title:
Quantum pathology of static internal imperfections in flawed quantum
  computers

abstract:
  Even in the absence of external influences the operability of a quantum
computer (QC) is not guaranteed because of the effects of residual one- and
two-body imperfections. Here we investigate how these internal flaws affect the
performance of a quantum controlled-NOT (CNOT) gate in an isolated flawed QC.
First we find that the performance of the CNOT gate is considerably better when
the two-body imperfections are strong. Secondly, we find that the largest
source of error is due to a coherent shift rather than decoherence or
dissipation. Our results suggest that the problem of internal imperfections
should be given much more attention in designing scalable QC architectures.


title: Probing internal bath dynamics by a Rabi oscillator-based detector

abstract:
  By exact numerical and master equation approaches, we show that a central
spin-1/2 can be configured to probe internal bath dynamics. System-bath
interactions cause Rabi oscillations in the detector and periodic behavior of
fidelity. This period is highly sensitive to the strength of the bath
self-interactions, and can be used to calculate the intra-bath coupling.


title: Features of ion acceleration by circularly polarized laser pulses

abstract:
  The characteristics of a MeV ion source driven by superintense, ultrashort
laser pulses with circular polarization are studied by means of
particle-in-cell simulations. Predicted features include high efficiency, large
ion density, low divergence and the possibility of femtosecond duration. A
comparison with the case of linearly polarized pulses is made.


title: Statistical Evidence for Three classes of Gamma-ray Bursts

abstract:
  Two different multivariate clustering techniques, the K-means partitioning
method and the Dirichlet process of mixture modeling, have been applied to the
BATSE Gamma-ray burst (GRB) catalog, to obtain the optimum number of coherent
groups. In the standard paradigm, GRB are classified in only two groups, the
long and short bursts. However, for both the clustering techniques, the optimal
number of classes was found to be three, a result which is consistent with
previous statistical analysis. In this classification, the long bursts are
further divided into two groups which are primarily differentiated by their
total fluence and duration and hence are named low and high fluence GRB.
Analysis of GRB with known red-shifts and spectral parameters suggests that low
fluence GRB have nearly constant isotropic energy output of 10^{52} ergs while
for the high fluence ones, the energy output ranges from 10^{52} to 10^{54}
ergs. It is speculated that the three kinds of GRBs reflect three different
origins: mergers of neutron star systems, mergers between white dwarfs and
neutron stars, and collapse of massive stars.


title: (0,2) Gauged Linear Sigma Model on Supermanifold

abstract:
  We construct (0,2), D=2 gauged linear sigma model on a supermanifold in both
the Abelian gauge group and the non-Abelian gauge group. The $\hat{U}$ operator
provides consistency conditions for satisfying the SUSY invariance. Contrary to
the Abelian gauge group, it is not essential to introduce the new operator in
order to check the exact SUSY invariance of the Lagrangian density. However, in
order to introduce the (0,2) chiral superfields, we need the $\hat{U}$
operator, because we can not define the (0,2) chirality conditions of the (0,2)
chiral superfields without introducing the new operator by using $\hat{U}$ and
the enlarged operator \hat{U}^{a} was obtained from the conditions that yield
the (0,2) supersymmetric invariance of the Lagrangian density of the (0,2) U(N)
gauged linear sigma model in superfield formalism. We found that the
consistency conditions for the Abelian gauge group which assure the (0,2)
supersymmetric invariance of Lagrangian density agree with (0,2) chirality
conditions for superpotential. The supermanifold \mathcal{M}^{m|n} becomes the
super weighted complex projective space WCP^{m-1|n} in U(1) case, which is
considered as an example of Calabi-Yau supermanifold.


title:
Supersymmetric N=1 Spin(10) Gauge Theory with Two Spinors via
  a-Maximization

abstract:
  We give a detailed analysis of the superconformal fixed points of
four-dimensional N=1 supersymmetric Spin(10) gauge theory with two spinors and
vectors by using a-maximization procedure.


title: The limit order book on different time scales

abstract:
  Financial markets can be described on several time scales. We use data from
the limit order book of the London Stock Exchange (LSE) to compare how the
fluctuation dominated microstructure crosses over to a more systematic global
behavior.


title: Ground state of the time-independent Gross-Pitaevskii equation

abstract:
  We present a suite of programs to determine the ground state of the
time-independent Gross-Pitaevskii equation, used in the simulation of
Bose-Einstein condensates. The calculation is based on the Optimal Damping
Algorithm, ensuring a fast convergence to the true ground state. Versions are
given for the one-, two-, and three-dimensional equation, using either a
spectral method, well suited for harmonic trapping potentials, or a spatial
grid.


title: Stochastic analysis of an agent-based model

abstract:
  We analyze the dynamics of a forecasting game which exhibits the phenomenon
of information cascades. Each agent aims at correctly predicting a binary
variable and he/she can either look for independent information or herd on the
choice of others. We show that dynamics can be analitically described in terms
of a Langevin equation and its collective behavior is described by the solution
of a Kramers' problem. This provides very accurate results in the region where
the vast majority of agents herd, which corresponds to the most interesting one
from a game theoretic point of view.


title:
Use of a differential pressure transducer for the monitoring of soil
  volume change in cyclic triaxial test on unsaturated soils

abstract:
  A new experimental set-up using a differential pressure transducer was
developed, that enables the monitoring of volume changes in cyclic triaxial
tests on unsaturated soils. Calibration tests were performed in order to
analyze the performance of the set-up, especially in terms of loading
frequencies. Based on calibration results, a low frequency of 0.05 Hz was
adopted for the tests carried out on the unsaturated loess from northern
France. Five water contents were considered in the tests. The obtained results
have confirmed the efficiency of the new system for volume change monitoring
under cyclic loading. The effect of water content on the cyclic behavior of
loess was clearly evidenced. Finally, some suggestions were made to improve the
accuracy of the system.


title: Radiative corrections to co-annihilation processes

abstract:
  In co-annihilation scenarios, the weakly interacting dark matter particle
(WIMP) is close in mass to another particle that can decay into the WIMP. As a
result, both particles freeze out at roughly the same time in the early
universe, and both contribute to the effective dark matter annihilation
cross-section. Since the heavier particle does not need to be weakly
interacting, the co-annihilation processes are in general subject to sizeable
radiative corrections. Here this is analyzed for the example of neutralino-stop
co-annihilation in supersymmetry. The leading QCD corrections are calculated
and it is found that they have a large effect on the effective annihilation
cross-section, reaching more than 50% in some regions of parameter space.


title: Photon Statistics for Single Molecule Non-Linear Spectroscopy

abstract:
  We consider the theory of the non-linear spectroscopy for a single molecule
undergoing stochastic dynamics and interacting with a sequence of two laser
pulses. General expressions for photon counting statistics are obtained, and an
exact solution to the problem of the Kubo-Anderson process is found. In the
limit of impulsive pulses the information on the photon statistics is contained
in the molecule's dipole correlation function. The selective limit where
temporal resolution is maintained, the semi-classical approximation and the
fast modulation limit exhibit general behaviors of this new type of
spectroscopy. We show how the design of the external field leads to rich
insights on dynamics of individual molecules which are different than those
found for an ensemble.


title:
Branching Ratios and CP Asymmetries of B \to a_1(1260) \pi and a_1(1260)
  K Decays

abstract:
  We present the studies of the decays $B\to a_1(1260) \pi$ and $a_1(1260) K$
within the framework of QCD factorization. Due to the G-parity, unlike the
vector meson, the chiral-odd two-parton light-cone distribution amplitudes of
the $a_1$ are antisymmetric under the exchange of quark and anti-quark momentum
fractions in the SU(2) limit. The branching ratios for $a_1 \pi$ modes are
sensitive to tree--penguin interference. The resultant ${\cal B}(B^0 \to
a_1^\pm \pi^\mp)$ are in good agreement with the data. However, using the
current Cabibbo--Kobayashi--Maskawa angles, $\beta=22.0^\circ$ and
$\gamma=59.0^\circ$, our results for the mixing-induced parameter $S$ and
$\alpha_{\rm eff}$ differ from the measurements of the time-dependent CP
asymmetries in the decay $B^0\to a_1^\pm \pi^\mp$ at about the $3.7\sigma$
level. This puzzle may be resolved by using a larger $\gamma \gtrsim 80^\circ$.
For $a_1 K$ modes, the annihilation topologies give sizable contributions and
are sensitive to the first Gegenbauer moment of the leading-twist tensor
(chiral-odd) distribution amplitude of the $a_1$ meson. The $B\to a_1 K$
amplitudes resemble the corresponding $B\to \pi K$ ones very much. Taking the
ratios of corresponding CP-averaged $a_1 K$ and $\pi K$ branching ratios, we
can extract information relevant to the electroweak penguins and annihilations.
The existence of new-physics in the electroweak penguin sector and final state
interactions during decays can thus be explored.


title:
Distances of the bulge globular clusters Terzan 5, Liller 1, UKS 1 and
  Terzan 4 based on HST NICMOS photometry

abstract:
  A large number of pulsars and X-rays sources are detected in globular
clusters. To understand the structure and content of these clusters, accurate
distances are required. We derive the distances of Terzan 5, Liller 1 and UKS 1
using as a reference a recent distance determination of NGC 6528, based on
HST/NICMOS and NTT/SOFI infrared photometry. The distance of the metal-poor
cluster Terzan 4 was derived from a comparison with M92 in NICMOS bands.
Distances of the metal-rich clusters are obtained by comparison of the
Horizontal Branch (HB) level of the clusters, relative to the reddening line
passing through the HB of NGC 6528. We use methods based on NICMOS bands and
transformations to J and H magnitudes with different assumptions. Liller~1 and
Terzan~4 are found to be at the central bulge distance, UKS~1 is beyond the
Galactic center, while Terzan 5 is closer to the Sun than the other four
clusters. The distance of Terzan 5 is of paramount importance, given the impact
of its population of 21 pulsars, which is related to the high cluster density.
The distance of Terzan 5 is found to be d$_{\odot}$=5.5$\pm$0.9 kpc from the
Sun, thus closer to us than values given in studies of pulsars in Terzan 5. As
a consequence, the higher cluster density is even more favourable for formation
of the millisecond pulsars recently detected in this cluster.


title: Dual-Threshold Percolation

abstract:
  For thermoelectric, galvanomagnetic and some other effects there may
simultaneously exist two percolation thresholds, close to which the effective
kinetic coefficients of macroscopically disordered media are critically
dependent on the proximity to percolation thresholds, their behavior being
described by universal critical indexes.


