title: Shake-induced order in nanosphere systems

abstract:
  Self-assembled patterns obtained from a drying nanosphere suspension are
investigated by computer simulations and simple experiments. Motivated by the
earlier experimental results of Sasaki and Hane and Schope, we confirm that
more ordered triangular lattice structures can be obtained whenever a moderate
intensity random shaking is applied on the drying system. Computer simulations
are realized on an improved version of a recently elaborated
Burridge-Knopoff-type model. Experiments are made following the setup of Sasaki
and Hane, using ultrasonic radiation as source for controlled shaking.


title: Exploiting the width difference in B_s -> phi gamma

abstract:
  The photon polarization in B -> V gamma is a sensitive probe of right-handed
currents. In the time dependent decay rate of B_s -> phi gamma the coefficients
S and H in front of the sin(Delta m_s t) and the sinh(Delta Gamma_s /2 t) terms
are sensitive to those right-handed currents. As compared to the B_d system
there is a sizable width difference in B_s mesons which leads to the additional
measurable observable H. We show with a Monte Carlo simulation that the
expected resolution on S and H will be about 0.15 at the LHCb experiment for
Delta Gamma_s/Gamma_s = 0.15 and a data sample of 2 fb^{-1}. We also show that
the observable H can be measured from the untagged decay rate of B_s mesons
which has considerable experimental advantages as no flavour tag will be
required. The resolution on H is inversely proportional to the B_s width
difference Delta Gamma_s. These experimental prospects have to be compared with
the Standard Model predictions S_{phi gamma} = 0 \pm 0.002 and H_{phi \gamma} =
0.047 \pm 0.025+0.015 presented in this paper. We also give the Standard Model
prediction and the experimental sensitivity for the direct CP asymmetry in B_s
-> phi gamma.


title: The shapes of galaxies in the Sloan Digital Sky Survey

abstract:
  We determine the underlying shapes of spiral and elliptical galaxies in the
Sloan Digital Sky Survey Data Release 6 from the observed distribution of
projected galaxy shapes, taking into account the effects of dust extinction and
reddening. We assume that the underlying shapes of spirals and ellipticals are
well approximated by triaxial ellipsoids. The elliptical galaxy data are
consistent with oblate spheroids, with a correlation between luminosity and
ellipticity: the mean values of minor to middle axis ratios are 0.41+-0.03 for
Mr ~ -18 ellipticals, and 0.76+-0.04 for Mr ~-22.5 ellipticals. Ellipticals
show almost no dependence of axial ratio on galaxy colour, implying a
negligible dust optical depth.
  There is a strong variation of spiral galaxy shapes with colour indicating
the presence of dust. The intrinsic shapes of spiral galaxies in the SDSS-DR6
are consistent with flat disks with a mean and dispersion of thickness to
diameter ratio of (21+-2)%, and a face-on ellipticity, e, of ln(e)=-2.33+-0.79.
Not including the effects of dust in the model leads to disks that are
systematically rounder by up to 60%. More luminous spiral galaxies tend to have
thicker and rounder disks than lower-luminosity spirals. Both elliptical and
spiral galaxies tend to be rounder for larger galaxies.
  The marginalised value of the edge-on r-band dust extinction E_0 in spiral
galaxies is E_0 ~ 0.45 magnitudes for galaxies of median colours, increasing to
E_0=1 magnitudes for g-r>0.9 and E_0=1.9 for the luminous and most compact
galaxies, with half-light radii <2kpc/h.


title: Jumping numbers of hyperplane arrangements

abstract:
  M. Saito recently proved that the jumping numbers of a hyperplane arrangement
depend only on the combinatorics of the arrangement. However, a formula in
terms of the combinatorial data was still missing. In this note, we give a
formula and a different proof of the fact that the jumping numbers of a
hyperplane arrangement depend only on the combinatorics. We also give a
combinatorial formula for part of the Hodge spectrum and for the inner jumping
multiplicities.


title:
Kinemetry of SINS High-Redshift Star-Forming Galaxies: Distinguishing
  Rotating Disks from Major Mergers

abstract:
  We present a simple set of kinematic criteria that can distinguish between
galaxies dominated by ordered rotational motion and those involved in major
merger events. Our criteria are based on the dynamics of the warm ionized gas
(as traced by H-alpha) within galaxies, making this analysis accessible to
high-redshift systems, whose kinematics are primarily traceable through
emission features. Using the method of kinemetry (developed by Krajnovic and
co-workers), we quantify asymmetries in both the velocity and velocity
dispersion maps of the warm gas, and the resulting criteria enable us to
empirically differentiate between non-merging and merging systems at high
redshift. We apply these criteria to 11 of our best-studied rest-frame
UV/optical-selected z~2 galaxies for which we have near infrared integral field
spectroscopic data from SINFONI on the VLT. Of these 11 systems, we find that
>50% have kinematics consistent with a single rotating disk interpretation,
while the remaining systems are more likely undergoing major mergers. This
result, combined with the short formation timescales of these systems, provides
evidence that rapid, smooth accretion of gas plays a significant role in galaxy
formation at high redshift.


title: Entanglement Entropy in Loop Quantum Gravity

abstract:
  The entanglement entropy between quantum fields inside and outside a black
hole horizon is a promising candidate for the microscopic origin of black hole
entropy. We show that the entanglement entropy may be defined in loop quantum
gravity, and compute its value for spin network states. The entanglement
entropy for an arbitrary region of space is expressed as a sum over punctures
where the spin network intersects the region's boundary. Our result agrees
asymptotically with results previously obtained from the isolated horizon
framework, and we give a justification for this agreement. We conclude by
proposing a new method for studying corrections to the area law and its
implications for quantum corrections to the gravitational action.


title:
Deep Analyses of Nulling in Arecibo Pulsars Reveal Further Periodic
  Behavior

abstract:
  Sensitive Arecibo observations provide an unprecedented ability to detect
nulls for an accurate pulse-modulation quelling (PMQ) analysis. We demonstrate
that a number of conal pulsars show "periodic nulling" similar to the
phenomenon found earlier in pulsar B1133+16.


title:
Field and current distributions and ac losses in a bifilar stack of
  superconducting strips

abstract:
  In this paper I first analytically calculate the magnetic-field and
sheet-current distributions generated in an infinite stack of thin
superconducting strips of thickness d, width 2a >> d, and arbitrary separation
D when adjacent strips carry net current of magnitude I in opposite directions.
Each strip is assumed to have uniform critical current density Jc, critical
sheet-current density Kc = Jc d, and critical current Ic = 2a Kc, and the
distribution of the current density within each strip is assumed to obey
critical-state theory. I then derive expressions for the ac losses due to
magnetic-flux penetration both from the strip edges and from the top and bottom
of each strip, and I express the results in terms of integrals involving the
perpendicular and parallel components of the magnetic field. After numerically
evaluating the ac losses for typical dimensions, I present analytic expressions
from which the losses can be estimated.


title: Residually free 3-manifolds

abstract:
  We classify those compact 3-manifolds with incompressible toral boundary
whose fundamental groups are residually free. For example, if such a manifold
$M$ is prime and orientable and the fundamental group of $M$ is non-trivial
then $M \cong \Sigma\times S^1$, where $\Sigma$ is a surface.


title: On the geography of threefolds of general type

abstract:
  Let $X$ be a complex nonsingular projective 3-fold of general type. We show
that there are positive constants $c$, $c'$ and $m_1$ such that $\chi (\omega
_X)\geq -c\Vol (X)$ and $P_m(X)\geq c'm^3\Vol (X)$ for all $m\geq m_1$.


title: Amplified Dispersive Optical Tomography

abstract:
  Optical coherence tomography (OCT) has proven to be a powerful technique for
studying tissue morphology in ophthalmology, cardiology, and endomicroscopy.
Its performance is limited by the fundamental trade-off between the imaging
sensitivity and acquisition speed -- a predicament common in virtually all
imaging systems. In this paper, we circumvent this limit by using distributed
Raman post-amplification of the reflection from the sample. We combine the
amplification with simultaneously performed dispersive Fourier transformation,
a process that maps the optical spectrum into an easily measured time-domain
waveform. The Raman amplification enables measurement of weak signals which are
otherwise buried in noise. It extends the depth range without sacrificing the
acquisition speed or causing damage to the sample. As proof of concept,
single-shot imaging with 15 dB improvement in sensitivity at an axial scan rate
of 36.6 MHz is demonstrated.


title: Hamiltonian Quantum Cellular Automata in 1D

abstract:
  We construct a simple translationally invariant, nearest-neighbor Hamiltonian
on a chain of 10-dimensional qudits that makes it possible to realize universal
quantum computing without any external control during the computational
process. We only require the ability to prepare an initial computational basis
state which encodes both the quantum circuit and its input. The computational
process is then carried out by the autonomous Hamiltonian time evolution. After
a time polynomially long in the size of the quantum circuit has passed, the
result of the computation is obtained with high probability by measuring a few
qudits in the computational basis. This result also implies that there cannot
exist efficient classical simulation methods for generic translationally
invariant nearest-neighbor Hamiltonians on qudit chains, unless quantum
computers can be efficiently simulated by classical computers (or, put in
complexity theoretic terms, unless BPP=BQP).


title: Neutrinos from Auger Sources

abstract:
  The Pierre Auger observatory has presented evidence that the arrival
directions of cosmic rays with energies in excess of 6x10^7 TeV may be
correlated with nearby active galactic nuclei (AGN). In this context we revisit
a suggestion based on gamma ray observations that nearby Fanaroff-Riley I
galaxies such as Cen A and M87 are the sources of the local cosmic rays. We
compute the accompanying neutrino flux and find a flux within reach of
second-generation kilometer-scale neutrino telescopes.


title:
New Measurements of Fine-Scale CMB Polarization Power Spectra from
  CAPMAP at Both 40 and 90 GHz

abstract:
  We present new measurements of the cosmic microwave background (CMB)
polarization from the final season of the Cosmic Anisotropy Polarization MAPper
(CAPMAP). The data set was obtained in winter 2004-2005 with the 7 m antenna in
Crawford Hill, New Jersey, from 12 W-band (84-100 GHz) and 4 Q-band (36-45 GHz)
correlation polarimeters with 3.3' and 6.5' beamsizes, respectively. After
selection criteria were applied, 956 (939) hours of data survived for analysis
of W-band (Q-band) data. Two independent and complementary pipelines produced
results in excellent agreement with each other. A broad suite of null tests as
well as extensive simulations showed that systematic errors were minimal, and a
comparison of the W-band and Q-band sky maps revealed no contamination from
galactic foregrounds. We report the E-mode and B-mode power spectra in 7 bands
in the range 200 < l < 3000, extending the range of previous measurements to
higher l. The E-mode spectrum, which is detected at 11 sigma significance, is
in agreement with cosmological predictions and with previous work at other
frequencies and angular resolutions. The BB power spectrum provides one of the
best limits to date on B-mode power at 4.8 uK^2 (95% confidence).


