title:
Ultracold Bose gases in time-dependent 1D superlattices: response and
  quasimomentum structure

abstract:
  The response of ultracold atomic Bose gases in time-dependent optical
lattices is discussed based on direct simulations of the time-evolution of the
many-body state in the framework of the Bose-Hubbard model. We focus on
small-amplitude modulations of the lattice potential as implemented in several
recent experiment and study different observables in the region of the first
resonance in the Mott-insulator phase. In addition to the energy transfer we
investigate the quasimomentum structure of the system which is accessible via
the matter-wave interference pattern after a prompt release. We identify
characteristic correlations between the excitation frequency and the
quasimomentum distribution and study their structure in the presence of a
superlattice potential.


title: Free flux flow magneto-resistance of single crystal BSCCO

abstract:
  Measurement of the free flux flow resistance in monocrystalline highly
anisotropic BSCCO reveals a low field magneto-resistive effect nearly 100 times
that expected from a naive application of the Bardeen-Stephen rule R/Rn =
B/Bc2. Furthermore in the vortex solid phase it saturates to a constant value
at about Hc2/100 as if the vortices were moving 100 times faster than expected.
An attempt to account for this behavior by a combination of sheared planar
vortex flow obeying the BS rule and the quasi-particle c axis conductivity
between the Josephson coupled superconducting planes is only partially
successful. In particular it is unable to account for the saturation feature
which occurs in both optimally and underdoped samples in the low temperature
vortex solid phase.


title: The Heisenberg group and conformal field theory

abstract:
  A mathematical construction of the conformal field theory (CFT) associated to
a compact torus, also called the "nonlinear Sigma-model" or "lattice-CFT", is
given. Underlying this approach to CFT is a unitary modular functor, the
construction of which follows from a "Quantization commutes with reduction"-
type of theorem for unitary quantizations of the moduli spaces of holomorphic
torus-bundles and actions of loop groups. This theorem in turn is a consequence
of general constructions in the category of affine symplectic manifolds and
their associated generalized Heisenberg groups.


title: CP violation in the B0s system

abstract:
  In this paper the most recent Tevatron results concerning CP violation in the
B0s system are reviewed. These are the measurement of the direct CP asymmetry
in the B0s->K-\pi+ decay performed by CDF and the measurement of \Delta\Gamma_s
and \phi_s performed by D0 in the B0s->J/\psi\phi decay.


title:
Upper and lower bounds for the large polaron dispersion in $D=1,2,3$
  dimensions

abstract:
  Numerical results for the polaron dispersion are presented for an arbitrary
number of space dimensions. Upper and lower bounds are calculated for the
dispersion curves. They are rather close to each other in the cases of small
electron-phonon couplings usual for real polar materials. To describe the
dispersion in other materials, we suggest a simple fitting formula which can be
applied at intermediate values of the Fr\"ohlich electron-phonon coupling
constant. Its validity is approved by the comparison with direct calculations
and previously obtained results. This makes our results not only reliable and
highly accurate but also easy reproducible.


title:
ASTE Submillimeter Observations of a Young Stellar Object Condensation
  in Cederblad 110

abstract:
  We present results of submillimeter observations of a low-mass young stellar
objects (YSOs) condensation in the Cederblad 110 region of the Chamaeleon I
dark cloud with Atacama Submillimeter Telescope Experiment. Our HCO+(J=4-3) map
reveals a dense molecular gas with an extent of ~ 0.1 pc, which is a complex of
two envelopes associated with class I sources Ced110 IRS4 and IRS11 and a very
young object Cha-MMS1. The other two class I sources in this region, IRS6 and
NIR89, are located outside the clump and have no extended HCO+ emission. HCO+
abundance is calculated to be 2.6 x 10^{-10} for MMS1 and 3.4 x 10^{-9} for
IRS4, which are comparable to the reported value for other young sources.
Bipolar outflows from IRS4 and IRS6 are detected in our 12CO(J=3-2) map. The
outflow from IRS4 seems to collide with Cha-MMS1. The outflow has enough
momentum to affect gas motion in MMS1, although no sign has been detected to
indicate that a triggered star formation has occurred.


title:
Fluctuating initial conditions in heavy-ion collisions from the Glauber
  approach

abstract:
  In the framework of the Glauber approach we analyze the shape parameters of
the early-formed system and their event-by-event fluctuations. We test a
variety of models: the conventional wounded nucleon model, a model admixing
binary collisions to the wounded nucleons, a model with hot spots, as well as
the hot-spot model where the deposition of energy occurs with a superimposed
probability distribution. We look in detail at the so-called participant
multipole moments, obtained by an averaging procedure where in each event the
system is translated to its center of mass and aligned with the major principal
axis of the ellipse of inertia. Quantitative comparisons indicate substantial
relative effects for eccentricity in variants of Glauber models. On the other
hand, the dependence of the scaled standard deviation of the participant
eccentricity on the chosen model is weak. For all models the values range from
about 0.5 for the central collisions to about 0.3-0.4 for peripheral
collisions, both for the gold-gold and copper-copper collisions. They are
dominated by statistics and change only by 10-15% from model to model. We
provide an approximate analytic expansion for the multipole moments and their
fluctuations given in terms of the fixed-axes moments. For central collisions
and in the absence of correlations it gives the simple formula for the scaled
standard deviation of the participant eccentricity: sqrt(4/pi-1). Similarly, we
obtain expansions for the radial profiles of the multipole distributions. We
investigate the relevance of the shape-fluctuation effects for jet quenching
and find them important only for very central events. Finally, we argue how
smooth hydro leads to the known result v_4 ~ v_2^2, and further to the
prediction Delta v_4/v_4 = 2 Delta v_2/v_2.


title: A mixed problem for the infinity laplacian via Tug-of-War games

abstract:
  In this paper we prove that a function $ u\in\mathcal{C}(\bar{\Omega})$ is
the continuous value of the Tug-of-War game described in \cite{PSSW} if and
only if it is the unique viscosity solution to the infinity laplacian with
mixed boundary conditions
  {-\Delta_{\infty}u(x)=0\quad & \text{in} \Omega,
  \frac{\partial u}{\partial n}(x)=0\quad & \text{on} \Gamma_N, u(x)=F(x)\quad
& \text{on} \Gamma_D. By using the results in \cite{PSSW}, it follows that this
viscous PDE problem has a unique solution, which is the unique {\it absolutely
minimizing Lipschitz extension} to the whole $\bar{\Omega}$ (in the sense of
\cite{Aronsson} and \cite{PSSW}) of the boundary data $ F:\Gamma_D\to\R $.


title: Theory of the Siegel Modular Variety

abstract:
  In this paper, we discuss the theory of the Siegel modular variety in the
aspects of arithmetic and geometry. This article covers the theory of Siegel
modular forms, the Hecke theory, a lifting of elliptic cusp forms, geometric
properties of the Siegel modular variety, (hypothetical) motives attached to
Siegel modular forms and a cohomology of the Siegel modular variety.


title:
Exploring the Di-Photon Decay of a Light Higgs Boson in the MSSM With
  Explicit CP Violation

abstract:
  The di-photon decay channel of the lightest Higgs boson is considerd as a
probe to explore CP violation in the Minimal Supersymmetric Standard Model
(MSSM). The scalar/pseudo-scalar mixing is considered along with CP violation
entering through the Higgs-sfermion-sfermion couplings, with and without light
sparticles. The impact of a light stop on the decay width and Branching Ratio
(BR) is established through a detailed study of the amplitude of the process H1
--> gamma.gamma. The other sparticles have little influence even when they are
light. With a suitable combination of other MSSM parameters, a light stop can
change the BR by more than 50 % with a CP-violating phase phi_mu ~ 90 deg.,
while the change is almost nil with a heavy stop.


title:
Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical
  Excitation

abstract:
  We use femtosecond optical pulses to induce, control and monitor
magnetization precession in ferromagnetic Ga0.965Mn0.035As. At temperatures
below ~40 K we observe coherent oscillations of the local Mn spins, triggered
by an ultrafast photoinduced reorientation of the in-plane easy axis. The
amplitude saturation of the oscillations above a certain pump intensity
indicates that the easy axis remains unchanged above ~TC/2. We find that the
observed magnetization precession damping (Gilbert damping) is strongly
dependent on pump laser intensity, but largely independent on ambient
temperature. We provide a physical interpretation of the observed light-induced
collective Mn-spin relaxation and precession.


title:
Characteristic Time and Maximum Mixedness: Single Mode Gaussian States
  in Dissipative Channels

abstract:
  We derive an upper limit for the mixedness of single bosonic mode gaussian
states propagating in dissipative channels. It is a function of the initial
squeezing and temperature of the channel only. Moreover the time at which von
Neumann's entropy reaches its maximum value coincides with that of complete
loss of coherence, thus defining a quantum-classical transition.


title:
On the principle of relativity and electrostatics in a flat spacetime
  with a compact spatial dimension

abstract:
  We study a flat spacetime with a compact spatial dimension and dispute the
claim of Bansal, Laing, and Sriharan that a local experiment can determine
whether or not an inertial observer is "privileged" in this spacetime.


title: Drift and Diffusion of Spins Generated by the Spin Hall Effect

abstract:
  Electrically generated spin accumulation due to the spin Hall effect is
imaged in n-GaAs channels using Kerr rotation microscopy, focusing on its
spatial distribution and time-averaged behavior in a magnetic field.
Spatially-resolved imaging reveals that spin accumulation observed in
transverse arms develops due to longitudinal drift of spin polarization
produced at the sample boundaries. One- and two-dimensional drift-diffusion
modeling is used to explain these features, providing a more complete
understanding of observations of spin accumulation and the spin Hall effect.


title: Mixing-induced global modes in open active flow

abstract:
  We describe how a convectively unstable active field in an open flow
configuration becomes absolutely unstable due to local mixing. A representation
of the mixing region as those with locally enhanced effective diffusion allows
us to find the linear transition point to unstable global mode analytically. We
derive the critical exponent characterizing weakly nonlinear regimes beyond
instability and compare it with numerical simulations of a full two-dimensional
flow problem.


title:
Boltzmann equation for dissipative gases in homogeneous states with
  nonlinear friction

abstract:
  Combining analytical and numerical methods, we study within the framework of
the homogeneous non-linear Boltzmann equation, a broad class of models relevant
for the dynamics of dissipative fluids, including granular gases. We use the
new method presented in a previous paper [J. Stat. Phys. 124, 549 (2006)] and
extend our results to a different heating mechanism, namely a deterministic
non-linear friction force. We derive analytically the high energy tail of the
velocity distribution and compare the theoretical predictions with high
precision numerical simulations. Stretched exponential forms are obtained when
the non-equilibrium steady state is stable. We derive sub-leading corrections
and emphasize their relevance. In marginal stability cases, power-law behaviors
arise, with exponents obtained as the roots of transcendental equations. We
also consider some simple BGK (Bhatnagar, Gross, Krook) models, driven by
similar heating devices, to test the robustness of our predictions.


