title: On the maximal superalgebras of supersymmetric backgrounds

abstract:
  In this note we give a precise definition of the notion of a maximal
superalgebra of certain types of supersymmetric supergravity backgrounds,
including the Freund-Rubin backgrounds, and propose a geometric construction
extending the well-known construction of its Killing superalgebra. We determine
the structure of maximal Lie superalgebras and show that there is a finite
number of isomorphism classes, all related via contractions from an
orthosymplectic Lie superalgebra. We use the structure theory to show that
maximally supersymmetric waves do not possess such a maximal superalgebra, but
that the maximally supersymmetric Freund-Rubin backgrounds do. We perform the
explicit geometric construction of the maximal superalgebra of AdS_4 x S^7 and
find that is isomorphic to osp(1|32). We propose an algebraic construction of
the maximal superalgebra of any background asymptotic to AdS_4 x S^7 and we
test this proposal by computing the maximal superalgebra of the M2-brane in its
two maximally supersymmetric limits, finding agreement.


title:
Ray-tracing through the Millennium Simulation: Born corrections and
  lens-lens coupling in cosmic shear and galaxy-galaxy lensing

abstract:
  (abridged) We study the accuracy of various approximations to cosmic shear
and weak galaxy-galaxy lensing and investigate effects of Born corrections and
lens-lens coupling. We use ray-tracing through the Millennium Simulation to
calculate various cosmic-shear and galaxy-galaxy-lensing statistics. We compare
the results from ray-tracing to semi-analytic predictions. We find: (i) The
linear approximation provides an excellent fit to cosmic-shear power spectra as
long as the actual matter power spectrum is used as input. Common fitting
formulae, however, strongly underestimate the cosmic-shear power spectra. Halo
models provide a better fit to cosmic shear-power spectra, but there are still
noticeable deviations. (ii) Cosmic-shear B-modes induced by Born corrections
and lens-lens coupling are at least three orders of magnitude smaller than
cosmic-shear E-modes. Semi-analytic extensions to the linear approximation
predict the right order of magnitude for the B-mode. Compared to the
ray-tracing results, however, the semi-analytic predictions may differ by a
factor two on small scales and also show a different scale dependence. (iii)
The linear approximation may under- or overestimate the galaxy-galaxy-lensing
shear signal by several percent due to the neglect of magnification bias, which
may lead to a correlation between the shear and the observed number density of
lenses. We conclude: (i) Current semi-analytic models need to be improved in
order to match the degree of statistical accuracy expected for future
weak-lensing surveys. (ii) Shear B-modes induced by corrections to the linear
approximation are not important for future cosmic-shear surveys. (iii)
Magnification bias can be important for galaxy-galaxy-lensing surveys.


title: Disorder and critical phenomena

abstract:
  In the present paper we are discussing the influence of the fractal
distribution of defects on the critical behavior of the system. We consider a
case when the equation of motion for the order parameter contains influences of
defects of random field and random temperature types at the same time and we
show that it can lead to a change of distribution function from Gibbs
distribution to Tsallis distribution or more general statistics of q-type. We
are able to extend the Landau-Khalatnikov equation for the order parameter and
represent it in the form of a differential equation of the fractional order. We
deduce and we solve the corresponding renormalization group equation with the
nonlinear dispersion law and we calculate the critical indices of the system.


title: Coulomb Correlations and the Wigner-Mott Transition

abstract:
  Strong correlation effects, such as a dramatic increase in the effective mass
of the carriers of electricity, recently observed in the low density electron
gas have provided spectacular support for the existence of a sharp
metal-insulator transitions in dilute two dimensional electron gases. Here we
show that strong correlations, normally expected only for narrow integer filled
bands, can be effectively enhanced even far away from integer filling, due to
incipient charge ordering driven by non-local Coulomb interactions. This
general mechanism is illustrated by solving an extended Hubbard model using
dynamical mean-field theory. Our findings account for the key aspects of the
experimental phase diagram, and reconcile the early view points of Wigner and
Mott. The interplay of short range charge order and local correlations should
result in a three peak structure in the spectral function of the electrons
which should be observable in tunneling and optical spectroscopy.


title:
Role of Post-Selection in Two-Photon Interferometer Tests of Bell's
  Inequality

abstract:
  Experimental tests of Bell's inequality based on two-photon interferometry
consider only those coincidence events in which both photons arrive at the
detectors at the same time. In a recent paper, Cabello et al. [Phys. Rev. Lett.
102, 040401 (2009)] proposed a local model that is consistent with some aspects
of these experiments. It is shown here that the model proposed by Cabello et
al. is local but not realistic, and the role of post-selection in experiments
of this kind is discussed.


title: Robust strategies for lossy quantum interferometry

abstract:
  We give a simple multiround strategy that permits to beat the shot noise
limit when performing interferometric measurements even in the presence of
loss. In terms of the average photon number employed, our procedure can achieve
twice the sensitivity of conventional interferometric ones in the noiseless
case. In addition, it is more precise than the (recently proposed) optimal
two-mode strategy even in the presence of loss.


title: Dark Energy: A Missing Physical Ingredient

abstract:
  Recent observation of supernovae type Ia show clearly that there is a large
scale repulsive force in the Universe. Neither of the four known fundamental
interactions can account for this repulsive force. Gravity is known to be the
interaction responsible for the large scale structure and evolution of the
Universe. The problem with gravity is that it gives rise to a force which is
attractive only. Gravity theories, including General Relativity, deals with
gravity as an attractive force. Although this is consistent with our experience
in the solar system and other similar astrophysical systems, gravity theories
fail to account for SN type Ia observation. So, we are in a real problem
concerning the interpretation of these observation. This problem is only ten
years old. In order to go out of this problematic situation, scientists have
suggested the existence of a type of energy in the Universe that is responsible
for the above mentioned repulsive force. They have given this type of energy
the exotic term {\it "Dark Energy"}. Although this type of energy forms more
than two thirds of the energetic contents of our Universe, its reasonable
nature is missing in all gravity theories.
  The aim of the present work is to review the present status of the problem of
dark energy. Also, to suggest a new geometric solution for this problem.


title: VV Pup in a low state: secondary-star irradiation or stellar activity?

abstract:
  Aims. Emission lines in polars show complex profiles with multiple components
that are typically ascribed to the accretion stream, threading region,
accretion spot, and the irradiated secondary-star. In low-state polars the
fractional contribution by the accretion stream, and the accretion spot is
greatly reduced offering an opportunity to study the effect of the
secondary-star irradiation or stellar activity. We observed VV Pup during an
exceptional low-state to study and constrain the properties of the line-forming
regions and to search for evidence of chromospheric activity and/or
irradiation. Methods. We obtained phase-resolved optical spectra at the ESO
VLT+FORS1 with the aim of analyzing the emission line profile and radial
velocity as a function of the orbital period. We also tailored irradiated
secondary-star models to compare the predicted and the observed emission lines
and to establish the nature of the line-forming regions. Results. Our
observations and data analysis, when combined with models of the irradiated
secondary-star, show that, while the weak low ionization metal lines (FeI and
MgI) may be consistent with irradiation processes, the dominant Balmer H
emission lines, as well as NaI and HeI, cannot be reproduced by the irradiated
secondary-star models. We favor the secondary-star chromospheric activity as
the main forming region and cause of the observed H, NaI, and He emission
lines, though a threading region very close to the L1 point cannot be excluded.


title: The formation of brown dwarfs and low-mass stars by disc fragmentation

abstract:
  We suggest that a high proportion of brown dwarfs are formed by gravitational
fragmentation of massive, extended discs around Sun-like stars. We argue that
such discs should arise frequently, but should be observed infrequently,
precisely because they fragment rapidly. By performing an ensemble of
radiation-hydrodynamic simulations, we show that such discs typically fragment
within a few thousand years to produce mainly brown dwarfs (including
planetary-mass brown dwarfs) and low-mass hydrogen-burning stars. Subsequently
most of the brown dwarfs are ejected by mutual interactions. We analyse the
properties of these objects that form by disc fragmentation, and compare them
with observations.


title:
On the particle production threshold for ultra-relativistic accelerated
  protons

abstract:
  Non-electromagnetic emission from cosmic ray particles accelerated in extreme
environments has been studied using different variations of semi-classical
formalisms. As the energy loss mechanisms of such particles is of great
interest, one must improve in some sense the previously intuitive description
of classical sources in the presence of fields. In this brief note we evaluate
the role played by the classical and dimensional proper acceleration of a
particle in radiation processes. One intends to show that the introduction of
the acceleration as a measure parameter gives an adequate scale for considering
the processes of massive particle emission. If the acceleration threshold is
not attained one is considering a regime where the processes of massive
particle production are suppressed. The analysis is performed in a
semiclassical formalism once applied in different contexts and already checked
for consistency in a serie of papers. As a further application of the results
we evaluate the possibility of a non negligible meson production by protons
accelerated in the framework of polar cap models operating in electromagnetic
fields of pulsars. It is shown that inside a systems endowed with magnetic
fields B\geq 10^{12} G the meson emission by protons must not be disregarded.


title:
Equilibrium edge spin currents in two-dimensional electron systems with
  spin-orbit interaction

abstract:
  We find a specific mechanism of background spin currents in two-dimensional
electron systems with spatially nonuniform spin-orbit interaction (SOI) at
thermodynamic equilibrium, in particular, in the systems consisting of regions
with and without SOI. The spin density flows tangentially to the boundary in
the normal and SOI regions within a layer of the width determined by the SOI
strength. The density of these edge currents significantly exceeds the bulk
spin current density. The spin current is polarized normally to the boundary.
The spatial distribution of equilibrium spin currents is investigated in detail
in the case of a step-like variation of the SOI strength and potential at the
interface.


title:
Universal ratios of critical amplitudes in the Potts model universality
  class

abstract:
  Monte Carlo (MC) simulations and series expansions (SE) data for the energy,
specific heat, magnetization, and susceptibility of the three-state and
four-state Potts model and Baxter-Wu model on the square lattice are analyzed
in the vicinity of the critical point in order to estimate universal
combinations of critical amplitudes. We also form effective ratios of the
observables close to the critical point and analyze how they approach the
universal critical-amplitude ratios. In particular, using the duality relation,
we show analytically that for the Potts model with a number of states $q\le 4$,
the effective ratio of the energy critical amplitudes always approaches unity
linearly with respect to the reduced temperature. This fact leads to the
prediction of relations among the amplitudes of correction-to-scaling terms of
the specific heat in the low- and high-temperature phases. It is a common
belief that the four-state Potts and the Baxter-Wu model belong to the same
universality class. At the same time, the critical behavior of the four-state
Potts model is modified by logarithmic corrections while that of the Baxter-Wu
model is not. Numerical analysis shows that critical amplitude ratios are very
close for both models and, therefore, gives support to the hypothesis that the
critical behavior of both systems is described by the same renormalization
group fixed point.


