title: Gibbs-non-Gibbs properties for n-vector lattice and mean-field models

abstract:
  We review some recent developments in the study of Gibbs and non-Gibbs
properties of transformed n-vector lattice and mean-field models under various
transformations. Also, some new results for the loss and recovery of the Gibbs
property of planar rotor models during stochastic time evolution are presented.

categories: math-ph cond-mat.stat-mech math.MP math.PR


title: Palindromic random trigonometric polynomials

abstract:
  We show that if a real trigonometric polynomial has few real roots, then the
trigonometric polynomial obtained by writing the coefficients in reverse order
must have many real roots. This is used to show that a class of random
trigonometric polynomials has, on average, many real roots. In the case that
the coefficients of a real trigonometric polynomial are independently and
identically distributed, but with no other assumptions on the distribution, the
expected fraction of real zeros is at least one-half. This result is best
possible.


title: Lattice study of K pi scattering in I = 3/2 and 1/2

abstract:
  We report the first lattice QCD results of the scattering amplitudes of the
$K\pi$ system for $I = 1/2$ channel together with $I=3/2$ case. We investigate
all quark diagrams contributing to these iso-spin states, and find that the
scattering amplitudes are expressed as combinations of only three diagrams
after setting the masses of $u$-quark and $d$-quark to be the same.
  The lattice simulations are performed in the quenched approximation at $\beta
= 2.23$ on a 12$^3 \times 24$ lattice with an improved Iwasaki gauge action. We
employ a new dilution-type noise method to get accuracy of data with reasonable
CPU time. A simple method is proposed and applied to eliminate lattice artefact
due to the finite extent of lattice along the time direction.
  A clear difference in the quark mass dependence between $I=3/2$ and $I=1/2$
channels is observed. Although the chiral extrapolation is subtle, we assume
$E_{K\pi}^2 \propto m_{u,d}^2 $, and obtain the $S$-wave scattering lengths as
$a_0(I=3/2) m_{\pi} =-0.084^{+0.051}_{-0.064}$ and $a_0(I=1/2) m_{\pi} = -0.625
\pm0.012$. We show all necessary formulas which make the calculation possible.
  We argue that $\Lambda N$ is the most appropriate target of the L\"uscher's
formula for baryonic system because it has no $\pi$ exchange diagrams and has a
scattering length suitable for a lattice QCD simulation.


title: Dark energy of the Universe as a field of particles with spin 3

abstract:
  A hypothesis is presented for explanation of the dark matter and dark energy
properties in terms of a new interaction field with spin 3.


title:
Local Star formation triggered by SN shocks in magnetized diffuse
  neutral clouds

abstract:
  In this work, considering the impact of a SNR with a neutral magnetized cloud
we derived analytically a set of conditions which are favorable for driving
gravitational instability in the cloud and thus star formation. We have built
diagrams of the SNR radius, versus the cloud density, that constrain a domain
in the parameter space where star formation is allowed. The diagrams are also
tested with fully 3-D MHD simulations involving a SNR and a self-gravitating
cloud and we find that the numerical analysis is consistent with the results
predicted by the diagrams. While the inclusion of a homogeneous magnetic field
approximately perpendicular to the impact velocity of the SNR with an intensity
~1 $ mu$G results only a small shrinking of the star formation triggering zone
in the diagrams, a larger magnetic field (~10 $ mu$G) causes a significant
shrinking, as expected. Applications of the diagrams to a few regions of our
own galaxy have revealed that star formation in those sites could have been
triggered by shock waves from SNRs. Finally, we have evaluated the effective
star formation efficiency for this sort of interaction and found that it is
smaller than the observed values in our own Galaxy (sfe ~0.01-0.3). This result
is consistent with previous work in the literature and also suggests that the
mechanism presently investigated, though very powerful to drive structure
formation, supersonic turbulence and eventually, local star formation, does not
seem to be sufficient to drive global star formation in normal star forming
galaxies, not even when the magnetic field in the neutral clouds is neglected.
(abridged)


title:
Analysis of non-Gaussian CMB maps based on the N-pdf. Application to
  WMAP data