title: Fermi pockets and correlation effects in underdoped YBa2Cu3O6.5

abstract:
  The detection of quantum oscillations in the electrical resistivity of
YBa2Cu3O6.5 provides direct evidence for the existence of Fermi surface pockets
in an underdoped cuprate. We present a theoretical study of the electronic
structure of YBa2Cu3O7-d (YBCO) aiming at establishing the nature of these
Fermi pockets, i.e. CuO2 plane versus CuO chain or BaO. We argue that electron
correlation effects, such as orbital-dependent band distortions and highly
anisotropic self-energy corrections, must be taken into account in order to
properly interpret the quantum oscillation experiments.


title:
On the Wilsonian renormalization group equation for nuclear current
  operators

abstract:
  We present the solution to the recently derived Wilsonian renormalization
group (RG) equation for nuclear current operators. In order to eliminate the
present ambiguity in the RG equation itself, we introduce a new condition
specifying the cutoff independence of the five point Green function
corresponding to the two-body propagator with current operator insertion. The
resulting effective current operator is then shown to obey a modified
Ward-Takahashi identity which differs from the usual one, but that nevertheless
leads to current conservation.


title:
The minimal principals of Hermitian matrices and the negativity of
  bipartite of qubit states

abstract:
  Quantum entanglement is an enigmatic and powerful property that has attracted
much attention due to its usefulness in new ways of communications, like
quantum teleportation and quantum key distribution. Much effort has been done
to quantify entanglement. Indeed, there exist some well-established
separability criterion and analytical formulas for the entanglement of
bipartite systems. In some of these, the crucial elements are the eigenvalues
of the partial transpose of the density matrix. In this paper, we show that one
can also have information about the entanglement of bipartite state, in C2xC2,
looking at the minimal principals of the partial transpose.


title: Diagonal fibrations are pointwise fibrations

abstract:
  On the category of bisimplicial sets there are different Quillen closed model
structures associated to various definitions of fibrations. In one of them,
which is due to Bousfield and Kan and that consists of seeing a bisimplicial
set as a simplicial object in the category of simplicial sets, fibrations are
those bisimplicial set maps such that each of the induced simplicial set maps
is a Kan fibration, that is, the pointwise fibrations. In another of them,
introduced by Moerdijk, a bisimplicial map is a fibration if it induces a Kan
fibration of associated diagonal simplicial sets, that is, the diagonal
fibrations. In this note, we prove that every diagonal fibration is a pointwise
fibration.


title: Symmetry breaking by the sea of Dirac-Landau levels in graphene

abstract:
  The quantum Hall states of graphene have a filled Dirac sea of Landau levels.
The short ranged SU(4) symmetry breaking interactions can induce a staggered
polarization of the sea of Dirac-Landau levels. We study this effect in the
extended Hubbard model on a honeycomb lattice using mean field variational
wavefunctions. We find a valley symmetry broken, anti-ferromagnetic spin
ordered phase at $\nu=\pm 1$ when the on-site interaction is dominant. Our mean
field solution is consistent with the recently reported experimental results of
Z. Jiang et. al.\cite{jiang}


title: Riesz integral representation theory

abstract:
  We present a Riesz integral representation theory in which functions,
operators and measures take values in uniform commutative monoids (a
commutative monoid with a uniformity making the binary operation of the monoid
uniformly continuous). It describes the operators to which the theory can be
applied and the finitely-additive measures they generate. Operators satisfying
the conditions will be called ``Riesz integrals''. Given an underlying ``Riesz
system'', it is shown that every Riesz integral generates a certain kind of
finitely additive measure called here a ``Riesz measure''. The correspondence
between Riesz integrals and Riesz measures is a bijection.
  A straightforward calculation shows that if an operator has such a
representation, then it must have the Hammerstein property. For topological
vector spaces, the theory yields necessary and sufficient conditions for
operators with the Hammerstein property to be Riesz integrals. We note that
uniform commutative monoids arise naturally when considering set-valued
functions, and that the axioms of a Riesz system rule out certain spaces of
infinitely differentiable functions.


title: Two Gaps Make a High Temperature Superconductor?

abstract:
  One of the keys to the high-temperature superconductivity puzzle is the
identification of the energy scales associated with the emergence of a coherent
condensate of superconducting electron pairs. These might provide a measure of
the pairing strength and of the coherence of the superfluid, and ultimately
reveal the nature of the elusive pairing mechanism in the superconducting
cuprates. To this end, a great deal of effort has been devoted to investigating
the connection between the superconducting transition temperature Tc and the
normal-state pseudogap crossover temperature T*. Here we present a review of a
large body of experimental data that suggests a coexisting two-gap scenario,
i.e. superconducting gap and pseudogap, over the whole superconducting dome.


title:
Heisenberg-limited eavesdropping on the continuous-variable quantum
  cryptographic protocol with no basis switching is impossible

abstract:
  The Gaussian quantum key distribution protocol based on coherent states and
heterodyne detection [Phys. Rev. Lett. 93, 170504 (2004)] has the advantage
that no active random basis switching is needed on the receiver's side. Its
security is, however, not very satisfyingly understood today because the bounds
on the secret key rate that have been derived from Heisenberg relations are not
attained by any known scheme. Here, we address the problem of the optimal
Gaussian individual attack against this protocol, and derive tight upper bounds
on the information accessible to an eavesdropper. The optical scheme achieving
this bound is also exhibited, which concludes the security analysis of this
protocol.


title:
Geodetic precession and frame dragging observed far from massive objects
  and close to a gyroscope

abstract:
  Total precession (geodetic precession and frame dragging) depends on the
velocity of each source of gravitation, which means that it depends on the
choice of the coordinate system. We consider the latter as an anomaly
specifically in the Gravity Probe B experiment, we investigated it and solved
this anomaly. Thus, we proved that if our present expression for the geodetic
precession is correct, then the frame dragging should be 25% less than its
predicted value.


title:
Decoupling of Heavy Kaluza-Klein Modes In Models With Five-Dimensional
  Scalar Fields

abstract:
  We investigate the decoupling of heavy Kaluza-Klein modes in $\phi^{4}$
theory and scalar QED with space-time topology $\mathbb{R}^{3,1} \times S^{1}$.
We calculate the effective action due to integrating out heavy KK modes. We
construct generalized RGE's for the couplings with respect to the
compactification scale $M$. With the solutions to the RGE's we find the
$M$-scale dependence of the effective theory due to higher dimensional quantum
effects. We find that the heavy modes decouple in $\phi^{4}$ theory, but do not
decouple in scalar QED. This is due to the zero mode of the 5-th component
$A_{5}$ of the 5-d gauge field. Because $A_{5}$ is a scalar under 4-d Lorentz
transformations, there is no gauge symmetry protecting it from getting mass and
$A_{5}^{4}$ interaction terms after loop corrections. In light of these
unpleasant features, we explore $S^{1}/\mathbb{Z}_{2}$ compactifications, which
eliminate $A_{5}$, allowing for the heavy modes to decouple at low energies. We
also explore the possibility of decoupling by including higher dimensional
operators. It is found that this is possible, but a high degree of fine tuning
is required.


title: Measuring eccentricity in binary black-hole initial data

abstract:
  Initial data for evolving black-hole binaries can be constructed via many
techniques, and can represent a wide range of physical scenarios. However,
because of the way that different schemes parameterize the physical aspects of
a configuration, it is not alway clear what a given set of initial data
actually represents. This is especially important for quasiequilibrium data
constructed using the conformal thin-sandwich approach. Most initial-data
studies have focused on identifying data sets that represent binaries in
quasi-circular orbits. In this paper, we consider initial-data sets
representing equal-mass black holes binaries in eccentric orbits. We will show
that effective-potential techniques can be used to calibrate initial data for
black-hole binaries in eccentric orbits. We will also examine several different
approaches, including post-Newtonian diagnostics, for measuring the
eccentricity of an orbit. Finally, we propose the use of the ``Komar-mass
difference'' as a useful, invariant means of parameterizing the eccentricity of
relativistic orbits.


title:
Dyakonov-Tamm wave at the planar interface of a chiral sculptured thin
  film and an isotropic dielectric material

abstract:
  Surface waves, named here as Dyakonov-Tamm waves, can exist at the planar
interface of an isotropic dielectric material and a chiral sculptured thin film
(STF). Due to the periodic nonhomogeneity of a chiral STF, the range of the
refractive index of the isotropic material is smaller but the range of the
propagation direction in the interface plane is much larger, in comparison to
those for the existence of Dyakonov waves at the planar interface of an
isotropic dielectric material and a columnar thin film.


title: On the Ring of Integer-valued Quasi-polynomials

abstract:
  The paper studies some properties of the ring of integer-valued
quasi-polynomials. On this ring, theory of generalized Euclidean division and
generalized GCD are presented. Applications to finite simple continued fraction
expansion and Smith normal form of integral matrices with integer parameters
are also given.


title: A low CMB variance in the WMAP data

abstract:
  We have estimated the CMB variance from the three-year WMAP data, finding a
value which is significantly lower than the one expected from Gaussian
simulations using the WMAP best-fit cosmological model, at a significance level
of 98.7 per cent. This result is even more prominent if we consider only the
north ecliptic hemisphere (99.8 per cent). Different analyses have been
performed in order to identify a possible origin for this anomaly. In
particular we have studied the behaviour of single radiometers and single year
data as well as the effect of residual foregrounds and 1/f noise, finding that
none of these possibilities can explain the low value of the variance. We have
also tested the effect of varying the cosmological parameters, finding that the
estimated CMB variance tends to favour higher values of $n_s$ than the one of
the WMAP best-fit model. In addition, we have also tested the consistency
between the estimated CMB variance and the actual measured CMB power spectrum
of the WMAP data, finding a strong discrepancy. A possible interpretation of
this result could be a deviation from Gaussianity and/or isotropy of the CMB.


title: Heterotic Kahler/non-Kahler Transitions

abstract:
  We show how two topologically distinct spaces - the Kahler K3 x T^2 and the
non-Kahler T^2 bundle over K3 - can be smoothly connected in heterotic string
theory. The transition occurs when the base K3 is deformed to the T^4/Z_2
orbifold limit. The orbifold theory can be mapped via duality to M-theory on K3
x K3 where the transition corresponds to an exchange of the two K3's.


