title:
A low-redshift galaxy cluster X-ray Temperature Function incorporating
  Suzaku data

abstract:
  We present the first results of a survey of 14 low redshift galaxy clusters
using Suzaku. Although luminous (L_x> 1\times 10^{43} erg s^{-1} (0.1-2.4
keV)), these clusters have no prior pointed X-ray data. Together with 47 other
systems they form a flux limited sample (f_x >1.0 \times 10^{-11} erg
s^{-1}cm^{-2} (0.1-2.4 keV)) with z<0.1 in the northern celestial hemisphere.
Using this total sample we evaluate the local $L-T$ relationship and the local
cluster temperature function. Suzaku temperature measurements appear to be in
accord with those of other missions. General agreement is found with other
published estimates of the low redshift cluster temperature function, however
the sample used here exhibits slightly lower space densities at gas
temperatures below 4-5 keV. We find a corresponding deficit in the number of
clusters with temperatures between approximately 4.5 and 5.5 keV. Although at
low significance, a similar feature exists in previous low redshift cluster
datasets. We suggest that low-redshift cluster samples, while crucial for
calibrating precision cosmology measurements, must be used with caution due to
their limited size and susceptibility to the effects of cosmic variance.


title:
Dynamical Constraints on The Masses of the Nuclear Star Cluster and
  Black Hole in the Late-Type Spiral Galaxy NGC 3621

abstract:
  NGC 3621 is a late-type (Sd) spiral galaxy with an active nucleus, previously
detected through mid-infrared [Ne V] line emission. Archival Hubble Space
Telescope (HST) images reveal that the galaxy contains a bright and compact
nuclear star cluster. We present a new high-resolution optical spectrum of this
nuclear cluster, obtained with the ESI Spectrograph at the Keck Observatory.
The nucleus has a Seyfert 2 emission-line spectrum at optical wavelengths,
supporting the hypothesis that a black hole is present. The line-of-sight
stellar velocity dispersion of the cluster is sigma=43+/-3 km/s, one of the
largest dispersions measured for any nuclear cluster in a late-type spiral
galaxy. Combining this measurement with structural parameters measured from
archival HST images, we carry out dynamical modeling based on the Jeans
equation for a spherical star cluster containing a central point mass. The
maximum black hole mass consistent with the measured stellar velocity
dispersion is 3*10^6 solar masses. If the black hole mass is small compared
with the cluster's stellar mass, then the dynamical models imply a total
stellar mass of ~1*10^7 solar masses, which is consistent with rough estimates
of the stellar mass based on photometric measurements from HST images. From
structural decomposition of 2MASS images, we find no clear evidence for a bulge
in NGC 3621; the galaxy contains at most a very faint and inconspicuous
pseudobulge component (M_K>-17.6 mag). NGC 3621 provides one of the best
demonstrations that very late-type spirals can host both active nuclei and
nuclear star clusters, and that low-mass black holes can occur in disk galaxies
even in the absence of a substantial bulge.


title:
Tightening the knot in phytochrome by single molecule atomic force
  microscopy

abstract:
  A growing number of proteins have been shown to adopt knotted folds. Yet the
biological roles and biophysical properties of these knots remain poorly
understood. We have used protein engineering and atomic force microscopy to
explore single-molecule mechanics of the figure-of-eight knot in the
chromophore-binding domain of the red/far red photoreceptor, phytochrome. Under
load, apo phytochrome unfolds at forces of ~47 pN, while phytochrome carrying
its covalently bound tetrapyrrole chromophore unfolds at ~73 pN. These forces
are among the lowest measured in mechanical protein unfolding, hence the
presence of the knot does not automatically indicate a super-stable protein.
Our experiments reveal a stable intermediate along the mechanical unfolding
pathway, reflecting sequential unfolding of two distinct subdomains in
phytochrome, potentially the GAF and PAS domains. For the first time, our
experiments allow direct determination of knot size under load. In the unfolded
chain, the tightened knot is reduced to 17 amino acids, resulting in apparent
shortening of the polypeptide chain by 6.2 nm. Steered molecular dynamics
simulations corroborate this number. Finally, we found that covalent
phytochrome dimers created for these experiments retain characteristic
photoreversibility, unexpectedly arguing against dramatic rearrangement of the
native GAF dimer interface upon photoconversion.


title: Structure-Property Relation of SrTiO3-LaAlO3 Interfaces

abstract:
  A large variety of transport properties have been observed at the interface
between the insulating oxides SrTiO3 and LaAlO3 such as insulation, 2D
interface metallicity, 3D bulk metallicity, Kondo scattering, magnetism and
superconductivity. The relation between the structure and the properties of the
SrTiO3-LaAlO3 interface can be explained in a meaningful way by taking into
account the relative contribution of three structural aspects: oxygen
vacancies, structural deformations (including cation disorder) and electronic
interface reconstruction. The emerging phase diagram is much richer than for
related bulk oxides due to the occurrence of interface electronic
reconstruction. The observation of this interface phenomenon is a display of
recent advances in thin film deposition and characterization techniques, and
provides an extension to the range of exceptional electronic properties of
complex oxides.


title: Minimal SO(10) splits supersymmetry

abstract:
  A good fit of the fermion masses and mixings has been found in the minimal
renormalizable supersymmetric SO(10). This solution needs a strongly split
supersymmetry breaking scenario with gauginos and higgsinos around 100 TeV,
sfermions close to 10^14 GeV and a low GUT scale of around 6 10^15 GeV. We
predict fast proton decays through SO(10) type of d=6 operators and the
leptonic mixing angle theta_13 approximately 0.1.


title: Interacting Dipoles in Type-I Clathrates: Why Glass-like though Crystal?

abstract:
  Almost identical thermal properties of type-I clathrate compounds to those of
glasses follow naturally from the consideration that off-centered guest ions
possess electric dipole moments. Local fields from neighbor dipoles create many
potential minima in the configuration space. A theoretical analysis based on
two-level tunneling states demonstrates that interacting dipoles are a key to
quantitatively explain the glass-like behaviors of low-temperature thermal
properties of type-I clathrate compounds with off-centered guest ions.From this
analysis, we predict the existence of a glass transition.


title: The Julia sets of basic uniCremer polynomials of arbitrary degree

abstract:
  Let $P$ be a polynomial of degree $d$ with a Cremer point $p$ and no
repelling or parabolic periodic bi-accessible points. We show that there are
two types of such Julia sets $J_P$. The \emph{red dwarf} $J_P$ are nowhere
connected im kleinen and such that the intersection of all impressions of
external angles is a continuum containing $p$ and the orbits of all critical
images. The \emph{solar} $J_P$ are such that every angle with dense orbit has a
degenerate impression disjoint from other impressions and $J_P$ is connected im
kleinen at its landing point. We study bi-accessible points and locally
connected models of $J_P$ and show that such sets $J_P$ appear through
polynomial-like maps for generic polynomials with Cremer points.


title: Localized factorizations of integers

abstract:
  We determine the order of magnitude of H^{(k+1)}(x,\vec{y},2\vec{y}), the
number of integers up to x that are divisible by a product d_1...d_k with
y_i<d_i\le 2y_i, when the numbers \log y_1,...,\log y_k have the same order of
magnitude and k\ge 2. This generalizes a result by K. Ford when k=1. As a
corollary of these bounds, we determine the number of elements up to
multiplicative constants that appear in a (k+1)-dimensional multiplication
table as well as how many distinct sums of k+1 Farey fractions there are modulo
1.


title:
Delta F=2 Observables and Fine-Tuning in a Warped Extra Dimension with
  Custodial Protection

abstract:
  We present a complete study of Delta S = 2 and Delta B = 2 processes in a
warped extra dimensional model with a custodial protection of Z b_L bar b_L,
including epsilon_K, Delta M_K, Delta M_s, Delta M_d, A^q_SL, Delta Gamma_q,
A_CP(B_d -> psi K_S) and A_CP(B_s -> psi phi). These processes are affected by
tree level contributions from Kaluza-Klein gluons, the heavy KK photon, new
heavy electroweak gauge bosons Z_H and Z', and in principle by tree level Z
contributions. We confirm recent findings that the fully anarchic approach
where all the hierarchies in quark masses and weak mixing angles are
geometrically explained seems implausible and we confirm that the KK mass scale
M_KK generically has to be at least ~20TeV to satisfy the epsilon_K constraint.
We point out, however, that there exist regions in parameter space with only
modest fine-tuning in the 5D Yukawa couplings which satisfy all existing Delta
F = 2 and electroweak precision constraints for scales M_KK ~3TeV in reach of
the LHC. Simultaneously we find that A_CP(B_s -> psi phi) and A^s_SL can be
much larger than in the SM as indicated by recent results from CDF and D0 data.
We point out that for B_{d,s} physics Delta F = 2 observables the complex
(Z_H,Z') can compete with KK gluons, while the tree level Z and KK photon
contributions are very small. In particular we point out that the Z d^i_L bar
d^j_L couplings are protected by the custodial symmetry. As a by-product we
show the relation of the RS flavour model to the Froggatt-Nielsen mechanism and
we provide analytic formulae for the effective flavour mixing matrices in terms
of the fundamental 5D parameters.


title: Multifractal analysis for multimodal maps

abstract:
  Given a multimodal interval map $f:I \to I$ and a H\"older potential $\phi:I
\to \mathbb{R}$, we study the dimension spectrum for equilibrium states of
$\phi$. The main tool here is inducing schemes, used to overcome the presence
of critical points. The key issue is to show that enough points are `seen' by a
class of inducing schemes. We also compute the Lyapunov spectrum. We obtain the
strongest results when $f$ is a Collet-Eckmann map, but our analysis also holds
for maps satisfying much weaker growth conditions.


title: Lifting of Characters for Nonlinear Simply Laced Groups

abstract:
  One aspect of the Langlands program for linear groups is lifting of
characters, which relates virtual representations on a group $G$ with those on
an endoscopic group for $G$. The goal of this paper is to extend this theory to
nonlinear two-fold covers of real groups in the simply laced case. Suppose
$\tG$ is a two-fold cover of a real reductive group $G$. The main result is
that there is an operation, denoted $\Lift_G^{\tG}$, taking a stable virtual
character of $G$ to 0 or a virtual genuine character of $\tG$, and
$\Lift_G^{\tG}(\Theta_\pi)$ may be explicitly computed if $\pi$ is a stable sum
of standard modules.


title:
INTEGRAL sources: from obscured high mass X-ray binaries to supergiant
  fast X-ray transients

abstract:
  A new type of high-energy binary system has been revealed by the INTEGRAL
satellite. These sources are being unveiled by means of multi-wavelength
optical, near- and mid-infrared observations. Among these sources, two distinct
classes are appearing: the first one is constituted of intrinsically obscured
high-energy sources, of which IGR J16318-4848 seems to be the most extreme
example. The second one is populated by the so-called supergiant fast X-ray
transients, with IGR J17544-2619 being the archetype. We first give here a
general introduction on INTEGRAL sources, before reporting on multi-wavelength
optical to mid-infrared observations of a sample constituted of 21 INTEGRAL
sources. We show that in the case of the obscured sources our observations
suggest the presence of absorbing material (dust and/or cold gas) enshrouding
the whole binary system. We finally discuss the nature of these two different
types of sources, in the context of high energy binary systems, and give a
scenario of unification of all these different types of high energy sources,
based on their high energy properties.