title: The first second of SN1987A neutrino emission

abstract:
  A large fraction of SN1987A electron antineutrino events has been recorded in
the first second. We study how this observation fits into the conventional
paradigm for neutrino emission, and show that there is a 3.2 sigma hint for an
initial accretion phase. This phase involves a large fraction of the energy
emitted in neutrinos and antineutrinos, about 20 % or larger. The occurrence of
neutrino oscillations strengthens these inferences. We discuss why three flavor
oscillations with normal mass hierarchy are completely acceptable, whereas
oscillations with inverted mass hierarchy require more troublesome
interpretations, if theta(13) is above 0.5-1 degrees.


title:
Mapping Nonequilibrium onto Equilibrium: The Macroscopic Fluctuations of
  Simple Transport Models

abstract:
  We study a simple transport model driven out of equilibrium by reservoirs at
the boundaries, corresponding to the hydrodynamic limit of the symmetric simple
exclusion process. We show that a nonlocal transformation of densities and
currents maps the large deviations of the model into those of an open, isolated
chain satisfying detailed balance, where rare fluctuations are the time
reversals of relaxations. We argue that the existence of such a mapping is the
immediate reason why it is possible for this model to obtain an explicit
solution for the large-deviation function of densities through elementary
changes of variables. This approach can be generalized to the other models
previously treated with the macroscopic fluctuation theory.

categories: cond-mat.stat-mech math-ph math.MP nlin.SI


title: The cold gaseous halo of NGC 891

abstract:
  We present HI observations of the edge-on galaxy NGC 891. These are among the
deepest ever performed on an external galaxy. They reveal a huge gaseous halo,
much more extended than seen previously and containing almost 30 % of the HI.
This HI halo shows structures on various scales. On one side, there is a
filament extending (in projection) up to 22 kpc vertically from the disk. Small
(M_HI ~ 10^6 Msol) halo clouds, some with forbidden (apparently
counter-rotating) velocities, are also detected. The overall kinematics of the
halo gas is characterized by differential rotation lagging with respect to that
of the disk. The lag, more pronounced at small radii, increases with height
from the plane. There is evidence that a significant fraction of the halo is
due to a galactic fountain. Accretion from intergalactic space may also play a
role in building up the halo and providing low angular momentum material needed
to account for the observed rotation lag. The long HI filament and the
counter-rotating clouds may be direct evidence of such accretion.


title:
Is the Bardeen-Petterson effect responsible for the warping and
  precession in NGC 4258?

abstract:
  Strong evidence for the presence of a warped Keplerian accretion disc in
NGC4258 (M 106) has been inferred from the kinematics of water masers detected
at sub-parsec scales. Assuming a power-law accretion disc and using constraints
on the disc parameters derived from observational data, we have analyzed the
relativistic Bardeen-Petterson effect driven by a Kerr black hole as the
potential physical mechanism responsible for the disc warping. We found that
the Bardeen-Petterson radius is comparable to or smaller than the inner radius
of the maser disc (independent of the allowed value for the black hole spin
parameter). Numerical simulations for a wide range of physical conditions have
shown that the evolution of a misaligned disc due to the Bardeen-Petterson
torques usually produces an inner flat disc and a warped transition region with
a smooth gradient in the tilt and twist angles. Since this structure is similar
to that seen in NGC 4258, we propose that the Bardeen-Petterson effect may be
responsible for the disc warping in this galaxy. We estimated the time-scale
necessary for the disc inside of the Bardeen-Petterson radius to align with the
black hole's equator, as a function of the black hole spin. Our results show
that the Bardeen-Petterson effect can align the disc within a few billion years
in the case of NGC 4258. Finally, we show that if the observed curvature of the
outer anomalous arms in the galactic disc of NGC 4258 is associated with the
precession of its radio jet/counterjet, then the Bardeen-Petterson effect can
provide the required precession period.


title: Certain aspects of regularity in scalar field cosmological dynamics

abstract:
  We consider dynamics of the FRW Universe with a scalar field. Using
Maupertuis principle we find a curvature of geodesics flow and show that zones
of positive curvature exist for all considered types of scalar field potential.
Usually, phase space of systems with the positive curvature contains islands of
regular motion. We find these islands numerically for shallow scalar field
potentials. It is shown also that beyond the physical domain the islands of
regularity exist for quadratic potentials as well.


title:
An updated survey of globular clusters in M31. II Newly discovered
  bright and remote clusters

abstract:
  We present the first results of a large spectroscopic survey of candidate
globular clusters located in the extreme outskirts of the nearby M31 galaxy. We
obtained low resolution spectra of 48 targets selected from the XSC of 2MASS,
as in Galleti et al. (2005). The observed candidates have been robustly
classified according to their radial velocity and by verifying their
extended/point-source nature from ground-based optical images. Among the 48
observed candidates clusters we found 5 genuine remote globular clusters. One
of them has been already identified independently by Mackey et al. (2007),
their GC1; the other four are completely new discoveries: B516, B517, B518,
B519. The newly discovered clusters lie at projected distance 40 kpc<~R_p<~100
kpc from the center of M31, and have absolute integrated magnitude
-9.5<M_V<-7.5. For all the observed clusters we have measured the strongest
Lick indices and we have obtained spectroscopic metallicity estimates.
Mackey-GC1, Martin-GC1, B517 and B518 have spectra typical of old and metal
poor globular clusters ([Fe/H]<~ -1.3); B519 appears old but quite metal-rich
([Fe/H]~-0.5); B516 presents very strong Balmer absorption lines: if this is
indeed a cluster it should have a relatively young age (likely <2 Gyr). The
present analysis nearly doubles the number of M31 globulars at R_p> 40 kpc. At
odds with the Milky Way, M31 appears to have a significant population of very
bright globular clusters in its extreme outskirts.


title:
Single-photon interferometry with orbital angular momentum circumvents
  standard wave-particle duality

abstract:
  A polarized photon with well-defined orbital angular momentum that emerges
from a Mach-Zehnder interferometer (MZI) is shown to circumvent wave-particle
duality. Its polarization-resolved detection probability forms a non-sinusoidal
interferometric pattern. For certain phase differences between the MZI arms,
this pattern yields both reliable which-path information and high
phase-sensitivity.


title:
SO(3) symmetry between Neel and ferromagnetic order parameters for
  graphene in a magnetic field

abstract:
  I consider the Hubbard model of graphene in an external magnetic field and in
the Hartree-Fock approximation. In the continuum limit, the ground state energy
at half filling becomes nearly symmetric under rotations of the three-component
vector (N1,N2,m), with the first two components representing the Neel order
parameter orthogonal to and the third component the magnetization parallel with
the external magnetic field. When the symmetry breaking effects arising from
the lattice, Zeeman coupling, and higher Landau levels are included the system
develops a quantum critical point at which the antiferromagnetic order
disappears and the magnetization has a kink. The observed incompressible state
at filling factor one is argued to arise due to a finite third component of the
Neel order parameter at these electron densities. Recent experiments appear
consistent with vanishing N1 and N2, and finite N3, at the filling factors zero
and one, respectively.


title: Many-body theory of excitation dynamics in an ultracold Rydberg gas

abstract:
  We develop a theoretical approach for the dynamics of Rydberg excitations in
ultracold gases, with a realistically large number of atoms. We rely on the
reduction of the single-atom Bloch equations to rate equations, which is
possible under various experimentally relevant conditions. Here, we explicitly
refer to a two-step excitation-scheme. We discuss the conditions under which
our approach is valid by comparing the results with the solution of the exact
quantum master equation for two interacting atoms. Concerning the emergence of
an excitation blockade in a Rydberg gas, our results are in qualitative
agreement with experiment. Possible sources of quantitative discrepancy are
carefully examined. Based on the two-step excitation scheme, we predict the
occurrence of an antiblockade effect and propose possible ways to detect this
excitation enhancement experimentally in an optical lattice as well as in the
gas phase.


title:
Influence of the lattice topography on a three-dimensional, controllable
  Brownian motor

abstract:
  We study the influence of the lattice topography and the coupling between
motion in different directions, for a three-dimensional Brownian motor based on
cold atoms in a double optical lattice. Due to controllable relative spatial
phases between the lattices, our Brownian motor can induce drifts in arbitrary
directions. Since the lattices couple the different directions, the relation
between the phase shifts and the directionality of the induced drift is non
trivial. Here is therefore this relation investigated experimentally by
systematically varying the relative spatial phase in two dimensions, while
monitoring the vertically induced drift and the temperature. A relative spatial
phase range of 2pi x 2pi is covered. We show that a drift, controllable both in
speed and direction, can be achieved, by varying the phase both parallel and
perpendicular to the direction of the measured induced drift. The experimental
results are qualitatively reproduced by numerical simulations of a simplified,
classical model of the system.


title: Criticality and Condensation in a Non-Conserving Zero Range Process

abstract:
  The Zero-Range Process, in which particles hop between sites on a lattice
under conserving dynamics, is a prototypical model for studying real-space
condensation. Within this model the system is critical only at the transition
point. Here we consider a non-conserving Zero-Range Process which is shown to
exhibit generic critical phases which exist in a range of creation and
annihilation parameters. The model also exhibits phases characterised by
mesocondensates each of which contains a subextensive number of particles. A
detailed phase diagram, delineating the various phases, is derived.


title: Field-theoretical formulations of MOND-like gravity

abstract:
  Modified Newtonian dynamics (MOND) is a possible way to explain the flat
galaxy rotation curves without invoking the existence of dark matter. It is
however quite difficult to predict such a phenomenology in a consistent field
theory, free of instabilities and admitting a well-posed Cauchy problem. We
examine critically various proposals of the literature, and underline their
successes and failures both from the experimental and the field-theoretical
viewpoints. We exhibit new difficulties in both cases, and point out the hidden
fine tuning of some models. On the other hand, we show that several published
no-go theorems are based on hypotheses which may be unnecessary, so that the
space of possible models is a priori larger. We examine a new route to
reproduce the MOND physics, in which the field equations are particularly
simple outside matter. However, the analysis of the field equations within
matter (a crucial point which is often forgotten in the literature) exhibits a
deadly problem, namely that they do not remain always hyperbolic. Incidentally,
we prove that the same theoretical framework provides a stable and well-posed
model able to reproduce the Pioneer anomaly without spoiling any of the
precision tests of general relativity. Our conclusion is that all MOND-like
models proposed in the literature, including the new ones examined in this
paper, present serious difficulties: Not only they are unnaturally fine tuned,
but they also fail to reproduce some experimental facts or are unstable or
inconsistent as field theories. However, some frameworks, notably the
tensor-vector-scalar (TeVeS) one of Bekenstein and Sanders, seem more promising
than others, and our discussion underlines in which directions one should try
to improve them.


