixed-endpoint path cover of $G$ with respect to $\mathcal{T}$ is a set of
vertex-disjoint paths $\mathcal{P}$ that covers the vertices of $G$ such that
the $k$ vertices of $\mathcal{T}$ are all endpoints of the paths in
$\mathcal{P}$. The kPC problem is to find a $k$-fixed-endpoint path cover of
$G$ of minimum cardinality; note that, if $\mathcal{T}$ is empty the stated
problem coincides with the classical path cover problem. In this paper, we
study the 1-fixed-endpoint path cover problem on interval graphs, or 1PC for
short, generalizing the 1HP problem which has been proved to be NP-complete
even for small classes of graphs. Motivated by a work of Damaschke, where he
left both 1HP and 2HP problems open for the class of interval graphs, we show
that the 1PC problem can be solved in polynomial time on the class of interval
graphs. The proposed algorithm is simple, runs in $O(n^2)$ time, requires
linear space, and also enables us to solve the 1HP problem on interval graphs
within the same time and space complexity.


title:
A simple proof of the recent generalisations of Hawking's black hole
  topology theorem

abstract:
  A key result in four dimensional black hole physics, since the early 1970s,
is Hawking's topology theorem asserting that the cross-sections of an "apparent
horizon", separating the black hole region from the rest of the spacetime, are
topologically two-spheres. Later, during the 1990s, by applying a variant of
Hawking's argument, Gibbons and Woolgar could also show the existence of a
genus dependent lower bound for the entropy of topological black holes with
negative cosmological constant. Recently Hawking's black hole topology theorem,
along with the results of Gibbons and Woolgar, has been generalised to the case
of black holes in higher dimensions. Our aim here is to give a simple
self-contained proof of these generalisations which also makes their range of
applicability transparent.

categories: gr-qc hep-th math-ph math.DG math.GT math.MP


title:
Mach-like Angular Correlations Arise Only From the Head Zone of AdS/CFT
  String Jets

abstract:
  We show that Mach-like azimuthal correlations of associated hadrons in the
wake of heavy quark jets modeled in the AdS/CFT string drag picture originate
only from the near-quark ``Head'' region. The contributions from the far zones
lead only to a yield peaked in the opposite direction with respect to the
trigger jet.


title: The triangle-free process

abstract:
  Consider the following stochastic graph process. We begin with the empty
graph on n vertices and add edges one at a time, where each edge is chosen
uniformly at random from the collection of potential edges that do not form
triangles when added to the graph. The process terminates at a maximal
traingle-free graph. Here we analyze the triangle-free process, determining the
likely order of magnitude of the number of edges in the final graph. As a
corollary we show that the triangle-free process is very likely to produce a
Ramsey R(3,t) graph; that is, our analysis of the triangle-free process gives a
new proof of the lower bound on R(3,t) previously established by Jeong Han Kim.
The techniques introduced extend to the K_4-free process thereby establishing a
small improvement in the best known lower bound on the Ramsey number R(4,t).


title: A "Crib Sheet" for Supernova Events

abstract:
  This paper summarizes our theoretical understanding of supernova events in a
"back of the envelope" way. It is intended to aid in the recognition and
understanding of those events which are not "standard", and which may provide
the most insight.


title:
Spectral and scattering theory for space-cutoff $P(\varphi)_{2}$ models
  with variable metric

abstract:
  We consider space-cutoff $P(\varphi)_{2}$ models with a variable metric of
the form \[ H= \d\G(\omega)+ \int_{\rr}g(x):P(x, \varphi(x)):\d x, \] on the
bosonic Fock space $L^{2}(\rr)$, where the kinetic energy $\omega= h^{\12}$ is
the square root of a real second order differential operator \[ h= Da(x)D+
c(x), \] where the coefficients $a(x), c(x)$ tend respectively to 1 and
$m_{\infty}^{2}$ at $\infty$ for some $m_{\infty}>0$. The interaction term
$\int_{\rr}g(x):P(x, \varphi(x)):\d x$ is defined using a bounded below
polynomial in $\lambda$ with variable coefficients $P(x, \lambda)$ and a
positive function $g$ decaying fast enough at infinity. We extend in this paper
the results of \cite{DG} where $h$ had constant coefficients and $P(x,
\lambda)$ was independent of $x$. We describe the essential spectrum of $H$,
prove a Mourre estimate outside a set of thresholds and prove the existence of
asymptotic fields. Our main result is the {\em asymptotic completeness} of the
scattering theory, which means that the CCR representation given by the
asymptotic fields is of Fock type, with the asymptotic vacua equal to bound
states of $H$. As a consequence $H$ is unitarily equivalent to a collection of
second quantized Hamiltonians. An important role in the proofs is played by the
{\em higher order estimates}, which allow to control powers of the number
operator by powers of the resolvent. To obtain these estimates some conditions
on the eigenfunctions and generalized eigenfunctions of $h$ are necessary. We
also discuss similar models in higher space dimensions where the interaction
has an ultraviolet cutoff.


title: Vortex pseudomomentum and dissipation in a superfluid vortex lattice

abstract:
  We propose an alternative approach to the dissipative vortex dynamics
occurring in a superfluid vortex lattice at finite temperatures. Focusing upon
the pseudomomentum of a vortex and its surrounding quasiparticles, we derive an
equation of motion which, in spite of yielding the same evolution as the usual
one for massless vortices, does not involve the vortex mass. This picture could
provide further insights into the controversy about the nature of the vortex
mass.


title:
The modification of Einstein`s gravitational field equation following
  from the energy conservation law

abstract:
  The cause of an infringement in GR of a gravitational field energy
conservation law is investigated . The equation of a gravitational field not
contradicting to the energy conservation law is suggested. This equation
satisfy to the Einstein,s requirement of equivalence of all energy kinds as
sources of a gravitational field. This equation is solved in paper for cosmic
objects. It is showed, that results for some objects - for black holes and
gravitating strings-essentialy differ from such for Einstein,s equation, have
the symple meaning and do not contradictions.