title: Soft modes near the buckling transition of icosahedral shells

abstract:
  Icosahedral shells undergo a buckling transition as the ratio of Young's
modulus to bending stiffness increases. Strong bending stiffness favors smooth,
nearly spherical shapes, while weak bending stiffness leads to a sharply
faceted icosahedral shape. Based on the phonon spectrum of a simplified
mass-and-spring model of the shell, we interpret the transition from smooth to
faceted as a soft-mode transition. In contrast to the case of a disclinated
planar network where the transition is sharply defined, the mean curvature of
the sphere smooths the transitition. We define elastic susceptibilities as the
response to forces applied at vertices, edges and faces of an icosahedron. At
the soft-mode transition the vertex susceptibility is the largest, but as the
shell becomes more faceted the edge and face susceptibilities greatly exceed
the vertex susceptibility. Limiting behaviors of the susceptibilities are
analyzed and related to the ridge-scaling behavior of elastic sheets. Our
results apply to virus capsids, liposomes with crystalline order and other
shell-like structures with icosahedral symmetry.


title:
Global perspectives on the energy landscapes of liquids, supercooled
  liquids, and glassy systems: The potential energy landscape ensemble

abstract:
  In principle, all of the dynamical complexities of many-body systems are
encapsulated in the potential energy landscapes on which the atoms move - an
observation that suggests that the essentials of the dynamics ought to be
determined by the geometry of those landscapes. But what are the principal
geometric features that control the long-time dynamics? We suggest that the key
lies not in the local minima and saddles of the landscape, but in a more global
property of the surface: its accessible pathways. In order to make this notion
more precise we introduce two ideas: (1) a switch to a new ensemble that
removes the concept of potential barriers from the problem, and (2) a way of
finding optimum pathways within this new ensemble. The potential energy
landscape ensemble, which we describe in the current paper, regards the maximum
accessible potential energy, rather than the temperature, as a control
variable. We show here that while this approach is thermodynamically equivalent
to the canonical ensemble, it not only sidesteps the idea of barriers, it
allows us to be quantitative about the connectivity of a landscape. We
illustrate these ideas with calculations on a simple atomic liquid and on the
Kob-Andersen model of a glass-forming liquid, showing, in the process, that the
landscape of the Kob-Anderson model appears to have a connectivity transition
at the landscape energy associated with its mode-coupling transition. We turn
to the problem of finding the most efficient pathways through potential energy
landscapes in our companion paper.


title: Simple Picture for Neutrino Flavor Transformation in Supernovae

abstract:
  We can understand many recently-discovered features of flavor evolution in
dense, self-coupled supernova neutrino and antineutrino systems with a simple,
physical scheme consisting of two quasi-static solutions. One solution closely
resembles the conventional, adiabatic single neutrino
Mikheyev-Smirnov-Wolfenstein (MSW) mechanism, in that neutrinos and
antineutrinos remain in mass eigenstates as they evolve in flavor space. The
other solution is analogous to the regular precession of a gyroscopic pendulum
in flavor space, and has been discussed extensively in recent works. Results of
recent numerical studies are best explained with combinations of these
solutions in the following general scenario: (1) Near the neutrino sphere, the
MSW-like many-body solution obtains. (2) Depending on neutrino vacuum mixing
parameters, luminosities, energy spectra, and the matter density profile,
collective flavor transformation in the nutation mode develops and drives
neutrinos away from the MSW-like evolution and toward regular precession. (3)
Neutrino and antineutrino flavors roughly evolve according to the regular
precession solution until neutrino densities are low. In the late stage of the
precession solution, a stepwise swapping develops in the energy spectra of
$\nu_e$ and $\nu_\mu/\nu_\tau$. We also discuss some subtle points regards
adiabaticity in flavor transformation in dense neutrino systems.


title: Cosmic Rays and Global Warming

abstract:
  It has been claimed by others that observed temporal correlations of
terrestrial cloud cover with `the cosmic ray intensity' are causal. The
possibility arises, therefore, of a connection between cosmic rays and Global
Warming. If true, the implications would be very great. We have examined this
claim to look for evidence to corroborate it. So far we have not found any and
so our tentative conclusions are to doubt it. Such correlations as appear are
more likely to be due to the small variations in solar irradiance, which, of
course, correlate with cosmic rays. We estimate that less than 15% of the
11-year cycle warming variations are due to cosmic rays and less than 2% of the
warming over the last 35 years is due to this cause.

categories: astro-ph physics.ao-ph physics.geo-ph physics.soc-ph


title:
Global perspectives on the energy landscapes of liquids, supercooled
  liquids, and glassy systems: Geodesic pathways through the potential energy
  landscape

abstract:
  How useful it is to think about the potential energy landscape of a complex
many-body system depends in large measure on how direct the connection is to
the system's dynamics. In this paper we show that, within what we call the
potential energy landscape ensemble, it is possible to make direct connections
between the geometry of the landscape and the long-time dynamical behaviors of
systems such as supercooled liquids. We show, in particular, that the onset of
slow dynamics in such systems is governed directly by the lengths of their
geodesics - the shortest paths through their landscapes within the special
ensemble. The more convoluted and labyrinthine these geodesics are, the slower
that dynamics is. Geodesics in the landscape ensemble have sufficiently
well-defined characteristics that is straightforward to search for them
numerically, a point we illustrate by computing the geodesic lengths for an
ordinary atomic liquid and a binary glass-forming atomic mixture. We find that
the temperature dependence of the diffusion constants of these systems,
including the precipitous drop as the glass-forming system approaches its
mode-coupling transition, is predicted quantitatively by the growth of the
geodesic path lengths.


title: Schwarzian Derivatives and Uniform Local Univalence

abstract:
  Quantitative estimates are obtained for the (finite) valence of functions
analytic in the unit disk with Schwarzian derivative that is bounded or of slow
growth. A harmonic mapping is shown to be uniformly locally univalent with
respect to the hyperbolic metric if and only if it has finite Schwarzian norm,
thus generalizing a result of B. Schwarz for analytic functions. A numerical
bound is obtained for the Schwarzian norms of univalent harmonic mappings.


title:
Accelerated Projected Gradient Method for Linear Inverse Problems with
  Sparsity Constraints

abstract:
  Regularization of ill-posed linear inverse problems via $\ell_1$ penalization
has been proposed for cases where the solution is known to be (almost) sparse.
One way to obtain the minimizer of such an $\ell_1$ penalized functional is via
an iterative soft-thresholding algorithm. We propose an alternative
implementation to $\ell_1$-constraints, using a gradient method, with
projection on $\ell_1$-balls. The corresponding algorithm uses again iterative
soft-thresholding, now with a variable thresholding parameter. We also propose
accelerated versions of this iterative method, using ingredients of the
(linear) steepest descent method. We prove convergence in norm for one of these
projected gradient methods, without and with acceleration.


title:
Unison as a Self-Stabilizing Wave Stream Algorithm in Asynchronous
  Anonymous Networks

abstract:
  How to pass from local to global scales in anonymous networks? How to
organize a selfstabilizing propagation of information with feedback. From the
Angluin impossibility results, we cannot elect a leader in a general anonymous
network. Thus, it is impossible to build a rooted spanning tree. Many problems
can only be solved by probabilistic methods. In this paper we show how to use
Unison to design a self-stabilizing barrier synchronization in an anonymous
network. We show that the commuication structure of this barrier
synchronization designs a self-stabilizing wave-stream, or pipelining wave, in
anonymous networks. We introduce two variants of Wave: the strong waves and the
wavelets. A strong wave can be used to solve the idempotent r-operator
parametrized computation problem. A wavelet deals with k-distance computation.
We show how to use Unison to design a self-stabilizing wave stream, a
self-stabilizing strong wave stream and a self-stabilizing wavelet stream.


title: A Metric on Shape Space with Explicit Geodesics

abstract:
  This paper studies a specific metric on plane curves that has the property of
being isometric to classical manifold (sphere, complex projective, Stiefel,
Grassmann) modulo change of parametrization, each of these classical manifolds
being associated to specific qualifications of the space of curves
(closed-open, modulo rotation etc...) Using these isometries, we are able to
explicitely describe the geodesics, first in the parametric case, then by
modding out the paremetrization and considering horizontal vectors. We also
compute the sectional curvature for these spaces, and show, in particular, that
the space of closed curves modulo rotation and change of parameter has positive
curvature. Experimental results that explicitly compute minimizing geodesics
between two closed curves are finally provided


title:
Morphological influence on surface--wave propagation at the planar
  interface of a metal film and a columnar thin film

abstract:
  The selection of a higher vapor deposition angle when growing a columnar thin
film (CTF) leads to surface-wave propagation at a planar metal-CTF interface
with phase velocity of lower magnitude and shorter propagation range.
Acordingly, a higher angle of plane-wave incidence is required to excite that
surface wave in a modified Kretschmann configuration.


title: Searching for Gravitational-Wave Bursts with LIGO

abstract:
  We present recent results from searches by the LIGO Science Collaboration for
bursts of gravitational-wave radiation, as well as the status of other ongoing
searches. These include directed searches for bursts associated with observed
sources (gamma-ray bursts, soft gamma repeaters) and untriggered searches for
bursts from unknown sources. We also present the status of some newer
investigations, such as coherent network methods. We show methods for
interpreting our search results in terms of astrophysical source distributions
that improve their accessibility to the wider community.


title:
Silicon beamsplitter for Fourier transform spectroscopy at far infrared
  frequencies

abstract:
  We report the performance of a silicon wafer beamsplitter for use for low
$\Delta\nu>0.3 cm^{-1}$ resolution Fourier transform spectroscopy at far
infrared frequencies. We characterize the Si beamsplitter by comparing
throughput spectra measured with it to those measured with the standard Mylar
beamsplitters commonly used in that range. We find that the throughput of the
silicon beamsplitter is substantially greater than that of the Mylar
beamsplitters over most of the IR spectrum, and that they are comparable in
some limited ranges. The 2 mm silicon beamsplitter has an etalon spacing of
about 0.7 cm^{-1}, which interferes with its use for $0.1 cm^{-1}<\Delta\nu <
0.3cm^{-1}$. The average efficiency of the Si beamsplitter is 0.37 compared
with a maximum efficiency of 0.35 for Mylar. The Si is particularly more
efficient in the 100 to 400 cm^{-1} range because of absorption in Mylar.


title:
Global General Relativistic MHD Simulation of a Tilted Black-Hole
  Accretion Disk

abstract:
  This paper presents a continuation of our efforts to numerically study
accretion disks that are misaligned (tilted) with respect to the rotation axis
of a Kerr black hole. Here we present results of a global numerical simulation
which fully incorporates the effects of the black hole spacetime as well as
magnetorotational turbulence that is the primary source of angular momentum
transport in the flow. This simulation shows dramatic differences from
comparable simulations of untilted disks. Accretion onto the hole occurs
predominantly through two opposing plunging streams that start from high
latitudes with respect to both the black-hole and disk midplanes. This is due
to the aspherical nature of the gravitational spacetime around the rotating
black hole. These plunging streams start from a larger radius than would be
expected for an untilted disk. In this regard the tilted black hole effectively
acts like an untilted black hole of lesser spin. Throughout the duration of the
simulation, the main body of the disk remains tilted with respect to the
symmetry plane of the black hole; thus there is no indication of a
Bardeen-Petterson effect in the disk at large. The torque of the black hole
instead principally causes a global precession of the main disk body. In this
simulation the precession has a frequency of $3 (M_\odot/M)$ Hz, a value
consistent with many observed low-frequency quasi-periodic oscillations.
However, this value is strongly dependent on the size of the disk, so this
frequency may be expected to vary over a large range.


