title: Quantum Tunneling and Trace Anomaly

abstract:
  We compute the corrections, using the tunneling formalisim based on a quantum
WKB approach, to the Hawking temperature and Bekenstein-Hawking entropy for the
Schwarzschild black hole. The results are related to the trace anomaly and are
shown to be equivalent to findings inferred from Hawking's original calculation
based on path integrals using zeta function regularization. Finally, exploiting
the corrected temperature and periodicity arguments we also find the
modification to the original Schwarzschild metric which captures the effect of
quantum corrections.


title:
Optimal Power Allocation for Fading Channels in Cognitive Radio
  Networks: Ergodic Capacity and Outage Capacity

abstract:
  A cognitive radio network (CRN) is formed by either allowing the secondary
users (SUs) in a secondary communication network (SCN) to opportunistically
operate in the frequency bands originally allocated to a primary communication
network (PCN) or by allowing SCN to coexist with the primary users (PUs) in PCN
as long as the interference caused by SCN to each PU is properly regulated. In
this paper, we consider the latter case, known as spectrum sharing, and study
the optimal power allocation strategies to achieve the ergodic capacity and the
outage capacity of the SU fading channel under different types of power
constraints and fading channel models. In particular, besides the interference
power constraint at PU, the transmit power constraint of SU is also considered.
Since the transmit power and the interference power can be limited either by a
peak or an average constraint, various combinations of power constraints are
studied. It is shown that there is a capacity gain for SU under the average
over the peak transmit/interference power constraint. It is also shown that
fading for the channel between SU transmitter and PU receiver is usually a
beneficial factor for enhancing the SU channel capacities.


title:
Entanglement dynamics of two-qubit system in different types of noisy
  channels

abstract:
  In this paper, we study entanglement dynamics of a two-qubit extended
Werner-like state locally interacting with independent noisy channels, i.e.,
amplitude damping, phase damping and depolarizing channels. We show that the
purity of initial entangled state has direct impacts on the entanglement
robustness in each noisy channel. That is, if the initial entangled state is
prepared in mixed instead of pure form, the state may exhibit entanglement
sudden death (ESD) and/or be decreased for the critical probability at which
the entanglement disappear.


title:
Towards relating the kappa-symmetric and pure-spinor versions of the
  supermembrane

abstract:
  We study the relation between the kappa-symmetric formulation of the
supermembrane in eleven dimensions and the pure-spinor version. Recently,
Berkovits related the Green-Schwarz and pure-spinor superstrings. In this
paper, we attempt to extend this method to the supermembrane. We show that it
is possible to reinstate the reparameterisation constraints in the pure-spinor
formulation of the supermembrane by introducing a topological sector and
performing a similarity transformation. The resulting BRST charge is then of
conventional type and is argued to be (related to) the BRST charge of the
kappa-symmetric supermembrane in a formulation where all second class
constraints are 'gauge unfixed' to first class constraints. In our analysis we
also encounter a natural candidate for a (non-covariant) supermembrane analogue
of the superstring b ghost.


title: Dynamical suppression of non-adiabatic modes

abstract:
  Recent analyses of the WMAP 5-year data constrain possible non-adiabatic
contributions to the initial conditions of CMB anisotropies. Depending upon the
early dynamics of the plasma, the amplitude of the entropic modes can
experience a different suppression by the time of photon decoupling. Explicit
examples of the latter observation are presented both analytically and
numerically when the post-inflationary dynamics is dominated by a stiff
contribution.


title: Providing Virtual Execution Environments: A Twofold Illustration

abstract:
  Platform virtualization helps solving major grid computing challenges: share
resource with flexible, user-controlled and custom execution environments and
in the meanwhile, isolate failures and malicious code. Grid resource management
tools will evolve to embrace support for virtual resource.
  We present two open source projects that transparently supply virtual
execution environments. Tycoon has been developed at HP Labs to optimise
resource usage in creating an economy where users bid to access virtual
machines and compete for CPU cycles. SmartDomains provides a peer-to-peer layer
that automates virtual machines deployment using a description language and
deployment engine from HP Labs. These projects demonstrate both client-server
and peer-to-peer approaches to virtual resource management. The first case
makes extensive use of virtual machines features for dynamic resource
allocation. The second translates virtual machines capabilities into a
sophisticated language where resource management components can be plugged in
configurations and architectures defined at deployment time.
  We propose to share our experience at CERN openlab developing SmartDomains
and deploying Tycoon to give an illustrative introduction to emerging research
in virtual resource management.


title:
Studying Geometric Graph Properties of Road Networks Through an
  Algorithmic Lens

abstract:
  This paper studies real-world road networks from an algorithmic perspective,
focusing on empirical studies that yield useful properties of road networks
that can be exploited in the design of fast algorithms that deal with
geographic data. Unlike previous approaches, our study is not based on the
assumption that road networks are planar graphs. Indeed, based on the a number
of experiments we have performed on the road networks of the 50 United States
and District of Columbia, we provide strong empirical evidence that road
networks are quite non-planar. Our approach therefore instead is directed at
finding algorithmically-motivated properties of road networks as non-planar
geometric graphs, focusing on alternative properties of road networks that can
still lead to efficient algorithms for such problems as shortest paths and
Voronoi diagrams. In particular, we study road networks as multiscale-dispersed
graphs, which is a concept we formalize in terms of disk neighborhood systems.
This approach allows us to develop fast algorithms for road networks without
making any additional assumptions about the distribution of edge weights. In
fact, our algorithms can allow for non-metric weights.


title:
Planning Curricular Proposals on Sound and Music with Prospective
  Secondary-School Teachers

abstract:
  Sound is a preferred context to build foundations on wave phenomena, one of
the most important disciplinary referents in physics. It is also one of the
best-set frameworks to achieve transversality, overcoming scholastic level and
activating emotional aspects which are naturally connected with every day life,
as well as with music and perception. Looking at sound and music by a
transversal perspective - a border-line approach between science and art, is
the adopted statement for a teaching proposal using meta-cognition as a
strategy in scientific education. This work analyzes curricular proposals on
musical acoustics, planned by prospective secondary-school teachers in the
framework of a Formative Intervention Module answering the expectation of
making more effective teaching scientific subjects by improving creative
capabilities, as well as leading to build logical and scientific
categorizations able to consciously discipline artistic activity in music
students. With this aim, a particular emphasis is given to those concepts -
like sound parameters and structural elements of a musical piece, which are
best fitted to be addressed on a transversal perspective, involving
simultaneously physics, psychophysics and music.


title: Higgs Boson Production in Association with Multiple Hard Jets

abstract:
  We elucidate a new technique for estimating the production of multiple (at
least two) hard jets in Higgs production via gluon-gluon fusion. The approach
is based upon high energy factorisation, with the region of applicability
extended by constraints on the analytic behaviour of the scattering amplitudes
stemming from known all-order results. The method approximates both real and
virtual corrections, and allows for the resummation in an n-parton inclusive
event sample of the terms dominant in the high energy limit. The resulting
approximation is matched to the known tree level matrix elements for the
production of a Higgs boson in association with 2 and 3 jets, and implemented
in a Monte Carlo generator. Example results are presented and characteristic
radiation patterns discussed.


title: Asymptotics of randomly stopped sums in the presence of heavy tails

abstract:
  We study conditions under which $P(S_\tau>x)\sim P(M_\tau>x)\sim E\tau
P(\xi_1>x)$ as $x\to\infty$, where $S_\tau$ is a sum $\xi_1+...+\xi_\tau$ of
random size $\tau$ and $M_\tau$ is a maximum of partial sums
$M_\tau=\max_{n\le\tau}S_n$. Here $\xi_n$, $n=1$, 2, ..., are independent
identically distributed random variables whose common distribution is assumed
to be subexponential. We consider mostly the case where $\tau$ is independent
of the summands; also, in a particular situation, we deal with a stopping time.
  Also we consider the case where $E\xi>0$ and where the tail of $\tau$ is
comparable with or heavier than that of $\xi$, and obtain the asymptotics
$P(S_\tau>x) \sim E\tau P(\xi_1>x)+P(\tau>x/E\xi)$ as $x\to\infty$. This case
is of a primary interest in the branching processes.
  In addition, we obtain new uniform (in all $x$ and $n$) upper bounds for the
ratio $P(S_n>x)/P(\xi_1>x)$ which substantially improve Kesten's bound in the
subclass ${\mathcal S}^*$ of subexponential distributions.


title:
Monopoles in the presence of the Chern-Simons term via the
  Julia-Toulouse approach

abstract:
  We study $QED_3$ with magnetic-like defects using the Julia-Toulouse
condensation mechanism (JTM). By a careful treatment of the symmetries we
suggest a geometrical interpretation for distinct debatable issues in the
MCS-monopole system: (i) the induction of the non-conserved electric current
together with the Chern-Simons term (CS), (ii) the deconfinement transition
and, (iii) the computation of the fermionic determinant in the presence of
Dirac string singularities. The JTM leads to proper interpretation of the
non-conserved current as originating from Dirac brane symmetry breaking. The
mechanism behind this symmetry breaking is clarified. The physical origin of
the deconfinement transition becomes evident in the low energy effective theory
induced by the JTM. The proper procedure to compute the fermionic determinant
in the presence of Dirac branes will be presented. A byproduct of this approach
is the possible appearance of statistical transmutation and the clarification
for the different quantization rules for the topological mass.


title: Difficulties with Collapse Interpretations of Quantum Mechanics

abstract:
  Quantum mechanics gives many versions of reality but we perceive only one.
One potential explanation for this, the one considered here, is that the wave
function collapses down to just one version. The experimental situation is
briefly reviewed, with no evidence found for collapse. The theoretical position
is also reviewed and found wanting. Collapse-by-observation schemes are
logically untenable. A mathematical theory of collapse must be nonlinear, a
significant departure from current quantum theory. In addition, the primary
candidate theory, the GRW-Pearle model, requires instantaneous, non-local
transmission of information. It also requires transmission of information
across versions of reality, which is forbidden in current quantum mechanics.
And there is no apparent physical quantity, such as particle number, that can
provide the mechanism for collapse in all cases. Further, these aspects, which
are in disagreement with current theory, seem to be necessary for any
mathematical theory of collapse. The conclusion is that the outlook for
mathematical collapse schemes is not encouraging.


title: Survival probability in diffractive dijet photoproduction

abstract:
  We confront the latest H1 and ZEUS data on diffractive dijet photoproduction
with next-to-leading order QCD predictions in order to determine whether a
rapidity gap survival probability of less than one is supported by the data. We
find evidence for this hypothesis when assuming global factorization breaking
for both the direct and resolved photon contributions, in which case the
survival probability would have to be E_T^jet-dependent, and for the resolved
or in addition the related direct initial-state singular contribution only,
where it would be independent of E_T^jet.