abstract:
  We present a new method based on the N-point probability distribution (pdf)
to study non-Gaussianity in cosmic microwave background (CMB) maps. Likelihood
and Bayesian estimation are applied to a local non-linear perturbed model up to
third order, characterized by a linear term which is described by a Gaussian
N-pdf, and a second and third order terms which are proportional to the square
and the cube of the linear one. We also explore a set of model selection
techniques (the Akaike and the Bayesian Information Criteria, the minimum
description length, the Bayesian Evidence and the Generalized Likelihood Ratio
Test) and their application to decide whether a given data set is better
described by the proposed local non-Gaussian model, rather than by the standard
Gaussian temperature distribution. As an application, we consider the analysis
of the WMAP 5-year data at a resolution of around 2 degrees. At this angular
scale (the Sachs-Wolfe regime), the non-Gaussian description proposed in this
work defaults (under certain conditions) to an approximative local form of the
weak non-linear coupling inflationary model (e.g. Komatsu & Spergel 2001)
previously addressed in the literature. For this particular case, we obtain an
estimation for the non-linear coupling parameter of -94 < F_nl < 154 at 95% CL.
Equally, model selection criteria also indicate that the Gaussian hypothesis is
favored against the particular local non-Gaussian model proposed in this work.
This result is in agreement with previous findings obtained for equivalent
non-Gaussian models and with different non-Gaussian estimators. However, our
estimator based on the N-pdf is more efficient than previous estimators and,
therefore, provides tighter constraints on the coupling parameter at degree
angular resolution.


title: Michael Pupin Idvorsky and father Vasa Zivkovic

abstract:
  There is often a bond between two great men of a society at the time when one
is at the peak of his life and the other at its beginning. The great Serbian
19th century poet, clergyman and educator father Vasa Zivkovic, interceding in
favour of his student Mihajlo Pupin, significantly influenced the conditions
necessary for Pupin`s development into the person he later became. Mihajlo
Pupin was certainly not the only student to benefit from father Vasa Zivkovic
advice and material support. However their relationship is a perfect example of
an acclaimed person successfully influencing a person yet to win acclaim.


title:
Contribution to the asymptotic analysis of the Landau-de Gennes
  functional

abstract:
  In this paper we are interested in the Landau-de Gennes functional introduced
to study the transition between the smectic and nematic phases of a liquid
crystal. We define a reduced functional by constraining the director field to
satisfy a non-homogeneous Dirichlet condition and we prove that, below a
critical temperature and if some elastic coefficients are explicitly large,
then, the minimizers have to be nematic phases.


title:
Hawking Radiation via Gravitational Anomalies in Non-spherical
  Topologies

abstract:
  We study the method of calculating the Hawking radiation via gravitational
anomalies in gravitational backgrounds of constant negative curvature. We apply
the method to topological black holes and also to topological black holes
conformally coupled to a scalar field.


title: Efficiency of structured adiabatic quantum computation

abstract:
  We show enough evidence that a structured version of Adiabatic Quantum
Computation (AQC) is efficient for most satisfiability problems. More
precisely, when the success probability is fixed beforehand, the computational
resources grow subexponentially in the number of qubits. Our study focuses on
random satisfiability and exact cover problems, developing a multi-step
algorithm that solves clauses one by one. Relating the computational cost to
classical properties of the problem, we collect significant statistics with up
to N=140 qubits, around the phase transitions, which is where the hardest
problems appear.


title: Optimal Matrix Product States for the Heisenberg Spin Chain

abstract:
  We present some exact results for the optimal Matrix Product State (MPS)
approximation to the ground state of the infinite isotropic Heisenberg spin-1/2
chain. Our approach is based on the systematic use of Schmidt decompositions to
reduce the problem of approximating for the ground state of a spin chain to an
analytical minimization. This allows to show that results of standard
simulations, e.g. density matrix renormalization group and infinite time
evolving block decimation, do correspond to the result obtained by this
minimization strategy and, thus, both methods deliver optimal MPS with the same
energy but, otherwise, different properties. We also find that translational
and rotational symmetries cannot be maintained simultaneously by the MPS ansatz
of minimum energy and present explicit constructions for each case.
Furthermore, we analyze symmetry restoration and quantify it to uncover new
scaling relations. The method we propose can be extended to any translational
invariant Hamiltonian.


title: On the stability of self-gravitating accreting flows

abstract:
  Analytic methods show stability of the stationary accretion of test fluids
but they are inconclusive in the case of self-gravitating stationary flows. We
investigate numerically stability of those stationary flows onto compact
objects that are transonic and rich in gas. In all studied examples solutions
appear stable. Numerical investigation suggests also that the analogy between
sonic and event horizons holds for small perturbations of compact support but
fails in the case of finite perturbations.