title:
Erratum: Assessment of uncertainties in QRPA $0\nu\beta\beta$-decay
  nuclear matrix elements [Nucl. Phys. A 766, 107 (2006)]

abstract: This is an erratum to our previously published paper.


title: Moments from their very truncations

abstract:
  It is known that positive definiteness is not enough for the multidimensional
moment problem to be solved. We would like throw in to the garden of existing
in this matter so far results one more, a result which takes into
considerations the utmost possible truncations.


title: Smooth models of quiver moduli

abstract:
  For any moduli space of stable representations of quivers, certain smooth
varieties, compactifying projective space fibrations over the moduli space, are
constructed. The boundary of this compactification is analyzed. Explicit
formulas for the Betti numbers of the smooth models are derived. In the case of
moduli of simple representations, explicit cell decompositions of the smooth
models are constructed.


title:
Sonic booms and diffusion wakes generated by a heavy quark in thermal
  AdS/CFT

abstract:
  We evaluate the Poynting vector generated by a heavy quark moving through a
thermal state of N=4 gauge theory using AdS/CFT. A significant diffusion wake
is observed as well as a Mach cone. We discuss the ratio of the energy going
into sound modes to the energy coming in from the wake.


title:
Reducibility of the polynomial representation of the degenerate double
  affine Hecke algebra

abstract:
  In this note we determine the values of parameters c for which the polynomial
representation of the degenerate double affine Hecke algebra (DAHA), i.e. the
trigonometric Cherednik algebra, is reducible. Namely, we show that c is a
reducibility point for the polynomial representation of the trigonometric
Cherednik algebra for a root system R if and only if it is a reducibility point
for the rational Cherednik algebra for the Weyl group of some root subsystem R'
of R of the same rank; such subsystems for any R are given by the well known
Borel-de Siebenthal algorithm. This result has been proved by Cherednik using a
case-by-case method.


title: Constraints on the extra dimension from KK gravitino decay

abstract:
  We study the consequences of the gravitino decay into dark matter. We suppose
that the lightest neutralino is the main component of dark matter. In our
framework gravitino is heavy enough to decay before Big Bang Nucleosynthesis
starts. We consider a model coming from a five dimensional supergravity
compactified on $S^1/Z_2$ with gravity in the bulk and matter localized on
tensionless branes at the orbifold fixed points. We require that the dark
matter, which is produced thermally and in the decay of Kaluza-Klein modes of
gravitino, has an abundance compatible with observation. We deduce from our
model that there are curves of constraints between the size of the
extra-dimension and the reheating temperature of the universe after inflation.
This talk is based on hep-ph/0702183 to be published in \PRD.


title:
Exotic phase diagram of a cluster charging model of bosons on the kagome
  lattice

abstract:
  We study a model of hard-core bosons on the kagome lattice with short-range
hopping ($t$) and repulsive interactions ($V$). This model directly maps on to
an easy-axis $S=1/2$ XXZ model on the kagome lattice and is also related, at
large $V/t$, to a quantum dimer model on the triangular lattice. Using quantum
Monte Carlo (QMC) numerics, we map out the phase diagram of this model at
half-filling. At T=0, we show that this model exhibits a superfluid phase at
small $V/t$ and an insulating phase at large $V/t$, separated by a continuous
quantum phase transition at $V_c/t \approx 19.8$. The insulating phase at T=0
appears to have no conventional broken symmetries, and is thus a uniform Mott
insulator (a `spin liquid' in magnetic language). We characterize this
insulating phase as a uniform $Z_2$ fractionalized insulator from the
topological order in the ground state and estimate its vison gap. Consistent
with this identification, there is no apparent thermal phase transition upon
heating the insulator. The insulating phase instead smoothly crosses over into
the high temperature paramagnet via an intermediate cooperative paramagnetic
regime. We also study the superfluid-to-normal thermal transition for $V <
V_c$. We find that this is a Kosterlitz-Thouless transition at small $V/t$ but
changes to a first order transition for $V$ closer to $V_c$. We argue that this
first order thermal transition is consistent with the presence of a nearby
$Z_2$ insulating ground state obtained from the superfluid ground state by
condensing double vortices.


title:
LHC Phenomenology of an Extended Standard Model with a Real Scalar
  Singlet

abstract:
  Gauge singlet extensions of the Standard Model (SM) scalar sector may help
remedy its theoretical and phenomenological shortcomings while solving
outstanding problems in cosmology. Depending on the symmetries of the scalar
potential, such extensions may provide a viable candidate for the observed
relic density of cold dark matter or a strong first order electroweak phase
transition needed for electroweak baryogenesis. Using the simplest extension of
the SM scalar sector with one real singlet field, we analyze the generic
implications of a singlet-extended scalar sector for Higgs boson phenomenology
at the Large Hadron Collider (LHC). We consider two broad scenarios: one in
which the neutral SM Higgs and singlet mix and the other in which no mixing
occurs and the singlet can be a dark matter particle. For the first scenario,
we analyze constraints from electroweak precision observables and their
implications for LHC Higgs phenomenology. For models in which the singlet is
stable, we determine the conditions under which it can yield the observed relic
density, compute the cross sections for direct detection in recoil experiments,
and discuss the corresponding signatures at the LHC.


title:
Interacting Binaries with Eccentric Orbits. Secular Orbital Evolution
  Due To Conservative Mass Transfer

abstract:
  We investigate the secular evolution of the orbital semi-major axis and
eccentricity due to mass transfer in eccentric binaries, assuming conservation
of total system mass and orbital angular momentum. Assuming a delta function
mass transfer rate centered at periastron, we find rates of secular change of
the orbital semi-major axis and eccentricity which are linearly proportional to
the magnitude of the mass transfer rate at periastron. The rates can be
positive as well as negative, so that the semi-major axis and eccentricity can
increase as well as decrease in time. Adopting a delta-function mass-transfer
rate of $10^{-9} M_\sun {\rm yr}^{-1}$ at periastron yields orbital evolution
timescales ranging from a few Myr to a Hubble time or more, depending on the
binary mass ratio and orbital eccentricity. Comparison with orbital evolution
timescales due to dissipative tides furthermore shows that tides cannot, in all
cases, circularize the orbit rapidly enough to justify the often adopted
assumption of instantaneous circularization at the onset of mass transfer. The
formalism presented can be incorporated in binary evolution and population
synthesis codes to create a self-consistent treatment of mass transfer in
eccentric binaries.


title: Rephasing Invariants of Quark and Lepton Mixing Matrices

abstract:
  Rephasing invariants of quark and lepton mixing matrices are obtained in the
standard model extended by the seesaw mechanism, and in its low-energy
effective theory with the dimension-five Majorana mass operator. We classify
the basic invariants, discuss non-trivial relations between them, and determine
the independent invariants which characterize all the information in the mixing
matrices in a basis-independent way. We also discuss the restrictions on the
allowed ranges for the mixing phases, and on the rephasing invariants, which
follow from a discrete invariance of the Majorana mass matrix.


title: Domain growth morphology in curvature driven two dimensional coarsening

abstract:
  We study the distribution of domain areas, areas enclosed by domain
boundaries (''hulls''), and perimeters for curvature-driven two-dimensional
coarsening, employing a combination of exact analysis and numerical studies,
for various initial conditions. We show that the number of hulls per unit area,
$n_h(A,t) dA$, with enclosed area in the interval $(A,A+dA)$, is described, for
a disordered initial condition, by the scaling function $n_h(A,t) = 2c_h/(A +
\lambda_h t)^2$, where $c_h=1/8\pi\sqrt{3} \approx 0.023$ is a universal
constant and $\lambda_h$ is a material parameter. For a critical initial
condition, the same form is obtained, with the same $\lambda_h$ but with $c_h$
replaced by $c_h/2$. For the distribution of domain areas, we argue that the
corresponding scaling function has, for random initial conditions, the form
$n_d(A,t) = 2c_d (\lambda_d t)^{\tau'-2}/(A + \lambda_d t)^{\tau'}$, where
$c_d=c_h + {\cal O}(c_h^2)$, $\lambda_d=\lambda_h + {\cal O}(c_h)$, and $\tau'
= 187/91 \approx 2.055$. For critical initial conditions, one replaces $c_d$ by
$c_d/2$ (possibly with corrections of ${\cal O}(c_h^2)$) and the exponent is
$\tau = 379/187 \approx 2.027$. These results are extended to describe the
number density of the length of hulls and domain walls surrounding connected
clusters of aligned spins. These predictions are supported by extensive
numerical simulations. We also study numerically the geometric properties of
the boundaries and areas.


title: Cutoff Resolvent Estimates and the Semilinear Schr\"odinger Equation

abstract:
  This paper shows how abstract resolvent estimates imply local smoothing for
solutions to the Schr\"odinger equation. If the resolvent estimate has a loss
when compared to the optimal, non-trapping estimate, there is a corresponding
loss in regularity in the local smoothing estimate. As an application, we apply
well-known techniques to obtain well-posedness results for the semi-linear
Schr\"odinger equation.


title: On Combining Lensing Shear Information from Multiple Filters

abstract:
  We consider the possible gain in the measurement of lensing shear from
imaging data in multiple filters. Galaxy shapes may differ significantly across
filters, so that the same galaxy offers multiple samples of the shear. On the
other extreme, if galaxy shapes are identical in different filters, one can
combine them to improve the signal-to-noise and thus increase the effective
number density of faint, high redshift galaxies. We use the GOODS dataset to
test these scenarios by calculating the covariance matrix of galaxy
ellipticities in four visual filters (B,V,i,z). We find that galaxy shapes are
highly correlated, and estimate the gain in galaxy number density by combining
their shapes.


title:
On the Effects of Dissipative Turbulence on the Narrow Emission-Line
  Ratios in Seyfert Galaxies

abstract:
  We present a photoionization model study of the effects of micro-turbulence
and dissipative heating on emission lines for number and column densities,
elemental abundances, and ionizations typical for the narrow emission line
regions (NLRs) of Seyfert galaxies. Earlier studies of NLR spectra generally
found good agreement between the observations and the model predictions for
most strong emission lines, such as [O III] $\lambda$5007, [O II]
$\lambda$3727, [N II] $\lambda$6583, [Ne III] $\lambda$3869, and the H and He
recombination lines. Nevertheless, the strengths of lines from species with
ionization potentials greater than that of He$^{+}$(54.4 eV), e.g. N$^{+4}$ and
Ne$^{+4}$, were often under-predicted. Among the explanations suggested for
these discrepancies were (selectively) enhanced elemental abundances and
contributions from shock heated gas. Interestingly, the NLR lines have widths
of several 100 km s$^{-1}$, well in excess of the thermal broadening. If this
is due to micro-turbulence, and the turbulence dissipates within the
emission-line gas, the gas can be heated in excess of that due to
photoionization. We show that the combined effects of turbulence and
dissipative heating can strongly enhance N V $\lambda$1240 (relative to He II
$\lambda$1640), while the heating alone can boost the strength of [Ne V]
$\lambda$3426. We suggest that this effect is present in the NLR, particularly
within $\sim$ 100 pc of the central engine. Finally, since micro-turbulence
would make clouds robust against instabilities generated during acceleration,
it is not likely to be a coincidence that the radially outflowing emission-line
gas is turbulent.