title:
Neutrino signatures and the neutrino-driven wind in Binary Neutron Star
  Mergers

abstract:
  We present VULCAN/2D multi-group flux-limited-diffusion radiation
hydrodynamics simulations of binary neutron star (BNS) mergers, using the Shen
equation of state, covering ~100 ms, and starting from azimuthal-averaged 2D
slices obtained from 3D SPH simulations of Rosswog & Price for 1.4 Msun
(baryonic) neutron stars with no initial spins, co-rotating spins, and
counter-rotating spins. Snapshots are post-processed at 10 ms intervals with a
multi-angle neutrino-transport solver. We find polar-enhanced neutrino
luminosities, dominated by $\bar{\nu}_e$ and ``$\nu_\mu$'' neutrinos at peak,
although $\nu_e$ emission may be stronger at late times. We obtain typical peak
neutrino energies for $\nu_e$, $\bar{\nu}_e$, and ``$\nu_\mu$'' of ~12, ~16,
and ~22 MeV. The super-massive neutron star (SMNS) formed from the merger has a
cooling timescale of ~1 s. Charge-current neutrino reactions lead to the
formation of a thermally-driven bipolar wind with <$\dot{M}$> ~10$^{-3}$
Msun/s, baryon-loading the polar regions, and preventing any production of a
GRB prior to black-hole formation. The large budget of rotational free energy
suggests magneto-rotational effects could produce a much greater polar mass
loss. We estimate that ~10$^{-4}$ Msun of material with electron fraction in
the range 0.1-0.2 become unbound during this SMNS phase as a result of neutrino
heating. We present a new formalism to compute the $\nu_i\bar{\nu}_i$
annihilation rate based on moments of the neutrino specific intensity computed
with our multi-angle solver. Cumulative annihilation rates, which decay as
$t^{-1.8}$, decrease over our 100 ms window from a few 10$^{50}$ to ~10$^{49}$
erg/s, equivalent to a few 10$^{54}$ to ~10$^{53}$ $e^-e^+$ pairs per second.


title:
Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite
  Luminosity Function

abstract:
  We correct the observed Milky Way satellite luminosity function for
luminosity bias using published completeness limits for the Sloan Digital Sky
Survey DR5. Assuming that the spatial distribution of Milky Way satellites
tracks the subhalos found in the Via Lactea LCDM N-body simulation, we show
that there should be between ~300 and ~600 satellites within 400 kpc of the Sun
that are brighter than the faintest known dwarf galaxies, and that there may be
as many as ~ 1000, depending on assumptions. By taking into account
completeness limits, we show that the radial distribution of known Milky Way
dwarfs is consistent with our assumption that the full satellite population
tracks that of subhalos. These results alleviate the primary worries associated
with the so-called missing satellites problem in CDM. We show that future, deep
wide-field surveys such as SkyMapper, the Dark Energy Survey (DES), PanSTARRS,
and the Large Synoptic Survey Telescope (LSST) will deliver a complete census
of ultra-faint dwarf satellites out to the Milky Way virial radius, offer new
limits on the free-streaming scale of dark matter, and provide unprecedented
constraints on the low-luminosity threshold of galaxy formation.


title: Superconducting loop quantum gravity and the cosmological constant

abstract:
  We argue that the cosmological constant is exponentially suppressed in a
candidate ground state of loop quantum gravity as a nonperturbative effect of a
holographic Fermi-liquid theory living on a two-dimensional spacetime. Ashtekar
connection components, corresponding to degenerate gravitational configurations
breaking large gauge invariance and CP symmetry, behave as composite fermions
that condense as in Bardeen-Cooper-Schrieffer theory of superconductivity.
Cooper pairs admit a description as wormholes on a de Sitter boundary.


title:
Valence-Bond Dynamical Mean-Field Theory of Doped Mott Insulators with
  Nodal/Antinodal Differentiation

abstract:
  We introduce a valence-bond dynamical mean-field theory of doped Mott
insulators. It is based on a minimal cluster of two orbitals, each associated
with a different region of momentum space and hybridized to a self-consistent
bath. The low-doping regime is characterized by singlet formation and the
suppression of quasiparticles in the antinodal regions, leading to the
formation of Fermi arcs. This is described in terms of an orbital-selective
transition in reciprocal space. The calculated tunneling and photoemission
spectra are consistent with the phenomenology of the normal state of cuprates.
We derive a low-energy description of these effects using a generalization of
the slave-boson method.


title:
Infrared and millimetre-wavelength evidence for cold accretion within a
  z = 2.83 Lyman-alpha blob

abstract:
  This paper discusses infrared and millimetre-wavelength observations of a
Lyman-alpha blob discovered by Smith & Jarvis, a candidate for ionization by
the cold accretion scenario discussed in Fardal et al. and Dijkstra et al. We
have observed the counterpart galaxy at infrared wavelengths in deep
observations with the Spitzer Space Telescope using the IRAC 3.6, 4.5, 5.8 &
8.0 micron and MIPS 24 micron bands, as well as using the Max-Planck Millimeter
Bolometer Array at a wavelength of 1.2mm with the IRAM 30 metre telescope.
These observations probe the > 95kpc Lyman-alpha halo for the presence of
obscured AGN components or the presence of a violent period of star formation
invoked by other models of ionisation for these mysterious objects. 24 micron
observations suggest that an obscured AGN would be insufficiently luminous to
ionize the halo, and that the star formation rate within the halo may be as low
as <140 Msolar/yr depending on the model SED used. This is reinforced by our
observations at 1.2mm using MAMBO-2, which yield an upper limit of SFR <550
Msolar/yr from our non-detection to a 3 sigma flux limit of 0.86 mJy/beam.
Finding no evidence for either AGN or extensive star formation, we conclude
that this halo is ionised by a cold accretion process. We derive model SEDs for
the host galaxy, and use the Bruzual & Charlot and Maraston libraries to show
that the galaxy is well described by composite stellar populations of total
mass 3.42 +/- 0.13 x 10^11 Msolar or 4.35 +/- 0.16 x 10^11 Msolar depending on
the model SEDs used.


title: Nice inducing schemes and the thermodynamics of rational maps

abstract:
  We consider the thermodynamic formalism of a complex rational map $f$ of
degree at least two, viewed as a dynamical system acting on the Riemann sphere.
More precisely, for a real parameter $t$ we study the (non-)existence of
equilibrium states of $f$ for the potential $-t \ln |f'|$, and the analytic
dependence on $t$ of the corresponding pressure function. We give a fairly
complete description of the thermodynamic formalism of a rational map that is
"expanding away from critical points" and that has arbitrarily small "nice
sets" with some additional properties. Our results apply in particular to
non-renormalizable polynomials without indifferent periodic points, infinitely
renormalizable quadratic polynomials with a priori bounds, real quadratic
polynomials, topological Collet-Eckmann rational maps, and to backward
contracting rational maps. As an application, for these maps we describe the
dimension spectrum of Lyapunov exponents, and of pointwise dimensions of the
measure of maximal entropy, and obtain some level-1 large deviations results.