title: The totally nonnegative part of G/P is a CW complex

abstract:
  The totally nonnegative part of a partial flag variety G/P has been shown by
the first author to be a union of semi-algebraic cells. Moreover she showed
that the closure of a cell is the union of smaller cells. In this note we
provide glueing maps for each of the cells to prove that the totally
nonnegative part of G/P is a CW complex. This generalizes a result of
Postnikov, Speyer and the second author for Grassmannians.


title: Closed ideals in some algebras of analytic functions

abstract:
  We obtain a complete description of closed ideals of the algebra
$\mathcal{D}\cap \mathrm{lip}_\alpha},$ $0<\alpha\leq{1/2},$ where
$\mathcal{D}$ is the Dirichlet space and $\mathrm{lip}_\alpha}$ is the algebra
of analytic functions satisfying the Lipschitz condition of order $\alpha.$


title: Higher representations on the lattice: perturbative studies

abstract:
  We present analytical results to guide numerical simulations with Wilson
fermions in higher representations of the colour group. The ratio of $\Lambda$
parameters, the additive renormalization of the fermion mass, and the
renormalization of fermion bilinears are computed in perturbation theory,
including cactus resummation. We recall the chiral Lagrangian for the different
patterns of symmetry breaking that can take place with fermions in higher
representations, and discuss the possibility of an Aoki phase as the fermion
mass is reduced at finite lattice spacing.


title: Closed ideals in analytic weighted Lipschitz algebras

abstract:
  We obtain a complete description of closed ideals in weighted Lipschitz
algebras $\Lambda_\omega$ of analytic functions on the unit disk satisfying the
following condition $$\frac{|f(z)-f(w)|}{\omega(|z-w|)}=o(1)\qquad(as |z-w|
\longrightarrow 0),$$ where $\omega$ is a modulus of continuity satisfying some
regularity conditions.


title: On the Luminosity and Mass Loss of Galactic AGB Stars

abstract:
  As part of a reanalysis of Galactic Asymptotic Giant Branch stars (hereafter
AGB stars) at infrared wavelengths, we discuss here two samples (the first of
carbon-rich stars, the second of S stars) for which photometry in the near- and
mid-IR and distance estimates are available. Whenever possible we searched also
for mass-loss rates. The observed spectral energy distributions extended in all
cases up to 20 $\mu$m and for the best-observed sources up to 45 $\mu$m. The
wide wavelength coverage allows us to obtain reliable bolometric corrections,
and hence bolometric magnitudes. We show that mid-IR fluxes are crucial for
estimating bolometric magnitudes for stars with dusty envelopes and that the
so-called luminosity problem of C stars (i.e. the suggestion that they are less
luminous than predicted by models) does not appear to exist.


title: Generation Symmetry and E_6 Unification

abstract:
  The group E_6 for grand unification is combined with the generation symmetry
group SO(3)_g. The coupling matrices in the Yukawa interaction are identified
with the vacuum expectation values of scalar fields which are representations
of the generation symmetry. These values determine the hierarchy of the
fermions as well as their mixings and CP-violation. This generation mixing
appears in conjunction with the mixing of the standard model fermions with the
heavy fermions present in the lowest representation of E_6. A close connection
between charged and neutral fermions is observed relating for instance the CKM
mixings with the mass splittings of the light neutrinos. Numerical fits with
only few parameters reproduce quantitatively all known fermion properties. The
model predicts an inverted neutrino hierarchy and gives rather strict values
for the light and heavy neutrino masses as well as for the 0\nu 2\beta decay
parameter. It also predicts that the masses of the two lightest of six `right
handed' neutrinos lie in the low TeV region.


title: Review of "Garden of integrals"

abstract: This is a review of the book "Garden of integrals" by Frank Burk.


title: Topology change in causal quantum gravity

abstract:
  The role of topology change in a fundamental theory of quantum gravity is
still a matter of debate. However, when regarding string theory as
two-dimensional quantum gravity, topological fluctuations are essential. Here
we present a third quantization of two-dimensional surfaces based on the method
of causal dynamical triangulation (CDT). Formally, our construction is similar
to the c = 0 non-critical string field theory developed by Ishibashi, Kawai and
others, but physically it is quite distinct. Unlike in non-critical string
theory the topology change of spatial slices is well controlled and regulated
by Newton's constant.


title: Final-state Polarization in Bs Decays

abstract:
  Certain Bs --> V_1V_2 decays (V_i is a vector meson) can be related by flavor
SU(3) symmetry to corresponding Bd --> V_3V_4 decays. In this paper, we show
that the final-state polarization can be predicted in the Bs decay, assuming
polarization measurements of the Bd decay. This can be done within the scenario
of penguin annihilation (PA), which has been suggested as an explanation of the
unexpectedly large transverse polarization in B-->phi K^*. PA is used to
estimate the breaking of flavor SU(3) symmetry in pairs of decays. Two of these
for which PA makes a reasonably precise prediction of the size of SU(3)
breaking are (Bs --> phiphi, Bd --> phi K^{0*}) and (Bs --> phi {\bar K}^{0*},
Bd --> {\bar K}^{0*} K^{0*}). The polarization measurement in the Bd decay can
be used to predict the transverse polarization in the Bs decay, and will allow
a testing of PA.


title: Ideaux fermes d'algebres de Beurling analytiques sur le bidisque

abstract:
  We study the closed ideal in the Beurling algebras
$\mathcal{A}^{+}_{\alpha,\beta}$ of holomorphic function $f$ in the bidisc such
that $\sum_{n,m\geq 0}|\hat{f}(n,m)|(1+n)^{\alpha}(1+m)^\beta<+\infty$. We
determine the function $f\in\mathcal{A}^{+}_{\alpha,\beta}$ such that the
ideals generated by $f$ coincide with the ideal generated by their zeros set.


title:
Phase-transient hierarchical turbulence as an energy correlation
  generator of blazar light curves

abstract:
  Hierarchical turbulent structure constituting a jet is considered to
reproduce energy-dependent variability in blazars, particularly, the
correlation between X- and gamma-ray light curves measured in the TeV blazar
Markarian 421. The scale-invariant filaments are featured by the ordered
magnetic fields that involve hydromagnetic fluctuations serving as electron
scatterers for diffusive shock acceleration, and the spatial size scales are
identified with the local maximum electron energies, which are reflected in the
synchrotron spectral energy distribution (SED) above the near-infrared/optical
break. The structural transition of filaments is found to be responsible for
the observed change of spectral hysteresis.


title: Heating and Acceleration of Intracluster Medium Electrons by Turbulence

abstract:
  In this paper we investigate the feasibility of bremsstrahlung radiation from
`nonthermal' electrons as a source of hard X-rays from the intracluster medium
of clusters of galaxies. With an exact treatment of the Coulomb collisions in a
Fokker-Planck analysis of the electron distribution we find that the severe
difficulties with lifetimes of `nonthermal' particles found earlier by
Petrosian (2001) using a cold target model remain problematic. We then address
possible acceleration of background electrons into a nonthermal tail. We assume
a simplified but generic acceleration rate and determine the expected evolution
of an initially Maxwellian distribution of electrons. We find that strong
nonthermal components arise only for rapid rate of acceleration which also
heats up the entire plasma. These results confirm the conclusion that if the
observed `nonthermal' excesses are due to some process accelerating the
background thermal electrons this process must be short lived.


title:
Mesoscopic competition of superconductivity and ferromagnetism:
  conductance peak statistics in metallic grains

abstract:
  We investigate the competition between superconductivity and ferromagnetism
in chaotic ultra-small metallic grains in a regime where both phases can
coexist. We use an effective Hamiltonian that combines a BCS-like pairing term
and a ferromagnetic Stoner-like spin exchange term. We study the transport
properties of the grain in the Coulomb blockade regime and identify signatures
of the coexistence between pairing and exchange correlations in the mesoscopic
fluctuations of the conductance peak spacings and peak heights.


title: Jet enhanced accretion growth of supermassive black holes

abstract:
  We investigate the effect of a disc-driven jet on the accretion growth of
cosmological supermassive black holes (SMBHs). The presence of a jet enhances
the mass growth rate because for a given luminosity, the mass accretion rate,
is higher (or equivalently, the radiative efficiency e_r is lower for a fixed
mass accretion rate) than that predicted by standard accretion disc theory. As
jets carry away very little of the accreting matter, a larger proportion of the
rest mass can reach the black hole during episodes of jet activity. We show
quantitatively that the conditions required to grow a rapidly spinning black
hole to a mass ~ 10^9 solar masses by redshift z ~ 6, whilst satisfying the
observational constraint e_r > 0.1, are considerably less restrictive for
jet-enhanced disc accretion than for standard disc accretion, which requires
implausibly high super-Eddington accretion rates. Furthermore, jet-enhanced
accretion growth offers a viable explanation for the observed correlation
between black hole mass and radio-loudness of quasars.


title: High-fidelity gates in a Josephson qubit

abstract:
  We demonstrate new experimental procedures for measuring small errors in a
superconducting quantum bit (qubit). By carefully separating out gate and
measurement errors, we construct a complete error budget and demonstrate single
qubit gate fidelities of 0.98, limited by energy relaxation. We also introduce
a new metrology tool -- a Ramsey interference error filter -- that can measure
the occupation probability of the state $\ket{2}$ down to $10^{-4}$, a
magnitude near the fault tolerant threshold.


title:
t'- and t"-dependence of the bulk-limit superconducting condensation
  energy of the 2D Hubbard model

abstract:
  The 2D Hubbard model having the 2nd- and 3rd-neighbor transfer energies t'
and t" is investigated by use of the variational Monte Carlo method. At the
nearly optimal doping with on-site Coulomb energy U=6 (energy unit is t) the
condensation energy Econd for the d-wave superconductivity (SC) is computed for
lattices of sizes from 10x10 to 28x28 with the aim to get its bulk-limit value.
t" is fixed at -t'/2. Outside and in the neighborhood of the SDW region of
-0.16=<t'=<-0.08 the SC Econd dominates over the SDW Econd. At t'=-0.05 and
-0.10 we obtained a definitely finite bulk-limit SC Econd of the order of the
experimental value for YBCO. At t'=0 Econd nearly vanishes. For t'=<-0.18, the
SC Econd strongly oscillates as a function of the lattice size, when periodic
boundary conditions (b.c.'s) are imposed to both axes. In the case of periodic
and antiperiodic b.c.'s, a finite bulk-limit value is obtained at t'=-0.22.
Econd tends to vanish with further decrease of t'. With our results the SC of
LSCO is understandable with t'~ -0.10. The t' values of Hg1201, Tl2201 and
Na-CCOC seem close to -0.20 so that they locate in the boundary zone of SC
indicated in the present work. Slightly larger U improves the situation by
increasing Econd.


title: Instanton Solution of a Nonlinear Potential in Finite Size

abstract:
  The Euclidean path integral method is applied to a quantum tunneling model
which accounts for finite size ($L$) effects. The general solution of the Euler
Lagrange equation for the double well potential is found in terms of Jacobi
elliptic functions. The antiperiodic instanton interpolates between the
potential minima at any finite $L$ inside the quantum regime and generalizes
the well known (anti)kink solution of the infinite size case. The derivation of
the functional determinant, stemming from the quantum fluctuation contribution,
is given in detail. The explicit formula for the finite size semiclassical path
integral is presented.