title:
Variable Neighborhood Search for the University Lecturer-Student
  Assignment Problem

abstract:
  The paper presents a study of local search heuristics in general and variable
neighborhood search in particular for the resolution of an assignment problem
studied in the practical work of universities. Here, students have to be
assigned to scientific topics which are proposed and supported by members of
staff. The problem involves the optimization under given preferences of
students which may be expressed when applying for certain topics.
  It is possible to observe that variable neighborhood search leads to superior
results for the tested problem instances. One instance is taken from an actual
case, while others have been generated based on the real world data to support
the analysis with a deeper analysis.
  An extension of the problem has been formulated by integrating a second
objective function that simultaneously balances the workload of the members of
staff while maximizing utility of the students. The algorithmic approach has
been prototypically implemented in a computer system. One important aspect in
this context is the application of the research work to problems of other
scientific institutions, and therefore the provision of decision support
functionalities.


title:
Intrinsic photometric characterisation of stellar oscillations and
  granulation. Solar reference values and CoRoT response functions

abstract:
  Context: Measuring amplitudes of solar-like oscillations and the granulation
power spectral density constitute two promising sources of information to
improve our understanding and description of the convection in outer layers of
stars. However, different instruments, using different techniques and different
bandpasses, give measurements that cannot be directly compared to each other or
to theoretical values. Aims: In this work, we define simple response functions
to derive intrinsic oscillation amplitudes and granulation power densities,
from photometry measurements obtained with a specific instrument on a specific
star. Methods: We test this method on different photometry data sets obtained
on the Sun with two different instruments in three different bandpasses.
Results: We show that the results are in good agreement and we establish
reference intrinsic values for the Sun with photometry. We also compute the
response functions of the CoRoT instrument for a range of parameters
representative of the Main Sequence solar-like pulsators to be observed with
CoRoT. We show that these response functions can be conveniently described by
simple analytic functions of the effective temperature of the target star.


title:
Discrete Fourier analysis on fundamental domain of $A_d$ lattice and on
  simplex in $d$-variables

abstract:
  A discrete Fourier analysis on the fundamental domain $\Omega_d$ of the
$d$-dimensional lattice of type $A_d$ is studied, where $\Omega_2$ is the
regular hexagon and $\Omega_3$ is the rhombic dodecahedron, and analogous
results on $d$-dimensional simplex are derived by considering invariant and
anti-invariant elements. Our main results include Fourier analysis in
trigonometric functions, interpolation and cubature formulas on these domains.
In particular, a trigonometric Lagrange interpolation on the simplex is shown
to satisfy an explicit compact formula and the Lebesgue constant of the
interpolation is shown to be in the order of $(\log n)^d$. The basic
trigonometric functions on the simplex can be identified with Chebyshev
polynomials in several variables already appeared in literature. We study
common zeros of these polynomials and show that they are nodes for a family of
Gaussian cubature formulas, which provides only the second known example of
such formulas.


title:
Effect of pressure on the structural phase transition and
  superconductivity in (B$_{1-x}K_x)Fe_2As_2 (x = 0 and 0.45) and SrFe_2As_2
  single crystals

abstract:
  The effects of pressure up to $\sim 20$ kbar, on the structural phase
transition of SrFe$_2$As$_2$ and lightly Sn-doped BaFe$_2$As$_2$, as well as on
the superconducting transition temperature and upper critical field of
(Ba$_{0.55}$K$_{0.45}$)Fe$_2$As$_2$ single crystals have been studied. All the
transition temperatures decrease with pressure in an almost linear fashion.
Under pressure, the upper critical field curve, $H_{c2}(T)$, for
(Ba$_{0.55}$K$_{0.45}$)Fe$_2$As$_2$ shifts down in temperature to follow the
zero field $T_c$ with very little change in slope. Composite $P - T$ phase
diagrams for three parent compounds, AFe$_2$As$_2$ (A = Ba, Sr, Ca), are
constructed and appear to be remarkably similar: (i) having a structural
(antiferromagnetic) phase transition line with a negative slope and (ii)
showing signs of the emerging superconducting state at intermediate pressures.


title:
Impact of Context-Rich, Multifaceted Problems on Students' Attitudes
  Towards Problem-Solving

abstract:
  Most students struggle when faced with complex and ill-structured tasks
because the strategies taught in schools and universities simply require
finding and applying the correct formulae or strategy to answer
well-structured, algorithmic problems. For students to develop their ability to
solve ill-structured problems, they must first believe that standardized
procedural approaches will not always be sufficient for solving ill-structured
engineering and scientific challenges. In this paper we document the range of
beliefs university students have about problem-solving. Students enrolled in a
physics course submitted a written reflection both at the start and the end of
the course on how they solve problems. We coded approximately 500 of these
reflections for the presence of different problem-solving approaches. At the
start of the semester over 50% of the students mention in written reflections
that they use Rolodex equation matching, i.e. they solve problems by searching
for equations that have the same variables as the knowns and unknowns. We then
describe the extent to which students' beliefs about physics problem-solving
change due to their experience throughout a semester with context-rich,
multifaceted problems. The frequency of strategies such as the Rolodex method
reduces only slightly by the end of the semester. However, there is an increase
in students describing more expansive strategies within their reflections. In
particular there is a large increase in describing the use of diagrams, and
thinking about concepts first. Hence the use of context-rich, multi-faceted
problems positively impacts students' attitude towards problem-solving.


title:
Microwave-Driven Atoms: From Anderson Localization to Einstein's
  Photoeffect

abstract:
  We study the counterpart of Anderson localization in driven one-electron
Rydberg atoms. By changing the initial Rydberg state at fixed microwave
frequency and interaction time, we numerically monitor the crossover from
Anderson localization to the photo effect in the atomic ionization signal.


title: Brane Vector Dynamics from Embedding Geometry

abstract:
  A Kaluza-Klein decomposition of higher dimensional gravity is performed in
the flexible brane world scenario and the properties of the extra vectors
resulting from this decomposition are explored. These vectors become massive
due to a gravitational Higgs mechanism in which the brane oscillation
Nambu-Goldstone bosons become the longitudinal component of the vector fields.
The vector mass is found to be proportional to the exponential of the vacuum
expectation value of the radion (dilaton) field and as such its magnitude is
model dependent. Using the structure of the embedding geometry, the couplings
of these vectors to the Standard Model, including those resulting from the
extrinsic curvature, are deduced. As an example, we show that for 5D space-time
the geometry of the bulk-brane world, either intrinsic or extrinsic, only
depends on the extra vector and the 4D graviton. The connection between the
embedding geometry and coset construction by non-linear realization is also
presented.


title: Practical cosmology and cosmological physics

abstract:
  We present a summary of the International conference "Problems of practical
cosmology", held at Russian Geographical Society, 23-27 June 2008,
St.-Petersburg, Russia, where original reports were offered for discussion of
new developments in modern cosmological physics, including the large scale
structure of the Universe, the evolution of galaxies, cosmological effects in
the local stellar systems, gravity physics for cosmology, cosmological models,
and crucial observational tests of rival world models. The term "Practical
Cosmology" was introduced by Allan Sandage in 1995 when he formulated "23
astronomical problems for the next three decades" at the conference on "Key
Problems in Astronomy and Astrophysics" held at Canary Islands. Now when the
first decade has passed, we can summarise the present situation in cosmological
physics emphasizing interesting hot problems that have arisen during the last
decade. Full texts of all reports are available at the website of the
conference.


title: Nonabelian D-branes, Open Strings, and Gauge Theory

abstract:
  There is a subtle difference between the open string dynamics determined by
the original dual resonance models and that determined by D-brane constructions
within critical closed string theory. For instance, in contrast to the former,
the latter have massless scalars in addition to the massless gluon shared by
both. We introduce and explain the concept of nonabelian D-branes which
illuminates this distinction. We employ this concept to offer new possibilities
for string duals for large N QCD (pure Yang-Mills gauge theory).


title: On the Lie-algebraic origin of metric 3-algebras

abstract:
  Since the pioneering work of Bagger-Lambert and Gustavsson, there has been a
proliferation of three-dimensional superconformal Chern-Simons theories whose
main ingredient is a metric 3-algebra. On the other hand, many of these
theories have been shown to allow for a reformulation in terms of standard
gauge theory coupled to matter, where the 3-algebra does not appear explicitly.
In this paper we reconcile these two sets of results by pointing out the
Lie-algebraic origin of some metric 3-algebras, including those which have
already appeared in three-dimensional superconformal Chern-Simons theories.
More precisely, we show that the real 3-algebras of Cherkis-Saemann, which
include the metric Lie 3-algebras as a special case, and the hermitian
3-algebras of Bagger-Lambert can be constructed from pairs consisting of a
metric real Lie algebra and a faithful (real or complex, respectively) unitary
representation. This construction generalises and we will see how to construct
many kinds of metric 3-algebras from pairs consisting of a real metric Lie
algebra and a faithful (real, complex or quaternionic) unitary representation.
In the real case, these 3-algebras are precisely the Cherkis-Saemann algebras,
which are then completely characterised in terms of this data. In the complex
and quaternionic cases, they constitute generalisations of the Bagger-Lambert
hermitian 3-algebras and anti-Lie triple systems, respectively, which underlie
N=6 and N=5 superconformal Chern-Simons theories, respectively. In the process
we rederive the relation between certain types of complex 3-algebras and metric
Lie superalgebras.


title: Spectrophotometry with Hectospec, the MMT's Fiber-Fed Spectrograph

abstract:
  We describe techniques for photometric calibration of optical spectra
obtained with the MMT's fiber-fed spectrograph, Hectospec. The atmospheric
dispersion compensation prisms built into the MMT's f/5 wide field corrector
effectively eliminate errors due to differential refraction, and simplify the
calibration procedure. The procedures that we describe here are applicable to
all 220,000+ spectra obtained to date with Hectospec because the instrument
response is stable. We estimate the internal error in the Hectospec
measurements by comparing duplicate measurements of $\sim$1500 galaxies. For a
sample of 400 galaxies in the Smithsonian Hectospec Lensing Survey (SHELS) with
a median z=0.10, we compare line and continuum fluxes measured by Hectospec
through a 1.5 arcsec diameter optical fiber with those measured by the Sloan
Digital Sky Survey (SDSS) through a 3 arcsec diameter optical fiber. Agreement
of the [OII] and H alpha SHELS and SDSS line fluxes, after scaling by the R
band flux in the different apertures, suggests that the spatial variation in
star formation rates over a 1.5 to 3 kpc radial scale is small. The median
ratio of the Hectospec and SDSS spectra, smoothed over 100 Angstrom scales, is
remarkably constant to ~5% over the range of 3850 to 8000 Angstroms. Offsets in
the ratio of the median [OII] and H alpha fluxes, the equivalent width of H
delta and the continuum index d4000 are a few percent, small compared with
other sources of scatter.