title: Axionic Extensions of the Supersymmetric Standard Model

abstract:
  The Supersymmetric Standard Model is a benchmark theoretical framework for
particle physics, yet it suffers from a number of deficiencies, chief among
which is the strong CP problem. Solving this with an axion in the context of
selected new particles, it is shown in three examples that other problems go
away automatically as well, resulting in (-)^L and (-)^{3B} conservation,
viable combination of two dark-matter candidates, successful baryogenesis,
seesaw neutrino masses, and verifiable experimental consequences at the TeV
energy scale.


title: The Late Stellar Assembly of Massive Cluster Galaxies Via Major Merging

abstract:
  We present multi-wavelength observations of the brightest galaxies in four
X-ray luminous groups at z~0.37 that will merge to form a cluster comparable in
mass to Coma. Ordered by increasing stellar mass, the four brightest group
galaxies (BGGs) present a time sequence where BGG-1, 2, and 3 are in merging
systems and BGG-4 is a massive remnant [M(stars)=6.7x10^(11) Msun]. BGG-1 and 2
have bright, gravitationally bound companions and BGG-3 has two nuclei
separated by only 2.5 kpc, thus merging at z<0.5 increases the BGG mass by >40%
(merging timescale<2 Gyr) and V-band luminosity by ~0.4 mag. The BGGs'
rest-frame (B-V) colors correspond to stellar ages of >3 Gyr, and their tight
scatter in (B-V) color [sigma(BV)=0.032] confirms they formed the bulk of their
stars at z>0.9. Optical spectroscopy shows no signs of recent (<1.5 Gyr) or
ongoing star formation. Only two BGGs are weakly detected at 24 microns, and
X-ray and optical data indicate the emission in BGG-2 is due to an AGN. All
four BGGs and their companions are early-type (bulge-dominated) galaxies, and
they are embedded in diffuse stellar envelopes up to ~140 kpc across. The four
BGG systems must evolve into the massive, red, early-type galaxies dominating
local clusters. Our results show that: 1) massive galaxies in groups and
clusters form via dissipationless merging; and 2) the group environment is
critical for this process.


title:
Evolution of environment dependent galaxy properties in the Sloan
  Digital Sky Survey

abstract:
  We use photometric redshifts to analyse the effect of local environment on
galaxy colours at redshifts z < 0.63 in the SDSS data release 6. We construct
mock SDSS-DR6 catalogues using semi-analytic galaxies to study possible
systematic effects on the characterisation of environment and colour statistics
due to the uncertainty in the determination of redshifts. We use the projected
galaxy density derived from the distance to the nearest neighbours with a
suitable radial velocity threshold to take into account the uncertainties in
the photometric redshift estimates. Our findings indicate that the use of
photometric redshifts greatly improves estimates of projected local galaxy
density when galaxy spectra are not available. We find a tight relationship
between spectroscopic and photometric derived densities, both in the SDSS-DR6
data (up to z=0.3) and mock catalogues (up to z=0.63).
  At z=0, faint galaxies show a clear increase of the red galaxy fraction as
the local density increases. Bright galaxies, on the other hand, show a
constant red galaxy fraction. We are able to track the evolution of this
fraction to z=0.55 for galaxies brighter than M_r=-21.5 and find that the
fraction of blue galaxies with respect to the total population progressively
becomes higher as the redshift increases, at a rate of 15% Gyr. Also, at any
given redshift, bright galaxies show a larger red population, indicating that
the star-formation activity shifts towards smaller objects as the redshift
decreases.


title: About a (standard model) universe dominated by the right matter

abstract:
  We analyze the phenomenology of a prolonged early epoch of matter domination
by an unstable but very long-lived massive particle. This new matter domination
era can help to relax some of the requirements on the primordial inflation. Its
main effect is the huge entropy production produced by the decays of such
particle that can dilute any possible unwanted relic, as the gravitino in
supersymmetric models, and thus relax the constraints on the inflationary
reheating temperature. Furthermore, a long period of matter domination reduces
the number of $e$-foldings after the horizon crossing by observable
perturbations and therefore the requirements on flatness of the inflationary
potential. A natural candidate for such heavy, long-lived particle already
present in the Standard Model of the electroweak interactions would be a heavy
right-handed neutrino. In this case, we show that its decays can also generate
the observed baryon asymmetry with right-handed neutrino masses well above the
bound from gravitino overproduction.


title:
Extending the baseline: Spitzer Mid-Infrared Photometry of Globular
  Cluster Systems in the Centaurus A and Sombrero Galaxies

abstract:
  Spitzer IRAC mid-infrared photometry is presented for the globular cluster
(GC) systems of the NGC 5128 ("Centaurus A") and NGC 4594 ("Sombrero")
galaxies. Existing optical photometric and spectroscopic are combined with this
new data in a comprehensive optical to mid-IR colour catalogue of 260 GCs.
Empirical colour-metallicity relationships are derived for all optical to
mid-IR colour combinations.
  These colours prove to be very effective quantities to test the photometric
predictions of simple stellar population (SSP) models. In general, four SSP
models show larger discrepancies between each other and the data at bluer
wavelengths, especially at high metallicities. Such differences become very
important when attempting to use colour-colour model predictions to constrain
the ages of stellar populations. Furthermore, the age-substructure determined
from colour-colour diagrams and 91 NGC 5128 GCs with spectroscopic ages from
Beasley et al. (2008) are inconsistent, suggesting any apparent GC system
age-substructure implied by a colour-colour analysis must be verified
independently.
  Unlike blue wavebands, certain optical to mid-IR colours are insensitive to
the flux from hot horizontal branch stars and thus provide an excellent
metallicity proxy. The NGC 5128 GC system shows strong bimodality in the
optical R-band to mid-IR colour distributions, hence proving it is bimodal in
metallicity. In this new colour space, a colour-magnitude trend, a "blue tilt",
is found in the NGC 5128 metal-poor GC data. The NGC 5128 young GCs do not
contribute to this trend. [abridged]


title: Prediction with Expert Advice in Games with Unbounded One-Step Gains

abstract:
  The games of prediction with expert advice are considered in this paper. We
present some modification of Kalai and Vempala algorithm of following the
perturbed leader for the case of unrestrictedly large one-step gains. We show
that in general case the cumulative gain of any probabilistic prediction
algorithm can be much worse than the gain of some expert of the pool.
Nevertheless, we give the lower bound for this cumulative gain in general case
and construct a universal algorithm which has the optimal performance; we also
prove that in case when one-step gains of experts of the pool have ``limited
deviations'' the performance of our algorithm is close to the performance of
the best expert.