title:
Observational Possibility of the "Snow Line" on the Surface of
  Circumstellar Disks with the Scattered Light

abstract:
  We discuss how we obtain the spatial distribution of ice on the surface of
the circumstellar disk around young stars. Ice in the disks plays a very
important role in various issues, for instance, on the disk structure, on the
planet formation, on the isotopic anomaly in meteorites, and on the origin of
the sea on the Earth. Therefore, the spatially resolved observation of the
condensation/sublimation front of ice, so-called ``snow line'' is strongly
required. Here, we propose a new method for obtaining the spatially resolved
``snow line'' on the circumstellar disks by observing 3 \micron H$_2$O ice
feature in the scattered light. Based on radiative transfer considerations, we
show that the feature is clearly imprinted in the spectrum of the scattered
light from both optically thick and thin circumstellar disks. We also show that
the scattered light and the H$_2$O ice feature from protoplanetary disks are
detectable and spatially resolvable with the current instruments through a
$H_2O$ narrowband filter around 3 \micron. Finally, we present a diagnostics of
disk dust properties on the $K-H_2O$ and $K-L'$ two color diagram.


title: Zonal Velocity Bands and the Solar Activity Cycle

abstract:
  We compare the zonal flow pattern in subsurface layers of the Sun with the
distribution of surface magnetic features like sunspots and polar faculae. We
demonstrate that in the activity belt, the butterfly pattern of sunspots
coincides with the fast stream of zonal flows, although part of the sunspot
distribution does spill over to the slow stream. At high latitudes, the polar
faculae and zonal flow bands have similar distributions in the spatial and
temporal domains.


title:
Higher Order Terms of Kerr Parameter for Blandford-Znajek Monopole
  Solution

abstract:
  Blandford-Znajek mechanism, by which the rotational energy of a black hole is
extracted through electromagnetic fields, is one of the promising candidates as
an essential process of the central engine of active compact objects such as
Gamma-Ray Bursts. The only known analytical solution of this mechanism is the
perturbative monopole solution for Kerr parameter a up to the second order
terms. In order to apply Blandford-Znajek mechanism to rapidly rotating black
holes, we try to obtain the perturbation solution up to the fourth order. As a
result, we find that the fourth order terms of the vector potential diverge at
infinity, which implies that the perturbation approach breaks down at large
distance from the black hole. Although there are some uncertainties about the
solution due to the unknown boundary condition at infinity for the fourth order
terms, we can derive the evaluation of the total energy flux extracted from the
black hole up to fourth order of a without any ambiguity. Further more, from
the comparison between the numerical solution that is valid for 0<a<1 and the
fourth order solution, we find that the fourth order solution reproduces the
numerical result better than the second order solution. At the same time, since
the fourth order solution does not match well with numerical result at large a,
we conclude that more higher order terms are required to reproduce the
numerical result.


title:
Magnetic and Transport Properties of a Coupled Hubbard Bilayer with
  Electron and Hole Doping

abstract:
  The single band, two dimensional Hubbard Hamiltonian has been extensively
studied as a model for high temperature superconductivity. While Quantum Monte
Carlo simulations within the dynamic cluster approximation are now providing
considerable evidence for a d-wave superconducting state at low temperature,
such a transition remains well out of reach of finite lattice simulations
because of the "sign problem". We show here that a bilayer Hubbard model, in
which one layer is electron doped and one layer is hole doped, can be studied
to lower temperatures and exhibits an interesting signal of d-wave pairing. The
results of our simulations bear resemblance to a recent report on the magnetic
and superconducting properties of Ba$_2$Ca$_3$Cu$_4$O$_8$F$_2$ which contains
both electron and hole doped CuO$_2$ planes. We also explore the phase diagram
of bilayer models in which each sheet is at half-filling.


title:
Cascade and Damping of Alfv\'{e}n-Cyclotron Fluctuations: Application to
  Solar Wind Turbulence Spectrum

abstract:
  With the diffusion approximation, we study the cascade and damping of
Alfv\'{e}n-cyclotron fluctuations in solar plasmas numerically. Motivated by
wave-wave couplings and nonlinear effects, we test several forms of the
diffusion tensor. For a general locally anisotropic and inhomogeneous diffusion
tensor in the wave vector space, the turbulence spectrum in the inertial range
can be fitted with power-laws with the power-law index varying with the wave
propagation direction. For several locally isotropic but inhomogeneous
diffusion coefficients, the steady-state turbulence spectra are nearly
isotropic in the absence of damping and can be fitted by a single power-law
function. However, the energy flux is strongly polarized due to the
inhomogeneity that leads to an anisotropic cascade. Including the anisotropic
thermal damping, the turbulence spectrum cuts off at the wave numbers, where
the damping rates become comparable to the cascade rates. The combined
anisotropic effects of cascade and damping make this cutoff wave number
dependent on the wave propagation direction, and the propagation direction
integrated turbulence spectrum resembles a broken power-law, which cuts off at
the maximum of the cutoff wave numbers or the $^4$He cyclotron frequency.
Taking into account the Doppler effects, the model can naturally reproduce the
broken power-law wave spectra observed in the solar wind and predicts that a
higher break frequency is aways accompanied with a greater spectral index
change that may be caused by the increase of the Alfv\'{e}n Mach number, the
reciprocal of the plasma beta, and/or the angle between the solar wind velocity
and the mean magnetic field. These predictions can be tested by future
observations.


title: Shimura curves of genus at most two

abstract:
  In this article, we enumerate all Shimura curves X^D_0(N) of genus at most
two.


title: Symmetry constraints on phonon dispersion in graphene

abstract:
  Taking into account the constraints imposed by the lattice symmetry, we
calculate the phonon dispersion for graphene with interactions between the
first, second, and third nearest neighbors in the framework of the Born--von
Karman model. Analytical expressions obtained for the dispersion of the
out-of-plane (bending) modes give the nonzero sound velocity. The dispersion of
four in-plane modes is determined by coupled equations. Values of the force
constants are found in fitting with frequencies at critical points and with
elastic constants measured on graphite.


title: Natural line shape

abstract:
  The observable line shape of the spontaneous emission depends on the
procedure of atom's excitation. The spectrum of radiation emitted by a
two-level atom excited from the ground state by a pi pulse of the resonant pump
field is calculated for the case when the Rabi frequency is much larger than
the relaxation rate. It is shown that the central part of the spectral
distribution has a standard Lorentzian form, whereas for detunings from the
resonance that are larger than the Rabi frequency the spectral density falls
off faster. The shape of the wings of the spectral line is sensitive to the
form of the pi pulse. The implications for the quantum Zeno effect theory and
for the estimates of the duration of quantum jumps are discussed.


title: Shrinkage Effect in Ancestral Maximum Likelihood

abstract:
  Ancestral maximum likelihood (AML) is a method that simultaneously
reconstructs a phylogenetic tree and ancestral sequences from extant data
(sequences at the leaves). The tree and ancestral sequences maximize the
probability of observing the given data under a Markov model of sequence
evolution, in which branch lengths are also optimized but constrained to take
the same value on any edge across all sequence sites. AML differs from the more
usual form of maximum likelihood (ML) in phylogenetics because ML averages over
all possible ancestral sequences. ML has long been known to be statistically
consistent -- that is, it converges on the correct tree with probability
approaching 1 as the sequence length grows. However, the statistical
consistency of AML has not been formally determined, despite informal remarks
in a literature that dates back 20 years. In this short note we prove a general
result that implies that AML is statistically inconsistent. In particular we
show that AML can `shrink' short edges in a tree, resulting in a tree that has
no internal resolution as the sequence length grows. Our results apply to any
number of taxa.


title:
Distribution of an Ohmic current in the close vicinity of a quantum
  point contact

abstract:
  We present the essential findings of the screening theory of the integer
quantum Hall effect (IQHE) considering a quantum point contact (QPC). Our
approach is to solve the Poisson and the Schroedinger equations
self-consistently, taking into account electron interactions, within a Hartree
type approximation for a two dimensional electron gas (2DEG) subject to high
perpendicular magnetic fields. The Coulomb interaction between the electrons
separates 2DEG into two co-existing regions, namely quasi-metallic compressible
and quasi-insulating incompressible regions, which exhibit peculiar screening
and transport properties. In the presence of an external current, we show that
this current is confined into the incompressible regions where the drift
velocity is finite. In particular, we investigate the distribution of these
incompressible strips and their relation with the quantum Hall plateaus
considering a quasi 1D constriction, i.e. a QPC.


title: Measuring Flavor Mixing with Minimal Flavor Violation at the LHC

abstract:
  The mixing between third and second (or first) generation squarks is very
small in supersymmetric models with minimal flavor violation such as gauge-,
anomaly- or gaugino-mediation. An opportunity to measure this mixing will arise
if the lightest stop is close enough in mass to the lightest neutralino, so
that the decays into third generation quarks are kinematically forbidden. We
analyze under which circumstances it might become possible to measure at the
Large Hadron Collider (LHC) the rate of the flavor changing stop decays.


title: Gravitational Instability of Shocked Interstellar Gas Layers

abstract:
  In this paper we investigate gravitational instability of shocked gas layers
using linear analysis. An unperturbed state is a self-gravitating isothermal
layer which grows with time by the accretion of gas through shock fronts due to
a cloud-cloud collision. Since the unperturbed state is not static, and cannot
be described by a self-similar solution, we numerically solved the perturbation
equations and directly integrated them over time. We took account of the
distribution of physical quantities across the thickness. Linearized
Rankine-Hugoniot relations were imposed at shock fronts as boundary conditions.
The following results are found from our unsteady linear analysis: the
perturbation initially evolves in oscillatory mode, and begins to grow at a
certain epoch. The wavenumber of the fastest growing mode is given by
$k=2\sqrt{2\pi G\rho_\mathrm{E} {\cal M\mit}}/c_\mathrm{s}$, where
$\rho_\mathrm{E}, c_\mathrm{s}$ and $\cal M\mit$ are the density of parent
clouds, the sound velocity and the Mach number of the collision velocity,
respectively. For this mode, the transition epoch from oscillatory to growing
mode is given by $t_g = 1.2/\sqrt{2\pi G\rho_\mathrm{E} {\cal M\mit}}$. The
epoch at which the fastest growing mode becomes non-linear is given by
$2.4\delta_0^{-0.1}/\sqrt{2\pi G \rho_\mathrm{E}{\cal M\mit}}$, where
$\delta_0$ is the initial amplitude of the perturbation of the column density.
As an application of our linear analysis, we investigate criteria for
collision-induced fragmentation. Collision-induced fragmentation will occur
only when parent clouds are cold, or $\alpha_0=5c_\mathrm{s}^2 R/2G M < 1$,
where $R$ and $M$ are the radius and the mass of parent clouds, respectively.