title: Hypercompact Stellar Systems Around Recoiling Supermassive Black Holes

abstract:
  A supermassive black hole ejected from the center of a galaxy by
gravitational wave recoil carries a retinue of bound stars - a "hypercompact
stellar system" (HCSS). The numbers and properties of HCSSs contain information
about the merger histories of galaxies, the late evolution of binary black
holes, and the distribution of gravitational-wave kicks. We relate the
structural properties of HCSSs to the properties of their host galaxies, in two
regimes: collisional, i.e. short nuclear relaxation times; and collisionless,
i.e. long nuclear relaxtion times. HCSSs are expected to be similar in size and
luminosity to globular clustersbut in extreme cases their stellar mass can
approach that of UCDs. However they differ from all other classes of compact
stellar system in having very high internal velocities. We show that the kick
velocity is encoded in the velocity dispersion of the bound stars. Given a
large enough sample of HCSSs, the distribution of gravitational-wave kicks can
therefore be empirically determined. We combine a hierarchical merger algorithm
with stellar population models to compute the rate of production of HCSSs over
time and the probability of observing HCSSs in the local universe as a function
of their apparent magnitude, color, size and velocity dispersion, under two
assumptions about the star formation history prior to the kick. We predict that
roughly 100 should be detectable within 2 Mpc of the center of the Virgo
cluster and that many of these should be bright enough that their high internal
velocity dispersions could be measured with reasonable exposure times.


title:
High-quality quantum point contact in two-dimensional GaAs (311)A hole
  system

abstract:
  We studied ballistic transport across a quantum point contact (QPC) defined
in a high-quality, GaAs (311)A two-dimensional (2D) hole system using shallow
etching and top-gating. The QPC conductance exhibits up to 11 quantized
plateaus. The ballistic one-dimensional subbands are tuned by changing the
lateral confinement and the Fermi energy of the holes in the QPC. We
demonstrate that the positions of the plateaus (in gate-voltage), the
source-drain data, and the negative magneto-resistance data can be understood
in a simple model that takes into account the variation, with gate bias, of the
hole density and the width of the QPC conducting channel.


title:
A multi-wavelength study of a double intermediate-mass protostar - from
  large-scale structure to collimated jets

abstract:
  (abridged) We study a previously discovered protostellar source that is
deeply embedded and drives an energetic molecular outflow. The source, UYSO1,
is located close to IRAS 07029-1215 at a distance of ~1 kpc. The
multi-wavelength observations resulted in the detection of a double
intermediate-mass protostar at the location of UYSO1. In addition to the
associated molecular outflow, with a projected size of 0.25 pc, two
intersecting near-infrared jets with projected sizes of 0.4 pc and 0.2 pc were
found. However, no infrared counterparts to the driving sources could be
detected in sensitive near- to far-infrared observations. In interferometric
millimeter observations, UYSO1 was resolved into two continuum sources with
high column densities and gas masses of 3.5 Mo and 1.2 Mo, with a linear
separation of 4200 AU. We report the discovery of a H2O maser toward one of the
two sources. The total luminosity is roughly estimated to be ~50 Lo, shared by
the two components, one of which is driving the molecular outflow that has a
dynamical timescale of less than a few thousand years. The jets of the two
individual components are not aligned. Submillimeter observations show that the
region lacks typical hot-core chemistry. We thus find two protostellar objects,
whose associated circumstellar and parent core masses are high enough to
suggest that they may evolve into intermediate-mass stars. This is corroborated
by their association with a very massive and energetic CO outflow, suggesting
high protostellar accretion rates. The short dynamical timescale of the
outflow, the pristine chemical composition of the cloud core and absence of hot
core tracers, the absence of detectable radio continuum emission, and the very
low protostellar luminosity argue for an extremely early evolutionary stage.


title: Universal properties of Wilson loop operators in large N QCD

abstract:
  Eigenvalues of a Wilson loop operator are gauge invariant and their
distribution undergoes a transition at infinite N as the size of the loop is
changed. We study this transition using the average characteristic polynomial
associated with the Wilson loop operator. We derive the scaling function in a
certain double scaling limit for two dimensional QCD and hypothesize that the
transition in three and four dimensional QCD are in the same universality
class. Numerical evidence for this hypothesisis provided in three dimensions


title: Large N transition in the 2D SU(N)xSU(N) nonlinear sigma model

abstract:
  We consider the characteristic polynomial associated with the smoothed two
point function in two dimensional large N principal chiral model. We
numerically show that it undergoes a transition at a critical distance of the
order of the correlation length. The transition is in the same universality
class as two dimensional large N QCD.


title:
Cooling of Dense Gas by H2O Line Emission and an Assessment of its
  Effects in Chondrule-Forming Shocks

abstract:
  We consider gas at densities appropriate to protoplanetary disks and
calculate its ability to cool due to line radiation emitted by H2O molecules
within the gas. Our work follows that of Neufeld & Kaufman (1993; ApJ, 418,
263), expanding on their work in several key aspects, including use of a much
expanded line database, an improved escape probability formulism, and the
inclusion of dust grains, which can absorb line photons. Although the escape
probabilities formally depend on a complicated combination of optical depth in
the lines and in the dust grains, we show that the cooling rate including dust
is well approximated by the dust-free cooling rate multiplied by a simple
function of the dust optical depth. We apply the resultant cooling rate of a
dust-gas mixture to the case of a solar nebula shock pertinent to the formation
of chondrules, millimeter-sized melt droplets found in meteorites. Our aim is
to assess whether line cooling can be neglected in chondrule-forming shocks or
if it must be included. We find that for typical parameters, H2O line cooling
shuts off a few minutes past the shock front; line photons that might otherwise
escape the shocked region and cool the gas will be absorbed by dust grains.
During the first minute or so past the shock, however, line photons will cool
the gas at rates ~ 10,000 K/hr, dropping the temperature of the gas (and most
likely the chondrules within the gas) by several hundred K. Inclusion of H2O
line cooling therefore must be included in models of chondrule formation by
nebular shocks.


title:
Global well-posedness of the short-pulse and sine-Gordon equations in
  energy space

abstract:
  We prove global well-posedness of the short-pulse equation with small initial
data in Sobolev space $H^2$. Our analysis relies on local well-posedness
results of Sch\"afer & Wayne, the correspondence of the short-pulse equation to
the sine-Gordon equation in characteristic coordinates, and a number of
conserved quantities of the short-pulse equation. We also prove local and
global well-posedness of the sine-Gordon equation in an appropriate function
space.


title: On the low energy end of the QCD spectrum

abstract:
  The energy gap of QCD is now understood very well. There is no doubt that the
expansion in powers of the two lightest quark masses does represent a very
useful tool for the analysis of the low energy structure. Concerning the
expansion in powers of m_s, however, the current situation leaves much to be
desired. While some of the lattice results indicate, for instance, that the
violations of the Okubo-Iizuka-Zweig rule in the quark condensate and in the
decay constants are rather modest, others point in the opposite direction. I am
confident that the dust will settle soon, so that the effective coupling
constants that govern the dependence of the various quantities of physical
interest on m_s can be determined, to next-to-next-to-leading order of the
chiral expansion.
  The range of validity of ChPT can be extended by means of dispersive methods.
The properties of the physical states occurring in the spectrum of QCD below
KKbar threshold can reliably be investigated on this basis. In particular, as
shown only rather recently, general principles of quantum field theory lead to
an exact formula that expresses the mass and width of resonances in terms of
observable quantities. The formula removes the ambiguities inherent in the
analytic continuation from the real axis into the complex plane, which plagued
previous determinations of the pole positions of broad resonances.


title:
Spatially Resolved Spectroscopy of Sub-AU-Sized Regions of T Tauri and
  Herbig Ae/Be Disks

abstract:
  We present spatially resolved near-IR spectroscopic observations of 15 young
stars. Using a grism spectrometer behind the Keck Interferometer, we obtained
an angular resolution of a few milli-arcseconds and a spectral resolution of
230, enabling probes of both gas and dust in the inner disks surrounding the
target stars. We find that the angular size of the near-IR emission typically
increases with wavelength, indicating hot, presumably gaseous material within
the dust sublimation radius. Our data also clearly indicate Brackett-gamma
emission arising from hot hydrogen gas, and suggest the presence of water vapor
and carbon monoxide gas in the inner disks of several objects. This gaseous
emission is more compact than the dust continuum emission in all cases. We
construct simple physical models of the inner disk and fit them to our data to
constrain the spatial distribution and temperature of dust and gas emission
components.


title:
UHECR observations and lensing in the magnetic field of the Virgo
  cluster

abstract:
  We discuss how lensing by magnetic fields in galaxy clusters affects
ultrahigh energy cosmic ray (UHECR) observations. As specific example, we use
Virgo together with the cluster magnetic fields obtained earlier in a
constrained simulation of structure formation including MHD processes. We find
that, if M87 is the single source of UHECRs from Virgo, the emitted flux is
strongly anisotropic in the most interesting energy range, (50-100)EeV, and
differs from the average value by a factor five or more for a significant
fraction of observers. Since magnetic lensing is energy dependent, the external
energy spectrum as seen by different observers varies strongly too. These
anisotropies are averaged out in the case that all active galactic nuclei in
Virgo emit UHECRs. In both cases, the anisotropies of the emitted UHECR flux
may introduce an important bias in the interpretation of UHECR data like, e.g.,
the determination of the source density n_s and the source energy spectrum of
UHECRs.


title:
A joint model for the emission and absorption properties of damped Lyman
  alpha absorption systems

abstract:
  The recently discovered population of ultra-faint extended line emitters can
account for the majority of the incidence rate of Damped Lyman Alpha systems
(DLAs) at z ~ 3 if the line emission is interpreted as Ly alpha. We show here
that a model similar to that proposed by Haehnelt, Steinmetz, & Rauch (2000),
which explains the incidence rate and kinematics of DLAs in the context of
$\Lambda$CDM models for structure formation, also reproduces the size
distribution of the new population of faint Ly alpha emitters for plausible
parameters. This lends further support to identification of the emitters with
the hitherto elusive population of DLA host galaxies. The observed incidence
rate of DLAs together with the observed space density and size distribution of
the emitters suggest a duty cycle of ~ 0.2 - 0.4 for the Ly alpha emission from
DLA host galaxies. We further show that Ly alpha cooling is expected to
contribute little to the Ly alpha emission for the majority of emitters. This
leaves centrally concentrated star formation at a rate of a few tenths
M_sun/yr, surrounded by extended Ly alpha halos with radii up to 30-50 kpc, as
the most plausible explanation for the origin of the emission. Both the
luminosity function of Ly alpha emission and the velocity width distribution of
low ionization absorption require that galaxies inside Dark Matter (DM) halos
with virial velocities < 50 - 70 km/s contribute little to the incidence rate
of DLAs at z ~ 3, suggesting that energy and momentum input due to star
formation efficiently removes gas from these halos. Galaxies with DM halos with
virial velocities of 100 - 150 km/s appear to account for the majority of DLA
host galaxies. DLA host galaxies at z ~ 3 should thus become the building
blocks of typical present-day galaxies.


