title: Why devil plays dice?

abstract:
  Principle of Relativity involving all, not only subluminal, inertial frames
leads to the disturbance of causal laws in a way known from the fundamental
postulates of Quantum Theory. We show how quantum indeterminacy based on
complex probability amplitudes with superposition principle emerges from
Special Relativity.


title:
Inconsistency of the judgment matrix in the AHP method and the decision
  maker's knowledge

abstract:
  In this paper we propose a method for a quantitative estimation of the
decision maker's knowledge in the context of the Analytic Hierarchy Process
(AHP) in cases, where the judgment matrix is inconsistent. We show that the
matrix of deviation from the transitivity condition corresponds to the rate
matrix for transaction costs in the financial market. For the quantitative
estimation of the decision maker's professionalism, we apply the Ising model
and thermodynamics tools.


title: Quantum Critical Behaviour in a Graphene-like Model

abstract:
  We present the first results of numerical simulations of a 2+1 dimensional
fermion field theory based on a recent proposal for a model of graphene,
consisting of N_f four-component Dirac fermions moving in the plane and
interacting via an instantaneous Coulomb interaction. In the strong-coupling
limit we identify a critical number of flavors N_fc=4.8(2) separating an
insulating from a conducting phase. This transition corresponds to the location
of a quantum critical point, and we use a fit to the equation of state for the
chiral order parameter to estimate the critical exponents. Next we simulate
N_f=2 corresponding to real graphene, and approximately locate a transition
from strong to weak coupling behaviour. Strong correlations are evident in the
weak-coupling regime.


title: Self-similar Focusing in Porous Media: An Explicit Calculation

abstract:
  We consider a porous mediaum flow in which the gas is initially distributed
in the exterior of an empty region (a hole) and study the final stage of the
hole-filling process. Hole-filling is asymptotically described by a
self-similar solution which depends on a constant determined by the initial
configuration. In general, this constant must be found numerically.. Here we
give an example of a one-dimensional symmetric flow where the constant is
obtained explicitly.


title: The transverse angular momentum sum rule

abstract:
  We explain the origin of the controversy about the existence of a transverse
angular momentum sum rule, and show that it stems from utilizing an incorrect
result in the literature, concerning the expression for the expectation values
of the angular momentum operators. We demonstrate a new, short and direct way
of obtaining correct expressions for these expectation values, from which a
perfectly good transverse angular momentum sum rule can be deduced. We also
introduce a new classification of sum rules into primary and secondary types.
In the former all terms occurring in the sum rule can be measured
experimentally; in the latter some terms cannot be measured experimentally.


title: The Role of Second Trials in Cascades of Information over Networks

abstract:
  We study the propagation of information in social networks. To do so, we
focus on a cascade model where nodes are infected with {probability $p_1$ after
their first contact with the information and with probability $p_2$ at all
subsequent contacts.} The diffusion starts from one random node and leads to a
cascade of infection. It is shown that first and {subsequent} trials play
different roles in the propagation and that the size of the cascade depends in
a non-trivial way on $p_1$, $p_2$ and on the network structure. Second trials
are shown to amplify the propagation in dense parts of the network while first
trials are {dominant for the exploration of} new parts of the network and
launching new seeds of infection.


title: Geometry of syzygies via Poncelet varieties

abstract:
  We consider the Grassmannian $\mathbb{G}r(k,n)$ of $(k+1)$-dimensional linear
subspaces of $V_n=H^0({\P^1},\O_{\P^1}(n))$. We define $\frak{X}_{k,r,d}$ as
the classifying space of the $k$-dimensional linear systems of degree $n$ on
$\P^1$ whose basis realize a fixed number of polynomial relations of fixed
degree, say a fixed number of syzygies of a certain degree. The first result of
this paper is the computation of the dimension of $\frak{X}_{k,r,d}$. In the
second part we make a link between $\frak{X}_{k,r,d}$ and the Poncelet
varieties. In particular, we prove that the existence of linear syzygies
implies the existence of singularities on the Poncelet varieties.


title: Origin of the Temperature Oscillation in Turbulent Thermal Convection

abstract:
  We report an experimental study of the three-dimensional spatial structure of
the low frequency temperature oscillations in a cylindrical Rayleigh-B\'{e}nard
convection cell. It is found that thermal plumes are not emitted periodically,
but randomly and continuously, from the top and bottom plates. We further found
that the oscillation of the temperature field does not originate from the
boundary layers, but rather is a result of the horizontal motion of the hot
ascending and cold descending fluids being modulated by the twisting and
sloshing motion of the bulk flow field.


title:
Probing the order-to-chaos region in superdeformed 151Tb and 196Pb
  nuclei with continuum gamma-transitions

abstract:
  The gamma-decay associated with the warm rotation of the superdeformed (SD)
nuclei 151Tb and 196Pb has been measured with the EUROBALL IV array. Several
independent quantities provide a stringent test of the population and decay
dynamics in the SD well. A Monte Carlo simulation of the gamma-decay based on
microscopic calculations gives remarkable agreement with the data only assuming
a large enhancement of the B(E1) strength at low excitation energy, which may
be related to the evidence for octupole vibrations in both mass regions.


title: Quantum chaos in disordered graphene

abstract:
  We have studied numerically the statistics for electronic states
(level-spacings and participation ratios) from disordered graphene of finite
size, described by the aspect ratio $W/L$ and various geometries, including
finite or torroidal, chiral or achiral carbon nanotubes. Quantum chaotic Wigner
energy level-spacing distribution is found for weak disorder, even
infinitesimally small disorder for wide and short samples ($W/L>>1$), while for
strong disorder Anderson localization with Poisson level-statistics always sets
in. Although pure graphene near the Dirac point corresponds to integrable
ballistic statistics chaotic diffusive behavior is more common for realistic
samples.


title:
Instability results for an elliptic equation on compact Riemannian
  manifolds with non-negative Ricci curvature

abstract:
  We prove nonexistence of nonconstant local minimizers for a class of
functionals, which typically appears in the scalar two-phase field model, over
a smooth N-dimensional Riemannian manifold without boundary with non-negative
Ricci curvature. Conversely for a class of surfaces possessing a simple closed
geodesic along which the Gauss curvature is negative we prove existence of
nonconstant local minimizers for the same class of functionals.


title: Single top quark photoproduction at the LHC

abstract:
  High-energy photon-proton interactions at the LHC offer interesting
possibilities for the study of the electroweak sector up to TeV scale and
searches for processes beyond the Standard Model. An analysis of the W
associated single top photoproduction has been performed using the adapted
MadGraph/MadEvent and CalcHEP programs interfaced to the Pythia generator and a
fast detector simulation program. Event selection and suppression of main
backgrounds have been studied. A comparable sensitivity to |V_{tb}| to those
obtained using the standard single top production in pp collisions has been
achieved already for 10 fb^{-1} of integrated luminosity. Photoproduction at
the LHC provides also an attractive framework for observation of the anomalous
production of single top due to Flavour-Changing Neutral Currents. The
sensitivity to anomalous coupling parameters, k_{tu\gamma} and k_{tc\gamma} is
presented and indicates that stronger limits can be placed on anomalous
couplings after 1 fb^{-1}.


title: Visualization Drivers for Geant4

abstract:
  This document is on Geant4 visualization tools (drivers), evaluating pros and
cons of each option, including recommendations on which tools to support at
Fermilab for different applications{\cite{Daniel}}.
  Four visualization drivers are evaluated. They are OpenGL, HepRep, DAWN and
VRML. They all have good features, OpenGL provides graphic output with out an
intermediate file! HepRep provides menus to assist the user. DAWN provides high
quality plots and even for large files produces output quickly. VRML uses the
smallest disk space for intermediate files.
  Large experiments at Fermilab will want to write their own display. They
should proceed to make this display graphics independent. Medium experiment
will probably want to use HepRep because of it's menu support. Smaller scale
experiments will want to use OpenGL in the spirit of having immediate response,
good quality output and keeping things simple.


title: Scanning strategies for imaging arrays

abstract:
  Large-format (sub)millimeter wavelength imaging arrays are best operated in
scanning observing modes rather than traditional position-switched (chopped)
modes. The choice of observing mode is critical for isolating source signals
from various types of noise interference, especially for ground-based
instrumentation operating under a bright atmosphere. Ideal observing strategies
can combat 1/f noise, resist instrumental defects, sensitively recover emission
on large scales, and provide an even field coverage -- all under feasible
requirements of telescope movement. This work aims to guide the design of
observing patterns that maximize scientific returns. It also compares some of
the popular choices of observing modes for (sub)millimeter imaging, such as
random, Lissajous, billiard, spiral, On-The-Fly (OTF), DREAM, chopped and stare
patterns. Many of the conclusions are also applicable other imaging
applications and imaging in one dimension (e.g. spectroscopic observations).


title: Splitting of a Cooper pair by a pair of Majorana bound states

abstract:
  Majorana bound states are spatially localized superpositions of electron and
hole excitations in the middle of a superconducting energy gap. A single qubit
can be encoded nonlocally in a pair of spatially separated Majorana bound
states. Such Majorana qubits are in demand as building blocks of a topological
quantum computer, but direct experimental tests of the nonlocality remain
elusive. Here we propose a method to probe the nonlocality by means of crossed
Andreev reflection, which is the injection of an electron into one bound state
followed by the emission of a hole by the other bound state (equivalent to the
splitting of a Cooper pair over the two states). We have found that, at
sufficiently low excitation energies, this nonlocal scattering process
dominates over local Andreev reflection involving a single bound state. As a
consequence, the low-temperature and low-frequency fluctuations $\delta I_{i}$
of currents into the two bound states $i=1,2$ are maximally correlated:
$\overline{\delta I_{1}\delta I_{2}}=\overline{\delta I_{i}^{2}}$.


title: Recent Progress in Global PDF Analysis

abstract:
  We discuss selected topics in the forthcoming MSTW 2008 determination of
parton distributions by global analysis. The tolerance parameter controlling
the uncertainties on the parton distributions is now determined by a new
dynamic procedure for each eigenvector of the covariance matrix. New data sets
fitted include Tevatron Run II data on inclusive jet production, the lepton
charge asymmetry from W decays and the Z rapidity distribution. Predictions are
given for the total W and Z cross sections at the Tevatron and LHC.