title: Nature of phase transition in magnetic thin films

abstract:
  We study the critical behavior of magnetic thin films as a function of the
film thickness. We use the ferromagnetic Ising model with the high-resolution
multiple histogram Monte Carlo (MC) simulation. We show that though the 2D
behavior remains dominant at small thicknesses, there is a systematic
continuous deviation of the critical exponents from their 2D values. We observe
that in the same range of varying thickness the deviation of the exponent $\nu$
is very small from its 2D value, while exponent $\beta$ suffers a larger
deviation. Moreover, as long as the film thickness is fixed, i. e. no finite
size scaling is done in the $z$ direction perpendicular to the film, the 3D
values of the critical exponents cannot be attained even with very large (but
fixed) thickness. The crossover to 3D universality class cannot therefore take
place without finite size scaling applied in the $z$ direction, in the limit of
numerically accessible thicknesses. From values of exponent $\alpha$ obtained
by MC, we estimate the effective dimension of the system. We conclude that with
regard to the critical behavior, thin films behave as systems with effective
dimension between 2 and 3.


title:
The use of the logarithm of the variate in the calculation of
  differential entropy among certain related statistical distributions

abstract:
  This paper demonstrates that basic statistics (mean, variance) of the
logarithm of the variate itself can be used in the calculation of differential
entropy among random variables known to be multiples and powers of a common
underlying variate. For the same set of distributions, the variance of the
differential self-information is shown also to be a function of statistics of
the logarithmic variate. Then entropy and its "variance" can be estimated using
only statistics of the logarithmic variate plus constants, without reference to
the traditional parameters of the variate.


title: Meson-baryon sigma terms in QCD Sum Rules

abstract:
  We evaluate the pion-nucleon and the pion-Delta sigma terms by employing the
method of quantum chromodynamics (QCD) sum rules. The obtained value of the
pion-nucleon sigma term is compatible with the larger values already
anticipated by the recent calculations. It is also found that the pion-Delta
sigma term is as large as the pion-nucleon sigma term.


title: p-adic logarithms for polynomial dynamics

abstract:
  We prove a dynamical version of the Mordell-Lang conjecture for subvarieties
of the affine space A^g over a p-adic field, endowed with polynomial actions on
each coordinate of A^g. We use analytic methods similar to the ones employed by
Skolem, Chabauty, and Coleman for studying diophantine equations.


title: The K\"ahler-Ricci flow and the $\bar\partial$ operator on vector fields

abstract:
  The limiting behavior of the normalized K\"ahler-Ricci flow for manifolds
with positive first Chern class is examined under certain stability conditions.
First, it is shown that if the Mabuchi K-energy is bounded from below, then the
scalar curvature converges uniformly to a constant. Second, it is shown that if
the Mabuchi K-energy is bounded from below and if the lowest positive
eigenvalue of the $\bar\partial^\dagger \bar\partial$ operator on smooth vector
fields is bounded away from 0 along the flow, then the metrics converge
exponentially fast in $C^\infty$ to a K\"ahler-Einstein metric.


title:
Beyond Geometrical Optics and Bohmian Physics: A New Exact and
  Deterministic Hamiltonian Approach to Wave-Like Features in Classical and
  Quantum Physics

abstract:
  The indeterministic character of physical laws is generally considered to be
the most important consequence of quantum physics. A deterministic point of
view, however, together with the possibility of well defined Hamiltonian
trajectories, emerges as the most natural one from the analysis of the
time-independent Helmholtz-like equations encountered both in Classical
Electromagnetism and in Wave Mechanics. In the case of particle beams a
suitable pattern of trajectories is provided (for any set of boundary
conditions) by a set of dynamical laws containing the classical ones as a
simple limiting case.


title: Anomaly cancellation in three-dimensional noncommutative gauge theories

abstract:
  The anomaly found by Callan and Harvey is shown to be cancelled in a
three-dimensional noncommutative gauge theory coupled to a fermion with a mass
function depending on one spatial coordinate (domain wall mass). This
evaluation has been done for the fermion in the fundamental and adjoint
representations of the gauge group in the limit of small noncommutativity
$\theta$ parameter.


title:
Experimental Approach to Stellar Reactions with RI Beams - Overview of
  Experiments on Hydrogen Burning -

abstract:
  After a short review on resent developments achieved in astrophysics in the
past years since last NN conference, experimental efforts in nuclear
astrophysics primarily with RI beams were revisited, especially on the works
relevant to neutron-deficient nuclei, the other half of the nuclear chart
reviewed by Rehm in this conference. A new interesting recognition discussed in
the past years is the important role of explosive hydrogen burning process in
the very early stage of type II supernovae. A new broadening research field
related to the first generation stars both from observations as well as from
nuclear astrophysics was also discussed.


title:
Calculations of ${\cal O}(p^6)$ Resonance Coupling Constants in the
  Scalar Sector of the ENJL Model

abstract:
  We derive the scalar resonance coupling constants of resonance chiral theory
from the Extended Nambu Jona-Lasinio model by using heat-kernel expansion.


title:
ARCRAIDER I: Detailed optical and X-ray analysis of the cooling flow
  cluster Z3146

abstract:
  We present a detailed analysis of the medium redshift (z=0.2906) galaxy
cluster Z3146 which is part of the ongoing ARCRAIDER project, a systematic
search for gravitational arcs in massive clusters of galaxies. The analysis of
Z3146 is based on deep optical wide field observations in the B, V and R bands
obtained with the WFI@ESO2.2m, and shallow archival WFPC2@HST taken with the
F606W filter, which are used for strong as well as weak lensing analyses.
Additionally we have used publicly available XMM/Newton observations for a
detailed X-ray analysis of Z3146. Both methods, lensing and X-ray, were used to
determine the dynamical state and to estimate the total mass. We also
identified four gravitational arc candidates. We find this cluster to be in a
relaxed state, which is confirmed by a large cooling flow with nominal
~1600M_\odot per year, regular galaxy density and light distributions and a
regular shape of the weak lensing mass reconstruction. The mass content derived
with the different methods agrees well within 25% at r_{200}=1661
h_{70}^{-1}kpc indicating a velocity dispersion of
\sigma_v=869^{+124}_{-153}km/s.


title: Distortion in Groups of Circle and Surface Diffeomorphisms

abstract:
  In these lectures we consider how algebraic properties of discrete subgroups
of Lie groups restrict the possible actions of those groups on surfaces. The
results show a strong parallel between the possible actions of such a group on
the circle $S^1$ and the measure preserving actions on surfaces.
  Our aim is the study of the (non)-existence of actions of lattices in a large
class of non-compact Lie groups on surfaces. A definitive analysis of the
analogous question for actions on $S^1$ was carried out by \'E. Ghys. Our
approach is topological and insofar as possible we try to isolate properties of
a group which provide the tools necessary for our analysis. The two key
properties we consider are almost simplicity and the existence of a distortion
element. Both will be defined and described in the lectures.
  Our techniques are almost all from low dimensional dynamics. But we are
interested in how algebraic properties of a group -- commutativity, nilpotence,
etc. affect the possible kinds of dynamics which can occur. For most of the
results we will consider groups of diffeomorphisms which preserve a Borel
probability measure.


title:
Energetics, skeletal dynamics and long-term predictions in
  Kolmogorov-Lorenz systems

abstract:
  We study a particular return map for a class of low dimensional chaotic
models called Kolmogorov Lorenz systems, which received an elegant general
Hamiltonian description and includes also the famous Lorenz63 case, from the
viewpoint of energy and Casimir balance. In particular it is considered in
detail a subclass of these models, precisely those obtained from the Lorenz63
by a small perturbation on the standard parameters, which includes for example
the forced Lorenz case in Ref.[6]. The paper is divided into two parts. In the
first part the extremes of the mentioned state functions are considered, which
define an invariant manifold, used to construct an appropriate Poincare surface
for our return map. From the experimental observation of the simple orbital
motion around the two unstable fixed points, together with the circumstance
that these orbits are classified by their energy or Casimir maximum, we
construct a conceptually simple skeletal dynamics valid within our sub class,
reproducing quite well the Lorenz map for Casimir. This energetic approach
sheds some light on the physical mechanism underlying regime transitions. The
second part of the paper is devoted to the investigation of a new type of
maximum energy based long term predictions, by which the knowledge of a
particular maximum energy shell amounts to the knowledge of the future
(qualitative) behaviour of the system. It is shown that, in this respect, a
local analysis of predictability is not appropriate for a complete
characterization of this behaviour. A perspective on the possible extensions of
this type of predictability analysis to more realistic cases in (geo)fluid
dynamics is discussed at the end of the paper.


title:
An Experiment to Search for Light Dark Matter in Low-Energy ep
  Scattering

abstract:
  Anomalous production of low-energy photons from the galactic center have
fueled speculations on the nature and properties of dark matter particles. In
particular, it has been proposed that light scalars may be responsible for the
bulk of the matter density of the universe, and that they couple to ordinary
matter through a light spin-1 boson. If this is the case, then such particles
may be produced in the quasi-elastic low-energy scattering of electrons off
protons. We present a proposal for an experiment to search for this process and
assess its viability.


title: Poncelet pairs and the Twist Map associated to the Poncelet Billiard

abstract:
  We show that for a fixed curve $K$ and for a family of variables curves $L$,
the number of $n$-Poncelet pairs is $\frac{e (n)}{2}$, where $e(n)$ is the
number of natural numbers $m$ smaller than $n$ and which satisfies mcd $
(m,n)=1$. The curvee $K$ do not have to be part of the family.
  In order to show this result we consider an associated billiard
transformation and a twist map which preserves area.
  We use Aubry-Mather theory and the rotation number of invariant curves to
obtain our main result.
  In the last section we estimate the derivative of the rotation number of a
general twist map using some properties of the continued fraction expansion .


title: On the Spectrum of the Dirichlet Laplacian in a Narrow Strip

abstract:
  We derive a two-terms asymptotics for eigenvalues of the Dirichlet Laplacian
in a narrow strip of variable width. The asymptotics is taken with respect to a
small paprameter that characterizes the width of the strip.


title: Grand Unification with and without Supersymmetry

abstract:
  Grand Unified Theories based on the group SO(10) generically provide
interesting and testable relations between the charged fermions and neutrino
sector masses and mixings. In the light of the recent neutrino data, we
reexamine these relations both in supersymmetric and non-supersymmetric models,
and give a brief review of their present status.


title: C*- Algebras and Thermodynamic Formalism

abstract:
  We present a detailed exposition (for a Dynamical System audience) of the
content of the paper: R. Exel and A. Lopes, $C^*$ Algebras, approximately
proper equivalence relations and Thermodynamic Formalism, {\it Erg. Theo. and
Dyn. Syst.}, Vol 24, pp 1051-1082 (2004). We show only the uniqueness of the
\beta-KMS (in a certain C*-Algebra obtained from the operators acting in $L^2$
of a Gibbs invariant probability $\mu$) and its relation with the
eigen-probability $\nu_\beta$ for the dual of a certain Ruele operator. We
consider an example for a case of Hofbauer type where there exist a Phase
transition for the Gibbs state. There is no Phase transition for the KMS state.