title: CDF Hot Topics

abstract:
  We present recent CDF results based on approximately 1 fb$^{-1}$ of $p\bar p$
collisions at $\sqrt s = 1.96$ TeV delivered at Fermilab Tevatron. Results
shown include the observation of the $B_s$ oscillation frequency, the first
observation of bottom baryon $\Sigma_b^{(*)\pm}$ states, updates on $B$ hadrons
lifetimes, and searches for rare decays in the $b\to s\mu^+\mu^-$ transition
and in charmless two-body B decays.


title:
Non-Fermi-liquid behavior in nearly ferromagnetic metallic SrIrO3 single
  crystals

abstract:
  We report transport and thermodynamic properties of single-crystal SrIrO3 as
a function of temperature T and applied magnetic field H. We find that SrIrO3
is a non-Fermi-liquid metal near a ferromagnetic instability, as characterized
by the following properties: (1) small ordered moment but no evidence for
long-range order down to 1.7 K; (2) strongly enhanced magnetic susceptibility
that diverges as T or T1/2 at low temperatures, depending on the applied field;
(3) heat capacity C(T,H) ~ -Tlog T that is readily amplified by low applied
fields; (4) a strikingly large Wilson ratio at T< 4K; and (5) a T3/2-dependence
of electrical resistivity over the range 1.7 < T < 120 K. A phase diagram based
on the data implies SrIrO3 is a rare example of a stoichiometric oxide compound
that exhibits non-Fermi-liquid behavior near a quantum critical point (T = 0
and H = 0.23 T).


title: Realization of Levy flights as continuous processes

abstract:
  On the basis of multivariate Langevin processes we present a realization of
Levy flights as a continuous process. For the simple case of a particle moving
under the influence of friction and a velocity dependent stochastic force we
explicitly derive the generalized Langevin equation and the corresponding
generalized Fokker-Planck equation describing Levy flights. Our procedure is
similar to the treatment of the Kramers-Fokker Planck equation in the
Smoluchowski limit. The proposed approach forms a feasible way of tackling Levy
flights in inhomogeneous media or systems with boundaries what is up to now a
challenging problem.


title: An optical surface resonance may render photonic crystals ineffective

abstract:
  In this work we identify and study the presence of extremely intense surface
resonances that frustrate the coupling of photons into a photonic crystal over
crucial energy ranges. The practical utility of photonic crystals demands the
capability to exchange photons with the external medium, therefore, it is
essential to understand the cause of these surface resonances and a route to
their elimination. We demonstrate that by modifying the surface geometry it is
possible to tune the optical response or eliminate the resonances to enable
full exploitation of the photonic crystal.


title:
Measurement of the UHECR spectrum above 10 EeV at the Pierre Auger
  Observatory using showers with zenith angles greater than 60 degrees

abstract:
  We report a measurement of the cosmic ray energy spectrum obtained using the
inclined events detected with the Pierre Auger Observatory. Showers with zenith
angles between 60 and 80 degrees recorded in the period between 1 January 2004
and 28 February 2007 are analysed. Showers are first reconstructed in arrival
direction and then fitted to density maps of the muon numbers obtained from 10
EeV simulated proton showers for different arrival directions, in order to
obtain the core position and an overall normalisation factor N19 which is used
as an energy estimator. The parameter N19 is shown to be correlated with the
shower energy measured with the fluorescence technique for a sub-sample of good
quality hybrid showers. This correlation, measured with hybrid events, is then
used to determine the energy of all the showers.


title: Theory of Finite or Infinite Trees Revisited

abstract:
  We present in this paper a first-order axiomatization of an extended theory
$T$ of finite or infinite trees, built on a signature containing an infinite
set of function symbols and a relation $\fini(t)$ which enables to distinguish
between finite or infinite trees. We show that $T$ has at least one model and
prove its completeness by giving not only a decision procedure, but a full
first-order constraint solver which gives clear and explicit solutions for any
first-order constraint satisfaction problem in $T$. The solver is given in the
form of 16 rewriting rules which transform any first-order constraint $\phi$
into an equivalent disjunction $\phi$ of simple formulas such that $\phi$ is
either the formula $\true$ or the formula $\false$ or a formula having at least
one free variable, being equivalent neither to $\true$ nor to $\false$ and
where the solutions of the free variables are expressed in a clear and explicit
way. The correctness of our rules implies the completeness of $T$. We also
describe an implementation of our algorithm in CHR (Constraint Handling Rules)
and compare the performance with an implementation in C++ and that of a recent
decision procedure for decomposable theories.


title: Conformal coordinates of a constant density star

abstract:
  It is well known that the interior of a constant density spherical star is
conformally flat. In this paper we obtain the coordinate system in which the
conformal flatness of the metric manifests itself. In a similar way, we also
construct such coordinates for Robertson Walker metric.


title:
Disappearance of Squeezed Back-to-Back Correlations - a new signal of
  hadron freeze-out from a supercooled Quark Gluon Plasma

abstract:
  We briefly discuss four different possible types of transitions from quark to
hadronic matter and their characteristic signatures in terms of correlations.
We also highlight the effects arising from mass modification of hadrons in hot
and dense hadronic matter, as well as their quantum statistical consequences:
the appearance of squeezed quantum states and the associated experimental
signatures, i.e., the back-to-back correlations of particle - anti-particle
pairs. We briefly review the theoretical results of these squeezed quanta,
generated by in-medium modified masses, starting from the first indication of
the existence of surprising particle - anti-particle correlations, and ending
by considering the effects of chiral dynamics on these correlation patterns. A
prerequisite for such a signature is the experimental verification that these
theoretically predicted back-to-back correlation of particle anti-particle
pairs are, in fact, observable in high energy heavy ion reactions. Therefore,
the experimental observation of back-to-back correlations in high energy heavy
ion reactions would be a unique signature, proving the existence of in-medium
mass modification of hadronic states. On the other hand, their disappearance at
some threshold centrality or collision energy would indicate that the hadron
formation mechanism would have qualitatively changed: asymptotic hadrons above
such a threshold are not formed from medium modified hadrons anymore, but
rather by new degrees of freedom characterizing the medium. Furthermore, the
disappearance of the squeezed BBC could also serve as a signature of a sudden,
non-equilibrium hadronization scenario from a supercooled quark-gluon plasma
phase.


title: The age grading and the Chen-Ruan cup product

abstract:
  We prove that the obstruction bundle used to define the cup-product in
Chen-Ruan cohomology is determined by the so-called `age grading' or
`degree-shifting numbers'. Indeed, the obstruction bundle can be directly
computed using the age grading. We obtain a Kunneth Theorem for Chen-Ruan
cohomology as a direct consequence of an elementary property of the age
grading, and explain how several other results - including associativity of the
cup-product - can be proved in a similar way.


title: Dynamical structure factor at small q for the XXZ spin-1/2 chain

abstract:
  We combine Bethe Ansatz and field theory methods to study the longitudinal
dynamical structure factor S^{zz}(q,omega) for the anisotropic spin-1/2 chain
in the gapless regime. Using bosonization, we derive a low energy effective
model, including the leading irrelevant operators (band curvature terms) which
account for boson decay processes. The coupling constants of the effective
model for finite anisotropy and finite magnetic field are determined exactly by
comparison with corrections to thermodynamic quantities calculated by Bethe
Ansatz. We show that a good approximation for the shape of the on-shell peak of
S^{zz}(q,omega) in the interacting case is obtained by rescaling the result for
free fermions by certain coefficients extracted from the effective Hamiltonian.
In particular, the width of the on-shell peak is argued to scale like delta
omega_{q} ~ q^2 and this prediction is shown to agree with the width of the
two-particle continuum at finite fields calculated from the Bethe Ansatz
equations. An exception to the q^2 scaling is found at finite field and large
anisotropy parameter (near the isotropic point). We also present the
calculation of the high-frequency tail of S^{zz}(q,\omega) in the region delta
omega_{q}<< omega-vq << J using finite-order perturbation theory in the band
curvature terms. Both the width of the on-shell peak and the high-frequency
tail are compared with S^{zz}(q,omega) calculated by Bethe Ansatz for finite
chains using determinant expressions for the form factors and excellent
agreement is obtained. Finally, the accuracy of the form factors is checked
against the exact first moment sum rule and the static structure factor
calculated by Density Matrix Renormalization Group (DMRG).


title: QCD factorizations in gamma* gamma* --> rho_L^0 rho_L^0

abstract:
  The exclusive reaction of rho meson pair electroproduction in gamma*gamma*
collisions is a nice place to study various dynamics and factorization
properties in the perturbative sector of QCD. At low energy (quarks dominance),
this process can be considered as a way to explore QCD factorizations involving
generalized distribution amplitudes (GDA) and transition distribution
amplitudes (TDA), and, in the Regge limit of QCD (gluons dominance), it seems
to offer a promising probe of the BFKL resummation effects which could be
studied at the next international linear collider (ILC).


title: BF systems on graph cobordisms as topological cosmology

abstract:
  A cosmological model connecting the evolution of universe with a sequence of
topology changes described by a collection of specific graph cobordisms, is
constructed. It is shown that an adequate topological field theory (of BF-type)
can be put into relation to each graph cobordism. The explicit expressions for
transition amplitudes (partition functions) are written in these BF-models and
it is shown that the basic topological invariants of the graph cobordisms
(intersection matrices) play the r{\^o}le of coupling constants between the
formal analogues of electric and magnetic fluxes quantized {\`a} la Dirac, but
with the use of Poicar{\'e}--Lefschetz duality. For a specific graph cobordism,
the diagonal elements and eigenvalues of the intersection matrix reproduce the
hierarchy of dimensionless low-energy coupling constants of the fundamental
interactions acting in the real universe.


