title: Thermal dileptons in high-energy nuclear collisions

abstract:
  Clear signs of excess dileptons above the known sources were found at the SPS
since long. However, a real clarification of these observations was only
recently achieved by NA60, measuring dimuons with unprecedented precision in
158A GeV In-In collisions. The excess mass spectrum in the region M<1 GeV is
consistent with a dominant contribution from pi+pi- -> rho -> mu+mu-
annihilation. The associated rho spectral function shows a strong broadening,
but essentially no shift in mass. In the region M>1 GeV, the excess is found to
be prompt, not due to enhanced charm production. The inverse slope parameter
Teff associated with the transverse momentum spectra rises with mass up to the
rho, followed by a sudden decline above. While the initial rise, coupled to a
hierarchy in hadron freeze-out, points to radial flow of a hadronic decay
source, the decline above signals a transition to a low-flow source, presumably
of partonic origin. The mass spectra show the steep rise towards low masses
characteristic for Planck-like radiation. The polarization of the excess
referred to the Collins Soper frame is found to be isotropic. All observations
are consistent with a global interpretation of the excess as thermal radiation.
We conclude with a short discussion of a possible link to direct photons.


title:
Patching and local-global principles for homogeneous spaces over
  function fields of p-adic curves

abstract: This is the final version, to appear in Commentarii Mathematici Helvetici.


title:
First results on angular distributions of thermal dileptons in nuclear
  collisions

abstract:
  The NA60 experiment at the CERN SPS has studied dimuon production in 158A GeV
In-In collisions. The strong excess of pairs above the known sources found in
the complete mass region 0.2<M<2.6 GeV has previously been interpreted as
thermal radiation. We now present first results on the associated angular
distributions. Using the Collins-Soper reference frame, the structure function
parameters \lambda, \mu and \nu are measured to be zero, and the projected
distributions in polar and azimuth angles are found to be uniform. The absence
of any polarization is consistent with the interpretation of the excess dimuons
as thermal radiation from a randomized system.


title:
The structure of a local embedding and applications to Chern classes of
  weighted blow-ups

abstract:
  For a proper local embedding between two Deligne--Mumford stacks Y and X, we
find, under certain mild conditions, a new (possibly non-separated)
Deligne--Mumford stack X', with an etale, surjective and universally closed map
to the target X, and whose fiber product with the image of the local embedding
is a finite union of stacks with corresponding etale, surjective and
universally closed maps to Y. Moreover, a natural set of weights on the
substacks of X' allows the construction of a universally closed push-forward,
and thus a comparison between the Chow groups of X' and X. We apply the
construction above to the computation of the Chern classes of a weighted
blow-up along a regular local embedding via deformation to a weighted normal
cone and localization. We describe the stack X' in the case when X is the
moduli space of stable maps with local embeddings at the boundary. We apply the
methods above to find the Chern classes of the stable map spaces.


title: Parameter estimation for rough differential equations

abstract:
  We construct the "expected signature matching" estimator for differential
equations driven by rough paths and we prove its consistency and asymptotic
normality. We use it to estimate parameters of a diffusion and a fractional
diffusions, that is, a differential equation driven by fractional Brownian
motion.


title: Fluorine in AGB Carbon Stars Revisited

abstract:
  A reanalysis of the fluorine abundance in three Galactic AGB carbon stars (TX
Psc, AQ Sgr and R Scl) has been performed from the molecular HF (1-0) R9 line
at 2.3358 $\mu$m. High-resolution (R$\sim 50000$) and high signal to noise
spectra obtained with the CRIRES spectrograph and the VLT telescope or from the
NOAO archive (for TX Psc) have been used. Our abundance analysis uses the
latest generation of MARCS model atmospheres for cool carbon rich stars. Using
spectral synthesis in LTE we derive for these stars fluorine abundances that
are systematically lower by $\sim 0.8$ dex in average with respect to the sole
previous estimates by Jorissen, Smith & Lambert (1992). The possible reasons of
this discrepancy are explored. We conclude that the difference may rely on the
blending with C-bearing molecules (CN and C$_2$) that were not properly taken
into account in the former study. The new F abundances are in better agreement
with the prediction of full network stellar models of low mass AGB stars. These
models also reproduce the $s$-process elements distribution in the sampled
stars. This result, if confirmed in a larger sample of AGB stars, might
alleviate the current difficulty to explain the largest [F/O] ratios found by
Jorissen et al. In particular, it may not be necessary to search for
alternative nuclear chains affecting the production of F in AGB stars.


title:
Construction of potential systems for systems of PDEs with
  multi-dimensional spaces of conservation laws

abstract:
  In this paper we consider generalization of procedure of construction of
potential systems for systems of partial differential equations with
multidimensional spaces of conservation laws. More precisely, for construction
of potential systems in cases when dimension of the space of local conservation
laws is greater than one, instead of using only basis conservation laws we use
their arbitrary linear combinations being inequivalent with respect to
equivalence group of the class of systems or symmetry group of the fixed
system. It appears that the basis conservation laws can be equivalent with
respect to groups of symmetry or equivalence transformations, or vice versa,
the number of independent in this sense linear combinations of conservation
laws can be grater than the dimension of the space of conservation laws. The
first possibility leads to an unnecessary, often cumbersome, investigation of
equivalent systems, the second one makes possible missing a great number of
inequivalent potential systems. Examples of all these possibilities are given.


title: Orders of Finite Reductive Monoids

abstract:
  We show four formulas for calculating the orders of finite reductive monoids
with zero. As applications, these formulas are then used to calculate the
orders of finite reductive monoids induced from the $F_q$-split
$\J$-irreducible monoids $\overline {K^*\rho(G_0)}$ where $G_0$ is a simple
algebraic group over the algebraic closure of $F_q$, and $\rho: G_0\to GL(V)$
is the irreducible representation associated with any dominant weight. Finally,
we give an explicit formula for the orders of finite symplectic monoids
associated with the last fundamental dominant weight of type $C_l$; the
connections to $H$-polynomials and Betti numbers are shown.


title:
Turbulent dynamos in spherical shell segments of varying geometrical
  extent

abstract:
  We use three-dimensional direct numerical simulations of the helically forced
magnetohydrodynamic equations in spherical shell segments in order to study the
effects of changes in the geometrical shape and size of the domain on the
growth and saturation of large-scale magnetic fields. We inject kinetic energy
along with kinetic helicity in spherical domains via helical forcing using
Chandrasekhar-Kendall functions. We take perfect conductor boundary conditions
for the magnetic field to ensure that no magnetic helicity escapes the domain
boundaries. We find dynamo action giving rise to magnetic fields at scales
larger than the characteristic scale of the forcing. The magnetic energy
exceeds the kinetic energy over dissipative time scales, similar to that seen
earlier in Cartesian simulations in periodic boxes. As we increase the size of
the domain in the azimuthal direction we find that the nonlinearly saturated
magnetic field organizes itself in long-lived cellular structures with aspect
ratios close to unity. These structures tile the domain along the azimuthal
direction, thus resulting in very small longitudinally averaged magnetic fields
for large domain sizes. The scales of these structures are determined by the
smallest scales of the domain, which in our simulations is usually the radial
scale. We also find that increasing the meridional extent of the domains
produces little qualitative change, except a marginal increase in the
large-scale field. We obtain qualitatively similar results in Cartesian domains
with similar aspect ratios.


title:
Two-parameter Quantum Affine Algebra $U_{r,s}(\widehat{\frak {sl}_n})$,
  Drinfel'd Realization and Quantum Affine Lyndon Basis

abstract:
  We further define two-parameter quantum affine algebra
$U_{r,s}(\widehat{\frak {sl}_n})$ $(n>2)$ after the work on the finite cases
(see [BW1], [BGH1], [HS] & [BH]), which turns out to be a Drinfel'd double. Of
importance for the quantum {\it affine} cases is that we can work out the
compatible two-parameter version of the Drinfel'd realization as a quantum
affinization of $U_{r,s}(\frak{sl}_n)$ and establish the Drinfel'd isomorphism
Theorem in the two-parameter setting, via developing a new combinatorial
approach (quantum calculation) to the quantum {\it affine} Lyndon basis we
present (with an explicit valid algorithm based on the use of Drinfel'd
generators).


title: Differential equations from null vectors of the Ramond algebra

abstract:
  We consider chiral blocks of four Ramond fields of the N=1 super Virasoro
algebra where one of the fields is in the (1,2) representation. We show how the
null vector in the (1,2) representation determines the chiral blocks as series
expansions. We then turn to the Ising model to find an algebraic method to
determine differential equations for the blocks of four spin fields. Extending
these ideas to the super Virasoro case, we find a first order differential
equation for blocks of four Ramond fields. We are able to find exact solutions
in many cases. We compare our blocks with results known from other methods.


title:
Quantitative approach to facilitated diffusion with intersegmental
  jumping

abstract:
  We study the impact of DNA coiling on the search rate of proteins moving
along the DNA contour interspersed by three-dimensional (3D) bulk excursions.
When the DNA is coiled proteins performing short 3D hops along a DNA segment
can be captured by foreign DNA segments that have looped back close to the
original segment. These intersegmental jumps are shown to enhance the search
rate for a specific site on the DNA by lowering the tendency to resample
previously visited sites on the DNA. The model developed here offers a
quantitative description of recent single molecule experiments on facilitated
diffusion of restriction enzymes EcoRV.


title: QCD with rooted staggered fermions

abstract:
  In this talk, I will give an overview of the theoretical status of staggered
Lattice QCD with the "fourth-root trick." In this regularization of QCD, a
separate staggered quark field is used for each physical flavor, and the
inherent four-fold multiplicity that comes with the use of staggered fermions
is removed by taking the fourth root of the staggered determinant for each
flavor. At nonzero lattice spacing, the resulting theory is nonlocal and not
unitary, but there are now strong arguments that this disease is cured in the
continuum limit. In addition, the approach to the continuum limit can be
understood in detail in the framework of effective field theories such as
staggered chiral perturbation theory.


title: Designing and understanding directional emission from spiral microlasers

abstract:
  The availability of microlasers with highly directional far-field
characteristics is crucial for future applications. To this end we study the
far-field emission of active microcavities with spiral shape using the
Schroedinger-Bloch model. We find that they can provide directional emission
under the conditions of (i) pumping along the resonator boundary and (ii) for
specific resonator geometries. We systematically study the far-field
characteristics under variation of the pumped area and the cavity geometry, and
identify an directionality-optimized regime. Our results consistently explain
previously obtained experimental results.


title: Hydrodynamics of superfluids confined in blocked rings and wedges

abstract:
  Motivated by many recent experimental studies of non-classical rotational
inertia (NCRI) in superfluid and supersolid samples, we present a study of the
hydrodynamics of a superfluid confined in the two-dimensional region
(equivalent to a long cylinder) between two concentric arcs of radii $b$ and
$a$ ($b<a$) subtending an angle $\beta$, with $0 \le \beta \le 2\pi$. The case
$\beta= 2 \pi$ corresponds to a blocked ring. We discuss the methodology to
compute the NCRI effects, and calculate these effects both for small angular
velocities, when no vortices are present, and in the presence of a vortex. We
find that, for a blocked ring, the NCRI effect is small, and that therefore
there will be a large discontinuity in the moment of inertia associated with
blocking or unblocking circular paths. For blocked wedges ($b=0$) with $\beta >
\pi$, we find an unexpected divergence of the velocity at the origin, which
implies the presence of either a region of normal fluid or a vortex for {\it
any} nonzero value of the angular velocity. Implications of our results for
experiments on "supersolid" behavior in solid $^4{\rm He}$ are discussed. A
number of mathematical issues are pointed out and resolved.


title: Critical Value of the Quantum Ising Model on Star-Like Graphs

abstract:
  We present a rigorous determination of the critical value of the ground-state
quantum Ising model in a transverse field, on a class of planar graphs which we
call star-like. These include the star graph, which is a junction of several
copies of Z at a single point. Our approach is to use the graphical, or FK-,
representation of the model, and the probabilistic and geometric tools
associated with it.