title:
High energy afterglows and flares from Gamma-Ray Burst by Inverse
  Compton emission

abstract:
  We perform a detailed study of inverse Compton (IC) emission for a fireball
undergoing external shock (ES) in either a uniform or a wind-like interstellar
medium, and assess the relative importance of IC and synchrotron emissions. We
determine the primary model parameters driving the IC to synchrotron emission
ratio in the case of a short duration central engine. We then investigate the
case of ES by a long duration central engine, or delayed external shock (DES),
a model that can account for some of the flares observed in GRB X-ray light
curves. We present model predictions, in particular in terms of GeV vs X-ray
behavior, and compare them with other models proposed to explain the origin of
flares. We find that if most of the emission occurs when the fireball is in the
fast cooling regime, then a substantial GeV emission is expected both for a
short (standard ES) and a long (DES) duration central engine activity. In
particular, in the context of standard ES we are able to account for the
delayed emission observed in GRB940217. In the case of DES, we find that IC
scattering of X-ray flare photons can produce high energy flares in the GeV
band, which can be detected by GLAST. The detectability of high energy flares
improves with the burst kinetic energy: about 30% of Swift GRBs showing flares
in their X-ray light curve have sufficiently large kinetic energy so that the
expected high flares can be detected by GLAST. One important prediction of the
DES model is the simultaneity between low and high energy flares. To test this
simultaneity, the peak energies of both flares need to fall below or within the
observational bands. We predict that X-ray flares with peak energy of ~10 eV
produce high energy flares with peak energy of around 100 MeV-GeV. Observations
by Swift and GLAST then, can test the predicted simultaneity.


title:
The Hypercube of Life: How Protein Stability Imposes Limits on Organism
  Complexity and Speed of Molecular Evolution

abstract:
  Classical population genetics a priori assigns fitness to alleles without
considering molecular or functional properties of proteins that these alleles
encode. Here we study population dynamics in a model where fitness can be
inferred from physical properties of proteins under a physiological assumption
that loss of stability of any protein encoded by an essential gene confers a
lethal phenotype. Accumulation of mutations in organisms containing Gamma genes
can then be represented as diffusion within the Gamma dimensional hypercube
with adsorbing boundaries which are determined, in each dimension, by loss of a
protein stability and, at higher stability, by lack of protein sequences.
Solving the diffusion equation whose parameters are derived from the data on
point mutations in proteins, we determine a universal distribution of protein
stabilities, in agreement with existing data. The theory provides a fundamental
relation between mutation rate, maximal genome size and thermodynamic response
of proteins to point mutations. It establishes a universal speed limit on rate
of molecular evolution by predicting that populations go extinct (via lethal
mutagenesis) when mutation rate exceeds approximately 6 mutations per essential
part of genome per replication for mesophilic organisms and 1 to 2 mutations
per genome per replication for thermophilic ones. Further, our results suggest
that in absence of error correction, modern RNA viruses and primordial genomes
must necessarily be very short. Several RNA viruses function close to the
evolutionary speed limit while error correction mechanisms used by DNA viruses
and non-mutant strains of bacteria featuring various genome lengths and
mutation rates have brought these organisms universally about 1000 fold below
the natural speed limit.


title:
Comment on "Removable singularities for solutions of coupled
  Yang-Mills-Dirac equations" [J. Math. Phys. 47, 103502 (2006)]

abstract:
  A lemma from elliptic theory is used to improve a recent result by Li
concerning the removability of an isolated point singularity from solutions of
the coupled Yang-Mills-Dirac equations.


title: On Term Rewriting Systems Having a Rational Derivation

abstract:
  Several types of term rewriting systems can be distinguished by the way their
rules overlap. In particular, we define the classes of prefix, suffix,
bottom-up and top-down systems, which generalize similar classes on words. Our
aim is to study the derivation relation of such systems (i.e. the reflexive and
transitive closure of their rewriting relation) and, if possible, to provide a
finite mechanism characterizing it. Using a notion of rational relations based
on finite graph grammars, we show that the derivation of any bottom-up,
top-down or suffix systems is rational, while it can be non recursive for
prefix systems.


title: Preparing an ESO proposal

abstract:
  Preparing observing proposals is a classical exercise in an observational
astronomer's life. In this paper, we summarize the general requirements to
write a good proposal for the ESO telescopes, and eventually obtain telescope
time. We detail in particular the different proposal types, how they are
evaluated by ESO, what they should contain and what to avoid. The advice given
in the present paper are applicable to observing proposals for the AMBER and
MIDI instruments of the VLTI, but also to other ESO instruments, and to some
extent to other observatories.


title:
Can a charged dust ball be sent through the Reissner--Nordstr\"{o}m
  wormhole?

abstract:
  In a previous paper we formulated a set of necessary conditions for the
spherically symmetric weakly charged dust to avoid Big Bang/Big Crunch, shell
crossing and permanent central singularities. However, we did not discuss the
properties of the energy density, some of which are surprising and seem not to
have been known up to now. A singularity of infinite energy density does exist
-- it is a point singularity situated on the world line of the center of
symmetry. The condition that no mass shell collapses to $R = 0$ if it had $R >
0$ initially thus turns out to be still insufficient for avoiding a
singularity. Moreover, at the singularity the energy density $\epsilon$ is
direction-dependent: $\epsilon \to - \infty$ when we approach the singular
point along a $t =$ const hypersurface and $\epsilon \to + \infty$ when we
approach that point along the center of symmetry. The appearance of
negative-energy-density regions turns out to be inevitable. We discuss various
aspects of this property of our configuration. We also show that a permanently
pulsating configuration, with the period of pulsation independent of mass, is
possible only if there exists a permanent central singularity.


title: The Complexity of Quantum Systems on a One-dimensional Chain

abstract:
  We prove that adiabatic computation is equivalent to standard quantum
computation even when the adiabatic quantum system is restricted to be a set of
particles on a one-dimensional chain. We give a construction that uses a
2-local Hamiltonian on nearest neighbors using particles that can have ten
distinct states. This implies a construction of a one-dimensional chain of
qubits in which the Hamiltonian is 6-local. We adapt this construction to show
that the 2-local Hamiltonian for 13-state particles is QMA-complete which in
turn implies that the 8-local Hamiltonian restricted to a one-dimensional chain
of qubits is QMA-complete.


title: Semidefinite Representation of Convex Sets

abstract:
  Let $S =\{x\in \re^n: g_1(x)\geq 0, ..., g_m(x)\geq 0\}$ be a semialgebraic
set defined by multivariate polynomials $g_i(x)$. Assume $S$ is convex, compact
and has nonempty interior. Let $S_i =\{x\in \re^n: g_i(x)\geq 0\}$, and $\bdS$
(resp. $\bdS_i$) be the boundary of $S$ (resp. $S_i$). This paper discusses
whether $S$ can be represented as the projection of some LMI representable set.
Such $S$ is called semidefinite representable or SDP representable. The
contributions of this paper: {\bf (i)} Assume $g_i(x)$ are all concave on $S$.
If the positive definite Lagrange Hessian (PDLH) condition holds, i.e., the
Hessian of the Lagrange function for optimization problem of minimizing any
nonzero linear function $\ell^Tx$ on $S$ is positive definite at the minimizer,
then $S$ is SDP representable. {\bf (ii)} If each $g_i(x)$ is either
sos-concave ($-\nabla^2g_i(x)=W(x)^TW(x)$ for some possibly nonsquare matrix
polynomial $W(x)$) or strictly quasi-concave on $S$, then $S$ is SDP
representable. {\bf (iii)} If each $S_i$ is either sos-convex or poscurv-convex
($S_i$ is compact convex, whose boundary has positive curvature and is
nonsingular, i.e. $\nabla g_i(x) \not = 0$ on $\bdS_i \cap S$), then $S$ is SDP
representable. This also holds for $S_i$ for which $\bdS_i \cap S$ extends
smoothly to the boundary of a poscurv-convex set containing $S$. {\bf (iv)} We
give the complexity of Schm\"{u}dgen and Putinar's matrix Positivstellensatz,
which are critical to the proofs of (i)-(iii).


title: Ab Initio Study of 40Ca with an Importance Truncated No-Core Shell Model

abstract:
  We propose an importance truncation scheme for the no-core shell model, which
enables converged calculations for nuclei well beyond the p-shell. It is based
on an a priori measure for the importance of individual basis states
constructed by means of many-body perturbation theory. Only the physically
relevant states of the no-core model space are considered, which leads to a
dramatic reduction of the basis dimension. We analyze the validity and
efficiency of this truncation scheme using different realistic nucleon-nucleon
interactions and compare to conventional no-core shell model calculations for
4He and 16O. Then, we present the first converged calculations for the ground
state of 40Ca within no-core model spaces including up to
16\hbar\Omega-excitations using realistic low-momentum interactions. The scheme
is universal and can be easily applied to other quantum many-body problems.


title: SNO+: predictions from standard solar models and spin flavour precession

abstract:
  Time variability of the solar neutrino flux especially in the low and
intermediate energy sector remains an open question and, if it exists, it is
likely to be originated from the magnetic moment transition from active to
light sterile neutrinos at times of intense solar activity and magnetic field.
We examine the prospects for the SNO+ experiment to address this important
issue and to distinguish between the two classes of solar models which are
currently identified as corresponding to a high (SSM I) and a low (SSM II)
heavy element abundance. We also evaluate the predictions from these two models
for the Chlorine experiment event rate in the standard LMA and LMA+Spin Flavour
Precession (SFP) scenarios. It is found that after three years of SNO+ data
taking, the pep flux measurement will be able to discriminate between the
standard LMA and LMA+SFP scenarios, independently of which is the correct solar
model. If the LMA rate is measured, SFP with $B_0 \sim 280kG$ for the resonant
$\Delta m^2_{01}$ can be excluded at more than $4\sigma$. A low rate would
signal new physics, excluding all the 90% allowed range of the standard LMA
solution at 3$\sigma$, and a time variability would be a strong signature of
the SFP model. The CNO fluxes are the ones for which the two SSM predictions
exhibit the largest differences, so their measurement at SNO+ will be important
to favour one or the other. The distinction will be clearer after LMA or SFP
are confirmed with pep, but still, a CNO measurement at the level of SSM I/LMA
will disfavour SSM II at about $3 \sigma$. We conclude that consistency between
future pep and CNO flux measurements at SNO+ and Chlorine would either favour
an LMA+SFP scenario or favour SSM II over SSM I.