title: Crossing the Phantom Divide Line in a DGP-Inspired $F(R,\phi)$-Gravity

abstract:
  We study possible crossing of the phantom divide line in a DGP-inspired
$F(R,\phi)$ braneworld scenario where scalar field and curvature quintessence
are treated in a unified framework. With some specific form of $F(R,\phi)$ and
by adopting a suitable ansatz, we show that there are appropriate regions of
the parameters space which account for late-time acceleration and admit
crossing of the phantom divide line.


title:
Quantum Hall to Insulator Transition in the Bilayer Quantum Hall
  Ferromagnet

abstract:
  We describe a new phase transition of the bilayer quantum Hall ferromagnet at
filling fraction $\nu = 1$. In the presence of static disorder (modeled by a
periodic potential), bosonic $S=1/2$ spinons can undergo a superfluid-insulator
transition while preserving the ferromagnetic order. The Mott insulating phase
has an emergent U(1) photon, and the transition is between Higgs and Coulomb
phases of this photon. Physical consequences for charge and counterflow
conductivity, and for interlayer tunneling conductance in the presence of
quenched disorder are discussed.


title: Scalar and gauge translation-invariant noncommutative models

abstract:
  We make here a short overview of the recent developments regarding
translation-invariant models on the noncommutative Moyal space. A scalar model
was first proposed and proved renormalizable. Its one-loop renormalization
group flow and parametric representation were calculated. Furthermore, a
mechanism to take its commutative limit was recently given. Finally, a
proposition for a renormalizable, translation-invariant gauge model was made.


title: Polygonal excitations of spinning and levitating droplets

abstract:
  The shape of a weightless spinning liquid droplet is governed by the balance
between the surface tension and centrifugal forces. The axisymmetric shape for
slow rotation becomes unstable to a non-axisymmetric distortion above a
critical angular velocity, beyond which the droplet progresses through a series
of 2-lobed shapes. Theory predicts the existence of a family of 3- and 4-lobed
equilibrium shapes at higher angular velocity. We investigate the formation of
a triangular-shaped magnetically levitated water droplet, driven to rotate by
the Lorentz force on an ionic current within the droplet. We also study
equatorial traveling waves which give the droplet 3, 4 and 5-fold symmetry.


title: Current Fluctuations in Rough Superconducting Tunnel Junctions

abstract:
  Intrinsic noise is known to be ubiquitous in Josephson junctions. We
investigate a voltage biased superconducting tunnel junction including a very
small number of pinholes - transport channels possessing a transmission
coefficient close to unity. Although few of these pinholes contribute very
little to the conductance, they can dominate current fluctuations in the
low-voltage regime. We show that even fully transparent transport channels
between superconductors contribute to shot noise due to the uncertainty in the
number of Andreev cycles. We discuss shot noise enhancement by Multiple Andreev
Reflection in such a junction and investigate whether pinholes might contribute
as a microscopic mechanism of two-level current fluctuators. We discuss the
connection of these results to the junction resonators observed in Josephson
phase qubits.


title:
Theory of the nonsteady diffusion growth of a gas bubble in a
  supersaturated solution of gas in liquid

abstract:
  Using a self-similar approach a general nonsteady theory is elaborated for
the case of the diffusion growth of a gas bubble in a supersaturated solution
of gas in liquid. Due to the fact that the solution and the bubble in it are
physically isolated, the self-similar approach accounts for the balance of the
number of gas molecules in the solution and in the bubble that expells
incompressible liquid solvent while growing. The rate of growth of the bubble
radius in its dependence from gas solubility and solution supersaturation is
obtained. There is a nonsteady effect of rapid increase of the rate of bubble
growth simultaneous with the growth of the product of gas solubility and
solution supersaturation. This product is supplied with a limitation from
above, which also stipulates isothermal conditions of bubble growth. The
smallness of gas solubility is not presupposed.


title: X-ray clusters of galaxies in conformal gravity

abstract:
  We run adiabatic N-body/hydrodynamical simulations of isolated
self-gravitating gas clouds to test whether conformal gravity, an alternative
theory to General Relativity, is able to explain the properties of X-ray galaxy
clusters without resorting to dark matter. We show that the gas clouds rapidly
reach equilibrium with a density profile which is well fit by a beta-model
whose normalization and slope are in approximate agreement with observations.
However, conformal gravity fails to yield the observed thermal properties of
the gas cloud: (i) the mean temperature is at least an order of magnitude
larger than observed; (ii) the temperature profiles increase with the square of
the distance from the cluster center, in clear disagreement with real X-ray
clusters. These results depend on a gravitational potential whose parameters
reproduce the velocity rotation curves of spiral galaxies. However, this
parametrization stands on an arbitrarily chosen conformal factor. It remains to
be seen whether a different conformal factor, specified by a spontaneous
breaking of the conformal symmetry, can reconcile this theory with
observations.


title: Collectivity-induced quenching of signatures for shell closures

abstract:
  Mass differences are an often used as signature and measure for shell
closure. Using the angular-momentum projected Generator Coordinate Method and
the Skyrme interaction SLy4, we analyze the modification of mass differences
due to static deformation and dynamic fluctuations around the mean-field ground
state.


title:
Entanglement dynamics and Bell Violations of two atoms in Tavis-Cummings
  model with phase decoherence

abstract:
  Considering the dipole-dipole coupling intensity between two atoms and the
field in the Fock state, the entanglement dynamics between two atoms that are
initially entangled in the system of two two-level atoms coupled to a single
mode cavity in the presence of phase decoherence has been investigated. The
two-atom entanglement appears with periodicity without considering phase
decoherence, however, the phase decoherence causes the decay of entanglement
between two atoms, with the increasing of the phase decoherence coefficient,
the entanglement will quickly become a constant value, which is affected by the
two-atom initial state, Meanwhile the two-atom quantum state will forever stay
in the maximal entangled state when the initial state is proper even in the
presence of phase decoherence. On the other hand, the Bell violation and the
entanglement does not satisfy the monotonous relation, a large Bell violation
implies the presence of a large amount of entanglement under certain
conditions, while a large Bell violation corresponding to a little amount of
entanglement in certain situations. However, the violation of Bell-CHSH
inequality can reach the maximal value if two atoms are in the maximal
entangled state, or vice versa.


title: T-matrix approach to heavy quark diffusion in the QGP

abstract:
  We assess transport properties of heavy quarks in the Quark-Gluon Plasma
(QGP) using static heavy-quark (HQ) potentials from lattice-QCD calculations in
a Brueckner many-body T-matrix approach to evaluate elastic
heavy-quark-light-quark scattering amplitudes. In the attractive meson and
diquark channels resonance states are formed for temperatures up to ~1.5 T_c,
increasing pertinent drag and diffusion coefficients for heavy-quark
rescattering in the QGP beyond the expectations from perturbative-QCD
calculations. We use these transport coefficients, complemented with
perturbative elastic HQ gluon scattering, in a relativistic Langevin simulation
to obtain HQ p_t distributions and elliptic flow (v_2) under conditions
relevant for the hot and dense medium created in ultrarelativistic heavy-ion
collisions. The heavy quarks are hadronized to open-charm and -bottom mesons
within a combined quark-coalescence fragmentation scheme. The resulting
single-electron spectra from their semileptonic decays are confronted with
recent data on "non-photonic electrons" in 100 AGeV Au-Au collisions at the
Relativistic Heavy-Ion Collider (RHIC).


title: Average Structures of a Single Knotted Ring Polymer

abstract:
  Two types of average structures of a single knotted ring polymer are studied
by Brownian dynamics simulations. For a ring polymer with N segments, its
structure is represented by a 3N -dimensional conformation vector consisting of
the Cartesian coordinates of the segment positions relative to the center of
mass of the ring polymer. The average structure is given by the average
conformation vector, which is self-consistently defined as the average of the
conformation vectors obtained from a simulation each of which is rotated to
minimize its distance from the average conformation vector. From each
conformation vector sampled in a simulation, 2N conformation vectors are
generated by changing the numbering of the segments. Among the 2N conformation
vectors, the one closest to the average conformation vector is used for one
type of the average structure. The other type of the averages structure uses
all the conformation vectors generated from those sampled in a simulation. In
thecase of the former average structure, the knotted part of the average
structure is delocalized for small N and becomes localized as N is increased.
In the case of the latter average structure, the average structure changes from
a double loop structure for small N to a single loop structure for large N,
which indicates the localization-delocalization transition of the knotted part.


title:
Critique du rapport signal \`a bruit en communications num\'eriques --
  Questioning the signal to noise ratio in digital communications

abstract:
  The signal to noise ratio, which plays such an important r\^ole in
information theory, is shown to become pointless for digital communications
where the demodulation is achieved via new fast estimation techniques.
Operational calculus, differential algebra, noncommutative algebra and
nonstandard analysis are the main mathematical tools.


title:
Nulling interferometry: performance comparison between space and
  ground-based sites for exozodiacal disc detection

abstract:
  Characterising the circumstellar dust around nearby main sequence stars is a
necessary step in understanding the planetary formation process and is crucial
for future life-finding space missions such as ESA's Darwin or NASA's
Terrestrial Planet Finder (TPF). Besides paving the technological way to
Darwin/TPF, the space-based infrared interferometers Pegase and FKSI
(Fourier-Kelvin Stellar Interferometer) will be valuable scientific precursors
in that respect. In this paper, we investigate the performance of Pegase and
FKSI for exozodiacal disc detection and compare the results with ground-based
nulling interferometers. Besides their main scientific goal (characterising hot
giant extrasolar planets), Pegase and FKSI are very efficient in assessing
within a few minutes the level of circumstellar dust in the habitable zone
around nearby main sequence stars. They are capable of detecting exozodiacal
discs respectively 5 and 1 time as dense as the solar zodiacal cloud and they
outperform any ground-based instrument. Unlike Pegase, FKSI can achieve this
sensitivity for most targets of the Darwin/TPF catalogue thanks to an
appropriate combination of baseline length and observing wavelength. The
sensitivity of Pegase could, however, be significantly boosted by considering a
shorter interferometric baseline length. These space-based interferometers
would be complementary to Antarctica-based instruments in terms of sky coverage
and would be ideal instruments for preparing future life-finding space
missions.


title: On nonadiabatic calculation of dipole moments

abstract:
  We show that a recent non Born--Oppenheimer calculation of dipole moments
exhibits obscure points and is not consistent with the well known
Hellmann--Feynman theorem.