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


title: Estimate of the systematic error in tau decay due to duality violations

abstract:
  With the help of a physically motivated ansatz, which is fitted to the data,
we estimate the size of possible duality violations in hadronic tau decay. The
result is that the uncertainty associated with these violations could impact
the alpha_s determination from the total decay width at a level which we
estimate to be \delta alpha_s(m_tau) \sim 0.003-0.010. Consequently, it cannot
be neglected.


title: Accurate numerical linear algebra with Bernstein-Vandermonde matrices

abstract:
  The accurate solution of some of the main problems in numerical linear
algebra (linear system solving, eigenvalue computation, singular value
computation and the least squares problem) for a totally positive
Bernstein-Vandermonde matrix is considered. Bernstein-Vandermonde matrices are
a generalization of Vandermonde matrices arising when considering for the space
of the algebraic polynomials of degree less than or equal to $n$ the Bernstein
basis, a widely used basis in Computer Aided Geometric Design, instead of the
monomial basis.
  Our approach is based on the computation of the bidiagonal factorization of a
totally positive Bernstein-Vandermonde matrix (or its inverse) by means of
Neville elimination. The explicit expressions obtained for the determinants
involved in the process makes the algorithm both fast and accurate.


title: Accurate computations with Said-Ball-Vandermonde matrices

abstract:
  A generalization of the Vandermonde matrices which arise when the power basis
is replaced by the Said-Ball basis is considered. When the nodes are inside the
interval (0,1), then those matrices are strictly totally positive. An algorithm
for computing the bidiagonal decomposition of those Said-Ball-Vandermonde
matrices is presented, which allows to use known algorithms for totally
positive matrices represented by their bidiagonal decomposition. The algorithm
is shown to be fast and to guarantee high relative accuracy. Some numerical
experiments which illustrate the good behaviour of the algorithm are included.


title:
Pricing and hedging barrier options in a hyper-exponential additive
  model

abstract:
  In this paper we develop an algorithm to calculate the prices and Greeks of
barrier options in a hyper-exponential additive model with piecewise constant
parameters. We obtain an explicit semi-analytical expression for the
first-passage probability. The solution rests on a randomization and an
explicit matrix Wiener-Hopf factorization. Employing this result we derive
explicit expressions for the Laplace-Fourier transforms of the prices and
Greeks of barrier options. As a numerical illustration, the prices and Greeks
of down-and-in digital and down-and-in call options are calculated for a set of
parameters obtained by a simultaneous calibration to Stoxx50E call options
across strikes and four different maturities. By comparing the results with
Monte-Carlo simulations, we show that the method is fast, accurate, and stable.


title:
Correlation function of spectral staircase and particle number
  fluctuations in integrable systems

abstract:
  We evaluate the correlation function of the spectral staircase and use it to
evaluate the mesoscopic particle number fluctuations in integrable systems.

categories: cond-mat.mes-hall cond-mat.stat-mech nlin.CD quant-ph


title:
On the Diversity of Gauge Mediation: Footprints of Dynamical SUSY
  Breaking

abstract:
  Recent progress in realising dynamical supersymmetry breaking allows the
construction of simple and calculable models of gauge mediation. We discuss the
phenomenology of the particularly minimal case in which the mediation is
direct, and show that there are generic new and striking predictions. These
include new particles with masses comparable to those of the Standard Model
superpartners, associated with the pseudo-Goldstone modes of the dynamical SUSY
breaking sector. Consequently there is an unavoidable departure from the MSSM.
In addition the gaugino masses are typically significantly lighter than the
sfermions, and their mass ratios can be different from the pattern dictated by
the gauge couplings in standard (i.e. explicit) gauge mediation. We investigate
these features in two distinct realisations of the dynamical SUSY breaking
sector.


title:
Mode Switching for MIMO Broadcast Channel Based on Delay and Channel
  Quantization

abstract:
  Imperfect channel state information degrades the performance of
multiple-input multiple-output (MIMO) communications; its effect on single-user
(SU) and multi-user (MU) MIMO transmissions are quite different. In particular,
MU-MIMO suffers from residual inter-user interference due to imperfect channel
state information while SU-MIMO only suffers from a power loss. This paper
compares the throughput loss of both SU and MU MIMO on the downlink due to
delay and channel quantization. Accurate closed-form approximations are derived
for the achievable rates for both SU and MU MIMO. It is shown that SU-MIMO is
relatively robust to delayed and quantized channel information, while MU MIMO
with zero-forcing precoding loses spatial multiplexing gain with a fixed delay
or fixed codebook size. Based on derived achievable rates, a mode switching
algorithm is proposed that switches between SU and MU MIMO modes to improve the
spectral efficiency, based on the average signal-to-noise ratio (SNR), the
normalized Doppler frequency, and the channel quantization codebook size. The
operating regions for SU and MU modes with different delays and codebook sizes
are determined, which can be used to select the preferred mode. It is shown
that the MU mode is active only when the normalized Doppler frequency is very
small and the codebook size is large.


title:
Finite-Temperature Behavior of an Inter-species Fermionic Superfluid
  with Population Imbalance

abstract:
  We determine the superfluid transition temperature $T_c$ and related finite
temperature phase diagrams for the entire BCS-Bose Einstein condensation
crossover in a homogeneous mixture of $^{6}$Li and $^{40}$K atoms with
population imbalance. Our work is motivated by the recent observation of an
inter-species Feshbach resonance. Pairing fluctuation effects, which
significantly reduce $T_c$ from the onset temperature for pairing ($T^*$),
provide reasonable estimates of $T_c$ and indicate that the inter-species
superfluid phase should be accessible in future experiments. Although a
generalized-Sarma phase is not stable in the ground state near unitarity, our
phase diagrams show that it appears as an intermediate-temperature superfluid.

categories: cond-mat.other cond-mat.quant-gas cond-mat.str-el cond-mat.supr-con


title: Cosmological constraints on unifying Dark Fluid models

abstract:
  In the standard model of cosmology, dark matter and dark energy are presently
the two main contributors to the total energy in the Universe. However, these
two dark components are still of unknown nature, and many alternative
explanations are possible. We consider here the so-called unifying dark fluid
models, which replace dark energy and dark matter by a unique dark fluid with
specific properties. We will analyze in this context recent observational data
from supernovae of type Ia, large scale structures and cosmic microwave
background, as well as theoretical results of big-bang nucleosynthesis, in
order to derive constraints on the dark fluid parameters. We will also consider
constraints from local scales, and conclude with a brief study of a scalar
field dark fluid model.


title: ALICE diffractive physics in p-p and Pb-Pb collisions at the LHC

abstract:
  The ALICE detector is introduced and a double gap trigger is presented. The
interest in studying double pomeron induced events both in proton-proton and in
lead-lead reactions is discussed.


title:
Achievable Throughput of Multi-mode Multiuser MIMO with Imperfect CSI
  Constraints

abstract:
  For the multiple-input multiple-output (MIMO) broadcast channel with
imperfect channel state information (CSI), neither the capacity nor the optimal
transmission technique have been fully discovered. In this paper, we derive
achievable ergodic rates for a MIMO fading broadcast channel when CSI is
delayed and quantized. It is shown that we should not support too many users
with spatial division multiplexing due to the residual inter-user interference
caused by imperfect CSI. Based on the derived achievable rates, we propose a
multi-mode transmission strategy to maximize the throughput, which adaptively
adjusts the number of active users based on the channel statistics information.


title: Deeply virtual Compton scattering and generalized parton distributions

abstract:
  We present a comparison of a recently proposed model, which describes the
Deeply Virtual Compton Scattering amplitude, to the HERA data.


title: Mutual Orbits and Masses of Six Transneptunian Binaries

abstract:
  We present Hubble Space Telescope observations of six binary transneptunian
systems: 2000 QL251, 2003 TJ58, 2001 XR254, 1999 OJ4, (134860) 2000 OJ67, and
2004 PB108. The mutual orbits of these systems are found to have periods
ranging from 22 to 137 days, semimajor axes ranging from 2360 to 10500 km, and
eccentricities ranging from 0.09 to 0.55. These orbital parameters enable
estimation of system masses ranging from 0.2 to 9.7 x 10+18 kg. For reasonable
assumptions of bulk density (0.5 to 2.0 g cm-3), the masses can be combined
with visible photometry to constrain sizes and albedos. The resulting albedos
are consistent with an emerging picture of the dynamically "Cold" Classical
subpopulation having relatively high albedos, compared with comparablysized
objects on more dynamically excited orbits.


title:
On Superspace Actions for Multiple M2-Branes, Metric 3-Algebras and
  their Classification

abstract:
  We classify canonical metric 3-algebra structures on matrix algebras and find
novel three-dimensional conformally invariant actions in N=4 projective
superspace based on them. These can be viewed as Chern-Simons theories with
special matter content and couplings. We explore the relations of these actions
with the N=2 actions based on generalized 3-Lie algebras found earlier and
relate them to the original Bagger-Lambert-Gustavsson action.