title: A sufficient condition for Gaussian departure in turbulence

abstract:
  The interaction of two isotropic turbulent fields of equal integral scale but
different kinetic energy generates the simplest kind of inhomogeneous turbulent
field. In this paper we present a numerical experiment where two time decaying
isotropic fields of kinetic energies $E_1$ and $E_2$ initially match over a
narrow region. Within this region the kinetic energy varies as a hyperbolic
tangent. The following temporal evolution produces a shearless mixing. The
anisotropy and intermittency of velocity and velocity derivative statistics is
observed. In particular the asymptotic behavior in time and as a function of
the energy ratio $E_1/E_2 \to \infty$ is discussed. This limit corresponds to
the maximum observable turbulent energy gradient for a given $E_1$ and is
obtained through the limit $E_2 \to 0$. A field with $E_1/E_2 \to \infty$
represents a mixing which could be observed near a surface subject to a very
small velocity gradient separating two turbulent fields, one of which is nearly
quiescent. In this condition the turbulent penetration is maximum and reaches a
value equal to 1.2 times the nominal mixing layer width. The experiment shows
that the presence of a turbulent energy gradient is sufficient for the
appearance of intermittency and that during the mixing process the pressure
transport is not negligible with respect to the turbulent velocity transport.
These findings may open the way to the hypothesis that the presence of a
gradient of turbulent energy is the minimal requirement for Gaussian departure
in turbulence.


title: Quantum Lifetime of Two-Dimensional Holes

abstract:
  The quantum lifetime of two-dimensional holes in a GaAs/AlGaAs double quantum
well is determined via tunneling spectroscopy. At low temperatures the lifetime
is limited by impurity scattering but at higher temperatures hole-hole Coulomb
scattering dominates. Our results are consistent with Fermi liquid theory, at
least up to r_s = 11. At the highest temperatures the measured width of the
hole spectral function becomes comparable to the Fermi energy. A new,
tunneling-spectroscopic, method for determining the in-plane effective mass of
the holes is also demonstrated.


title:
Quasi-linear dynamics in nonlinear Schr\" odinger equation with periodic
  boundary conditions

abstract:
  It is shown that a large subset of initial data with finite energy ($L^2$
norm)evolves nearly linearly in nonlinear Schr\" odinger equation with periodic
boundary conditions. These new solutions are not perturbations of the known
ones such as solitons, semiclassical or weakly linear solutions.


title:
Solving ill-conditioned linear algebraic systems by the dynamical
  systems method (DSM)

abstract:
  An iterative scheme for the Dynamical Systems Method (DSM) is given such that
one does not have to solve the Cauchy problem occuring in the application of
the DSM for solving ill-conditioned linear algebraic systems. The novelty of
the algorithm is that the algorithm does not have to find the regularization
parameter $a$ by solving a nonlinear equation. Numerical experiments show that
DSM competes favorably with the Variational Regularization.


title:
$WZ$ Production at $e\gamma$ Colliders and Anomalous Quartic $WWZ\gamma$
  Coupling

abstract:
  We investigate the constraints on the anomalous quartic $W^{+}W^{-}Z\gamma$
gauge boson coupling through the process $e^{-}\gamma\to \nu_{e}W^{-}Z$.
Considering incoming beam polarizations and the longitudinal and transverse
polarization states of the final W and Z boson we find 95% confidence level
limits on the anomalous coupling parameter $a_{n}$ with an integrated
luminosity of 500 $fb^{-1}$ and $\sqrt{s}$=0.5, 1 TeV energies. We show that
initial beam and final state polarizations improve the sensitivity to the
anomalous coupling by up to factors of 2 - 3.5 depending on the energy.


title: Information-flux approach to multiple-spin dynamics

abstract:
  We introduce and formalize the concept of information flux in a many-body
register as the influence that the dynamics of a specific element receive from
any other element of the register. By quantifying the information flux in a
protocol, we can design the most appropriate initial state of the system and,
noticeably, the distribution of coupling strengths among the parts of the
register itself. The intuitive nature of this tool and its flexibility, which
allow for easily manageable numerical approaches when analytic expressions are
not straightforward, are greatly useful in interacting many-body systems such
as quantum spin chains. We illustrate the use of this concept in quantum
cloning and quantum state transfer and we also sketch its extension to
non-unitary dynamics.


title: The power of quantum systems on a line

abstract:
  We study the computational strength of quantum particles (each of finite
dimensionality) arranged on a line. First, we prove that it is possible to
perform universal adiabatic quantum computation using a one-dimensional quantum
system (with 9 states per particle). This might have practical implications for
experimentalists interested in constructing an adiabatic quantum computer.
Building on the same construction, but with some additional technical effort
and 12 states per particle, we show that the problem of approximating the
ground state energy of a system composed of a line of quantum particles is
QMA-complete; QMA is a quantum analogue of NP. This is in striking contrast to
the fact that the analogous classical problem, namely, one-dimensional
MAX-2-SAT with nearest neighbor constraints, is in P. The proof of the
QMA-completeness result requires an additional idea beyond the usual techniques
in the area: Not all illegal configurations can be ruled out by local checks,
so instead we rule out such illegal configurations because they would, in the
future, evolve into a state which can be seen locally to be illegal. Our
construction implies (assuming the quantum Church-Turing thesis and that
quantum computers cannot efficiently solve QMA-complete problems) that there
are one-dimensional systems which take an exponential time to relax to their
ground states at any temperature, making them candidates for being
one-dimensional spin glasses.


title: On canonical bases and internality criteria

abstract:
  A criterion is given for a type in a finite rank stable theory to be (almost)
internal to a given nonmodular minimal type. The motivation comes from results
of Campana which give criteria for compact complex analytic spaces to be
algebraic (namely Moishezon), in terms of the existence of "generating"
families of algebraic subvarieties. A model-theoretic anologue/generalisation
of Campana's results is given under the hypothesis that the theory has the
"canonical base property" (CBP), a property that is conjectured to hold in all
stable finite rank theories and which states that the type of the canonical
base over a realisation is almost internal to the minimal types of the theory.


title: Molecular Clock on a Neutral Network

abstract:
  The number of fixed mutations accumulated in an evolving population often
displays a variance that is significantly larger than the mean (the
overdispersed molecular clock). By examining a generic evolutionary process on
a neutral network of high-fitness genotypes, we establish a formalism for
computing all cumulants of the full probability distribution of accumulated
mutations in terms of graph properties of the neutral network, and use the
formalism to prove overdispersion of the molecular clock. We further show that
significant overdispersion arises naturally in evolution when the neutral
network is highly sparse, exhibits large global fluctuations in neutrality, and
small local fluctuations in neutrality. The results are also relevant for
elucidating the topological structure of a neutral network from empirical
measurements of the substitution process.


title: Aperiodic substitutional systems and their Bratteli diagrams

abstract:
  In the paper we study aperiodic substitutional dynamical systems arisen from
non-primitive substitutions.
  We prove that the Vershik homeomorphism $\phi$ of a stationary ordered
Bratteli diagram is homeomorphic to an aperiodic substitutional system if and
only if no restriction of $\phi$ to a minimal component is homeomorphic to an
odometer. We also show that every aperiodic substitutional system generated by
a substitution with nesting property is homeomorphic to the Vershik map of a
stationary ordered Bratteli diagram. It is proved that every aperiodic
substitutional system is recognizable. The classes of $m$-primitive
substitutions and associated to them derivative substitutions are studied. We
discuss also the notion of expansiveness for Cantor dynamical systems of finite
rank.


title: Examples of Free Actions on Products of Spheres

abstract:
  We construct a non-abelian extension $\Gamma$ of $S^1$ by $\cy 3 \times \cy
3$, and prove that $\Gamma$ acts freely and smoothly on $S^{5} \times S^{5}$.
This gives new actions on $S^{5} \times S^{5}$ for an infinite family $\cP$ of
finite 3-groups. We also show that any finite odd order subgroup of the
exceptional Lie group $G_2$ admits a free smooth action on $S^{11}\times
S^{11}$. This gives new actions on $S^{11}\times S^{11}$ for an infinite family
$\cE $ of finite groups. We explain the significance of these families $\cP $,
$\cE $ for the general existence problem, and correct some mistakes in the
literature.


title: Chern-Simons AdS_5 supergravity in a Randall-Sundrum background

abstract:
  Chern-Simons AdS supergravity theories are gauge theories for the super-AdS
group. These theories possess a fermionic symmetry which differs from standard
supersymmetry. In this paper, we study five-dimensional Chern-Simons AdS
supergravity in a Randall-Sundrum scenario with two Minkowski 3-branes. After
making modifications to the D = 5 Chern-Simons AdS supergravity action and
fermionic symmetry transformations, we obtain a Z_2-invariant total action S =
\tilde{S}_bulk + S_brane and fermionic transformations \tilde{\delta}_\epsilon.
While \tilde{\delta}_\epsilon \tilde{S}_bulk = 0, the fermionic symmetry is
broken by S_brane. Our total action reduces to the original Randall-Sundrum
model when \tilde{S}_bulk is restricted to its gravitational sector. We solve
the Killing spinor equations for a bosonic configuration with vanishing su(N)
and u(1) gauge fields.


title: Full Counting Statistics and Field Theory

abstract:
  We review the relations between the full counting statistics and the field
theory of electric circuits. We demonstrate that for large conductances the
counting statistics is determined by non-trivial saddle-point of the field.
Coulomb effects in this limit are presented as quantum corrections that can
stongly renormalize the action at low energies.


title: Comment on "Regularizing capacity of metabolic networks"

abstract:
  In a recent paper, Marr, Muller-Linow and Hutt [Phys. Rev. E 75, 041917
(2007)] investigate an artificial dynamic system on metabolic networks. They
find a less complex time evolution of this dynamic system in real networks,
compared to networks of reference models. The authors argue that this suggests
that metabolic network structure is a major factor behind the stability of
biochemical steady states. We reanalyze the same kind of data using a dynamic
system modeling actual reaction kinetics. The conclusions about stability, from
our analysis, are inconsistent with those of Marr et al. We argue that this
issue calls for a more detailed type of modeling.


title: The Distance Geometry of Music

abstract:
  We demonstrate relationships between the classic Euclidean algorithm and many
other fields of study, particularly in the context of music and distance
geometry. Specifically, we show how the structure of the Euclidean algorithm
defines a family of rhythms which encompass over forty timelines
(\emph{ostinatos}) from traditional world music. We prove that these
\emph{Euclidean rhythms} have the mathematical property that their onset
patterns are distributed as evenly as possible: they maximize the sum of the
Euclidean distances between all pairs of onsets, viewing onsets as points on a
circle. Indeed, Euclidean rhythms are the unique rhythms that maximize this
notion of \emph{evenness}. We also show that essentially all Euclidean rhythms
are \emph{deep}: each distinct distance between onsets occurs with a unique
multiplicity, and these multiplicies form an interval $1,2,...,k-1$. Finally,
we characterize all deep rhythms, showing that they form a subclass of
generated rhythms, which in turn proves a useful property called shelling. All
of our results for musical rhythms apply equally well to musical scales. In
addition, many of the problems we explore are interesting in their own right as
distance geometry problems on the circle; some of the same problems were
explored by Erd\H{o}s in the plane.