title:
A New Method for Estimating Dark Matter Halo Masses using Globular
  Cluster Systems

abstract:
  All galaxies are thought to reside within large halos of dark matter, whose
properties can only be determined from indirect observations. The formation and
assembly of galaxies is determined from the interplay between these dark matter
halos and the baryonic matter they host. Although statistical relations can be
used to approximate how massive a galaxy's halo is, very few individual
galaxies have direct measurements of their halo masses. We present a method to
directly estimate the total mass of a galaxy's dark halo using its system of
globular clusters. The link between globular cluster systems and halo masses is
independent of a galaxy's type and environment, in contrast to the relationship
between galaxy halo and stellar masses. This trend is expected in models where
globular clusters form in early, rare density peaks in the cold dark matter
density field and the epoch of reionisation was roughly coeval throughout the
Universe. We illustrate the general utility of this relation by demonstrating
that a galaxy's supermassive black hole mass and global X-ray luminosity are
directly proportional to their host dark halo masses, as inferred from our new
method.


title:
The Chandra Deep Protocluster Survey: Evidence for an Enhancement in the
  AGN Activity in the SSA22 Protocluster at z = 3.09

abstract:
  We present results from a new ultra-deep 400 ks Chandra observation of the
SSA22 protocluster at z = 3.09. We have studied the X-ray properties of 234 z ~
3 Lyman break galaxies (LBGs; protocluster and field) and 158 z = 3.09 Ly-alpha
emitters (LAEs) in SSA22 to measure the influence of the high-density
protocluster environment on the accretion activity of supermassive black holes
(SMBHs) in these UV-selected star forming populations. We detect individually
X-ray emission from active galactic nuclei (AGNs) in six LBGs and five LAEs;
due to small overlap between the LBG and LAE source population, ten of these
sources are unique. At least six and potentially eight of these sources are
members of the protocluster. These sources have rest-frame 8-32 keV
luminosities in the range of L_8-32 keV = (3-50) X 10^{43} ergs/s and an
average observed-frame 2-8 keV to 0.5-2 keV band-ratio of ~0.8 (mean effective
photon index of Gamma_eff = 1.1), suggesting significant absorption columns of
N_H > 10^{22}-10^{24} cm^{-2}. We find that the fraction of LBGs and LAEs in
the z = 3.09 protocluster harboring an AGN with L_8-32 keV > 3 X 10^{43} ergs/s
is 9.5^{+12.7}_{-6.1}% and 5.1^{+6.8}_{-3.3}%, respectively. These AGN
fractions are somewhat larger (by a mean factor of 6.1^{+10.3}_{-3.6};
significant at the 95% confidence level) than z ~ 3 sources found in
lower-density "field" environments. Theoretical models imply that these results
may be due to the presence of more actively growing and/or massive SMBHs in
LBGs and LAEs within the protocluster compared to the field. Such a result is
expected in a scenario where enhanced merger activity in the protocluster
drives accelerated galaxy and SMBH growth at z > 2-3. (abridged)


title:
The Recent Star Formation Histories of M81 Group Dwarf Irregular
  Galaxies

abstract:
  We present observations and analysis of nine dwarf irregular galaxies (dIs)
in the M81 Group taken with the Advanced Camera for Surveys aboard the Hubble
Space Telescope. The nine galaxy sample (the Garland, M81 Dwarf A, DDO 53, Ho
IX, Ho I, DDO 165, NGC 2366, Ho II, and IC 2574) spans 6 magnitudes in
luminosity, a factor of 1000 in current star formation rate, and 0.5 dex in
metallicity. Here we use color-magnitude diagrams of resolved stellar
populations to study the star formation histories (SFHs) of these galaxies. We
divide the sample into faint and bright galaxies, with a dividing line of
M_${B}$ = -15, and then analyze the similarities and differences in the SFHs,
birthrate parameters, fraction of stars formed per time interval, and spatial
distribution of stellar components. Comparing these parameters as a function of
luminosity, we find only minor differences in SF characteristics. We extend our
comparison to select dIs in the Local Group (LG), and find only minor
differences in SF parameters. The fraction of stars formed per time interval
for an average M81 Group and LG dI is consistent with a constant SFH. However,
individual galaxies can show significant departures from a constant SFH. Thus,
we find this result underlines the importance of stochastic SF in dIs. We also
compare possible formation scenarios of the less luminous and candidate tidal
dwarfs in the M81 Group. The SFHs and the lack of an overdensity of associated
red stars suggest that the Garland and Ho IX are not dIs and are potentially
tidal dwarf galaxies. Interestingly, a noteworthy difference between the LG and
the M81 Group is the lack of tidal dwarf candidates in the LG.


title: Quantum Vortex Strings: A Review

abstract:
  The quantum worldsheet dynamics of vortex strings contains information about
the 4d non-Abelian gauge theory in which the string lives. Here I tell this
story. The string worldsheet theory is typically some variant of the CP^{N-1}
sigma-model, describing the orientation of the string in a U(N) gauge group.
Qualitative parallels between 2d sigma-models and 4d non-Abelian gauge theories
have been known since the 1970s. The vortex string provides a quantitative link
between the two. In 4d theories with N=2 supersymmetry, the exact BPS spectrum
of the worldsheet coincides with the bulk spectrum in 4d. Moreover, by tuning
parameters, the CP^{N-1} sigma-model can be coaxed to flow to an interacting
conformal fixed point which is related to the 4d Argyres-Douglas fixed point.
For theories with N=1 supersymmetry, the worldsheet theory suffers dynamical
supersymmetry breaking and, more interestingly, supersymmetry restoration, in a
way which captures the physics of Seiberg's quantum deformed moduli space.


title: Random Sequential Adsorption of Objects of Decreasing Size

abstract:
  We consider the model of random sequential adsorption, with depositing
objects, as well as those already at the surface, decreasing in size according
to a specified time dependence, from a larger initial value to a finite value
in the large time limit. Numerical Monte Carlo simulations of two-dimensional
deposition of disks and one-dimensional deposition of segments are reported for
the density-density correlation function and gap-size distribution function,
respectively. Analytical considerations supplement numerical results in the
one-dimensional case. We investigate the correlation hole - the depletion of
correlation functions near contact and, for the present model, their vanishing
at contact - that opens up at finite times, as well as its closing and
reemergence of the logarithmic divergence of correlation properties at contact
in the large time limit.


title: Black Hole Berry Phase

abstract:
  Supersymmetric black holes are characterized by a large number of degenerate
ground states. We argue that these black holes, like other quantum mechanical
systems with such a degeneracy, are subject to a phenomenon which is called the
geometric or Berry's phase: under adiabatic variations of the background values
of the supergravity moduli, the quantum microstates of the black hole mix among
themselves. We present a simple example where this mixing is exactly
computable, that of small supersymmetric black holes in 5 dimensions. While in
practice it would be extremely difficult to measure Berry's phase for black
holes, it may be interesting to explore it further from a theoretical point of
view, as it provides us with a way to probe, and to some degree manipulate, the
quantum microstate of the black hole.


title: The Fibonacci scheme for fault-tolerant quantum computation

abstract:
  We rigorously analyze Knill's Fibonacci scheme for fault-tolerant quantum
computation, which is based on the recursive preparation of Bell states
protected by a concatenated error-detecting code. We prove lower bounds on the
threshold fault rate of .67\times 10^{-3} for adversarial local stochastic
noise, and 1.25\times 10^{-3} for independent depolarizing noise. In contrast
to other schemes with comparable proved accuracy thresholds, the Fibonacci
scheme has a significantly reduced overhead cost because it uses postselection
far more sparingly.


title: Gauge vs. Gravity mediation in models with anomalous U(1)'s

abstract:
  In an attempt to implement gauge mediation in string theory, we study string
effective supergravity models of supersymmetry breaking, containing anomalous
gauge factors. We discuss subtleties related to gauge invariance and the
stabilization of the Green-Schwarz moduli, which set non-trivial constraints on
the transmission of supersymmetry breaking to MSSM via gauge interactions.
Given those constraints, it is difficult to obtain the dominance of gauge
mediation over gravity mediation. Furthermore, generically the gauge
contributions to soft terms contain additional non-standard terms coming from
D-term contributions. Motivated by this, we study the phenomenology of recently
proposed hybrid models, where gravity and gauge mediations compete at the GUT
scale, and show that such a scenario can respect WMAP constraints and would be
easily testable at LHC.


title: Impurity states of electrons in quantum dots in external magnetic fields

abstract:
  The influence of isolated impurity atoms on the electron energy spectrum in a
parabolic quantum dot in quantizing magnetic field is studied. The impurity
potential is approximated by a Gaussian separable operator which allows one to
obtain the exact solution of the problem. We demonstrate that in the electron
energy spectrum there is a set of local levels which are split from the Landau
zone boundaries in the upward or downward direction depending on the impurity
type. We have calculated the local level positions, the wave functions of
electrons in bound states, and the residues of the electron scattering
amplitudes by impurity atoms at the poles.


title:
Design of an ultrahigh Quality factor silicon nitride photonic crystal
  nanocavity for coupling to diamond nanocrystals

abstract:
  A photonic crystal nanocavity with a Quality (Q) factor of 2.3 x 10^5, a mode
volume of 0.55($\lambda/n$)^3, and an operating wavelength of 637 nm is
designed in a silicon nitride (SiN_x) ridge waveguide with refractive index of
2.0. The effect on the cavity Q factor and mode volume of single diamond
nanocrystals of various sizes and locations embedded in the center and on top
of the nanocavity is simulated, demonstrating that Q > 2 x 10^5 is achievable
for realistic parameters. An analysis of the figures of merit for cavity
quantum electrodynamics reveals that strong coupling between an embedded
diamond nitrogen-vacancy center and the cavity mode is achievable for a range
of cavity dimensions.