title: On the Boltzmann-Grad Limit for the classical hard-spheres system

abstract:
  Despite the progress achieved by kinetic theory, the search of possible exact
kinetic equations remains elusive to date. This concerns, specifically, the
issue of the validity of the conjecture proposed by Grad (Grad, 1972) and
developed in a seminal work by Lanford (Lanford, 1974) that kinetic equations -
such as the Boltzmann equation for a gas of classical hard spheres - might
result exact in an appropriate asymptotic limit, usually denoted as
Boltzmann-Grad limit. The Lanford conjecture has actually had a profound
influence on the scientific community, giving rise to a whole line of original
research in kinetic theory and mathematical physics. Nevertheless, certain
aspects of the theory remain to be addressed and clarified. The purpose of this
paper is to investigate the possible existence of the strong Boltzmann-Grad
limit for the BBGKY hierarchy. Contrary to previous approaches in which the
w*-convergence was considered for the definition of the Boltzmann-Grad limit
functions, based on their construction in terms of time-series expansions
obtained from the BBGKY hierarchy, here we look for the possible existence of
strong limit functions in the sense of local convergence in phase space. The
result is based on the adoption of the Klimontovich approach to statistical
mechanics, permitting the explicit representation of the $s$-body reduced
distribution functions in terms of the Klimontovich probability density.


title: GD 552: a cataclysmic variable with a brown dwarf companion?

abstract:
  GD 552 is a high proper motion star with the strong, double-peaked emission
lines characteristic of the dwarf nova class of cataclysmic variable star, and
yet no outburst has been detected during the past 12 years of monitoring. We
present spectroscopy taken with the aim of detecting emission from the mass
donor in this system. We fail to do so at a level which allows us to rule out
the presence of a near-main-sequence star donor. Given GD 552's orbital period
of 103 minutes, this suggests that it is either a system that has evolved
through the ~80-minute orbital period minimum of cataclysmic variable stars and
now has a brown dwarf mass donor, or that has formed with a brown dwarf donor
in the first place. This model explains the low observed orbital velocity of
the white dwarf and GD 552's low luminosity. It is also consistent with the
absence of outbursts from the system.


title:
Role of the Mean-field in Bloch Oscillations of a Bose-Einstein
  Condensate in an Optical Lattice and Harmonic Trap

abstract:
  Using the Crank-Nicholson method, we study the evolution of a Bose-Einstein
condensate in an optical lattice and harmonic trap. The condensate is excited
by displacing it from the center of the harmonic trap. The mean field plays an
important role in the Bloch-like oscillations that occur after sufficiently
large initial displacement. We find that a moderate mean field significantly
suppresses the dispersion of the condensate in momentum space. When the mean
field becomes large, soliton and vortex structures appear in the condensate
wavefunction.


title: Multiperiodic RR Lyrae Stars in Omega Centauri

abstract:
  We have conducted a systematic search for multiperiodic pulsations in the RR
Lyrae-type stars of the galactic globular cluster Omega Cen. Secondary
periodicities close to the primary pulsation frequency have been detected in 17
out of 70 studied fundamental mode (RRab) pulsators and in 35 out of 81
overtone (RRc) pulsators. Because of the observed period ratios, these newly
detected periodicities must correspond to nonradial modes. Their beating with
the primary radial pulsation leads to a slow amplitude and phase modulation,
commonly referred to as the Blazhko effect. The incidence rate of Blazhko
modulation in Omega Cen RRab stars (24 +/- 5%) is similar to that observed in
the Galactic Bulge. In the case of Omega Cen RRc stars, the incidence rate of
Blazhko effect is exceptionally high (38 +/- 5%), more than 3 times higher than
in any other studied population.
  In addition to Blazhko variables, we have also identified two RR Lyr
variables exhibiting first overtone/second overtone double-mode pulsations, and
a triple-mode High Amplitude Delta Scuti variable.


title: Collective Excitations of Harmonically Trapped Ideal Gases

abstract:
  We theoretically study the collective excitations of an ideal gas confined in
an isotropic harmonic trap. We give an exact solution to the Boltzmann-Vlasov
equation; as expected for a single-component system, the associated mode
frequencies are integer multiples of the trapping frequency. We show that the
expressions found by the scaling ansatz method are a special case of our
solution. Our findings, however, are most useful in case the trap contains more
than one phase: we demonstrate how to obtain the oscillation frequencies in
case an interface is present between the ideal gas and a different phase.


title:
Exclusive scalar glueball $f_0(1500)$ production for FAIR and J-PARC
  energy range

abstract:
  We evaluate differential distributions for exclusive scalar $f_0(1500)$
production for $p \bar p \to N_1 N_2 f_0$ (FAIR@GSI) and $p p \to p p f_0$
(J-PARC@Tokai). Both QCD diffractive and pion-pion meson exchange current (MEC)
components are included. Rather large cross sections are predicted. The
pion-pion component, never discussed in the literature, dominates close to the
threshold while the diffractive component takes over for larger energies. The
diffractive component is calculated based on two-gluon impact factors as well
as in the framework of Khoze-Martin-Ryskin approach proposed for diffractive
Higgs boson production. Different unintegrated gluon distribution functions
(UGDFs) from the literature are used. The production of $f_0(1500)$ close to
threshold could limit the so-called $\pi NN$ form factor in the region of
larger pion virtualities.


title:
Suppression of non-adiabatic phases by a non-Markovian environment:
  easier observation of Berry phases

abstract:
  We consider a two-level system coupled to a highly non-Markovian environment
when the coupling axis rotates with time. The environment may be quantum (for
example a bosonic bath or a spin bath) or classical (such as classical noise).
We show that an Anderson orthogonality catastrophe suppresses transitions, so
that the system's instantaneous eigenstates (parallel and anti-parallel to the
coupling axis) can adiabatically follow the rotation. These states thereby
acquire Berry phases; geometric phases given by the area enclosed by the
coupling axis. Unlike in earlier proposals for environment-induced Berry
phases, here there is little decoherence, so one does not need a
decoherence-free subspace. Indeed we show that this Berry phase should be much
easier to observe than a conventional one, because it is not masked by either
the dynamic phase or the leading non-adiabatic phase. The effects that we
discuss should be observable in any qubit device where one can drive three
parameters in the Hamiltonian with strong man-made noise.


title: Bound States in the Continuum in Two-Dimensional Serial Structures

abstract:
  We investigate the occurrence of bound states in the continuum (BIC's) in
serial structures of quantum dots coupled to an external waveguide, when some
characteristic length of the system is changed. By resorting to a multichannel
scattering-matrix approach, we show that BIC's do actually occur in
two--dimensional serial structures, and that they are a robust effect. When a
BIC is produced in a two--dot system, it also occurs for several coupled dots.
We also show that the complex dependence of the conductance upon the geometry
of the device allows for a simple picture in terms of the resonance pole motion
in the multi--sheeted Riemann energy surface. Finally, we show that in
correspondence to a zero--width state for the open system one has a multiplet
of degenerate eigenenergies for the associated closed serial system, thereby
generalizing results previously obtained for single dots and two-dot devices.


title: A Dynamic Programming Approach To Length-Limited Huffman Coding

abstract:
  The ``state-of-the-art'' in Length Limited Huffman Coding algorithms is the
$\Theta(ND)$-time, $\Theta(N)$-space one of Hirschberg and Larmore, where $D\le
N$ is the length restriction on the code. This is a very clever, very problem
specific, technique. In this note we show that there is a simple
Dynamic-Programming (DP) method that solves the problem with the same time and
space bounds. The fact that there was an $\Theta(ND)$ time DP algorithm was
previously known; it is a straightforward DP with the Monge property (which
permits an order of magnitude speedup). It was not interesting, though, because
it also required $\Theta(ND)$ space. The main result of this paper is the
technique developed for reducing the space. It is quite simple and applicable
to many other problems modeled by DPs with the Monge property. We illustrate
this with examples from web-proxy design and wireless mobile paging.


title: A note on Quantum Aspects of Multiple Membranes

abstract:
  In this note we investigate quantum aspects of the newly proposed theory of
multiple membranes put forward by Bagger and Lambert. In particular we analyse
the possibility of a finite renormalisation of the coupling at one loop.


title:
Selected vector-meson decay-distributions in reactions of polarized
  photons with protons

abstract:
  We develop a formalism for studying vector meson ($V$) photo-production at
the proton ($p$) with polarized photons, $\vec\gamma p \to V p $, through an
analysis of the decay distribution in the channel $V\to\pi^0\gamma$. We show
that this decay distribution differs noticeably from the distributions of
purely hadronic decays, like $\phi\to K^+K^-$, $\omega\to \pi^0\pi^+\pi^-$.
Formulas for the decay distributions are presented which are suitable for data
analysis and interpretation.


title: Smoothing Effects for Navier-Stokes Equations

abstract:
  We prove some smoothing effects for the 3-D Navier-Stokes equations for
initial data belonging to the critical Sobolev space $H^{1/2}(\R^3)$.
Asymptotic behavior of the global solution when the time goes to infinity is
studied. We also obtain a new energy estimate. Other results in this direction
and with different methods can be found in \cite{C4}.


title: Asymptotic Analysis of MHD Systems

abstract:
  In this paper, we study the convergence of strong solutions of a
Magneto-Hydro-Dynamic system. On the torus ${\mathbb{T}}^3$, the proof is based
on Schochet's methods, whereas in the case of the whole space ${\bf
\mathbb{R}^3}$, we use Strichartz's type estimates and a product law's
$2D\times3D$.


title:
Direct Detection of the Close Companion of Polaris with the Hubble Space
  Telescope

abstract:
  Polaris, the nearest and brightest classical Cepheid, is a single-lined
spectroscopic binary with an orbital period of 30 years. Using the High
Resolution Channel of the Advanced Camera for Surveys onboard the Hubble Space
Telescope (HST) at a wavelength of ~2255\AA, we have directly detected the
faint companion at a separation of 0\farcs17. A second HST observation 1.04 yr
later confirms orbital motion in a retrograde direction. By combining our two
measures with the spectroscopic orbit of Kamper and an analysis of the
Hipparcos and FK5 proper motions by Wielen et al., we find a mass for Polaris
Aa of 4.5^{+2.2}_{-1.4} M_\odot--the first purely dynamical mass determined for
any Cepheid. For the faint companion Polaris Ab we find a dynamical mass of
1.26^{+0.14}_{-0.07} M_\odot, consistent with an inferred spectral type of F6 V
and with the flux difference of 5.4 mag observed at 2255\AA. The magnitude
difference at the V band is estimated to be 7.2 mag. Continued HST observations
will significantly reduce the mass errors, which are presently still too large
to provide critical constraints on the roles of convective overshoot, mass
loss, rotation, and opacities in the evolution of intermediate-mass stars.
  Our astrometry, combined with two centuries of archival measurements, also
confirms that the well-known, more distant (18") visual companion, Polaris B,
has a nearly common proper motion with that of the Aa,Ab pair. This is
consistent with orbital motion in a long-period bound system. The ultraviolet
brightness of Polaris B is in accordance with its known F3 V spectral type if
it has the same distance as Polaris Aa,Ab.