title:
Detailed Spectral Analysis of the Type Ib Supernova 1999dn. Paper I:
  Hydrogen-free Models

abstract:
  We present spectral fits to five epochs of the typical Type Ib supernova
1999dn using the generalized, non-LTE, stellar atmospheres code PHOENIX. Our
goal is threefold: to determine basic physical properties of the supernova
ejecta, such as velocity, temperature, and density gradients; to reproduce He I
absorption lines by invoking non-thermal excitation; and, to investigate
possible spectral signatures of hydrogen, especially a feature around 6200
Angstrom, which has been attributed to high velocity $H_\alpha$. Our models
assume an atmosphere with uniform composition devoid of any hydrogen. Our model
spectra fit the observed spectra well, successfully reproducing most of the
features, including the prominent He I absorptions. The most plausible
alternative to $H_\alpha$ as the source of the 6200 Angstrom feature is a blend
of Fe II and Si II lines, which can be made stronger to fit the observed
feature better by increasing the metallicity of the ejecta. High-metallicity
models fit well at early epochs, but not as well as solar-metallicity models
after maximum light. While this blend of metal lines is a reasonable
explanation of the source of the 6200 Angstrom feature, it is still important
to investigate hydrogen as the source; therefore, a second paper will present
models that include a thin shell of hydrogen around the main composition
structure.


title:
Muon spin relaxation and hyperfine-enhanced 141Pr nuclear spin dynamic
  in Pr(Os,Ru)4Sb12 and (Pr,La)Os4Sb12

abstract:
  Zero- and longitudinal-field muon spin relaxation (MuSR) experiments have
been carried out in the alloy series Pr(Os1-xRux)4Sb12 and Pr1-yLayOs4Sb12 to
elucidate the anomalous dynamic muon spin relaxation observed in these
materials. The damping rate associated with this relaxation varies with
temperature, applied magnetic field, and dopant concentrations x and y in a
manner consistent with the ``hyperfine enhancement'' of 141Pr nuclear spins
first discussed by Bleaney in 1973. This mechanism arises from Van Vleck-like
admixture of magnetic Pr3+ crystalline-electric-field-split excited states into
the nonmagnetic singlet ground state by the nuclear hyperfine coupling, thereby
increasing the strengths of spin-spin interactions between 141Pr and muon spins
and within the 141Pr spin system. We find qualitative agreement with this
scenario, and conclude that electronic spin fluctuations are not directly
involved in the dynamic muon spin relaxation.


title:
Dangling-bond spin relaxation and magnetic 1/f noise from the
  amorphous-semiconductor/oxide interface: Theory

abstract:
  We propose a model for magnetic noise based on spin-flips (not
electron-trapping) of paramagnetic dangling-bonds at the
amorphous-semiconductor/oxide interface. A wide distribution of spin-flip times
is derived from the single-phonon cross-relaxation mechanism for a
dangling-bond interacting with the tunneling two-level systems of the amorphous
interface. The temperature and frequency dependence is sensitive to three
energy scales: The dangling-bond spin Zeeman energy delta, as well as the
minimum (E_min) and maximum (E_max) values for the energy splittings of the
tunneling two-level systems. We compare and fit our model parameters to a
recent experiment probing spin coherence of antimony donors implanted in
nuclear-spin-free silicon [T. Schenkel {\it et al.}, Appl. Phys. Lett. 88,
112101 (2006)], and conclude that a dangling-bond area density of the order of
10^{14}cm^{-2} is consistent with the data. This enables the prediction of
single spin qubit coherence times as a function of the distance from the
interface and the dangling-bond area density in a real device structure. We
apply our theory to calculations of magnetic flux noise affecting SQUID devices
due to their Si/SiO_2 substrate. Our explicit estimates of flux noise in SQUIDs
lead to a noise spectral density of the order of 10^{-12}Phi_{0}^{2} {Hz}^{-1}
at f=1Hz. This value might explain the origin of flux noise in some SQUID
devices. Finally, we consider the suppression of these effects using surface
passivation with hydrogen, and the residual nuclear-spin noise resulting from a
perfect silicon-hydride surface.


title: Local purity distillation with bounded classical communication

abstract:
  Local pure states are an important resource for quantum computing. The
problem of distilling local pure states from mixed ones can be cast in an
information theoretic paradigm. The bipartite version of this problem where
local purity must be distilled from an arbitrary quantum state shared between
two parties, Alice and Bob, is closely related to the problem of separating
quantum and classical correlations in the state and in particular, to a measure
of classical correlations called the one-way distillable common randomness. In
Phys. Rev. A 71, 062303 (2005), the optimal rate of local purity distillation
is derived when many copies of a bipartite quantum state are shared between
Alice and Bob, and the parties are allowed unlimited use of a unidirectional
dephasing channel. In the present paper, we extend this result to the setting
in which the use of the channel is bounded. We demonstrate that in the case of
a classical-quantum system, the expression for the local purity distilled is
efficiently computable and provide examples with their tradeoff curves.


title:
Global magnetohydrodynamical models of turbulence in protoplanetary
  disks I. A cylindrical potential on a Cartesian grid and transport of solids

abstract:
  We present global 3D MHD simulations of disks of gas and solids, aiming at
developing models that can be used to study various scenarios of planet
formation and planet-disk interaction in turbulent accretion disks. A second
goal is to show that Cartesian codes are comparable to cylindrical and
spherical ones in handling the magnetohydrodynamics of the disk simulations, as
the disk-in-a-box models presented here develop and sustain MHD turbulence. We
investigate the dependence of the magnetorotational instability on disk scale
height, finding evidence that the turbulence generated by the magnetorotational
instability grows with thermal pressure. The turbulent stresses depend on the
thermal pressure obeying a power law of 0.24+/-0.03, compatible with the value
of 0.25 found in shearing box calculations. The ratio of stresses decreased
with increasing temperature. We also study the dynamics of boulders in the
hydromagnetic turbulence. The vertical turbulent diffusion of the embedded
boulders is comparable to the turbulent viscosity of the flow. Significant
overdensities arise in the solid component as boulders concentrate in high
pressure regions.


title:
High Energy Activity of the Super-Massive Black Hole at the Galactic
  Center

abstract:
  The centre of our galaxy hosts the nearest super-massive black hole to the
solar system, identified to the compact radio source Sgr A*. High energy
experiments have tried in the past to detect the X/gamma-ray emission expected
from the accretion of the surrounding material into this super-massive black
hole. Only recently however, thanks to the new generation of telescopes, it has
been possible to reveal high energy radiation associated with Sgr A* or its
close environment. I will review and discuss in particular the results on the
Sgr A* X-ray flares discovered with Chandra and XMM-Newton, on the central soft
gamma-ray source detected with INTEGRAL and on the galactic centre TeV emission
revealed by HESS.


title:
Evidence for the Evolution of Young Early-Type Galaxies in the
  GOODS/CDF-S Field

abstract:
  We have developed an efficient photometric technique for identifying young
early-type galaxy candidates using a combination of photometric redshifts,
spectral-type classification, and optical/near-infrared colors. Applying our
technique to the GOODS HST/ACS and VLT/ISAAC data we have selected a complete
and homogeneous sample of young elliptical candidates among early-type field
galaxies. The distribution of structural parameters for these candidates shows
that their selection, which is based on early spectral types, is fully
consistent with early morphological types. We investigate the evolution of
their luminosities and colors as a function of redshift and galaxy mass and
find evidence for an increasing starburst mass fraction in these young
early-type galaxy candidates at higher redshifts, which we interpret in terms
of massive field galaxies experiencing more massive/intense starbursts at
higher redshifts. Moreover, we find indications for a systematically larger
young elliptical fraction among sub-L*/2 early-type galaxies compared to their
brighter counterparts. The total fraction among the field early-type galaxies
increases with redshift, irrespective of galaxy luminosity. Our results are
most consistent with galaxy formation scenarios in which stars in massive
early-type field galaxies are assembled earlier than in their low-mass
counterparts.


title: GHaFaS: Galaxy Halpha Fabry-Perot Spectrometer for the WHT

abstract:
  A new scanning Fabry-Perot system will soon be available at the Nasmyth focus
of the 4,2m William Hershell Telescope (WHT). It has been designed by the
Laboratoire d'Astrophysique Experimentale (LAE) in Montreal and is being built
in collaboration with astronomers at the Instituto de Astrofisica de Canarias
(IAC). The instrument will see first light at the beginning of July 2007.


title: Efficiency and Nash Equilibria in a Scrip System for P2P Networks

abstract:
  A model of providing service in a P2P network is analyzed. It is shown that
by adding a scrip system, a mechanism that admits a reasonable Nash equilibrium
that reduces free riding can be obtained. The effect of varying the total
amount of money (scrip) in the system on efficiency (i.e., social welfare) is
analyzed, and it is shown that by maintaining the appropriate ratio between the
total amount of money and the number of agents, efficiency is maximized. The
work has implications for many online systems, not only P2P networks but also a
wide variety of online forums for which scrip systems are popular, but formal
analyses have been lacking.


title: The variable radio-to-X-ray spectrum of the magnetar XTE J1810-197

abstract:
  We have observed the 5.54s anomalous X-ray pulsar XTE J1810-197 at radio,
millimeter, and infrared (IR) wavelengths, with the aim of learning about its
broad-band spectrum. At the IRAM 30m telescope, we have detected the magnetar
at 88 and 144GHz, the highest radio-frequency emission ever seen from a pulsar.
At 88GHz we detected numerous individual pulses, with typical widths ~2ms and
peak flux densities up to 45Jy. Together with nearly contemporaneous
observations with the Parkes, Nancay, and Green Bank telescopes, we find that
in late 2006 July the spectral index of the pulsar was -0.5<alpha<0 over the
range 1.4-144GHz. Nine dual-frequency Very Large Array and Australia Telescope
Compact Array observations in 2006 May-September are consistent with this
finding, while showing variability of alpha with time. We infer from the IRAM
observations that XTE J1810-197 remains highly linearly polarized at millimeter
wavelengths. Also, toward this pulsar, the transition frequency between strong
and weak scattering in the interstellar medium may be near 50GHz. At Gemini, we
detected the pulsar at 2.2um in 2006 September, at the faintest level yet
observed, K_s=21.89+-0.15. We have also analyzed four archival IR Very Large
Telescope observations (two unpublished), finding that the brightness
fluctuated within a factor of 2-3 over a span of 3 years, unlike the monotonic
decay of the X-ray flux. Thus, there is no correlation between IR and X-ray
flux, and it remains uncertain whether there is any correlation between IR and
radio flux.