title:
New Relativistic Particle-In-Cell Simulation Studies of Prompt and Early
  Afterglows from GRBs

abstract:
  Nonthermal radiation observed from astrophysical systems containing
relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic
nuclei (AGNs), and microquasars commonly exhibit power-law emission spectra.
Recent PIC simulations of relativistic electron-ion (or electron-positron) jets
injected into a stationary medium show that particle acceleration occurs within
the downstream jet. In collisionless, relativistic shocks, particle (electron,
positron, and ion) acceleration is due to plasma waves and their associated
instabilities (e.g., the Weibel (filamentation) instability) created in the
shock region. The simulations show that the Weibel instability is responsible
for generating and amplifying highly non-uniform, small-scale magnetic fields.
These fields contribute to the electron's transverse deflection behind the jet
head. The resulting "jitter" radiation from deflected electrons has different
properties compared to synchrotron radiation, which assumes a uniform magnetic
field. Jitter radiation may be important for understanding the complex time
evolution and/or spectra in gamma-ray bursts, relativistic jets in general, and
supernova remnants.


title: The Existence of Soliton Metrics for Nilpotent Lie Groups

abstract:
  We show that a left-invariant metric g on a nilpotent Lie group N is a
soliton metric if and only if a matrix U and vector v associated the manifold
(N,g) satisfy the matrix equation Uv = [1], where [1] is a vector with every
entry a one. We associate a generalized Cartan matrix to the matrix U and use
the theory of Kac-Moody algebras to analyze the solution spaces for such linear
systems. We use these methods to find infinitely many new examples of
nilmanifolds with soliton metrics. We give a sufficient condition for a sum of
soliton metric nilpotent Lie algebra structures to be soliton, and we use this
criterion to show that soliton metrics exist on every naturally graded filiform
metric Lie algebra.


title:
Weakly coupled $s = 1/2$ quantum spin singlets in
  Ba$_{3}$Cr$_{2}$O$_{8}$

abstract:
  Using single crystal inelastic neutron scattering with and without
application of an external magnetic field and powder neutron diffraction, we
have characterized magnetic interactions in Ba$_3$Cr$_2$O$_8$. Even without
field, we found that there exist three singlet-to-triplet excitation modes in
$(h,h,l)$ scattering plane. Our complete analysis shows that the three modes
are due to spatially anisotropic interdimer interactions that are induced by
local distortions of the tetrahedron of oxygens surrounding the Jahn-Teller
active Cr$^{5+} (3d^1)$. The strong intradimer coupling of $J_0 = 2.38(2)$ meV
and weak interdimer interactions ($|J_{\rm inter}| \leq 0.52(2)$ meV) makes
Ba$_3$Cr$_2$O$_8$ a good model system for weakly-coupled $s = 1/2$ quantum spin
dimers.


title:
The Generalized Bloch Conjecture for the quotient of certain Calabi-Yau
  varieties

abstract:
  In this paper, the generalized Bloch Conjecture on zero cycles for the
quotient of certain complete intersections with trivial canonical bundle is
proved to hold. As an application of Bloch-Srinivas method on the decomposition
of the diagonal, we compute the rational coefficient Lawson homology for
1-cycles and codimension two cycles for these quotient varieties. The
(Generalized) Hodge Conjecture is proved to hold for codimension two cycles
(and hence also for 2-cycles) on these quotient varieties.


title: Distortion of the perfect lattice structure in bilayer graphene

abstract:
  We consider the instability of bilayer graphene with respect to a distorted
configuration in the same spirit as the model introduced by Su, Schrieffer and
Heeger. By computing the total energy of a distorted bilayer, we conclude that
the ground state of the system favors a finite distortion. We explore how the
equilibrium configuration changes with carrier density and an applied potential
difference between the two layers.


title: Dark Matter Structures In The Deep Lens Survey

abstract:
  We present a regularized maximum likelihood weak lensing reconstruction of
the Deep Lens Survey F2 field (4 deg^2). High signal-to-noise ratio peaks in
our lensing significance map appear to be associated with possible projected
filamentary structures. The largest apparent structure extends for over a
degree in the field and has contributions from known optical clusters at three
redshifts (z ~ 0.3, 0.43, 0.5). Noise in weak lensing reconstructions is known
to potentially cause "false positives"; we use Monte Carlo techniques to
estimate the contamination in our sample, and find that 10-25% of the peaks are
expected to be false detections. For significant lensing peaks we estimate the
total signal-to-noise ratio of detection using a method that accounts for
pixel-to-pixel correlations in our reconstruction. We also report the detection
of a candidate relative underdensity in the F2 field with a total
signal-to-noise ratio of ~ 5.5.


title: Did Saturn's rings form during the Late Heavy Bombardment ?

abstract:
  The origin of Saturn\' s massive ring system is still unknown. Two popular
scenarios - the tidal splitting of passing comets and the collisional
destruction of a satellite - rely on a high cometary flux in the past. In the
present paper we attempt to quantify the cometary flux during the Late Heavy
Bombardment (LHB) to assess the likelihood of both scenarios. Our analysis
relies on the so-called Nice model of the origin of the LHB (Tsiganis et al.,
2005; Morbidelli et al., 2005; Gomes et al., 2005) and on the size distribution
of the primordial trans-Neptunian planetesimals constrained in Charnoz &
Morbidelli (2007). We find that the cometary flux on Saturn during the LHB was
so high that both scenarios for the formation of Saturn rings are viable in
principle. However, a more detailed study shows that the comet tidal disruption
scenario implies that all four giant planets should have comparable ring
systems whereas the destroyed satellite scenario would work only for Saturn,
and perhaps Jupiter. This is because in Saturn\'s system, the synchronous orbit
is interior to the Roche Limit, which is a necessary condition for maintaining
a satellite in the Roche zone up to the time of the LHB. We also discuss the
apparent elimination of silicates from the ring parent body implied by the
purity of the ice in Saturn \' s rings. The LHB has also strong implications
for the survival of the Saturnian satellites: all satellites smaller than Mimas
would have been destroyed during the LHB, whereas Enceladus would have had from
40% to 70% chance of survival depending on the disruption model. In conclusion,
these results suggest that the LHB is the sweet moment for the formation of a
massive ring system around Saturn.


title:
Neutron inelastic scattering and reactions in natural Pb as a background
  in neutrinoless double-beta-decay experiments

abstract:
  Inelastic neutron scattering and reactions on Pb isotopes can result in gamma
rays near the signature endpoint energy in a number of double-beta decay
isotopes. In particular, there are gamma-ray transitions in Pb-206,207,208 that
might produce energy deposits at the 76-Ge Q value in Ge detectors used for
double-beta decay searches. The levels that produce these gamma rays can be
excited by (n,n'gamma) or (n,xngamma) reactions, but the cross sections are
small and previously unmeasured. This work uses the pulsed neutron beam at the
Los Alamos Neutron Science Center to directly measure reactions of interest to
double-beta decay experiments. The cross section on natural Pb to produce the
2041-keV gamma ray from Pb-206 is measured to be 3.6 +/- 0.7 (stat.) +/- 0.3
(syst.) mb at ~9.6 MeV. The cross section on natural Pb to produce the 3062-keV
gamma ray from Pb-207 and Pb-208 is measured to be 3.9 +/- 0.8 (stat.) +/- 0.4
(syst.) mb at the same energy. We report cross sections or place upper limits
on the cross sections for exciting some other levels in Pb that have transition
energies corresponding to Q value in other double-beta decay isotopes.


title: On rack polynomials

abstract:
  We study rack polynomials and the link invariants they define. We show that
constant action racks are classified by their generalized rack polynomials and
show that $ns^at^a$-quandles are not classified by their generalized quandle
polynomials. We use subrack polynomials to define enhanced rack counting
invariants, generalizing the quandle polynomial invariants.


title:
Light Sterile Neutrino Effects at theta_13-Sensitive Reactor Neutrino
  Experiments

abstract:
  We study the impact of very light sterile neutrinos (Delta m^2_new around 1
to 10 times 10^(-2) eV^2, sin^2 2theta_new<10^(-1)) on upcoming theta_13-driven
reactor antineutrino experiments like Double-CHOOZ and Daya Bay. Oscillations
driven by these vales of Delta m^2_new affect data in the near and far
detectors differently and hence potentially modify the capability of these
experimental setups to constrain and measure sin^2 2theta_13. We find that the
hypothesis theta_new different from zero negatively impacts one's ability to
either place an upper bound on sin^2 2theta_13 in the advent of no oscillation
signal or measure sin^2 2theta_13 if a theta_13-driven signal is observed. The
impact of sterile neutrino effects, however, depends significantly on one's
ability to measure the recoil positron energy spectrum. If sin^2 2theta_new is
larger than 10^(-2), upcoming theta_13-driven reactor antineutrino experiments
should be able to measure sin^2 2theta_new and Delta m^2_new, along with sin^2
2theta_13, as long as one is sensitive to distortions in the recoil positron
energy spectrum in the near (and far) detectors.


title:
Application of a Self-Similar Pressure Profile to Sunyaev-Zel'dovich
  Effect Data from Galaxy Clusters

abstract:
  We investigate the utility of a new, self-similar pressure profile for
fitting Sunyaev-Zel'dovich (SZ) effect observations of galaxy clusters. Current
SZ imaging instruments - such as the Sunyaev-Zel'dovich Array (SZA) - are
capable of probing clusters over a large range in physical scale. A model is
therefore required that can accurately describe a cluster's pressure profile
over a broad range of radii, from the core of the cluster out to a significant
fraction of the virial radius. In the analysis presented here, we fit a radial
pressure profile derived from simulations and detailed X-ray analysis of
relaxed clusters to SZA observations of three clusters with exceptionally high
quality X-ray data: A1835, A1914, and CL J1226.9+3332. From the joint analysis
of the SZ and X-ray data, we derive physical properties such as gas mass, total
mass, gas fraction and the intrinsic, integrated Compton y-parameter. We find
that parameters derived from the joint fit to the SZ and X-ray data agree well
with a detailed, independent X-ray-only analysis of the same clusters. In
particular, we find that, when combined with X-ray imaging data, this new
pressure profile yields an independent electron radial temperature profile that
is in good agreement with spectroscopic X-ray measurements.


title:
Entanglement and control operations in Ising interactions of bipartite
  qubits

abstract:
  Entanglement generated by Ising model has been studied for several authors in
order to understand the relation between it and magnetic properties of
materials, principally using one or two dimensional models for two or more
particles. In this work, Ising model evolution is solved in three dimensions
for two parts including an inhomogeneous magnetic field, giving an detailed
study of the entanglement properties derived from interaction. Some relations
between entanglement and energy or spin are developed specifically to stablish
candidates for entanglement witness. Finally, some basic quantum control
operations are prescripted for this model as to preserve the properties of the
system as for transfer information between the two parts. These last schemes of
control are useful when initial state is completely known, to gain domain on
the system. It prevents to introduce more sophisticated control schemes which
normally are necessary when initial state is at least partially unknown.