title: Two-Loop QED Heavy-Flavor Contribution to Bhabha Scattering

abstract:
  We briefly review the status of the calculation of next-to-next-to-leading
order corrections to large angle Bhabha scattering in pure QED. In particular,
we focus on the analytic calculation of the two-loop virtual corrections
involving a heavy-flavor fermion loop, which was recently completed. We
conclude by assessing the numerical impact of these corrections on the Bhabha
scattering cross section at colliders operating at a center of mass energy of 1
GeV and at the future ILC.


title:
An Infinite Number of Static Soliton Solutions to the 5D
  Einstein-Maxwell Equations with a Dilaton Field

abstract:
  We study the 5D static Einstein-Maxwell equations with a dilaton field. We
construct an infinte number of solutions by using a soliton technique. We study
the rod structure of 2-soliton solution and show the 5D dilatonic black ring
and black hole solutions are included.


title: The Problem with the Linpack Benchmark Matrix Generator

abstract:
  We characterize the matrix sizes for which the Linpack Benchmark matrix
generator constructs a matrix with identical columns.


title:
The effect of local dipole moments on the structure and lattice dynamics
  of K0.98Li0.02TaO3

abstract:
  We present high energy x-ray (67 keV) and neutron scattering measurements on
a single crystal of K$_{1-x}$Li$_x$TaO$_3$ for which the Li content ($x=0.02$)
is less than $x_c = 0.022$, the critical value below which no structural phase
transitions have been reported in zero field. While the crystal lattice does
remain cubic down to T=10 K under both zero-field and field-cooled ($E \le 4$
kV/cm) conditions, indications of crystal symmetry lowering are seen at
$T_C=63$ K where the Bragg peak intensity changes significantly. A strong and
frequency-dependent dielectric permittivity is observed at ambient pressure, a
defining characteristic of relaxors. However an extensive search for static
polar nanoregions, which is also widely associated with relaxor materials,
detected no evidence of elastic neutron diffuse scattering between 300 K and 10
K. Neutron inelastic scattering methods were used to characterize the
transverse acoustic and optic phonons (TA1 and TO1 modes) near the (200) and
(002) Bragg peaks. The zone center TO1 mode softens monotonically with cooling
but never reaches zero energy in either zero field or in external electric
fields of up to 4 kV/cm. These results are consistent with the behavior
expected for a dipolar glass in which the local polar moments are frozen and
exhibit no long-range order at low temperatures.


title: Mini-review on Monte Carlo programs for Bhabha scattering

abstract:
  We review the status of Monte Carlo generators presently used for simulations
of the large-angle Bhabha process at electron-positron colliders of moderately
high energy (flavour factories), operating at centre-of-mass energies between
about 1 GeV and 10 GeV. It is shown how the theoretical accuracy reached by
present Bhabha programs for physics at flavour factories is at the level of
0.1% and, therefore, comparable with that reached about a decade ago for
luminosity monitoring through small-angle Bhabha scattering at LEP.


title:
Asymmetric and Moving-Frame Approaches to the 2D and 3D Boussinesq
  Equations

abstract:
  Boussinesq systems of nonlinear partial differential equations are
fundamental equations in geophysical fluid dynamics. In this paper, we use
asymmetric ideas and moving frames to solve the two-dimensional Boussinesq
equations with partial viscosity terms studied by Chae ({\it Adv. Math.} {\bf
203} (2006), 497-513) and the three-dimensional stratified rotating Boussinesq
equations studied by Hsia, Ma and Wang ({\it J. Math. Phys.} {\bf 48} (2007),
no. 6, 06560). We obtain new families of explicit exact solutions with multiple
parameter functions. Many of them are the periodic, quasi-periodic, aperiodic
solutions that may have practical significance. By Fourier expansion and some
of our solutions, one can obtain discontinuous solutions. In addition, Lie
point symmetries are used to simplify our arguments.

categories: physics.flu-dyn math-ph math.AP math.MP nlin.SI physics.geo-ph


title: Pushing the precision limit of ground-based eclipse photometry

abstract:
  Until recently, it was considered by many that ground-based photometry could
not reach the high cadence sub-mmag regime because of the presence of the
atmosphere. Indeed, high frequency atmospheric noises (mainly scintillation)
limit the precision that high SNR photometry can reach within small time bins.
If one is ready to damage the sampling of his photometric time-series, binning
the data (or using longer exposures) allows to get better errors, but the
obtained precision will be finally limited by low frequency noises. To observe
several times the same planetary eclipse and to fold the photometry with the
orbital period is thus generally considered as the only option to get very well
sampled and precise eclipse light curve from the ground. Nevertheless, we show
here that reaching the sub-mmag sub-min regime for one eclipse is possible with
a ground-based instrument. This has important implications for transiting
planets characterization, secondary eclipses measurement and small planets
detection from the ground.


title:
Structural Phase Transitions and Vertical Mode Spectra in 2D Finite
  Plasma Crystals

abstract:
  A numerical simulation utilizing a box_tree code is used to investigate the
structure and vertical mode spectrum of finite two-dimensional (2D) plasma
crystals. The overall structural symmetry of the system is examined for various
Debye lengths and a transition from a predominantly hexagonal structure to a
structure having concentric rings along the outer edge and hexagonal lattice
symmetry in the interior is shown to develop as the Debye length increases.
Both the vertical and horizontal oscillation modes for this type of system are
investigated where the horizontal mode spectra is shown to agree with published
results while the vertical mode spectra obtained is shown to agree with an
independent analytical method. The fundamental frequency for the vertical modes
decreases as the mode number l decreases and is shown to have a maximum
corresponding to that which would exist if the system acted in toto as a solid
plane. For low frequency vertical modes, the largest amplitude particle motion
is concentrated within a few inner rings with the outer rings remaining almost
motionless. Both of these are in direct contrast to the data obtained for the
horizontal modes where it is shown that at high frequencies the largest
amplitude particle motion is concentrated within the inner rings.


title:
A full-dimensional quantum dynamical study of the vibrational ground
  state of $H_3O_2^-$ and its isotopomers

abstract:
  We investigated the effect of deuteration on the vibrational ground state of
the hydrated hydroxide anion using a nine-dimensional quantum dynamical model
for the case of J=0. The propagation of the nuclear wave function has been
performed with the multi-configuration time-dependent Hartree method which
yielded zero-point energies for the normal and fully deuterated species in
quantitative agreement with previous diffusion Monte Carlo calculations.
According to the zero-point energy the isotopomers having the hydrogen atom in
the bridging position are more stable by about 1 kJ/mol as compared to the
deuterium case. This holds irrespective of the deuteration state of the two OH
groups. We also report the secondary geometric H/D isotope effect on the O--O
distance which amounts to an elongation of about 0.005 A for the symmetric
isotopomers and 0.009 A in the asymmetric case. Finally, we explore the
isotopomer sensitivity of the ground state tunneling splitting due to the
torsional motion of the two OH groups.


title: Bulk viscosity of superfluid hyperon stars

abstract:
  We calculated bulk viscosity due to non-equilibrium weak processes in
superfluid nucleon-hyperon matter of neutron stars. For that, the dissipative
relativistic hydrodynamics, formulated in paper [1] for superfluid mixtures,
was extended to the case when both nucleons and hyperons are superfluid. It was
demonstrated that in the most general case (when neutrons, protons, Lambda, and
Sigma^{-} hyperons are superfluid), non-equilibrium weak processes generate
sixteen bulk viscosity coefficients, with only three of them being independent.
In addition, we corrected an inaccuracy in a widely used formula for the bulk
viscosity of non-superfluid nucleon-hyperon matter.


title: Diffusive stability of oscillations in reaction-diffusion systems

abstract:
  We study nonlinear stability of spatially homogeneous oscillations in
reaction-diffusion systems. Assuming absence of unstable linear modes and
linear diffusive behavior for the neutral phase, we prove that spatially
localized perturbations decay algebraically with the diffusive rate t^{-n/2} in
space dimension n. We also compute the leading order term in the asymptotic
expansion of the solution, and show that it corresponds to a spatially
localized modulation of the phase. Our approach is based on a normal form
transformation in the kinetics ODE which partially decouples the phase
equation, at the expense of making the whole system quasilinear. Stability is
then obtained by a global fixed point argument in temporally weighted Sobolev
spaces.


title: Constructing arithmetic subgroups of unipotent groups

abstract:
  Let G be a unipotent algebraic subgroup of some GL_m(C) defined over Q. We
describe an algorithm for finding a finite set of generators of the subgroup
G(Z) = G \cap GL_m(Z). This is based on a new proof of the result (in more
general form due to Borel and Harish-Chandra) that such a finite generating set
exists.


title:
Variational calculation of the ppK^- system based on chiral SU(3)
  dynamics

abstract:
  The ppK^- system, as a prototype for possible quasibound Kbar nuclei,is
investigated using a variational approach. Several versions of energy dependent
effective KbarN interactions derived from chiral SU(3) dynamics are employed as
input, together with a realistic NN potential (Av18). Taking into account
theoretical uncertainties in the extrapolations below the KbarN threshold, we
find that the antikaonic dibaryon ppK^- is NOT deeply bound. With the driving
s-wave KbarN interaction the resulting total binding energy is B(ppK^-) = 20
$\pm$ 3 MeV and the mesonic decay width involving KbarN -> \pi Y is expected to
be in the range 40 - 70 MeV. Properties of this quasibound ppK^- system (such
as density distributions of nucleons and antikaon) are discussed. The
\Lambda(1405), as an I=0 quasi-bound state of Kbar and a nucleon, appears to
survive in the ppK^- cluster. Estimates are given for the influence of p-wave
KbarN interactions and for the width from two-nucleon absorption (KbarNN -> YN)
processes. With inclusionof these effects and dispersive corrections from
absorption, the ppK^- binding energy is expected to be in the range 20 - 40
MeV, while the total decay width can reach 100 MeV but with large theoretical
uncertainties.


title: Monte Carlo analysis of CLAS data

abstract:
  We present a fit of the virtual-photon scattering asymmetry of polarized Deep
Inelastic Scattering which combines a Monte Carlo technique with the use of a
redundant parametrization based on Neural Networks. We apply the result to the
analysis of CLAS data on a polarized proton target.


title: Discrete Tracy-Widom Operators

abstract:
  Integrable operators arise in random matrix theory, where they describe the
asymptotic eigenvalue distribution of large self-adjoint random matrices from
the generalized unitary ensembles. This paper considers discrete Tracy-Widom
operators, and gives sufficient conditions for a discrete integrable operator
to be the square of a Hankel matrix. Examples include the discrete Bessel
kernel and kernels arising from the almost Mathieu equation and the Fourier
transform of Mathieu's equation.