title:
Nanostructure and related mechanical properties of an Al-Mg-Si alloy
  processed by severe plastic deformation

abstract:
  Microstructural features and mechanical properties of an Al-Mg-Si alloy
processed by high-pressure torsion have been investigated using transmission
electron microscopy, X-ray diffraction, three-dimensional atom probe, tensile
tests and microhardness measurements. It is shown that HPT processing of the
Al-Mg-Si alloy leads to a much stronger grain size refinement than of pure
aluminium (down to 100 nm). Moreover, massive segregation of alloying elements
along grain boundaries is observed. This nanostructure exhibits a yield stress
even two times higher than that after a standard T6 heat treatment of the
coarse grained alloy


title:
Precipitate stability and recrystallisation in the weld nuggets of
  friction stir welded Al-Mg-Si and Al-Mg-Sc alloys

abstract:
  Two different precipitate hardening aluminium alloys processed by friction
stir welding were investigated. The microstructure and the hardness of the as
delivered materials were compared to that of the weld nugget. Transmission
electron microscopy observations combined with three-dimensional atom probe
analyses clearly show that \beta;" precipitates dissolved in the nugget of the
Al-Mg-Si giving rise to some supersaturated solid solution. It is shown that
the dramatic softening of the weld could be partly recovered by post-welding
ageing treatments. In the Al-Mg-Sc alloy, Al3Sc precipitate size and density
are unchanged in the nugget comparing to the base metal. These precipitates
strongly reduce the boundary mobility of recrystallised grains, leading to a
grain size in the nugget much smaller than in the Al-Mg-Si alloy. Both coherent
and incoherent precipitates were detected. This feature may indicate that a
combination of continuous and discontinuous recrystallisation occurred in the
weld nugget.


abstract:
  Development organizations and International Non-Governmental Organizations
have been emphasizing the high potential of Free and Open Source Software for
the Less Developed Countries. Cost reduction, less vendor dependency and
increased potential for local capacity development have been their main
arguments. In spite of its advantages, Free and Open Source Software is not
widely adopted at the African continent. In this book the authors will explore
the grounds on with these expectations are based. Where do they come from and
is there evidence to support these expectations? Over the past years several
projects have been initiated and some good results have been achieved, but at
the same time many challenges were encountered. What lessons can be drawn from
these experiences and do these experiences contain enough evidence to support
the high expectations? Several projects and their achievements will be
considered. In the final part of the book the future of Free and Open Source
Software for Development will be explored. Special attention is given to the
African continent since here challenges are highest. What is the role of Free
and open Source Software for Development and how do we need to position and
explore the potential? What are the threats? The book aims at professionals
that are engaged in the design and implementation of ICT for Development
(ICT4D) projects and want to improve their understanding of the role Free and
Open Source Software can play.


title: An X-ray photometry system I: Chandra ACIS

abstract:
  We present a system of X-ray photometry for the Chandra satellite. X-ray
photometry can be a powerful tool to obtain flux estimates, hardness ratios,
and colors unbiased by assumptions about spectral shape and independent of
temporal and spatial changes in instrument characteristics. The system we have
developed relies on our knowledge of effective area and the energy-to-channel
conversion to construct filters similar to photometric filters in the optical
bandpass. We show that the filters are well behaved functions of energy and
that this X-ray photometric system is able to reconstruct fluxes to within
about 20%, without color corrections, for non-pathological spectra. Even in the
worst cases it is better than 50%. Our method also treats errors in a
consistent manner, both statistical as well as systematic.


title:
Radial quadrupole and scissors modes in trapped Fermi gases across the
  BCS phase transition

abstract:
  The excitation spectra of the radial quadrupole and scissors modes of
ultracold Fermi gases in elongated traps are studied across the BCS
superfluid-normal phase transition in the framework of a transport theory for
quasiparticles. In the limit of zero temperature, this theory reproduces the
results of superfluid hydrodynamics, while in the opposite limit, above the
critical temperature, it reduces to the collisionless Vlasov equation. In the
intermediate temperature range, the excitation spectra have two or three broad
peaks, respectively, which are roughly situated at hydrodynamic and
collisionless frequencies, and whose strength is shifted from the hydrodynamic
to the collisionless modes with increasing temperature. By fitting the time
dependent quadrupole deformation with a damped oscillation of a single
frequency, we can understand the "jump" of the frequency of the radial
quadrupole mode as a function of interaction strength which has recently been
reported by the Innsbruck group.


title: Light-matter excitations in the ultra-strong coupling regime

abstract:
  In a microcavity, light-matter coupling is quantified by the vacuum Rabi
frequency $\Omega_R$. When $\Omega_R$ is larger than radiative and
non-radiative loss rates, the system eigenstates (polaritons) are linear
superposition of photonic and electronic excitations, a condition actively
investigated in diverse physical implementations. Recently, a quantum
electrodynamic regime (ultra-strong coupling) was predicted when $\Omega_R$
becomes comparable to the transition frequency. Here we report unambiguous
signatures of this regime in a quantum-well intersubband microcavity. Measuring
the cavity-polariton dispersion in a room-temperature linear optical
experiment, we directly observe the anti-resonant light-matter coupling and the
photon-energy renormalization of the vacuum field.


title:
Integral formulation of 3-D Navier-Stokes and longer time existence of
  smooth solutions

abstract:
  We consider the 3-D Navier-Stokes initial value problem, $$ v_t - \nu \Delta
v = -\mathcal{P} [ v \cdot \nabla v ] + f , v(x, 0) = v_0 (x), x \in
\mathbb{T}^3 (*) $$ where $\mathcal{P}$ is the Hodge projection. We assume that
the Fourier transform norms $ \| {\hat f} \|_{l^1 (\mathbb{Z}^3)}$ and $\|
{\hat v}_0 \|_{l^{1} (\mathbb{Z}^3)}$ are finite. Using an inverse Laplace
transform approach, we prove that an integral equation equivalent to (*) has a
unique solution ${\hat U} (k, q)$, exponentially bounded for $q$ in a sector
centered on $\RR^+$, where $q$ is the inverse Laplace dual to $1/t^n$ for $n
\ge 1$. This implies in particular local existence of a classical solution to
(*) for $t \in (0, T)$, where $T$ depends on $\| {\hat v}_0 \|_{l^{1}}$ and $\|
{\hat f} \|_{l^1}$. Global existence of the solution to NS follows if $\| {\hat
U} (\cdot, q) \|_{l^1}$ has subexponential bounds as $q\to\infty$. If $f=0$,
then the converse is also true: if NS has global solution, then there exists $n
\ge 1 $ for which $\| {\hat U} (\cdot, q) \|$ necessarily decays. We show the
exponential growth rate bound of U, \alpha, can be better estimated based on
the values of ${\hat U}$ on a finite interval $[0,q_0]$. We also show how the
integral equation can be solved numerically with controlled errors. Preliminary
numerical calculations suggest that this approach gives an existence time that
substantially exceeds classical estimate.


title:
Imaging galactic diffuse gas: Bright, turbulent CO surrounding the line
  of sight to NRAO150

abstract:
  To understand the environment and extended structure of the host galactic gas
whose molecular absorption line chemistry, we previously observed along the
microscopic line of sight to the blazar/radiocontinuum source NRAO150 (aka
B0355+508), we used the IRAM 30m Telescope and Plateau de Bure Interferometer
to make two series of images of the host gas: i) 22.5 arcsec resolution
single-dish maps of 12CO J=1-0 and 2-1 emission over a 220 arcsec by 220 arcsec
field; ii) a hybrid (interferometer+singledish) aperture synthesis mosaic of
12CO J=1-0 emission at 5.8 arcsec resolution over a 90 arcsec-diameter region.
CO components that are observed in absorption at a moderate optical depth (0.5)
and are undetected in emission at 1 arcmin resolution toward NRAO 150 remain
undetected at 6 arcsec resolution. This implies that they are not a
previously-hidden large-scale molecular component revealed in absorption, but
they do highlight the robustness of the chemistry into regions where the
density and column density are too low to produce much rotational excitation,
even in CO. Bright CO lines around NRAO150 most probably reflect the variation
of a chemical process, i.e. the C+-CO conversion. However, the ultimate cause
of the variations of this chemical process in such a limited field of view
remains uncertain.


title: Stellar Evolution in the Early Universe

abstract:
  Massive stars played a key role in the early evolution of the Universe. They
formed with the first halos and started the re-ionisation. It is therefore very
important to understand their evolution. In this paper, we describe the strong
impact of rotation induced mixing and mass loss at very low $Z$. The strong
mixing leads to a significant production of primary nitrogen 14, carbon 13 and
neon 22. Mass loss during the red supergiant stage allows the production of
Wolf-Rayet stars, type Ib,c supernovae and possibly gamma-ray bursts (GRBs)
down to almost Z=0 for stars more massive than 60 solar masses. Galactic
chemical evolution models calculated with models of rotating stars better
reproduce the early evolution of N/O, C/O and C12/C13. We calculated the weak
s-process production induced by the primary neon 22 and obtain overproduction
factors (relative to the initial composition, Z=1.e-6) between 100-1000 in the
mass range 60-90.


title: On The Origins Of Eccentric Close-in Planets

abstract:
  Strong tidal interaction with the central star can circularize the orbits of
close-in planets. With the standard tidal quality factor Q of our solar system,
estimated circularization times for close-in extrasolar planets are typically
shorter than the ages of the host stars. While most extrasolar planets with
orbital radii a < 0.1 AU indeed have circular orbits, some close-in planets
with substantial orbital eccentricities have recently been discovered. This new
class of eccentric close-in planets implies that either their tidal Q factor is
considerably higher, or circularization is prevented by an external
perturbation. Here we constrain the tidal Q factor for transiting extrasolar
planets by comparing their circularization times with accurately determined
stellar ages. Using estimated secular perturbation timescales, we also provide
constraints on the properties of hypothetical second planets exterior to the
known ones.


title:
New Positron Spectral Features from Supersymmetric Dark Matter - a Way
  to Explain the PAMELA Data?

abstract:
  The space-borne antimatter experiment PAMELA has recently reported a
surprising rise in the positron to electron ratio at high energies. It has also
recently been found that electromagnetic radiative corrections in some cases
may boost the gamma-ray yield from supersymmetric dark matter annihilations in
the galactic halo by up to three or four orders of magnitude, providing
distinct spectral signatures for indirect dark matter searches to look for.
Here, we investigate whether the same type of corrections can also lead to
sizeable enhancements in the positron yield. We find that this is indeed the
case, albeit for a smaller region of parameter space than for gamma rays;
selecting models with a small mass difference between the neutralino and
sleptons, like in the stau coannihilation region in mSUGRA, the effect becomes
more pronounced. The resulting, rather hard positron spectrum with a relatively
sharp cutoff may potentially fit the rising positron ratio measured by the
PAMELA satellite. To do so, however, very large "boost factors" have to be
invoked that are not expected in current models of halo structure. If the
predicted cutoff would also be confirmed by later PAMELA data or upcoming
experiments, one could either assume non-thermal production in the early
universe or non-standard halo formation to explain such a spectral feature as
an effect of dark matter annihilation. At the end of the paper, we briefly
comment on the impact of radiative corrections on other annihilation channels,
in particular antiprotons and neutrinos.