title: The symbiosis of C*- and W*-algebras

abstract:
  These days it is common for young operator algebraists to know a lot about
C*-algebras, or a lot about von Neumann algebras -- but not both. Though a
natural consequence of the breadth and depth of each subject, this is
unfortunate as the interplay between the two theories has deep historical roots
and has led to many beautiful results. We review some of these connections, in
the context of amenability, with the hope of convincing (younger) readers that
tribalism impedes progress.


title: Mott transition and integrable lattice models in two dimensions

abstract:
  We describe the two-dimensional Mott transition in a Hubbard-like model with
nearest neighbors interactions based on a recent solution to the Zamolodchikov
tetrahedron equation, which extends the notion of integrability to
two-dimensional lattice systems. At the Mott transition, we find that the
system is in a d-density wave or staggered flux phase that can be described by
a double Chern Simons effective theory with symmetry \su2 \otimes \su2. The
Mott transition is of topological nature, characterized by the emergence of
vortices in antiferromagnetic arrays interacting strongly with the electric
charges and an electric-magnetic duality. We also consider the effect of small
doping on this theory and show that it leads to a quantum gas-liquid
coexistence phase, which belongs to the Ising universality class and which is
consistent with several experimental observations.


title: Infinite volume limit for the dipole gas

abstract:
  We consider a classical dipole gas in with low activity and show that the
pressure has a limit as the volume goes to infinity. The result is obtained by
a renormalization group analysis of the model.


title: On harmonic binomial series

abstract:
  We evaluate binomial series with harmonic number coefficients, providing
recursion relations, integral representations, and several examples. The
results are of interest to analytic number theory, the analysis of algorithms,
and calculations of theoretical physics, as well as other applications.


title:
Negative modes and the thermodynamics of Reissner-Nordstr\"om black
  holes

abstract:
  We analyse the problem of negative modes of the Euclidean section of the
Reissner-Nordstr\"om black hole in four dimensions. We find analytically that a
negative mode disappears when the specific heat at constant charge becomes
positive. The sector of perturbations analysed here is included in the
canonical partition function of the magnetically charged black hole. The result
obeys the usual rule that the partition function is only well-defined when
there is local thermodynamical equilibrium. We point out the difficulty in
quantising Einstein-Maxwell theory, where the so-called conformal factor
problem is considerably more intricate. Our method, inspired by hep-th/0608001,
allows us to decouple the divergent gauge volume and treat the metric
perturbations sector in a gauge-invariant way.


title: The escaping set of the exponential

abstract:
  We show that the points that converge to infinity under iteration of the
exponential map form a connected subset of the complex plane.


title:
Pumping of vibrational excitations in a Coulomb blockaded suspended
  carbon nanotube

abstract:
  Low-temperature transport spectroscopy measurements on a suspended few-hole
carbon nanotube quantum dot are presented, showing a gate-dependent harmonic
excitation spectrum which, strikingly, occurs in the Coulomb blockade regime.
The quantized excitation energy corresponds to the scale expected for
longitudinal vibrations of the nanotube. The electronic transport processes are
identified as cotunnel-assisted sequential tunneling, resulting from
non-equilibrium occupation of the mechanical mode. They appear only above a
high-bias threshold at the scale of electronic nanotube excitations. We discuss
models for the pumping process that explain the enhancement of the
non-equilibrium occupation and show that it is connected to a subtle interplay
between electronic and vibrational degrees of freedom.


title: Laplacian Dynamics and Multiscale Modular Structure in Networks

abstract:
  Most methods proposed to uncover communities in complex networks rely on
their structural properties. Here we introduce the stability of a network
partition, a measure of its quality defined in terms of the statistical
properties of a dynamical process taking place on the graph. The time-scale of
the process acts as an intrinsic parameter that uncovers community structures
at different resolutions. The stability extends and unifies standard notions
for community detection: modularity and spectral partitioning can be seen as
limiting cases of our dynamic measure. Similarly, recently proposed
multi-resolution methods correspond to linearisations of the stability at short
times. The connection between community detection and Laplacian dynamics
enables us to establish dynamically motivated stability measures linked to
distinct null models. We apply our method to find multi-scale partitions for
different networks and show that the stability can be computed efficiently for
large networks with extended versions of current algorithms.


title: Eigenvalues from power--series expansions: an alternative approach

abstract:
  An appropriate rational approximation to the eigenfunction of the
Schr\"{o}dinger equation for anharmonic oscillators enables one to obtain the
eigenvalue accurately as the limit of a sequence of roots of Hankel
determinants. The convergence rate of this approach is greater than that for a
well--established method based on a power--series expansions weighted by a
Gaussian factor with an adjustable parameter (the so--called Hill--determinant
method).