title: RR Pictoris: an old nova showing superhumps and QPOs

abstract:
  We present time-resolved V-photometry of the old nova RR Pic. Apart from the
hump-like variability, the light curves show the strong flickering and random
variation typical for RR Pic. We do not find any convincing evidence for the
previously reported eclipse. The extrapolated eclipse phase coincides with a
broad minimum, but comparing the overall shape of the light curve suggests that
the eclipse should actually be located around phase 0.2. The orbital period
which we derive from these data agrees well with the old one, any uncertainty
is too small to account for the possible phase shift. Apart from the 3.48h
period, which is usually interpreted as the orbital one, we find an additional
period at P=3.78h, which we interpret as the superhump period of the system;
the corresponding precession period at 1.79d is also present in the data. We
also find indications for the presence of a 13min quasi-periodic oscillation.


title:
Non-thermal bremsstrahlung from supernova remnants and the effect of
  Coulomb losses

abstract:
  I investigate the shape of the electron cosmic ray spectrum in the range up
to ~1000 keV, assuming that the acceleration process at the shock results in a
power law in momentum, and that downstream of the shock the spectrum is
affected by Coulomb interactions with background electrons only. In the
non-relativistic regime one can analytically determine the energy of an
electron starting with a certain energy, and use this result to produce an
electron cosmic ray spectrum, modified by Coulomb losses. An analytic
expression for the electron spectrum is obtained that depends on the parameter
n_e t, which can be estimated from a similar parameter used to characterize the
line spectra of supernova remnants. For the brightest supernova remnants n_e t
> 1e11 cm^-3 s,and most of the electrons accelerated to < 100 keV have lost
their energy. Because of its high radio flux, Cas A is the most likely
candidate for non-thermal bremsstrahlung. Although it has n_e t ~ 2e11 cm^-3 s,
one may expect to pick up non-thermal bremsstrahlung above 100 keV with current
hard X-ray detectors.


title: On logarithmic extension of overconvergent isocrystals

abstract:
  In this paper, we establish a criterion for an overconvergent isocrystal on a
smooth variety over a field of characteristic $p>0$ to extend logarithmically
to its smooth compactification whose complement is a strict normal crossing
divisor. This is a generalization of a result of Kedlaya, who treated the case
of unipotent monodromy. Our result is regarded as a $p$-adic analogue of the
theory of canonical extension of regular singular integrable connections on
smooth varieties of characteristic 0.


title:
Gapless spin liquids on the three dimensional hyper-kagome lattice of
  Na$_4$Ir$_3$O$_8$

abstract:
  Recent experiments indicate that Na$_4$Ir$_3$O$_8$, a material in which s=1/2
iridium local moments form a three dimensional network of corner-sharing
triangles, may have a quantum spin liquid ground state with gapless spin
excitations. Using a combination of exact diagonalization, symmetry analysis of
fermionic mean field ground states and Gutzwiller projected variational
wavefunction studies, we propose a quantum spin liquid with spinon Fermi
surfaces as a favorable candidate for the ground state of the Heisenberg model
on the hyper-kagome lattice of Na$_4$Ir$_3$O$_8$. We present a renormalized
mean field theory of the specific heat of this spin liquid and also discuss
possible low temperature instabilities of the spinon Fermi surfaces.


title: Hiding Under the Carpet: a New Strategy for Cloaking

abstract:
  A new type of cloak is discussed: one that gives all cloaked objects the
appearance of a flat conducting sheet. It has the advantage that none of the
parameters of the cloak is singular and can in fact be made isotropic. It makes
broadband cloaking in the optical frequencies one step closer.


title:
Negative differential resistance in molecular junctions: The effect of
  the electrodes electronic structure

abstract:
  We have carried out calculations of electron transport through a
metal-molecule-metal junction with metal nanoclusters taking the part of
electrodes. We show that negative differential resistance peaks could appear in
the current-voltage curves. The peaks arise due to narrow features in the
electron density of states of the metal clusters. The proposed analysis is
based on the ab initio computations of the relevant wave functions and energies
within the framework of the density functional theory using NRLMOL software
package.


title: Parabolic, hyperbolic and elliptic Poincar\'e series

abstract:
  Following Petersson, we study the parabolic, hyperbolic and elliptic
expansions of holomorphic cusp forms and the associated Poincar\'e series. We
show how these ideas extend to the space of second-order cusp forms.


title: Nonsupersymmetric brane vacua in stabilized compactifications

abstract:
  We derive the equations for the nonsupersymmetric vacua of D3-branes in the
presence of nonperturbative moduli stabilization in type IIB flux
compactifications, and solve and analyze them in the case of two particular
7-brane embeddings at the bottom of the warped deformed conifold. In the limit
of large volume and long throat, we obtain vacua by imposing a constraint on
the 7-brane embedding. These vacua fill out continuous spaces of higher
dimension than the corresponding supersymmetric vacua, and have negative
effective cosmological constant. Perturbative stability of these vacua is
possible but not generic. Finally, we argue that anti-D3-branes at the tip of
the conifold share the same vacua as D3-branes.


title: Scanning tunneling microscopy of the 32 K superconductor (Sr1-xKx)Fe2As2

abstract:
  The discovery of high temperature superconductivity in La[O1-xFx]FeAs at the
beginning of this year [1] has generated much excitement and has led to the
rapid discovery of similar compounds with as high as 55 K transition
temperatures [2]. The high superconducting transition temperatures are
seemingly incompatible with the electron-phonon driven pairing of conventional
superconductors, resulting in wide speculation as to the mechanism and nature
of the superconductivity in these materials. Here we report results of the
first scanning tunneling microscopy study of the 32 K superconductor
(Sr1-xKx)Fe2As2. We find two distinct topographic regions on the sample, one
with no apparent atomic corrugation, and another marked by a stripe-like
modulation at double the atomic periodicity. In the latter the stripes appear
to modulate the local density of states, occasionally revealing a Delta = 10 mV
gap with a shape consistent with unconventional (non-s wave) superconductivity.


title: The Semigroup of Betti Diagrams

abstract:
  The recent proof of the Boij-Soederberg conjectures reveals new structure
about Betti diagrams of modules, giving a complete description of the cone of
Betti diagrams. We begin to expand on this new structure by investigating the
semigroup of Betti diagrams. We prove that this semigroup is finitely
generated, and we answer several other fundamental questions about this
semigroup.