title:
Highly accurate recommendation algorithm based on high-order
  similarities

abstract:
  In this Letter, we introduce a modified collaborative filtering (MCF)
algorithm, which has remarkably higher accuracy than the standard collaborative
filtering. In the MCF, instead of the standard Pearson coefficient, the
user-user similarities are obtained by a diffusion process. Furthermore, by
considering the second order similarities, we design an effective algorithm
that depresses the influence of mainstream preferences. The corresponding
algorithmic accuracy, measured by the ranking score, is further improved by
24.9% in the optimal case. In addition, two significant criteria of algorithmic
performance, diversity and popularity, are also taken into account. Numerical
results show that the algorithm based on second order similarity can outperform
the MCF simultaneously in all three criteria.


title: Thermal Flipping of Interstellar Grains

abstract:
  In interstellar dust grains, internal processes dissipate rotational kinetic
energy. The dissipation is accompanied by thermal fluctuations, which transfer
energy from the vibrational modes to rotation. Together, these processes are
known as internal relaxation. For the past several years, internal relaxation
has been thought to give rise to thermal flipping, with profound consequences
for grain alignment theory. I show that thermal flipping is not possible in the
limit that the inertia tensor does not vary with time.


title:
Non-uniform sampling, image recovery from sparse data and the discrete
  sampling theorem

abstract:
  In many applications sampled data are collected in irregular fashion or are
partly lost or unavailable. In these cases it is required to convert
irregularly sampled signals to regularly sampled ones or to restore missing
data. In this paper, we address this problem in a framework of a discrete
sampling theorem for band-limited discrete signals that have a limited number
of non-zero transform coefficients in a certain transform domain. Conditions
for the image unique recovery, from sparse samples, are formulated and then
analyzed for various transforms. Applications are demonstrated on examples of
image super-resolution and image reconstruction from sparse projections.


title: Gravitational time advancement and its possible detection

abstract:
  The gravitational time advancement is a natural but a consequence of curve
space-time geometry. In the present work the expressions of gravitational time
advancement have been obtained for geodesic motions. The situation when the
distance of signal travel is small in comparison to the distance of closest
approach has also been considered. The possibility of experimental detection of
time advancement effect has been explored.


title: A hyperbolic Out(F_n)-complex

abstract:
  For any finite collection $f_i$ of fully irreducible automorphisms of the
free group $F_n$ we construct a connected $\delta$-hyperbolic
$Out(F_n)$-complex in which each $f_i$ has positive translation length.


title:
K1(1270)-K1(1400) Mixing Angle and New-Physics Effects in B to K1 l+ l-
  Decays

abstract:
  We study semileptonic B meson decays B to K_1(1270) l^+ l^- and K_1(1400) l^+
l^- (l=e, mu, tau), where the strange P-wave mesons, K_1(1270) and K_1(1400),
are the mixtures of the K_{1A} and K_{1B}, which are the 1^3P_1 and 1^1P_1
states, respectively. We show that the ratio R_l = Br(B to K_1(1400) l^+
l^-)/Br(B to K_1(1270) l^+ l^-), insensitive to new-physics parameters, is
suitable for determining the K_1(1270)-K_1(1400) mixing angle, theta_{K_1}. The
forward-backward asymmetry shows a weak theta_{K_1}-dependence for B to
K_1(1270) mu^+ mu^-, but relatively strong for B to K_1(1400) mu^+ mu^-. We
investigate model-independent new-physics corrections to operators relevant to
the b to s l^+ l^- electroweak-penguin and weak-box diagrams. Furthermore, for
the B to K_1(1270) mu^+ mu^- decay the position of the forward-backward
asymmetry zero, which is almost independent of the value of theta_{K_1}, can be
dramatically changed under variation of new-physics parameters.


title: Survival of contact processes on the hierarchical group

abstract:
  We consider contact processes on the hierarchical group, where sites infect
other sites at a rate depending on their hierarchical distance, and sites
become healthy with a constant recovery rate. If the infection rates decay too
fast as a function of the hierarchical distance, then we show that the critical
recovery rate is zero. On the other hand, we derive sufficient conditions on
the speed of decay of the infection rates for the process to exhibit a
nontrivial phase transition between extinction and survival. For our sufficient
conditions, we use a coupling argument that compares contact processes on the
hierarchical group with freedom two with contact processes on a renormalized
lattice. An interesting novelty in this renormalization argument is the use of
a result due to Rogers and Pitman on Markov functionals.


title:
The abstract Titchmarsh-Weyl M-function for adjoint operator pairs and
  its relation to the spectrum

abstract:
  In the setting of adjoint pairs of operators we consider the question: to
what extent does the Weyl M-function see the same singularities as the
resolvent of a certain restriction $A_B$ of the maximal operator? We obtain
results showing that it is possible to describe explicitly certain spaces $\Sc$
and $\tilde{\Sc}$ such that the resolvent bordered by projections onto these
subspaces is analytic everywhere that the M-function is analytic. We present
three examples -- one involving a Hain-L\"{u}st type operator, one involving a
perturbed Friedrichs operator and one involving a simple ordinary differential
operators on a half line -- which together indicate that the abstract results
are probably best possible.


title:
Self-consistent study of Anderson localization in the Anderson-Hubbard
  model in two and three dimensions

abstract:
  We consider the change in electron localization due to the presence of
electron-electron repulsion in the \HA model. Taking into account local
Mott-Hubbard physics and static screening of the disorder potential, the system
is mapped onto an effective single-particle Anderson model, which is studied
within the self-consistent theory of electron localization. We find rich
nonmonotonic behavior of the localization length $\xi$ in two-dimensional
systems, including an interaction-induced exponential enhancement of $\xi$ for
small and intermediate disorders although $\xi$ remains finite. In three
dimensions we identify for half filling a Mott-Hubbard-assisted Anderson
localized phase existing between the metallic and the Mott-Hubbard-gapped
phases. For small $U$ there is re-entrant behavior from the Anderson localized
phase to the metallic phase.


title: Topological Confinement and Superconductivity

abstract:
  We derive a Kondo Lattice model with a correlated conduction band from a
two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence
of a robust pairing mechanism in a model that only contains repulsive
interactions. The mechanism is due to topological confinement and results from
the interplay between antiferromagnetism and delocalization. By using
Density-Matrix-Renormalization-Group (DMRG), we demonstrate that this mechanism
leads to dominant superconducting correlations in a 1D-system.


title:
Vacuum polarization by fermionic fields in higher dimensional cosmic
  string space-time

abstract:
  In this paper we investigate vacuum polarization effects associated with
charged massive quantum fermionic fields in a six-dimensional cosmic string
space-times considering the presence of a magnetic flux running along its core.
We have shown that for specific values of the parameters which codify the
presence of the cosmic string, and the fractional part of the ratio of the
magnetic flux by the quantum one, a closed expression for the respective Green
function is obtained. Adopting this result, we explicitly calculate the
renormalized vacuum expectation value of the energy-momentum tensors,
$<T^A_B>_{Ren}$, and analyse this result in some limitting cases.


title:
Asymptotic behavior of eigenvalues of Schr\"odinger type operators with
  degenerate kinetic energy

abstract:
  We study the eigenvalues of Schr\"odinger type operators $T +
  \lambda V$ and their asymptotic behavior in the small coupling limit
  $\lambda \to 0$, in the case where the symbol of the kinetic energy,
  $T(p)$, strongly degenerates on a non-trivial manifold of codimension one.


title:
Coherent control of magnetization precession in ferromagnetic
  semiconductor (Ga,Mn)As

abstract:
  We report single-color, time resolved magneto-optical measurements in
ferromagnetic semiconductor (Ga,Mn)As. We demonstrate coherent optical control
of the magnetization precession by applying two successive ultrashort laser
pulses. The magnetic field and temperature dependent experiments reveal the
collective Mn-moment nature of the oscillatory part of the time-dependent Kerr
rotation, as well as contributions to the magneto-optical signal that are not
connected with the magnetization dynamics.


title: Leptogenesis in the E$_6$SSM: Flavour Dependent Lepton Asymmetries

abstract:
  We discuss flavour dependent lepton asymmetries in the Exceptional
Supersymmetric Standard Model (E$_6$SSM). In the E$_6$SSM, the right-handed
neutrinos do not participate in gauge interactions, and they decay into leptons
and leptoquarks. Their Majorana nature allows violation of lepton number. New
particles and interactions can result in substantial lepton asymmetries, even
for scales as low as $10^6 {\rm GeV}$.


title: The Lie Algebra of Local Killing Fields

abstract:
  We present an algebraic procedure that finds the Lie algebra of the local
Killing fields of a smooth metric. In particular, we determine the number of
independent local Killing fields about a given point on the manifold. Spaces of
constant curvature and locally symmetric spaces are also discussed.
Furthermore, we obtain a complete classification of the Lie algebra of local
Killing fields for surfaces in terms of conditions upon the Gauss curvature.


title: Geometric Approach to the Weil-Petersson Symplectic Form

abstract:
  In a family of compact, canonically polarized, complex manifolds the first
variation of the lengths of closed geodesics is computed. As an application, we
show the coincidence of the Fenchel-Nielsen and Weil-Petersson symplectic forms
on the Teichmueller spaces of compact Riemann surfaces in a purely geometric
way. The method can also be applied to situations like moduli spaces of
weighted punctured Riemann surfaces, where the methods of Kleinian groups are
not available.


title: Valley density-wave and multiband superconductivity in Fe-pnictides

abstract:
  The key feature of the Fe-based superconductors is their quasi 2D multiband
Fermi surface. By relating the problem to a negative U Hubbard model and its
superconducting ground state, we show that the defining instability of such a
Fermi surface is the valley density-wave (VDW), a combined spin/charge
density-wave at the wavevector connecting the electron and hole valleys. As the
valley parameters change by doping or pressure, the fictitious superconductor
experiences "Zeeman splitting", eventually going into a non-uniform
"Fulde-Ferrell-Larkin-Ovchinikov" (FFLO) state, an itinerant and often
incommensurate VDW of the real world, characterized by the metallic
conductivity from the ungapped remnants of the Fermi surface. When "Zeeman
splitting" exceeds the "Chandrasekhar-Clogston" limit, the "FFLO" state
disappears, and the VDW is destabilized. Near this point, the VDW fluctuations
and interband pair repulsion are essential ingredients of high-Tc
superconductivity in Fe-pnictides.