title:
Coronal lines and dust formation in SN 2005ip: Not the brightest, but
  the hottest Type IIn supernova

abstract:
  We present optical photometry and spectroscopy of SN2005ip for the first 3yr
after discovery, showing an underlying Type II-L SN interacting with a steady
wind to yield an unusual Type IIn spectrum. For the first 160d, it had a fast
linear decline from a modest peak absolute magnitude of about -17.4
(unfiltered), followed by a plateau at roughly -14.8 for more than 2yr.
Initially having a normal broad-lined spectrum superposed with sparse narrow
lines from the photoionized CSM, it quickly developed signs of strong CSM
interaction with a spectrum similar to that of SN1988Z. As the underlying
SNII-L faded, SN2005ip exhibited a rich high-ionization spectrum with a dense
forest of narrow coronal lines, unprecedented among SNe but reminiscent of some
active galactic nuclei. The line-profile evolution of SN 2005ip confirms that
dust formation caused its recently reported infrared excess, but these lines
reveal that it is the first SN to show clear evidence for dust in both the fast
SN ejecta and the slower post-shock gas. SN2005ip's complex spectrum confirms
the origin of the strange blue continuum in SN2006jc, which also had post-shock
dust formation. We suggest that SN2005ip's late-time plateau and coronal
spectrum result from rejuvenated CSM interaction between a sustained fast shock
and a clumpy stellar wind, where X-rays escape through the optically thin
interclump regions to heat the pre-shock CSM to coronal temperatures.


title: Products of straight spaces

abstract:
  A metric space X is straight if for each finite cover of X by closed sets,
and for each real valued function f on X, if f is uniformly continuous on each
set of the cover, then f is uniformly continuous on the whole of X. A locally
connected space is straight if it is uniformly locally connected (ULC). It is
easily seen that ULC spaces are stable under finite products. On the other hand
the product of two straight spaces is not necessarily straight. We prove that
the product X x Y of two metric spaces is straight if and only if both X and Y
are straight and one of the following conditions holds: (a) both X and Y are
precompact; (b) both X and Y are locally connected; (c) one of the spaces is
both precompact and locally connected. In particular, when X satisfies (c), the
product X x Z is straight for every straight space Z. Finally, we characterize
when infinite products of metric spaces are ULC and we completely solve the
problem of straightness of infinite products of ULC spaces.


title:
The Carina Nebula: A Laboratory for Feedback and Triggered Star
  Formation

abstract:
  The Carina Nebula (NGC 3372) is our richest nearby laboratory in which to
study feedback through UV radiation and stellar winds from very massive stars
during the formation of an OB association, at an early phase before SNe have
disrupted the environment. This feedback is triggering new generations of star
formation around the periphery of the nebula, while simultaneously evaporating
the gas and dust reservoirs out of which young stars are trying to accrete.
Carina is currently powered by UV radiation from 65 O-type stars and 3 WNH
stars, but for most of its lifetime when its most massive star (Eta Car) was on
the main-sequence, the Carina Nebula was powered by 70 O-type stars that
produced an ionizing luminosity 150 times stronger than in Orion. At a distance
of 2.3 kpc, Carina has the most extreme stellar populationwithin a few kpc of
the Sun, and suffers little interstellar extinction. It is our best bridge
between the detailed star-formation processes that can be studied in nearby
regions like Orion, and much more extreme but also more distant regions like 30
Doradus. Existing observations have only begun to tap the tremendous potential
of this region for understanding the importance of feedback in star formation;
it will provide a reservoir of new discoveries for the next generation of large
ground-based telescopes, space telescopes, and large submillimeter and radio
arrays.


title: Metric groups attached to biextensions

abstract:
  Let $G$ be a connnected, unipotent, perfect group scheme over an
algebraically closed field of characteristic p > 0. V. Drinfeld has defined a
certain metric group associated to biextensions of $G \times G$ by the discrete
group $Q_p/Z_p$. We prove a certain conjecture of Drinfeld regarding the class
of this metric group in the Witt group.


abstract:
  The majority of astronomers and physicists accept the reality of dark energy
and also believe that it can only be studied indirectly through observation of
the motions of stars and galaxies. In this paper I open the experimental
question of whether it is possible to directly detect dark energy through the
presence of dark energy density. Two thirds of this paper outlines the major
aspects of dark energy density as now comprehended by the astronomical and
physics community. The final third summarizes various proposals for direct
detection of dark energy density or its possible effects. At this time I do not
have a fruitful answer to the question: Can the Existence of Dark Energy Be
Directly Detected?


title: Lie coalgebras and rational homotopy theory II: Hopf invariants

abstract:
  We give a new solution of the "homotopy periods" problem, as highlighted by
Sullivan, which places explicit geometrically meaningful formulae first dating
back to Whitehead in the context of Quillen's formalism for rational homotopy
theory and Koszul-Moore duality. Geometrically, we show that homotopy groups
are rationally given by "generalized linking/intersection invariants" of
cochain data. Moreover, we give a method for determining when two maps from
$S^n$ to $X$ are homotopic after allowing for multiplication by some integer.
For applications, we investigate wedges of spheres and homogeneous spaces
(where homotopy is given by classical linking numbers), and configuration
spaces (where homotopy is given by generalized linking numbers); also we
propose a generalization of the Hopf invariant one question.


title: Thermal entanglement in a molecular chain

abstract:
  We investigate entanglement in a linear chain of $N$ polar molecules coupled
by dipole interaction. In our model, nearest neighbour interaction predominate,
and we compute entanglement with the help of a two-party correlation
entanglement measure. We find that, in this system, only excited states are
entangled. Moreover, when an electrostatic field is applied, energy levels
crossings occur, changing significantly the system's entanglement properties.
We make a systematic study of the entanglement dependency on the inter
molecular distance separating pairs of molecules, different partitions of the
chain and physical parameters as the temperature and the electrostatic field's
intensity, showing that it persists for relatively high temperatures and
changes its nature with varying field.


title:
Contributions of charm anihilation to the hyperfine splitting in
  charmonium

abstract:
  In calculations of the hyperfine splitting in charmonium, the contributions
of the disconnected diagrams is considered small and is typically ignored. We
aim to estimate nonperturbatively the size of the resulting error, which could
potentially affect the high precision calculations of the charmonium spectrum.
Following our work on the effects of the disconnected diagrams in unquenched
QCD presented at Lattice 2007, we study the same problem in the quenched case.
On dynamical ensembles the disconnected charmonium propagators contain light
modes which complicate the extraction of the signal at large distances. In the
fully quenched case, where there are no such light modes, the interpretation of
the signal is simplified. We present results from lattices with $a\approx 0.09$
fm and $a\approx 0.063$ fm.


title: Hybrid Neural Network Architecture for On-Line Learning

abstract:
  Approaches to machine intelligence based on brain models have stressed the
use of neural networks for generalization. Here we propose the use of a hybrid
neural network architecture that uses two kind of neural networks
simultaneously: (i) a surface learning agent that quickly adapt to new modes of
operation; and, (ii) a deep learning agent that is very accurate within a
specific regime of operation. The two networks of the hybrid architecture
perform complementary functions that improve the overall performance. The
performance of the hybrid architecture has been compared with that of
back-propagation perceptrons and the CC and FC networks for chaotic time-series
prediction, the CATS benchmark test, and smooth function approximation. It has
been shown that the hybrid architecture provides a superior performance based
on the RMS error criterion.


title: Reeb vector fields and open book decompositions

abstract:
  We determine parts of the contact homology of certain contact 3-manifolds in
the framework of open book decompositions, due to Giroux. We study two cases:
when the monodromy map of the compatible open book is periodic and when it is
pseudo-Anosov. For an open book with periodic monodromy, we verify the
Weinstein conjecture. In the case of an open book with pseudo-Anosov monodromy,
suppose the boundary of a page of the open book is connected and the fractional
Dehn twist coefficient $c={k\over n}$, where $n$ is the number of prongs along
the boundary. If $k\geq 2$, then there is a well-defined linearized contact
homology group. If $k\geq 3$, then the linearized contact homology is
exponentially growing with respect to the action, and every Reeb vector field
of the corresponding contact structure admits an infinite number of simple
periodic orbits.


title:
Stationary Solutions of SPDEs and Infinite Horizon BDSDEs with
  Non-Lipschitz Coefficients

abstract:
  We prove a general theorem that the
$L_{\rho}^2({\mathbb{R}^{d}};{\mathbb{R}^{1}})\otimes
L_{\rho}^2({\mathbb{R}^{d}};{\mathbb{R}^{d}})$ valued solution of an infinite
horizon backward doubly stochastic differential equation, if exists, gives the
stationary solution of the corresponding stochastic partial differential
equation. We prove the existence and uniqueness of the
$L_{\rho}^2({\mathbb{R}^{d}};{\mathbb{R}^{1}})\otimes
L_{\rho}^2({\mathbb{R}^{d}};{\mathbb{R}^{d}})$ valued solutions for backward
doubly stochastic differential equations on finite and infinite horizon with
linear growth without assuming Lipschitz conditions, but under the monotonicity
condition. Therefore the solution of finite horizon problem gives the solution
of the initial value problem of the corresponding stochastic partial
differential equations, and the solution of the infinite horizon problem gives
the stationary solution of the SPDEs according to our general result.


title: Ultra-Compact Dwarf Candidates Near the Lensing Galaxy in Abell S0740

abstract:
  We analyze three-band HST/ACS imaging data of the giant elliptical galaxy
ESO325-G004. This is the nearest known strongly lensing galaxy, and it resides
in the center of the poor cluster Abell S0740 at redshift z=0.034. Based on
magnitude, color, and size selection criteria, we identify a sample of 15
ultra-compact dwarf (UCD) galaxy candidates within the ACS field. This is
comparable to the numbers of UCDs found within similar regions in more nearby
clusters (Virgo, Fornax, Hydra). We estimate circular half-light radii R_e,c
from 2-D Sersic and King model fits and apply an upper cutoff of 100pc for our
UCD selection. The selected galaxies have typical Sersic indices $n\approx1.5$,
while larger sources with R_e,c > 100pc are more nearly exponential, perhaps
indicating that the latter are dominated by background disk galaxies. Many of
the UCD candidates are surrounded by a faint "fuzz" of halo light, which may be
the remnants of stripped material, and there is some evidence for intrinsic
flattening of the UCDs themselves. An apparent separation in size between the
most compact UCDs with R_e,c < 17pc and larger ones with R_e,c > 40pc may hint
at different formation mechanisms. We do not find any M32 analogues in this
field. The colors of the UCD candidates span the range from blue to red
globular clusters, although the brightest ones are predominantly red. The UCD
candidates follow the flattened, elliptical distribution of the globular
clusters, which in turn follow the galaxy halo light, suggesting a common
evolution for these three components. Follow-up spectroscopy can determine
which candidates are truly members of Abell S0740 and how similar they are in
distribution to the globulars.