title:
Membrane Dynamics in Three dimensional N=6 Supersymmetric Chern-Simons
  Theory

abstract:
  We study the membrane scattering in the three-dimensional N=6 supersymmetric
Chern-Simons theory recently constructed by Aharony, Bergman, Jafferis and
Maldacena and conjectured to be dual to M-theory on $AdS_4 \times S^7/Z_k$. We
compute the one-loop effective action up to the $v^4$ terms in the derivative
expansion and find exact agreement with the results from the supergravity
computations. In particular, our results imply that the $v^2$ term is not
renormalized and tree-level exact.


title: Remarks on the entanglement entropy for disconnected regions

abstract:
  Few facts are known about the entanglement entropy for disconnected regions
in quantum field theory. We study here the property of extensivity of the
mutual information, which holds for free massless fermions in two dimensions.
We uncover the structure of the entropy function in the extensive case, and
find an interesting connection with the renormalization group irreversibility.
The solution is a function on space-time regions which complies with all the
known requirements a relativistic entropy function has to satisfy. We show that
the holographic ansatz of Ryu and Takayanagi, the free scalar and Dirac fields
in dimensions greater than two, and the massive free fields in two dimensions
all fail to be exactly extensive, disproving recent conjectures.


title: UBVI CCD Photometry of the Old Open Cluster NGC 1193

abstract:
  We present UBVI photometry of the old open cluster NGC 1193. Color-magnitude
diagrams (CMDs) of this cluster show a well defined main sequence and a sparse
red giant branch. For the inner region of r<50 arcsec, three blue straggler
candidates are newly found in addition to the objects Kaluzny (1988) already
found. The color-color diagrams show that the reddening value toward NGC 1193
is E(B-V) =0.19 +/- 0.04. From the ultraviolet excess measurement, we derived
the metallicity to be [Fe/H]=-0.45 +/- 0.12. A distance modulus of (m-M)_0
=13.3 +/- 0.15 is obtained from zero age main sequence fitting with the
empirically calibrated Hyades isochrone of Pinsonneault et al. (2004). CMD
comparison with the Padova isochrones by Bertelli et al. (1994) gives an age of
log t =9.7 +/- 0.1.


title: Occupation times via Bessel functions

abstract:
  This study of occupation time densities for continuous-time Markov processes
was inspired by the work of E.Nir et al (2006) in the field of Single Molecule
FRET spectroscopy. There, a single molecule fluctuates between two or more
states, and the experimental observable depends on the state's occupation time
distribution. To mathematically describe the observable there was a need to
calculate a single state occupation time distribution.
  In this paper, we consider a Markov process with countably many states. In
order to find a one-stete occupation time density, we use a combination of
Fourier and Laplace transforms in the way that allows for inversion of the
Fourier transform. We derive an explicit expression for an occupation time
density in the case of a simple continuous time random walk on Z. Also we
examine the spectral measures in Karlin-McGregor diagonalization in an attempt
to represent occupation time densities via modified Bessel functions.


title: A Modified Coefficient Ideal for Use with the Strict Transform

abstract:
  Two main algorithmic approaches are known for making Hironaka's proof of
resolution of singularities in characteristic zero constructive. Their main
difference is the use of different notions of transforms during the resolution
process and the use of a stratification by the Hilbert-Samuel function in the
one using the strict transform. In this article, a (hybrid-type) algorithmic
approach is proposed which allows the use of the strict transform without the
full impact of the complexity of the stratification by the Hilbert-Samuel
function at each step of the desingularization process. This new approach is
not intended to always be superior to the implemented one which uses the weak
transform, instead it has its strengths precisely at the weak point of the
other one and is thus a candidate to be joined with it by an appropriate
heuristic.