title: Concordance invariants from higher order covers

abstract:
  We generalize the Manolescu-Owens smooth concordance invariant delta(K) of
knots K in the 3-sphere to invariants delta_{p^n}(K) obtained by considering
covers of order p^n, with p prime. Our main result shows that for any odd prime
p, the direct sum of delta_{p^n} as n ranges through the natural numbers,
yields a homomorphism of infinite rank from the smooth concordance group to
Z^\infty. We also show that unlike delta, these new invariants typically are
not multiples of the knot signature, even for alternating knots. A significant
portion of the article is devoted to exploring examples.


title: Well-posedness for the 1D Zakharov-Rubenchik system

abstract:
  Local and global well-posedness results are established for the initial value
problem associated to the 1D Zakharov-Rubenchik system. We show that our
results are sharp in some situations by proving Ill-posedness results
otherwise. The global results allow us to study the norm growth of solutions
corresponding to the Schrodinger equation term. We use ideas recently
introduced to study the classical Zakharov systems.


title:
Temperature measurements of a Bose--Einstein condensate by
  ultra--intense light pulses

abstract:
  Experimentally the temperature in a Bose--Einstein condensate is always
deduced resorting to the comparison between the Maxwell--Boltzmann velocity
distribution function and the density profile in momentum space. Though a
successful method it is an approximation, since it also implies the use of
classical statistical mechanics at temperatures close to the condensation
temperature where quantal effects play a relevant role. The present work puts
forward a new method in which we use an ultra--intense light pulse and a
nonlinear optical material as detectors for differences in times--of--flight.
This experimental value shall be compared against the result here calculated,
using the Bose--Einstein distribution function, which is a
temperature--dependent variable, and in this way the temperature of the
condensate is obtained.


title: The topology of Birkhoff varieties

abstract:
  Our main theorem is that the inclusion of a Birkhoff variety in the affine
Grassmannian is a homotopy equivalence. We also construct analogues of tubular
neighborhoods for Birkhoff and Schubert varieties. We include some observations
on torus-equivariant cohomology.


title: Efficient Power Spectrum Estimation for High Resolution CMB Maps

abstract:
  Estimation of the angular power spectrum of the Cosmic Microwave Background
(CMB) on a small patch of sky is usually plagued by serious spectral leakage,
specially when the map has a hard edge. Even on a full sky map, point source
masks can alias power from large scales to small scales producing excess
variance at high multipoles. We describe a new fast, simple and local method
for estimation of power spectra on small patches of the sky that minimizes
spectral leakage and reduces the variance of the spectral estimate. For
example, when compared with the standard uniform sampling approach on a 8
degree X 8 degree patch of the sky with 2% area masked due to point sources,
our estimator halves the errorbars at l=2000 and achieves a more than fourfold
reduction in errorbars at l=3500. Thus, a properly analyzed experiment will
have errorbars at l=3500 equivalent to those of an experiment analyzed with the
now standard technique with ~ 16-25 times the integration time.


title: Reparameterization Invariant Collinear Operators

abstract:
  In constructing collinear operators, which describe the production of
energetic jets or energetic hadrons, important constraints are provided by
reparameterization invariance (RPI). RPI encodes Lorentz invariance in a power
expansion about a collinear direction, and connects the Wilson coefficients of
operators at different orders in this expansion to all orders in alphas. We
construct reparameterization invariant collinear objects. The expansion of
operators built from these objects provides an efficient way of deriving RPI
relations and finding a minimal basis of operators, particularly when one has
an observable with multiple collinear directions and/or soft particles.
Complete basis of operators are constructed for pure glue currents at twist-4,
and for operators involving multiple collinear directions, including those
appearing in e+e- -> 3 jets, and for pp-> 2 jets initiated via gluon-fusion.


title: Low R_v from circumstellar dust around supernovae

abstract:
  The effective extinction law for supernovae surrounded by circumstellar dust
is examined by Monte-Carlo simulations. Grains with light scattering properties
as for interstellar dust in the Milky-Way (MW) or the Large Magellanic Clouds
(LMC), but surrounding the explosion site would cause a semi-diffusive
propagation of light up to the edge of the dust shell. Multiple scattering of
photons predominantly attenuates photons with shorter wavelengths, thus
steepening the effective extinction law as compared to the case of single
scattering in the interstellar medium. Our simulations yield typical values for
the total to selective extinction ratio $R_V\sim 1.5-2.5$, as seen in recent
studies of Type Ia supernova colors, with further stiffening differential
extinction toward the near-UV.


title:
An improved limit on the neutrino mass with CMB and redshift-dependent
  halo bias-mass relations from SDSS, DEEP2, and Lyman-Break Galaxies

abstract:
  We use measurements of luminosity-dependent galaxy bias at several different
redshifts, SDSS at $z=0.05$, DEEP2 at $z=1$ and LBGs at $z=3.8$, combined with
WMAP five-year cosmic microwave background anisotropy data and SDSS Red
Luminous Galaxy survey three-dimensional clustering power spectrum to put
constraints on cosmological parameters. Fitting this combined dataset, we show
that the luminosity-dependent bias data that probe the relation between halo
bias and halo mass and its redshift evolution are very sensitive to sum of the
neutrino masses: in particular we obtain the upper limit of $\sum
m_{\nu}<0.28$eV at the 95% confidence level for a $\Lambda CDM + m_{\nu}$
model, with a $\sigma_8$ equal to $\sigma_8=0.759\pm0.025$ (1$\sigma$). When we
allow the dark energy equation of state parameter $w$ to vary we find
$w=-1.30\pm0.19$ for a general $wCDM+m_{\nu}$ model with the 95% confidence
level upper limit on the neutrino masses at $\sum m_{\nu}<0.59$eV. The
constraint on the dark energy equation of state further improves to
$w=-1.125\pm0.092$ when using also ACBAR and supernovae Union data, in addition
to above, with a prior on the Hubble constant from the Hubble Space Telescope.


title:
Destruction of Molecular Gas Reservoirs in Early-Type Galaxies by Active
  Galactic Nucleus Feedback

abstract:
  Residual star formation at late times in early-type galaxies and their
progenitors must be suppressed in order to explain the population of red,
passively evolving systems we see today. Likewise, residual or newly accreted
reservoirs of molecular gas that are fuelling star formation must be destroyed.
This suppression of star formation in early-type galaxies is now commonly
attributed to AGN feedback wherein the reservoir of gas is heated and expelled
during a phase of accretion onto the central supermassive black hole. However,
direct observational evidence for a link between the destruction of this
molecular gas and an AGN phase has been missing so far. We present new
mm-wavelength observations from the IRAM 30m telescope of a sample of low
redshift SDSS early-type galaxies currently undergoing this process of
quenching of late-time star formation. Our observations show that the
disappearance of the molecular gas coincides within less than 100 Myr with the
onset of accretion onto the black hole and is too rapid to be due to star
formation alone. Since our sample galaxies are not associated to powerful
quasar activity or radio jets, we conclude that low-luminosity AGN episodes are
sufficient to suppress residual star formation in early-type galaxies. This
`suppression mode' of AGN feedback is very different from the `truncation mode'
linked to powerful quasar activity during early phases of galaxy formation.


title: Inflaton mass in the nuMSM inflation

abstract:
  We analyse the reheating in the modification of \nuMSM (Standard Model with
three right handed neutrinos with masses below the electroweak scale) where the
sterile neutrino providing the Dark Matter is generated in decays of the
additional inflaton field. We deduce that due to rather inefficient transfer of
energy from the inflaton to the Standard Model sector reheating tends to happen
at very low temperature, thus providing strict bounds on the coupling between
the inflaton and the Higgs particles. This in turn translates to the bound on
the inflaton mass, which appears to be very light 0.1 GeV <~ m_I <~ 10 GeV, or
slightly heavier then two Higgs masses 300 GeV <~ m_I <~ 1000 GeV.


title: F-theory, GUTs, and the Weak Scale

abstract:
  In this paper we study a deformation of gauge mediated supersymmetry breaking
in a class of local F-theory GUT models where the scale of supersymmetry
breaking determines the value of the mu term. Geometrically correlating these
two scales constrains the soft SUSY breaking parameters of the MSSM. In this
scenario, the hidden SUSY breaking sector involves an anomalous U(1)
Peccei-Quinn symmetry which forbids bare mu and B mu terms. This sector
typically breaks supersymmetry at the desired range of energy scales through a
simple stringy hybrid of a Fayet and Polonyi model. A variant of the
Giudice-Masiero mechanism generates the value mu ~ 10^2 - 10^3 GeV when the
hidden sector scale of supersymmetry breaking is F^(1/2) ~ 10^(8.5) GeV.
Further, the B mu problem is solved due to the mild hierarchy between the GUT
scale and Planck scale. These models relate SUSY breaking with the QCD axion,
and solve the strong CP problem through an axion with decay constant f_a ~
M_(GUT) * mu / L, where L ~ 10^5 GeV is the characteristic scale of gaugino
mass unification in gauge mediated models, and the ratio \mu / L ~
M_(GUT)/M_(pl) ~ 10^(-3). We find f_a ~ 10^12 GeV, which is near the high end
of the phenomenologically viable window. Here, the axino is the goldstino mode
which is eaten by the gravitino. The gravitino is the LSP with a mass of about
10^1 - 10^2 MeV, and a bino-like neutralino is (typically) the NLSP with mass
of about 10^2 - 10^3 GeV. Compatibility with electroweak symmetry breaking also
determines the value of tan(beta) ~ 30 +/- 7.


title: On different ways to quantize Soft-Collinear Effective Theory

abstract:
  Collinear fields in soft collinear effective theory (SCET) can be made
invariant under collinear gauge transformations by multiplying them with
collinear Wilson lines. We discuss how we can quantize SCET directly in terms
of these gauge invariant fields, allowing to directly calculate S matrix
elements using the gauge invariant collinear fields. We also show how for each
collinear direction SCET can be written in terms of fields whose interactions
are given by the usual QCD Lagrangian, and how external operators coupling
these different directions can be constructed.


title: Stochastic tunneling for strongly non-Gaussian inflationary theories

abstract:
  We reconsider the dynamics of stochastic or thermal tunneling in theories
like Dirac-Born-Infeld inflation that have non-minimal kinetic terms and, as a
result, strongly non-Gaussian perturbations. We first describe a local
description of the tunneling process which gives results consistent with the
standard Hawking-Moss tunneling. This result is under perturbative control as
long as the fluctuation determinant is well approximated by a one-loop
integral. We then move to a global description, using the methodology of
stochastic inflation and the in-in path integral formalism. This approach shows
clearly that the tunneling process becomes strongly coupled whenever the sound
speed of the tunneling trajectory departs sufficiently from unity. We argue
that these two very different perspectives are nevertheless consistent, and may
imply the existence of a simple resummation of the strongly coupled
interactions of the field.