title:
A transform approach to compute prices and greeks of barrier options
  driven by a class of Levy processes

abstract:
  In this paper we propose a transform method to compute the prices and greeks
of barrier options driven by a class of Levy processes. We derive analytical
expressions for the Laplace transforms in time of the prices and sensitivities
of single barrier options in an exponential Levy model with hyper-exponential
jumps. Inversion of these single Laplace transform yields rapid, accurate
results. These results are employed to construct an approximation of the prices
and sensitivities of barrier options in exponential generalised
hyper-exponential (GHE) Levy models. The latter class includes many of the Levy
models employed in quantitative finance such as the variance gamma (VG), KoBoL,
generalised hyperbolic, and the normal inverse Gaussian (NIG) models.
Convergence of the approximating prices and sensitivities is proved. To provide
a numerical illustration, this transform approach is compared with Monte Carlo
simulation in the cases that the driving process is a VG and a NIG Levy
process. Parameters are calibrated to Stoxx50E call options.


title: Mass corrections in string theory and lattice field theory

abstract:
  Kaluza-Klein compactifications of higher dimensional Yang-Mills theories
contain a number of four dimensional scalars corresponding to the internal
components of the gauge field. While at tree-level the scalar zero modes are
massless, it is well known that quantum corrections make them massive. We
compute these radiative corrections at 1-loop in an effective field theory
framework, using the background field method and proper Schwinger-time
regularization. In order to clarify the proper treatment of the sum over
KK--modes in the effective field theory approach, we consider the same problem
in two different UV completions of Yang-Mills: string theory and lattice field
theory. In both cases, when the compactification radius $R$ is much bigger than
the scale of the UV completion ($R \gg \sqrt{\alpha'},a$), we recover a mass
renormalization that is independent of the UV scale and agrees with the one
derived in the effective field theory approach. These results support the idea
that the value of the mass corrections is, in this regime, universal for any UV
completion that respects locality and gauge invariance. The string analysis
suggests that this property holds also at higher loops. The lattice analysis
suggests that the mass of the adjoint scalars appearing in $\mathcal N=2,4$
Super Yang-Mills is highly suppressed due to an interplay between the
higher-dimensional gauge invariance and the degeneracy of bosonic and fermionic
degrees of freedom.


title:
The Peculiar Shape of the Beta_(app)-z Distribution Seen in Radio Loud
  AGN Jets Is Explained Simply and Naturally In the Local Quasar Model

abstract:
  Recently, it was argued that the log(z)-m_{v} plot of 106,000 AGN galaxies
could be interpreted as an evolutionary path followed by local AGN galaxies as
they age. It was suggested that these objects are born as quasars with a high
intrinsic redshift component that decreases with time. When the intrinsic
component is large it causes them to be pushed above the standard candle line
for brightest radio galaxies on a log(z)-m_{v} plot. In the jets of radio loud
AGN galaxies, Beta_(app) is the apparent transverse velocity of the ejected
material relative to the speed of light. In the cosmological redshift (CR)
model the Beta_(app) vs z distribution has a peculiar shape, and there have
been several attempts to explain it. In agreement with the model proposed to
explain the log(z)-m_{v} plot, it is shown here that the peculiar shape of the
Beta_(app)-z distribution in the CR model is exactly what is expected if the
sources are local but their large intrinsic redshifts are assumed to be
cosmological in the calculation of Beta_(app). This result not only supports
our previous interpretation of the log(z)-m_{v} plot, it further implies that
if a large component of the redshift is intrinsic a similar effect should be
visible when other parameters are plotted vs z. Examining this it is also found
that the results are consistent with the local model.


title:
Landau-De Gennes theory of nematic liquid crystals: the Oseen-Frank
  limit and beyond

abstract:
  We study global minimizers of a continuum Landau-De Gennes energy functional
for nematic liquid crystals, in three-dimensional domains, subject to uniaxial
boundary conditions. We analyze the physically relevant limit of small elastic
constant and show that global minimizers converge strongly, in $W^{1,2}$, to a
global minimizer predicted by the Oseen-Frank theory for uniaxial nematic
liquid crystals with constant order parameter. Moreover, the convergence is
uniform in the interior of the domain, away from the singularities of the
limiting Oseen-Frank global minimizer. We obtain results on the rate of
convergence of the eigenvalues and the regularity of the eigenvectors of the
Landau-De Gennes global minimizer.
  We also study the interplay between biaxiality and uniaxiality in Landau-De
Gennes global energy minimizers and obtain estimates for various related
quantities such as the biaxiality parameter and the size of admissible strongly
biaxial regions.


title:
Reducing spurious gravitational radiation in binary-black-hole
  simulations by using conformally curved initial data

abstract:
  At early times in numerical evolutions of binary black holes, current
simulations contain an initial burst of spurious gravitational radiation (also
called "junk radiation") which is not astrophysically realistic. The spurious
radiation is a consequence of how the binary-black-hole initial data are
constructed: the initial data are typically assumed to be conformally flat. In
this paper, I adopt a curved conformal metric that is a superposition of two
boosted, non-spinning black holes that are approximately 15 orbits from merger.
I compare junk radiation of the superposed-boosted-Schwarzschild (SBS) initial
data with the junk of corresponding conformally flat, maximally sliced (CFMS)
initial data. The SBS junk is smaller in amplitude than the CFMS junk, with the
junk's leading-order spectral modes typically being reduced by a factor of
order two or more.


title:
Constant Mean Curvature Hypersurfaces Condensing to Geodesic Segments
  and Rays in Riemannian Manifolds

abstract:
  We construct examples of compact and one-ended constant mean curvature
surfaces with large mean curvature in Riemannian manifolds with axial symmetry
by gluing together small spheres positioned end-to-end along a geodesic. Such
surfaces cannot exist in Euclidean space, but we show that the gradient of the
ambient scalar curvature acts as a `friction term' which permits the usual
analytic gluing construction to be carried out.


title:
Equivalence between supersymmetric self-dual and Maxwell-Chern-Simons
  models coupled to a matter spinor superfield

abstract:
  We study the duality of the supersymmetric self-dual and Maxwell-Chern-Simons
theories coupled to a fermionic matter superfield, using a master action. This
approach evades the difficulties inherent to the quartic couplings that appear
when matter is represented by a scalar superfield. The price is that the
spinorial matter superfield represents a unusual supersymmetric multiplet,
whose main physical properties we also discuss.


title: Model Discrimination at the LHC: a Case Study

abstract:
  We investigate the potential of the Compact Muon Solenoid (CMS) detector at
the Large Hadron Collider (LHC) to discriminate between two theoretical models
predicting anomalous events with jets and large missing transverse energy,
minimal supersymmetry and Little Higgs with T Parity. We focus on a simple test
case scenario, in which the only exotic particles produced at the LHC are heavy
color-triplet states (squarks or T-quarks), and the only open decay channel for
these particles is into the stable missing-energy particle (neutralino or heavy
photon) plus a quark. We find that in this scenario, the angular and momentum
distributions of the observed jets are sufficient to discriminate between the
two models with a few inverse fb of the LHC data, provided that these
distributions for both models and the dominant Standard Model backgrounds can
be reliably predicted by Monte Carlo simulations.


title: Visualizing changes in student responses using consistency plots

abstract:
  Traditional methods of reporting changes in student responses have focused on
class-wide averages. Such models hide information about the switches in
responses by individual students over the course of a semester. We extend
unpublished work by Steven Kanim on "escalator diagrams" which show changes in
student responses from correct to incorrect (and vice versa) while representing
pre- and post-instruction results on questions. Our extension consists of
"consistency plots" in which we represent three forms of data: method of
solution and correctness of solution both before and after instruction. Our
data are from an intermediate mechanics class, and come from (nearly) identical
midterm and final examination questions.


title: Compressive sensing: a paradigm shift in signal processing

abstract:
  We survey a new paradigm in signal processing known as "compressive sensing".
Contrary to old practices of data acquisition and reconstruction based on the
Shannon-Nyquist sampling principle, the new theory shows that it is possible to
reconstruct images or signals of scientific interest accurately and even
exactly from a number of samples which is far smaller than the desired
resolution of the image/signal, e.g., the number of pixels in the image. This
new technique draws from results in several fields of mathematics, including
algebra, optimization, probability theory, and harmonic analysis. We will
discuss some of the key mathematical ideas behind compressive sensing, as well
as its implications to other fields: numerical analysis, information theory,
theoretical computer science, and engineering.


title: A note on the quartic effective action of type IIB superstring

abstract:
  We recast the result of our recent computation of the quartic action of
ten-dimensional IIB supergravity in a manifestly SL(2,R)-covariant form. This
affords us a critical assessment of an earlier conjecture in the literature.


title:
Determination of the fine structure constant with atom interferometry
  and Bloch oscillations

abstract:
  We use Bloch oscillations to transfer coherently many photon momenta to
atoms. Then we can measure accurately the recoil velocity $\hbar k/m$ and
deduce the fine structure constant $\alpha$. The velocity variation due to
Bloch oscillations is measured using atom interferometry. This method yields to
a value of the fine structure constant $\alpha^{-1}= 137.035 999 45 (62)$ with
a relative uncertainty of about $4.5 \times 10^{-9}$.


title:
Creation and manipulation of anyons in a layered superconductor-2DEG
  system

abstract:
  We describe and analyze in detail our recent theoretical proposal for the
realization and manipulation of anyons in a weakly interacting system
consisting of a two-dimensional electron gas in the integer quantum Hall regime
adjacent to a type-II superconducting film with an artificial array of pinning
sites. The anyon is realized in response to a defect in the pinned vortex
lattice and carries a charge \pm e/2 and a statistical angle pi/4. We establish
this result, both analytically and numerically, in three complementary
approaches: (i) a continuum model of two-dimensional electrons in the vortex
lattice of the superconducting film; (ii) a minimal tight-binding lattice model
that captures the essential features of the system; and (iii) an effective
theory of the superconducting vortex lattice superposed on the integer quantum
Hall state. We propose a novel method to measure the fractional charge directly
in a bulk transport experiment and an all-electric setup for an ``anyon
shuttle'' implementing the braiding operations. We briefly discuss conditions
for fabricating the system in the lab and its potential applications in quantum
information processing with non-Abelian anyons.


title: Choosing a penalty for model selection in heteroscedastic regression

abstract:
  We consider the problem of choosing between several models in least-squares
regression with heteroscedastic data. We prove that any penalization procedure
is suboptimal when the penalty is a function of the dimension of the model, at
least for some typical heteroscedastic model selection problems. In particular,
Mallows' Cp is suboptimal in this framework. On the contrary, optimal model
selection is possible with data-driven penalties such as resampling or $V$-fold
penalties. Therefore, it is worth estimating the shape of the penalty from
data, even at the price of a higher computational cost. Simulation experiments
illustrate the existence of a trade-off between statistical accuracy and
computational complexity. As a conclusion, we sketch some rules for choosing a
penalty in least-squares regression, depending on what is known about possible
variations of the noise-level.