title: Debye relaxation in high magnetic fields

abstract:
  Dielectric relaxation is universal in characterizing polar liquids and
solids, insulators, and semiconductors, and the theoretical models are well
developed. However, in high magnetic fields, previously unknown aspects of
dielectric relaxation can be revealed and exploited. Here, we report low
temperature dielectric relaxation measurements in lightly doped silicon in high
dc magnetic fields B both parallel and perpendicular to the applied ac electric
field E. For B//E, we observe a temperature and magnetic field dependent
dielectric dispersion e(w)characteristic of conventional Debye relaxation where
the free carrier concentration is dependent on thermal dopant ionization,
magnetic freeze-out, and/or magnetic localization effects. However, for BperpE,
anomalous dispersion emerges in e(w) with increasing magnetic field. It is
shown that the Debye formalism can be simply extended by adding the Lorentz
force to describe the general response of a dielectric in crossed magnetic and
electric fields. Moreover, we predict and observe a new transverse dielectric
response EH perp B perp E not previously described in magneto-dielectric
measurements. The new formalism allows the determination of the mobility and
the ability to discriminate between magnetic localization/freeze out and
Lorentz force effects in the magneto-dielectric response.


title: Normal Families of Bicomplex Holomorphic Functions

abstract:
  In this article, we introduce the concept of normal families of bicomplex
holomorphic functions to obtain a bicomplex Montel theorem. Moreover, we give a
general definition of Fatou and Julia sets for bicomplex polynomials and we
obtain a characterization of bicomplex Fatou and Julia sets in terms of Fatou
set, Julia set and filled-in Julia set of one complex variable. Some 3D visual
examples of bicomplex Julia sets are also given for the specific slice
$\bold{j}=0$.


title:
Column Subset Selection, Matrix Factorization, and Eigenvalue
  Optimization

abstract:
  Given a fixed matrix, the problem of column subset selection requests a
column submatrix that has favorable spectral properties. Most research from the
algorithms and numerical linear algebra communities focuses on a variant called
rank-revealing {\sf QR}, which seeks a well-conditioned collection of columns
that spans the (numerical) range of the matrix. The functional analysis
literature contains another strand of work on column selection whose
algorithmic implications have not been explored. In particular, a celebrated
result of Bourgain and Tzafriri demonstrates that each matrix with normalized
columns contains a large column submatrix that is exceptionally well
conditioned. Unfortunately, standard proofs of this result cannot be regarded
as algorithmic.
  This paper presents a randomized, polynomial-time algorithm that produces the
submatrix promised by Bourgain and Tzafriri. The method involves random
sampling of columns, followed by a matrix factorization that exposes the
well-conditioned subset of columns. This factorization, which is due to
Grothendieck, is regarded as a central tool in modern functional analysis. The
primary novelty in this work is an algorithm, based on eigenvalue minimization,
for constructing the Grothendieck factorization. These ideas also result in a
novel approximation algorithm for the $(\infty, 1)$ norm of a matrix, which is
generally {\sf NP}-hard to compute exactly. As an added bonus, this work
reveals a surprising connection between matrix factorization and the famous
{\sc maxcut} semidefinite program.


title: Andre-Quillen cohomology of algebras over an operad

abstract:
  We study the Andre-Quillen cohomology with coefficients of an algebra over an
operad. Using resolutions of algebras coming from Koszul duality theory, we
make this cohomology theory explicit and we give a Lie theoretic
interpretation. For which operads is the associated Andre-Quillen cohomology
equal to an Ext-functor ? We give several criterion, based on the cotangent
complex, to characterize this property. We apply it to homotopy algebras, which
gives a new homotopy stable property for algebras over cofibrant operads.


title:
Multi-component measurements of the Jefferson Lab energy recovery linac
  electron beam using optical transition and diffraction radiation

abstract:
  High brightness electron accelerators, such as energy recovery linacs (ERL),
often have complex particle distributions that can create difficulties in beam
transport as well as matching to devices such as wigglers used to generate
radiation from the beam. Optical transition radiation (OTR), OTR interferometry
(OTRI) and optical diffraction-transition radiation interferometry (ODTRI) have
proven to be effective tools for diagnosing both the spatial and angular
distributions of charged particle beams. OTRI and ODTRI have been used to
measure rms divergences and optical transverse phase space mapping has been
demonstrated using OTRI. In this work we present the results of diagnostic
experiments using OTR and ODR conducted at the Jefferson Laboratory 115 MeV ERL
which show the presence of two separate components within the spatial and
angular distributions of the beam. By assuming a correlation between the
spatial and angular features we estimate an rms emittance value for each of the
two components.


title: Radiative Corrections for H1 F2(x,Q**2) Measurement

abstract:
  The numerical study of QED radiative corrections in the low $x$ region for
the H1 experiment at HERA was performed. The analytical program TERAD91 was
used to get the size of the radiative corrections for the measurement of the
proton structure function $F_2(x,Q^2)$ in the range $x= 10^{-2} - 10^{-4}$ and
$ 5 GeV^2 < Q^2 < 80 GeV^2$. It was found that radiative corrections can be not
small in some points of the phase space of the mixed variables.


title: Some New Examples of Non-K\"ahler Ricci Solitons

abstract:
  We produce non-K\"ahler complete steady gradient Ricci solitons generalising
those constructed by Bryant and Ivey.


title: Prospects for the habitability of OGLE-2006-BLG-109L

abstract:
  The extrasolar system OGLE-2006-BLG-109L is the first multiple-planet system
to be discovered by gravitational microlensing (Gaudi et al., 2008); the two
large planets that have been detected have mass ratios, semimajor axis ratios,
and equilibrium temperatures that are similar to those of Jupiter and Saturn;
the mass of the host star is only 0.5 M_sun, and the system is more compact
than our own Solar system. We find that in the habitable zone of the host star,
the two detected planets resonantly excite large orbital eccentricities on a
putative earth-mass planet, driving such a planet out of the habitable zone. We
show that an additional inner planet of ~>0.3M_earth at <~0.1 AU would suppress
the eccentricity perturbation and greatly improve the prospects for
habitability of the system. Thus, the planetary architecture of a potentially
habitable OGLE-2006-BLG-109L planetary system -- with two ``terrestrial''
planets and two jovian planets -- could bear very close resemblance to our own
Solar system.


title: Summing the curious series of Kempner and Irwin

abstract:
  In 1914, Kempner proved that the series 1/1 + 1/2 + ... + 1/8 + 1/10 + 1/11 +
... + 1/18 + 1/20 + 1/21 + ... where the denominators are the positive integers
that do not contain the digit 9, converges to a sum less than 90. The actual
sum is about 22.92068. In 1916, Irwin proved that the sum of 1/n where n has at
most a finite number of 9's is also a convergent series. We show how to compute
sums of Irwins' series to high precision. For example, the sum of the series
1/9 + 1/19 + 1/29 + 1/39 + 1/49 + ... where the denominators have exactly one
9, is about 23.04428708074784831968. Another example: the sum of 1/n where n
has exactly 100 zeros is about 10 ln(10) + 1.007x10^-197 ~ 23.02585; note that
the first, and largest, term in this series is the tiny 1/googol.