title: A convolution estimate for two-dimensional hypersurfaces

abstract:
  Given three transversal and sufficiently regular hypersurfaces in R^3 it
follows from work of Bennett-Carbery-Wright that the convolution of two L^2
functions supported of the first and second hypersurface, respectively, can be
restricted to an L^2 function on the third hypersurface, which can be
considered as a nonlinear version of the Loomis-Whitney inequality. We
generalize this result to a class of C^{1,beta} hypersurfaces in R^3, under
scaleable assumptions. The resulting uniform L^2 estimate has applications to
nonlinear dispersive equations.


title: Aspects of Unparticle Physics

abstract:
  We review some theoretical and experimental issues in unparticle physics,
focusing mainly on collider signatures.


title:
Observer Dependent Horizon Temperatures: a Coordinate-Free Formulation
  of Hawking Radiation as Tunneling

abstract:
  We reformulate the Hamilton-Jacobi tunneling method for calculating Hawking
radiation in static, spherically-symmetric spacetimes by explicitly
incorporating a preferred family of frames. These frames correspond to a family
of observers tied to a locally static timelike Killing vector of the spacetime.
This formulation separates the role of the coordinates from the choice of
vacuum and thus provides a coordinate-independent formulation of the tunneling
method. In addition, it clarifies the nature of certain constants and their
relation to these preferred observers in the calculation of horizon
temperatures. We first use this formalism to obtain the expected temperature
for a static observer at finite radius in the Schwarzschild spacetime. We then
apply this formalism to the Schwarzschild-de Sitter spacetime, where there is
no static observer with 4-velocity equal to the static timelike Killing vector.
It is shown that a preferred static observer, one whose trajectory is geodesic,
measures the lowest temperature from each horizon. Furthermore, this observer
measures horizon temperatures corresponding to the well-known Bousso-Hawking
normalization.


title: Free Fermionic Heterotic Model Building and Root Systems

abstract:
  We consider an alternative derivation of the GSO Projection in the free
fermionic construction of the weakly coupled heterotic string in terms of root
systems, as well as the interpretation of the GSO Projection in this picture.
We then present an algorithm to systematically and efficiently generate input
sets (i.e. basis vectors) in order to study Landscape statistics with minimal
computational cost. For example, the improvement at order 6 is approximately
10^{-13} over a traditional brute force approach, and improvement increases
with order. We then consider an example of statistics on a relatively simple
class of models.


title:
Analysis of the decay $B^0 \to \chi_{c1} \pi^0$ with light-cone QCD sum
  rules

abstract:
  In this article, we calculate the contribution from the nonfactorizable soft
hadronic matrix element to the decay $B^0\to \chi_{c1} \pi^0$ with the
light-cone QCD sum rules. The numerical results show that its contribution is
rather large and should not be neglected. The total amplitudes lead to a
branching fraction which is in agreement with the experimental data marginally.


title: Diversity Analysis of Bit-Interleaved Coded Multiple Beamforming

abstract:
  In this paper, diversity analysis of bit-interleaved coded multiple
beamforming (BICMB) is extended to the case of general spatial interleavers,
removing a condition on their previously known design criteria and quantifying
the resulting diversity order. The diversity order is determined by a parameter
Qmax which is inherited from the convolutional code and the spatial
de-multiplexer used in BICMB. We introduce a method to find this parameter by
employing a transfer function approach as in finding the weight spectrum of a
convolutional code. By using this method, several Qmax values are shown and
verified to be identical with the results from a computer search. The diversity
analysis and the method to find the parameter are supported by simulation
results. By using the Singleton bound, we also show that Qmax is lower bounded
by the product of the number of streams and the code rate of an encoder. The
design rule of the spatial de-multiplexer for a given convolutional code is
proposed to meet the condition on the maximum achievable diversity order.


title: Examples of buildings constructed via covering spaces

abstract: Covering space theory is used to construct new examples of buildings.


title: Polymer quantization, singularity resolution and the 1/r^2 potential

abstract:
  We present a polymer quantization of the -lambda/r^2 potential on the
positive real line and compute numerically the bound state eigenenergies in
terms of the dimensionless coupling constant lambda. The singularity at the
origin is handled in two ways: first, by regularizing the potential and
adopting either symmetric or antisymmetric boundary conditions; second, by
keeping the potential unregularized but allowing the singularity to be balanced
by an antisymmetric boundary condition. The results are compared to the
semiclassical limit of the polymer theory and to the conventional Schrodinger
quantization on L_2(R_+). The various quantization schemes are in excellent
agreement for the highly excited states but differ for the low-lying states,
and the polymer spectrum is bounded below even when the Schrodinger spectrum is
not. We find as expected that for the antisymmetric boundary condition the
regularization of the potential is redundant: the polymer quantum theory is
well defined even with the unregularized potential and the regularization of
the potential does not significantly affect the spectrum.


title: Mobility in Graphene Double Gate Field Effect Transistors

abstract:
  In this work, double-gated field effect transistors manufactured from
monolayer graphene are investigated. Conventional top-down CMOS-compatible
processes are applied except for graphene deposition by manual exfoliation.
Carrier mobilities in single- and double gated graphene field effect
transistors are compared. Even in double-gated graphene FETs, the carrier
mobility exceeds the universal mobility of silicon over nearly the entire
measured range. At comparable dimensions, reported mobilities for ultra thin
body silicon-on-insulator MOSFETs can not compete with graphene FET values.


title:
Star Formation Rates and Metallicities of K-selected Star Forming
  Galaxies at z~2

abstract:
  We present spectroscopy of 15 star-forming BzK galaxies (sBzKs) with K(AB)<23
in the Subaru Deep Field, for which Halpha and some other emission lines are
detected in 0.9 to 2.3 micron spectra with a resolution of R=500. Using Halpha
luminosities, we obtain star formation rates (SFRs), and then specific SFRs
(SSFRs) dividing SFRs by stellar masses, which are derived from SED fitting to
BVRi'z'K photometry. It is found that sBzKs with higher stellar masses have
larger SFRs. A negative correlation is seen between stellar mass and SSFR,
which is consistent with the previous results for z~2 galaxies. This implies
that a larger growth of stellar mass occurs in less massive galaxies. In
addition, gas-phase oxygen abundances, 12+log(O/H), are derived from the ratio
of NII(lambda 6584) to Halpha using the N2 index method. We have found a
correlation between stellar mass and oxygen abundance in the sense that more
massive sBzKs tend to be more metal rich, which is qualitatively consistent
with the relation for UV-selected z~2 galaxies. However, the metallicity of the
sBzKs is ~0.2 dex higher than that of UV-selected galaxies with similar stellar
masses, which is significant considering the small uncertainties. The sBzKs in
our sample have redder R-K colors than the UV-selected galaxies. This galaxy
color-dependence in the oxygen abundance may be caused by older or dustier
galaxies having higher metallicities at z~2.


title: Probability and complex quantum trajectories

abstract:
  It is shown that in the complex trajectory representation of quantum
mechanics, the Born's Psi^{\star}\Psi probability density can be obtained from
the imaginary part of the velocity field of particles on the real axis.
Extending this probability axiom to the complex plane, we first attempt to find
a probability density by solving an appropriate conservation equation. The
characteristic curves of this conservation equation are found to be the same as
the complex paths of particles in the new representation. The boundary
condition in this case is that the extended probability density should agree
with the quantum probability rule along the real line. For the simple,
time-independent, one-dimensional problems worked out here, we find that a
conserved probability density can be derived from the velocity field of
particles, except in regions where the trajectories were previously suspected
to be nonviable. An alternative method to find this probability density in
terms of a trajectory integral, which is easier to implement on a computer and
useful for single particle solutions, is also presented. Most importantly, we
show, by using the complex extension of Schrodinger equation, that the desired
conservation equation can be derived from this definition of probability
density.


title: Solutions of Backward Stochastic Differential Equations on Markov Chains

abstract:
  We consider backward stochastic differential equations (BSDEs) related to
finite state, continuous time Markov chains. We show that appropriate solutions
exist for arbitrary terminal conditions, and are unique up to sets of measure
zero. We do not require the generating functions to be monotonic, instead using
only an appropriate Lipschitz continuity condition.


title:
Upper Limits on the Masses of 105 Supermassive Black Holes from Hubble
  Space Telescope/Space Telescope Imaging Spectrograph Archival Data

abstract:
  Based on the modeling of the central emission-line width measured over
sub-arcsecond apertures with the Hubble Space Telescope, we present stringent
upper bounds on the mass of the central supermassive black hole, MBH, for a
sample of 105 nearby galaxies (D<100Mpc) spanning a wide range of Hubble types
(E-Sc) and values of the central stellar velocity dispersion, sigma
(58-419km/s). For the vast majority of the objects the derived MBH upper limits
run parallel and above the well-known MBH-sigma relation independently of the
galaxy distance, suggesting that our nebular line-width measurements trace
rather well the nuclear gravitational potential. For values of sigma between 90
and 220km/s the 68% of our upper limits falls immediately above the MBH-sigma
relation without exceeding the expected MBH values by more than a factor 4.1.
No systematic trends or offsets are observed in this sigma range as a function
of the galaxy Hubble type or with respect to the presence of a bar. For 6 of
our 12 MBH upper limits with sigma<90km/s our line-width measurements are more
sensitive to the stellar contribution to the gravitational potential, either
due to the presence of a nuclear stellar cluster or because of a greater
distance compared to the other galaxies at the low-sigma end of the MBH-sigma
relation. Conversely, our MBH upper bounds appear to lie closer to the expected
MBH in the most massive elliptical galaxies with values of sigma above 220km/s.
Such a flattening of the MBH-sigma relation at its high-sigma end would appear
consistent with a coevolution of supermassive black holes and galaxies driven
by dry mergers, although better and more consistent measurements for sigma and
K-band luminosity are needed for these kind of objects before systematic
effects can be ruled out.