title: Some questions about $\mathcal G$-bundles on curves

abstract:
  We define the notion of a parahoric group scheme $\mathcal G$ over a smooth
projective curve, and formulate four conjectures on the structure of the stack
of $\mathcal G$-bundles, which generalize to this case well-known results on
$G$-bundles with $G$ a constant reductive group. The conjectures concern the
set of connected components, the uniformization by affine flag varieties of
twisted loop groups, the Picard groups, and the space of global sections of a
dominant line bundle. Since a first version of this paper was circulated,
Heinloth [arXiv:0711.4450] has proved a good part of these conjectures.


title: High-(Energy)-Lights -- The Very High Energy Gamma-Ray Sky

abstract:
  The high-lights of ground-based very-high-energy (VHE, $E>100$ GeV) gamma-ray
astronomy are reviewed. The summary covers both Galactic and extra-galactic
sources. A total of at least 70 sources are currently known. Implications for
our understanding of the non-thermal Universe are discussed. The next
generation of ground based gamma-ray instruments aims to cover the entire
accessible energy range from as low as $\approx 10$ GeV up to $10^5$ GeV and to
improve the sensitivity by an order of magnitude in comparison with current
instruments.


title: Noncommutative Q-Lumps

abstract:
  Q-lumps associated with the noncommutative CP^N model in 2+1 dimensions are
constructed. These are solitonic configurations which are time dependent and
rotate with constant angular frequency. Energy of the Q-lumps is E=2 \pi k +
\alpha |Q|, and we find that in a regime in which the noncommutativity
parameter \theta is related to the moduli determining the size of the lumps, it
can be viewed to depend on \theta via the Noether charge Q. We present a
collective coordinate-type analysis signalling that CP^1 Q-lumps remain stable
under small radiative perturbations.


title: A game-theoretic version of Oakes' example for randomized forecasting

abstract:
  Using the game-theoretic framework for probability, Vovk and Shafer. have
shown that it is always possible, using randomization, to make sequential
probability forecasts that pass any countable set of well-behaved statistical
tests. This result generalizes work by other authors, who consider only tests
of calbration.
  We complement this result with a lower bound. We show that Vovk and Shafer's
result is valid only when the forecasts are computed with unrestrictedly
increasing degree of accuracy.
  When some level of discreteness is fixed, we present a game-theoretic
generalization of Oakes' example for randomized forecasting that is a test
failing any given method of deferministic forecasting; originally, this example
was presented for deterministic calibration.


title: Forward Correction and Fountain codes in Delay Tolerant Networks

abstract:
  Delay tolerant Ad-hoc Networks make use of mobility of relay nodes to
compensate for lack of permanent connectivity and thus enable communication
between nodes that are out of range of each other. To decrease delivery delay,
the information that needs to be delivered is replicated in the network. Our
objective in this paper is to study replication mechanisms that include coding
in order to improve the probability of successful delivery within a given time
limit. We propose an analytical approach that allows to quantify tradeoffs
between resources and performance measures (energy and delay). We study the
effect of coding on the performance of the network while optimizing parameters
that govern routing. Our results, based on fluid approximations, are compared
to simulations which validate the model


title:
Charge dynamics in the normal state of the iron oxypnictide
  superconductor LaFePO

abstract:
  We present the first infrared and optical study in the normal state of
ab-plane oriented single crystals of the iron-oxypnictide superconductor
LaFePO. We find that this material is a low carrier density metal with a
moderate level of correlations and exhibits signatures of electron-boson
coupling. The data is consistent with the presence of coherent quasiparticles
in LaFePO.


title:
A supersymmetric version of the quark model, and supersymmetry breaking
  for the Leptons, Baryons and Hadronic Mesons: Cybersusy V

abstract:
  Cybersusy is a new mechanism for supersymmetry breaking in the standard
supersymmetric model (SSM). Here we note that the superpotential for the SSM
has a set of thirteen invariances, five of which are well known, and eight of
which are new. The eight new invariances generate a sort of supersymmetric
quark and lepton model, together with supersymmetry breaking that makes the
squarks and sleptons very heavy. This breaking regenerates the standard model
out of the supersymmetric standard model, except that the gauge particles are
not yet included in this reduction. In this paper, it is shown that, with some
continued effort, cybersusy will make some predictions for hadron masses that
may actually be wrong, so that it is a supersymmetry breaking theory that can
be proved wrong! This is the fifth paper in what was intended to be a series of
four papers on cybersusy.


title:
The emergence of coherent magnetic excitations in the pseudogap phase of
  La2-xSrxCuO4

abstract:
  We use inelastic neutron scattering to measure the magnetic excitations in
the underdoped superconductor La2-xSrxCuO4 (x=0.085, Tc=22 K) over energy and
temperatures ranges 5 < E < 200 meV and 5 < T < 300 K respectively. At high
temperature (T = 300 K), we observe strongly damped excitations with a
characteristic energy scale of approximately 50 meV. As the temperature is
lowered to T = 30 K, and we move into the pseudogap state, the magnetic
excitations become highly structured in energy and momentum below about 60 meV.
This change appears to be associated with the development of the pseudogap in
the electronic excitations.


title:
Necessary and sufficient conditions for the existence of the q-optimal
  measure

abstract:
  This paper presents the general form and essential properties of the
q-optimal measure following the approach of Delbaen and Schachermayer (1996)
and proves its existence under mild conditions. Most importantly, it states a
necessary and sufficient condition for a candidate measure to be the q-optimal
measure in the case even of signed measures. Finally, an updated
characterization of the q-optimal measure for continuous asset price processes
is presented in the light of the counterexample appearing in Cerny and Kallsen
(2006) concerning Hobson's (2004) approach.


title: QCD Sum Rules and 1/$N_c$ expansion

abstract:
  The 1/$N_c$ arguments are developed to classify the hadronic states in the
correlators. Arguments applied to the $\sigma$ meson correlator enable to
separate the instanton, glueball, and, in particular, the $\pi\pi$ scattering
states by $1/N_c$ from both 2q and 4q correlators. The bare resonance pole with
no mixing effects are analyzed with the QCD sum rules (QSR). The results
suggest the existence of nontrivial correlation for the mass reduction of 4q
system.


title:
Hilbert-Chow morphism for non commutative Hilbert schemes and moduli
  spaces of linear representations

abstract:
  Let $k$ be a commutative ring and let $R$ be a commutative $k-$algebra. The
aim of this paper is to define and discuss some connection morphisms between
schemes associated to the representation theory of a (non necessarily
commutative) $R-$algebra $A. $ We focus on the scheme $\ran//\GL_n$ of the
$n-$dimensional representations of $A, $ on the Hilbert scheme $\Hilb_A^n$
parameterizing the left ideals of codimension $n$ of $A$ and on the affine
scheme Spec $\Gamma_R^n(A)^{ab} $ of the abelianization of the divided powers
of order $n$ over $A. $
  We give a generalization of the Grothendieck-Deligne norm map from
$\Hilb_A^n$ to Spec $\Gamma_R^n(A)^{ab} $ which specializes to the Hilbert Chow
morphism on the geometric points when $A$ is commutative and $k$ is an
algebraically closed field. Describing the Hilbert scheme as the base of a
principal bundle we shall factor this map through the moduli space
$\ran//\GL_n$ giving a nice description of this Hilbert-Chow morphism, and
consequently proving that it is projective.


title: Thermal Casimir effect in ideal metal rectangular boxes

abstract:
  The thermal Casimir effect in ideal metal rectangular boxes is considered
using the method of zeta functional regularization. The renormalization
procedure is suggested which provides the finite expression for the Casimir
free energy in any restricted quantization volume. This expression satisfies
the classical limit at high temperature and leads to zero thermal Casimir force
for systems with infinite characteristic dimensions. In the case of two
parallel ideal metal planes the results, as derived previously using thermal
quantum field theory in Matsubara formulation and other methods, are reproduced
starting from the obtained expression. It is shown that for rectangular boxes
the temperature-dependent contribution to the electromagnetic Casimir force can
be both positive and negative depending on side lengths. The numerical
computations of the scalar and electromagnetic Casimir free energy and force
are performed for cubes


title:
Occupation times of subcritical branching immigration system with Markov
  motions

abstract:
  We consider a branching system consisting of particles moving according to a
Markov family in $\Rd$ and undergoing subcritical branching with a constant
rate $V>0$. New particles immigrate to the system according to homogeneous
space-time Poisson random field. The process of the fluctuations of the
rescaled occupation time is studied with very mild assumptions on the Markov
family. In this general setting a functional central limit theorem is proved.
The subcriticality of the branching law is crucial for the limit behaviour and
in a sense overwhelms the properties of the particles' motion. It is for this
reason that the limit is the same for all dimensions and can be obtained for a
wide class of Markov processes. Another consequence is the form of the limit -
$\SP$-valued Wiener process with a simple temporal structure and a complicated
spatial one. This behaviour contrasts sharply with the case of critical
branching systems.


title:
Approaching Blokh-Zyablov Error Exponent with Linear-Time
  Encodable/Decodable Codes

abstract:
  Guruswami and Indyk showed in [1] that Forney's error exponent can be
achieved with linear coding complexity over binary symmetric channels. This
paper extends this conclusion to general discrete-time memoryless channels and
shows that Forney's and Blokh-Zyablov error exponents can be arbitrarily
approached by one-level and multi-level concatenated codes with linear
encoding/decoding complexity. The key result is a revision to Forney's general
minimum distance decoding algorithm, which enables a low complexity integration
of Guruswami-Indyk's outer codes into the concatenated coding schemes.


title:
Differentiable potentials and metallic states in disordered
  one-dimensional systems

abstract:
  We provide evidence that as a general rule Anderson localization effects
become weaker as the degree of differentiability of the disordered potential
increases. In one dimension a band of metallic states exists provided that the
disordered potential is sufficiently correlated and has some minimum degree of
differentiability. Several examples are studied in detail. In agreement with
the one parameter scaling theory the motion in the metallic region is ballistic
if the spectral density is smooth. Finally, we study the most promising
settings to observe these results in the context of cold atoms.