title:
Equilibrium properties of simple metal thin films in the self-compressed
  stabilized jellium model

abstract:
  In this work, we have applied the self-compressed stabilized jellium model to
predict the equilibrium properties of isolated thin Al, Na, and Cs slabs. To
make a direct correspondence to atomic slabs, we have considered only those $L$
values that correspond to $n$-layered atomic slabs with $2\le n\le 20$, for
surface indices (100), (110), and (111). The calculations are based on the
density functional theory and self-consistent solution of the Kohn-Sham
equations in the local density approximation. Our results show that firstly,
the quantum size effects are significant for slabs with sizes smaller or near
to the Fermi wavelength of the valence electrons $\lambda_{\rm F}$, and
secondly, some slabs expand while others contract with respect to the bulk
spacings. Based on the results, we propose a criterion for realization of
significant quantum size effects that lead to expansion of some thin slabs. For
more justification of the criterion, we have tested on Li slabs for $2\le n\le
6$. We have compared our Al results with those obtained from using all-electron
or pseudo-potential first principles calculations. This comparison shows
excellent agreements for Al(100) work functions, and qualitatively good
agreements for the other work functions and surface energies. These agreements
justify the way we have used the self-compressed stabilized jellium model for
the correct description of the properties of the simple-metal slab systems. On
the other hand, our results for the work functions and surface energies of
large-$n$ slabs are in good agreement with those obtained from applying the
stabilized jellium model for semi-infinite systems. Moreover, we have performed
the slab calculations in the presence of surface corrugation for a selected Al
slabs and have shown that the results are worsened.


title:
The Impact of QoS Constraints on the Energy Efficiency of Fixed-Rate
  Wireless Transmissions

abstract:
  Transmission over wireless fading channels under quality of service (QoS)
constraints is studied when only the receiver has channel side information.
Being unaware of the channel conditions, transmitter is assumed to send the
information at a fixed rate. Under these assumptions, a two-state (ON-OFF)
transmission model is adopted, where information is transmitted reliably at a
fixed rate in the ON state while no reliable transmission occurs in the OFF
state. QoS limitations are imposed as constraints on buffer violation
probabilities, and effective capacity formulation is used to identify the
maximum throughput that a wireless channel can sustain while satisfying
statistical QoS constraints. Energy efficiency is investigated by obtaining the
bit energy required at zero spectral efficiency and the wideband slope in both
wideband and low-power regimes assuming that the receiver has perfect channel
side information (CSI). In both wideband and low-power regimes, the increased
energy requirements due to the presence of QoS constraints are quantified.
Comparisons with variable-rate/fixed-power and variable-rate/variable-power
cases are given. Energy efficiency is further analyzed in the presence of
channel uncertainties. The optimal fraction of power allocated to training is
identified under QoS constraints. It is proven that the minimum bit energy in
the low-power regime is attained at a certain nonzero power level below which
bit energy increases without bound with vanishing power.


title: Orthogonality and probability: beyond nearest neighbor transitions

abstract:
  In this article, we will explore why Karlin-McGregor method of using
orthogonal polynomials in the study of Markov processes was so successful for
one dimensional nearest neighbor processes, but failed beyond nearest neighbor
transitions. We will proceed by suggesting and testing possible fixtures.


title: On the Energy Efficiency of Orthogonal Signaling

abstract:
  In this paper, transmission over the additive white Gaussian noise (AWGN)
channel, and coherent and noncoherent fading channels using M-ary orthogonal
frequency-shift keying (FSK) or on-off frequency-shift keying (OOFSK) is
considered. The receiver is assumed to perform hard-decision detection. In this
setting, energy required to reliably send one bit of information is
investigated. It is shown that for fixed M and duty cycle, bit energy
requirements grow without bound as the signal-to-noise ratio (SNR) vanishes.
The minimum bit energy values are numerically obtained for different values of
M and the duty cycle. The impact of fading on the energy efficiency is
identified. Requirements to approach the minimum bit energy of -1.59 dB are
determined.


title: Primordial Magnetic Fields in Cosmology

abstract:
  Magnetic fields have been observed in galaxies, clusters of galaxies and
probably in superclusters. While mechanisms exist to generate these in the late
universe, it is possible that magnetic fields have existed since very early
times. This thesis is concerned with methods to predict the form of such
imprints. We review in detail a standard, linearised cosmology before
introducing an electromagnetic field. We then consider the intrinsic statistics
of the magnetic stresses in two ways, analytically and via static realisations.
We construct the power spectra, some of which we present for the first time. At
the one- and three-point level we find significant intrinsic non-Gaussianities.
Finally we turn to the observable impacts a primordial magnetic field. Assuming
coherence, the statistics of the source can be mapped onto the CMB in a simple
manner. We demonstrate that our approach is valid by reproducing the signals
for Gaussian power law fields on the microwave sky. [ABRIDGED]


title:
Relativistic BCS-BEC crossover of a two-species Fermi gas with number
  density asymmetry at zero temperature

abstract:
  We systematically study relativistic two-species fermions with tunable
attractive interactions and number-density asymmetry at zero temperature. In
general, a Bardeen-Cooper-Schrieffer (BCS) - Bose-Einstein Condensation (BEC) -
relativistic BEC (RBEC) crossover is observed. A generalized BCS ground state
and its stability are analyzed. The homogeneous superfluid phase can become
unstable and we consider phase separation in real space for neutral systems. In
the nonrelativistic limit, our results are consistent with well-known results.
In addition to a BCS-BEC crossover similar to that in the nonrelativistic case,
in the strongly attractive regime gapless excitations of antifermions and a
RBEC state are observed. We address how different phases respond to number
density asymmetry and present predictive phase diagrams of BCS-BEC-RBEC
crossover.