title: Diagrammatic approach to non-Gaussianity from inflation

abstract:
  We present Feynman type diagrams for calculating the n-point function of the
primordial curvature perturbation in terms of scalar field perturbations during
inflation. The diagrams can be used to evaluate the corresponding terms in the
n-point function at tree level or any required loop level. Rules are presented
for drawing the diagrams and writing down the corresponding terms in real space
and Fourier space. We show that vertices can be renormalised to automatically
account for diagrams with dressed vertices. We apply these rules to calculate
the primordial power spectrum up to two loops, the bispectrum including loop
corrections, and the trispectrum.


title: Probing the Geometry of Warped String Compactifications at the LHC

abstract:
  Warped string compactifications, characterized by non-singular behavior of
the metric in the infrared (IR), feature departures from the usual anti-de
Sitter warped extra dimensions. We study the implications of the smooth IR
cutoff for Randall-Sundrum (RS) type models. We find that the phenomenology of
the KK gravitons (including their masses and couplings) depends sensitively on
the precise shape of the warp factor in the IR. In particular, we analyze the
warped deformed conifold and find that the spectrum differs significantly from
that of RS, and present a simple prescription (a mass gap ansatz) which can be
used to study the phenomenology of IR modifications to 5-d warped extra
dimensions.


title:
Extended Holomorphic Anomaly and Loop Amplitudes in Open Topological
  String

abstract:
  Open topological string amplitudes on compact Calabi-Yau threefolds are shown
to satisfy an extension of the holomorphic anomaly equation of Bershadsky,
Cecotti, Ooguri and Vafa. The total topological charge of the D-brane
configuration must vanish in order to satisfy tadpole cancellation. The
boundary state of such D-branes is holomorphically captured by a Hodge
theoretic normal function. Its Griffiths' infinitesimal invariant is the
analogue of the closed string Yukawa coupling and plays the role of the
terminator in a Feynman diagram expansion for the topological string with
D-branes. The holomorphic anomaly equation is solved and the holomorphic
ambiguity is fixed for some representative worldsheets of low genus and with
few boundaries on the real quintic.


title: Theory of the nodal nematic quantum phase transition in superconductors

abstract:
  We study the character of an Ising nematic quantum phase transition (QPT)
deep inside a d-wave superconducting state with nodal quasiparticles in a
two-dimensional tetragonal crystal. We find that, within a 1/N expansion, the
transition is continuous. To leading order in 1/N, quantum fluctuations enhance
the dispersion anisotropy of the nodal excitations, and cause strong scattering
which critically broadens the quasiparticle (qp) peaks in the spectral
function, except in a narrow wedge in momentum space near the Fermi surface
where the qp's remain sharp. We also consider the possible existence of a
nematic glass phase in the presence of weak disorder. Some possible
implications for cuprate physics are also discussed.


title:
The inner jet of radio galaxy NGC 315 as observed with Chandra and the
  VLA

abstract:
  We present Chandra X-ray results for the jet, nucleus, and gaseous atmosphere
of NGC 315, a nearby radio galaxy whose jet kinematics are known through deep
radio mapping. Diffuse X-ray synchrotron emission is detected from the jet out
to 30 arcsec from the nucleus, through regions both of fast bulk flow and
deceleration. The X-ray to radio flux ratio drops considerably where the flow
decelerates, but the X-ray and radio emissions show similar transverse extents
throughout, requiring distributed particle acceleration to maintain the supply
of X-ray-emitting electrons. A remarkable knotty filament within the jet is
seen in both the radio and X-ray, contributing roughly 10 per cent of the
diffuse emission along its extent at both wavelengths. No completely
satisfactory explanation for the filament is found, though its oscillatory
appearance, roughly aligned magnetic field, and requirements for particle
acceleration, suggest that it is a magnetic strand within a shear layer between
fast inner and slower outer flow.


title: Properties of a Gamma Ray Burst Host Galaxy at z ~ 5

abstract:
  We describe the properties of the host galaxy of the gamma-ray burst
GRB060510B based on a spectrum of the burst afterglow obtained with the Gemini
North 8m telescope. The galaxy lies at a redshift of z = 4.941 making it the
fourth highest spectroscopically identified burst host. However, it is the
second highest redshift galaxy for which the quality of the spectrum permits a
detailed metallicity analysis. The neutral hydrogen column density has a
logarithmic value of 21.0--21.2 cm^-2 and the weak metal lines of Ni, S and Fe
show that the metallicity is in excess of a tenth of solar which is far above
the metallicities in damped Lyman alpha absorbers at high redshift. The
tightest constraint is from the Fe lines which place [Fe/H] in excess of -0.8.
We argue that the results suggest that metallicity bias could be a serious
problem with inferring star formation from the GRB population and consider how
future higher quality measurements could be used to resolve this question.


title: Resource Letter: Dark Energy and the Accelerating Universe

abstract:
  This Resource Letter provides a guide to the literature on dark energy and
the accelerating universe. It is intended to be of use to researchers,
teachers, and students at several levels. Journal articles, books, and websites
are cited for the following topics: Einstein's cosmological constant,
quintessence or dynamical scalar fields, modified cosmic gravity, relations to
high energy physics, cosmological probes and observations, terrestrial probes,
calculational tools and parameter estimation, teaching strategies and
educational resources, and the fate of the universe.


title:
Selection Bias in Observing the Cosmological Evolution of the Mbh-sigma
  and Mbh-L Relationships

abstract:
  Programs to observe evolution in the Mbh-sigma or Mbh-L relations typically
compare black-hole masses, Mbh, in high-redshift galaxies selected by nuclear
activity to Mbh in local galaxies selected by luminosity L, or stellar velocity
dispersion sigma. Because AGN luminosity is likely to depend on Mbh, selection
effects are different for high-redshift and local samples, potentially
producing a false signal of evolution. This bias arises because cosmic scatter
in the Mbh-sigma and Mbh-L relations means that the mean log(L) or log(sigma)
among galaxies that host a black hole of given Mbh, may be substantially
different than the log(L) or log(sigma) obtained from inverting the Mbh-L or
Mbh-sigma relations for the same nominal Mbh. The bias is particularly strong
at high Mbh, where the luminosity and dispersion functions of galaxies are
falling rapidly. The most massive black holes occur more often as rare outliers
in galaxies of modest mass than in the even rarer high-mass galaxies, which
would otherwise be the sole location of such black holes in the absence of
cosmic scatter. Because of this bias, Mbh will typically appear to be too large
in the distant sample for a given L or sigma. For the largest black holes and
the largest plausible cosmic scatter, the bias can reach a factor of 3 in Mbh
for the Mbh-sigma relation and a factor of 9 for the Mbh-L relation.
Unfortunately, the actual cosmic scatter is not known well enough to correct
for the bias. Measuring evolution of the Mbh and galaxy property relations
requires object selection to be precisely defined and exactly the same at all
redshifts.


title: On Newton's law in supersymmetric braneworld models

abstract:
  We study the propagation of gravitons within 5-D supersymmetric braneworld
models with a bulk scalar field. The setup considered here consists of a 5-D
bulk spacetime bounded by two 4-D branes localized at the fixed points of an
$S^1/Z_2$ orbifold. There is a scalar field $\phi$ in the bulk which, provided
a superpotential $W(\phi)$, determines the warped geometry of the 5-D
spacetime. This type of scenario is common in string theory, where the bulk
scalar field $\phi$ is related to the volume of small compact extra dimensions.
We show that, after the moduli are stabilized by supersymmetry breaking terms
localized on the branes, the only relevant degrees of freedom in the bulk
consist of a 5-D massive spectrum of gravitons. Then we analyze the
gravitational interaction between massive bodies localized at the positive
tension brane mediated by these bulk gravitons. It is shown that the Newtonian
potential describing this interaction picks up a non-trivial contribution at
short distances that depends on the shape of the superpotential $W(\phi)$. We
compute this contribution for dilatonic braneworld scenarios $W(\phi) =
e^{\alpha \phi}$ (where $\alpha$ is a constant) and discuss the particular case
of 5-D Heterotic M-theory: It is argued that a specific footprint at micron
scales could be observable in the near future.


title: Dirac fermions in a power-law-correlated random vector potential

abstract:
  We study localization properties of two-dimensional Dirac fermions subject to
a power-law-correlated random vector potential describing, e.g., the effect of
"ripples" in graphene. By using a variety of techniques (low-order perturbation
theory, self-consistent Born approximation, replicas, and supersymmetry) we
make a case for a possible complete localization of all the electronic states
and compute the density of states.


title: Exchange-induced frustration in Fe/NiO multilayers

abstract:
  Using spin-polarized low-energy electron microscopy to study magnetization in
epitaxial layered systems, we found that the area vs perimeter relationship of
magnetic domains in the top Fe layers of Fe/NiO/Fe(100) structures follows a
power-law distribution, with very small magnetic domain cutoff radius (about 40
nm) and domain wall thickness. This unusual magnetic microstructure can be
understood as resulting from the competition between antiferromagnetic and
ferromagnetic exchange interactions at the Fe/NiO interfaces, rather than from
mechanisms involving the anisotropy and dipolar forces that govern length
scales in conventional magnetic domain structures. Statistical analysis of our
measurements validates a micromagnetic model that accounts for this interfacial
exchange coupling.


title: Non-perturbative aspects of Yang-Mills theories

abstract:
  Some nonperturbative aspects of Euclidean Yang-Mills theories in four
dimensions, quantized in the Landau gauge, are analytically studied. In
particular, we investigate the dynamical mass generation for the gluons due to
the presence of dimension two condensates. This study is performed in the
framework of the local composite operator technique in the case of the
Yang-Mills action as well as in the case of the Gribov-Zwanziger action.
Further, an investigation of the Gribov ambiguities in the linear covariant
gauges is presented.


title: Astronomical bounds on future big freeze singularity

abstract:
  Recently it was found that dark energy in the form of phantom generalized
Chaplygin gas may lead to a new form of the cosmic doomsday, the big freeze
singularity. Like the big rip singularity, the big freeze singularity would
also take place at a finite future cosmic time, but unlike the big rip
singularity it happens for a finite scale factor.Our goal is to test if a
universe filled with phantom generalized Chaplygin gas can conform to the data
of astronomical observations. We shall see that if the universe is only filled
with generalized phantom Chaplygin gas with equation of state
$p=-c^2s^2/\rho^{\alpha}$ with $\alpha<-1$, then such a model cannot be matched
to the data of astronomical observations. To construct matched models one
actually need to add dark matter. This procedure results in cosmological
scenarios which do not contradict the data of astronomical observations and
allows one to estimate how long we are now from the future big freeze doomsday.