title:
Conception et Evaluation de XQuery dans une architecture de m\'ediation
  "Tout-XML"

abstract:
  XML has emerged as the leading language for representing and exchanging data
not only on the Web, but also in general in the enterprise. XQuery is emerging
as the standard query language for XML. Thus, tools are required to mediate
between XML queries and heterogeneous data sources to integrate data in XML.
This paper presents the XMedia mediator, a unique tool for integrating and
querying disparate heterogeneous information as unified XML views. It describes
the mediator architecture and focuses on the unique distributed query
processing technology implemented in this component. Query evaluation is based
on an original XML algebra simply extending classical operators to process
tuples of tree elements. Further, we present a set of performance evaluation on
a relational benchmark, which leads to discuss possible performance
enhancements.


title:
Interpr\'etation vague des contraintes structurelles pour la RI dans des
  corpus de documents XML - \'Evaluation d'une m\'ethode approch\'ee de RI
  structur\'ee

abstract:
  We propose specific data structures designed to the indexing and retrieval of
information elements in heterogeneous XML data bases. The indexing scheme is
well suited to the management of various contextual searches, expressed either
at a structural level or at an information content level. The approximate
search mechanisms are based on a modified Levenshtein editing distance and
information fusion heuristics. The implementation described highlights the
mixing of structured information presented as field/value instances and free
text elements. The retrieval performances of the proposed approach are
evaluated within the INEX 2005 evaluation campaign. The evaluation results rank
the proposed approach among the best evaluated XML IR systems for the VVCAS
task.


title:
Automorphisms and derivations of Borel subalgebras and their nilradicals
  in Kac-Moody algebras

abstract:
  In this paper, we determine derivations of Borel subalgebras and their
derived subalgebras called nilradicals, in Kac-Moody algebras (and
contragredient Lie algebras) over any field of characteristic 0; and we also
determine automorphisms of those subalgebras in symmetrizable Kac-Moody
algebras. The results solve a conjecture posed by R. V. Moody about 30 years
ago which generalizes a result by B. Kostant and which is discussed by A.
Fialowski using Lie algebra cohomology in case of affine type.


title:
Axisymmetric gravitational MHD equilibria in the presence of plasma
  rotation

abstract:
  In this paper, extending the investigation developed in an earlier paper
(Cremaschini et al., 2008), we pose the problem of the kinetic description of
gravitational Hall-MHD equilibria which may arise in accretion disks (AD)
plasmas close to compact objects. When intense EM and gravitational fields,
generated by the central object, are present, a convenient approach can be
achieved in the context of the Vlasov-Maxwell description. In this paper the
investigation is focused primarily on the following two aspects:
  1) the formulation of the kinetic treatment of G-Hall-MHD equilibria. Based
on the identification of the relevant first integrals of motion, we show that
an explicit representation can be given for the equilibrium kinetic
distribution function. For each species this is represented as a superposition
of suitable generalized Maxwellian distributions;
  2) the determination of the constraints to be placed on the fluid fields for
the existence of the kinetic equilibria. In particular, this permits a unique
determination of the functional form of the species number densities and of the
fluid partial pressures, in terms of suitably prescribed flux functions.


title: Teacher Learning of Technology-Enhanced Formative Assessment

abstract:
  Technology-Enhanced Formative Assessment (TEFA) is a pedagogy for teaching
with classroom response technology. Teacher Learning of TEFA is a five-year
research project studying teacher change, in the context of an intensive
professional development program designed to help science and mathematics
teachers learn TEFA. First, we provide an overview of the project's
participating teachers, its intervention (consisting of the technology, the
pedagogy, and the professional development program), and its research design.
Then, we present narratives describing the unfolding change process experienced
by four teachers. Afterward, we present some preliminary findings of the
research, describe a "model for the co-evolution of teacher and pedagogy" that
we are developing, and identify general implications for professional
development.


title:
Ultrafast manipulation of electron spins in a double quantum dot device:
  A real-time view

abstract:
  We consider a double quantum dot system with two embedded and non-aligned
spin impurities to manipulate the magnitude and polarization of the electron
spin density. The device is attached to semi-infinite one-dimensional leads
which are treated exactly. We provide a real-time description of the electron
spin dynamics when a sequence of ultrafast voltage pulses acts on the device.
The numerical simulations are carried out using a spin generalized and modified
version of a recently proposed algorithm for the time propagation of open
systems [Phys. Rev. B {\bf 72}, 035308 (2005)]. Time-dependent spin
accumulations and spin currents are calculated during the entire operating
regime which includes spin injection and read-out processes. The full knowledge
of the electron dynamics allows us to engineer the transient responses and
improve the device performance. An approximate rate equation for the electron
spin is also derived and used to discuss the numerical results.


title:
On electron-positron pair production using a two level on resonant
  multiphoton approximation

abstract:
  We present an indepth investigation of certain aspects of the two level on
resonant multiphoton approximation to pair production from vacuum in the
presence of strong electromagnetic fields. Numerical computations strongly
suggest that a viable experimental verification of this approach using modern
optical laser technology can be achieved. It is shown that use of higher
harmonic within the presently available range of laser intensities can lead to
multiphoton processes offering up to 10^12 pairs per laser shot. Finally the
range of applicability of this approximation is examined from the point of view
of admissible values of electric field strength and energy spectrum of the
created pairs.


title:
Orthopositronium lifetime: analytic results in O(alpha) and O(alpha^3
  ln(alpha))

abstract:
  We present the O(alpha) and O(alpha^3 ln(alpha)) corrections to the total
decay width of orthopositronium in closed analytic form, in terms of basic
transcendental numbers, which can be evaluated numerically to arbitrary
precision.


title:
Crossover Between Organized and Disorganized States In Some
  Non-Equilibrium Systems

abstract:
  We study numerically the crossover between organized and disorganized states
of three non-equilibrium systems: the Poisson/coalesce random walk (PCRW), a
one-dimensional spin system and a quasi one-dimensional lattice gas. In all
cases, we describe this crossover in terms of the average spacing between
particles/domain borders $< S(t) >$ and the spacing distribution functions
$p^{(n)}(s)$. The nature of the crossover is not the same for all systems,
however, we found that for all systems the nearest neighbor distribution
$p^{(0)}(s)$ is well fitted by the Berry-Robnik model. The destruction of the
level repulsion in the crossover between organized an disorganized states is
present in all systems. Additionally, we found that the correlations between
domains in the gas and spin systems are not strong and can be neglected in a
first approximation but for the PCRW the correlations between particles must be
taken into account. To find $p^{(n)}(s)$ with $n>1$, we propose two different
analytical models based on the Berry-Robnik model. Our models give us a good
approximation for the statistical behavior of these systems in their crossover
and allow us to quantify the degree of order/disorder of the system.


title:
Quadratic-Argument Approach to Nonlinear Schrodinger Equation and
  Coupled Ones

abstract:
  The two-dimensional cubic nonlinear Schr\"{o}dinger equation is used to
describe the propagation of an intense laser beam through a medium with Kerr
nonlinearity. The coupled two-dimensional cubic nonlinear Schr\"{o}dinger
equations are used to describe interaction of electromagnetic waves with
different polarizations in nonlinear optics. In this paper, we solve the above
equations by imposing a quadratic condition on the related argument functions
and using their symmetry transformations. More complete families of exact
solutions of such type are obtained. Many known interesting solutions, such
soliton ones, turn out to be special cases of our solutions.

categories: math-ph math.AP math.MP nlin.SI physics.optics


title: The SDSS DR6 Luminosity Functions of Galaxies

abstract:
  We present number counts, luminosity functions (LFs) and luminosity densities
of galaxies obtained using the Sloan Digital Sky Survey Sixth Data Release in
all SDSS photometric bands. Thanks to the SDSS DR6, galaxy statistics have
increased by a factor of ~9 in the u-band and by a factor of ~4-5 in the rest
of the SDSS bands with respect to the previous work of Blanton et al. (2003b).
In addition, we have achieved a high redshift completeness in our galaxy
samples. Firstly, by making use of the survey masks, provided by the NYU-VAGC
DR6, we have been able to define an area on the sky of high angular redshift
completeness. Secondly, we guarantee that brightness-dependent redshift
incompleteness is small within the magnitude ranges that define our galaxy
samples. With these advances, we have estimated very accurate SDSS DR6 LFs in
both the bright and the faint end. In the {0.1}^r-band, our SDSS DR6 luminosity
function is well fitted by a Schechter LF with parameters Phi_{*}=0.90 +/-
0.07$, M_{*}-5log_{10}h=-20.73 +/- 0.04 and alpha=-1.23 +/- 0.02. As compared
with previous results, we find some notable differences. In the bright end of
the {0.1}^u-band luminosity function we find a remarkable excess, of ~1.7 dex
at M_{{0.1}^u}=-20.5, with respect to the best-fit Schechter LF. This excess
weakens in the {0.1}^g-band, fading away towards the very red {0.1}^z-band. A
preliminary analysis on the nature of this bright-end bump reveals that it is
mostly comprised of active galaxies and QSOs. It seems, therefore, that an
important fraction of this exceeding luminosity may come from nuclear activity.
In the faint end of the SDSS DR6 luminosity functions, where we can reach 1-1.5
magnitudes deeper than the previous SDSS LF estimation, we obtain a steeper
slope [ABRIDGED].


title:
Fokker-Planck Kinetic description of small-scale fluid turbulence for
  classical incompressible fluids

abstract:
  Extending the statistical approach proposed in a parallel paper \cite%
{Tessarotto2008-aa}, purpose of this work is to propose a stochastic inverse
kinetic theory for small-scale hydrodynamic turbulence based on the
introduction of a suitable \textit{local phase-space probability density
function} (pdf). In particular, we pose the problem of the construction of
Fokker-Planck kinetic models of hydrodynamic turbulence. The approach here
adopted is based on the so-called IKT approach (inverse kinetic theory),
developed by Ellero et al. (2004-2008) which permits an exact phase-space
description of incompressible fluids based on the adoption of a local pdf. We
intend to show that for prescribed models of stochasticity the present approach
permits to determine uniquely the time evolution of the stochastic fluid
fields. The stochastic-averaged local pdf is shown to obey a kinetic equation
which, although generally non-Markovian, locally in velocity-space can be
approximated by means of a suitable Fokker-planck kinetic equation. As a side
result, the same pdf is proven to have generally a non-Gaussian behavior.