title: The Pauli principle revisited

abstract:
  By the Pauli exclusion principle no quantum state can be occupied by more
than one electron. One can put it as a constraint on the electron density
matrix that bounds its eigenvalues by 1. Shortly after its discovery the Pauli
principle has been replaced by skew symmetry of a multi-electron wave function.
  In this paper we solve a longstanding problem about the impact of this
replacement on the electron density matrix, that goes far beyond the original
Pauli principle.


title: Finiteness results for flat surfaces: large cusps and short geodesics

abstract:
  For fixed g and T we show that finiteness of the set of affine equivalence
classes of flat surfaces of genus g whose Veech groups contain a cusp of
hyperbolic co-area less than T. We obtain new restrictions on Veech groups: we
show that any non-elementary Veech group can appear only finitely many times in
a fixed stratum, that any non-elementary Veech group is of finite index in its
normalizer, and that the quotient of the upper half plane by a non-lattice
Veech group contains arbitrarily large embedded disks. These are proved using
the finiteness of the set of affine equivalence classes of flat surfaces of
genus g whose Veech group contains a hyperbolic element with eigenvalue less
than T.


title: Fermi Surface Effect on Lorenz Number of Correlated Metal

abstract:
  We investigate an effect that an ideal Lorenz number $L_{\rm i}$ of
correlated metal shows peculiar Fermi surface dependence, which is caused by
the onset of a particular channel of Umklapp scattering. We evaluate $L_{\rm
i}$ for some simple models and transition metals, and note that $L_{\rm i}$ for
Na$_x$CoO$_2$ decreases sensitively as $x$ approaches an Umklapp threshold
around $x_c \simeq 0.6$.


title: Non-Hermitian spectral effects in a PT-symmetric waveguide

abstract:
  We present a numerical study of the spectrum of the Laplacian in an unbounded
strip with PT-symmetric boundary conditions. We focus on non-Hermitian features
of the model reflected in an unusual dependence of the eigenvalues below the
continuous spectrum on various boundary-coupling parameters.


title:
Interpolation of Sobolev spaces, Littlewood-Paley inequalities and Riesz
  transforms on graphs

abstract:
  Let $\Gamma$ be a graph endowed with a reversible Markov kernel $p$, and $P$
the associated operator, defined by $Pf(x)=\sum_y p(x,y)f(y)$. Denote by
$\nabla$ the discrete gradient. We give necessary and/or sufficient conditions
on $\Gamma$ in order to compare $\Vert \nabla f \Vert_{p}$ and $\Vert
(I-P)^{1/2}f \Vert_{p}$ uniformly in $f$ for $1<p<+\infty$. These conditions
are different for $p<2$ and $p>2$. The proofs rely on recent techniques
developed to handle operators beyond the class of Calder\'on-Zygmund operators.
For our purpose, we also prove Littlewood-Paley inequalities and interpolation
results for Sobolev spaces in this context, which are of independent interest.


title:
Analysis of squeal noise and mode coupling instabilities including
  damping and gyroscopic effects

abstract:
  This paper deals with an audible disturbance known as automotive clutch
squeal noise from the viewpoint of friction-induced mode coupling instability.
Firstly, an auto-coupling model is presented showing a non-conservative
circulatory effect originating from friction forces. Secondly, the stability of
an equilibrium is investigated by determining the eigenvalues of the system
linearized equations. The effects of the circulatory and gyroscopic actions are
examined analytically and numerically to determine their influence on the
stability region. Separate and combined effects are analysed with and without
structural damping and important information is obtained on the role of each
parameter and their interactions regarding overall stability. Not only is
structural damping shown to be of primary importance, as reported in many
previous works, this article also highlights a particular relationship with
gyroscopic effects. A method of optimizing both the stability range and its
robustness with respect to uncertainty on system parameters is discussed after
which practical design recommendations are given.


title:
Quasielastic neutron scattering of hydrated BaZr_{0.90}A_{0.10}O_{2.95}
  (A = Y and Sc)

abstract:
  Proton motions in hydrated proton conducting perovskites
BaZr_{0.90}A_{0.10}O_{2.95} (A = Y and Sc) have been investigated using
quasielastic neutron scattering. The results reveal a localized motion on the
ps time scale and with an activation energy of ~10-30 meV, in both materials.
The temperature dependence of the total mean square displacement of the protons
suggests an onset of this motion at a temperature of about 300 K. Comparison of
the QENS results to density functional theory calculations suggests that for
both materials this motion can be ascribed to intra-octahedral proton transfers
occurring close to a dopant atom. The low activation energy, more than ten
times lower than the activation energy for the macroscopic proton conductivity,
suggests that this motion is not the rate-limiting process for the long-range
proton diffusion, i.e. it is not linked to the two materials significantly
different proton conductivities.


title: Regularity and non-emptyness of linear systems in $\mathbb P^n$

abstract:
  The main goal of this paper is to present a new algorithm bounding the
regularity and ``alpha'' (the lowest degree of existing hypersurface) of a
linear system of hypersurfaces (in $\mathbb P^n$) passing through multiple
points in general position. To do the above we formulate and prove new theorem,
which allows to show non-specialty of linear system by splitting it into
non-special (and simpler) systems. As a result we give new bounds for multiple
point Seshadri constants on $\PP^2$.


title:
Continuous local time of a purely atomic immigration superprocess with
  dependent spatial motion

abstract:
  A purely atomic immigration superprocess with dependent spatial motion in the
space of tempered measures is constructed as the unique strong solution of a
stochastic integral equation driven by Poisson processes based on the excursion
law of a Feller branching diffusion, which generalizes the work of Dawson and
Li (2003). As an application of the stochastic equation, it is proved that the
superprocess possesses a local time which is Holder continuous of order
$\alpha$ for every $\alpha< 1/2$. We establish two scaling limit theorems for
the immigration superprocess, from which we derive scaling limits for the
corresponding local time.


title: Planetesimal and gas dynamics in binaries

abstract:
  Observations of extrasolar planets reveal that planets can be found in close
binary systems, where the semi-major axis of the binary orbit is less than 20
AU. The existence of these planets challenges planet formation theory, because
the strong gravitational perturbations due to the companion increase encounter
velocities between planetesimals and make it difficult for them to grow through
accreting collisions. We study planetesimal encounter velocities in binary
systems, where the planetesimals are embedded in a circumprimary gas disc that
is allowed to evolve under influence of the gravitational perturbations of the
companion star. We find that the encounter velocities between planetesimals of
different size strongly depend on the gas disc eccentricity. In all cases
studied, inclusion of the full gas dynamics increases the encounter velocity
compared to the case of a static, circular gas disc. Full numerical parameter
exploration is still impossible, but we derive analytical formulae to estimate
encounter velocities between bodies of different sizes given the gas disc
eccentricity. The gas dynamical evolution of a protoplanetary disc in a binary
system tends to make planetesimal accretion even more difficult than in a
static, axisymmetric gas disc.


title:
Discovery of heavily-obscured AGN among 7 INTEGRAL hard X-ray sources
  observed by Chandra

abstract:
  We observed 7 INTEGRAL sources with the Chandra X-ray Observatory to refine
their localization to ~2 arcsec and to study their X-ray spectra. Two sources
are inferred to have a Galactic origin: IGR J08390-4833 is most likely a
magnetic cataclysmic variable with a white dwarf spin period ~1,450 s; and IGR
J21343+4738 is a high-mass X-ray binary. Five sources (IGR J02466-4222, IGR
J09522-6231, IGR J14493-5534, IGR J14561-3738, and IGR J23523+5844) prove to be
AGN with significant intrinsic X-ray absorption along the line of sight. Their
redshifts and hard X-ray (17-60 keV) luminosities range from 0.025 to 0.25 and
from ~2x10^43 to ~2x10^45 erg/s, respectively, with the distance to IGR
J14493-5534 remaining unknown. The sources IGR J02466-4222 and IGR J14561-3738
are likely Compton-thick AGN with absorption column densities NH>10^24 cm^-2,
and the former further appears to be one of the nearest X-ray bright,
optically-normal galaxies. With the newly-identified sources, the number of
heavily-obscured (NH>10^24 cm^-2) AGN detected by INTEGRAL has increased to
~10. Therefore, such objects constitute 10-15% of hard X-ray bright, non-blazar
AGN in the local Universe. The small ratio (<<1%) of soft (0.5-8.0 keV) to hard
(17-60 keV) band fluxes (Chandra to INTEGRAL) and the non-detection of optical
narrow-line emission in some of the Compton-thick AGN in our sample suggests
that there is a new class of objects in which the central massive black hole
may be surrounded by a geometrically-thick dusty torus with a narrow ionization
cone.


title: Pseudospin, supersymmetry and the shell structure of atomic nuclei

abstract:
  The evolution of single-particle energies with varying isospin asymmetry in
the shell model is an important issue when predicting changes in the shell
structure for exotic nuclei. In many cases pseudospin partner levels, that are
almost degenerate in energy for stable nuclei, are relevant in extracting the
size of the shell gaps. A breaking of the pseudospin symmetry can affect the
size of these gaps and change the magic numbers accordingly. The strength of
the pseudospin splitting is expected to depend in particular on
isovector-dependent and tensor contributions to the effective nuclear
interaction. A description employing supersymmetric quantum mechanics allows to
derive a pseudospin symmetry breaking potential that is regular in contrast to
the pseudospin-orbit potential in the conventional relativistic treatment. The
derived perturbation potential provides a measure to quantify the symmetry
breaking and it can be employed to improve mean-field calculations in order to
better reproduce the experimentally observed shell evolution. General
potentials with exact pseudospin symmetry are obtained that can be used in
relativistic mean-field Hamiltonians.


title:
Towards identification of a non-abelian state: observation of a quarter
  of electron charge at $\nu=5/2$ quantum Hall state

abstract:
  The fractional quantum Hall effect, where plateaus in the Hall resistance at
values of coexist with zeros in the longitudinal resistance, results from
electron correlations in two dimensions under a strong magnetic field. Current
flows along the edges carried by charged excitations (quasi particles) whose
charge is a fraction of the electron charge. While earlier research
concentrated on odd denominator fractional values of $\nu$, the observation of
the even denominator $\nu=5/2$ state sparked a vast interest. This state is
conjectured to be characterized by quasiparticles of charge e/4, whose
statistics is non-abelian. In other words, interchanging of two quasi particles
may modify the state of the system to an orthogonal one, and does not just add
a phase as in for fermions or bosons. As such, these quasiparticles may be
useful for the construction of a topological quantum computer. Here we report
data of shot noise generated by partitioning edge currents in the $\nu=5/2$
state, consistent with the charge of the quasiparticle being e/4, and
inconsistent with other potentially possible values, such as e/2 and e. While
not proving the non-abelian nature of the $\nu=5/2$ state, this observation is
the first step toward a full understanding of these new fractional charges.