title: Dynamical models with a general anisotropy profile

abstract:
  Both numerical simulations and observational evidence indicate that the outer
regions of galaxies and dark matter haloes are typically mildly to
significantly radially anisotropic. The inner regions can be significantly
non-isotropic, depending on the dynamical formation and evolution processes. In
an attempt to break the lack of simple dynamical models that can reproduce this
behaviour, we explore a technique to construct dynamical models with an
arbitrary density and an arbitrary anisotropy profile. We outline a general
construction method and propose a more practical approach based on a
parameterized anisotropy profile. This approach consists of fitting the density
of the model with a set of dynamical components, each of which have the same
anisotropy profile. Using this approach we avoid the delicate fine-tuning
difficulties other fitting techniques typically encounter when constructing
radially anisotropic models. We present a model anisotropy profile that
generalizes the Osipkov-Merritt profile, and that can represent any smooth
monotonic anisotropy profile. Based on this model anisotropy profile, we
construct a very general seven-parameter set of dynamical components for which
the most important dynamical properties can be calculated analytically. We use
the results to look for simple one-component dynamical models that generate
simple potential-density pairs while still supporting a flexible anisotropy
profile. We present families of Plummer and Hernquist models in which the
anisotropy at small and large radii can be chosen as free parameters. We also
generalize these two families to a three-parameter family that
self-consistently generates the set of Veltmann potential-density pairs.
(Abridged...)


title: Optimizing Scrip Systems: Efficiency, Crashes, Hoarders, and Altruists

abstract:
  We discuss the design of efficient scrip systems and develop tools for
empirically analyzing them. For those interested in the empirical study of
scrip systems, we demonstrate how characteristics of agents in a system can be
inferred from the equilibrium distribution of money. From the perspective of a
system designer, we examine the effect of the money supply on social welfare
and show that social welfare is maximized by increasing the money supply up to
the point that the system experiences a ``monetary crash,'' where money is
sufficiently devalued that no agent is willing to perform a service. We also
examine the implications of the presence of altruists and hoarders on the
performance of the system. While a small number of altruists may improve social
welfare, too many can also cause the system to experience a monetary crash,
which may be bad for social welfare. Hoarders generally decrease social welfare
but, surprisingly, they also promote system stability by helping prevent
monetary crashes. In addition, we provide new technical tools for analyzing and
computing equilibria by showing that our model exhibits strategic
complementarities, which implies that there exist equilibria in pure strategies
that can be computed efficiently.


title:
Remarks on the existence of bilaterally symmetric extremal K\"ahler
  metrics on $\mathbb{CP}^2\sharp 2\bar{\mathbb{CP}^2}$

abstract:
  In this short note we show that the existence of bilaterally symmetric
extremal K\"ahler metrics on $\mathbb{CP}^2\sharp 2\bar{\mathbb{CP}^2}$.


title: Microscopic Origin of Non-Gaussian Distributions of Financial Returns

abstract:
  In this paper we study the possible microscopic origin of heavy-tailed
probability density distributions for the price variation of financial
instruments. We extend the standard log-normal process to include another
random component in the so-called stochastic volatility models. We study these
models under an assumption, akin to the Born-Oppenheimer approximation, in
which the volatility has already relaxed to its equilibrium distribution and
acts as a background to the evolution of the price process. In this
approximation, we show that all models of stochastic volatility should exhibit
a scaling relation in the time lag of zero-drift modified log-returns. We
verify that the Dow-Jones Industrial Average index indeed follows this scaling.
We then focus on two popular stochastic volatility models, the Heston and
Hull-White models. In particular, we show that in the Hull-White model the
resulting probability distribution of log-returns in this approximation
corresponds to the Tsallis (t-Student) distribution. The Tsallis parameters are
given in terms of the microscopic stochastic volatility model. Finally, we show
that the log-returns for 30 years Dow Jones index data is well fitted by a
Tsallis distribution, obtaining the relevant parameters.


title:
Strangers in the night: Discovery of a dwarf spheroidal galaxy on its
  first Local Group infall

abstract:
  We present spectroscopic observations of the AndXII dwarf spheroidal galaxy
using DEIMOS/Keck-II, showing it to be moving rapidly through the Local Group
(-556 km/s heliocentric velocity, -281 km/s relative to Andromeda from the MW),
falling into the Local Group from ~115 kpc beyond Andromeda's nucleus. AndXII
therefore represents a dwarf galaxy plausibly falling into the Local Group for
the first time, and never having experienced a dense galactic environment. From
Green Bank Telescope observations, a limit on the H{I} gas mass of <3000 Msun
suggests that AndXII's gas could have been removed prior to experiencing the
tides of the Local Group galaxies. Orbit models suggest the dwarf is close to
the escape velocity of M31 for published mass models. AndXII is our best direct
evidence for the late infall of satellite galaxies, a prediction of
cosmological simulations.


title:
Bethe algebra and algebra of functions on the space of differential
  operators of order two with polynomial solutions

abstract:
  We show that the following two algebras are isomorphic. The first is the
algebra $A_P$ of functions on the scheme of monic linear second-order
differential operators on $\C$ with prescribed regular singular points at
$z_1,..., z_n, \infty$, prescribed exponents $\La^{(1)}, ..., \La^{(n)},
\La^{(\infty)}$ at the singular points, and having the kernel consisting of
polynomials only. The second is the Bethe algebra of commuting linear
operators, acting on the vector space $\Sing L_{\La^{(1)}} \otimes ... \otimes
L_{\La^{(n)}}[\La^{(\infty)}]$ of singular vectors of weight $\La^{(\infty)}$
in the tensor product of finite dimensional polynomial $gl_2$-modules with
highest weights $\La^{(1)},..., \La^{(n)}$.


title: Linear meson and baryon trajectories in AdS/QCD

abstract:
  An approximate holographic dual of QCD is constructed and shown to reproduce
the empirical linear trajectories of universal slope on which the square masses
of radially and orbitally excited hadrons join. Conformal symmetry breaking and
other IR effects are described exclusively by deformations of the anti-de
Sitter background metric. The predictions for the light hadron spectrum include
new relations between ground state masses and trajectory slopes and are in good
overall agreement with experimental data.


title:
Almost sure functional central limit theorem for ballistic random walk
  in random environment

abstract:
  We consider a multidimensional random walk in a product random environment
with bounded steps, transience in some spatial direction, and high enough
moments on the regeneration time. We prove an invariance principle, or
functional central limit theorem, under almost every environment for the
diffusively scaled centered walk. The main point behind the invariance
principle is that the quenched mean of the walk behaves subdiffusively.


title: Like-sign dilepton signals from a leptophobic Z' boson

abstract:
  A new leptophobic neutral gauge boson Z' with small mixing to the Z can have
a mass as light as M_Z' ~ 350 GeV, and still have escaped detection at LEP and
Tevatron. Such a Z' boson can be derived from E6 and, if the new heavy neutrino
singlets in the 27 representation are lighter than M_Z'/2, the process p
p(pbar) -> Z' -> NN -> l+- l+- X is observable. Indeed, this new signal could
explain the small excess of like-sign dileptons found at Tevatron. Implications
for LHC are also discussed. In particular, the Tevatron excess could be
confirmed with less than 1 fb-1, and leptophobic Z' masses up to 2.5 TeV can be
probed with 30 fb-1.


title:
Magnetic fields above the surface of a superconductor with internal
  magnetism

abstract:
  The author presents a method for calculating the magnetic fields near a
planar surface of a superconductor with a given intrinsic magnetization in the
London limit. He computes solutions for various magnetic domain boundary
configurations and derives relations between the spectral densities of the
magnetization and the resulting field in the vacuum half space, which are
useful if the magnetization can be considered as a statistical quantity and its
features are too small to be resolved individually. The results are useful for
analyzing and designing magnetic scanning experiments. Application to existing
data from such experiments on Sr$_2$RuO$_4$ show that a domain wall would have
been detectable, but the magnetic field of randomly oriented small domains and
small defects may have been smaller than the experimental noise level.


title: Fidelity enhancement by logical qubit encoding

abstract:
  We demonstrate coherent control of two logical qubits encoded in a
decoherence free subspace (DFS) of four dipolar-coupled protons in an NMR
quantum information processor. A pseudo-pure fiducial state is created in the
DFS, and a unitary logical qubit entangling operator evolves the system to a
logical Bell state. The four-spin molecule is partially aligned by a liquid
crystal solvent, which introduces strong dipolar couplings among the spins.
Although the system Hamiltonian is never fully specified, we demonstrate high
fidelity control over the logical degrees of freedom. In fact, the DFS encoding
leads to higher fidelity control than is available in the full four-spin
Hilbert space.


title: Spacetime as a deformable solid

abstract:
  In this letter we discuss the possibility of treating the spacetime by itself
as a kind of deformable body for which we can define an fundamental lattice,
just like atoms in crystal lattices. We show three signs pointing in that
direction. We simulate the spacetime manifold by a very specific congruence of
curves and use the Landau-Raychadhuri equation to study the behavior of such a
congruence. The lattice appears because we are forced to associate to each
curve of the congruence a sort of fundamental "particle". The world-lines of
these particles should be identified with the congruence fulfilling the
spacetime manifold. The conclusion is that when describing the deformations of
the spacetime the Einstein equations emerge and the spacetime metric should be
treated as a secondary (not fundamental) object of the theory.


title:
Gravitational instability of a dilute fully ionized gas in the presence
  of the Dufour effect

abstract:
  The gravitational instability of a fully ionized gas is analyzed within the
framework of linear irreversible thermodynamics. In particular, the presence of
a heat flux corresponding to generalized thermodynamic forces is shown to
affect the properties of the dispersion relation governing the stability of
this kind of system in certain problems of interest.


title: Finding Minimal Permutation Representations of Finite Groups

abstract:
  A minimal permutation representation of a finite group G is a faithful G-set
with the smallest possible size. We study the structure of such representations
and show that for certain groups they may be obtained by a greedy construction.
In these situations (except when central involutions intervene) all minimal
permutation representations have the same set of orbit sizes. Using the same
ideas we also show that if the size d(G) of a minimal faithful G-set is at
least c|G| for some c>0 then d(G) = |G|/m + O(1) for an integer m, with the
implied constant depending on c.


title: The Call of Mathematics

abstract: A few remarks on how mathematics quests for freedom.


title: Interaction of Order and Convexity

abstract:
  This is an overview of merging the techniques of Riesz space theory and
convex geometry.