title:
Trial wave functions, molecular states, and ro-vibrational spectra in
  the lowest Landau level: A universal description for bosons and fermions

abstract:
  Through the introduction of a class of appropriate translationally invariant
trial wave functions, we show that the strong correlations in the lowest Landau
level (LLL) reflect in finite systems the emergence of intrinsic point-group
symmetries associated with rotations and vibrations of molecules formed through
particle localization. This molecular description is universal, being valid for
both bosons and fermions, for both the yrast and excited states of the LLL
spectra, and for both low and high angular momenta. This physical picture is
fundamentally different from the "quantum-fluid" one associated with
Jastrow-type trial functions.


title:
Algorithm for simulation of quantum many-body dynamics using dynamical
  coarse graining

abstract:
  An algorithm for simulation of quantum many-body dynamics having su(2)
spectrum-generating algebra is developed. The algorithm is based on the idea of
dynamical coarse-graining. The original unitary dynamics of the target
observables, the elements of the spectrum-generating algebra, is simulated by a
surrogate open-system dynamics, which can be interpreted as weak measurement of
the target observables, performed on the evolving system. The open-system state
can be represented by a mixture of pure states, localized in the phase-space.
The localization reduces the scaling of the computational resources with the
Hilbert space dimension n by factor n^{3/2}/ln n compared to conventional
sparse-matrix methods. The guidelines for the choice of parameters for the
simulation are presented and the scaling of the computational resources with
the Hilbert space dimension of the system is estimated. The algorithm is
applied to the simulation of the dynamics of systems of 2*10^4 and 2*10^6 cold
atoms in the double-well trap, described by the two-sites Bose-Hubbard model.


title:
Orientation-reversing involutions of the genus 3 Arnoux-Yoccoz surface
  and related surfaces

abstract:
  We present a new description of the genus 3 Arnoux--Yoccoz translation
surface in terms of its Delaunay polygons and show that, up to affine
equivalence, it belongs to two families of surfaces whose isometry groups
include the dihedral group of the square.


title: Binary Classification Based on Potentials

abstract:
  We introduce a simple and computationally trivial method for binary
classification based on the evaluation of potential functions. We demonstrate
that despite the conceptual and computational simplicity of the method its
performance can match or exceed that of standard Support Vector Machine
methods.


title:
Non-colliding Jacobi processes as limits of Markov chains on
  Gelfand-Tsetlin graph

abstract:
  We introduce a stochastic dynamics related to the measures that arise in
harmonic analysis on the infinite-dimensional unitary group. Our dynamics is
obtained as a limit of a sequence of natural Markov chains on Gelfand-Tsetlin
graph. We compute finite-dimensional distributions of the limit Markov process,
the generator and eigenfunctions of the semigroup related to this process. The
limit process can be identified with Doob h-transform of a family of
independent diffusions. Space-time correlation functions of the limit process
have a determinantal form.


title:
Comparison of Binary Classification Based on Signed Distance Functions
  with Support Vector Machines

abstract:
  We investigate the performance of a simple signed distance function (SDF)
based method by direct comparison with standard SVM packages, as well as
K-nearest neighbor and RBFN methods. We present experimental results comparing
the SDF approach with other classifiers on both synthetic geometric problems
and five benchmark clinical microarray data sets. On both geometric problems
and microarray data sets, the non-optimized SDF based classifiers perform just
as well or slightly better than well-developed, standard SVM methods. These
results demonstrate the potential accuracy of SDF-based methods on some types
of problems.


title: Collapse Barriers and Halo Abundance: Testing the Excursion Set Ansatz

abstract:
  Our heuristic understanding of the abundance of dark matter halos centers
around the concept of a density threshold, or "barrier", for gravitational
collapse. If one adopts the ansatz that regions of the linearly evolved density
field smoothed on mass scale M with an overdensity that exceeds the barrier
will undergo gravitational collapse into halos of mass M, the corresponding
abundance of such halos can be estimated simply as a fraction of the mass
density satisfying the collapse criterion divided by the mass M. The key
ingredient of this ansatz is therefore the functional form of the collapse
barrier as a function of mass M or, equivalently, of the variance sigma^2(M).
Several such barriers based on the spherical, Zel'dovich, and ellipsoidal
collapse models have been extensively discussed. Using large scale cosmological
simulations, we show that the relation between the linear overdensity and the
mass variance for regions that collapse to form halos by the present epoch
resembles expectations from dynamical models of ellipsoidal collapse. However,
we also show that using such a collapse barrier with the excursion set ansatz
predicts a halo mass function inconsistent with that measured directly in
cosmological simulations. This inconsistency demonstrates a failure of the
excursion set ansatz as a physical model for halo collapse. We discuss
implications of our results for understanding the collapse epoch for halos as a
function of mass, and avenues for improving consistency between analytical
models for the collapse epoch and the results of cosmological simulations.


title:
Grid Based Linear Neutrino Perturbations in Cosmological N-body
  Simulations

abstract:
  We present a novel, fast and precise method for including the effect of light
neutrinos in cosmological N-body simulations. The effect of the neutrino
component is included by using the linear theory neutrino perturbations in the
calculation of the gravitational potential in the N-body simulation. By
comparing this new method with the full non-linear evolution first presented in
\cite{Brandbyge1}, where the neutrino component was treated as particles, we
find that the new method calculates the matter power spectrum with an accuracy
better than 1% for \sum m_\nu \lesssim 0.5 eV at z = 0. This error scales
approximately as (\sum m_\nu)^2, making the new linear neutrino method
extremely accurate for a total neutrino mass in the range 0.05 - 0.3 eV. At z =
1 the error is below 0.3% for \sum m_\nu \lesssim 0.5 eV and becomes negligible
at higher redshifts. This new method is computationally much more efficient
than representing the neutrino component by N-body particles.


title: The Discovery Potential of Laser Polarization Experiments

abstract:
  Currently, a number of experiments are searching for vacuum magnetic
birefringence and dichroism, i.e. for dispersive and absorptive features in the
propagation of polarized light along a transverse magnetic field in vacuum. In
this note we calculate the Standard Model contributions to these signatures,
thereby illuminating the discovery potential of such experiments in the search
for new physics. We discuss the three main sources for a Standard Model
contribution to a dichroism signal: photon splitting, neutrino pair production
and production of gravitons.


title: Ultra faint dwarfs: probing early cosmic star formation

abstract:
  We investigate the nature of the newly discovered Ultra Faint dwarf
spheroidal galaxies (UF dSphs) in a general cosmological context simultaneously
accounting for various ``classical`` dSphs and Milky Way properties including
their Metallicity Distribution Function (MDF). To this aim we extend the merger
tree approach previously developed to include the presence of star-forming
minihaloes, and an heuristic prescription for radiative feedback. The model
successfully reproduces both the observed [Fe/H]-Luminosity relation and the
mean MDF of UFs. In this picture UFs are the oldest, most dark matter-dominated
(M/L > 100) dSphs with a total mass M= 10^{7-8}Msun; they are leftovers of
H_2-cooling minihaloes formed at z > 8.5, i.e. before reionization. Their MDF
is broader (because of a more prolonged SF) and shifted towards lower [Fe/H]
(as a result of a lower gas metallicity at the time of formation) than that of
classical dSphs. These systems are very ineffectively star-forming, turning
into stars by z=0 only <3% of the potentially available baryons. We provide a
useful fit for the star formation efficiency of dSphs.


title:
Evolution in the properties of Lyman-alpha emitters from redshifts z ~ 3
  to z ~ 2

abstract:
  Context: Narrow-band surveys for Ly-alpha emitters (LAEs) is a powerful tool
in detecting high, and very high, redshift galaxies. Even though samples are
growing at redshifts z = 3 - 6, the nature of these galaxies is still poorly
known. Aims: To study the properties of z = 2.25 LAEs and compare those with
the properties of z > 3 LAEs. Methods: We present narrow-band imaging made with
the MPG/ESO 2.2m telescope with the WFI detector. We have made a selection for
emission-line objects and find 170 candidate typical LAEs and 17 candidates
which we regard as high UV-transmission LAEs. We have derived the magnitudes of
these objects in 8 bands from u* to Ks, and studied if they have X-ray and/or
radio counterparts. Results: We show that there has been significant evolution
in the properties of LAEs between redshift z ~ 3 and z = 2.25. The spread in
spectral energy distributions (SEDs) at the lower redshift is larger and we
detect a significant AGN contribution in the sample. The distribution of the
equivalent widths is narrower than at z ~ 3, with only a few candidates with
rest-frame equivalent width above the predicted limit of 240 A. The star
formation rates derived from the Ly-alpha emission compared to that derived
from the UV emission are lower by on average a factor of ~ 1.8, indicating a
large absorption of dust. Conclusion: LAEs at redshift z = 2.25 may be more
evolved than LAEs at higher redshift. The red SEDs imply more massive, older
and/or more dusty galaxies at lower redshift than observed at higher redshifts.
The decrease in equivalent widths and star formation rates indicate more
quiescent galaxies, with in general less star formation than in higher redshift
galaxies. At z = 2.25, AGN appear to be more abundant and also to contribute
more to the LAE population. [Abridged]


title:
Three-Dimensional Simulations of Dynamics of Accretion Flows Irradiated
  by a Quasar

abstract:
  We study the axisymmetric and non-axisymmetric, time-dependent hydrodynamics
of gas that is under the influence of the gravity of a super massive black hole
(SMBH) and the radiation force produced by a radiatively efficient flow
accreting onto the SMBH. We have considered two cases: (1) the formation of an
outflow from the accretion of the ambient gas without rotation and (2) that
with weak rotation. The main goals of this study are: (1) to examine if there
is a significant difference between the models with identical initial and
boundary conditions but in different dimensionality (2-D and 3-D), and (2) to
understand the gas dynamics in AGN. Our 3-D simulations of a non-rotating gas
show small yet noticeable non-axisymmetric small-scale features inside the
outflow. The outflow as a whole and the inflow do not seem to suffer from any
large-scale instability. In the rotating case, the non-axisymmetric features
are very prominent, especially in the outflow which consists of many cold dense
clouds entrained in a smoother hot flow. The 3-D outflow is non-axisymmetric
due to the shear and thermal instabilities. In both 2-D and 3-D simulations,
gas rotation increases the outflow thermal energy flux, but reduces the outflow
mass and kinetic energy fluxes. Rotation also leads to time variability and
fragmentation of the outflow in the radial and latitudinal directions. The
collimation of the outflow is reduced in the models with gas rotation. The time
variability in the mass and energy fluxes is reduced in the 3-D case because of
the outflow fragmentation in the azimuthal direction. The virial mass estimated
from the kinematics of the dense cold clouds found in our 3-D simulations of
rotating gas underestimates the actual mass used in the simulations by about 40
%. (Abbreviated)