title: Weak Solutions for Dislocation Type Equations

abstract:
  We describe recent results obtained by G. Barles, P. Cardaliaguet, R. Monneau
and the author recently. They are concerned with nonlocal Eikonal equations
arising in the study of the dynamics of dislocation lines in crystals. These
equations are nonlocal but also non monotone. We use a notion of weak solution
to provide solutions for all time. Then, we discuss the link between these weak
solutions and the classical viscosity solutions, and state some uniqueness
results in particular cases. A counter-example to uniqueness is given.


title: Homogenization of monotone systems of Hamilton-Jacobi equations

abstract:
  In this paper we study homogenization for a class of monotone systems of
first-order time-dependent periodic Hamilton-Jacobi equations. We characterize
the Hamiltonians of the limit problem by appropriate cell problems. Hence we
show the uniform convergence of the solution of the oscillating systems to the
bounded uniformly continuous solution of the homogenized system.


title: Stochastic equations of non-negative processes with jumps

abstract:
  We study stochastic equations of non-negative processes with jumps. The
existence and uniqueness of strong solutions are established under Lipschitz
and non-Lipschitz conditions. The comparison property of two solutions are
proved under suitable conditions. The results are applied to stochastic
equations driven by one-sided Levy processes and those of continuous state
branching processes with immigration.


title: How Resonances can synchronise with Thresholds

abstract:
  The mechanism by which a threshold may capture a resonance is examined. It
involves a threshold cusp interfering constructively with either or both (i) a
resonance produced via confinement, (ii) attractive t- and u-channel exchanges.
The fo(980), X(3872) and Z(4430) are studied in detail. The fo(980) provides a
valuable model of the locking mechanism. The X(3872) is too narrow to be fitted
by a cusp, and requires either a resonance or virtual state. The Z(4430) can be
fitted as a resonance but also can be fitted successfully by a cusp with no
nearby resonant pole.


title: Note About String with Euclidean World-Sheet in AdS(5)xS(5)

abstract:
  This note is devoted to the study of the classical solutions on the bosonic
string with euclidean world-sheet in AdS(5)xS(5). We generalize solutions
presented in arXiv:0707.4254 [hep-th] to the case where we include the dynamics
of the string on S(5) as well.


title: Progress towards Gravitational Wave Astronomy

abstract:
  I will review the most recent and interesting results from gravitational wave
detection experiments, concentrating on recent results from the LIGO Scientific
Collaboration (LSC). I will outline the methodologies utilized in the searches,
explain what can be said in the case of a null result, what quantities may be
constrained. I will compare these results with prior expectations and discuss
their significance. As I go along I will outline the prospects for future
improvements.


title: Flavor Symmetries, Neutrino Masses and Neutrino Mixing

abstract:
  We discuss the neutrino mixing, using the texture 0 mass matrices, which work
very well for the quarks. The solar mixing angle is directly linked to the mass
ratio of the first two neutrinos. The neutrino masses are hierarchical, but the
mass ratios turn out to be much smaller than for quarks. The atmospheric mixing
angle is 38$^{\circ}$. The CP violation for leptons should be much smaller than
for quarks.


title:
Channeling 5-min photospheric oscillations into the solar outer
  atmosphere through small-scale vertical magnetic flux tubes

abstract:
  We report two-dimensional MHD simulations which demonstrate that photospheric
5-min oscillations can leak into the chromosphere inside small-scale vertical
magnetic flux tubes. The results of our numerical experiments are compatible
with those inferred from simultaneous spectropolarimetric observations of the
photosphere and chromosphere obtained with the Tenerife Infrared Polarimeter
(TIP) at 10830 A. We conclude that the efficiency of energy exchange by
radiation in the solar photosphere can lead to a significant reduction of the
cut-off frequency and may allow for the propagation of the 5 minutes waves
vertically into the chromosphere.


title:
On the classical confinement of test particles to a thin 3-brane in the
  absence of non-gravitational forces

abstract:
  The classical confinement condition of test particles to a brane universe in
the absence of non-gravitational forces is transformed using the
Hamilton-Jacobi formalism. The transformed condition provides a direct
criterion for selecting in a cosmological scenario 5D bulk manifolds wherein it
is possible to obtain confinement of trajectories to 4D hypersurfaces purely
due to classical gravitational effects.


title: La renormalisation dans la theorie non commutative des champs

abstract:
  Non commutative quantum field theory is a possible candidate for the
quantization of gravity. In our thesis we study in detail the $\phi 4$ model on
the Moyal plane with an harmonic potential. Introduced by Grosse and
Wulkenhaar, this model exhibits the Langmann-Szabo duality not only for the
vertex but also for the propagator. We have obtained several results concerning
this model. We have proved the renormalisability of this theory at all orders
in the position space. We have introduced the parametric and Complete Mellin
representation for the model. Furthermore we have proved that the coupling
constant has a bounded flow at all orders in perturbation theory. Finally we
have achieved the dimensional regularization and renormalization of the model.
Further possible studies include the study of gauge theory on the Moyal plane
and there possible applications for the quantization of gravity. The
connections with string theory and loop quantum gravity should also be
investigated.


title:
Dark Matter capture and annihilation on the First Stars: preliminary
  estimates

abstract:
  Assuming that Dark Matter is dominated by WIMPs, it accretes by gravitational
attraction and scattering over baryonic material and annihilates inside
celestial objects, giving rise to a "Dark Luminosity" which may potentially
affect the evolution of stars. We estimate the Dark Luminosity achieved by
different kinds of stars in a halo with DM properties characteristic of the
ones where the first star formation episode occurs. We find that either
massive, metal-free and small, galactic-like stars can achieve Dark
Luminosities comparable or exceeding their nuclear ones. This might have
dramatic effects over the evolution of the very first stars, known as
Population III.


title: General Relativity as Classical Limit of Evolutionary Quantum Gravity

abstract:
  We analyze the dynamics of the gravitational field when the covariance is
restricted to a synchronous gauge. In the spirit of the Noether theorem, we
determine the conservation law associated to the Lagrangian invariance and we
outline that a non-vanishing behavior of the Hamiltonian comes out. We then
interpret such resulting non-zero ``energy'' of the gravitational field in
terms of a dust fluid. This new matter contribution is co-moving to the slicing
and it accounts for the ``materialization'' of a synchronous reference from the
corresponding gauge condition. Further, we analyze the quantum dynamics of a
generic inhomogeneous Universe as described by this evolutionary scheme,
asymptotically to the singularity. We show how the phenomenology of such a
model overlaps the corresponding Wheeler-DeWitt picture. Finally, we study the
possibility of a Schr\"odinger dynamics of the gravitational field as a
consequence of the correspondence inferred between the ensemble dynamics of
stochastic systems and the WKB limit of their quantum evolution. We demonstrate
that the time dependence of the ensemble distribution is associated with the
first order correction in $\hbar$ to the WKB expansion of the energy spectrum.


title:
Physical Mechanism for the Intermediate Characteristic Stellar Mass in
  the Extremely Metal-poor Environments

abstract:
  If a significant fraction of metals is in dust, star-forming cores with
metallicity higher than a critical value ~10^{-6}-10^{-5}Z_sun are able to
fragment by dust cooling, thereby producing low-mass cores. Despite being above
the critical metallicity, a metallicity range is found to exist around
10^{-5}-10^{-4}Z_sun where low-mass fragmentation is prohibited. In this range,
three-body H_2 formation starts at low (~100K) temperature and thus the
resulting heating causes a dramatic temperature jump, which makes the central
part of the star-forming core transiently hydrostatic and thus highly
spherical. With little elongation, the core does not experience fragmentation
in the subsequent dust-cooling phase. The minimum fragmentation mass is set by
the Jeans mass just before the H_2 formation heating, and its value can be as
high as ~10M_sun. For metallicity higher than ~10^{-4}Z_sun, H_2 formation is
almost completed by the dust-surface reaction before the onset of the
three-body reaction, and low-mass star formation becomes possible. This
mechanism might explain the higher characteristic mass of metal-poor stars than
in the solar neighborhood presumed from the statistics of carbon-enhanced
stars.


title: On the origin and evolutionary state of RZ Cas, KO Aql and S Equ

abstract:
  Aims. Determination of the present evolutionary state and the restrictions on
the initial mass ratios of RZ Cas, KO Aql and S Equ. Methods. Comparison of
mass gaining stars with evolutionary models of single stars with the same mass
and subsequent comparison with accretion tracks from simultaneous conservative
binary evolution. Results. The gainers are in an early main sequence stage (Xc
greater than 0.5), with KO Aql being almost unevolved (assuming quasi-thermal
equilibrium). The initial donor/gainer mass ratios Mdi/Mgi must be larger than
three to obtain the present mass and luminosity of the gainers.


title:
Transmission through a defect in polyacene: the extreme limit of ultra
  narrow graphene

abstract:
  We compute the transmission of an electron through an impurity in polyacene.
An analytical expression for the transmission coefficient is found. For
simplicity the disorder is confined to a single unit cell, but the
generalization to several unit cells is straightforward. Both on-site and
off-diagonal defects are considered. When the impurity preserves the inversion
symmetry around the central axis, the scattering problem can be reduced to that
of two independent chains with an alternating sequence of two types of atoms.


title: Bernstein-Heinz-Chern results in calibrated manifolds

abstract:
  Given $(\bar{M},\Omega)$ a calibrated Riemannian manifold with a parallel
calibration of rank $m$, and $M^m$ an immersed orientable submanifold with
parallel mean curvature $H$ we prove that if $\cos \theta$ is bounded away from
zero, where $\theta$ is the $\Omega$-angle of $M$, and if $M$ has zero Cheeger
constant, then $M$ is minimal. In the particular case $M$ is complete with
  $Ricc^M\geq 0$ we may replace the boundedness condition on $\cos \theta$ by
$\cos \theta\geq Cr^{-\beta}$, when $r\to +\infty$, where $ 0\leq\beta <1 $ and
$C > 0$ are constants and $r$ is the distance function to a point in $M$. Our
proof is surprisingly simple and extends to a very large class of submanifolds
in calibrated manifolds, in a unified way, the problem started by Heinz and
Chern of estimating the mean curvature of graphic hypersurfaces in Euclidean
spaces. It is based on a estimation of $\|H\|$ in terms of $\cos\theta$ and an
isoperimetric inequality. We also give some conditions to conclude $M$ is
totally geodesic. We study some particular cases.