title:
The Co-Evolution of Galaxies and Black Holes: Current Status and Future
  Prospects

abstract:
  I begin by summarizing the evidence that there is a close relationship
between the evolution of galaxies and supermassive black holes. They evidently
share a common fuel source, and feedback from the black hole may be needed to
suppress over-cooling in massive galaxies. I then review what we know about the
co-evolution of galaxies and black holes in the modern universe (z < 1). We now
have a good documentation of which black holes are growing (the lower mass
ones), where they are growing (in the less massive early-type galaxies), and
how this growth is related in a statistical sense to star formation in the
central region of the galaxy. The opportunity in the next decade will be to use
the new observatories to undertake ambitious programs of 3-D imaging
spectroscopy of the stars and gas in order to understand the actual
astrophysical processes that produce the demographics we observe. At high
redshift (z > 2) the most massive black holes and the progenitors of the most
massive galaxies are forming. Here, we currently have a tantalizing but
fragmented view of their co-evolution. In the next decade the huge increase in
sensitivity and discovery power of our observatories will enable us to analyze
the large, complete samples we need to achieve robust and clear results.


title: Tropical descendant Gromov-Witten invariants

abstract:
  We define tropical Psi-classes on the moduli space of rational tropical
curves in R^2 and consider intersection products of Psi-classes and pull-backs
of evaluations on this space. We show a certain WDVV equation which is
sufficient to prove that tropical numbers of curves satisfying certain Psi- and
evaluation conditions are equal to the corresponding classical numbers. We
present an algorithm that generalizes Mikhalkin's lattice path algorithm and
counts rational plane tropical curves satisfying certain Psi- and evaluation
conditions.


title: Excitations of single-beauty hadrons

abstract:
  In this work we study the predominantly orbital and radial excitations of
hadrons containing a single heavy quark. We present meson and baryon mass
splittings and ratios of meson decay constants (e.g., $f_{B_s}/f_B$ and
$f_{B_s'}/f_{B_s}$) resulting from quenched and dynamical two-flavor
configurations. Light quarks are simulated using the chirally improved (CI)
lattice Dirac operator at valence masses as light as $M_\pi \approx 350$ MeV.
The heavy quark is approximated by a static propagator, appropriate for the $b$
quark on our lattices ($1/a \sim 1-2$ GeV). We also include some preliminary
calculations of the $O(1/m_Q^{})$ kinetic corrections to the states, showing,
in the process, a viable way of applying the variational method to three-point
functions involving excited states. We compare our results with recent
experimental findings.


title: Long Wavelength Correlations and Transport in a Marginal Fermi Liquid

abstract:
  Marginal Fermi liquid was originally introduced as a phenomenological
description of the cuprates in a part of the metallic doping range which
appears to be governed by fluctuations due to a quantum-critical point. An
essential result due to the form of the assumed fluctuation spectra is that the
large inelastic quasiparticle relaxation rate near the Fermi-surface is
proportional to the energy measured from the chemical potential,
$\tau_i^{-1}\propto\epsilon$. We present a microscopic long-wavelength
derivation of the hydrodynamic properties in such a situation by an extension
of the procedure that Eliashberg used for the derivation of the hydrodynamic
properties of a Landau-Fermi-liquid. In particular, the density-density and the
current-current correlations and the relation between the two are derived, and
the connection to microscopic calculations of the frequency dependence of the
optical conductivity with an additional fermi-liquid correction factor shown to
follow. The method used here may be necessary, quite generally, for the correct
hydrodynamic theory for any problem of quantum-critical fluctuations in
fermions.


title:
A Catalog of X-ray Point Sources from Two Megaseconds of Chandra
  Observations of the Galactic Center

abstract:
  We present a catalog of 9017 X-ray sources identified in Chandra observations
of a 2 by 0.8 degree field around the Galactic center. We increase the number
of known X-ray sources in the region by a factor of 2.5. The catalog
incorporates all of the ACIS-I observations as of 2007 August, which total 2.25
Msec of exposure. At the distance to the Galactic center (8 kpc), we are
sensitive to sources with luminosities >4e32 erg/s (0.5-8.0 keV; 90%
confidence) over an area of one square degree, and up to an order of magnitude
more sensitive in the deepest exposure (1.0 Msec) around Sgr A*. The positions
of 60% of our sources are accurate to <1" (95% confidence), and 20% have
positions accurate to <0.5". We search for variable sources, and find that 3%
exhibit flux variations within an observation, 10% exhibit variations from
observation-to-observation. We also find one source, CXOUGC J174622.7-285218,
with a periodic 1745 s signal (1.4% chance probability), which is probably a
magnetically-accreting cataclysmic variable. We compare the spatial
distribution of X-ray sources to a model for the stellar distribution, and find
2.8 sigma evidence for excesses in the numbers of X-ray sources in the region
of recent star formation encompassed by the Arches, Quintuplet, and Galactic
center star clusters. These excess sources are also seen in the luminosity
distribution of the X-ray sources, which is flatter near the Arches and
Quintuplet than elsewhere in the field. These excess point sources, along with
a similar longitudinal asymmetry in the distribution of diffuse iron emission
that has been reported by other authors, probably have their origin in the
young stars that are prominent at l~0.1 degree.


title:
The Mid-Infrared Extinction Law in the Ophiuchus, Perseus, and Serpens
  Molecular Clouds

abstract:
  We compute the mid-infrared extinction law from 3.6-24 microns in three
molecular clouds: Ophiuchus, Perseus, and Serpens, by combining data from the
"Cores to Disks" Spitzer Legacy Science program with deep JHKs imaging. Using a
new technique, we are able to calculate the line-of-sight extinction law
towards each background star in our fields. With these line-of-sight
measurements, we create, for the first time, maps of the chi-squared deviation
of the data from two extinction law models. Because our chi-squared maps have
the same spatial resolution as our extinction maps, we can directly observe the
changing extinction law as a function of the total column density. In the
Spitzer IRAC bands, 3.6-8 microns, we see evidence for grain growth. Below
$A_{K_s} = 0.5$, our extinction law is well-fit by the Weingartner & Draine
(2001) $R_V = 3.1$ diffuse interstellar medium dust model. As the extinction
increases, our law gradually flattens, and for $A_{K_s} >= 1$, the data are
more consistent with the Weingartner & Draine $R_V = 5.5$ model that uses
larger maximum dust grain sizes. At 24 microns, our extinction law is 2-4 times
higher than the values predicted by theoretical dust models, but is more
consistent with the observational results of Flaherty et al. (2007). Lastly,
from our chi-squared maps we identify a region in Perseus where the IRAC
extinction law is anomalously high considering its column density. A steeper
near-infrared extinction law than the one we have assumed may partially explain
the IRAC extinction law in this region.


title:
Auger-mediated radiative recombination in three-dimensional
  silicon/silicon-germanium nanostructures

abstract:
  In a semiconductor heterostructure with type II energy band alignment, the
spatial separation between electrons and holes slows down their radiative
recombination. With increasing excitation intensity, Auger recombination
quickly becomes the dominate recombination channel, and it produces carrier
ejection from the quantum well. Here, we show that in Si/SiGe three-dimensional
nanostructures, this efficient process facilitates the formation of an
electron-hole plasma (EHP) and/or electron-hole droplets (EHDs) in thin Si
barriers separating SiGe clusters. In contrast to conventional, strongly
temperature dependent and slow radiative carrier recombination in bulk Si, this
EHD/EHP luminescence in nanometer-thick Si layers is found to be nearly
temperature independent with radiative lifetime approaching 10^-8 s, which is
only slightly slower than that found in direct band gap III-V semiconductors.


title:
Prevalence of High X-ray Obscuring Columns among AGN that Host H$_2$O
  Masers

abstract:
  Of 104 AGN known to exhibit H$_2$O maser emission, X-ray data that enable
estimation of column densities, or lower limits, are available for 42.
Contributing to this, we report analysis of new and archival X-ray data for 8
galaxies and collation of values for three more. Maser emission is indicative
of large columns of cold gas, and in five of the eight new cases, maser spectra
point toward origins in accretion disks viewed close-to edge-on (a.k.a.
"disk-maser" systems). In these, we detect hard continuum and Fe K$\alpha$
emission with equivalent widths on the order of 1 keV, which is consistent with
Compton reflection, fluorescence by cold material, and obscuring columns $\ga
10^{24}$ cm$^{-2}$. Reviewing the full sample of 42, 95% exhibit N$_{\rm H}
>10^{23}$ cm$^{-2}$ and 60% exhibit N$_{\rm H} >10^{24}$ cm$^{-2}$. Half of
these are now recognized to be disk masers (up from 13); in this sub-sample,
which is likely to be more homogeneous vis-\'a-vis the origin of maser
emission, 76% exhibit N$_{\rm H} >10^{24}$ cm$^{-2}$. The probability of a
common parent distribution of columns for disk-masers and other AGN masers is
<3%. Because ground-based surveys of AGN to detect new disk masers are
relatively unbiased with respect to X-ray brightness and comparatively
inexpensive, they may also be efficient guides for the sensitive pointed X-ray
observations required to identify Compton-thick objects outside of shallow
surveys.


title: Dynamical Mean Field Study of The Dirac Liquid

abstract:
  Renormalization is one of the basic notions of condensed matter physics.
Based on the concept of renormalization, the Landau's {\em Fermi liquid} theory
has been able to explain, why despite the presence of Coulomb interactions, the
free electron theory works so well for simple metals with extended Fermi
surface (FS). The recent synthesis of graphene has provided the condensed
matter physicists with a low energy laboratory of Dirac fermions where instead
of a FS, one has two Fermi points. Many exciting phenomena in graphene can be
successfully interpreted in terms of free Dirac electrons. In this paper,
employing dynamical mean field theory (DMFT), we show that an interacting Dirac
sea is essentially an effective free Dirac theory. This observation suggests
the notion of {\em Dirac liquid} as a fixed point of interacting 2+1
dimensional Dirac fermions. We find one more fixed point at strong interactions
describing a Mott insulating state, and address the nature of semi-metal to
insulator (SMIT) transition in this system.


title:
Improved Measurement of Branching Fractions for pipi Transitions among
  Upsilon(nS)States

abstract:
  Using samples of (5.93 +/- 0.10) x 10^6 Upsilon(3S) decays and (9.11 +/-
0.14) x 10^6 Upsilon(2S) decays collected with the CLEO detector, we report
improved measurements of the branching fractions for the following five
transitions: B(Upsilon(3S)-->Upsilon(1S) pi^+ pi^-) = (4.46 +/- 0.01 +/-
0.13)%, B(Upsilon(2S)-->Upsilon(1S) pi^+ pi^-) = (18.02 +/- 0.02 +/- 0.61)%,
B(Upsilon(3S)-->Upsilon(1S) pi^0 pi^0) = (2.24 +/- 0.09 +/- 0.11)%,
B(Upsilon(2S)-->Upsilon(1S) pi^0 pi^0) = (8.43 +/- 0.16 +/- 0.42)% and
B(Upsilon(3S)-->Upsilon(2S) pi^0 pi^0) = (1.82 +/- 0.09 +/- 0.12)%. In each
case the first uncertainty reported is statistical, while the second is
systematic.