title:
Molecular Outflows and a Mid-Infrared Census of the Massive
  Star-Formation Region Associated with IRAS 18507+0121

abstract:
  We have observed the central region of the IR-dark cloud filament associated
with IRAS 18507+0121 at millimeter wavelengths in CO(1-0), 13CO(1-0), and
C18O(1-0) line emission and with the Spitzer Space Telescope at mid-IR
wavelengths. Five massive outflows from two cloud cores were discovered. Three
outflows are centered on or near an Ultracompact HII region (G34.4+0.23) while
the remaining two outflows originate from the millimeter core G34.4+0.23 MM.
Modeling of the SEDs of the mid-IR sources identified 31 young stellar objects
in the filament with a combined stellar mass of ~127 +/- 27 Msun. An additional
22 sources were identified as probable cluster members based on the presence of
strong 24 micron emission. The total star formation efficiency in the G34.4
cloud filament is estimated to be ~7% while the massive and intermediate mass
star formation efficiency in the entire cloud filament is estimated to be
roughly 2%. A comparison of the gravitational binding energy with the outflow
kinetic energy suggests that the compact core containing G34.4+0.23 MM is being
destroyed by its molecular outflows whereas the outflows associated with more
massive core surrounding the G34.4 UC HII region are not likely to totally
disrupt the cloud. Additionally, a qualitative evaluation of the region appears
to suggest that stars in this region may have formed in two stages: first lower
mass stars formed and then, a few Myrs later, the more massive stars began to
form.


title:
Constraints on Extrasolar Planet Populations from VLT NACO/SDI and MMT
  SDI and Direct Adaptive Optics Imaging Surveys: Giant Planets are Rare at
  Large Separations

abstract:
  We examine the implications for the distribution of extrasolar planets based
on the null results from two of the largest direct imaging surveys published to
date. Combining the measured contrast curves from 22 of the stars observed with
the VLT NACO adaptive optics system by Masciadri et al. (2005), and 48 of the
stars observed with the VLT NACO SDI and MMT SDI devices by Biller et al.
(2007) (for a total of 60 unique stars; the median star for our survey is a 30
Myr K2 star at 25 pc), we consider what distributions of planet masses and
semi-major axes can be ruled out by these data, based on Monte Carlo
simulations of planet populations. We can set this upper limit with 95%
confidence: the fraction of stars with planets with semi-major axis from 20 to
100 AU, and mass >4 M_Jup, is 20% or less. Also, with a distribution of planet
mass of dN/dM ~ M^-1.16 between 0.5-13 M_Jup, we can rule out a power-law
distribution for semi-major axis (dN/da ~ a^alpha) with index 0 and upper
cut-off of 18 AU, and index -0.5 with an upper cut-off of 48 AU. For the
distribution suggested by Cumming et al. (2007), a power-law of index -0.61, we
can place an upper limit of 75 AU on the semi-major axis distribution. At the
68% confidence level, these upper limits state that fewer than 8% of stars have
a planet of mass >4 M_Jup between 20 and 100 AU, and a power-law distribution
for semi-major axis with index 0, -0.5, and -0.61 cannot have giant planets
beyond 12, 23, and 29 AU, respectively. In general, we find that even null
results from direct imaging surveys are very powerful in constraining the
distributions of giant planets (0.5-13 M_Jup) at large separations, but more
work needs to be done to close the gap between planets that can be detected by
direct imaging, and those to which the radial velocity method is sensitive.


title: Can 2HDM support fermion-stabilized bubbles of false vacuum?

abstract:
  The Higgs potential of the two-Higgs-doublet model can have several minima
with different properties. We discuss a possibility that a heavy fermion, if
trapped in a microscopic false vacuum bubble, might become light enough to
prevent the bubble from the collapse.


title:
Energy exchange in fast optical soliton collisions as a random cascade
  model

abstract:
  We study the dynamics of a probe soliton propagating in an optical fiber and
exchanging energy in fast collisions with a random sequence of pump solitons.
The energy exchange is induced by Raman scattering or by cubic nonlinear
loss/gain. We show that the equation describing the dynamics of the probe
soliton's amplitude has the same form as the equation for the local space
average of energy dissipation in random cascade models in turbulence. We
characterize the statistics of the probe soliton's amplitude by the \tau_{q}
exponents from multifractal theory and by the Cram\'er function S(x). We find
that the n-th moment of the two-time correlation function and the
bit-error-rate contribution from amplitude decay exhibit power-law behavior as
functions of propagation distance, where the exponents can be expressed in
terms of \tau_{q} or S(x).


title: Power Loss for Inhomogeneous Poisson Processes

abstract:
  In this work, based on a realization of an inhomogeneous Poisson process
whose intensity function depends on a real unknown parameter, we consider a
simple hypothesis against a sequence of close (contiguous) alternatives. Under
certain regularity conditions we obtain the power loss of the score test with
respect to the Neyman-Pearson test. The power loss measures the performance of
a second order efficient test by the help of third order asymptotic properties
of the problem under consideration.


title: A single-photon transistor using nano-scale surface plasmons

abstract:
  It is well known that light quanta (photons) can interact with each other in
nonlinear media, much like massive particles do, but in practice these
interactions are usually very weak. Here we describe a novel approach to
realize strong nonlinear interactions at the single-photon level. Our method
makes use of recently demonstrated efficient coupling between individual
optical emitters and tightly confined, propagating surface plasmon excitations
on conducting nanowires. We show that this system can act as a nonlinear
two-photon switch for incident photons propagating along the nanowire, which
can be coherently controlled using quantum optical techniques. As a novel
application, we discuss how the interaction can be tailored to create a
single-photon transistor, where the presence or absence of a single incident
photon in a ``gate'' field is sufficient to completely control the propagation
of subsequent ``signal'' photons.


title: On the Connection Between Metal Absorbers and Quasar Nebulae

abstract:
  We establish a simple model for the distribution of cold gas around L*
galaxies using a large set of observational constraints on the properties of
strong MgII absorber systems. Our analysis suggests that the halos of L*
galaxies are filled with cool gaseous clouds having sizes of order 1kpc and
densities of ~10^{-2} cm^{-3}. We then investigate the physical effects of
cloud irradiation by a quasar and study the resulting spectral signatures. We
show that quasar activity gives rise to (i) extended narrow-line emission on
~100kpc scales and (ii) an anisotropy in the properties of the absorbing gas
arising from the geometry of the quasar radiation field. Provided that quasars
reside in halos several times more massive than those of L* galaxies, our model
predictions appear to be in agreement with observations of narrow emission-line
nebulae around quasars and the recent detections of ~100kpc cold gaseous
envelopes around those objects, suggesting a common origin for these phenomena.
We discuss the implications of our results for understanding absorption
systems, probing quasar environments at high redshifts, and testing the quasar
unification scheme.


title: Directed Paths in a Wedge

abstract:
  Directed paths have been used extensively in the scientific literature as a
model of a linear polymer. Such paths models in particular the conformational
entropy of a linear polymer and the effects it has on the free energy. These
directed models are simplified versions of the self-avoiding walk, but they do
nevertheless give insight into the phase behaviour of a polymer, and also serve
as a tool to study the effects of conformational degrees of freedom in the
behaviour of a linear polymer. In this paper we examine a directed path model
of a linear polymer in a confining geometry (a wedge). The main focus of our
attention is $c_n$, the number of directed lattice paths of length $n$ steps
which takes steps in the North-East and South-East directions and which is
confined to the wedge $Y=\pm X/p$, where $p$ is an integer. In this paper we
examine the case $p=2$ in detail, and we determine the generating function
using the iterated kernel method. We also examine the asymtotics of $c_n$. In
particular, we show that $$ c_n = [0.67874...]\times 2^{n-1}(1+(-1)^n) +
O((4/3^{3/4})^{n+o(n)}) + o((4/3^{3/4})^n) $$ where we can determine the
constant $0.67874...$ to arbitrary accuracy with little effort.

categories: cond-mat.soft cond-mat.stat-mech math-ph math.CO math.MP


title:
Convergence properties of Donaldson's $T$-iterations on the Riemann
  sphere

abstract:
  In a recent paper Donaldson defines three operators on a space of Hermitian
metrics on a complex projective manifold: $T, T_{\nu}, T_K.$ Iterations of
these operators converge to balanced metrics, and these themselves approximate
constant scalar curvature metrics. In this paper we investigate the convergence
properties of these iterations by examining the case of the Riemann sphere as
well as higher dimensional $\mathbb{CP}^n$.


title: Dynamical and scaling properties of nu=5/2 interferometer

abstract:
  We calculate the non-linear I-V tunneling curves for a two-point-contact
tunneling junction between two edges of the $\nu={5/2}$ non-abelian fractional
quantum Hall state. The non-linear I-V tunneling curves are calculated for both
cases with and without an $e/4$ non-abelian quasiparticle between the two
contacts. We confirm that, within a dynamical edge theory, the presence of the
$e/4$ quasiparticle between the two contacts destroys the interference between
the two tunneling paths. We also calculate how the interference reappears as
the $e/4$ quasiparticle is moved closer to an edge.


title:
Analogue to multiple electromagnetically induced transparency in
  all-optical drop-filter systems

abstract:
  We theoretically study a parallel optical configuration which includes N
periodically coupled whispering-gallery-mode resonators. The model shows an
obvious effect which has a direct analogy with the phenomenon of multiple
electromagnetically induced transparency in quantum systems. The numerical
simulations illuminate that the frequency transparency windows are sharp and
highly transparent. We also briefly discuss the experimental feasibility of the
current scheme in two practical systems, microrings and microdisks.


title: A note on p-adic q-integrals associated with q-Euler numbers

abstract:
  In this we give a detailed proof of fermionic p-adic q-measures on Z_p and we
will treat some interesting formulae related q-extension of Euler numbers and
polynomials.


title:
Spin-liquid model of the sharp resistivity drop in
  $La_{1.85}Ba_{0.125}CuO_4$

abstract:
  We use the phenomenological model proposed in our previous paper [Phys. Rev.
Lett. {\bf 98}, 237001 (2007)] to analyse the magnetic field dependence of the
onset temperature for two-dimensional fluctuating superconductivity $T^{**}
(H)$. We demonstrate that the slope of $T^{**} (H)$ progressively goes down as
$H$ increases, such that the upper critical field progressively increases as
$T$ decreases. The quantitative agreement with the recent measurements of
$T^{**} (H)$ in $La_{1.85}Ba_{0.125}CuO_4$ is achieved for the same parameter
value as was derived in our previous publication from the analysis of the
electron self energy.


title:
Hausdorff Dimension and Hausdorff Measure for Non-integer based
  Cantor-type Sets

abstract:
  We consider digits-deleted sets or Cantor-type sets with $\beta$-expansions.
We calculate the Hausdorff dimension $d$ of these sets and show that $d$ is
continuous with respect to $\beta$. The $d$-dimentional Hausdorff measure of
these sets is finite and positive.


title:
2-Selmer Groups and the Birch-Swinnerton-Dyer Conjecture for the
  Congruent Number Curve

abstract:
  We take an approach toward counting the number of n for which the curves E_n:
y^2=x^3-n^2x have 2-Selmer groups of a given size. This question was also
discussed in a pair of Invent. Math. papers by Roger Heath-Brown. We discuss
the connection between computing the size of these Selmer groups and verifying
cases of the Birch and Swinnerton-Dyer Conjecture. The key ingredient for the
asymptotic formulae is the ``independence'' of the Legendre symbol evaluated at
the prime divisors of an integer with exactly k prime factors.