title: Iteration of the rational function z-1/z and a Hausdorff moment sequence

abstract:
  In a previous paper we considered a positive function f, uniquely determined
for s>0 by the requirements f(1)=1, log(1/f) is convex and the functional
equation f(s)=psi(f(s+1)) with psi(s)=s-1/s. We prove that the meromorphic
extension of f to the whole complex plane is given by the formula
f(z)=lim_{n\to\infty}psi^{\circ n}(lambda_n(lambda_{n+1}/lambda_n)^z), where
the numbers lambda_n are defined by lambda_0=0 and the recursion
lambda_{n+1}=(1/2)(lambda_n+sqrt{lambda_n^2+4}). The numbers m_n=1/lambda_{n+1}
form a Hausdorff moment sequence of a probability measure \mu such that \int
t^{z-1}d\mu(t)=1/f(z)


title: Cluster decay in very heavy nuclei in Relativistic Mean Field

abstract:
  Exotic cluster decay of very heavy nuclei has been studied in the microscopic
Super-Asymmetric Fission Model. Relativistic Mean Field model with the force
FSU Gold has been employed to obtain the densities of the cluster and the
daughter nuclei. The microscopic nuclear interaction DDM3Y1, which has an
exponential density dependence, and the Coulomb interaction have been used in
the double folding model to obtain the potential between the cluster and the
daughter. Half life values have been calculated in the WKB approximation and
the spectroscopic factors have been extracted. The latter values are seen to
have a simple dependence of the mass of the cluster as has been observed
earlier. Predictions have been made for some possible decays.


title: Bounding the Minimal 331 Model through the Decay B -> X_s gamma

abstract:
  We study the decay B -> X_s gamma within the framework of the minimal 331
model, taking into account both new experimental and theoretical developments
that allow us to update and improve on an existing ten year old analysis. In
contrast to several other flavor changing observables that are modified already
at tree level from a new Z' gauge boson, we have only one loop contributions in
this case. Nevertheless, these are interesting, as they may be enhanced and can
shed light on the charged gauge boson and Higgs sector of the model.
Numerically, we find that the Higgs sector, which is well approximated by a 2
Higgs doublet model (2HDM), dominates, since the gauge contributions are
already very strongly constrained. With respect to B -> X_s gamma, the signal
of the minimal 331 model is therefore nearly identical to the 2HDM one, which
allows us to obtain a lower bound on the charged Higgs mass. Further, we
observe, in analogy to the 2HDM model, that the branching fraction can be
rather strongly increased for small values of tan beta. Also, we find that B ->
X_s gamma has no impact on the bounds obtained on rare K and B decays in an
earlier analysis.


title: The curvature of contact structure on 3-manifolds

abstract:
  We study the sectional curvature of plane distributions on 3-manifolds. We
show that if the distribution is a contact structure it is easy to manipulate
this curvature. As a corollary we obtain that for every transversally oriented
contact structure on a closed 3-dimensional manifold $M$ there is a metric,
such that the sectional curvature of the contact distribution is equal to -1.
We also introduce the notion of Gaussian curvature of the plane distribution.
For this notion of curvature we get the similar results.


title:
Disk illumination by black hole superradiance of electromagnetic
  perturbations

abstract:
  Using the Kerr-Schild formalism to solve the Einstein-Maxwell equations, we
study energy transport due to time-dependent electromagnetic perturbations
around a Kerr black hole, which may work as a mechanism to illuminate a disk
located on the equatorial plane. For such a disk-hole system it is found that
the energy extraction from the hole can occur under the well-known
superradiance condition for wave frequency, even though the energy absorption
into the hole should be rather dominant near the polar region of the horizon.
We estimate the efficiency of the superradiant amplification of the disk
illumination. Further we calculate the time-averaged energy density
distribution to show explicitly the existence of a negative energy region near
the horizon and to discuss the possible generation of a hot spot on the disk.


title: Dimensions of triangulated categories via Koszul objects

abstract:
  Lower bounds for the dimension of a triangulated category are provided. These
bounds are applied to stable derived categories of Artin algebras and of
commutative complete intersection local rings. As a consequence, one obtains
bounds for the representation dimensions of certain Artin algebras.


title:
The Topological Directional Entropy of Z^2-actions Generated by Linear
  Cellular Automata

abstract:
  In this paper we study the topological and metric directional entropy of
$\mathbb{Z}^2$-actions by generated additive cellular automata (CA hereafter),
defined by a local rule $f[l, r]$, $l, r\in \mathbb{Z}$, $l\leq r$, i.e. the
maps $T_{f[l, r]}: \mathbb{Z}^\mathbb{Z}_{m} \to \mathbb{Z}^\mathbb{Z}_{m}$
which are given by $T_{f[l, r]}(x) =(y_n)_ {-\infty}^{\infty}$, $y_{n} =
f(x_{n+l}, ..., x_{n+r}) = \sum_{i=l}^r\lambda_{i}x_{i+n}(mod m)$, $x=(x_n)_
{n=-\infty}^{\infty}\in \mathbb{Z}^\mathbb{Z}_{m}$, and $f:
\mathbb{Z}_{m}^{r-l+1}\to \mathbb{Z}_{m}$, over the ring $\mathbb{Z}_m (m \geq
2)$, and the shift map acting on compact metric space
$\mathbb{Z}^\mathbb{Z}_{m}$, where $m$ $(m \geq2)$ is a positive integer. Our
main aim is to give an algorithm for computing the topological directional
entropy of the $\mathbb{Z}^2$-actions generated by the additive CA and the
shift map. Thus, we ask to give a closed formula for the topological
directional entropy of $\mathbb{Z}^2$-action generated by the pair $(T_{f[l,
r]}, \sigma)$ in the direction $\theta$ that can be efficiently and rightly
computed by means of the coefficients of the local rule f as similar to [Theor.
Comput. Sci. 290 (2003) 1629-1646]. We generalize the results obtained by Ak\i
n [The topological entropy of invertible cellular automata, J. Comput. Appl.
Math. 213 (2) (2008) 501-508] to the topological entropy of any invertible
linear CA.


title: Rational Equivariant Spectra

abstract:
  We develop model categories of rational equivariant spectra whose homotopy
categories are equivalent to the category of rational equivariant cohomology
theories. We prove that given an orthogonal decomposition of the unit in the
rational Burnside ring, the model category of rational equivariant spectra
decomposes into a product of localisations. We use this result to reprove the
classification of rational equivariant cohomology theories for finite groups
and to study such cohomology theories for the group O(2). We then concentrate
on a split piece of the O(2) case and relate it to rational SO(2) equivariant
spectra.


title: Multiwell rigidity in nonlinear elasticity

abstract:
  We derive a quantitative rigidity estimate for a multiwell problem in
nonlinear elasticity. Precisely, we show that if a gradient field is L^1-close
to a set of the form SO(n)U_1 \cup ... \cup SO(n)U_l, and an appropriate bound
on the length of the interfaces holds, then the gradient field is actually
close to only one of the wells SO(n)U_i. The estimate holds for any connected
subdomain, and has the optimal scaling.


title: Multiplicity of photohadronization and photon--hadron scaling violation

abstract:
  The method of scaling transformations permitting to carry out the
reconstruction of cross sections of $\gamma N$ and $\gamma\gamma$ interactions
on the basis of cross sections of nucleon-(anti)nucleon interactions is
suggested. The photon--hadron scaling violation is a consequence of dependence
of scaling transformation parameter $\bar n(s)$ on the energy. The universal
function $\bar n(s)$ is interpreted as the multiplicity of photohadronization.
This function is established by processing the data on $\gamma p$ cross
sections in the low energy region $\sqrt{s}< 20 \GeV$ and is extrapolated to
the high energy region up to $\sqrt{s}\sim 200 \GeV$. The results of the
reconstruction of $\gamma N$ cross sections at high energies and of
$\gamma\gamma$ ones at all energies are in a remarkable agreement with
available experimental data.


title:
Unraveling the dynamics and kinematics of GRB hosts with high resolution
  spectroscopy

abstract:
  In the last years the research on GRB host galaxies has proceeded to more
detailed studies both using high resolution afterglow spectroscopy and
spatially resolved spectra of nearby hosts. High resolution spectra give a
detailed picture of the kinematic properties of matter along the line-of-sight
in the host. Two afterglow spectra show clear indications for outflows from
their host, namely GRB 030329 and GRB 060206, derived from the position of
absorption and host emission lines, nonvariability of Mg I and the radiation
field calculated from fine-structure line detections. In nearby GRB hosts it is
possible to resolve the actual GRB site. GRB 060505, a SN-less GRB, originated
in a relatively metal poor, star forming region with similar properties as
other long-duration hosts. A similar conclusion is reached for the site of GRB
980425/SN 1998bw.


title:
Spin-wave interaction in two-dimensional ferromagnets with dipolar
  forces

abstract:
  We discuss the spin-wave interaction in two-dimensional (2D) Heisenberg
ferromagnet (FM) with dipolar forces at $T_C\gg T\ge0$ using 1/S expansion. A
comprehensive analysis is carried out of the first 1/S corrections to the
spin-wave spectrum. In particular, similar to 3D FM discussed in our previous
paper A.V. Syromyatnikov, PRB {\bf 74}, 014435 (2006), we obtain that the
spin-wave interaction leads to the {\it gap} in the spectrum $\epsilon_{\bf k}$
renormalizing greatly the bare gapless spectrum at small momenta $k$.
Expressions for the spin-wave damping $\Gamma_{\bf k}$ are derived
self-consistently and it is concluded that magnons are well-defined
quasi-particles in both quantum and classical 2D FMs at small $T$. We observe
thermal enhancement of both $\Gamma_{\bf k}$ and $\Gamma_{\bf k}/\epsilon_{\bf
k}$ at small momenta. In particular, a peak appears in $\Gamma_{\bf k}$ and
$\Gamma_{\bf k}/\epsilon_{\bf k}$ at small $k$ and at any given direction of
$\bf k$. If $S\sim1$ the height of the peak in $\Gamma_{\bf k}/\epsilon_{\bf
k}$ is not larger than a value proportional to $T/D\ll1$, where $D$ is the
spin-wave stiffness. In the case of large spins $S\gg1$ the peak in
$\Gamma_{\bf k}/\epsilon_{\bf k}$ cannot be greater than that of the classical
2D FM found at $k=0$ which height is small only {\it numerically}: $\Gamma_{\bf
0}/\epsilon_{\bf 0}\approx0.16$ for the simple square lattice. Frustrating
next-nearest-neighbor exchange coupling increases $\Gamma_{\bf 0}/\epsilon_{\bf
0}$ in classical 2D FM only slightly. We find expressions for spin Green's
functions and the magnetization. The latter differs from the well-known result
by S.V. Maleev, Sov. Phys. JETP {\bf 43}, 1240 (1976). The effect of the
exchange anisotropy is also discussed briefly.


title:
A geometrical approach to Gordan--Noether's and Franchetta's
  contributions to a question posed by Hesse

abstract:
  Hesse claimed that an irreducible projective hypersurface in $\PP^n$ defined
by an equation with vanishing hessian determinant is necessarily a cone. Gordan
and Noether proved that this is true for $n\leq 3$ and constructed
counterexamples for every $n\geq 4$. Gordan and Noether and Franchetta gave
classification of hypersurfaces in $\PP^4$ with vanishing hessian and which are
not cones. Here we translate in geometric terms Gordan and Noether approach,
providing direct geometrical proofs of these results.


title:
Regularity and Cohomological Splitting Conditions for Vector Bundles on
  Multiprojective Spaces

abstract:
  Here we give a definition of regularity on multiprojective spaces which is
different from the definitions of Hoffmann-Wang and Costa-Mir\'o Roig. By using
this notion we prove some splitting criteria for vector bundles.