title: Parameters of Pseudo-Random Quantum Circuits

abstract:
  Pseudorandom circuits generate quantum states and unitary operators which are
approximately distributed according to the unitarily invariant Haar measure. We
explore how several design parameters affect the efficiency of pseudo-random
circuits, with the goal of identifying relevant trade-offs and optimizing
convergence. The parameters we explore include the choice of single- and
two-qubit gates, the topology of the underlying physical qubit architecture,
the probabilistic application of two-qubit gates, as well as circuit size,
initialization, and the effect of control constraints. Building on the
equivalence between pseudo-random circuits and approximate $t$-designs, a
Markov matrix approach is employed to analyze asymptotic convergence properties
of pseudo-random second-order moments to a 2-design. Quantitative results on
the convergence rate as a function of the circuit size are presented for qubit
topologies with a sufficient degree of symmetry. Our results may be
theoretically and practically useful to optimize the efficiency of random state
and operator generation.


title: Spontaneous free-boundary structure in crumpled membranes

abstract:
  We investigate the strong curvature that appears at the boundaries of a thin
crumpled elastic membrane. We account for these high-curvature regions in terms
of the stretching-ridge singularity believed to dominate the structure of
strongly deformed elastic membranes. Using a membrane fastened to itself to
form a bag shape with a single stretching ridge, we show that the creation of
points of high boundary curvature lowers the interior ridge's energy. In the
limit of small thickness, the induced curvature becomes arbitrarily strong on
the scale of the object size and results in sharp edges connecting interior
vertices to the boundary. REVISED: We analyze these edges as conical sectors
with no stretching. As the membrane size diverges, the edge energy grows as the
square root of the central ridge energy. For comparison, we discuss the effect
of truncating a stretching ridge at its ends. The effect of truncation becomes
appreciable when the truncation length is comparable to the width of the
untruncated ridge.


title: Hypergraph Ramsey numbers

abstract:
  The Ramsey number r_k(s,n) is the minimum N such that every red-blue coloring
of the k-tuples of an N-element set contains either a red set of size s or a
blue set of size n, where a set is called red (blue) if all k-tuples from this
set are red (blue). In this paper we obtain new estimates for several basic
hypergraph Ramsey problems. We give a new upper bound for r_k(s,n) for k \geq 3
and s fixed. In particular, we show that r_3(s,n) \leq 2^{n^{s-2}\log n}, which
improves by a factor of n^{s-2}/ polylog n the exponent of the previous upper
bound of Erdos and Rado from 1952. We also obtain a new lower bound for these
numbers, showing that there are constants c_1,c_2>0 such that r_3(s,n) \geq
2^{c_1 sn \log (n/s)} for all 4 \leq s \leq c_2n. When s is a constant, it
gives the first superexponential lower bound for r_3(s,n), answering an open
question posed by Erdos and Hajnal in 1972. Next, we consider the 3-color
Ramsey number r_3(n,n,n), which is the minimum N such that every 3-coloring of
the triples of an N-element set contains a monochromatic set of size n.
Improving another old result of Erdos and Hajnal, we show that r_3(n,n,n) \geq
2^{n^{c \log n}}. Finally, we make some progress on related hypergraph
Ramsey-type problems.


title:
Flavor symmetry for strong phases and determination of $\beta_s,
  \Delta\Gamma$ in $B_s \to J/\psi \phi$

abstract:
  Studies of angular and time distributions and CP-violating observables in
$B_s\to J/\psi \phi$ decays yield a space of parameters which can be
considerably reduced if relative strong phases among different amplitudes are
specified. We show that the relations between $B_s \to J/\psi \phi$ and $B^0
\to J/\psi K^{*0}$ amplitudes given by flavor symmetry [actually U(3) rather
than SU(3)] are likely to be quite reliable, and hence the use of strong phases
from $B^0 \to J/\psi K^{*0}$ in the analysis of $B_s \to J/\psi\phi$ is
justified. We point out the potential advantage of using helicity angles over
transversity angles, and comment on a way to measure a sizable CP-violating
phase independent of strong phases.


title:
The isocohomological property, higher Dehn functions, and relatively
  hyperbolic groups

abstract:
  The property that the polynomial cohomology with coefficients of a finitely
generated discrete group is canonically isomorphic to the group cohomology is
called the (weak) isocohomological property for the group. In the case when a
group is of type $HF^\infty$, i.e. that has a classifying space with the
homotopy type of a cellular complex with finitely many cells in each dimension,
we show that the isocohomological property is equivalent to the universal cover
of the classifying space satisfying polynomially bounded higher Dehn functions.
If a group is hyperbolic relative to a collection of subgroups, each of which
is polynomially combable (respectively $HF^\infty$ and isocohomological), then
we show that the group itself has these respective properties too. Combining
with the results of Connes-Moscovici and Dru{\c{t}}u-Sapir we conclude that a
group satisfies the Novikov conjecture if it is relatively hyperbolic to
subgroups that are of property RD, of type $HF^\infty$ and isocohomological.


title: The commutant of L(H) in its ultrapower may or may not be trivial

abstract:
  Kirchberg asked in 2004 whether the commutant of L(H)$ in its (norm)
ultrapower is trivial. Assuming the Continnuum Hypothesis, we prove that the
answer depends on the choice of the ultrafilter.


title: Strong and Electromagnetic Decays of X(1835) as a Baryonium State

abstract:
  With the assumption that the recently observed X(1835) is a baryonium state
we have studied the strong decays of $X(1835) \to \eta^{(\prime)} \pi^+ \pi^-,
\eta^{(\prime)} \pi^0 \pi^0$ and the electromagnetic decay of $X(1835) \to
2\gamma$ in the framework of effective Lagrangian formalism. In the present
investigation we have included the contributions from the iso-singlet light
scalar resonances but we have not included the isospin violating effect. Our
result for the strong decay of $X(1835) \to \eta^{\prime} \pi^+ \pi^-$ is
smaller than the observed data. The decay width for the radiative decay of
$X(1835) \to 2\gamma$ is consistent with the assumption that it decays through
the glueball. In addition, the width for the strong decay of $X(1835) \to \eta
\pi^+ \pi^-$ is larger than that of the strong decay of $X(1835) \to
\eta^{\prime} \pi^+ \pi^-$ due to the large phase space and coupling constant
$g_{N\bar{N}\eta}$. From our investigation, it is not possible to interpret
X(1835) as a baryonium.


title:
Could deformed special relativity naturally arise from the semiclassical
  limit of quantum gravity?

abstract:
  A argument is described for how deformed or doubly special relativity may
arise in the semiclassical limit of a quantum theory of gravity. We consider a
generic quantum theory of gravity coupled to matter, from which we use only the
assumption that a Hamiltonian constraint is imposed. We study circumstances in
which Lambda, G and hbar all may be separately neglected, but there may arise
terms in the ratio of particle energies to the Planck mass which are small but
measurable. Such cases include probes of an energy dependent speed of light
such as are possible in experiments such as MAGIC and GLAST. We show that in
such cases the leading order effect of quantum gravity will, if certain scaling
relations are satisfied, be to deform the metric in the effective Hamiltonian
of the matter quantum field theory by terms linear in energies. As the
Hamiltonian constraint has been imposed there can be no preferred time
coordinate or frame of reference, hence this is a modification rather than a
breaking of special relativity.


title:
Using Spatial Distributions to Constrain Progenitors of Supernovae and
  Gamma Ray Bursts

abstract:
  We carry out a comprehensive theoretical examination of the relationship
between the spatial distribution of optical transients and the properties of
their progenitor stars. By constructing analytic models of star-forming
galaxies and the evolution of stellar populations within them, we are able to
place constraints on candidate progenitors for core-collapse supernovae (SNe),
long-duration gamma ray bursts, and supernovae Ia. In particular we first
construct models of spiral galaxies that reproduce observations of
core-collapse SNe, and we use these models to constrain the minimum mass for
SNe Ic progenitors to approximately 25 solar masses. Secondly, we lay out the
parameters of a dwarf irregular galaxy model, which we use to show that the
progenitors of long-duration gamma-ray bursts are likely to have masses above
approximately 43 solar masses. Finally, we introduce a new method for
constraining the time scale associated with SNe Ia and apply it to our spiral
galaxy models to show how observations can better be analyzed to discriminate
between the leading progenitor models for these objects.


title: No large-angle correlations on the non-Galactic microwave sky

abstract:
  We investigate the angular two-point correlation function of temperature in
the WMAP maps. Updating and extending earlier results, we confirm the lack of
correlations outside the Galaxy on angular scales greater than about 60 degrees
at a level that would occur in 0.025 per cent of realizations of the
concordance model. This represents a dramatic increase in significance from the
original observations by the COBE-DMR and a marked increase in significance
from the first-year WMAP maps. Given the rest of the reported angular power
spectrum C_\ell, the lack of large-angle correlations that one infers outside
the plane of the Galaxy requires covariance among the C_\ell up to \ell=5.
Alternately, it requires both the unusually small (5 per cent of realizations)
full-sky large-angle correlations, and an unusual coincidence of alignment of
the Galaxy with the pattern of cosmological fluctuations (less than 2 per cent
of those 5 per cent). We argue that unless there is some undiscovered
systematic error in their collection or reduction, the data point towards a
violation of statistical isotropy. The near-vanishing of the large-angle
correlations in the cut-sky maps, together with their disagreement with results
inferred from full-sky maps, remain open problems, and are very difficult to
understand within the concordance model.


title: Toric Calabi-Yau four-folds dual to Chern-Simons-matter theories

abstract:
  We propose a new method to find gravity duals to a large class of
three-dimensional Chern-Simons-matter theories, using techniques from dimer
models. The gravity dual is given by M-theory on AdS_4\times Y_7, where Y_7 is
an arbitrary seven-dimensional toric Sasaki-Einstein manifold. The cone of Y_7
is a toric Calabi-Yau 4-fold, which coincides with a branch of the vacuum
moduli space of Chern-Simons-matter theories.


title: Effect of Helium Sedimentation on X-ray Measurements of Galaxy Clusters

abstract:
  The uniformity of the helium-to-hydrogen abundance ratio in X-ray emitting
intracluster medium (ICM) is one of the commonly adopted assumptions in X-ray
analyses of galaxy clusters and cosmological constraints derived from these
measurements. In this work, we investigate the effect of He sedimentation on
X-ray measurements of galaxy clusters in order to assess this assumption and
associated systematic uncertainties. By solving a set of flow equations for a
H-He plasma, we show that the helium-to-hydrogen mass ratio is significantly
enhanced in the inner regions of clusters. The effect of He sedimentation, if
not accounted for, introduces systematic biases in observable properties of
clusters derived using X-ray observations. We show that these biases also
introduce an apparent evolution in the observed gas mass fractions of X-ray
luminous, dynamically relaxed clusters and hence biases in observational
constraints on the dark energy equation of state parameter, w, derived from the
cluster distance-redshift relation. The Hubble parameter derived from the
combination of X-ray and Sunyaev-Zel'dovich effect (SZE) measurements is
affected by the He sedimentation process as well. Future measurements aiming to
constrain w or H_0 to better than 10% may need to take into account the effect
of He sedimentation. We propose that the evolution of gas mass fraction in the
inner regions of clusters should provide unique observational diagnostics of
the He sedimentation process.