title:
NMR relaxation and resistivity from rattling phonons in pyrochlore
  superconductors

abstract:
  We calculate the temperature dependence of NMR relaxation rate and electrical
resistivity for coupling to a local, strongly anharmonic phonon mode. We argue
that the two-phonon Raman process is dominating NMR relaxation. Due to the
strong anharmonicity of the phonon an unusual temperature dependence is found
having a low temperature peak and becoming constant towards higher
temperatures. The electrical resistivity is found to vary like T^2 at low
temperatures and following a sqrt{T} behavior at high temperatures. Both
results are in qualitative agreement with recent observations on
beta-pyrochlore oxide superconductors.


title:
Studying possible CP-violating Higgs couplings through top-quark pair
  productions at muon colliders

abstract:
  We study possible anomalous CP-violating Higgs couplings to mu mu-bar and t
t-bar fully model-independent way through top-quark pair productions at muon
colliders. Assuming additional non-standard neutral Higgs bosons, whose
couplings with top-quark and muon are expressed in the most general covariant
form, we carry out analyses of effects which they are expected to produce via
CP-violating asymmetries and also the optimal-observable (OO) procedure under
longitudinal and transverse muon polarizations. We find the measurement of the
asymmetry for longitudinal beam polarization could be useful to catch some
signal of CP violation, and an OO analysis might also be useful if we could
reduce the number of unknown parameters with a help of other experiments and if
the size of the parameters is at least O(1) ~ O(10).


title: Bulge and Halo Kinematics Across the Hubble Sequence

abstract:
  The correlation between the maximum rotational velocity of the disk (v_m) and
the central stellar velocity dispersion of the bulge (sigma) offers insights
into the relationship between the halo and the bulge. We have assembled
integrated H I line widths and central stellar velocity dispersions to study
the v_m-sigma relation for 792 galaxies spanning a broad range of Hubble types.
Contrary to earlier studies based on much smaller samples, we find that the
v_m-sigma relation exhibits significant intrinsic scatter and that its
zeropoint varies systematically with galaxy morphology, bulge-to-disk ratio,
and light concentration, as expected from basic dynamical considerations.
Nucleated but bulgeless late-type spiral galaxies depart significantly from the
v_m-sigma relation. While these results render questionable any attempt to
supplant the bulge with the halo as the fundamental determinant of the central
black hole mass in galaxies, the observed distribution of v_m/sigma, which
depends on both the density profile and kinematic structure of the galaxy,
offers a useful constraint on galaxy formation models. With the aid of a
near-infrared Tully-Fisher relation, we identify a population of otherwise
normal, luminous galaxies that have exceptionally low values of v_m/sigma. We
argue that a significant fraction of the H I gas in these kinematically
anomalous objects is dynamically unrelaxed, having been acquired externally
either through capture from tidal interactions or through cold accretion from
the intergalactic medium.


title: A fast direct solver for network matrices

abstract:
  A fast direct inversion scheme for the large sparse systems of linear
equations resulting from the discretization of elliptic partial differential
equations in two dimensions is given. The scheme is described for the
particular case of a discretization on a uniform square grid, but can be
generalized to more general geometries. For a grid containing $N$ points, the
scheme requires $O(N \log^{2}N)$ arithmetic operations and $O(N \log N)$
storage to compute an approximate inverse. If only a single solve is required,
then the scheme requires only $O(\sqrt{N} \log N)$ storage; the same storage is
sufficient for computing the Dirichlet-to-Neumann operator as well as other
boundary-to-boundary operators. The scheme is illustrated with several
numerical examples. For instance, a matrix of size $10^6 \times 10^6$ is
inverted to seven digits accuracy in four minutes on a 2.8GHz P4 desktop PC.


title: TeV scale partial mirage unification and neutralino dark matter

abstract:
  We study the TeV scale partial mirage unification scenario, where the gluino
and wino masses are degenerate around a TeV scale, but the bino mass is not
degenerate. This scenario has phenomenologically interesting aspects. First,
because of the degeneracy between the gluino and wino masses, this scenario
does not have the little hierarchy problem, that is, the higgisino mass is
around 150 GeV. The lightest superparticle is a mixture of the bino and
higgsino, and can lead to a right amount of thermal relic density as a dark
matter candidate.


title: On Interdependence of the Paleomagnetic Field Characteristics

abstract:
  The behaviour of the geomagnetic field characteristics (mean values of the
paleointensity, amplitude of its variations and reversal frequency) during the
last 170 million years was analyzed. It was found that the mean values of the
paleointensity were in direct relation to amplitude of its variations and in
reverse relation to reversal frequency. The most considerable changes of the
Earth magnetic field characteristics occurred in Early Cretaceous, Middle
Paleogene and Neogene. The analysis of conformity of the reconstructed
characteristics behaviour of a geomagnetic field to an alfa-omega- dynamo model
was made.


title:
Diffuse Gamma-ray Emission from the Galactic Center - A Multiple Energy
  Injection Model

abstract:
  We suggest that the energy source of the observed diffuse gamma-ray emission
from the direction of the Galactic center is the Galactic black hole Sgr A*,
which becomes active when a star is captured at a rate of $\sim 10^{-5} $
yr^{-1}. Subsequently the star is tidally disrupted and its matter is accreted
into the black hole. During the active phase relativistic protons with a
characteristic energy $\sim 6\times 10^{52}$ erg per capture are ejected. Over
90% of these relativistic protons disappear due to proton-proton collisions on
a timescale $\tau_{pp} \sim 10^4$ years in the small central bulge region with
radius $\sim 50$ pc within Sgr A*, where the density is $\ge 10^3$ cm^{-3}. The
gamma-ray intensity, which results from the decay of neutral pions produced by
proton-proton collisions, decreases according to $e^{-t/\tau_{pp}}$, where t is
the time after last stellar capture. Less than 5% of relativistic protons
escaped from the central bulge region can survive and maintain their energy for
>10^7 years due to much lower gas density outside, where the gas density can
drop to $\sim 1$ cm$^{-3}$. They can diffuse to a $\sim 500$ pc region before
disappearing due to proton-proton collisions. The observed diffuse GeV
gamma-rays resulting from the decay of neutral pions produced via collision
between these escaped protons and the gas in this region is expected to be
insensitive to time in the multi-injection model with the characteristic
injection rate of 10^{-5} yr^{-1}. Our model calculated GeV and 511 keV
gamma-ray intensities are consistent with the observed results of EGRET and
INTEGRAL, however, our calculated inflight annihilation rate cannot produce
sufficient intensity to explain the COMPTEL data.


title:
Orbital Order, Stripe Phases and Mott Transition in a Planar Model for
  Manganites

abstract:
  Understanding orbital ordered (OO) Mott insulating states lies at the heart
of a consistent resolution of the colossal magneto-resistance (CMR) observed in
manganites, where its melting induces a low-$T$ insulator-metal transition for
$0.25 \le x\le 0.45$. Motivated thereby, we study the OO states in a planar
model for bilayer manganites using DMFT and finite-size diagonalisation
methods. We derive the correct OO ground states observed in manganites for
$x=0,{1/2},{2/3},{3/4}$ in exact agreement with observations, including the
charge-orbital-magnetic ordered stripe phases for $x>{1/2}$. These OO states
are {\it exactly} shown to be associated with an ``alloy'' ordering of the
$d_{3x^{2}-r^{2}}/d_{3y^{2}-r^{2}}$ orbitals on each $Mn^{3+}$ site.


title: Geometric Invariant Theory via Cox Rings

abstract:
  We consider actions of reductive groups on a varieties with finitely
generated Cox ring, e.g., the classical case of a diagonal action on a product
of projective spaces. Given such an action, we construct via combinatorial data
in the Cox ring all maximal open subsets such that the quotient is
quasiprojective or embeddable into a toric variety. As applications, we obtain
an explicit description of the chamber structure of the linearized ample cone
and several Gelfand-MacPherson type correspondences relating quotients of
reductive groups to quotients of torus actions. Moreover, our approach provides
information on the geometry of many of the resulting quotient spaces.


title: A counterexample to generalizations of the Milnor-Bloch-Kato conjecture

abstract:
  We construct an example of a torus $T$ over a field $K$ for which the Galois
symbol $K(K; T,T)/n K(K; T,T) \to H^2(K, T[n]\otimes T[n])$ is not injective
for some $n$. Here $K(K; T,T)$ is the Milnor $K$-group attached to $T$
introduced by Somekawa. We show also that the motive $M(T\times T)$ gives a
counterexample to another generalization of the Milnor-Bloch-Kato conjecture
(proposed by Beilinson).


title: Phase Space Constraints on Neutrino Luminosities

abstract:
  While the importance of phase space constraints for gravitational clustering
of neutrinos (which are fermions) is well recognized, the explicit use of such
constraints to limit neutrino emission from ultra energetic sources has not
been stressed. Special and general relativistic phase space constraints are
shown to limit neutrino luminosities in compact sources in various situations.


title: A three-dimensional backward-wave network matched with free space

abstract:
  A backward-wave slab based on a capacitively and inductively loaded
three-dimensional transmission-line network is designed in such a way that
impedance-matching with free space is obtained. To enable field propagation
from free space to the network and vice versa, the use of a transition layer is
proposed. Matching of the designed network with free space and negative
refraction occurring at the slab interfaces are confirmed with full-wave
simulations.


title:
Nuclear deformation and the two neutrino double-\beta decay in
  ^{124,126}Xe,^{128,130}Te, ^{130,132}Ba and ^{150}Nd isotopes

abstract:
  The two neutrino double beta decay of $^{124,126}$Xe,$^{128,130}$Te, $
^{130,132}$Ba and $^{150}$Nd isotopes is studied in the Projected
Hartree-Fock-Bogoliubov (PHFB) model. Theoretical 2$\nu $ $\beta^{-}\beta ^{-}$
half-lives of $^{128,130}$Te, and $^{150}$Nd isotopes, and 2$\nu
\beta^{+}\beta^{+}$, 2$\nu $ $\beta^{+}EC$ and 2$\nu $ $ECEC$ for $
^{124,126}$Xe and $^{130,132}$Ba nuclei are presented. Calculated quadrupolar
transition probabilities B(E2: $0^+\to 2^+$), static quadrupole moments and $g$
factors in the parent and daughter nuclei reproduce the experimental
information, validating the reliability of the model wave functions. The
anticorrelation between nuclear deformation and the nuclear transition matrix
element $M_{2\nu} $ is confirmed.