title: The Spine of the Cosmic Web

abstract:
  We present the SpineWeb framework for the topological analysis of the Cosmic
Web and the identification of its walls, filaments and cluster nodes. Based on
the watershed segmentation of the cosmic density field, the SpineWeb method
invokes the local adjacency properties of the boundaries between the watershed
basins to trace the critical points in the density field and the separatrices
defined by them. The separatrices are classified into walls and the spine, the
network of filaments and nodes in the matter distribution. Testing the method
with a heuristic Voronoi model yields outstanding results. Following the
discussion of the test results, we apply the SpineWeb method to a set of
cosmological N-body simulations. The latter illustrates the potential for
studying the structure and dynamics of the Cosmic Web.


title:
Kinematics of planetary nebulae in the outskirts of the elliptical
  galaxy NGC 4697

abstract:
  We describe the implementation of slitless radial velocity measurements of
extragalactic planetary nebulae (PNs) with the 8.2 m Subaru telescope and its
Cassegrain imaging spectrograph, FOCAS. As a first application, we have
extended a previous search for PNs in NGC 4697 to larger angular distances from
its center. A total of 218 PNs were detected, and their radial velocities were
measured. We have added 56 new PN detections to the existing sample of 535,
observed previously with the ESO VLT + FORS imaging spectrograph; 36 of these
new 56 PNs are located at angular distances larger than 230 arcsec from the
center of NGC 4697. We compare the new FOCAS velocities with the earlier FORS
velocities, for 158 of the 162 reobserved sources, finding good agreement. We
now have kinematic information extending out to 5 effective radii from the
center. The outer line-of-sight velocity dispersion is a bit lower than
estimated earlier. This result is compatible with the existence of a dark
matter halo plus some degree of radial anisotropy, but the dark matter halo is
rather inconspicuous, and it is still unclear how massive it can be. A more
detailed global dynamical study of the whole set of PN velocities will be
required to decide if they permit to narrow down the range of possible dark
matter distributions in NGC 4697. The new radial velocities reveal no evidence
of rotation at 5 effective radii.


title: Giant Magnon and Spike Solutions with Two Spins in AdS4xCP3

abstract:
  In the string theory in AdS_4 \times CP^3 we construct the giant magnon and
spike solutions with two spins in two kinds of subspaces of R_t \times CP^3 and
derive the dispersion relations for them. For the single giant magnon solution
in one subspace we show that its dispersion relation is associated with that of
the big one-spin giant magnon solution in the RP^2 subspace. For the single
giant magnon solution in the other complementary subspace its dispersion
relation is similar to that of the one-spin giant magnon solution living in the
S^2 subspace but has one additional spin dependence.


title: Discovery of Extreme Carbon Stars in the Large Magellanic Cloud

abstract:
  Using Spitzer IRAC and MIPS observations of the Large Magellanic Cloud, we
have identified 13 objects that have extremely red mid-IR colors. Follow-up
Spitzer IRS observations of seven of these sources reveal varying amounts of
SiC and C2H2 absorption as well as the presence of a broad MgS feature in at
least two cases, indicating that these are extreme carbon stars. Preliminary
estimates find these objects have luminosities of 4-11x10^3 Lsol and
preliminary model fitting gives mass-loss rates between 4x10^-5 and 2x10^-4
Msol/yr, higher than any known carbon-rich AGB star in the LMC. These spectral
and physical properties require careful reconsideration of dust condensation
and mass-loss processes for carbon stars in low metallicity environments.


title:
The discontinuous nature of the exchange-correlation functional --
  critical for strongly correlated systems

abstract:
  Standard approximations for the exchange-correlation functional have been
found to give big errors for the linearity condition of fractional charges,
leading to delocalization error, and the constancy condition of fractional
spins, leading to static correlation error. These two conditions are now
unified for states with both fractional charge and fractional spin: the exact
energy functional is a plane, linear along the fractional charge coordinate and
constant along the fractional spin coordinate with a line of discontinuity at
the integer. This sheds light on the nature of the derivative discontinuity and
calls for explicitly discontinuous functionals of the density or orbitals that
go beyond currently used smooth approximations. This is key for the application
of DFT to strongly correlated systems.


title: On Q-factorial terminalizations of nilpotent orbits

abstract:
  In a recent preprint, Y. Namikawa proposed a conjecture on Q-factorial
terminalizations and their birational geometry of nilpotent orbits. He proved
his conjecture for classical simple Lie algebras. In this note, we prove his
conjecture for exceptional simple Lie algebras. For the birational geometry,
contrary to the classical case, two new types of Mukai flops appear.


title: Weighted sum formula for multiple zeta values

abstract:
  The sum formula is a basic identity of multiple zeta values that expresses a
Riemann zeta value as a homogeneous sum of multiple zeta values of a given
dimension. This formula was already known to Euler in the dimension two case,
conjectured in the early 1990s for higher dimensions and then proved by
Granville and Zagier independently. Recently a weighted form of Euler's formula
was obtained by Ohno and Zudilin. We generalize it to a weighted sum formula
for multiple zeta values of all dimensions.


title: Adiabatic hyperspherical study of triatomic helium systems

abstract:
  The 4He3 system is studied using the adiabatic hyperspherical representation.
We adopt the current state-of-the-art helium interaction potential including
retardation and the nonadditive three-body term, to calculate all low-energy
properties of the triatomic 4He system. The bound state energies of the 4He
trimer are computed as well as the 4He+4He2 elastic scattering cross sections,
the three-body recombination and collision induced dissociation rates at finite
temperatures. We also treat the system that consists of two 4He and one 3He
atoms, and compute the spectrum of the isotopic trimer 4He2 3He, the 3He+4He2
elastic scattering cross sections, the rates for three-body recombination and
the collision induced dissociation rate at finite temperatures. The effects of
retardation and the nonadditive three-body term are investigated. Retardation
is found to be significant in some cases, while the three-body term plays only
a minor role for these systems.


title: Extended Limber Approximation

abstract:
  We develop a systematic derivation for the Limber approximation to the
angular cross-power spectrum of two random fields, as a series expansion in
1/(\ell+1/2). This extended Limber approximation can be used to test the
accuracy of the Limber approximation and to improve the rate of convergence at
large \ell's. We show that the error in ordinary Limber approximation is
O(1/\ell^2). We also provide a simple expression for the second order
correction to the Limber formula, which improves the accuracy to O(1/\ell^4).
This correction can be especially useful for narrow redshift bins, or samples
with small redshift overlap, for which the zeroth order Limber formula has a
large error. We also point out that using \ell instead of (\ell+1/2), as is
often done in the literature, spoils the accuracy of the approximation to
O(1/\ell).


title:
Mutual Information and Boson Radius in c=1 Critical Systems in One
  Dimension

abstract:
  We study the generic scaling properties of the mutual information between two
disjoint intervals, in a class of one-dimensional quantum critical systems
described by the c=1 bosonic field theory. A numerical analysis of a spin-chain
model reveals that the mutual information is scale-invariant and depends
directly on the boson radius. We interpret the results in terms of correlation
functions of branch-point twist fields. The present study provides a new way to
determine the boson radius, and furthermore demonstrates the power of the
mutual information to extract more refined information of conformal field
theory than the central charge.

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


title: An Opinion Dynamics Model for the Diffusion of Innovations

abstract:
  We study the dynamics of the adoption of new products by agents with
continuous opinions and discrete actions (CODA). The model is such that the
refusal in adopting a new idea or product is increasingly weighted by neighbor
agents as evidence against the product. Under these rules, we study the
distribution of adoption times and the final proportion of adopters in the
population. We compare the cases where initial adopters are clustered to the
case where they are randomly scattered around the social network and
investigate small world effects on the final proportion of adopters. The model
predicts a fat tailed distribution for late adopters which is verified by
empirical data.


title: Classification of Local Singularities on Torus Curves of Type (2,5)

abstract:
  In this paper, we consider curves of degree 10 of torus type (2,5), C :
f_5(x, y)^2 + f_2(x, y)^5 = 0. Assume that f_2(0, 0) = f_5(0, 0) = 0. Then O =
(0, 0) is a singular point of C which is called an inner singularity. In this
paper, we give a topological classification of singularities of (C,O).


title:
A method to calculate correlation functions for $\beta=1$ random
  matrices of odd size

abstract:
  The calculation of correlation functions for $\beta=1$ random matrix
ensembles, which can be carried out using Pfaffians, has the peculiar feature
of requiring a separate calculation depending on the parity of the matrix size
N. This same complication is present in the calculation of the correlations for
the Ginibre Orthogonal Ensemble of real Gaussian matrices. In fact the methods
used to compute the $\beta=1$, N odd, correlations break down in the case of N
odd real Ginibre matrices, necessitating a new approach to both problems. The
new approach taken in this work is to deduce the $\beta=1$, N odd correlations
as limiting cases of their N even counterparts, when one of the particles is
removed towards infinity. This method is shown to yield the correlations for N
odd real Gaussian matrices.


title:
High Pressure studies of the magnetic phase transition in MnSi:
  revisited

abstract:
  New measurements of AC magnetic susceptibility and DC resistivity of a high
quality single crystal MnSi were carried out at high pressure making use of
helium as a pressure medium. The form of the AC magnetic susceptibility curves
at the magnetic phase transition suddenly changes upon helium solidification.
This implies strong sensitivity of magnetic properties of MnSi to non
hydrostatic stresses and suggests that the early claims on the existence of a
tricritical point at the phase transition line are probably a result of
misinterpretation of the experimental data. At the same time resistivity
behavior at the phase transition does not show such a significant influence of
helium solidification. The sharp peak at the temperature derivative of
resistivity, signifying the first order nature of the phase transition in MnSi
successfully survived helium crystallization and continued the same way to the
highest pressure.


title: Quantum Traces in Quantum Teichm\"uller Theory

abstract:
  We prove that for the torus with one hole and p greater than or equal to 1
punctures and the sphere with four holes there is a family of quantum trace
functions in the quantum Teichm\"uller space, analog to the non-quantum trace
functions in Teichm\"uller space, satisfying the properties proposed by Chekhov
and Fock in their paper "Observables in 3D Gravity and Geodesic Algebras."


title:
Multi-terminal Spin Transport: Non applicability of linear response and
  Equilibrium spin currents

abstract:
  We present generalized scattering theory for multi-terminal spin transport in
systems with broken SU(2) symmetry either due to spin-orbit
interaction,magnetic impurities or magnetic leads. We derive equation for spin
current consistent with charge conservation. It is shown that resulting spin
current equations can not be expressed as difference of potential pointing to
{\it non applicability of linear response for spin currents} and as a
consequence equilibrium spin currents(ESC) in the leads are non zero. We
illustrate the theory by calculating ESC in two terminal normal system in
presence of Rashba spin orbit coupling and show that it leads to spin
rectification consistent with the non linear nature of spin transport.