title: Splitting the wavefunctions of two particles in two boxes

abstract:
  I consider two identical quantum particles in two boxes. We can split each
box, and thereby the wavefunction of each particle, into two parts. When two
half boxes are interchanged and combined with the other halves, where do the
two particles end up? I solve this problem for two identical bosons and for two
identical fermions. The solution can be used to define a measurement that
yields some information about the relative phase between the two parts of a
split wavefunction.


title: Peering Into Hadronic Matter: The Electron-Ion Collider

abstract:
  A unique new facility, capable of colliding beams of electrons with a wide
range of nuclei as well as polarized protons and light ions, has been proposed
to study the role of gluons in matter and perform precision mapping of the
structure of nucleons and nuclei. The physics prospects of the proposed
Electron-Ion Collider (EIC) are discussed.


title:
Site Dilution in the Half-Filled One-Band Hubbard Model: Ring Exchange,
  Charge Fluctuations and Application to La2Cu_{1-x}(Mg/Zn)_xO4

abstract:
  We study the ground state quantum spin fluctuations around the N\'eel ordered
state for the one-band ($t,U$) Hubbard model on a site-diluted square lattice.
An effective spin Hamiltonian, $H_{\rm s}^{(4)}$, is generated using the
canonical transformation method, expanding to order $t(t/U)^3$. $H_{\rm
s}^{(4)}$ contains four-spin ring exchange terms as well as second and third
neighbor bilinear spin-spin interactions. Transverse spin fluctuations are
calculated to order $1/S$ using a numerical real space algorithm first
introduced by Walker and Walsteadt. Additional quantum charge fluctuations
appear to this order in $t/U$, coming from electronic hopping and virtual
excitations to doubly occupied sites. The ground state staggered magnetization
on the percolating cluster decreases with site dilution $x$, vanishing very
close to the percolation threshold. We compare our results in the Heisenberg
limit, $t/U \to 0$, with quantum Monte Carlo (QMC) results on the same model
and confirm the existence of a systematic $x$-dependent difference between
$1/S$ and QMC results away from $x=0$. For finite $t/U$, we show that the
effects of both the ring exchange and charge fluctuations die away rapidly with
increasing $t/U$. We use our finite $t/U$ results to make a comparison with
results from experiments on La$_2$Cu$_{1-x}$(Mg/Zn)$_x$O$_4$.


title: Generalization of the Born rule

abstract:
  A new formulation of quantum mechanics is proposed based on a new principle
that can be considered a generalization of the Born rule. The principle is
composed of a mathematical expression and an associated interpretation, and
establishes a correlation between the positions of a particle at two different
times. Under reasonable conditions for the wave function, this correlation
implies that the particles follow quasi-classical trajectories. It is also
shown that the Born rule is equivalent to a particular case of the new
principle. These features allow the principle to provide a unified explanation
of the results of the statistical experiments and of the quasi-classical
macroscopic evolution.
  There is a strong analogy between the new quantum principle and a
probabilistic principle which is necessary to derive empirical predictions from
the mathematical formalism of probability theory. This principle is referred to
by some authors as Cournot's principle, while other authors use the equivalent
notion of typicality. In this paper probability theory and quantum mechanics
are formulated in such a way as to explicitly include the two principles and to
emphasize the very similar conceptual structure of the two theories.


title:
A near-infrared interferometric survey of debris disc stars. II.
  CHARA/FLUOR observations of six early-type dwarfs

abstract:
  High-precision interferometric observations of six early-type main sequence
stars known to harbour cold debris discs have been obtained in the
near-infrared K band with the FLUOR instrument at the CHARA Array. The measured
squared visibilities are compared to the expected visibility of the stellar
photospheres based on theoretical photospheric models taking into account
rotational distortion, searching for potential visibility reduction at short
baselines due to circumstellar emission. Our observations bring to light the
presence of resolved circumstellar emission around one of the six target stars
(zeta Aql) at the 5 sigma level. The morphology of the emission source cannot
be directly constrained because of the sparse spatial frequency sampling of our
interferometric data. Using complementary adaptive optics observations and
radial velocity measurements, we find that the presence of a low-mass companion
is a likely origin for the excess emission. The potential companion has a
K-band contrast of four magnitudes, a most probable mass of about 0.6 Msun, and
is expected to orbit between about 5.5 AU and 8 AU from its host star assuming
a purely circular orbit. Nevertheless, by adjusting a physical debris disc
model to the observed Spectral Energy Distribution of the zeta Aql system, we
also show that the presence of hot dust within 10 AU from zeta Aql, producing a
total thermal emission equal to 1.69 +- 0.31% of the photospheric flux in the K
band, is another viable explanation for the observed near-infrared excess. Our
re-interpretation of archival near- to far-infrared photometric measurements
shows however that cold dust is not present around zeta Aql at the sensitivity
limit of the IRS and MIPS instruments onboard Spitzer, and urges us to remove
zeta Aql from the category of bona fide debris disc stars.


title: Spatially resolving the hot CO around the young Be star 51 Ophiuchi

abstract:
  51 Oph is one of the few young Be stars displaying a strong CO overtone
emission at 2.3 microns in addition to the near infrared excess commonly
observed in this type of stars. In this paper we first aim to locate the CO
bandheads emitting region. Then, we compare its position with respect to the
region emitting the near infrared continuum. We have observed 51 Oph with AMBER
in low spectral resolution (R=35), and in medium spectral resolution (R=1500)
centered on the CO bandheads. The medium resolution AMBER observations clearly
resolve the CO bandheads. Both the CO bandheads and continuum emissions are
spatially resolved by the interferometer. Using simple analytical ring models
to interpret the measured visibilities, we find that the CO bandheads emission
region is compact, located at $0.15_{-0.04}^{0.07}$AU from the star, and that
the adjacent continuum is coming from a region further away
$0.25_{-0.03}^{0.06}$AU. These results confirm the commonly invoked scenario in
which the CO bandheads originate in a dust free hot gaseous disk. Furthermore,
the continuum emitting region is closer to the star than the dust sublimation
radius (by at least a factor two) and we suggest that hot gas inside the dust
sublimation radius significantly contributes to the observed 2 $\mu$m continuum
emission.


title: Observation of negative impulse velocity in free space

abstract:
  Since the 1983 definition of the speed of light in vacuum as a fundamental
constant with the exact value of 299792458 m/s the question remains as to what
apart from the wavefront travels at that speed. It is commonly assumed that the
entire wave-packet or an impulse of the electromagnetic radiation in free space
does. Here it is shown, both theoretically and experimentally, that there
exists a region close to the source, where, while the wave-front travels at the
speed of light, the individual impulses comprising the body of the wave-packet
appear to slow down and even go backwards in time. This three-dimensional
near-field late-time effect may also explain some of the free-space
superluminal measurements.


title:
Matrix factorizations and intertwiners of the fundamental
  representations of quantum group U_q (sl_n)

abstract:
  We want to construct a homological link invariant whose Euler characteristic
is MOY polynomial as Khovanov and Rozansky constructed a categorification of
HOMFLY polynomial. The present paper gives the first step to construct a
categorification of MOY polynomial. For the essential colored planar diagrams
with additional data which is a sequence naturally induced by coloring, we
define matrix factorizations, and then we define a matrix factorization for
planar diagram obtained by gluing the essential colored planar diagrams as
tensor product of the matrix factorizations for the essential planar diagrams.
Moreover, we show that some matrix factorizations deribed from tensor product
of the essential matrix factorizations have homotopy equivalences corresponding
to MOY relations.


title: Superstrings on AdS_4 x CP^3 as a Coset Sigma-model

abstract:
  According to the recent proposal by Aharony, Bergman, Jafferis and Maldacena
the N=6 supersymmetric Chern-Simons theory in three dimensions has a 't Hooft
limit whose holographic dual is described by type IIA superstings on AdS_4 x
CP^3 background. We argue that the Green-Schwarz action for type IIA string
theory on AdS_4 x CP^3 with kappa-symmetry partially fixed can be understood as
a coset sigma-model on the same space supplied with a proper Wess-Zumino term.
We construct the corresponding sigma-model Lagrangian and show that it is
invariant under a local fermionic symmetry which for generic bosonic string
configurations allows one to remove 8 out of 24 fermionic degrees of freedom.
The remaining 16 fermions together with their bosonic partners should describe
the physical content of AdS_4 x CP^3 superstring. As further evidence, we
demonstrate that in the plane-wave limit the quadratic action arising from our
model reproduces the one emerging from the type IIA superstring. The coset
sigma-model is classically integrable which opens up the possibility to
investigate its dynamics in a way very similar to the case of AdS_5 x S^5
superstrings.


title: Tagging photon interactions at the LHC

abstract:
  Photon interactions at the LHC result in striking final states with much
lower hadronic activity in the central detectors than for pp interactions. In
addition, the elastic exchange of a photon leads to a proton scattered at
almost zero-degree angle. Tagging photon interactions relies on either the use
of large rapidity gaps or on the detection of the scattered proton using very
forward detectors. The studies related to such detectors are presented,
including their characterization, their acceptance and reconstruction
performance. Limitations due to the LHC beamline misalignment and possible
solutions are also given.


title:
Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching
  a Puzzle by Exclusive and Kinematically Complete Measurements

abstract:
  The ABC effect - a puzzling low-mass enhancement in the $\pi\pi$ invariant
mass spectrum - is well-known from inclusive measurements of two-pion
production in nuclear fusion reactions. Here we report on first exclusive and
kinematically complete measurements of the most basic double pionic fusion
reaction $pn \to d \pi^0\pi^0$ at 1.03 and 1.35 GeV. The measurements, which
have been carried out at CELSIUS-WASA, reveal the ABC effect to be a
$(\pi\pi)_{I=L=0}$ channel phenomenon associated with both a resonance-like
energy dependence in the integral cross section and the formation of a
$\Delta\Delta$ system in the intermediate state. A corresponding simple
s-channel resonance ansatz provides a surprisingly good description of the
data.


title:
Optical absorption spectra and monomer interaction in polymers.
  Investigation of exciton coupling in DNA hairpins

abstract:
  We investigate the effect of exciton coupling on the optical absorption
spectrum of polymer molecules under conditions of strong inhomogeneous
broadening. We demonstrate that the dependence of the maximum in the rescaled
absorption spectrum on the number of monomers is determined by the average
monomer excitation energies and their resonant coupling and insensitive to the
inhomogeneous broadening. Thus the absorption spectrum can be used to determine
optical interactions between monomers. The results are applied to the
absorption spectra of poly-A poly-T DNA hairpins and used to interpret the
dependence of the absorption spectrum on the number of monomers. We also
discuss exciton localization in these hairpins.