title: Two-generator subgroups of the pure braid group

abstract:
  We show that any two elements of the pure braid group either commute or
generate a free group, settling a question of Luis Paris. Our proof involves
the theory of 3-manifolds and the theory of group actions on trees.


title: Squeezed correlations among particle-antiparticle pairs

abstract:
  The hadronic correlation among particle-antiparticle pairs was highlighted in
the late 1990's, culminating with the demonstration that it should exist if the
masses of the hadrons were modified in the hot and dense medium formed in high
energy heavy ion collisions. They were called Back-to-Back Correlations (BBC)
of particle-antiparticle pairs, also known as squeezed correlations. However,
even though they are well-established theoretically, such hadronic correlations
have not yet been experimentally discovered. Expecting to compel the
experimentalists to search for this effect, we suggest here a clear way to look
for the BBC signal, by constructing the squeezed correlation function of
phi-phi and K+K- pairs at RHIC energies, plotted in terms of the average
momentum of the pair, K12=(k1+k2)/2, inspired by procedures adopted in
Hanbury-Brown & Twiss (HBT) correlations.


title: Kinetics of proton pumping in cytochrome c oxidase

abstract:
  We propose a simple model of cytochrome c oxidase, including four redox
centers and four protonable sites, to study the time evolution of
electrostatically coupled electron and proton transfers initiated by the
injection of a single electron into the enzyme. We derive a system of master
equations for electron and proton state probabilities and show that an
efficient pumping of protons across the membrane can be obtained for a
reasonable set of parameters. All four experimentally observed kinetic phases
appear naturally from our model. We also calculate the dependence of the
pumping efficiency on the transmembrane voltage at different temperatures and
discuss a possible mechanism of the redox-driven proton translocation.


title: Partial Reset in Pulse-Coupled Oscillators

abstract:
  Pulse-coupled threshold units serve as paradigmatic models for a wide range
of complex systems. When the state variable of a unit crosses a threshold, the
unit sends a pulse that is received by other units, thereby mediating the
interactions. At the same time, the state variable of the sending unit is
reset. Here we study pulse-coupled models with a reset that may be partial only
and is mediated by a partial reset function. Such a partial reset characterizes
intrinsic physical or biophysical features of a unit (e.g., resistive coupling
between dendrite and soma of compartmental neurons) and at the same time makes
possible a rigorous mathematical investigation of the collective network
dynamics.
  The partial reset acts as a desynchronization mechanism. For all-to-all
pulse-coupled oscillators an increase in the strength of the partial reset
causes a sequence of desynchronizing bifurcations from the fully synchronous
state via states with large clusters of synchronized units through states with
smaller clusters to complete asynchrony. We analytically derive sufficient and
necessary conditions for the existence and stability of periodic cluster states
on the local dynamics of the oscillators and on the partial reset function to
reveal the mechanism underlying the desynchronization transition. We show that
the entire sequence may occur due to arbitrarily small changes of the partial
reset and is robust against structural perturbations.


title: Neutrino induced pion production at MiniBooNE and K2K

abstract:
  We investigate charged and neutral current neutrino induced incoherent pion
production off nuclei at MiniBooNE and K2K energies within the GiBUU model. We
assume impulse approximation and treat the nucleus as a local Fermi gas of
nucleons bound in a mean-field potential. In-medium spectral functions are also
taken into account. The outcome of the initial neutrino nucleon reaction
undergoes complex hadronic final state interactions. We present results for
neutral current pi^0 and charged current pi^+ production and compare to
MiniBooNE and K2K data.