title:
The halo merger rate in the Millennium Simulation and implications for
  observed galaxy merger fractions

abstract:
  We developed a new method to extract halo merger rates from the Millennium
Simulation. First, by removing superfluous mergers that are artifacts of the
FOF halo finder, we find a lower merger rate compared to previous work. The
reductions are more significant at lower redshifts, lower halo masses, and
minor mergers. Our approach agrees better with predictions from the EPS model.
Second, we find that the FOF halo finder overestimates the halo mass by up to
50% for halos that are about to merge, which leads to an additional ~20%
overestimate of the merger rate. Therefore, we define halo masses by including
only gravitationally bound particles. We provide new best-fitting parameters
for a global formula to account for these improvements. In addition, we extract
the merger rate per progenitor halo, as well as per descendant halo. The former
is the quantity that is related to observed galaxy merger fractions when they
are measured via pair counting. At low mass/redshift the merger rate increases
with mass and redshift. At high mass/redshift (for halos with masses a few
times the "knee" of the mass function) these trends break down, and the merger
rate per progenitor halo decreases with mass and increases only moderately with
redshift. Defining the merger rate per progenitor halo also allows us to
quantify the rate at which halos are being accreted onto larger halos. We
provide an analytic formula to convert given merger rates per descendant halo
into merger rates per progenitor halo. Finally, we perform a comparison between
observed merger fractions and the fraction of halos that have undergone a major
merger during the recent dynamical friction time, and find a fair agreement,
within the large uncertainties of the observations. Our new halo merger trees
are available at http://www.mpe.mpg.de/ir/MillenniumMergerTrees/.


title: Cosmology of F-theory GUTs

abstract:
  In this paper we study the interplay between the recently proposed F-theory
GUTs and cosmology. Despite the fact that the parameter range for F-theory GUT
models is very narrow, we find that F-theory GUTs beautifully satisfy most
cosmological constraints without any further restrictions. The viability of the
scenario hinges on the interplay between various components of the axion
supermultiplet, which in F-theory GUTs is also responsible for breaking
supersymmetry. In these models, the gravitino is the LSP and develops a mass by
eating the axino mode. The radial component of the axion supermultiplet known
as the saxion typically begins to oscillate in the early Universe, eventually
coming to dominate the energy density. Its decay reheats the Universe to a
temperature of ~ 1 GeV, igniting BBN and diluting all thermal relics such as
the gravitino by a factor of ~ 10^(-4) - 10^(-5) such that gravitinos
contribute a sizable component of the dark matter. In certain cases,
non-thermally produced relics such as the axion, or gravitinos generated from
the decay of the saxion can also contribute to the abundance of dark matter.
Remarkably enough, this cosmological scenario turns out to be independent of
the initial reheating temperature of the Universe. This is due to the fact that
the initial oscillation temperature of the saxion coincides with the freeze out
temperature for gravitinos in F-theory GUTs. We also find that saxion dilution
is compatible with generating the desired baryon asymmetry from standard
leptogenesis. Finally, the gravitino mass range in F-theory GUTs is 10-100 MeV,
which interestingly coincides with the window of values required for the decay
of the NLSP to solve the problem of Li(7) over-production.


title: $\hbar$-adic quantum vertex algebras and their modules

abstract:
  This is a paper in a series to study vertex algebra-like structures arising
from various algebras including quantum affine algebras and Yangians. In this
paper, we study notions of $\hbar$-adic nonlocal vertex algebra and
$\hbar$-adic (weak) quantum vertex algebra, slightly generalizing
Etingof-Kazhdan's notion of quantum vertex operator algebra. For any
topologically free $\C[[\h]]$-module $W$, we study $\hbar$-adically compatible
subsets and $\hbar$-adically $\S$-local subsets of $(\End W)[[x,x^{-1}]]$. We
prove that any $\hbar$-adically compatible subset generates an $\hbar$-adic
nonlocal vertex algebra with $W$ as a module and that any $\hbar$-adically
$\S$-local subset generates an $\hbar$-adic weak quantum vertex algebra with
$W$ as a module. A general construction theorem of $\hbar$-adic nonlocal vertex
algebras and $\hbar$-adic quantum vertex algebras is obtained. As an
application we associate the centrally extended double Yangian of $\sl_{2}$ to
$\hbar$-adic quantum vertex algebras.


title:
The Diffuse Supernova Neutrino Background is detectable in
  Super-Kamiokande

abstract:
  The Diffuse Supernova Neutrino Background (DSNB) provides an immediate
opportunity to study the emission of MeV thermal neutrinos from core-collapse
supernovae. The DSNB is a powerful probe of stellar and neutrino physics,
provided that the core-collapse rate is large enough and that its uncertainty
is small enough. To assess the important physics enabled by the DSNB, we start
with the cosmic star formation history of Hopkins & Beacom (2006) and confirm
its normalization and evolution by cross-checks with the supernova rate,
extragalactic background light, and stellar mass density. We find a sufficient
core-collapse rate with small uncertainties that translate into a variation of
+/- 40% in the DSNB event spectrum. Considering thermal neutrino spectra with
effective temperatures between 4-6 MeV, the predicted DSNB is within a factor
4-2 below the upper limit obtained by Super-Kamiokande in 2003. Furthermore,
detection prospects would be dramatically improved with a gadolinium-enhanced
Super-Kamiokande: the backgrounds would be significantly reduced, the fluxes
and uncertainties converge at the lower threshold energy, and the predicted
event rate is 1.2-5.6 events /yr in the energy range 10-26 MeV. These results
demonstrate the imminent detection of the DSNB by Super-Kamiokande and its
exciting prospects for studying stellar and neutrino physics.


title:
Permutation Symmetric Critical Phases in Disordered Non-Abelian Anyonic
  Chains

abstract:
  Topological phases supporting non-abelian anyonic excitations have been
proposed as candidates for topological quantum computation. In this paper, we
study disordered non-abelian anyonic chains based on the quantum groups
$SU(2)_k$, a hierarchy that includes the $\nu=5/2$ FQH state and the proposed
$\nu=12/5$ Fibonacci state, among others. We find that for odd $k$ these
anyonic chains realize infinite randomness critical {\it phases} in the same
universality class as the $S_k$ permutation symmetric multi-critical points of
Damle and Huse (Phys. Rev. Lett. 89, 277203 (2002)). Indeed, we show that the
pertinent subspace of these anyonic chains actually sits inside the ${\mathbb
Z}_k \subset S_k$ symmetric sector of the Damle-Huse model, and this ${\mathbb
Z}_k$ symmetry stabilizes the phase.


title: Operator Algebras with Unique Preduals

abstract:
  We show that every free semigroup algebras has a (strongly) unique Banach
space predual. We also provide a new simpler proof that a weak*-closed unital
operator operator algebra containing a weak* dense subalgebra of compact
operators has a unique Banach space predual.


title:
Evidence for reversible control of magnetization in a ferromagnetic
  material via spin-orbit magnetic field

abstract:
  Conventional computer electronics creates a dichotomy between how information
is processed and how it is stored. Silicon chips process information by
controlling the flow of charge through a network of logic gates. This
information is then stored, most commonly, by encoding it in the orientation of
magnetic domains of a computer hard disk. The key obstacle to a more intimate
integration of magnetic materials into devices and circuit processing
information is a lack of efficient means to control their magnetization. This
is usually achieved with an external magnetic field or by the injection of
spin-polarized currents. The latter can be significantly enhanced in materials
whose ferromagnetic properties are mediated by charge carriers. Among these
materials, conductors lacking spatial inversion symmetry couple charge currents
to spin by intrinsic spin-orbit (SO) interactions, inducing nonequilibrium spin
polarization tunable by local electric fields. Here we show that magnetization
of a ferromagnet can be reversibly manipulated by the SO-induced polarization
of carrier spins generated by unpolarized currents. Specifically, we
demonstrate domain rotation and hysteretic switching of magnetization between
two orthogonal easy axes in a model ferromagnetic semiconductor.


title:
Three-flavour neutrino oscillation update and comments on possible hints
  for a non-zero theta_{13}

abstract:
  We provide a short summary of three-flavour neutrino oscillation parameters
as determined from a global fit to 2008 data, and we comment on possible hints
in favour of a non-zero value of the mixing angle theta_{13} found in
arXiv:0806.2649. We do confirm a hint from solar + KamLAND data at about 1.5
sigma, which can be understood from the recent SNO CC/NC measurment. However,
we show that a claimed hint from atmospheric data is much less robust. It
depends on details of event rate calculations and treatment of theoretical
uncertainties. We could identify two data points showing an 'excess' (at the 1
sigma level) in the SK-I multi-GeV e-like data, which seem to be the origin of
the slight preference for theta_{13} > 0. We point out that once SK-I and SK-II
data are combined this 'excess' disappears, and irrespective of the details of
the analysis, no 'hint' from atmospheric data is obtained for the SK-I and
SK-II combined data set. As a result the global fit of all data leads to a best
fit value of theta_{13} consistent with zero within less than 1 sigma.


title: Power corrections in e+ e- --> pi+ pi-, K+ K- and B --> K pi, pi pi

abstract:
  CLEO-c measurements of the timelike form factors F_pi, F_K at \sqrt{s}=3.671
GeV provide a direct probe of power corrections (PC's) at energies near m_B.
PC's in F_pi, F_K and B \to K pi, pi pi are separated into perturbative and
soft parts. In F_pi, F_K the latter are \ge O(10) larger. A PC fit to the B \to
K pi, pi pi data also yields a \ge O(10) soft-to-perturbative hierarchy for the
QCD penguin PC's. Hence, both can be attributed to dominance of the soft-ovelap
between energetic (approximately) back-to-back collinear partons, and
consistency of the B\to K pi, pi pi fit with the Standard Model appears to be
naturally realized. The CP asymmetries S_{K_s pi^0}, C_{K_s pi^0} are well
determined, providing a clean test for new physics.


title:
New Strong-Field QED Effects at ELI: Nonperturbative Vacuum Pair
  Production

abstract:
  Since the work of Sauter, and Heisenberg, Euler and K\"ockel, it has been
understood that vacuum polarization effects in quantum electrodynamics (QED)
predict remarkable new phenomena such as light-light scattering and pair
production from vacuum. However, these fundamental effects are difficult to
probe experimentally because they are very weak, and they are difficult to
analyze theoretically because they are highly nonlinear and/or nonperturbative.
The Extreme Light Infrastructure (ELI) project offers the possibility of a new
window into this largely unexplored world. I review these ideas, along with
some new results, explaining why quantum field theorists are so interested in
this rapidly developing field of laser science. I concentrate on the
theoretical tools that have been developed to analyze nonperturbative vacuum
pair production.