title:
Evidence of a Massive Black Hole Companion in the Massive Eclipsing
  Binary V Puppis

abstract:
  Up to now, most stellar-mass black holes were discovered in X-ray emitting
binaries, in which the black holes are formed through a common-envelope evolu
tion. Here we give evidence for the presence of a massive black hole candidate
as a tertiary companion in the massive eclipsing binary V Puppis. We found that
the orbital period of this short-period binary (P=1.45 days) shows a periodic
variation while it undergoes a long-term increase. The cyclic period
oscillation can be interpreted by the light-travel time effect via the presence
of a third body with a mass no less than 10.4 solar mass. However, no spectral
lines of the third body were discovered indicating that it is a massive black
hole candidate. The black hole candidate may correspond to the weak X-ray
source close to V Puppis discovered by Uhuru, Copernicus, and ROSAT satellites
produced by accreting materials from the massive binary via stellar wind. The
circumstellar matter with many heavy elements around this binary may be formed
by the supernova explosion of the progenitor of the massive black hole. All of
the observations suggest that a massive black hole is orbiting the massive
close binary V Puppis with a period of 5.47 years. Meanwhile, we found the
central close binary is undergoing slow mass transfer from the secondary to the
primary star on a nuclear time scale of the secondary component, revealing that
the system has passed through a rapid mass-transfer stage.


title:
Testing Lorentz Invariance and CPT Conservation with NuMI Neutrinos in
  the MINOS Near Detector

abstract:
  A search for a sidereal modulation in the MINOS near detector neutrino data
was performed. If present, this signature could be a consequence of Lorentz and
CPT violation as predicted by a class of extensions to the Standard Model. No
evidence for a sidereal signal in the data set was found, implying that there
is no significant change in neutrino propagation that depends on the direction
of the neutrino beam in a sun-centered inertial frame. Upper limits on the
magnitudes of the Lorentz and CPT violating terms in these extensions to the
Standard Model lie between 0.01-1% of the maximum expected, assuming a
suppression of these signatures by factor of $10^{-17}$. \


title: Injectives in residuated algebras

abstract:
  Injectives in several classes of structures associated with logic are
characterized. Among the classes considered are residuated lattices,
MTL-algebras, IMTL-algebras, BL-algebras, NM-algebras and bounded hoops.


title: Examples of finite $p$-divisible sets of MHS

abstract:
  We provide some examples which give evidence to the conjectures contained in
my paper "Finiteness of $p$-Divisible Sets of Multiple Harmonic Sums"
(math.NT/0303043). All the main theoretical results can be found in that paper.


abstract:
  We present the Green-Schwarz action for Type IIA strings on $AdS_4\times
CP^3$. The action is based on a $\Zop_4$ automorphism of the coset
$OSp(4|6)/(SO(1,3)\times SU(3)\times U(1))$. The equations of motion admit a
representation in terms of a Lax connection, showing that the system is
classically integrable.


title: Pavelka-style completeness in expansions of \L ukasiewicz logic

abstract:
  An algebraic setting for the validity of Pavelka style completeness for some
natural expansions of \L ukasiewicz logic by new connectives and rational
constants is given. This algebraic approach is based on the fact that the
standard MV-algebra on the real segment $[0, 1]$ is an injective MV-algebra. In
particular the logics associated with MV-algebras with product and with
divisible MV-algebras are considered.


title: U-spin Implication for B_s Physics and New Physics

abstract:
  With U-spin symmetry, b->s and b->d penguin decays could be a subtle probe of
CP violating new physics contributions. We show that, for B->PP (P stands for a
pseudoscalar meson), the U-spin relation is expected to be violated for only
one decay pair by assuming that new physics affects only b->s transition
processes. We also very shortly discuss the polarizations of two types of
U-spin pairs for B->VV (V stands for a vector meson).


title: Heavy quark spectroscopy and prediction of bottom baryon masses

abstract:
  I discuss several recent highly accurate theoretical predictions for masses
of baryons containing the b quark, as well as an effective supersymmetry
between heavy quark baryons and mesons. I also suggest some possibilities for
observing exotic hadrons containing heavy quarks.


title:
Stabilization of Neutral Thin Shells By Gravitational Effects From
  Electric Fields

abstract:
  We study the properties of a system consisting of an uncharged spherically
symmetric two dimensional extended object which encloses a stationary point
charge placed in the shell's center. We show that there can be a static and
stable configuration for the neutral shell, using only the gravitational field
of the charged source as a stabilizing mechanism. In particular, two types of
shells are studied: a dust shell and a string gas shell. The dynamical
possibilities are also analyzed, including the possibility of child universe
creation.


title: The gravitational wave burst signal from core collapse of rotating stars

abstract:
  We present results from detailed general relativistic simulations of stellar
core collapse to a proto-neutron star, using two different microphysical
nonzero-temperature nuclear equations of state as well as an approximate
description of deleptonization during the collapse phase. Investigating a wide
variety of rotation rates and profiles as well as masses of the progenitor
stars and both equations of state, we confirm in this very general setup the
recent finding that a generic gravitational wave burst signal is associated
with core bounce, already known as type I in the literature. The previously
suggested type II (or "multiple-bounce") waveform morphology does not occur.
Despite this reduction to a single waveform type, we demonstrate that it is
still possible to constrain the progenitor and postbounce rotation based on a
combination of the maximum signal amplitude and the peak frequency of the
emitted gravitational wave burst. Our models include to sufficient accuracy the
currently known necessary physics for the collapse and bounce phase of
core-collapse supernovae, yielding accurate and reliable gravitational wave
signal templates for gravitational wave data analysis. In addition, we assess
the possiblity of nonaxisymmetric instabilities in rotating nascent
proto-neutron stars. We find strong evidence that in an iron core-collapse
event the postbounce core cannot reach sufficiently rapid rotation to become
subject to a classical bar-mode instability. However, many of our postbounce
core models exhibit sufficiently rapid and differential rotation to become
subject to the recently discovered dynamical instability at low rotation rates.


title: Encoding Subsystem Codes

abstract:
  In this paper we investigate the encoding of operator quantum error
correcting codes i.e. subsystem codes. We show that encoding of subsystem codes
can be reduced to encoding of a related stabilizer code making it possible to
use all the known results on encoding of stabilizer codes. Along the way we
also show how Clifford codes can be encoded. We also show that gauge qubits can
be exploited to reduce the encoding complexity.


title: Hot-electron noise suppression in n-Si via the Hall effect

abstract:
  We investigate how hot-electron fluctuations in n-type Si are affected by the
presence of an intense (static) magnetic field in a Hall geometry. By using the
Monte Carlo method, we find that the known Hall-effect-induced redistribution
of electrons among valleys can suppress electron fluctuations with a
simultaneous enhancement of the drift velocity.


title: Game Refinement Relations and Metrics

abstract:
  We consider two-player games played over finite state spaces for an infinite
number of rounds. At each state, the players simultaneously choose moves; the
moves determine a successor state. It is often advantageous for players to
choose probability distributions over moves, rather than single moves. Given a
goal, for example, reach a target state, the question of winning is thus a
probabilistic one: what is the maximal probability of winning from a given
state?
  On these game structures, two fundamental notions are those of equivalences
and metrics. Given a set of winning conditions, two states are equivalent if
the players can win the same games with the same probability from both states.
Metrics provide a bound on the difference in the probabilities of winning
across states, capturing a quantitative notion of state similarity.
  We introduce equivalences and metrics for two-player game structures, and we
show that they characterize the difference in probability of winning games
whose goals are expressed in the quantitative mu-calculus. The quantitative
mu-calculus can express a large set of goals, including reachability, safety,
and omega-regular properties. Thus, we claim that our relations and metrics
provide the canonical extensions to games, of the classical notion of
bisimulation for transition systems. We develop our results both for
equivalences and metrics, which generalize bisimulation, and for asymmetrical
versions, which generalize simulation.


title: Leading SU(3) breaking in lightcone distribution amplitudes

abstract:
  The lightcone formalism including SU(3) breaking effects for the light
pseudoscalar mesons is studied using soft-collinear effective theory (SCET),
where the conformal symmetries needed for the expansion can be clearly
implemented. The lightcone distribution amplitudes (LCDAs) are well-defined at
each order in the SCET power counting, lambda. Relations between the LCDAs are
reproduced using the SCET formalism. Treating the SU(3) breaking
perturbatively, the leading breaking effects can be described in a simple
manner. As a result, a new relationship among the LCDAs for the light mesons
pi, K, and eta is developed, valid to leading order in the SU(3) breaking.


title:
Deterministic Designs with Deterministic Guarantees: Toeplitz Compressed
  Sensing Matrices, Sequence Designs and System Identification

abstract:
  In this paper we present a new family of discrete sequences having "random
like" uniformly decaying auto-correlation properties. The new class of infinite
length sequences are higher order chirps constructed using irrational numbers.
Exploiting results from the theory of continued fractions and diophantine
approximations, we show that the class of sequences so formed has the property
that the worst-case auto-correlation coefficients for every finite length
sequence decays at a polynomial rate. These sequences display doppler immunity
as well. We also show that Toeplitz matrices formed from such sequences satisfy
restricted-isometry-property (RIP), a concept that has played a central role
recently in Compressed Sensing applications. Compressed sensing has
conventionally dealt with sensing matrices with arbitrary components.
Nevertheless, such arbitrary sensing matrices are not appropriate for linear
system identification and one must employ Toeplitz structured sensing matrices.
Linear system identification plays a central role in a wide variety of
applications such as channel estimation for multipath wireless systems as well
as control system applications. Toeplitz matrices are also desirable on account
of their filtering structure, which allows for fast implementation together
with reduced storage requirements.


title:
The SU(2) x SU(2) sector in the string dual of N=6 superconformal
  Chern-Simons theory

abstract:
  We examine the string dual of the recently constructed $\mathcal{N}=6$
superconformal Chern-Simons theory of Aharony, Bergman, Jafferis and Maldacena
(ABJM theory). We focus in particular on the $SU(2)\times SU(2)$ sector. We
find a sigma-model limit in which the resulting sigma-model is two
Landau-Lifshitz models added together. We consider a Penrose limit for which we
can approach the $SU(2)\times SU(2)$ sector. Finally, we find a new Giant
Magnon solution in the $SU(2)\times SU(2)$ sector corresponding to one magnon
in each $SU(2)$. We put these results together to find the full magnon
dispersion relation and we compare this to recently found results for ABJM
theory at weak coupling.