title:
Measurability of optimal transportation and strong coupling of
  martingale measures

abstract:
  We consider the optimal mass transportation problem in $\RR^d$ with
measurably parameterized marginals, for general cost functions and under
conditions ensuring the existence of a unique optimal transport map. We prove a
joint measurability result for this map, with respect to the space variable and
to the parameter. The proof needs to establish the measurability of some
set-valued mappings, related to the support of the optimal transference plans,
which we use to perform a suitable discrete approximation procedure. A
motivation is the construction of a strong coupling between orthogonal
martingale measures. By this we mean that, given a martingale measure, we
construct in the same probability space a second one with specified covariance
measure. This is done by pushing forward one martingale measure through a
predictable version of the optimal transport map between the covariance
measures. This coupling allows us to obtain quantitative estimates in terms of
the Wasserstein distance between those covariance measures.


title: R-symmetric gauge mediation

abstract:
  We present a version of Gauge Mediated Supersymmetry Breaking which preserves
an R-symmetry - the gauginos are Dirac particles, the A-terms are zero, and
there are four Higgs doublets. This offers an alternative way for gauginos to
acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and
Shih. We investigate the possibility of using R-symmetric gauge mediation to
realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz,
and Weiner.


title:
Solution of the nonstationary diffusion equation for interstitial
  impurity atoms by the method of Green functions

abstract:
  On the basis of the Green function method, analytical solutions of the
diffusion equation which describes nonstationary migration of nonequilibrium
interstitial impurity atoms have been derived. It is supposed that the initial
distribution of nonequilibrium impurity interstitials is formed due to ion
implantation and, therefore, is described by the Gaussian function. The
condition of the constant concentration of impurity interstitials (the
Dirichlet boundary condition) or reflecting boundary condition was imposed on
the surface of a semiconductor. The Dirichlet boundary condition was also
enforced for the concentration of impurity interstitials in the infinity, i.e.,
in the bulk of a semiconductor. On the basis of the solutions derived the
redistribution of ion-implanted boron in silicon substrate during
low-temperature thermal treatment has been simulated. The calculated profile of
boron atoms after annealing agrees well with experimental data. It means that
the analytical solutions derived can be used both for verifying the numerical
results and for modeling the long-range migration of nonequilibrium impurity
interstitials during low-temperature thermal treatments.


title: On Black Objects in Type IIA Superstring Theory on Calabi-Yau Manifolds

abstract:
  The compactification of type IIA superstring on n-dimensional Calabi-Yau
manifolds is discussed. In particular, a conjecture is given for type IIA
extremal p-dimensional black brane attractors corresponding to Ads_{p+2}\times
S^{8-2n-p} horizon geometries.


title: A vortex model for rotating compact objects

abstract:
  A rotating stationary solution of the vacuum Einstein equations with a
cosmological constant is exhibited which reduces to de Sitter's interior
cosmological solution when the angular momentum goes to zero. This solution is
locally isomorphic to de Sitter space, but as one approaches the axis of
rotation a conical event horizon appears that signals the appearance of a new
phase of space-time. This suggests that in reality rotating compact objects
have a vortex structure similar to that conjectured for rotating superfluid
droplets. In the limit of slow rotation the vortex core would be nearly
cylindrical and the space-time inside the core would be Godel-like. The
exterior space-time will resemble the Kerr solution for equatorial latitudes,
but significant deviations from Kerr are expected for polar latitudes.


title:
Anomalous circular polarization of magneto-photoluminescence from
  individual CdSe nanocrystals

abstract:
  We study the low-temperature magneto-photoluminescence (PL) from individual
CdSe nanocrystals. Nanocrystals having a small "bright" exciton fine structure
splitting ($<$0.5 meV) exhibit a conventional left- and right-circularly
polarized Zeeman PL doublet in applied magnetic fields. In contrast,
nanocrystals with large fine structure splitting ($>$1 meV) show an anomalous
magneto-PL polarization, wherein the lower-energy peak becomes circularly
polarized with increasing field, while the higher-energy peak remains linearly
polarized. This unusual behavior arises from strong mixing between the
absorbing and emitting bright exciton levels due to strong anisotropic exchange
interactions.


title: Extended Emission-Line Regions: Remnants of Quasar Superwinds?

abstract:
  We give an overview of our recent integral-field-unit spectroscopy of
luminous extended emission-line regions (EELRs) around low-redshift quasars,
including new observations of 5 fields. Previous work has shown that the most
luminous EELRs are found almost exclusively around steep-spectrum radio-loud
quasars, with apparently disordered global velocity fields, and little, if any,
morphological correlation with either the host-galaxy or the radio structure.
Our new observations confirm and expand these results. The EELRs often show
some clouds with velocities exceeding 500 km/s, ranging up to 1100 km/s, but
the velocity dispersions, with few exceptions, are in the 30-100 km/s range.
Emission-line ratios show that the EELRs are clearly photoionized by the
quasars. Masses of the EELRs range up to >10^10 Msun. Essentially all of the
EELRs show relatively low metallicities, and they are associated with quasars
that, in contrast to most, show similarly low metallicities in their broad-line
regions. The two objects in our sample that do not have classical double-lobed
radio morphologies (3C48, with a compact-steep-spectrum source; Mrk1014,
radio-quiet, but with a weak compact-steep-spectrum source) are the only ones
that appear to have recent star formation. While some of the less-luminous
EELRs may have other origins, the most likely explanation for the ones in our
sample is that they are examples of gas swept out of the host galaxy by a
large-solid-angle blast wave accompanying the production of the radio jets. The
triggering of the quasar activity is almost certainly the result of the merger
of a gas-rich galaxy with a massive, gas-poor galaxy hosting the supermassive
black hole.


title: Long-range correlation in sheared granular fluids

abstract:
  The spatial correlation function of the momentum density in the
three-dimensional dilute sheared granular fluids is theoretically investigated.
The existence of the long-range correlation is verified through both the
analytic calculation and the numerical simulation.


title: Determining the Energy Barrier for Decay out of Superdeformed Bands

abstract:
  An asymptotically exact quantum mechanical calculation of the matrix elements
for tunneling through an asymmetric barrier is combined with the two-state
statistical model for decay out of superdeformed bands to determine the energy
barrier (as a function of spin) separating the superdeformed and
normal-deformed wells for several nuclei in the 190 and 150 mass regions. The
spin-dependence of the barrier leading to sudden decay out is shown to be
consistent with the decrease of a centrifugal barrier with decreasing angular
momentum. Values of the barrier frequency in the two mass regions are
predicted.


title:
Bias-controlled sensitivity of ferromagnet/semiconductor electrical spin
  detectors

abstract:
  Using Fe/GaAs Schottky tunnel barriers as electrical spin detectors, we show
that the magnitude and sign of their spin-detection sensitivities can be widely
tuned with the voltage bias applied across the Fe/GaAs interface. Experiments
and theory establish that this tunability derives not just simply from the bias
dependence of the tunneling conductances $G_{\uparrow,\downarrow}$ (a property
of the interface), but also from the bias dependence of electric fields in the
semiconductor which can dramatically enhance or suppress spin-detection
sensitivities. Electrons in GaAs with fixed polarization can therefore be made
to induce either positive or negative voltage changes at spin detectors, and
some detector sensitivities can be enhanced over ten-fold compared to the usual
case of zero-bias spin detection.


title:
An example concerning the Theory of Levels for codimension-one
  foliations

abstract:
  We give an example of a codimension-one foliation which is transversely of
class C^1 and which does not satisfy the "Local Minimal Set" property.


title:
Light Pseudoscalar Higgs boson in Neutralino Decays in the
  Next-to-Minimal Supersymmetric Standard Model

abstract:
  We point out another important production channel of a light pseudoscalar
Higgs boson $a_1$ via the decays of neutralinos, including
$\widetilde{\chi}_{2,3}^0 \to \widetilde{\chi}_{1}^0 a_1$, in the framework of
the NMSSM. We scan the whole parameter space using the most up-to-date version
of NMHDECAY and search for regions where $B(\widetilde{\chi}_{2,3}^0 \to
\widetilde{\chi}_{1}^0 a_1) > 0.5$. If the gluino and squarks are light enough
for copious production of SUSY events at the LHC, there would be numerous
number of $\widetilde{\chi}_{2,3}^0$ in subsequent decays of gluinos and
squarks. Therefore, the production rates of $a_1$ via neutralino decays would
be more important than $h \to a_1 a_1$ and others. Potentially, the final state
is filled with many $\tau$ leptons, which can be reconstructed at the mass of
$a_1$. This is a clean, observable, and distinguishable signature for NMSSM.


title:
The Marginal Fermi Liquid - An Exact Derivation Based on Dirac's First
  Class Constraints Method

abstract:
  Dirac's method for constraints is used for solving the problem of exclusion
of double occupancy for Correlated Electrons. The constraints are enforced by
the pair operator
$Q(\vec{x})=\psi_{\downarrow}(\vec{x})\psi_{\uparrow}(\vec{x})$ which
annihilates the ground state $|\Psi^0>$. Away from half fillings the operator
$Q(\vec{x})$ is replaced by a set of $first$ $class$ Non-Abelian constraints
$Q^{(-)}_{\alpha}(\vec{x})$ restricted to negative energies. The propagator for
a single hole away from half fillings is determined by modified measure which
is a function of the time duration of the hole propagator. As a result: a) The
imaginary part of the self energy - is linear in the frequency. At large hole
concentrations a Fermi Liquid self energy is obtained. b) For the
Superconducting state the constraints generate an asymmetric spectrum
excitations between electrons and holes giving rise to an asymmetry tunneling
density of states.


title:
Geometrical and Physical Properties of Circumbinary Discs in Eccentric
  Stellar Binaries

abstract:
  In a previous work (Pichardo et al. 2005), we studied stable configurations
for circumstellar discs in eccentric binary systems. We searched for "invariant
loops": closed curves (analogous to stable periodic orbits in time-independent
potentials) that change shape with the binary orbital phase, as test particles
in them move under the influence of the binary potential. This approach allows
us to identify stable configurations when pressure forces are unimportant, and
dissipation acts only to prevent gas clouds from colliding with one another. We
now extend this work to study the main geometrical properties of circumbinary
discs. We have studied more than 100 cases with a range in eccentricity 0 .le.
e .le. 0.9, and mass ratio 0.1 .le. q .le. 0.9. Although gas dynamics may
impose further restrictions, our study sets lower stable bounds for the size of
the central hole in a simple and computationally cheap way, with a relation
that depends on the eccentricity and mass ratio of the central binary. We
extend our previous studies and focus on an important component of these
systems: circumbinary discs. The radii for stable orbits that can host gas in
circumbinary discs are sharply constrained as a function of the binary's
eccentricity. The circumbinary disc configurations are almost circular, with
eccentricity e_d < 0.15, but if the mass ratio is unequal the disk is offset
from the center of mass of the system. We compare our results with other
models, and with observations of specific systems like GG Tauri A, UY Aurigae,
HD 98800 B, and Fomalhaut, restricting the plausible parameters for the binary.