title:
Production and decays of the light pseudoscalar boson $\eta$ at the LHC
  in the simplest little Higgs model

abstract:
  In many extensions of the standard model, the Higgs sector often contains an
additional pseudoscalar boson. A good example is the SU(3) simplest little
Higgs model, which accommodates a light pseudoscalar boson $\eta$ with quite
different characteristics from those in other multi-Higgs-doublet models. We
study various phenomenological signatures of the $\eta$ at the LHC. In
particular, we calculate in details both production and decays in the Drell-Yan
type channel $q \bar{q} \to Z/Z' \to h \eta$, and in the associated production
with a $t\bar t$ pair, $gg (q\bar q) \to t \bar t \eta$. We emphasize the
$\tau^+ \tau^-$ decay mode of the $\eta$ boson when its mass is below the
$b\bar b$ threshold. We show that $t\bar t \eta$ production is in fact large
enough to give a sizable number of events while suppressing the backgrounds. We
also comment on the direct gluon fusion process and the indirect decay from the
heavy $T$ quark ($T \to t \eta$)


title:
Recent observation of short range nucleon correlations in nuclei and
  their implications for the structure of nuclei and neutron stars

abstract:
  Novel processes probing the decay of nucleus after removal of a nucleon with
momentum larger than Fermi momentum by hard probes finally proved unambiguously
the evidence for long sought presence of short-range correlations (SRCs) in
nuclei. In combination with the analysis of large $Q^2$, A(e,e')X processes at
$x>1$ they allow us to conclude that (i) practically all nucleons with momenta
$\ge$ 300 MeV/c belong to SRCs, consisting mostly of two nucleons, ii)
probability of such SRCs in medium and heavy nuclei is $\sim 25%$, iii) a fast
removal of such nucleon practically always leads to emission of correlated
nucleon with approximately opposite momentum, iv) proton removal from
two-nucleon SRCs in 90% of cases is accompanied by a removal of a neutron and
only in 10% by a removal of another proton. We explain that observed absolute
probabilities and the isospin structure of two nucleon SRCs confirm the
important role that tensor forces play in internucleon interactions. We find
also that the presence of SRCs requires modifications of the Landau Fermi
liquid approach to highly asymmetric nuclear matter and leads to a
significantly faster cooling of cold neutron stars with neutrino cooling
operational even for $N_p/N_n \le 0.1$. The effect is even stronger for the
hyperon stars. Theoretical challenges raised by the discovered dominance of
nucleon degrees of freedom in SRCs and important role of the spontaneously
broken chiral symmetry in quantum chromodynamics (QCD) in resolving them are
considered. We also outline directions for future theoretical and experimental
studies of the physics relevant for SRCs.


title: Iitaka conjecture $C_{n,m}$ in dimension six

abstract:
  We prove that the Iitaka conjecture $C_{n,m}$ for algebraic fibre spaces
holds up to dimension 6, that is, when $n\le 6$.


title:
$\mu-\tau$ Reflection Symmetry in in Lepton Mixing and Radiatively
  Generated Leptogenesis

abstract:
  We study a $\mu - \tau$ reflection symmetry in neutrino sector realized at
the GUT scale in the context of the seesaw model. In our scenario, the exact
$\mu - \tau$ reflection symmetry realized in the basis where the charged lepton
and heavy Majorana mass matrices are diagonal, leads to vanishing lepton
asymmetries. We find that, in the minimal supersymmetry extension of the seesaw
model with appropriate values of $\tan\beta$, the renormalization group (RG)
evolution from the GUT scale to seesaw scale can induce a successful
leptogenesis. It is shown that the right amount of the baryon asymmetries
$\eta_B$ can be achieved via so-called resonant leptogenesis, which can be
realized at rather low seesaw scale in our scenario, so that the well-known
gravitino problem is safely avoided. In this work, we consider both flavor
dependent and flavor independent leptogenesis, and demonstrate how they lead to
different amounts of baryon asymmetries in detail.


title:
On the inner and outer bounds of 3-receiver broadcast channels with
  2-degraded message sets

abstract:
  We consider a broadcast channel with 3 receivers and 2 messages (M0, M1)
where two of the three receivers need to decode messages (M0, M1) while the
remaining one just needs to decode the message M0. We study the best known
inner and outer bounds under this setting, in an attempt to find the
deficiencies with the current techniques of establishing the bounds. We produce
a simple example where we are able to explicitly evaluate the inner bound and
show that it differs from the general outer bound. For a class of channels
where the general inner and outer bounds differ, we use a new argument to show
that the inner bound is tight.


title:
Topological Identification of Spin-1/2 Two-Leg Ladder with Four-Spin
  Ring Exchange

abstract:
  A spin-1/2 two-leg ladder with four-spin ring exchange is studied by
quantized Berry phases, used as local order parameters. Reflecting local
objects, non-trivial ($\pi$) Berry phase is founded on a rung for the
rung-singlet phase and on a plaquette for the vector-chiral phase. Since the
quantized Berry phase is topological invariant for gapped systems with the time
reversal symmetry, topologically identical models can be obtained by the
adiabatic modification. The rung-singlet phase is adiabatically connected to a
decoupled rung-singlet model and the vector-chiral phase is connected to a
decoupled vector-chiral model. Decoupled models reveals that the local objects
are a local singlet and a plaquette singlet respectively.


title: Gravitational wave detection using multiscale chirplets

abstract:
  A generic `chirp' of the form h(t) = A(t) cos(phi(t)) can be closely
approximated by a connected set of multiscale chirplets with
quadratically-evolving phase. The problem of finding the best approximation to
a given signal using chirplets can be reduced to that of finding the path of
minimum cost in a weighted, directed graph, and can be solved in polynomial
time via dynamic programming. For a signal embedded in noise we apply
constraints on the path length to obtain a statistic for detection of chirping
signals in coloured noise. In this paper we present some results from using
this test to detect binary black hole coalescences in simulated LIGO noise.