title: Proof of Riemann's zeta-hypothesis

abstract:
  Make an exponential transformation in the integral formulation of Riemann's
zeta-function zeta(s) for Re(s) > 0. Separately, in addition make the
substitution s -> 1 - s and then transform back to s again using the functional
equation. Using residue calculus, we can in this way get two alternative,
equivalent series expansions for zeta(s) of order N, both valid inside the
"critical strip", i e for 0 < Re(s) < 1. Together, these two expansions embody
important characteristics of the zeta-function in this range, and their
detailed behavior as N tends to infinity can be used to prove Riemann's
zeta-hypothesis that the nontrivial zeros of the zeta-function must all have
real part 1/2.
  In addition to the preprint, the arXiv file also contains a discussion of
some forty Frequently Asked Questions from readers. Further questions not
adequately dealt with in the existing FAQ are welcome.


title: Lowest-lying Tetra-Quark Hadrons in Anisotropic Lattice QCD

abstract:
  We present a detailed study of lowest-lying $q^{2}\bar{q}^{2}$ hadrons in
quenched improved anisotropic lattice QCD. Using the $\pi\pi$ and
diquark-antidiquark local and smeared operators, we attempt to isolate the
signal for $I(J^{P})=0(0^{+}), 2(0^{+})$ and $1(1^{+})$ states in two flavour
QCD. In the chiral limit of light-quark mass region, the lowest scalar $4q$
state is found to have a mass, $m^{I=0}_{4q}=927(12)$ MeV, which is slightly
lower than the experimentally observed $f_{0}(980)$. The results from our
variational analysis do not indicate a signature of a tetraquark resonance in
I=1 and I=2 channels. After the chiral extrapolation the lowest $1(1^{+})$
state is found to have a mass, $m^{I=1}_{4q}=1358(28)$ MeV. We analysed the
static $4q$ potential extracted form a tetraquark Wilson loop and illustrated
the behaviour of the $4q$ state as a bound state, unbinding at some critical
diquark separation. From our analysis we conclude that scalar $4q$ system
appears as a two-pion scattering state and that there is no spatially-localised
$4q$ state in the light-quark mass region.


abstract:
  We investigate the Galois coverings of weakly shod algebras. For a weakly
shod algebra not quasi-tilted of canonical type, we establish a correspondence
between its Galois coverings and the Galois coverings of its connecting
component. As a consequence, we show that a weakly shod algebra is simply
connected if and only if its first Hochschild cohomology group vanishes.


title: Root polytopes and growth series of root lattices

abstract:
  The convex hull of the roots of a classical root lattice is called a root
polytope. We determine explicit unimodular triangulations of the boundaries of
the root polytopes associated to the root lattices A_n, C_n, and D_n, and
compute their f-and h-vectors. This leads us to recover formulae for the growth
series of these root lattices, which were first conjectured by
Conway-Mallows-Sloane and Baake-Grimm and proved by Conway-Sloane and Bacher-de
la Harpe-Venkov.


title: Cosmology from very high energy $\gamma$-rays

abstract:
  In this work we study how the cosmological parameter, the Hubble constant
$H_0$, can be constrained by observation of very high energy (VHE)
$\gamma$-rays at the TeV scale. The VHE $\gamma$-rays experience attenuation by
background radiation field through $e^+e^-$ pair production during the
propagation in the intergalactic space. This effect is proportional to the
distance that the VHE $\gamma$-rays go through. Therefore the absorption of TeV
$\gamma$-rays can be taken as cosmological distance indicator to constrain the
cosmological parameters. Two blazars Mrk 501 and 1ES 1101-232, which have
relatively good spectra measurements by the atmospheric Cerenkov telescope, are
studied to constrain $H_0$. The mechanism constraining the Hubble constant
adopted here is very different from the previous methods such as the
observations of type Ia supernovae and the cosmic microwave background.
However, at $2\sigma$ level, our result is consistent with other methods.


title: Bundle Gerbes for Orientifold Sigma Models

abstract:
  Bundle gerbes with connection and their modules play an important role in the
theory of two-dimensional sigma models with a background Wess-Zumino flux:
their holonomy determines the contribution of the flux to the Feynman
amplitudes of classical fields. We discuss additional structures on bundle
gerbes and gerbe modules needed in similar constructions for orientifold sigma
models describing closed and open strings.


title: CdWO4 bolometers for Double Beta Decay search

abstract:
  In the field of Double Beta Decay (DBD) searches the possibility to have high
resolution detectors in which background can be discriminated is very
appealing. This very interesting possibility can be largely fulfilled in the
case of a scintillating bolometer containing a Double Beta Decay emitter whose
transition energy exceeds the one of the natural gamma line of 208Tl. We
present the latest results obtained in the development of such a kind of
scintillating bolometer. For the first time an array of five CdWO4 (116Cd has a
Double Beta Decay transition energy of 2805 keV) crystals is tested. The array
consists of a plane of four 3x3x3 cm3 crystals and a second plane consisting of
a single 3x3x6 cm3 crystal. This setup is mounted in hall C of the National
Laboratory of Gran Sasso inside a lead shielding in order to reduce as far as
possible the environmental background. The aim of this test is to demonstrate
the technical feasibility of this technique through an array of detectors and
perform a long background measurement in the best conditions in order to prove
the achievable background in the Zero neutrino-DBD region.


title:
Rashba type spin-orbit splitting of quantum well states in ultrathin Pb
  films

abstract:
  A Rashba type spin-orbit splitting is found for quantum well states formed in
ultrathin Pb films on Si(111). The resulting momentum splitting is comparable
to what is found for semiconductor heterostructures. The splitting shows no
coverage dependency and the sign of the spin polarization is reversed compared
to Rashba splitting in the Au(111) surface state. We explain our results by
competing effects at the two boundaries of the Pb layer.


title:
Evidence of spin density wave in LaFeAsO, the parent material of the new
  Fe-based oxypnictide superconductors

abstract:
  The Fe-based Oxypnicide superconductors have generated a huge amount of
interest; they are a high temperature superconductor, with a Tc of 55K, but do
not have the two dimensional copper oxygen layer that was thought essential for
superconductivity at these high temperatures. Initial studies have hinted
towards the possibility of a spin density wave (SDW) in these compounds and how
they could play an important role in the superconductivity. SDW's occur at low
temperatures in low-dimensional materials with strong electron correlations or
in metals with a high density of states at the Fermi surface. A transition to
the SDW state has many similarities to the superconducting transition, driven
by the condensation energy with an energy gap opening, and in many materials
the SDW state occurs adjacent in the phase diagram to the superconducting
state. In these materials it is believed that electron doping suppresses the
SDW instability allowing superconductivity to emerge. In this paper we report
on the first direct experimental evidence of a SDW in the LaFeAsO parent
compound as observed with inelastic neutron scattering. We show that these
excitation derive from a two-dimensional Fermi surface nesting with a nesting
vector of (\pi,\pi,0).


title:
The neutrino signal from protoneutron star accretion and black hole
  formation

abstract:
  We discuss the formation of stellar mass black holes via protoneutron star
(PNS) collapse. In the absence of an earlier explosion, the PNS collapses to a
black hole due to the continued mass accretion onto the PNS. We present an
analysis of the emitted neutrino spectra of all three flavors during the PNS
contraction. Special attention is given to the physical conditions which depend
on the input physics, e.g. the equation of state (EoS) and the progenitor
model. The PNSs are modeled as the central object in core collapse simulations
using general relativistic three-flavor Boltzmann neutrino transport in
spherical symmetry. The simulations are launched from several massive
progenitors of 40 and 50 solar mass. We analyze the electron-neutrino
luminosity dependencies and construct a simple approximation for the
electron-neutrino luminosity, which depends only on the physical conditions at
the electron-neutrinosphere. In addition, we analyze different mu/tau-neutrino
pair-reactions separately and compare the differences during the post-bounce
phase of failed core collapse supernova explosions of massive progenitors. We
also investigate the connection between the increasing mu/tau-neutrino
luminosity and the PNS contraction during the accretion phase before black hole
formation. Comparing the different post bounce phase of the progenitor models
under investigation, we find large differences in the emitted neutrino spectra.
These differences and the analysis of the electron-neutrino luminosity indicate
a strong progenitor model dependency of the emitted neutrino signal.


title: Decomposing the Essential Spectrum

abstract:
  We use C*-algebra theory to provide a new method of decomposing the eseential
spectra of self-adjoint and non-self-adjoint Schrodinger operators in one or
more space dimensions.


title: Chemically peculiar stars and their temperature calibration

abstract:
  The determination of effective temperature for chemically peculiar (CP) stars
by means of photometry is a sophisticated task due to their abnormal colours.
Standard calibrations for normal stars lead to erroneous results and, in most
cases corrections are necessary. In order to specify appropriate corrections,
direct temperature determinations for 176 objects of the different subgroups
were collected from the literature. This much larger sample than in previous
studies therefore allows a more accurate investigation, mostly based on average
temperatures. For the three main photometric systems (UBV, Geneva, Stromgren
uvbybeta), methods to determine effective temperature are presented together
with a comparison with former results. Based on the compiled data we provide
evidence that He (CP4) objects also need a considerable correction, not noticed
in former investigations due to their small number. Additionally, a new
relation for the bolometric correction and the capability of standard
calibrations to deduce interstellar reddening for magnetic CP stars are shown.


title:
A Constraint on brown dwarf formation via ejection: radial variation of
  the stellar and substellar mass function of the young open cluster IC2391

abstract:
  Using the Wide Field Imager (WFI) at the ESO 2.2m telescope at La Silla and
the CPAPIR camera at the CTIO 1.5m telescope at Cerro Tololo, we have performed
an extensive, multiband photometric survey of the open cluster IC2391 (D~146pc,
age~50Myr, solar metallicity). Here we present the results from our photometric
survey and from a spectroscopic follow-up of the central part of the survey.


title: The Time Projection Chamber for the ALICE Experiment

abstract:
  The Time Projection Chamber of the ALICE Experiment has been installed in the
experimental setup in the underground area at the Large Hadron Collider at CERN
in Geneva. The Alice TPC ReadOut (ALTRO) chip implements intelligent signal
processing on the Front-End-Electronics. During the years of 2007 and 2008
commissioning and calibration of the TPC have been carried out with cosmic
rays, radioactive Krypton isotopes and with tracks produced by a UV laser
system. In addition to these in this publication we present first results on
energy loss measurements and on the momentum resolution.