title: Significant Limb-Brightening in the Inner Parsec of Markarian 501

abstract:
  We present three 43 GHz images and a single 86 GHz image of Markarian 501
from VLBA observations in 2005. The 86 GHz image shows a partially resolved
core with a flux density of about 200 mJy and a size of about 300 Schwarzschild
radii, similar to recent results by Giroletti et al. Extreme limb-brightening
is found in the inner parsec of the jet in the 43 GHz images, providing strong
observational support for a `spine-layer' structure at this distance from the
core. The jet is well resolved transverse to its axis, allowing Gaussian model
components to be fit to each limb of the jet. The spine-layer brightness ratio
and relative sizes, the jet opening angle, and a tentative detection of
superluminal motion in the layer are all discussed.


title: Ground states for three-layer hybrid superconductor

abstract:
  A superconducting hybrid structure composed of three layers is
considerated.The 2D layers interact mutually by higher grade inter-layer
couplings.We determine the possible superconducting modes. Those solutions
enable to discuss the conditions for the onset and enhancement of 3D
superconductivity in such a structure.


title:
On the Geometry of the Second Fundamental Form of Translation Surfaces
  in E3

abstract:
  In this paper we study the second fundamental form of translation surfaces in
E3. We give a non-existence result for polynomial translation surfaces in E3
with vanishing second Gaussian curvature KII. We classify those translation
surfaces for which KII and H are proportional. Finally we obtain that there are
no II-minimal translation surfaces in the Euclidean 3-space.


title: Decays of Charmed Mesons to PV Final States

abstract:
  New data on the decays of the charmed particles $D^0$, $D^+$, and $D_s$ to
$PV$ final states consisting of a light pseudoscalar meson $P$ and a light
vector meson $V$ are analyzed. Following the same methods as in a previous
analysis of $D \to PP$ decays, one can test flavor symmetry, extract key key
amplitudes, and obtain information on relative strong phases. Analyses are
performed for Cabibbo-favored decays and then extended to predict properties of
singly- and doubly-Cabibbo-suppressed processes.


title:
Estimates for the Boltzmann collision operator via radial symmetry and
  Fourier transform

abstract:
  We extend the $L^p$-theory of the Boltzmann collision operator by using
classical techniques based in the Carleman representation and Fourier analysis,
allied to new ideas that exploit the radial symmetry of this operator. We are
then able to greatly simplify existent technical proofs in this theory, extend
the range, and obtain explicit sharp constants in some convolution-like
inequalities for the gain part of the Boltzmann collision operator.


title: The First High-Precision Radial Velocity Search for Extra-Solar Planets

abstract:
  In the late 1970s and early 1980s, the introduction of solid-state,
signal-generating detectors and absorption cells to impose wavelength fiducials
directly on the starlight, the errors in stellar radial velocity (RV)
measurements were reduced to the point where Doppler searches for planets
became feasible. In 1980 we began to use a hydrogen fluoride gas cell with the
CFHT coud\'{e} spectrograph and, for 12 years, monitored RVs of some 29
solar-type stars. Since extra-solar planets were expected to resemble Jupiter
in both mass and orbit, we were awarded only three or four two-night observing
runs each year. In 1988 we highlighted a potential planetary companion to
$\gamma$ Cep (K1 IV), in 1993 one to $\beta$ Gem (K0 III), and another to
$\epsilon$ Eri (K2 V) in 1992. The putative planets all resembled Jovian
systems with periods and masses of 2.5 yr and 1.4 $M_{J}$, 1.6 yr and 2.6
$M_{J}$, and 6.9 yr and 0.9 $M_{J}$, respectively. All three were subsequently
confirmed from more extensive data by the Texas group led by Cochran and Hatzes
who derived the currently accepted orbital elements. None of the systems is
simple and some still question $\epsilon$ Eri b.


title: The pasta phase within density dependent hadronic models

abstract:
  In the present paper we investigate the onset of the pasta phase with
different parametrisations of the density dependent hadronic model and compare
the results with one of the usual parametrisation of the non-linear Walecka
model. The influence of the scalar-isovector virtual delta meson is shown. At
zero temperature two different methods are used, one based on coexistent phases
and the other on the Thomas-Fermi approximation. At finite temperature only the
coexistence phases method is used. npe matter with fixed proton fractions and
in beta-equilibrium are studied. We compare our results with restrictions
imposed on the the values of the density and pressure at the inner edge of the
crust, obtained from observations of the Vela pulsar and recent isospin
diffusion data from heavy-ion reactions, and with predictions from spinodal
calculations.


title:
Fuzzy spaces topology change as a possible solution to the black hole
  information loss paradox

abstract:
  In this paper we argue that modelling the black hole event horizon as a fuzzy
sphere we can get a possible solution to the black hole information loss
paradox.


title:
Graviton and Scalar Two-Point Functions in a CDL Background for General
  Dimensions

abstract:
  We compute the two-point functions of the scalar and graviton in a Coleman-De
Luccia type instanton background in general dimensions. These are analytically
continued to Lorentzian signature. We write the correlator in a form convenient
for examining the "holographic" properties of this background inspired by the
work of Freivogel, Sekino, Susskind and Yeh(FSSY). Based on this, we speculate
on what kind of boundary theory we would have on this background if we assume
that there exists a holographic duality.


title:
Aerodynamic Models For Hurricanes I. Model description and horizontal
  motion of hurricane

abstract:
  Aerodynamic models are developed to describe coherent structures and
transport processes in hurricanes moving over open seas. The models consist of
the lower boundary layer and upper adiabatic layer. Except friction at the
air/sea interface,proposed modeling avoids the common turbulent approximations
while using explicitly or implicitly basic stability constraints. The models
analyze dynamics of upper hurricane adiabatic layer, dynamics and transport
processes in hurricane boundary layer, and genesis and maturing of hurricane.
The proposed modeling provides a rude enough but consistent analytical
description of basic processes in hurricanes. The present paper qualitatively
describes the model of mature hurricane, briefly discusses the basic
thermodynamic relations and aerodynamic equations, and establishes the
principles of horizontal motion for mature hurricane.


title:
Discrimination of two mixed quantum states with maximum confidence and
  minimum probability of inconclusive results

abstract:
  We study an optimized measurement that discriminates two mixed quantum states
with maximum confidence for each conclusive result, thereby keeping the overall
probability of inconclusive results as small as possible. When the rank of the
detection operators associated with the two different conclusive outcomes does
not exceed unity we obtain a general solution. As an application, we consider
the discrimination of two mixed qubit states. Moreover, for the case of
higher-rank detection operators we give a solution for particular states. The
relation of the optimized measurement to other discrimination schemes is also
discussed.


title: An L^1 Ergodic Theorem for Sparse Random Subsequences

abstract:
  We prove an L^1 subsequence ergodic theorem for sequences chosen by
independent random selector variables, thereby showing the existence of
universally L^1-good sequences nearly as sparse as the set of squares. In the
process, we prove that a certain deterministic condition implies a weak maximal
inequality for a sequence of \ell^1 convolution operators.


title: Aerodynamic Models for Hurricanes II. Model of the upper hurricane layer

abstract:
  This second paper of the series (see the first one in [1]) models the
dynamics and structure of upper hurricane layer in adiabatic approximation.
Formulation of simplified aerodynamic model allows analytically express the
radial istributions of pressure and wind speed components. The vertical
evolution of these distributions and hurricane structure in the layer are
described by a coupled set of equations for the vertical mass flux and vertical
momentum balance, averaged over the eye wall cross section. Several realistic
predictions of the model are demonstrated, including the change of directions
for the component of radial wind speed and angular velocity of hurricane with
altitude.


title: Gate Coupling to Nanoscale Electronics

abstract:
  The realization of single-molecule electronic devices, in which a
nanometer-scale molecule is connected to macroscopic leads, requires the
reproducible production of highly ordered nanoscale gaps in which a molecule of
interest is electrostatically coupled to nearby gate electrodes. Understanding
how the molecule-gate coupling depends on key parameters is crucial for the
development of high-performance devices. Here we directly address this,
presenting two- and three-dimensional finite-element electrostatic simulations
of the electrode geometries formed using emerging fabrication techniques. We
quantify the gate coupling intrinsic to these devices, exploring the roles of
parameters believed to be relevant to such devices. These include the thickness
and nature of the dielectric used, and the gate screening due to different
device geometries. On the single-molecule (~1nm) scale, we find that device
geometry plays a greater role in the gate coupling than the dielectric constant
or the thickness of the insulator. Compared to the typical uniform nanogap
electrode geometry envisioned, we find that non-uniform tapered electrodes
yield a significant three orders of magnitude improvement in gate coupling. We
also find that in the tapered geometry the polarizability of a molecular
channel works to enhance the gate coupling.


title: Aerodynamic Models for Hurricanes III. Modeling hurricane boundary layer

abstract:
  The third paper of the series (see previous ones in Refs.[1-2]) discusses
basic physicalprocesses in the (quasi-) steady hurricane boundary layer (HBL),
develops an approximate airflow model, establishes the HBL structure, and
presents integral balance relations for dynamic and thermodynamic variables in
HBL. Models of evaporation and condensation are developed, where the
condensation is treated similarly to the slow combustion theory. A turbulent
approximation for the lower sub-layer of HBL is applied to the sea-air
interaction to establish the observed increase in angular momentum in the outer
region of HBL.A closed set of balance relations has been obtained. Simple
analytical solution of the set yields expressions for the basic dynamic
variables - maximal tangential and radial velocities in hurricane, maximal
vertical speed in eye wall, the affinity speed of hurricane travel, and the
maximal temperature increase after condensation. Estimated values of the
variables seem to be realistic. An attempt is also made to describe the radial
distributions of wind velocity and surface pressure observed in the hurricane
Frederic (1979).