title:
Stochastic Wobble of Accretion Discs and Jets from Turbulent Rocket
  Torques

abstract:
  Models of accretion discs and their associated outflows often incorporate
assumptions of axisymmetry and symmetry across the disc plane. However, for
turbulent discs these symmetries only apply to averaged quantities and do not
apply locally. The local asymmetries can induce local imbalances in outflow
power across the disc mid-plane, which can in turn induce local tilting
torques. Here we calculate the effect of the resulting stochastic torques on
disc annuli that are a consequence of standard mean field accretion disc
models. The torques induce a random walk of the vector perpendicular to the
plane of each averaged annulus. This random walk is characterized by a radially
dependent diffusion coefficient which we calculate for small angle tilt. We use
the coefficient to calculate a radially dependent time scale for annular tilt
and associated jet wobble. The wobble time depends on the square of the wander
angle so the age of a given system determines the maximum wobble angle. We
apply this to examples of blazars, young stellar objects and binary engines of
pre-planetary nebulae and microquasars. It is noteworthy that for an averaging
time $t_w\sim 3$ days, we estimate a wobble angle for jets in SS433 of
$\theta\sim 0.8$ degrees, not inconsistent with observational data. In general
the non-periodic nature of the stochastic wobble could distinguish it from
faster periodic jet precession.


title:
Observation and Polarization Measurements of B+- ->phi K_1+- and B+-
  ->phi K_2*+-

abstract:
  With the full $\babar$ data sample of 465 million BaBar pairs, we observe the
decays B+- ->phi(1020) K_1(1270)+- and B+- ->phi(1020) K_2*(1430) +-. We
measure the branching fractions (6.1+-1.6+-1.1)\times 10^{-6} and (8.4+- 1.9+-
0.9)\times 10^{-6} and the fractions of longitudinal polarization
0.46(+0.12-0.13)(+0.03-0.07) and 0.80(+0.09-0.10)+-0.03, respectively. We also
report on the B+- ->phi K_0*(1430)+- decay branching fraction of
(7.0+-1.3+-0.9)\times10^{-6} and several parameters sensitive to CP violation
and interference in the above three decays. Upper limits are placed on the B+-
decay rates to final states with phi and K_1(1400)+-, K*(1410)+-,
K_2(1770)+-,or K_2(1820)+-. Understanding the observed polarization pattern
requires amplitude contributions from an uncertain source.


title:
Nonabelian free group actions: Markov processes, the Abramov-Rohlin
  formula and Yuzvinskii's formula

abstract:
  This paper introduces Markov chains and processes over nonabelian free groups
and semigroups. We prove a formula for the $f$-invariant of a Markov chain over
a free group in terms of transition matrices that parallels the classical
formula for the entropy a Markov chain. Applications include free group
analogues of the Abramov-Rohlin formula for skew-product actions and
Yuzvinskii's addition formula for algebraic actions.


title: Split reductions of simple abelian varieties

abstract:
  Consider an absolutely simple abelian variety X over a number field K. If the
absolute endomorphism ring of X is commutative and satisfies certain parity
conditions, then the reduction X_p is absolutely simple for almost all p.
Conversely, if the absolute endomorphism ring of X is noncommutative, then X_p
is reducible for p in a set of positive density.


title:
Computationally Efficient Estimators for Dimension Reductions Using
  Stable Random Projections

abstract:
  The method of stable random projections is a tool for efficiently computing
the $l_\alpha$ distances using low memory, where $0<\alpha \leq 2$ is a tuning
parameter. The method boils down to a statistical estimation task and various
estimators have been proposed, based on the geometric mean, the harmonic mean,
and the fractional power etc.
  This study proposes the optimal quantile estimator, whose main operation is
selecting, which is considerably less expensive than taking fractional power,
the main operation in previous estimators. Our experiments report that the
optimal quantile estimator is nearly one order of magnitude more
computationally efficient than previous estimators. For large-scale learning
tasks in which storing and computing pairwise distances is a serious
bottleneck, this estimator should be desirable.
  In addition to its computational advantages, the optimal quantile estimator
exhibits nice theoretical properties. It is more accurate than previous
estimators when $\alpha>1$. We derive its theoretical error bounds and
establish the explicit (i.e., no hidden constants) sample complexity bound.


title: On Approximating the Lp Distances for p>2

abstract:
  Applications in machine learning and data mining require computing pairwise
Lp distances in a data matrix A. For massive high-dimensional data, computing
all pairwise distances of A can be infeasible. In fact, even storing A or all
pairwise distances of A in the memory may be also infeasible. This paper
proposes a simple method for p = 2, 4, 6, ... We first decompose the l_p (where
p is even) distances into a sum of 2 marginal norms and p-1 ``inner products''
at different orders. Then we apply normal or sub-Gaussian random projections to
approximate the resultant ``inner products,'' assuming that the marginal norms
can be computed exactly by a linear scan. We propose two strategies for
applying random projections. The basic projection strategy requires only one
projection matrix but it is more difficult to analyze, while the alternative
projection strategy requires p-1 projection matrices but its theoretical
analysis is much easier. In terms of the accuracy, at least for p=4, the basic
strategy is always more accurate than the alternative strategy if the data are
non-negative, which is common in reality.


title:
An Extreme Solar Event of 20 January 2005: Properties of the Flare and
  the Origin of Energetic Particles

abstract:
  The extreme solar and SEP event of 20 January 2005 is analyzed from two
perspectives. Firstly, we study features of the main phase of the flare, when
the strongest emissions from microwaves up to 200 MeV gamma-rays were observed.
Secondly, we relate our results to a long-standing controversy on the origin of
SEPs arriving at Earth, i.e., acceleration in flares, or shocks ahead of CMEs.
All emissions from microwaves up to 2.22 MeV line gamma-rays during the main
flare phase originated within a compact structure located just above sunspot
umbrae. A huge radio burst with a frequency maximum at 30 GHz was observed,
indicating the presence of a large number of energetic electrons in strong
magnetic fields. Thus, protons and electrons responsible for flare emissions
during its main phase were accelerated within the magnetic field of the active
region. The leading, impulsive parts of the GLE, and highest-energy gamma-rays
identified with pi^0-decay emission, are similar and correspond in time. The
origin of the pi^0-decay gamma-rays is argued to be the same as that of lower
energy emissions. We estimate the sky-plane speed of the CME to be 2000-2600
km/s, i.e., high, but of the same order as preceding non-GLE-related CMEs from
the same active region. Hence, the flare itself rather than the CME appears to
determine the extreme nature of this event. We conclude that the acceleration,
at least, to sub-relativistic energies, of electrons and protons, responsible
for both the flare emissions and the leading spike of SEP/GLE by 07 UT, are
likely to have occurred simultaneously within the flare region. We do not rule
out a probable contribution from particles accelerated in the CME-driven shock
for the leading GLE spike, which seemed to dominate later on.