title:
Dynamical Electroweak Symmetry Breaking at the LHC on Supercomputers and
  in the Sky (Asymmetric Dark Matter)

abstract:
  I briefly review the basic challenges and virtues of models breaking the
electroweak symmetry dynamically. I will then introduce the (ultra) minimal
walking technicolor models whose construction has been made possible thanks to
recent progress in the understanding of the phase diagram for strongly coupled
theories as function of number of flavors, colors and matter representation. I
will mention possible relevant collider signatures. Interestingly, asymmetric
Dark Matter is a natural possibility in our models providing interesting
candidates for decaying Dark Matter models which have been explored to account
for the PAMELA and ATIC excesses in electron/positron cosmic rays.


title:
Discovery of Large-Scale Gravitational Infall in a Massive Protostellar
  Cluster

abstract:
  We report Mopra (ATNF), Anglo-Australian Telescope, and Atacama Submillimeter
Telescope Experiment observations of a molecular clump in Carina, BYF73 =
G286.21+0.17, which give evidence of large-scale gravitational infall in the
dense gas. From the millimetre and far-infrared data, the clump has mass ~ 2 x
10^4 Msun, luminosity ~ 2-3 x 10^4 Lsun, and diameter ~ 0.9 pc. From radiative
transfer modelling, we derive a mass infall rate ~ 3.4 x 10^-2 Msun yr-1. If
confirmed, this rate for gravitational infall in a molecular core or clump may
be the highest yet seen. The near-infrared K-band imaging shows an adjacent
compact HII region and IR cluster surrounded by a shell-like photodissociation
region showing H2 emission. At the molecular infall peak, the K imaging also
reveals a deeply embedded group of stars with associated H2 emission. The
combination of these features is very unusual and we suggest they indicate the
ongoing formation of a massive star cluster. We discuss the implications of
these data for competing theories of massive star formation.


title: M-brane singularity formation

abstract:
  We derive self-similar string solutions in a graph representation, near the
point of singularity formation, which can be shown to extend to point-like
singularities on M-branes, as well as to the radially symmetric case.


title:
The Nonisothermal Stage of Magnetic Star Formation. I. Formulation of
  the Problem and Method of Solution

abstract:
  We formulate the problem of the formation and subsequent evolution of
fragments (or cores) in magnetically-supported, self-gravitating molecular
clouds in two spatial dimensions. The six-fluid (neutrals, electrons, molecular
and atomic ions, positively-charged, negatively-charged, and neutral grains)
physical system is governed by the radiative, nonideal magnetohydrodynamic
(RMHD) equations. The magnetic flux is not assumed to be frozen in any of the
charged species. Its evolution is determined by a newly-derived generalized
Ohm's law, which accounts for the contributions of both elastic and inelastic
collisions to ambipolar diffusion and Ohmic dissipation. The species abundances
are calculated using an extensive chemical-equilibrium network. Both MRN and
uniform grain size distributions are considered. The thermal evolution of the
protostellar core and its effect on the dynamics are followed by employing the
grey flux-limited diffusion approximation. Realistic temperature-dependent
grain opacities are used that account for a variety of grain compositions. We
have augmented the publicly-available Zeus-MP code to take into consideration
all these effects and have modified several of its algorithms to improve
convergence, accuracy and efficiency. Results of magnetic star formation
simulations that accurately track the evolution of a protostellar fragment from
a density ~10^3 cm^-3 to a density ~10^15 cm^-3, while rigorously accounting
for both nonideal MHD processes and radiative transfer, are presented in a
separate paper.


title: Alpha effect and turbulent diffusion from convection

abstract:
  (abridged) Aims: To study turbulent transport coefficients that describe the
evolution of large-scale magnetic fields in turbulent convection. Methods: We
use the test field method together with 3D numerical simulations of turbulent
convection with shear and rotation to compute turbulent transport coefficients
describing the evolution of large-scale magnetic fields in mean-field theory in
the kinematic regime. 1D mean-field models are used with the derived turbulent
transport coefficients to compare with direct simulations. Results: The
alpha-effect increases monotonically as rotation increases. Turbulent
diffusivity, eta_t, is proportional to the square of the turbulent vertical
velocity. Whereas eta_t decreases approximately inversely proportional to the
wavenumber of the field, the alpha-effect and turbulent pumping show a more
complex behaviour. In the presence of shear and no rotation a small
alpha-effect is induced which does not seem to show any consistent trend as a
function of shear. If the shear is large enough, this small alpha is able to
excite a dynamo in the mean-field model. The coefficient responsible for
driving the shear-current effect shows several sign changes as a function of
depth but is also able to contribute to dynamo action in the mean-field model.
The growth rates in these cases are well below those in direct simulations
suggesting that an incoherent alpha-shear dynamo may also act in them. If both
rotation and shear are present, the alpha-effect is more pronounced. The
combination of the shear-current and Omega x J-effects is also stronger than in
the case of shear only, but subdominant to the alpha-shear dynamo. The results
of direct simulations are consistent with mean-field models where all of these
effects are taken into account without the need to invoke incoherent effects.