title:
Toward first-principle simulations of galaxy formation: I. How should we
  choose star formation criteria in high-resolution simulations of disk
  galaxies?

abstract:
  We performed 3-dimensional N-body/SPH simulations to study how mass
resolution and other model parameters such as the star formation efficiency
parameter, C* and the threshold density, nth affect structures of the galactic
gaseous/stellar disk in a static galactic potential. We employ 10^6 - 10^7
particles to resolve a cold and dense (T < 100 K & n_H > 100 cm^{-3}) phase. We
found that structures of the ISM and the distribution of young stars are
sensitive to the assumed nth. High-nth models with nth = 100 cm^{-3} yield
clumpy multi-phase features in the ISM. Young stars are distributed in a thin
disk of which half-mass scale height is 10 - 30 pc. In low-nth models with nth
= 0.1 cm^{-3}, the stellar disk is found to be several times thicker, and the
gas disk appears smoother than the high-nth models. A high-resolution
simulation with high-nth is necessary to reproduce the complex structure of the
gas disk. The global properties of the model galaxies in low-nth models, such
as star formation histories, are similar to those in the high-nth models when
we tune the value of C* so that they reproduce the observed relation between
surface gas density and surface star formation rate density. We however
emphasize that high-nth models automatically reproduce the relation, regardless
of the values of C*. The ISM structure, phase distribution, and distributions
of young star forming region are quite similar between two runs with values of
C* which differ by a factor of 15. We also found that the timescale of the flow
from n_H ~1 cm^{-3} to n_H > 100 cm^{-3} is about 5 times as long as the local
dynamical time and is independent of the value of C*. The use of a high-nth
criterion for star formation in high-resolution simulations makes numerical
models fairy insensitive to the modelling of star formation. (Abridged)


title: Morphological Analysis of Cryogenic Spray Images

abstract:
  This study gives the development of a new technique for analyzing images of
Cryogenic sprays, to estimate the drop-size distribution. It has a sound
mathematical basis, in the form of Mathematical Morphology, and we have tried
to build up a formulation for a granulometry, starting from the elementary
operations of Dilation and Erosion. An axiomatic foundation for granulometry
has also been discussed. We have taken an actual LN2 spray photograph for
analysis, to illustrate the use of Morphological operations, culminating in a
granulometry.


title:
Differential operators for harmonic weak Maass forms and the vanishing
  of Hecke eigenvalues

abstract:
  For integers $k\geq 2$, we study two differential operators on harmonic weak
Maass forms of weight $2-k$. The operator $\xi_{2-k}$ (resp. $D^{k-1}$) defines
a map to the space of weight $k$ cusp forms (resp. weakly holomorphic modular
forms). We leverage these operators to study coefficients of harmonic weak
Maass forms. Although generic harmonic weak Maass forms are expected to have
transcendental coefficients, we show that those forms which are "dual" under
$\xi_{2-k}$ to newforms with vanishing Hecke eigenvalues (such as CM forms)
have algebraic coefficients. Using regularized inner products, we also
characterize the image of $D^{k-1}$.


title: Least angle and $\ell_1$ penalized regression: A review

abstract:
  Least Angle Regression is a promising technique for variable selection
applications, offering a nice alternative to stepwise regression. It provides
an explanation for the similar behavior of LASSO ($\ell_1$-penalized
regression) and forward stagewise regression, and provides a fast
implementation of both. The idea has caught on rapidly, and sparked a great
deal of research interest. In this paper, we give an overview of Least Angle
Regression and the current state of related research.


title: Dipole and quadrupole polarizabilities of the pion

abstract:
  Data on pion polarizabilities obtained in different experiments are reviewed.
The values of the dipole and quadrupole polarizabilities of the pi^0 and
pi^{+-} mesons found are compared with predictions of dispersion sum rules
(DSRs) and two-loop calculations in the framework of chiral perturbation theory
(ChPT). Possible reasons of a difference between the predictions of DSRs and
ChPT are discussed.


title:
Existence of non-trivial harmonic functions on Cartan-Hadamard manifolds
  of unbounded curvature

abstract:
  The Liouville property of a complete Riemannian manifold (i.e., the question
whether there exist non-trivial bounded harmonic functions) attracted a lot of
attention. For Cartan-Hadamard manifolds the role of lower curvature bounds is
still an open problem. We discuss examples of Cartan-Hadamard manifolds of
unbounded curvature where the limiting angle of Brownian motion degenerates to
a single point on the sphere at infinity, but where nevertheless the space of
bounded harmonic functions is as rich as in the non-degenerate case. To see the
full boundary the point at infinity has to be blown up in a non-trivial way.
Such examples indicate that the situation concerning the famous conjecture of
Greene and Wu about existence of non-trivial bounded harmonic functions on
Cartan-Hadamard manifolds is much more complicated than one might have
expected.


title:
Acceleration and Deceleration in Curvature Induced Phantom Model of the
  Late and Future Universe, Cosmic Collapse as Well as its Quantum Escape

abstract:
  Here, cosmology of the late and future universe is obtained from
$f(R)$-gravity with non-linear curvature terms $R^2$ and $R^3$ ($R$ being the
Ricci scalar curvature). It is different from $f(R)$-dark enrgy models, where
non-linear curvature terms are taken as gravitational alternative of dark
energy. In the present model, neither linear nor no-linear curvature terms are
taken as dark energy. Rather, dark energy terms are induced by curvature terms
in the Friedmann equation derived from $f(R)$-gravitational equations. It has
advantage over $f(R)$- dark energy models in the sense that the present model
satisfies WMAP results and expands as $\sim t^{2/3}$ during matter-dominance.
So, it does not have problems due to which $f(R)$-dark energy models are
criticized. Curvature-induced dark energy, obtained here, mimics phantom.
Different phases of this model, including acceleration and deceleration during
phantom phase, are investigated here.It is found that expansion of the universe
will stop at the age $(3.87 t_0 + 694.4 {\rm kyr})$ ($t_0$ being the present
age of the universe) and after this epoch, it will contract and collapse by the
time $(336.87 t_0 + 694.4 {\rm kyr})$. Further,it is shown that universe will
escape predicted collapse (obtained using classical mechanics) on making
quantum gravity corrections relevant near collapse time due to extremely high
energy density and large curvature analogous to the state of very early
universe. Interestingly, cosmological constant is also induced here, which is
very small in classical domain, but very high in quantum domain.


title: Structure Function Resummation in small-x QCD

abstract:
  We summarize our recent results on small x resummation in full QCD with n_f
quark flavours and discuss their phenomenological impact in the extraction of
parton distributions from present day structure function data and their
extrapolation to the kinematics relevant for future colliders such as the LHC.


title:
Sensory supplementation system based on electrotactile tongue
  biofeedback of head position for balance control

abstract:
  The present study aimed at investigating the effects of an artificial head
position-based tongue-placed electrotactile biofeedback on postural control
during quiet standing under different somatosensory conditions from the support
surface. Eight young healthy adults were asked to stand as immobile as possible
with their eyes closed on two Firm and Foam support surface conditions executed
in two conditions of No-biofeedback and Biofeedback. In the Foam condition, a
6-cm thick foam support surface was placed under the subjects' feet to alter
the quality and/or quantity of somatosensory information at the plantar sole
and the ankle. The underlying principle of the biofeedback consisted of
providing supplementary information about the head orientation with respect to
gravitational vertical through electrical stimulation of the tongue. Centre of
foot pressure (CoP) displacements were recorded using a force platform. Larger
CoP displacements were observed in the Foam than Firm conditions in the two
conditions of No-biofeedback and Biofeedback. Interestingly, this destabilizing
effect was less accentuated in the Biofeedback than No-biofeedback condition.
In accordance with the sensory re-weighting hypothesis for balance control, the
present findings evidence that the availability of the central nervous system
to integrate an artificial head orientation information delivered through
electrical stimulation of the tongue to limit the postural perturbation induced
by alteration of somatosensory input from the support surface.


title:
Dynamic structure factor of Luttinger liquids with quadratic energy
  dispersion and long-range interactions

abstract:
  We calculate the dynamic structure factor S (omega, q) of spinless fermions
in one dimension with quadratic energy dispersion k^2/2m and long range
density-density interaction whose Fourier transform f_q is dominated by small
momentum-transfers q << q_0 << k_F. Here q_0 is a momentum-transfer cutoff and
k_F is the Fermi momentum. Using functional bosonization and the known
properties of symmetrized closed fermion loops, we obtain an expansion of the
inverse irreducible polarization to second order in the small parameter q_0 /
k_F. In contrast to perturbation theory based on conventional bosonization, our
functional bosonization approach is not plagued by mass-shell singularities.
For interactions which can be expanded as f_q = f_0 + f_0^{2} q^2/2 + O (q^4)
with finite f_0^{2} we show that the momentum scale q_c = 1/ | m f_0^{2} |
separates two regimes characterized by a different q-dependence of the width
gamma_q of the collective zero sound mode and other features of S (omega, q).
For q_c << q << k_F we find that the line-shape in this regime is
non-Lorentzian with an overall width gamma_q of order q^3/(m q_c) and a
threshold singularity at the lower edge.


title: Pion Compton scattering and bremsstrahlung

abstract:
  The pion-polarizability functions are structure functions of pion-Compton
scattering. They can be assessed in high-energy pion-nucleus bremsstrahlung
reactions, $\pi^- +A\to\pi^- +\gamma +A$. We present numerical expectations for
pion-nucleus bremsstrahlung cross sections in the Coulomb region, i.e. the
small-angle region where the nuclear scattering is dominated by the Coulomb
interaction. We investigate the prospects of measuring the polarizability
functions for pion-Compton c.m. energies from threshold up to 1 GeV. A
meson-exchange model is used for the pion-Compton amplitude.


title:
Actions of vanishing homogeneity rank on quaternionic-Kaehler projective
  spaces

abstract:
  We classify isometric actions of compact Lie groups on quaternionic-K\"ahler
projective spaces with vanishing homogeneity rank. We also show that they are
not in general quaternion-coisotropic.


title: Emergent Gravity, Matrix Models and UV/IR Mixing

abstract:
  We verify explicitly that UV/IR mixing for noncommutative gauge theory can be
understood in terms of an induced gravity action, as predicted by the
identification [1] of gravity within matrix models of NC gauge theory. More
precisely, we obtain the Einstein-Hilbert action by integrating out a scalar
field in the adjoint. It arises from the well-known UV/IR mixing of NC gauge
theory, which is carefully re-analyzed and interpreted in terms of gravity. The
matrix model therefore contains gravity as an IR effect, due to UV/IR mixing.


title: Branching Laws for Some Unitary Representations of SL(4,R)

abstract:
  In this paper we consider the restriction of a unitary irreducible
representation of type $A_{\mathfrak q}(\lambda)$ of $GL(4,{\mathbb R})$ to
reductive subgroups $H$ which are the fixpoint sets of an involution. We obtain
a formula for the restriction to the symplectic group and to $GL(2,{\mathbb
C})$, and as an application we construct in the last section some
representations in the cuspidal spectrum of the symplectic and the complex
general linear group. In addition to working directly with the cohmologically
induced module to obtain the branching law, we also introduce the useful
concept of pseudo dual pairs of subgroups in a reductive Lie group.