title: beta-family congruences and the f-invariant

abstract:
  In previous work, the authors have each introduced methods for studying the
2-line of the p-local Adams-Novikov spectral sequence in terms of the
arithmetic of modular forms. We give the precise relationship between the
congruences of modular forms introduced by the first author with the Q-spectrum
and the f-invariant of the second author. This relationship enables us to
refine the target group of the f-invariant in a way which makes it more
manageable for computations.


title: Supermassive Black Holes in Galactic Bulges

abstract:
  Growing evidence indicate supermassive black holes (SMBHs) in a mass range of
$M_{\rm BH}$$\sim 106-10^{10}M_{\odot}$ lurking in central stellar bulges of
galaxies.Extensive observations reveal fairly tight power laws of $M_{\rm BH}$
versus the mean stellar velocity dispersion $\sigma$ of the host stellar
bulge.Together with evidence for correlations between $M_{\rm BH}$ and other
properties of host bulges, the dynamic evolution of a bulge and the formation
of a central SMBH should be linked. In this Letter, we reproduce the empirical
$M_{\rm BH}-\sigma$ power laws based on our recent theoretical analyses (Lou &
Wang; Wang & Lou; Lou, Jiang & Jin) for a self-similar general polytropic
quasi-static dynamic evolution of bulges with self-gravity and spherical
symmetry and present a sensible criterion of forming a central SMBH. The key
result is $M_{\rm BH}={\cal L}\sigma^{1/(1-n)}$ where $2/3<n<1$ and ${\cal L}$
is a proportional coefficient characteristic of different classes of host
bulges. By fitting and comparing several empirical $M_{\rm BH}-\sigma$ power
laws, we conclude that SMBHs and galactic bulges grow and evolve in a coeval
manner and most likely there exist several classes of galactic bulge systems in
quasi-static self-similar evolution and that to mix them together can lead to
an unrealistic fitting. Based on our bulge-SMBH model, we provide explanations
for intrinsic scatter in the relation and a unified scenario for the formation
and evolution of SMBHs in different classes of host bulges.


title:
Self-organization of feedforward structure and entrainment in excitatory
  neural networks with spike-timing-dependent plasticity

abstract:
  Spike-timing dependent plasticity (STDP) is an organizing principle of
biological neural networks. While synchronous firing of neurons is considered
to be an important functional block in the brain, how STDP shapes neural
networks possibly toward synchrony is not entirely clear. We examine relations
between STDP and synchronous firing in spontaneously firing neural populations.
Using coupled heterogeneous phase oscillators placed on initial networks, we
show numerically that STDP prunes some synapses and promotes formation of a
feedforward network. Eventually a pacemaker, which is the neuron with the
fastest inherent frequency in our numerical simulations, emerges at the root of
the feedforward network. In each oscillatory cycle, a packet of neural activity
is propagated from the pacemaker to downstream neurons along layers of the
feedforward network. This event occurs above a clear-cut threshold value of the
initial synaptic weight. Below the threshold, neurons are self-organized into
separate clusters each of which is a feedforward network.


title: On the generalised Ritt problem as a computational problem

abstract:
  The Ritt problem asks if there is an algorithm that tells whether one prime
differential ideal is contained in another one if both are given by their
characteristic sets. We give several equivalent formulations of this problem.
In particular, we show that it is equivalent to testing if a differential
polynomial is a zero divisor modulo a radical differential ideal. The technique
used in the proof of equivalence yields algorithms for computing a canonical
decomposition of a radical differential ideal into prime components and a
canonical generating set of a radical differential ideal. Both proposed
representations of a radical differential ideal are independent of the given
set of generators and can be made independent of the ranking.


title: Continuous extension of arithmetic volumes

abstract:
  This paper is the sequel of the paper "Continuity of volumes on arithmetic
varieties", in which we established the arithmetic volume function of smooth
hermitian Q-invertible sheaves and proved its continuity. The continuity of the
volume function has a lot of applications as treated in the paper as above. In
this paper, we would like to consider its continuous extension over R.


title: Charged rotating dilaton black strings in AdS spaces

abstract:
  We derive a class of charged rotating dilaton black string solutions in the
background of anti-de-Sitter spaces with an appropriate combination of three
Liouville-type dilaton potentials. We also present the suitable counterterm
which removes the divergences of the action in the presence of dilaton
potential. The solutions are analyzed and their thermodynamics is discussed by
using the counterterm method.


title: Higher dimensional slowly rotating dilaton black holes in AdS spacetime

abstract:
  In this paper, with an appropriate combination of three Liouville-type
dilaton potentials, we obtain the higher dimensional charged slowly rotating
dilaton black hole solution for asymptotically anti-de Sitter spacetime. The
angular momentum and the gyromagnetic ratio of such a black hole are determined
for the arbitrary values of the dilaton coupling constant. It is shown that the
dilaton field modifies the gyromagnetic ratio of the rotating dilaton black
holes.


title: Managing Varying Worst Case Execution Times on DVS Platforms

abstract:
  Energy efficient real-time task scheduling attracted a lot of attention in
the past decade. Most of the time, deterministic execution lengths for tasks
were considered, but this model fits less and less with the reality, especially
with the increasing number of multimedia applications. It's why a lot of
research is starting to consider stochastic models, where execution times are
only known stochastically. However, authors consider that they have a pretty
much precise knowledge about the properties of the system, especially regarding
to the worst case execution time (or worst case execution cycles, WCEC).
  In this work, we try to relax this hypothesis, and assume that the WCEC can
vary. We propose miscellaneous methods to react to such a situation, and give
many simulation results attesting that with a small effort, we can provide very
good results, allowing to keep a low deadline miss rate as well as an energy
consumption similar to clairvoyant algorithms.


title:
Doping dependence of upper critical field and Hall resistivity in
  LaFeAsO1-xFx

abstract:
  The electrical resistivity (Rxx) and Hall resistivity (Rxy) of LaFeAsO1-xFx
have been measured over a wide fluorine doping range 0 =< x =< 0.14 using 60 T
pulsed magnets. While the superconducting phase diagram (Tc, x) displays the
classic dome-shaped structure, we find that the resistive upper critical field
(Hc2) increases monotonically with decreasing fluorine concentration, with the
largest Hc2 >= 75 T for x = 0.05. This is reminiscent of the composition
dependence in high-Tc cuprates and might correlate with opening of a pseudo-gap
in the underdoped region. Further, the temperature dependence of Hc2(T) for
superconducting samples can be understood in terms of multi-band
superconductivity. Rxy data for non-superconducting samples show non-linear
field dependence, which is also consistent with a multi-carrier scenario.


title:
The NLO corrections of $H_{TC} \Pi ^0$and $\Pi ^ + \Pi ^ - $ pair
  production at the ILC in the TC2 model

abstract:
  As well known, if the Higgs boson were not observed at LHC, the technicolor
model would be the most favorable candidate responsible for the symmetry
breaking. To overcome some defects in the previous model, some extended
versions have been proposed. In the TC2 model typical signature is existence of
heavy $H_{TC}$ and technipion $\Pi$. A direct proof of validity of the model is
to produce them at accelerator. Thus we study the production rates of $ e^ + e^
- \to H_{TC} \Pi ^0 $ and $e^ + e^ - \to \Pi ^ + \Pi ^ -$ at ILC in the
topcolor-assisted technicolor (TC2) model. In fact, there is a flood of models
belonging to new physics which can result in products with characteristics
similar to $H_{TC}+\Pi$ of the TC2 model. Therefore to distinguish this model
from others one may need to investigate some details by calculating the cross
section to NLO. We indeed find that the NLO corrections are significant, namely
the ratio $\delta \equiv (\sigma_{NLO} - \sigma_{LO})/\sigma_{LO} $ in $ e^ +
e^ - \to H_{TC} \Pi ^0 $ exceeds 100% within a plausible parameter space.


title: On adaptive stratification

abstract:
  This paper investigates the use of stratified sampling as a variance
reduction technique for approximating integrals over large dimensional spaces.
The accuracy of this method critically depends on the choice of the space
partition, the strata, which should be ideally fitted to thesubsets where the
functions to integrate is nearly constant, and on the allocation of the number
of samples within each strata. When the dimension is large and the function to
integrate is complex, finding such partitions and allocating the sample is a
highly non-trivial problem. In this work, we investigate a novel method to
improve the efficiency of the estimator "on the fly", by jointly sampling and
adapting the strata and the allocation within the strata. The accuracy of
estimators when this method is used is examined in detail, in the so-called
asymptotic regime (i.e. when both the number of samples and the number of
strata are large). We illustrate the use of the method for the computation of
the price of path-dependent options in models with both constant and stochastic
volatility. The use of this adaptive technique yields variance reduction by
factors sometimes larger than 1000 compared to classical Monte Carlo
estimators.


title: On the equivariant cohomology of subvarieties of a B-regular variety

abstract:
  By a $B$-regular variety, we mean a smooth projective variety over $C$
admitting an algebraic action of the upper triangular Borel subgroup $B \subset
SL_2(C)$ such that the unipotent radical in $B$ has a unique fixed point. A
result of M. Brion and the first author describes the equivariant cohomology
algebra (over $C$) of a $B$-regular variety $X$ as the coordinate ring of a
remarkable affine curve in $X \times P^1$. The main result of this paper uses
this fact to classify the $B$-invariant subvarieties $Y$ of a $B$-regular
variety $X$ for which the restriction map $i_Y:H^*(X) \to H^*(Y)$ is
surjective.


title: Baryonium in Confining Gauge Theories

abstract:
  We show a new class of embedding solutions of D5 brane, which wraps on $S^5$
in the AdS${}_5\times S^5$ space-time and contains fundamental strings as U(1)
flux to form a baryon vertex. The new solution given here is different from the
baryon vertex since it consists of two same side (north or south) poles of
$S^5$ as cusps, which are put on different points in our three dimensional
space. This implies that the same magnitude of electric displacement exists at
each cusp, but their orientations are opposite due to the flux number
conservation. This configuration is therefore regarded as a D5-$\bar{D5}$ bound
state, and we propose this as the vertex of a baryonium state, which is made of
a baryon and an anti-baryon. By attaching quarks and anti-quarks to the two
cusps of this vertex, it is possible to construct a realistic baryonium.