title: Ample D4-D2-D0 Decay

abstract:
  We study the wall-crossing behavior of the index of BPS states for D4-D2-D0
brane systems on a Calabi-Yau 3-fold at large radius and point out that not
only is the ``BPS index at large radius'' chamber-dependent, but that the
changes in the index can be large in the sense that they dominate
single-centered black hole entropy. We discuss implications for the weak
coupling OSV conjecture. We also analyze the near horizon limit of
multicentered solutions, introduced in arXiv:0802.2257, for these particular
configurations and comment on a general criterion, conjectured in
arXiv:0802.2257, which identifies those multicentered solutions whose near
horizon limit corresponds to a geometry with a single asymptotic AdS_3 x S^2
boundary.


title:
Spectral signatures of the Fulde-Ferrell-Larkin-Ovchinnikov order
  parameter in one-dimensional optical lattices

abstract:
  We address an imbalanced two-component atomic Fermi gas restricted by a
one-dimensional (1D) optical lattice and an external harmonic potential, within
the mean-field Bogoliubov-de Gennes (BdG) formalism. We show that
characteristic features of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state
are visible in the RF-spectra and in the momentum resolved photoemission
spectra of the gas. Specially, Andreev states or mid-gap states can be clearly
resolved, which gives a direct experimentally observable signature of the
oscillating order parameter.


title:
Social Network Reciprocity as a Phase Transition in Evolutionary
  Cooperation

abstract:
  In Evolutionary Dynamics the understanding of cooperative phenomena in
natural and social systems has been the subject of intense research during
decades. We focus attention here on the so-called "Lattice Reciprocity"
mechanisms that enhance evolutionary survival of the cooperative phenotype in
the Prisoner's Dilemma game when the population of darwinian replicators
interact through a fixed network of social contacts. Exact results on a "Dipole
Model" are presented, along with a mean-field analysis as well as results from
extensive numerical Monte Carlo simulations. The theoretical framework used is
that of standard Statistical Mechanics of macroscopic systems, but with no
energy considerations. We illustrate the power of this perspective on social
modeling, by consistently interpreting the onset of lattice reciprocity as a
thermodynamical phase transition that, moreover, cannot be captured by a purely
mean-field approach.


title: Modulation Field Induces Universe Rotation

abstract:
  In this paper, we consider a time dependent module field on spacetime
extension without modifying commutative relation on noncommutative quantum
plane. The significant idea is that $Lorentz$ symmetry is conserved in module
and unmodule coordinate. We focus on the redefinition of spacetime structure
without considering noncommutative bosonic gas in deforming the product between
fields. Which the null vector is a vector on orthogonal $D$ dimensional
$Hilbert$ spacetime. In $Riemann$ geometry, the equation of motion is deformed
from an induced rotation. Particle field survives on the state composed by two
theoretical assumed $null$ vectors, one is commutative, another is
anticommutative. In the point of view, neutrino and photon mass are produced by
its shift, the rotated effect generates a horizon in redefining particle field.


title:
Sublattice model of atomic scale pairing inhomogeneity in a
  superconductor

abstract:
  We study a toy model for a superconductor on a bipartite lattice, where
intrinsic pairing inhomogeneity is produced by two different coupling constants
on the sublattices. The simplicity of the model allows for analytic solutions
and tests of the consequences of atomic-scale variations in pairing
interactions which have been considered recently in the cuprates. We present
results for the transition temperature, density of states, and thermodynamics
of the system over a phase diagram in the plane of two pairing coupling
constants. For coupling constants of alternating sign, a gapless
superconducting state is stable. Inhomogeneity is generally found to enhance
the critical temperature, and at the same time the superfluid density is
remarkably robust: at T=0, it is suppressed only in the gapless phase.


title:
On the boundary of the moduli spaces of log Hodge structures: triviality
  of the torsor

abstract:
  In this paper we will study the moduli spaces of log Hodge structures
introduced by Kato-Usui. This moduli space is a partial compactification of a
discrete quotient of a period domain. We treat the following 2 cases: (A) the
case where the period domain is Hermitian symmetric, (B) the case where the
Hodge structures are of the mirror quintic type. Especially we study a property
of the torsor.


title: Bounds for solution of linear diophantine equations

abstract:
  Given linear diophantine equation Ax=b, rank A=m. Let d be the maximum of
absolute values of the mxm minors of the matrix (A | b). It is shown that if
M={x : Ax=b, x nonnegative and integer} is nonempty, then there exists
x=(x1,...,xn) in M, such that xi does not exceed d (i=1,2,..,n).


title: On Galois representations and Hilbert-Siegel modular forms

abstract:
  In this paper, we associate Galois representations to globally generic
cuspidal automorphic representations on GSp(4), over a totally real field F,
which are Steinberg at some finite place. This association is compatible with
the local Langlands correspondence for GSp(4) studied recently in a preprint of
Gan and Takeda. As a corollary, we relate the rank of the monodromy operator at
p to the dimensions of the parahoric fixed spaces at p. The Galois
representations are constructed by first passing to GL(4) over a CM extension,
then applying the book of Harris-Taylor plus a refinement due to
Taylor-Yoshida, and finally descending to F by a delicate patching argument.
This is a variation of the techniques used by Blasius and Rogawski in order to
attach motives to Hilbert modular forms.


title: Discovery of a [WO] central star in the planetary nebula Th 2-A

abstract:
  % context About 2500 planetary nebulae are known in our Galaxy but only 224
have central stars with reported spectral types in the Strasbourg-ESO Catalogue
of Galactic Planetary Nebulae (Acker et al. 1992; Acker et al. 1996) % aims We
have started an observational program aiming to increase the number of PN
central stars with spectral classification. % methods By means of spectroscopy
and high resolution imaging, we identify the position and true nature of the
central star. We carried out low resolution spectroscopic observations at
CASLEO telescope, complemented with medium resolution spectroscopy performed at
Gemini South and Magellan telescopes. % results As a first outcome of this
survey, we present for the first time the spectra of the central star of the PN
Th 2-A. These spectra show emission lines of ionized C and O, typical in
Wolf-Rayet stars. % conclusions We identify the position of that central star,
which is not the brightest one of the visual central pair. We classify it as of
type [WO 3]pec, which is consistent with the high excitation and dynamical age
of the nebula.


title:
Polarization Studies: testing explanations of the B -> phi K* puzzle and
  B -> V T decays

abstract:
  It has been observed in B->phiK* and B^{0(+)}->rho^{0(+)}K^{*0} that the
fraction of transverse decays, fT, and the fraction of longitudinal decays, fL,
are roughly equal, in opposition to the naive expectation, fT/fL << 1. If one
requires a single explanation of all polarization puzzles, two possibilities
remain within the standard model (SM): penguin annihilation and rescattering.
We examine the predictions of these two explanations for fT/fL in b -> d
decays. We also study polarization observables in B -> V T decays (V is a
vector and T is a tensor meson) to probe whether the two SM explanations
account for the fT/fL ratio in this type of decays and to further investigate
the two new-physics scenarios which explain the data in B -> pi K and the
phi(rho) K* polarization measurements.


title: The Temperature of Interstellar Clouds from Turbulent Heating

abstract:
  To evaluate the effect of turbulent heating in the thermal balance of
interstellar clouds, we develop an extension of the log-Poisson intermittency
model to supersonic turbulence. The model depends on a parameter, d,
interpreted as the dimension of the most dissipative structures. By comparing
the model with the probability distribution of the turbulent dissipation rate
in a simulation of supersonic and super-Alfvenic turbulence, we find a best-fit
value of d=1.64. We apply this intermittency model to the computation of the
mass-weighted probability distribution of the gas temperature of molecular
clouds, high-mass star-forming cores, and cold diffuse HI clouds. Our main
results are: i) The mean gas temperature in molecular clouds can be explained
as the effect of turbulent heating alone, while cosmic ray heating may dominate
only in regions where the turbulent heating is low; ii) The mean gas
temperature in high-mass star-forming cores with typical FWHM of ~6 km/s
(corresponding to a 1D rms velocity of 2.5 km/s) may be completely controlled
by turbulent heating, which predicts a mean value of approximately 36 K, two to
three times larger than the mean gas temperature in the absence of turbulent
heating; iii) The intermittency of the turbulent heating can generate enough
hot regions in cold diffuse HI clouds to explain the observed CH+ abundance, if
the rms velocity on a scale of 1 pc is at least 3 km/s, in agreement with
previous results based on incompressible turbulence. Because of its importance
in the thermal balance of molecular clouds and high-mass star-forming cores,
the process of turbulent heating may be central in setting the characteristic
stellar mass and in regulating molecular chemical reactions.


title: Reheating in Chaotic D-Term Inflation

abstract:
  A simple model is discussed to give rise to successful reheating in chaotic
D-term inflation with a quadratic inflaton potential, introducing a trilinear
coupling in the K\"ahler potential. Leptogenesis through the inflaton decay is
also discussed in this model.


title:
Study of the Detonation Phase in the Gravitationally Confined Detonation
  Model of Type Ia Supernovae

abstract:
  We study the gravitationally confined detonation (GCD) model of Type Ia
supernovae through the detonation phase and into homologous expansion. In the
GCD model, a detonation is triggered by the surface flow due to single point,
off-center flame ignition in carbon-oxygen white dwarfs. The simulations are
unique in terms of the degree to which non-idealized physics is used to treat
the reactive flow, including weak reaction rates and a time dependent treatment
of material in nuclear statistical equilibrium (NSE). Careful attention is paid
to accurately calculating the final composition of material which is burned to
NSE and frozen out in the rapid expansion following the passage of a detonation
wave over the high density core of the white dwarf; and an efficient method for
nucleosynthesis post-processing is developed which obviates the need for costly
network calculations along tracer particle thermodynamic trajectories.
Observational diagnostics are presented for the explosion models, including
abundance stratifications and integrated yields. We find that for all of the
ignition conditions studied here, a self regulating process comprised of
neutronization and stellar expansion results in final \iso{Ni}{56} masses of
$\sim$1.1\msun. But, more energetic models result in larger total NSE and
stable Fe peak yields. The total yield of intermediate mass elements is
$\sim0.1$\msun and the explosion energies are all around 1.5$\times10^{51}$
ergs. The explosion models are briefly compared to the inferred properties of
recent Type Ia supernova observations. The potential for surface detonation
models to produce lower luminosity (lower \iso{Ni}{56} mass) supernovae is
discussed.


title: Weakly almost periodic functionals on the measure algebra

abstract:
  It is shown that the collection of weakly almost periodic functionals on the
convolution algebra of a commutative Hopf von Neumann algebra is a
C$^*$-algebra. This implies that the weakly almost periodic functionals on
$M(G)$, the measure algebra of a locally compact group $G$, is a
C$^*$-subalgebra of $M(G)^* = C_0(G)^{**}$. The proof builds upon a
factorisation result, due to Young and Kaiser, for weakly compact module maps.
The main technique is to adapt some of the theory of corepresentations to the
setting of general reflexive Banach spaces.