title: On the Dynamical Origin of the ICM Metallicity Evolution

abstract:
  We present a study on the origin of the metallicity evolution of the
intra-cluster medium (ICM) by applying a semi-analytic model of galaxy
formation to N-body/SPH (smoothed particle hydrodynamic) non-radiative
numerical simulations of clusters of galaxies. The semi-analytic model includes
gas cooling, star formation, supernovae feedback and metal enrichment, and is
linked to the diffuse gas of the underlying simulations so that the chemical
properties of gas particles are dynamically and consistently generated from
stars in the galaxies. This hybrid model let us have information on the spatial
distribution of metals in the ICM. The results obtained for a set of clusters
with virial masses of ~1.5*10^15 h^{-1} M_sun contribute to the theoretical
interpretation of recent observational X-ray data, which indicate a decrease of
the average iron content of the intra-cluster gas with increasing redshift. We
find that this evolution arises mainly as a result of a progressive increase of
the iron abundance within ~0.15 R_vir. The clusters have been considerably
enriched by z~1 with very low contribution from recent star formation. Low
entropy gas that has been enriched at high redshift sinks to the cluster centre
contributing to the evolution of the metallicity profiles.


title: Anderson localization from classical trajectories

abstract:
  We show that Anderson localization in quasi-one dimensional conductors with
ballistic electron dynamics, such as an array of ballistic chaotic cavities
connected via ballistic contacts, can be understood in terms of classical
electron trajectories only. At large length scales, an exponential
proliferation of trajectories of nearly identical classical action generates an
abundance of interference terms, which eventually leads to a suppression of
transport coefficients. We quantitatively describe this mechanism in two
different ways: the explicit description of transition probabilities in terms
of interfering trajectories, and an hierarchical integration over fluctuations
in the classical phase space of the array cavities.


title: Mixing and lifetimes of $b$-hadrons

abstract:
  We review the status of mixing and lifetimes of $b$-hadrons. We will show
that $\Delta \Gamma / \Delta M$, $a_{sl}$ and $\phi$ are better suited to
search for new physics effects than $\Delta M$ alone, because of our poor
knowledge of the decay constants. The theoretical precision in the
determination of $\Gamma_{12} / M_{12}$ - which contains all information on
$\Delta \Gamma / \Delta M$, $a_{sl}$ and $\phi$ - can be tested directly by
investigating the lifetimes of $b$-hadrons, because both quantities rely on the
same theoretical footing. In particular we will also present a numerical
estimate for the lifetime of the $\Xi_b$-baryon.


title:
Minimal classes on the intermediate Jacobian of a generic cubic
  threefold

abstract:
  Let X be a smooth cubic threefold. We can associate two objects to X: the
intermediate Jacobian J and the Fano surface F parametrising lines on X. By a
theorem of Clemens and Griffiths, the Fano surface can be embedded in the
intermediate Jacobian and the cohomology class of its image is minimal. In this
paper we show that if X is generic, the Fano surface is the only surface of
minimal class in J.


title: Computing Hilbert Class Polynomials

abstract:
  We present and analyze two algorithms for computing the Hilbert class
polynomial $H_D$ . The first is a p-adic lifting algorithm for inert primes p
in the order of discriminant D < 0. The second is an improved Chinese remainder
algorithm which uses the class group action on CM-curves over finite fields.
Our run time analysis gives tighter bounds for the complexity of all known
algorithms for computing $H_D$, and we show that all methods have comparable
run times.


title: Determination of QCD condensates from tau-decay data

abstract:
  We have used the latest data from the ALEPH Collaboration to extract values
for QCD condensates up to dimension d=12 in the V-A channel and up to dimension
d=8 in the V, A and V+A channels. Performing 2- and 3-parameter fits, we obtain
new results for the correlations of condensates. The results are consistent
among themselves and agree with most of the previous results found in the
literature.


title: A Unified Theory on Some Basic Topological Concepts

abstract:
  Several mathematicians, including myself, have studied some unifications in
general topological spaces as well as in fuzzy topological spaces. For instance
in our earlier works, using operations on topological spaces, we have tried to
unify some concepts similar to continuity, openness, closedness of functions,
compactness, filter convergence, closedness of graphs, countable compactness
and Lindelof property. In this article, to obtain further unifications, we will
study $\phi_{1,2}$-compactness and relations between $\phi_{1,2}$-compactness,
filters and $\phi_{1,2}$% -closure operator.


title:
Spin-polarized current and shot noise in the presence of spin flip in a
  quantum dot via nonequilibrium Green's functions

abstract:
  Using non-equilibrium Green functions we calculate the spin-polarized current
and shot noise in a ferromagnet--quantum-dot--ferromagnet (FM-QD-FM) system.
Both parallel (P) and antiparallel (AP) magnetic configurations are considered.
Coulomb interaction and coherent spin-flip (similar to a transverse magnetic
field) are taken into account within the dot. We find that the interplay
between Coulomb interaction and spin accumulation in the dot can result in a
bias-dependent current polarization $\wp$. In particular, $\wp$ can be
suppressed in the P alignment and enhanced in the AP case depending on the bias
voltage. The coherent spin-flip can also result in a switch of the current
polarization from the emitter to the collector lead. Interestingly, for a
particular set of parameters it is possible to have a polarized current in the
collector and an unpolarized current in the emitter lead. We also found a
suppression of the Fano factor to values well below 0.5.


title: Optimising large galaxy surveys for ISW detection

abstract:
  We report on investigations of the power of next generation cosmic microwave
background and large scale structure surveys in constraining the nature of dark
energy through the cross-correlation of the Integrated Sachs Wolfe effect and
the galaxy distribution. First we employ a signal to noise analysis to find the
most appropriate properties of a survey in order to detect the correlated
signal at a level of more than 4 sigma: such a survey should cover more than
35% of the sky, the galaxy distribution should be probed with a median redshift
higher than 0.8, and the number of galaxies detected should be higher than a
few per squared arcmin. We consider the forthcoming surveys DUNE, LSST, SNAP,
PanSTARRS. We then compute the constraints that the DUNE survey can put on the
nature of dark energy (through different parametrizations of its equation of
state) with a standard Fisher matrix analysis. We confirm that, with respect to
pure CMB constraints, cross-correlation constraints help in breaking
degeneracies among the dark energy and the cosmological parameters. Naturally,
the constraining capability is not independent of the choice of the dark energy
model. Despite being weaker than some other probes (like Gravitational
Weak-Lensing), these constraints are complementary to them, being sensitive to
the high-redshift behaviour of the dark energy.


title: Moving Mini-Max - a new indicator for technical analysis

abstract:
  We propose a new indicator for technical analysis. The indicator emphasizes
maximums and minimums in price series with inherent smoothing and has a
potential to be useful in both mechanical trading rules and chart pattern
analysis.


title: Polarization in Hyperon Photo- and Electro- Production

abstract:
  Multiple polarization observables must be measured to access the amplitude
structure of pseudoscalar meson photoproduction off the proton. The
hyperon-producing reactions are especially attractive to study, since the weak
decays allow straightforward measurement of the induced and recoil polarization
observables. In this paper we emphasize $\gamma + p \to K^+ + \Lambda$,
discussing recent measurements of $C_x$, $C_z$, and $P$ for this reaction. An
empirical constraint on the helicity amplitudes is obtained. A simplified model
involving spin-flip and spin non-flip amplitudes is presented. Finally, a
semi-classical model of how the polarization may arise is presented.


title: On the structure of Hardy-Sobolev-Maz'ya inequalities

abstract:
  In this article we establish new improvements of the optimal Hardy inequality
in the half space. We first add all possible linear combinations of Hardy type
terms thus revealing the structure of this type of inequalities and obtaining
best constants. We then add the critical Sobolev term and obtain necessary and
sufficient conditions for the validity of Hardy-Sobolev-Maz'ya type
inequalities.


title: Progress in atom chips and the integration of optical microcavities

abstract:
  We review recent progress at the Centre for Cold Matter in developing atom
chips. An important advantage of miniaturizing atom traps on a chip is the
possibility of obtaining very tight trapping structures with the capability of
manipulating atoms on the micron length scale. We recall some of the pros and
cons of bringing atoms close to the chip surface, as is required in order to
make small static structures, and we discuss the relative merits of metallic,
dielectric and superconducting chip surfaces. We point out that the addition of
integrated optical devices on the chip can enhance its capability through
single atom detection and controlled photon production. Finally, we review the
status of integrated microcavities that have recently been demonstrated at our
Centre and discuss their prospects for future development.


title:
Unveiling the nature of INTEGRAL objects through optical spectroscopy.
  VI. A multi-observatory identification campaign

abstract:
  Using 8 telescopes in the northern and southern hemispheres, plus archival
data from two on-line sky surveys, we performed a systematic optical
spectroscopic study of 39 putative counterparts of unidentified or poorly
studied INTEGRAL sources in order to determine or at least better assess their
nature. This was implemented within the framework of our campaign to reveal the
nature of newly-discovered and/or unidentified sources detected by INTEGRAL.
Our results show that 29 of these objects are active galactic nuclei (13 of
which are of Seyfert 1 type, 15 are Seyfert 2 galaxies and one is possibly a BL
Lac object) with redshifts between 0.011 and 0.316, 7 are X-ray binaries (5
with high-mass companions and 2 with low-mass secondaries), one is a magnetic
cataclysmic variable, one is a symbiotic star and one is possibly an active
star. Thus, the large majority (74%) of the identifications in this sample
belongs to the AGN class. When possible, the main physical parameters for these
hard X-ray sources were also computed using the multiwavelength information
available in the literature. These identifications further underscore the
importance of INTEGRAL in studying the hard X-ray spectra of all classes of
X-ray emitting objects, and the effectiveness of a strategy of multi-catalogue
cross-correlation plus optical spectroscopy to securely pinpoint the actual
nature of still unidentified hard X-ray sources.


title: Modification of the $\omega$-Meson Lifetime in Nuclear Matter

abstract:
  The photo production of $\omega$ mesons on the nuclei C, Ca, Nb and Pb has
been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon
facility in Bonn. The dependence of the $\omega$ meson cross section on the
nuclear mass number has been compared with three different types of models, a
Glauber analysis, a BUU analysis of the Giessen theory group and a calculation
by the Valencia theory group. In all three cases, the inelastic $\omega$ width
is found to be $130-150 \rm{MeV/c^2}$ at normal nuclear matter density for an
average 3-momentum of 1.1 GeV/c. In the restframe of the $\omega$ meson, this
inelastic $\omega$ width corresponds to a reduction of the $\omega$ lifetime by
a factor $\approx 30$. For the first time, the momentum dependent $\omega$N
cross section has been extracted from the experiment and is in the range of 70
mb.