title: Derivation of evolutionary payoffs from observable behavior

abstract:
  Interpretation of animal behavior, especially as cooperative or selfish, is a
challenge for evolutionary theory. Strategy of a competition should follow from
corresponding Darwinian payoffs for the available behavioral options. The
payoffs and decision making processes, however, are difficult to observe and
quantify. Here we present a general method for the derivation of evolutionary
payoffs from observable statistics of interactions. The method is applied to
combat of male bowl and doily spiders, to predator inspection by sticklebacks
and to territorial defense by lions, demonstrating animal behavior as a new
type of game theoretical equilibrium. Games animals play may be derived
unequivocally from their observable behavior, the reconstruction, however, can
be subjected to fundamental limitations due to our inability to observe all
information exchange mechanisms (communication).


title: Fractality feature in oil price fluctuations

abstract:
  The scaling properties of oil price fluctuations are described as a
non-stationary stochastic process realized by a time series of finite length.
An original model is used to extract the scaling exponent of the fluctuation
functions within a non-stationary process formulation. It is shown that, when
returns are measured over intervals less than 10 days, the Probability Density
Functions (PDFs) exhibit self-similarity and monoscaling, in contrast to the
multifractal behavior of the PDFs at macro-scales (typically larger than one
month). We find that the time evolution of the distributions are well fitted by
a Levy distribution law at micro-scales. The relevance of a Levy distribution
is made plausible by a simple model of nonlinear transfer


title:
Quasinormal modes of RN black hole space time with cosmic string in a
  Dirac field

abstract:
  We evaluate quasinormal mode frequencies for RN black hole space times with
cosmic string perturbed by a massless Dirac field, using P\"{o}schl-Teller
potential method. We find that only in the case of RN black hole having small
charge, the effect due to cosmic string will dominate when perturbed by a
negatively charged Dirac field, but if we are perturbing with positively
charged Dirac field decay will be less in the case of black hole having cosmic
string compared to the RN black hole without string


title: Vertex Degree of Random Intersection Graph

abstract:
  A random intersection graph is constructed by independently assigning a
subset of a given set of objects $W,$ to each vertex of the vertex set $V$ of a
simple graph $G.$ There is an edge between two vertices of $V,$ iff their
respective subsets(in $W$,) have at least one common element. The strong
threshold for the connectivity between any two arbitrary vertices of vertex set
$V,$ is derived. Also we determine the almost sure probability bounds for the
vertex degree of a typical vertex of graph $G.$


title: A Strong threshold for the size of random caps to cover a sphere

abstract:
  In this article, we consider `$N$'spherical caps of area $4\pi p$ were
uniformly distributed over the surface of a unit sphere. We are giving the
strong threshold function for the size of random caps to cover the surface of a
unit sphere. We have shown that for large $N,$ if $\frac{Np}{\log\:N} > 1/2$
the surface of sphere is completely covered by the $N$ caps almost surely, and
if $\frac{Np}{\log\:N} \leq 1/2$ a partition of the surface of sphere is
remains uncovered by the $N$ caps almost surely.


title: Number of Edges in Random Intersection Graph on Surface of a Sphere

abstract:
  In this article, we consider `$N$'spherical caps of area $4\pi p$ were
uniformly distributed over the surface of a unit sphere. We study the random
intersection graph $G_N$ constructed by these caps. We prove that for $p =
\frac{c}{N^{\al}},\:c >0$ and $\al >2,$ the number of edges in graph $G_N$
follow the Poisson distribution. Also we derive the strong law results for the
number of isolated vertices in $G_N$: for $p = \frac{c}{N^{\al}},\:c >0$ for
$\al < 1,$ there is no isolated vertex in $G_N$ almost surely i.e., there are
atleast $N/2$ edges in $G_N$ and for $\al >3,$ every vertex in $G_N$ is
isolated i.e., there is no edge in edge set $\cE_N.$


title: Bialgebra structures of 2-associative algebras

abstract:
  This work is devoted to study new bialgebra structures related to
2-associative algebras. A 2-associative algebra is a vector space equipped with
two associative multiplications. We discuss the notions of 2-associative
bialgebras, 2-bialgebras and 2-2-bialgebras. The first structure was revealed
by J.-L. Loday and M. Ronco in an analogue of a Cartier-Milnor-Moore theorem,
the second was suggested by Loday and the third is a variation of the second
one. The main results of this paper are the construction of 2-associative
bialgebras, 2-bialgebras and 2-2-bialgebras starting from an associative
algebra and the classification of these structures in low dimensions.


title:
Strong decays $\Sigma^{*} \to\Sigma\pi,\Lambda \pi$ and related strong
  coupling constant

abstract:
  In this article, we calculate the strong coupling constant $g$ among the
decuplet baryons, the octet baryons and the pseudoscalar mesons in the heavy
baryon chiral perturbation theory with the light-cone QCD sum rules, and study
the strong decays $\Sigma^* \to \Lambda \pi,\Sigma \pi$. The numerical value of
the strong coupling constant $g$ is consistent with our previous calculation,
the central values lead to small SU(3) breaking effects, less than 6%; and no
definitive conclusion can be drawn due to the large uncertainties.


title:
Transport properties in network models with perfectly conducting
  channels

abstract:
  We study the transport properties of disordered electron systems that contain
perfectly conducting channels. Two quantum network models that belong to
different universality classes, unitary and symplectic, are simulated
numerically. The perfectly conducting channel in the unitary class can be
realized in zigzag graphene nano-ribbons and that in the symplectic class is
known to appear in metallic carbon nanotubes. The existence of a perfectly
conducting channel leads to novel conductance distribution functions and a
shortening of the conductance decay length.


title:
$L^p-L^q$ estimates on the solutions to $u_{tt}-u_{x_1x_1}=\triangle
  u_t$

abstract:
  This paper focuses the study on the $L^p-L^q$ estimates on the solutions to
an asymmetric wave equation with dissipation which arises in the study for the
magneto-hydrodynamics by using the method of Green function.


title:
On degeneration of surface in Fitting compactification of moduli of
  stable vector bundles

abstract:
  The new compactification of moduli scheme of Gieseker-stable vector bundles
with the given Hilbert polynomial on a smooth projective polarized surface
(S;H), over the field k = \bar k of zero characteristic, is constructed in
previous papers of the author. Families of locally free sheaves on the surface
S are completed by the locally free sheaves on the schemes which are certain
modifications of S. We obtain the class of modified surfaces to appear in the
construction. Keywords: moduli space, semistable coherent sheaves, blowup
algebra, algebraic surface.


title: Meson-meson interactions and Regge propagators

abstract:
  By a reformulation of the loop expansion in the Resonance-Spectrum-Expansion
amplitude for meson-meson scattering, in terms of s-channel exchange of
families of propagator modes, we obtain a formalism which allows for a wider
range of applications. The connection with the unitarized amplitudes employed
in some chiral theories is discussed. We also define an alternative for the
Regge spectra and indicate how this may be observed in experiment.


title:
Lifetime of the A(v'=0) state and Franck-Condon factor of the A-X(0-0)
  transition of CaF measured by the saturation of laser-induced fluorescence

abstract:
  We describe a method for determining the radiative decay properties of a
molecule by studying the saturation of laser-induced fluorescence and the
associated power broadening of spectral lines. The fluorescence saturates
because the molecules decay to states that are not resonant with the laser. The
amplitudes and widths of two hyperfine components of a spectral line are
measured over a range of laser intensities and the results compared to a model
of the laser-molecule interaction. Using this method we measure the lifetime of
the A(v'=0) state of CaF to be tau=19.2 \pm 0.7 ns, and the Franck-Condon
factor for the transition to the X(v=0) state to be Z=0.987 (+0.013 || -0.019).
In addition, our analysis provides a measure of the hyperfine interval in the
lowest-lying state of A(v'=0), Delta_e=4.8 \pm 1.1 MHz.


title:
Possible psi(5S), psi(4D), psi(6S) and psi(5D) signals in
  Lambda(c)-antiLambda(c)

abstract:
  It is shown that the Lambda(c+)-Lambda(c-) signal recently reported by the
Belle Collaboration (ARXIV:0807.4458) contains clear signs of the psi(5S) and
the psi(4D) c-cbar vector states, and also some indication for the masses and
widths of the psi(6S) and psi(5D). Moreover, it is argued that the threshold
behaviour of the Lambda(c+)-antiLambda(c-) cross sections suggests the presence
of the hitherto undetected psi(3D) state not far below the
Lambda(c+)-Lambda(c-) threshold.


title:
Wave dynamics of phantom scalar perturbation in the background of
  Schwarzschild black hole

abstract:
  Using Leaver's continue fraction and time domain method, we investigate the
wave dynamics of phantom scalar perturbation in the background of Schwarzschild
black hole. We find that the presence of the negative kinetic energy terms
modifies the standard results in quasinormal spectrums and late-time behaviors
of the scalar perturbations. The phantom scalar perturbation in the late-time
evolution will grow with an exponential rate.


title:
Measurement of unpolarized semi-inclusive pi+ electroproduction off the
  proton

abstract:
  Semi-inclusive pi+ electroproduction on protons has been measured with the
CLAS detector at Jefferson Lab. The measurement was performed on a
liquid-hydrogen target using a 5.75 GeV electron beam. The complete five-fold
differential cross sections were measured over a wide kinematic range including
the complete range of azimuthal angles between hadronic and leptonic planes,
phi, enabling us to separate the phi-dependent terms. Our measurements of
phi-independent term of the cross section at low Bjorken x were found to be in
fairly good agreement with pQCD calculations. Indeed, the conventional current
fragmentation calculation can account for almost all of the observed cross
section, even at small pi+ momentum. The measured center-of-momentum spectra
are in qualitative agreement with high energy data, which suggests a surprising
numerical similarity between the spectator diquark fragmentation in the present
reaction and the anti-quark fragmentation measured in e+e- collisions. We have
observed that the two phi-dependent terms of the cross section are small.
Within our precision the cos(2phi) term is compatible with zero, except for
low-z region, and the measured cos(phi) term is much smaller in magnitude than
the sum of the Cahn and Berger effects.


title: Assisted tunneling of a wave packet between square barriers

abstract:
  The assisted tunneling of a wave packet between square one dimensional
barriers is treated analytically. The tunneling rate is calculated exactly for
a potential mimicking a constant electric field with arbitrary time dependence.
The pole spectrum of the barriers determines the decay time. The tunneling
probability is enhanced by the perturbation. The results are exemplified for a
simplified model of nuclear $\ds \alpha$ decay.