title: Donkin-Koppinen filtration for general linear supergroup

abstract:
  We consider a generalization of Donkin-Koppinen filtrations for coordinate
superalgebras of general linear supergroups. More precisely, if $G=GL(m|n)$ is
a general linear supergroup of (super)degree $(m|n)$, then its coordinate
superalgebra $K[G]$ is a natural $G\times G$-supermodule. For every finitely
generated ideal $\Gamma\subseteq \Lambda\times\Lambda$, the largest
subsupermodule $O_{\Gamma}(K[G])$ of $K[G]$, which has all composition factors
of the form $L(\lambda)\otimes L(\mu)$ where $(\lambda, \mu)\in\Gamma$, has a
decreasing filtration $O_{\Gamma}(K[G])=V_0\supseteq V_1\supseteq...$ such that
$\bigcap_{t\geq 0}V_t=0$ and $V_t/V_{t+1}\simeq V_-(\lambda_t)^*\otimes
H_-^0(\lambda_t)$ for each $t\geq 0$. Here $H_-^0(\lambda)$ is a costandard
$G$-supermodule, and $V_-(\lambda)$ is a standard $G$-supermodule, both of
highest weight $\lambda\in\Lambda$ (see \cite{z}). We deduce the existence of
such a filtration from more general facts about standard and costandard
filtrations in certain highest weight categories which will be proved in
Section 4. Until now, analogous results were known only for highest weight
categories with finite sets of weights. We believe that the reader will find
the results of Section 4 interesting on its own. Finally, we apply our main
result to describe invariants of (co)adjoint action of $G$.


title:
Aerodynamic Models for Hurricanes IV. On the hurricane genesis and
  maturing

abstract:
  This, fourth paper of the series (see previous papers in Refs.[1-3]) derives
approximate equations for future numerical studies of initial evolution of
hurricanes, develops new analytical models of hurricane genesis and maturing,
and presents simple results, which seems to be in accord with observations.
Several remarks on tornados are also made at the end of the paper.


title: Microlocal analysis and evolution equations

abstract:
  Lecture notes from 2008 CMI/ETH Summer School on Evolution Equations. These
notes are an informal introduction to the applications of microlocal methods in
the study of linear evolution equations and spectral theory. Calculi of
pseudodifferential operators and Fourier integral operators are discussed and
axiomatized, but not constructed: the focus is on how to apply these tools.


title: Cyclic Inflation

abstract:
  We present an inflationary model that is geodesically complete and does not
suffer from the transplanckian problem. In most inflationary models, massless
(conformal) scalar field fluctuations in a deSitter background gives rise to a
scale-invariant spectrum. In this work, we realize scale invariant
perturbations from thermal fluctuations in (conformal) radiation during a
radiation dominated contraction era prior to inflation. As the modes exit the
Hubble radius during the contraction phase, scale invariant fluctuations are
indeed generated. After many cycles, we enter into a power-law inflationary
phase, that stretches the modes produced in the previous contraction phase to
scales that we observe today.


title: Meson and nucleon properties from Dyson-Schwinger QCD

abstract:
  We present selected results from a calculation of meson and nucleon
observables in a Green-function approach. A rainbow-ladder truncation of QCD's
Dyson-Schwinger equations is used to solve the respective meson, diquark and
quark-diquark Bethe-Salpeter equations. It allows for a simultaneous
description of meson and nucleon masses and electromagnetic properties from an
effective quark-gluon interaction. The results describe a hadronic quark core
which agrees with lattice data for heavy quarks whereas pion-cloud effects are
missing towards the chiral limit. The neutron's Dirac form factor is negative
due to the presence of axial-vector diquark correlations.


title: Origin of intrinsic Gilbert damping

abstract:
  The damping of magnetization, represented by the rate at which it relaxes to
equilibrium, is successfully modeled as a phenomenological extension in the
Landau-Lifschitz-Gilbert equation. This is the damping torque term known as
Gilbert damping and its direction is given by the vector product of the
magnetization and its time derivative. Here we derive the Gilbert term from
first principles by a non-relativistic expansion of the Dirac equation. We find
that the Gilbert term arises when one calculates the time evolution of the spin
observable in the presence of the full spin-orbital coupling terms, while
recognizing the relationship between the curl of the electric field and the
time varying magnetic induction.


title:
Note on: "Inevitability of Plate Tectonics on Super-Earths" by Valencia,
  O Connell and Sasselov, arXiv preprint 0710.0699

abstract:
  Valencia et al. recently claimed that the mass of a Super-Earth (SE) is a
sole factor in determining whether a SE is tectonically active or not. However,
mass resolving astrometry is unable to discern between a SE and its moons if
any. The fact that no exomoons have been discovered yet is rather a matter of
instrumentation imperfection at the present, not of physical absence of
exomoons. This, with recently discovered relationships between geometric and
physical properties in astronomical bodies (Transiting planets; the Earth)
makes it impossible to know yet if the Wageners (here constraining) supposition
on somehow-tidally caused tectonics holds universally or not also.


title:
Bounds for the discrete correlation of infinite sequences on k symbols
  and generalized Rudin-Shapiro sequences

abstract:
  Motivated by the known autocorrelation properties of the Rudin-Shapiro
sequence, we study the discrete correlation among infinite sequences over a
finite alphabet, where we just take into account whether two symbols are
identical. We show by combinatorial means that sequences cannot be "too"
different, and by an explicit construction generalizing the Rudin-Shapiro
sequence, we show that we can achieve the maximum possible difference.


title: Light element abundances in carbon-enhanced metal-poor stars

abstract:
  We model the evolution of the abundances of light elements in carbon-enhanced
metal-poor (CEMP) stars, under the assumption that such stars are formed by
mass transfer in a binary system. We have modelled the accretion of material
ejected by an asymptotic giant branch star on to the surface of a companion
star. We then examine three different scenarios: one in which the material is
mixed only by convective processes, one in which thermohaline mixing is present
and a third in which both thermohaline mixing and gravitational settling are
taken in to account. The results of these runs are compared to light element
abundance measurements in CEMP stars (primarily CEMP-s stars, which are rich in
$s$-processes elements and likely to have formed by mass transfer from an AGB
star), focusing on the elements Li, F, Na and Mg. None of the elements is able
to provide a conclusive picture of the extent of mixing of accreted material.
We confirm that lithium can only be preserved if little mixing takes place. The
bulk of the sodium observations suggest that accreted material is effectively
mixed but there are also several highly Na and Mg-rich objects that can only be
explained if the accreted material is unmixed. We suggest that the available
sodium data may hint that extra mixing is taking place on the giant branch,
though we caution that the data is sparse.


title: Estimating a monotone trend

abstract:
  Motivated by global warming issues, we consider a time se- ries that consists
of a nondecreasing trend observed with station- ary fluctuations, nonparametric
estimation of the trend under monotonicity assumption is considered. The
rescaled isotonic es- timators at an interior point are shown to converge to
Chernoff's distribution under minimal conditions on the stationary errors.
Since the isotonic estimators suffer from the spiking problem at the end point,
two modifications are proposed. The estima- tion errors for both estimators of
the boundary point are shown to have interesting limiting distributions.
Approximation accu- racies are assessed through simulations. One highlight of
our treatment is the proof of the weak convergence results which involve
several recent techniques developed in the study of con- ditional central limit
questions. These weak convergences can be shown to hold conditionally given the
starting values.


title:
Exact 1-D Model for Coherent Synchrotron Radiation with Shielding and
  Bunch Compression

abstract:
  Coherent Synchrotron Radiation has been studied effectively using a
1-dimensional model for the charge distribution in the realm of small angle
approximations and high energies. Here we use Jefimenko's form of Maxwell's
equations, without such approximations, to calculate the exact wake-fields due
to this effect in multiple bends and drifts. It has been shown before that the
influence of a drift can propagate well into a subsequent bend. We show, for
reasonable parameters, that the influence of a previous bend can also propagate
well into a subsequent bend, and that this is especially important at the
beginning of a bend. Shielding by conducting parallel plates is simulated using
the image charge method. We extend the formalism to situations with compressing
and decompressing distributions, and conclude that simpler approximations to
bunch compression usually overestimates the effect. Additionally, an exact
formula for the coherent power radiated by a Gaussian bunch is derived by
considering the coherent synchrotron radiation spectrum, and is used to check
the accuracy of wake-field calculations.


title: Effects of Line-tying on Resistive Tearing Instability in Slab Geometry

abstract:
  The effects of line-tying on resistive tearing instability in slab geometry
is studied within the framework of reduced magnetohydrodynamics
(RMHD).\citep{KadomtsevP1974,Strauss1976} It is found that line-tying has a
stabilizing effect. The tearing mode is stabilized when the system length $L$
is shorter than a critical length $L_{c}$, which is independent of the
resistivity $\eta$. When $L$ is not too much longer than $L_{c}$, the
growthrate $\gamma$ is proportional to $\eta$ . When $L$ is sufficiently long,
the tearing mode scaling $\gamma\sim\eta^{3/5}$ is recovered. The transition
from $\gamma\sim\eta$ to $\gamma\sim\eta^{3/5}$ occurs at a transition length
$L_{t}\sim\eta^{-2/5}$.


title:
Long-Range Magnetic Interactions Induced by the Lattice Distortions and
  the Origin of the E-type Antiferromagnetic Phase in the Undoped Orthorhombic
  Manganites

abstract:
  With the increase of the lattice distortion, the orthorhombic manganites
$R$MnO$_3$ ($R$$=$ La, Pr, Nd, Tb, and Ho) are known to undergo the phase
transition from the layered A-type antiferromagnetic (AFM) state to the zigzag
E-type AFM state. We consider the microscopic origin of this transition. Our
approach consists of the two parts. First, we construct an effective lattice
fermion model for the manganese 3d-bands and derive parameters of this model
from the first-principles electronic structure calculations. Then, we solve
this model in the Hartree-Fock approximation (HFA) and analyze the behavior of
interatomic magnetic interactions. We argue that the nearest-neighbor
interactions decrease with the distortion and at certain stage start to compete
with the longer range (particularly, second- and third-neighbor) AFM
interactions in the orthorhombic ab-plane, which lead to the formation of the
E-phase. The origin of these interactions is closely related to the orbital
ordering, which takes place in the distorted orthorhombic structure. The model
is able to capture the experimental trend and explain why LaMnO$_3$ develops
the A-type AFM order and why it tends to transform to the E-type AFM order in
the more distorted compounds. Nevertheless, the quantitative agreement with the
experimental data crucially depends on other factors, such as the magnetic
polarization of the oxygen sites and the correlation interactions beyond HFA.