title: On the Geodesic Nature of Wegner's Flow

abstract:
  Wegner's method of flow equations offers a useful tool for diagonalizing a
given Hamiltonian and is widely used in various branches of quantum physics.
Here, generalizing this method, a condition is derived, under which the
corresponding flow of a quantum state becomes geodesic in a submanifold of the
projective Hilbert space, independently of specific initial conditions. This
implies the geometric optimality of the present method as an algorithm of
generating stationary states. The result is illustrated by analyzing some
physical examples.

categories: quant-ph cond-mat.other nucl-th physics.atom-ph


title: On the generalization of Gurland distribution

abstract:
  In the present paper a generalization of Gurland distribution [3] is obtained
as a beta mixture of the generalized Poisson distribution (GPD) of Consul and
Jain [2]. The first two moments of the distribution and a recurrence relation
among probabilities are obtained. The present distribution is supposed to be
more general in nature and wider in scope.


title: Giant Nernst Effect due to Fluctuating Cooper Pairs in Superconductors

abstract:
  A theory of the fluctuation-induced Nernst effect is developed for arbitrary
magnetic fields and temperatures beyond the upper critical field line in a
two-dimensional superconductor. First, we derive a simple phenomenological
formula for the Nernst coefficient, which naturally explains the giant Nernst
signal due to fluctuating Cooper pairs. The latter is shown to be large even
far from the transition and may exceed by orders of magnitude the Fermi liquid
terms. We also present a complete microscopic calculation (which includes
quantum fluctuations) of the Nernst coefficient and give its asymptotic
dependencies in various regions on the phase diagram. It is argued that the
magnitude and the behavior of the Nernst signal observed experimentally in
disordered superconducting films can be well-understood on the basis of the
superconducting fluctuation theory.


title: Topology and Collapse

abstract:
  We show that the collapse of the wave function of an entangled state of two
spin 1/2 particles or two photons in the singlet state can be geometrically
understood as a change of fibre bundles.


title: Quantum Mechanics and Leggett's Inequalities

abstract:
  We show that when the proper description of the behaviour of individual
photons or spin 1/2 particles in a spherically symmetric entangled pair is done
through the use of the density matrix, the Leggett's inequality is not violated
by quantum mechanics.


title: Non-adiabatic effect on Laughlin's argument of the quantum Hall effect

abstract:
  We have numerically studied a non-adiabatic charge transport in the quantum
Hall system pumped by a magnetic flux, as one of the simplest theoretical
realizations of non-adiabatic Thouless pumping. In the adiabatic limit, a
pumped charge is quantized, known as Laughlin's argument in a cylindrical
lattice. In a uniform electric field, we obtained a formula connecting
quantized pumping in the adiabatic limit and no-pumping in the sudden limit.
The intermediate region between the two limits is determined by the Landau gap.
A randomness or impurity effect is also discussed.


title:
Dephasing in two decoupled one-dimensional Bose-Einstein condensates and
  the subexponential decay of the interwell coherence

abstract:
  We provide a simple physical picture of the loss of coherence between two
coherently split one-dimensional Bose-Einstein condensates. The source of the
dephasing is identified with nonlinear corrections to the elementary excitation
energies in either of the two independent condensates. We retrieve the result
by Burkov, Lukin and Demler [Phys. Rev. Lett. 98, 200404 (2007)] on the
subexponential decay of the cocherence for the large time, however, the scaling
of the characteristic decoherence time differs.


title:
Observation of Spin Fluctuations in a High-Tc Parent Compound Using
  Resonant Inelastic X-ray Scattering

abstract:
  We report the first observation of soft-x-ray scattering from spin
fluctuations in a high-Tc parent compound. An antiferromagnetic charge transfer
insulator, CaCuO2, was irradiated by Cu M-edge soft x-rays. Ultra-high
resolution measurements of scattered intensity revealed magnon-magnon
excitations, due to spin exchange scattering, as low-energy loss features. The
process is analogous to optical Raman scattering. The spectra provide the first
measurement of the two-magnon excitation energy and the antiferromagnetic
exchange parameter in infinite-layer CaCuO2. The results reveal resonant
inelastic soft x-ray scattering as a novel probe of the spin dynamics in
cuprates.


title: On endomorphism rings and dimensions of local cohomology modules

abstract:
  Let $(R,\mathfrak m)$ denote an $n$-dimensional complete local Gorenstein
ring. For an ideal $I$ of $R$ let $H^i_I(R), i \in \mathbb Z,$ denote the local
cohomology modules of $R$ with respect to $I.$ If $H^i_I(R) = 0$ for all $i
\not= c = \height I,$ then the endomorphism ring of $H^c_I(R)$ is isomorphic to
$R$ (cf. \cite{HSt} and \cite{HS}). Here we prove that this is true if and only
if $H^i_I(R) = 0, i = n, n -1$ provided $c \geq 2$ and $R/I$ has an isolated
singularity resp. if $I$ is set-theoretically a complete intersection in
codimension at most one. Moreover, there is a vanishing result of $H^i_I(R)$
for all $i > m, m$ a given integer, resp. an estimate of the dimension of
$H^i_I(R).$


title: Nonminimal coupling of perfect fluids to curvature

abstract:
  In this work, we consider different forms of relativistic perfect fluid
Lagrangian densities, that yield the same gravitational field equations in
General Relativity. A particularly intriguing example is the case with
couplings of the form $[1+f_2(R)]{\cal L}_m$, where $R$ is the scalar
curvature, which induces an extra force that depends on the form of the
Lagrangian density. It has been found that, considering the Lagrangian density
${\cal L}_m = p$, where $p$ is the pressure, the extra-force vanishes. We argue
that this is not the unique choice for the matter Lagrangian density, and that
more natural forms for ${\cal L}_m$ do not imply the vanishing of the
extra-force. Particular attention is paid to the impact on the classical
equivalence between different Lagrangian descriptions of a perfect fluid.


title: Reconstructing a String-Inspired Quintom Model of Dark Energy

abstract:
  In this paper, we develop a simple method for the reconstruction of the
string-inspired dark energy model with the lagrangian $ {\cal L} = -V (\phi)
\sqrt{1 - \alpha' {\nabla}_{\mu} \phi \nabla^{\mu} \phi + \beta' \phi \Box
\phi} $ given by Cai et. al., which may allow the equation-of-state parameter
cross the cosmological constant boundary $ (w=-1) $. We reconstruct this model
in the light of three forms of parametrization for dynamical dark energy.