title: On Wahl's proof of $\mu(6)=65$

abstract:
  D. Jaffe and D. Ruberman proved in 1997 that a sextic hypersurface in
$\mathbb{P}^3$ has at most 65 nodes (the bound is sharp by Barth's
construction).
  Almost at the same time, J. Wahl proposed a much shorter proof of the same
result, by proving that a linear code $V\subset \F^{66}$ with weights in
$\{24,32,40\}$ has dimension $\dim(V)\leq12$.
  He claimed that Jaffe-Ruberman's theorem follows as a corollary since the
code associated to a sextic with n nodes has dimension at least $n-53$ and an
incorrect result stated by Casnati and Catanese asserted that the possible
cardinalities of an even set of nodes on a sextic were only 24, 32 and 40.
  Recently Catanese and Tonoli showed that the possible cardinalities of an
even set of nodes on a sextic are exactly 24, 32, 40, 56. According to the
above cardinalities, the theorem of Jaffe and Ruberman reduces to the
following:
  Let $V\subset \F^{66}$ be a code with weights in $\{24,32,40,56\}$. Then
$\dim(V)\leq12$.
  In this short note we give an elementary proof of this theorem using and
integrating Wahl's ideas.


title: Existence of positive representations for complex weights

abstract:
  The necessity of computing integrals with complex weights over manifolds with
a large number of dimensions, e.g., in some field theoretical settings, poses a
problem for the use of Monte Carlo techniques. Here it is shown that very
general complex weight functions P(x) on R^d can be represented by real and
positive weights p(z) on C^d, in the sense that for any observable f, <f(x)>_P
= <f(z)>_p, f(z) being the analytical extension of f(x). The construction is
extended to arbitrary compact Lie groups.


title: Cold r-Process in Neutrino-Driven Winds

abstract:
  The r-process in a low temperature environment is explored, in which the
neutron emission by photodisintegration does not play a role (cold r-process).
A semi-analytic neutrino-driven wind model is utilized for this purpose. The
temperature in a supersonically expanding outflow can quickly drop to a few
10^8 K, where the (n, gamma)-(gamma, n) equilibrium is never achieved during
the heavy r-nuclei synthesis. In addition, the neutron capture competes with
the beta-decay owing to the low matter density. Despite such non-standard
physical conditions for the cold r-process, a solar-like r-process abundance
curve can be reproduced. The cold r-process predicts, however, the low lead
production compared to that expected in the traditional r-process conditions,
which can be a possible explanation for the low lead abundances found in a
couple of r-process-rich Galactic halo stars.


title: J/psi production in Indium-Indium collisions at 158 GeV/nucleon

abstract:
  The NA60 experiment studies muon pair production at the CERN SPS. In this
letter we report on a precision measurement of J/psi in In-In collisions. We
have studied the J/psi centrality distribution, and we have compared it with
the one expected if absorption in cold nuclear matter were the only active
suppression mechanism. For collisions involving more than ~80 participant
nucleons, we find that an extra suppression is present. This result is in
qualitative agreement with previous Pb-Pb measurements by the NA50 experiment,
but no theoretical explanation is presently able to coherently describe both
results.


title: A Special Nonlinear Connection in Second Order Geometry

abstract:
  We show that, for mechanical system with external forces, the equations of
deviations of solution curves of the corresponding Lagrange equations,determine
a nonlinear connection on the second order osculator (second order tangent)
bundle. In particular, Jacobi equations in Finsler and Riemann spaces determine
such a nonlinear connection.


title: Vacuum polarization and plasma oscillations

abstract:
  We evidence the existence of plasma oscillations of electrons-positron pairs
created by the vacuum polarization in an uniform electric field with E < Ec.
Our general treatment, encompassing also the traditional, well studied case of
E > Ec, shows the existence in both cases of a maximum Lorentz factor acquired
by electrons and positrons and allows determination of the a maximal length of
oscillation. We quantitatively estimate how plasma oscillations reduce the rate
of pair creation and increase the time scale of the pair production. These
results are particularly relevant in view of the experimental progress in
approaching the field strengths E < Ec.


title:
Transverse $\Lambda^0$ polarization in inclusive photoproduction: quark
  recombination model

abstract:
  Transverse polarization of $\Lambda^0$ hyperons in inclusive photoproduction
at x_F>0 is tackled within the framework of the quark recombination model,
which has been successfully applied to the polarization of different hyperons
in a variety of unpolarized hadron-hadron reactions. The results are compared
with recent experimental data of HERMES.


title: Multi-dimensional BSDE with Oblique Reflection and Optimal Switching

abstract:
  In this paper, we study a multi-dimensional backward stochastic differential
equation (BSDE) with oblique reflection, which is a BSDE reflected on the
boundary of a special unbounded convex domain along an oblique direction, and
which arises naturally in the study of optimal switching problem. The existence
of the adapted solution is obtained by the penalization method, the monotone
convergence, and the a priori estimations. The uniqueness is obtained by a
verification method (the first component of any adapted solution is shown to be
the vector value of a switching problem for BSDEs). As applications, we apply
the above results to solve the optimal switching problem for stochastic
differential equations of functional type, and we give also a probabilistic
interpretation of the viscosity solution to a system of variational
inequalities.


title: Gauge-independent Abelian mechanism of color confinement in gluodynamics

abstract:
  Abelian mechanism of non-Abelian color confinement is observed in a
gauge-independent way by high precision lattice Monte Carlo simulations in
gluodynamics. An Abelian gauge field is extracted with no gauge-fixing. A
static quark-antiquark potential derived from Abelian Polyakov loop correlators
gives us the same string tension as the non-Abelian one. The Hodge
decomposition of the Abelian Polyakov loop correlator to the regular photon and
the singular monopole parts also reveals that only the monopole part is
responsible for the string tension. The investigation of the flux-tube profile
then shows that Abelian electric fields defined in an arbitrary color direction
are squeezed by monopole supercurrents with the same color direction, and the
quantitative features of flux squeezing are consistent with those observed
previously after Abelian projections with gauge fixing. Gauge independence of
Abelian and monopole dominance strongly supports that the mechanism of
non-Abelian color confinement is due to the Abelian dual Meissner effect.


title:
Muon spin rotation measurements of the superfluid density in fresh and
  aged superconducting PuCoGa$_5$

abstract:
  We have measured the temperature dependence and magnitude of the superfluid
density $\rho_{\rm s}(T)$ via the magnetic field penetration depth $\lambda(T)$
in PuCoGa$_5$ (nominal critical temperature $T_{c0} = 18.5$ K) using the muon
spin rotation technique in order to investigate the symmetry of the order
parameter, and to study the effects of aging on the superconducting properties
of a radioactive material. The same single crystals were measured after 25 days
($T_c = 18.25$ K) and 400 days ($T_c = 15.0$ K) of aging at room temperature.
The temperature dependence of the superfluid density is well described in both
materials by a model using d-wave gap symmetry. The magnitude of the muon spin
relaxation rate $\sigma$ in the aged sample, $\sigma\propto
1/\lambda^2\propto\rho_s/m^*$, where $m^*$ is the effective mass, is reduced by
about 70% compared to fresh sample. This indicates that the scattering from
self-irradiation induced defects is not in the limit of the conventional
Abrikosov-Gor'kov pair-breaking theory, but rather in the limit of short
coherence length (about 2 nm in PuCoGa$_5$) superconductivity.


title: Combinatorial and geometric methods in topology

abstract:
  Starting from the (apparently) elementary problem of deciding how many
different topological spaces can be obtained by gluing together in pairs the
faces of an octahedron, we will describe the central role played by hyperbolic
geometry within three-dimensional topology. We will also point out the striking
difference with the two-dimensional case, and we will review some of the
results of the combinatorial and computational approach to three-manifolds
developed by different mathematicians over the last several years.


title: The role of HST in the study of near- and mid-infrared-selected galaxies

abstract:
  Because of their unique quality, Hubble Space Telescope (HST) data have
played an important complementary role in studies of infrared (IR) galaxies
conducted with major facilities, as VLT or Spitzer, and will be as well very
valuable for future telescopes as Herschel and ALMA. I review here some of the
most recent works led by European astronomers on IR galaxies, and discuss the
role that HST has had in the study of different IR galaxy populations. I
particularly focus the analysis on the GOODS fields, where the multiwavelength
data and unique HST coverage have enabled to jointly put constraints on the
evolution of star formation activity and stellar-mass growth with cosmic time.


title:
Role of the exchange and correlation potential into calculating the
  x-ray absorption spectra of half-metallic alloys: the case of Mn and Cu
  K-edge XANES in Cu$_2$MnM (M = Al, Sn, In) Heusler alloys

abstract:
  This work reports a theoretical study of the x-ray absorption near-edge
structure spectra at both the Cu and the Mn K-edge in several Cu$_2$MnM (M= Al,
Sn and In) Heusler alloys. Our results show that {\it ab-initio} single-channel
multiple-scattering calculations are able of reproducing the experimental
spectra. Moreover, an extensive discussion is presented concerning the role of
the final state potential needed to reproduce the experimental data of these
half-metallic alloys. In particular, the effects of the cluster-size and of the
exchange and correlation potential needed in reproducing all the experimental
XANES features are discussed.


title:
The VIMOS-VLT Deep Survey. The dependence of clustering on galaxy
  stellar mass at z~1

abstract:
  Aims: We use the VVDS-Deep first-epoch data to measure the dependence of
galaxy clustering on galaxy stellar mass, at z~0.85.
  Methods: We measure the projected correlation function wp(rp) for sub-samples
with 0.5<z<1.2 covering different mass ranges between 10^9 and 10^11 Msun. We
quantify in detail the observational selection biases using 40 mock catalogues
built from the Millennium run and semi-analytic models.
  Results: Our simulations indicate that serious incompleteness in mass is
present only for log(M/Msun)<9.5. In the mass range log(M/Msun)=[9.0-9.5], the
photometric selection function of the VVDS misses 2/3rd of the galaxies. The
sample is virtually 100% complete above 10^10 Msun. We present the first direct
evidence for a clear dependence of clustering on the galaxy stellar mass at
z~0.85. The clustering length increases from r0 ~ 2.76 h^-1 Mpc for galaxies
with mass M>10^9 Msun to r0 ~ 4.28 h^-1 Mpc for galaxies more massive than
10^10.5 Msun. At the same time, the slope increases from ~ 1.67 to ~ 2.28.
  A comparison of the observed wp(rp) to local measurements by the SDSS shows
that the evolution is faster for objects less massive than ~10^10.5 Msun. This
is interpreted as a higher dependence on redshift of the linear bias b_L for
the more massive objects. While for the most massive galaxies b_L decreases
from 1.5+/-0.2 at z~0.85 to 1.33+/-0.03 at z~0.15, the less massive population
maintains a virtually constant value b_L~1.3. This result is in agreement with
a scenario in which more massive galaxies formed at high redshift in the
highest peaks of the density field, while less massive objects form at later
epochs from the more general population of dark-matter halos.