title: Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot

abstract:
  The longitudinal and transverse beam coupling impedance of the first final
TOTEM Roman Pot unit has been measured in the laboratory with the wire method.
For the evaluation of transverse impedance the wire position has been kept
constant, and the insertions of the RP were moved asymmetrically. With the
original configuration of the RP, resonances with fairly high Q values were
observed. In order to mitigate this problem, RF-absorbing ferrite plates were
mounted in appropriate locations. As a result, all resonances were sufficiently
damped to meet the stringent LHC beam coupling impedance requirements.


title: Growth of intersection numbers for free group automorphisms

abstract:
  For a fully irreducible automorphism \phi of the free group F_k we compute
the asymptotics of the intersection number n \mapsto i(T,T'\phi^n) for trees
T,T' in Outer space. We also obtain qualitative information about the geometry
of the Guirardel core for the trees T and T'\phi^n for n large.


title: Geometry of configuration spaces of tensegrities

abstract:
  Consider a graph G with n vertices. In this paper we study geometric
conditions for an n-tuple of points in R^d to admit a tensegrity with
underlying graph G. We introduce and investigate a natural stratification,
depending on G, of the configuration space of all n-tuples in R^d. In
particular we find surgeries on graphs that give relations between different
strata. Based on numerous examples we give a description of geometric
conditions defining the strata for plane tensegrities, we conjecture that the
list of such conditions is sufficient to describe any stratum. We conclude the
paper with particular examples of strata for tensegrities in the plane with a
small number of vertices.


title: N=5,6 Superconformal Chern-Simons Theories and M2-branes on Orbifolds

abstract:
  We explore further our recent generalization of the $\mathcal{N}=4$
superconformal Chern-Simons theories of Gaiotto and Witten. We find and
construct explicitly theories of enhanced $\mathcal{N}=5$ or 6 supersymmetry,
especially $\mathcal{N}=5$, $Sp(2M)\times O(N)$ and $\mathcal{N}=6$,
$Sp(2M)\times O(2)$ theories. The $U(M)\times U(N)$ theory coincides with the
$\mathcal{N}=6$ theory of Aharony, Bergman, Jafferis and Maldacena (ABJM). We
argue that the $\mathcal{N}=5$ theory with $Sp(2N)\times O(2N)$ gauge group can
be understood as an orientifolding of the ABJM model with $U(2N)\times U(2N)$
gauge group. We briefly discuss the Type IIB brane construction of the
$\mathcal{N}=5$ theory and the geometry of the M-theory orbifold.


title: Band-Selective Filter in a Zigzag Graphene Nanoribbon

abstract:
  Electric transport of a zigzag graphene nanoribbon through a step-like
potential or a barrier potential is investigated by using the recursive Green's
function method. In the case of the step-like potential, we demonstrate
numerically that scattering processes obey a selection rule for the band
indices when the number of zigzag chains is even; the electrons belonging to
the ``even'' (``odd'') bands are scattered only into the even (odd) bands so
that the parity of wavefunctions is preserved. The so-called valley-valve
effect can be explained by this selection rule. In the case of the barrier
potential, by tuning the barrier height to be an appropriate value, we show
that it can work as the ``band-selective filter'', which transmits electrons
selectively with respect to the indices of the bands to which the incident
electrons belong. Finally, we suggest that this selection rule can be observed
in the conductance by applying two barrier potentials.


title: Bounds on Codes Based on Graph Theory

abstract:
  Let $A_q(n,d)$ be the maximum order (maximum number of codewords) of a
$q$-ary code of length $n$ and Hamming distance at least $d$. And let
$A(n,d,w)$ that of a binary code of constant weight $w$. Building on results
from algebraic graph theory and Erd\H{o}s-ko-Rado like theorems in extremal
combinatorics, we show how several known bounds on $A_q(n,d)$ and $A(n,d,w)$
can be easily obtained in a single framework. For instance, both the Hamming
and Singleton bounds can derived as an application of a property relating the
clique number and the independence number of vertex transitive graphs. Using
the same techniques, we also derive some new bounds and present some additional
applications.


title: Collective vortex phases in periodic plus random pinning potential

abstract:
  We study theoretically the simultaneous effect of a regular and a random
pinning potentials on the vortex lattice structure at filling factor of 1. This
structure is determined by a competition between the square symmetry of regular
pinning array, by the intervortex interaction favoring a triangular symmetry,
and by the randomness trying to depin vortices from their regular positions.
Both analytical and molecular-dynamics approaches are used. We construct a
phase diagram of the system in the plane of regular and random pinning
strengths and determine typical vortex lattice defects appearing in the system
due to the disorder. We find that the total disordering of the vortex lattice
can occur either in one step or in two steps. For instance, in the limit of
weak pinning, a square lattice of pinned vortices is destroyed in two steps.
First, elastic chains of depinned vortices appear in the film; but the vortex
lattice as a whole remains still pinned by the underlying square array of
regular pinning sites. These chains are composed into fractal-like structures.
In a second step, domains of totally depinned vortices are generated and the
vortex lattice depins from regular array.


title: The Colours of Satellite Galaxies in Groups and Clusters

abstract:
  Current models of galaxy formation predict satellite galaxies in groups and
clusters that are redder than observed. We investigate the effect on the
colours of satellite galaxies produced by the ram pressure stripping of their
hot gaseous atmospheres as the satellites orbit within their parent halo. We
incorporate a model of the stripping process based on detailed hydrodynamic
simulations within the Durham semi-analytic model of galaxy formation. The
simulations show that the environment in groups and clusters is less aggressive
than previously assumed. The main uncertainty in the model is the treatment of
gas expelled by supernovae. With reasonable assumptions for the stripping of
this material, we find that satellite galaxies are able to retain a significant
fraction of their hot gas for several Gigayears, thereby replenishing their
reservoirs of cold, star forming gas and remaining blue for a relatively long
period of time. A bimodal distribution of galaxy colours, similar to that
observed in SDSS data, is established and the colours of the satellite galaxies
are in good agreement with the data. In addition, our model naturally accounts
for the observed dependence of satellite colours on environment, from small
groups to high mass clusters.


title: Superfluidity near phase separation in Bose-Fermi mixtures

abstract:
  We study the transition to fermion pair superfluidity in a mixture of
interacting bosonic and fermionic atoms. The fermion interaction induced by the
bosons and the dynamical screening of the condensate phonons due to fermions
are included using the nonperturbative Hamiltonian flow equations. We determine
the bosonic spectrum near the transition towards phase separation and find that
the superfluid transition temperature may be increased substantially due to
phonon damping.


title: A Glimpse into the Past: The Recent Evolution of Globular Clusters

abstract:
  We present the serendipitous discovery of 195 extragalactic globular clusters
(GCs) in one of the deepest optical images ever obtained, a 126 orbit HST/ACS
imaging study of the nearby Galactic GC NGC 6397. The distant GCs are all found
surrounding a bright elliptical galaxy in the field, and are among the faintest
objects detected in the image, with magnitudes 26 < F814W < 30. We measure the
redshift of the parent elliptical galaxy, using GMOS on Gemini South, to be z =
0.089 (375 Mpc). This galaxy, and its associated clusters, therefore ranks as
one of the most distant such systems discovered to date. The measured light
from these clusters was emitted 1.2 Gyr ago (the lookback time) and therefore
the optical properties hold clues for understanding the evolution of GCs over
the past Gyr. We measure the color function of the bright GCs and find that
both a blue and red population exist, and that the colors of each
sub-population are redder than GCs in local elliptical galaxies of comparable
luminosity. For the blue clusters, the observed color difference from z = 0.089
to today is only slightly larger than predictions from stellar evolution (e.g.,
changes in the luminosity and color of the main-sequence turnoff and the
morphology of the horizontal branch). A larger color difference is found in the
red clusters, possibly suggesting that they are very metal-rich and/or
significantly younger than 12 Gyr.


title: Bounding scalar operator dimensions in 4D CFT

abstract:
  In an arbitrary unitary 4D CFT we consider a scalar operator \phi, and the
operator \phi^2 defined as the lowest dimension scalar which appears in the OPE
\phi\times\phi with a nonzero coefficient. Using general considerations of OPE,
conformal block decomposition, and crossing symmetry, we derive a
theory-independent inequality [\phi^2] \leq f([\phi]) for the dimensions of
these two operators. The function f(d) entering this bound is computed
numerically. For d->1 we have f(d)=2+O(\sqrt{d-1}), which shows that the free
theory limit is approached continuously. We perform some checks of our bound.
We find that the bound is satisfied by all weakly coupled 4D conformal fixed
points that we are able to construct. The Wilson-Fischer fixed points violate
the bound by a constant O(1) factor, which must be due to the subtleties of
extrapolating to 4-\epsilon dimensions. We use our method to derive an
analogous bound in 2D, and check that the Minimal Models satisfy the bound,
with the Ising model nearly-saturating it. Derivation of an analogous bound in
3D is currently not feasible because the explicit conformal blocks are not
known in odd dimensions. We also discuss the main phenomenological motivation
for studying this set of questions: constructing models of dynamical
ElectroWeak Symmetry Breaking without flavor problems.


title:
Strongly spin-polarized current generated in Zeeman-split unconventional
  superconductors

abstract:
  We consider a thin-film normal metal/superconductor junction in the presence
of an externally applied in-plane magnetic field for several symmetries of the
superconducting order parameter. For p-wave superconductors, a strongly
spin-polarized current emerges due to an interplay between the nodal structure
of the superconducting order parameter, the existence or non-existence of
zero-energy surface states, and the Zeeman-splitting of the bands which form
superconductivity. Thus, the polarization depends strongly on the orbital
symmetry of the superconducting state. Our findings suggest a mechanism for
obtaining fully spin-polarized currents crucially involving zero-energy surface
states, not present in s-wave superconductors.


title: Transit Detection of Radial Velocity Planets

abstract:
  The orbital parameters of extra-solar planets have a significant impact on
the probability that the planet will transit the host star. This was recently
demonstrated by the transit detection of HD 17156b whose favourable
eccentricity and argument of periastron dramatically increased its transit
likelihood. We present a study which provides a quantitative analysis of how
these two orbital parameters effect the geometric transit probability as a
function of period. Further, we apply these results to known radial velocity
planets and show that there are unexpectedly high transit probabilities for
planets at relatively long periods. For a photometric monitoring campaign which
aims to determine if the planet indeed transits, we calculate the significance
of a null result and the subsequent constraints that may be applied to orbital
parameters.


title: Finding Large Clique Minors is Hard

abstract:
  We prove that it is NP-complete, given a graph G and a parameter h, to
determine whether G contains a complete graph K_h as a minor.