title: Light-Front Holography and Novel Effects in QCD

abstract:
  The correspondence between theories in anti-de Sitter space and conformal
field theories in physical space-time leads to an analytic, semiclassical model
for strongly-coupled QCD. Light-front holography allows hadronic amplitudes in
the AdS fifth dimension to be mapped to frame-independent light-front
wavefunctions of hadrons in physical space-time, thus providing a relativistic
description of hadrons at the amplitude level. We identify the AdS coordinate
$z$ with an invariant light-front coordinate $\zeta$ which separates the
dynamics of quark and gluon binding from the kinematics of constituent spin and
internal orbital angular momentum. The result is a single-variable light-front
Schr\"odinger equation for QCD which determines the eigenspectrum and the
light-front wavefunctions of hadrons for general spin and orbital angular
momentum. The mapping of electromagnetic and gravitational form factors in AdS
space to their corresponding expressions in light-front theory confirms this
correspondence. Some novel features of QCD are discussed, including the
consequences of confinement for quark and gluon condensates and the behavior of
the QCD coupling in the infrared. The distinction between static structure
functions such as the probability distributions computed from the square of the
light-front wavefunctions versus dynamical structure functions which include
the effects of rescattering is emphasized. A new method for computing the
hadronization of quark and gluon jets at the amplitude level, an event
amplitude generator, is outlined.


title:
Symmetry Breaking and Self-trapping of a Dipolar Bose-Einstein
  Condensate in a Double-well Potential

abstract:
  The quantum self-trapping phenomenon of a Bose-Einstein condensate (BEC)
represents a remarkable nonlinear effect of wide interest. By considering a
purely dipolar BEC in a double-well potential, we study how the dipole
orientation affects the ground state structure and the transition between
self-trapping and Josephson oscillation in dynamics. Three-dimensional
numerical results and an effective two-mode model demonstrate that the onset of
self-trapping of a dipolar BEC can be radically modified by the dipole
orientation. We also analyze the failure of the two-mode model in predicting
the rate of Josephson oscillations. We hope that our results can motivate
experimental work as well as future studies of self-trapping of ultracold
dipolar gases in optical lattices.


title:
Kerr-Schild ansatz in Einstein-Gauss-Bonnet gravity: An exact vacuum
  solution in five dimensions

abstract:
  As is well-known, Kerr-Schild metrics linearize the Einstein tensor. We shall
see here that they also simplify the Gauss-Bonnet tensor, which turns out to be
only quadratic in the arbitrary Kerr-Schild function f when the seed metric is
maximally symmetric. This property allows us to give a simple analytical
expression for its trace, when the seed metric is a five dimensional maximally
symmetric spacetime in spheroidal coordinates with arbitrary parameters a and
b. We also write in a (fairly) simple form the full Einstein-Gauss-Bonnet
tensor (with a cosmological term) when the seed metric is flat and the
oblateness parameters are equal, a=b. Armed with these results we give in a
compact form the solution of the trace of the Einstein-Gauss-Bonnet field
equations with a cosmological term and a different than b. We then examine
whether this solution for the trace does solve the remaining field equations.
We find that it does not in general, unless the Gauss-Bonnet coupling is such
that the field equations have a unique maximally symmetric solution.


title:
Eccentricity modulation of a close-in planet by a companion -
  application to GJ 436 system

abstract:
  GJ 436b is a Neptune-size planet with 23.2 Earth masses in an elliptical
orbit of period 2.64 days and eccentricity 0.16. With a typical tidal
dissipation factor (Q' ~ 10^6) as that of a giant planet with convective
envelope, its orbital circularization timescale under internal tidal
dissipation is around 1 Gyr, at least two times less than the stellar age (>3
Gyr). A plausible mechanism is that the eccentricity of GJ 436b is modulated by
a planetary companion due to their mutual perturbation. Here we investigate
this possibility from the dynamical viewpoint. A general method is given to
predict the possible locations of the dynamically coupled companions, including
in nearby/distance non-resonant or mean motion resonance orbits with the first
planet. Applying the method to GJ 436 system, we find it is very unlikely that
the eccentricity of GJ 436b is maintained at the present location by a
nearby/distance companion through secular perturbation or mean motion
resonance. In fact, in all these simulated cases, GJ 436b will undergo
eccentricity damp and orbital decay, leaving the present location within the
stellar age. However, these results do not rule out the possible existence of
planet companions in nearby/distance orbits, although they are not able to
maintain the eccentricity of GJ 436b.


title:
Layer-by-layer growth and growth-mode transition of SrRuO3 thin films on
  atomically flat single-terminated SrTiO3 (111) surfaces

abstract:
  We report on growth-mode transitions in the growth of SrRuO3 thin films on
atomically flat Ti4+ single-terminated SrTiO3 (111) substrates, investigated by
reflection high-energy electron diffraction and atomic force microscopy. Over
the first ~9 unit cells, the dominant growth mode changes from island to
layer-by-layer for the growth rate of 0.074 unit cells/sec and the growth
temperature of 700 C. Moreover, in the course of growing SrRuO3 films, the
governing growth mode of interest can be manipulated by changing the growth
temperature and the growth rate, which change allows for the selection of the
desired layer-by-layer mode. The present study thus paves the way for
integrations of SrRuO3 thin layers into (111)-orientated oxide
heterostructures, and hence multi-functional devices, requiring control of the
sharp atomic-level interfaces and the layer-by-layer growth mode.


title:
Optimal pair density functional for description of nuclei with large
  neutron excess

abstract:
  Toward a universal description of pairing properties in nuclei far from
stability, we extend the energy density functional by enriching the isovector
density dependence in the particle-particle channel (pair density functional,
pair-DF). We emphasize the necessity of both the linear and quadratic isovector
density terms. The parameters are optimized by the Hartree-Fock-Bogoliubov
calculation for 156 nuclei of the mass number A=118-196 and the asymmetry
parameter (N-Z)/A<0.25. We clarify that the pair-DF should include the
isovector density dependence in order to take into account the effect of the
isoscalar and isovector effective masses in the particle-hole channel
consistently. The different Skyrme forces can give the small difference in the
pairing gaps toward the neutron drip line, if the optimal pair-DF consistent
with the particle-hole channel is employed.


title:
Conventional $s$-Wave Superconductivity in Noncentrosymmetric
  Ir$_2$Ga$_9$: $^{71}$Ga-NQR Evidence

abstract:
  We report a $^{71}$Ga nuclear-quadrupole-resonance (NQR) study on the
characteristics of superconductivity in noncentrosymmetric Ir$_2$Ga$_9$ at zero
field (H=0). The $^{71}$Ga-NQR measurements have revealed that $1/T_1$ has the
clear coherence peak just below $T_{\rm c}$, and decreases exponentially upon
further cooling in Ir$_2$Ga$_9$. From these results, Ir$_2$Ga$_9$ is concluded
to be the conventional s-wave superconductor. Despite the lack of spatial
centrosymmetry, there are no evidence for unconventional superconducting state
ascribed to ASOC in Ir$_2$Ga$_9$.


title:
Reconnectionless CME eruption: putting the Aly-Sturrock conjecture to
  rest

abstract:
  We demonstrate that magnetic reconnection is not necessary to initiate fast
CMEs. The Aly-Sturrock conjecture states that the magnetic energy of a given
force free boundary field is maximized when the field is open. This is
problematic for CME initiation because it leaves little or no magnetic energy
to drive the eruption, unless reconnection is present to allow some of the
field to escape without opening. Thus, it has been thought that reconnection
must be present to initiate CMEs. This theory has not been subject to rigorous
numerical testing because conventional MHD numerical models contain numerical
diffusion, which introduces uncontrolled numerical reconnection. We use a
quasi-Lagrangian simulation technique to run the first controlled experiments
of CME initiation in the complete lack of reconnection. We find that a flux
rope confined by an arcade, when twisted beyond a critical amount, can escape
to an open state, allowing some of the surrounding arcade to shrink and
releasing magnetic energy from the global field. This mechanism includes a true
ideal MHD instability. We conclude that reconnection is not a necessary trigger
for fast CME eruptions.


title: Modified gravity without new degrees of freedom

abstract:
  We show that the new type of "non-metric" gravity theories introduced
independently by Bengtsson and Krasnov can in fact be reexpressed explicitely
as a metrical theory coupled to an auxiliary field. We unravel why such
theories possess only one propagating graviton by looking at the quadratic
perturbation around a fixed solution. And we give a general construction
principle with a new class of example of such modified gravity theories still
possessing only two propagating degrees of freedom.


title: Ultrahigh dimensional variable selection: beyond the linear model

abstract:
  Variable selection in high-dimensional space characterizes many contemporary
problems in scientific discovery and decision making. Many frequently-used
techniques are based on independence screening; examples include correlation
ranking (Fan and Lv, 2008) or feature selection using a two-sample t-test in
high-dimensional classification (Tibshirani et al., 2003). Within the context
of the linear model, Fan and Lv (2008)showed that this simple correlation
ranking possesses a sure independence screening property under certain
conditions and that its revision, called iteratively sure independent screening
(ISIS), is needed when the features are marginally unrelated but jointly
related to the response variable. In this paper, we extend ISIS, without
explicit definition of residuals, to a general pseudo-likelihood framework,
which includes generalized linear models as a special case. Even in the
least-squares setting, the new method improves ISIS by allowing variable
deletion in the iterative process. Our technique allows us to select important
features in high-dimensional classification where the popularly used two-sample
t-method fails. A new technique is introduced to reduce the false discovery
rate in the feature screening stage. Several simulated and two real data
examples are presented to illustrate the methodology.


title:
The PAMELA and ATIC Excesses From a Nearby Clump of Neutralino Dark
  Matter

abstract:
  In this letter, we suggest that a nearby clump of 600-1000 GeV neutralinos
may be responsible for the excesses recently observed in the cosmic ray
positron and electron spectra by the PAMELA and ATIC experiments. Although
neutralino dark matter annihilating throughout the halo of the Milky Way is
predicted to produce a softer spectrum than is observed, and violate
constraints from cosmic ray antiproton measurements, a large nearby (within 1-2
kiloparsecs of the Solar System) clump of annihilating neutralinos can lead to
a spectrum which is consistent with PAMELA and ATIC, while also producing an
acceptable antiproton flux. Furthermore, the presence of a large dark matter
clump can potentially accommodate the very large annihilation rate required to
produce the PAMELA and ATIC signals.


title:
Neutrino Mass Matrix Related to Up-Quark Masses and Nearly Tribimaximal
  Mixing -- Based on a Yukawaon model --

abstract:
  Based on a new approach (the so-called Yukawaon model) to the mass spectra
and mixings, a neutrino mass matrix which is described in terms of the up-quark
masses and CKM matrix parameters is proposed. The mass matrix successfully
leads to a nearly tribimaximal mixing without assuming any discrete symmetry.


title: On the intersections of solvable Hall subgroups in finite groups

abstract:
  In the paper we consider the following conjecture: if a finite group $G$
possesses a solvable $\pi$-Hall subgroup $H$, then there exist elements
$x,y,z,t\in G$ such that the identity $H\cap H^x\cap H^y\cap H^z\cap
H^t=O_\pi(G)$ holds. The minimal counter example is shown to be an almost
simple group of Lie type.