title: Coronal Alfven speeds in an isothermal atmosphere I. Global properties

abstract:
  Estimating Alfven speeds is of interest in modelling the solar corona,
studying the coronal heating problem and understanding the initiation and
propagation of coronal mass ejections (CMEs). We assume here that the corona is
in a magnetohydrostatic equilibrium and that, because of the low plasma beta,
one may decouple the magnetic forces from pressure and gravity. The magnetic
field is then described by a force-free field for which we perform a
statistical study of the magnetic field strength with height for four different
active regions. The plasma along each field line is assumed to be in a
hydrostatic equilibrium. As a first approximation, the coronal plasma is
assumed to be isothermal with a constant or varying gravity with height. We
study a bipolar magnetic field with a ring distribution of currents, and apply
this method to four active regions associated with different eruptive events.
By studying the global properties of the magnetic field strength above active
regions, we conclude that (i) most of the magnetic flux is localized within 50
Mm of the photosphere, (ii) most of the energy is stored in the corona below
150 Mm, (iii) most of the magnetic field strength decays with height for a
nonlinear force-free field slower than for a potential field. The Alfven speed
values in an isothermal atmosphere can vary by two orders of magnitude (up to
100000 km/s). The global properties of the Alfven speed are sensitive to the
nature of the magnetic configuration. For an active region with highly twisted
flux tubes, the Alfven speed is significantly increased at the typical height
of the twisted flux bundles; in flaring regions, the average Alfven speeds are
above 5000 km/s and depart strongly from potential field values.


title: New half supersymmetric solutions of the heterotic string

abstract:
  We describe all supersymmetric solutions of the heterotic string which
preserve 8 supersymmetries and show that are distinguished by the holonomy,
${\rm hol}(\hat\nabla)$, of the connection, $\hat\nabla$, with skew-symmetric
torsion. The ${\rm hol}(\hat\nabla) \subseteq SU(2)$ solutions are principal
bundles over a 4-dimensional hyper-K\"ahler manifold equipped with a
anti-self-dual connection and fibre group $G$ which has Lie algebra,
${\mathfrak Lie} (G)=\bR^{5,1}$, $\mathfrak{sl}(2,\bR)\oplus \mathfrak{su}(2)$
or $\mathfrak{cw}_6$. Some of the solutions have the interpretation as 5-branes
wrapped on $G$ with transverse space any hyper-K\"ahler 4-dimensional manifold.
We construct new solutions for ${\mathfrak Lie} (G)=\mathfrak{sl}(2,\bR)\oplus
\mathfrak{su}(2)$ and show that are characterized by 3 integers and have
continuous moduli. There is also a smooth family in this class with one
asymptotic region and the dilaton is bounded everywhere on the spacetime. We
also demonstrate that the worldvolume theory of the backgrounds with holonomy
SU(2) can be understood in terms of gauged WZW models for which the gauge
fields are composite. The ${\rm hol}(\hat\nabla) \subseteq\bR^8$ solutions are
superpositions of fundamental strings and pp-waves in flat space, which may
also include a null rotation. The ${\rm hol}(\hat\nabla)=\{1\}$ heterotic
string backgrounds which preserve 8 supersymmetries are Lorentzian group
manifolds.


title: Constraints on "rare" dyon decays

abstract:
  We obtain the complete set of constraints on the moduli of N=4 superstring
compactifications that permit "rare" marginal decays of 1/4-BPS dyons to take
place. The constraints are analysed in some special cases. The analysis extends
in a straightforward way to multi-particle decays. We discuss the possible
relation between general multi-particle decays and multi-centred black holes.


title: Combinatorial differential geometry and ideal Bianchi-Ricci identities

abstract:
  We apply the graph complex method to vector fields depending naturally on a
set of vector fields and a linear symmetric connection. We characterize all
possible systems of generators for such vector-field valued operators including
the classical ones given by normal tensors and covariant derivatives. We also
describe the size of the space of such operators and prove the existence of an
`ideal' basis consisting of operators with given leading terms which satisfy
the (generalized) Bianchi-Ricci identities without the correction terms.


title:
Do submillimeter galaxies really trace the most massive dark matter
  halos? Discovery of a high-z cluster in a highly active phase of evolution

abstract:
  We present detailed observations of a z~1.99 cluster of submillimeter
galaxies (SMGs), discovered as the strongest redshift spike in our entire
survey of ~100 SMGs across 800 square arcmin. It is the largest blank-field SMG
concentration currently known and has <0.01% chance of being drawn from the
underlying selection function for SMGs. We have compared UV observations of
galaxies at this redshift, where we find a much less dramatic overdensity,
having an 11% chance of being drawn from its selection function. We use this
z~1.99 overdensity to compare the biasing of UV- and submm-selected galaxies,
and test whether SMGs could reside in less overdense environments, with their
apparent clustering signal being dominated by highly active merger periods in
modest mass structures. This impressively active formation phase in a low mass
cluster is not something seen in simulations, although we propose a toy model
using merger bias which could account for the bias seen in the SMGs. While
enhanced buildup of stellar mass appears characteristic of other high-z galaxy
clusters, neither the UV- nor submm-galaxies in this structure exhibit larger
stellar masses than their field galaxy counterparts (although the excess of
SMGs in the structure represents a larger volume-averaged stellar mass than the
field). Our findings have strong implications for future surveys for high-z
galaxies at long wavelengths such as SCUBA2 and Herschel. We suggest that since
these surveys will select galaxies during their episodes of peak starbursts,
they could probe a much wider range of environments than just the progenitors
of rich clusters, revealing more completely the key events and stages in galaxy
formation and assembly.


title: Discrete BF theory

abstract:
  In this work we discuss the simplicial program for topological field theories
for the case of non-abelian BF theory. Discrete BF theory with
finite-dimensional space of fields is constructed for a triangulated manifold
(or for a manifold equipped with cubical cell decomposition), that is in a
sense equivalent to the topological BF theory on manifold. This discrete
version allows one to calculate interesting quantities from the BF theory, like
the effective action on cohomology, in terms of finite-dimensional integrals
instead of functional integrals, as demonstrated in a series of explicit
examples. We also discuss the interpretation of discrete BF action as the
generating function for $qL_\infty$ structure (certain "one-loop version" of
ordinary $L_\infty$ algebra) on the cell cochains of triangulation, related to
the de Rham algebra of the underlying manifold by homotopy transfer procedure.
This work is a refinement of older text hep-th/0610326.


title:
Extended scaling for ferromagnetic Ising models with zero-temperature
  transitions

abstract:
  We study the second-moment correlation length and the reduced susceptibility
of two ferromagnetic Ising models with zero-temperature ordering. By
introducing a scaling variable motivated by high-temperature series expansions,
we are able to scale data for the one-dimensional Ising ferromagnet rigorously
over the entire temperature range. Analogous scaling expressions are then
applied to the two-dimensional fully frustrated Villain model where excellent
finite-size scaling over the entire temperature range is achieved. Thus we
broaden the applicability of the extended scaling method to Ising systems
having a zero-temperature critical point.


title: Effect of high-k environment on charge carrier mobility in graphene

abstract:
  It is widely assumed that the dominant source of scattering in graphene is
charged impurities in a substrate. We have tested this conjecture by studying
graphene placed on various substrates and in high-k media. Unexpectedly, we
have found no significant changes in carrier mobility either for different
substrates or by using glycerol, ethanol and water as a top dielectric layer.
This suggests that Coulomb impurities are not the scattering mechanism that
limits the mean free path currently attainable for graphene on a substrate.


title: Betti numbers of transversal monomial ideals

abstract:
  In this paper, by a modification of a previously constructed minimal free
resolution for a transversal monomial ideal, the Betti numbers of this ideal is
explicitly computed. For convenient characteristics of the ground field, up to
a change of coordinates, the ideal of $t$-minors of a generic pluri-circulant
matrix is a transversal monomial ideal . Using a Gr\"obner basis for this
ideal, it is shown that the initial ideal of a generic pluri-circulant matrix
is a stable monomial ideal when the matrix has two square blocks. By means of
the Eliahou-Kervair resolution, the Betti numbers of this initial ideal is
computed and it is proved that, for some significant values of $t$, this ideal
has the same Betti numbers as the corresponding transversal monomial ideal. The
ideals treated in this paper, naturally arise in the study of generic
singularities of algebraic varieties.


title:
Global Well-posedness of the 1D Dirac-Klein-Gordon system in Sobolev
  spaces of negative index

abstract:
  We prove that the Cauchy problem for the Dirac-Klein-Gordon system of
equations in 1D is globally well-posed in a range of Sobolev spaces of negative
index for the Dirac spinor and positive index for the scalar field. The main
ingredient in the proof is the theory of almost conservation law and I-method
introduced by Colliander, Keel, Staffilani, Takaoka and Tao. Our proof also
relies on the null structure in the system, and bilinear spacetime estimates of
Klainerman-Machedon type.


title:
Turbulent Flow in Pipes and Channels as Cross-Stream "Inverse Cascades"
  of Vorticity

abstract:
  A commonplace view of pressure-driven turbulence in pipes and channels is as
"cascades" of streamwise momentum toward the viscous layer at the wall. We
present in this paper an alternative picture of these flows as "inverse
cascades" of spanwise vorticity, in the cross-stream direction but away from
the viscous sublayer. We show that there is a constant spatial flux of spanwise
vorticity, due to vorticity conservation, and that this flux is necessary to
produce pressure-drop and energy dissipation. The vorticity transport is shown
to be dominated by viscous diffusion at distances closer to the wall than the
peak Reynolds stress, well into the classical log-layer. The Perry-Chong model
based on "representative" hairpin/horsehoe vortices predicts a single sign of
the turbulent vorticity flux over the whole log-layer, whereas the actual flux
must change sign at the location of the Reynolds-stress maximum. Sign-reversal
may be achieved by assuming a slow power-law decay of the Townsend "eddy
intensity function" for wall-normal distances greater than the hairpin
length-scale. The vortex-cascade picture presented here has a close analogue in
the theory of quantum superfluids and superconductors, the "phase slippage" of
quantized vortex lines. Most of our results should therefore apply as well to
superfluid turbulence in pipes and channels. We also discuss issues about
drag-reduction from this perspective.


title: Information geometry in vapour-liquid equilibrium

abstract:
  Using the square-root map p-->\sqrt{p} a probability density function p can
be represented as a point of the unit sphere S in the Hilbert space of
square-integrable functions. If the density function depends smoothly on a set
of parameters, the image of the map forms a Riemannian submanifold M in S. The
metric on M induced by the ambient spherical geometry of S is the Fisher
information matrix. Statistical properties of the system modelled by a
parametric density function p can then be expressed in terms of information
geometry. An elementary introduction to information geometry is presented,
followed by a precise geometric characterisation of the family of Gaussian
density functions. When the parametric density function describes the
equilibrium state of a physical system, certain physical characteristics can be
identified with geometric features of the associated information manifold M.
Applying this idea, the properties of vapour-liquid phase transitions are
elucidated in geometrical terms. For an ideal gas, phase transitions are absent
and the geometry of M is flat. In this case, the solutions to the geodesic
equations yield the adiabatic equations of state. For a van der Waals gas, the
associated geometry of M is highly nontrivial. The scalar curvature of M
diverges along the spinodal boundary which envelopes the unphysical region in
the phase diagram. The curvature is thus closely related to the stability of
the system.