title: Properties of the scale factor measure

abstract:
  We show that in expanding regions, the scale factor measure can be
reformulated as a local measure: Observations are weighted by integrating their
physical density along a geodesic that starts in the longest-lived metastable
vacuum. This explains why some of its properties are similar to those of the
causal diamond measure. In particular, both measures are free of Boltzmann
brains, subject to nearly the same conditions on vacuum stability. However, the
scale factor measure assigns a much smaller probability to the observed value
of the cosmological constant. The probability decreases further, like the
inverse sixth power of the primordial density contrast, if the latter is
allowed to vary.


title:
Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system.
  I. The non-dip spectrum in the low/hard state

abstract:
  We present analyses of a 50 ks observation of the supergiant X-ray binary
system Cygnus X-1/HDE 226868 taken with the Chandra High Energy Transmission
Grating Spectrometer (HETGS). Cyg X-1 was in its spectrally hard state and the
observation was performed during superior conjunction of the black hole,
allowing for the spectroscopic analysis of the accreted stellar wind along the
line of sight. A significant part of the observation covers X-ray dips as
commonly observed for Cyg X-1 at this orbital phase, however, here we only
analyze the high count rate non-dip spectrum. The full 0.5-10 keV continuum can
be described by a single model consisting of a disk, a narrow and a
relativistically broadened Fe Kalpha line, and a power law component, which is
consistent with simultaneous RXTE broad band data. We detect absorption edges
from overabundant neutral O, Ne and Fe, and absorption line series from highly
ionized ions and infer column densities and Doppler shifts. With emission lines
of He-like Mg XI, we detect two plasma components with velocities and densities
consistent with the base of the spherical wind and a focused wind. A simple
simulation of the photoionization zone suggests that large parts of the
spherical wind outside of the focused stream are completely ionized, which is
consistent with the low velocities (<200 km/s) observed in the absorption
lines, as the position of absorbers in a spherical wind at low projected
velocity is well constrained. Our observations provide input for models that
couple the wind activity of HDE 226868 to the properties of the accretion flow
onto the black hole.


title: A common mass scale for satellite galaxies of the Milky Way

abstract:
  The Milky Way has at least twenty-three known satellite galaxies that shine
with luminosities ranging from about a thousand to a billion times that of the
Sun. Half of these galaxies were discovered in the past few years in the Sloan
Digital Sky Survey, and they are among the least luminous galaxies in the known
Universe. A determination of the mass of these galaxies provides a test of
galaxy formation at the smallest scales and probes the nature of the dark
matter that dominates the mass density of the Universe. Here we use new
measurements of the velocities of the stars in these galaxies to show that they
are consistent with them having a common mass of about 10^7 M_\odot within
their central 300 parsecs. This result demonstrates that the faintest of the
Milky Way satellites are the most dark matter-dominated galaxies known, and
could be a hint of a new scale in galaxy formation or a characteristic scale
for the clustering of dark matter.


title: Area laws for the entanglement entropy - a review

abstract:
  Physical interactions in quantum many-body systems are typically local:
Individual constituents interact mainly with their few nearest neighbors. This
locality of interactions is inherited by a decay of correlation functions, but
also reflected by scaling laws of a quite profound quantity: The entanglement
entropy of ground states. This entropy of the reduced state of a subregion
often merely grows like the boundary area of the subregion, and not like its
volume, in sharp contrast with an expected extensive behavior. Such "area laws"
for the entanglement entropy and related quantities have received considerable
attention in recent years. They emerge in several seemingly unrelated fields,
in the context of black hole physics, quantum information science, and quantum
many-body physics where they have important implications on the numerical
simulation of lattice models. In this Colloquium we review the current status
of area laws in these fields. Center stage is taken by rigorous results on
lattice models in one and higher spatial dimensions. The differences and
similarities between bosonic and fermionic models are stressed, area laws are
related to the velocity of information propagation, and disordered systems,
non-equilibrium situations, classical correlation concepts, and topological
entanglement entropies are discussed. A significant proportion of the article
is devoted to the quantitative connection between the entanglement content of
states and the possibility of their efficient numerical simulation. We discuss
matrix-product states, higher-dimensional analogues, and states from
entanglement renormalization and conclude by highlighting the implications of
area laws on quantifying the effective degrees of freedom that need to be
considered in simulations.

categories: quant-ph cond-mat.other hep-th math-ph math.MP


title:
Formation of a Quasar Host Galaxy through a Wet Merger 1.4 Billion Years
  after the Big Bang

abstract:
  We present high-resolution Very Large Array imaging of the molecular gas in
the host galaxy of the high redshift quasar BRI 1335-0417 (z=4.41). Our CO(2-1)
observations have a linear resolution of 0.15" (1.0 kpc) and resolve the
molecular gas emission both spatially and in velocity. The molecular gas in BRI
1335-0417 is extended on scales of 5 kpc, and shows a complex structure. At
least three distinct components encompassing about two thirds of the total
molecular mass of 9.2 x 10^10 M_sun are identified in velocity space, which are
embedded in a structure that harbors about one third of the total molecular
mass in the system. The brightest CO(2-1) line emission region has a peak
brightness temperature of 61+/-9 K within 1 kpc diameter, which is comparable
to the kinetic gas temperature as predicted from the CO line excitation. This
is also comparable to the gas temperatures found in the central regions of
nearby ultra-luminous infrared galaxies, which are however much more compact
than 1 kpc. The spatial and velocity structure of the molecular reservoir in
BRI 1335-0417 is inconsistent with a simple gravitationally bound disk, but
resembles a merging system. Our observations are consistent with a major,
gas-rich (`wet') merger that both feeds an accreting supermassive black hole
(causing the bright quasar activity), and fuels a massive starburst that builds
up the stellar bulge in this galaxy. Our study of this z>4 quasar host galaxy
may thus be the most direct observational evidence that `wet' mergers at high
redshift are related to AGN activity.


title:
Observational evidence of CMEs interacting in the inner heliosphere as
  inferred from MHD simulations

abstract:
  The interaction of multiple Coronal Mass Ejections (CMEs) has been observed
by LASCO coronagraphs and by near-Earth spacecraft, and it is thought to be an
important cause of geo-effective storms, large Solar Energetic Particles events
and intense Type II radio bursts. New and future missions such as STEREO, the
LWS Sentinels, and the Solar Orbiter will provide additional observations of
the interaction of multiple CMEs between the Sun and the Earth. We present the
results of simulations of two and more CMEs interacting in the inner
heliosphere performed with the Space Weather Modeling Framework (SWMF). Based
on those simulations, we discuss the observational evidence of the interaction
of multiple CMEs, both in situ and from coronagraphs. The clearest evidence of
the interaction of the CMEs are the large temperature in the sheath, due to the
shocks merging, and the brightness increase in coronagraphic images, associated
with the interaction of the leading edges. The importance of having multiple
satellites at different distances and angular positions from the Sun is also
discussed.


title: Relativistic Lee Model on Riemannian Manifolds

abstract:
  We study the relativistic Lee model on static Riemannian manifolds. The model
is constructed nonperturbatively through its resolvent, which is based on the
so-called principal operator and the heat kernel techniques. It is shown that
making the principal operator well-defined dictates how to renormalize the
parameters of the model. The renormalization of the parameters are the same in
the light front coordinates as in the instant form. Moreover, the
renormalization of the model on Riemannian manifolds agrees with the flat case.
The asymptotic behavior of the renormalized principal operator in the large
number of bosons limit implies that the ground state energy is positive. In 2+1
dimensions, the model requires only a mass renormalization. We obtain rigorous
bounds on the ground state energy for the n-particle sector of 2+1 dimensional
model.


title: Toward precise constraints on growth of massive black holes

abstract:
  Growth of massive black holes (MBHs) in galactic centers comes mainly from
gas accretion during their QSO/AGN phases. In this paper we apply an extended
Soltan argument, connecting the local MBH mass function with the time-integral
of the QSO luminosity function, to the demography of MBHs and QSOs from recent
optical and X-ray surveys, and obtain robust constraints on the luminosity
evolution (or mass growth history) of individual QSOs (or MBHs). We find that
the luminosity evolution probably involves two phases: an initial exponentially
increasing phase set by the Eddington limit and a following phase in which the
luminosity declines with time as a power law (with a slope of -1.2--1.3) set by
a self-similar long-term evolution of disk accretion. Neither an evolution
involving only the increasing phase with a single Eddington ratio nor an
exponentially declining pattern in the second phase is likely. The period of a
QSO radiating at a luminosity higher than 10% of its peak value is about
(2-3)x10^8 yr, during which the MBH obtains ~80% of its mass. The
mass-to-energy conversion efficiency is $0.16\pm0.04 ^{+0.05}_{-0}$, with the
latter error accounting for the maximum uncertainty due to Compton-thick AGNs.
The expected Eddington ratios in QSOs from the constrained luminosity evolution
cluster around a single value close to 0.5-1 for high-luminosity QSOs and
extend to a wide range of lower values for low-luminosity ones. The Eddington
ratios for high luminosity QSOs appear to conflict with those estimated from
observations (~0.25) by using some virial mass estimators for MBHs in QSOs
unless the estimators systematically over-estimate MBH masses by a factor of
2-4. We also infer the fraction of optically obscured QSOs ~60-80%. Further
applications of the luminosity evolution of individual QSOs are also discussed.


title: Boltzmann brains and the scale-factor cutoff measure of the multiverse

abstract:
  To make predictions for an eternally inflating "multiverse", one must adopt a
procedure for regulating its divergent spacetime volume. Recently, a new test
of such spacetime measures has emerged: normal observers - who evolve in pocket
universes cooling from hot big bang conditions - must not be vastly outnumbered
by "Boltzmann brains" - freak observers that pop in and out of existence as a
result of rare quantum fluctuations. If the Boltzmann brains prevail, then a
randomly chosen observer would be overwhelmingly likely to be surrounded by an
empty world, where all but vacuum energy has redshifted away, rather than the
rich structure that we observe. Using the scale-factor cutoff measure, we
calculate the ratio of Boltzmann brains to normal observers. We find the ratio
to be finite, and give an expression for it in terms of Boltzmann brain
nucleation rates and vacuum decay rates. We discuss the conditions that these
rates must obey for the ratio to be acceptable, and we discuss estimates of the
rates under a variety of assumptions.


title: Probing local relaxation of cold atoms in optical superlattices

abstract:
  In the study of relaxation processes in coherent non-equilibrium dynamics of
quenched quantum systems, ultracold atoms in optical superlattices with
periodicity two provide a very fruitful test ground. In this work, we consider
the dynamics of a particular, experimentally accessible initial state prepared
in a superlattice structure evolving under a Bose-Hubbard Hamiltonian in the
entire range of interaction strengths, further investigating the issues raised
in Ref. [Phys. Rev. Lett. 101, 063001 (2008)]. We investigate the relaxation
dynamics analytically in the non interacting and hard core bosonic limits,
deriving explicit expressions for the dynamics of certain correlation
functions, and numerically for finite interaction strengths using the
time-dependent density-matrix renormalization (t-DMRG) approach. We can
identify signatures of local relaxation that can be accessed experimentally
with present technology. While the global system preserves the information
about the initial condition, locally the system relaxes to the state having
maximum entropy respecting the constraints of the initial condition. For finite
interaction strengths and finite times, the relaxation dynamics contains
signatures of the relaxation dynamics of both the non-interacting and hard core
bosonic limits.


title:
Creating Artificial Ice States Using Vortices in Nanostructured
  Superconductors

abstract:
  We demonstrate that it is possible to realize vortex ice states that are
analogous to square and kagome ice. With numerical simulations, we show that
the system can be brought into a state that obeys either global or local ice
rules by applying an external current according to an annealing protocol. We
explore the breakdown of the ice rules due to disorder in the nanostructure
array and show that in square ice, topological defects appear along grain
boundaries, while in kagome ice, individual defects appear. We argue that the
vortex system offers significant advantages over other artificial ice systems.


title: Radiation from relativistic jets

abstract:
  Nonthermal radiation observed from astrophysical systems containing
relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic
nuclei (AGNs), and Galactic microquasar systems usually have power-law emission
spectra. Recent PIC simulations of relativistic electron-ion
(electron-positron) jets injected into a stationary medium show that particle
acceleration occurs within the downstream jet. In the presence of relativistic
jets, instabilities such as the Buneman instability, other two-streaming
instability, and the Weibel (filamentation) instability create collisionless
shocks, which are responsible for particle (electron, positron, and ion)
acceleration. The simulation results show that the Weibel instability is
responsible for generating and amplifying highly nonuniform, small-scale
magnetic fields. These magnetic fields contribute to the electron's transverse
deflection behind the jet head. The ``jitter'' radiation from deflected
electrons in small-scale magnetic fields has different properties than
synchrotron radiation which is calculated in a uniform magnetic field. This
jitter radiation, a case of diffusive synchrotron radiation, may be important
to understand the complex time evolution and/or spectral structure in gamma-ray
bursts, relativistic jets, and supernova remnants.


title: KBSM of the product of a disk with two holes and S^{1}

abstract:
  We introduce diagrams and Reidemeister moves for links in FxS^{1}, where F is
an orientable surface. Using these diagrams we compute (in a new way) the
Kauffman Bracket Skein Modules (KBSM) for D^{2}xS^{1} and AxS^{1}, where D^{2}
is a disk and A is an annulus. Moreover, we also find the KBSM for the
F_{0,3}xS^{1}, where F_{0,3} denotes a disk with two holes, and thus show that
the module is free.


title: Angular correlations in three-jet events in ep collisions at HERA

abstract:
  Three-jet production in deep inelastic ep scattering and photoproduction was
investigated with the ZEUS detector at HERA using an integrated luminosity of
127 pb-1. Measurements of differential cross sections are presented as
functions of angular correlations between the three jets in the final state and
the proton-beam direction. These correlations provide a stringent test of
perturbative QCD and show sensitivity to the contributions from different
colour configurations. Fixed-order perturbative QCD calculations assuming the
values of the colour factors C_F, C_A and T_F as derived from a variety of
gauge groups were compared to the measurements to study the underlying gauge
group symmetry. The measured angular correlations in the deep inelastic ep
scattering and photoproduction regimes are consistent with the admixture of
colour configurations as predicted by SU(3) and disfavour other symmetry
groups, such as SU(N) in the limit of large N.


title: Heavy Flavour Physics at CDF

abstract:
  The CDF detector at Fermilab has accumulated more that 3/fb of data which
enables unprecedented studies of heavy flavor hadron properties. We present
recent CDF measurements of mass and lifetime of the Bc meson as well as
lifetime, mixing and CP violation properties of Bs mesons.


title: Poincare recurrences and transient chaos in systems with leaks

abstract:
  In order to simulate observational and experimental situations, we consider a
leak in the phase space of a chaotic dynamical system. We obtain an expression
for the escape rate of the survival probability applying the theory of
transient chaos. This expression improves previous estimates based on the
properties of the closed system and explains dependencies on the position and
size of the leak and on the initial ensemble. With a subtle choice of the
initial ensemble, we obtain an equivalence to the classical problem of Poincare
recurrences in closed systems, which is treated in the same framework. Finally,
we show how our results apply to weakly chaotic systems and justify a split of
the invariant saddle in hyperbolic and nonhyperbolic components, related,
respectively, to the intermediate exponential and asymptotic power-law decays
of the survival probability.


title: Electromagnetic turbulence driven by the mixed mode instability

abstract:
  In continuation of previous work, numerical results are presented, concerning
relativistically counter-streaming plasmas. Here, the relativistic mixed mode
instability evolves through, and beyond, the linear saturation -- well into the
nonlinear regime. Besides confirming earlier findings, that wave power
initially peaks on the mixed mode branch, it is observed that, during late time
evolution wave power is transferred to other wave numbers. It is argued that
the isotropization of power in wavenumber space may be a consequence of weak
turbulence. Further, some modifications to the ideal weak turbulence limit is
observed. Development of almost isotropic predominantly electrostatic --
partially electromagnetic -- turbulent spectra holds relevance when considering
the spectral emission signatures of the plasma, namely bremsstrahlung,
respectively magneto-bremsstrahlung (synchrotron radiation and jitter
radiation) from relativistic shocks in astrophysical jets and shocks from
gamma-ray bursts and active galactic nuclei.


title: The Chiral Anomaly in SCET

abstract:
  Anomalies are an infrared effect, but are often realized in effective
theories in a non-trivial way. We study the chiral anomaly in Soft Collinear
Effective Theory (SCET), where the anomaly equation has terms contributing at
different orders in the power expansion. The chiral anomaly equations in SCET
are computed up to NNLO in the power counting with external collinear and/or
ultrasoft gluons. We do this by expanding the QCD anomaly equation, using the
tree level (LO in \alpha_s) relations between QCD and SCET fields. The validity
of this correspondence between the anomaly equations is confirmed by direct
computation of the one-loop diagrams in SCET.


title:
Nonlinear Sigma Model Analysis of the AFM Phase Transition of the Kondo
  Lattice

abstract:
  We have studied the antiferromagnetic quantum phase transition of a 2D
Kondo-Heisenberg square lattice using the non-linear sigma model. A
renormalization group analysis of the competing Kondo -- RKKY interaction was
carried out to 1-loop order in the $\epsilon$ expansion, and a new quantum
critical point is found, dominated by Kondo fluctuations. In addition, the
spin-wave velocity scales logarithmically near the new QCP, i.e breakdown of
hydrodynamic behavior. The results allow us to propose a new phase diagram near
the AFM fixed point of this 2D Kondo lattice model.


title:
Magnetic phase evolution in the spinel compounds
  Zn$_{1-x}$Co$_x$Cr$_2$O$_4$

abstract:
  We present the magnetic properties of complete solid solutions of
ZnCr$_2$O$_4$ and CoCr$_2$O$_4$: two well-studied oxide spinels with very
different magnetic ground states. ZnCr$_2$O$_4$, with non-magnetic $d^{10}$
cations occupying the A site and magnetic $d^3$ cations on the B site, is a
highly frustrated antiferromagnet. CoCr$_2$O$_4$, with magnetic $d^7$ cations
(three unpaired electrons) on the A site as well, exhibits both N\'eel
ferrimagnetism as well as commensurate and incommensurate non-collinear
magnetic order. More recently, CoCr$_2$O$_4$ has been studied extensively for
its polar behavior which arises from conical magnetic ordering. Gradually
introducing magnetism on the A site of ZnCr$_2$O$_4$ results in a transition
from frustrated antiferromagnetism to glassy magnetism at low concentrations of
Co, and eventually to ferrimagnetic and conical ground states at higher
concentrations. Real-space Monte-Carlo simulations of the magnetic
susceptibility suggest that the first magnetic ordering transition and features
of the susceptibility across $x$ are captured by near-neighbor self- and
cross-couplings between the magnetic A and B atoms. We present as a part of
this study, a method for displaying the temperature dependence of magnetic
susceptibility in a manner which helps distinguish between compounds possessing
purely antiferromagnetic interactions from compounds where other kinds of
ordering are present.


title: Equilibrium policies when preferences are time inconsistent

abstract:
  This paper characterizes differentiable and subgame Markov perfect equilibria
in a continuous time intertemporal decision problem with non-constant
discounting. Capturing the idea of non commitment by letting the commitment
period being infinitesimally small, we characterize the equilibrium strategies
by a value function, which must satisfy a certain equation. The equilibrium
equation is reminiscent of the classical Hamilton-Jacobi-Bellman equation of
optimal control, but with a non-local term leading to differences in
qualitative behavior. As an application, we formulate an overlapping
generations Ramsey model where the government maximizes a utilitarian welfare
function defined as the discounted sum of successive generations' lifetime
utilities. When the social discount rate is different from the private discount
rate, the optimal command allocation is time inconsistent and we retain subgame
perfection as a principle of intergenerational equity. Existence of multiple
subgame perfect equilibria is established. The multiplicity is due to the
successive governments' inability to coordinate their beliefs and we single out
one of them as (locally) renegotiation-proof. Decentralization can be achieved
with both age and time dependent lump sum transfers and, long term distorting
capital interest income taxes/subsidy.


title: Light-cone expansion of heavy-to-light form factors

abstract:
  We present the results of our recent systematic study of the light-cone
expansion of heavy-to-light transition form factors in a model with scalar
constituents [1]. We show that the higher-twist contributions (represented in
this model by off-light-cone effects) all have the same behaviour in the 1/m_Q
expansion. The suppression parameter of the higher-twist contributions compared
to the lower-twist contributions is, in general, the inverse Borel parameter
\beta. The only exception here is the case of the leading and the subleading
twists: they are of the same order in 1/\beta because of an extra suppression
of the leading-twist contribution to the form factor.