title:
Investigating superconductor-insulator transition in thin films using
  drag resistance:Theoretical analysis of a proposed experiment

abstract:
  The magnetically driven superconductor-insulator transition in amorphous thin
films (e.g., InO, Ta) exhibits several mysterious phenomena, such as a putative
metallic phase and a huge magnetoresistance peak. Unfortunately, several
conflicting categories of theories, particularly quantum-vortex condensation,
and normal region percolation, explain key observations equally well. We
propose a new experimental setup, an amorphous thin-film bilayer, where a drag
resistance measurement would clarify the role quantum vortices play in the
transition, and hence decisively point to the correct picture. We provide a
thorough analysis of the device, which shows that the vortex paradigm gives
rise to a drag with an opposite sign and orders of magnitude larger than the
drag measured if competing paradigms apply.


title: Being PC: Principal Components and Dark Energy

abstract:
  Principal component analysis is considered as an addition to the well-tested
parametrization w(a)=w_0+w_a(1-a) for the dark energy equation of state. This
brief note cautions against some unjustified assumptions in interpretation of
PCA calculations, giving quantified examples.


title: Theory of charged impurity scattering in two dimensional graphene

abstract:
  We review the physics of charged impurities in the vicinity of graphene. The
long-range nature of Coulomb impurities affects both the nature of the ground
state density profile as well as graphene's transport properties. We discuss
the screening of a single Coulomb impurity and the ensemble averaged density
profile of graphene in the presence of many randomly distributed impurities.
Finally, we discuss graphene's transport properties due to scattering off
charged impurities both at low and high carrier density.


title: Completeness of bond market driven by L\'evy process

abstract:
  The completeness problem of the bond market model with the random factors
determined by a Wiener process and Poisson random measure is studied. Hedging
portfolios use bonds with maturities in a countable, dense subset of a finite
time interval. It is shown that under natural assumptions the market is not
complete unless the support of the L\'evy measure consists of a finite number
of points. Explicit constructions of contingent claims which can not be
replicated are provided.


title: Tensors, non-Gaussianities, and the future of potential reconstruction

abstract:
  We present projections for reconstruction of the inflationary potential
expected from ESA's upcoming Planck Surveyor CMB mission. We focus on the
effects that tensor perturbations and the presence of non-Gaussianities have on
reconstruction efforts in the context of non-canonical inflation models. We
consider potential constraints for different combinations of
detection/null-detection of tensors and non-Gaussianities. We perform Markov
Chain Monte Carlo and flow analyses on a simulated Planck-precision data set to
obtain constraints. We find that a failure to detect non-Gaussianities
precludes a successful inversion of the primordial power spectrum, greatly
affecting uncertainties, even in the presence of a tensor detection. In the
absence of a tensor detection, while unable to determine the energy scale of
inflation, an observable level of non-Gaussianities provides correlations
between the errors of the potential parameters, suggesting that constraints
might be improved for suitable combinations of parameters. Constraints are
optimized for a positive detection of both tensors and non-Gaussianities.


title: h-> mu^+ mu^- via tth Production at the LHC

abstract:
  In this work, we examine the process at the LHC in which a Higgs boson is
produced in association with a t t-bar pair and subsequently decays to a pair
of muons. We show that the statistical significance for the discovery of a
light, Standard-Model Higgs boson with a mass around 120 GeV in this channel is
comparable to those for other processes (gluon fusion, weak-boson fusion) in
which the Higgs decays to a muon pair. Combining all three of these channels,
we show that evidence for a Higgs boson with a mass in the range 115 GeV < m_h
< 130 GeV could be obtained at the 3 sigma significance level with an
integrated luminosity of 300 fb^{-1}. We also calculate the enhancement factor
to the cross-section that would be needed to discover a non-standard Higgs
boson in this channel.


title: A cool starspot or a second transiting planet in the TrES-1 system?

abstract:
  We investigate the origin of a flux increase found during a transit of
TrES-1, observed with the HST. This feature in the HST light curve cannot be
attributed to noise and is supposedly a dark area on the stellar surface of the
host star eclipsed by TrES-1 during its transit. We investigate the likeliness
of two possible hypothesis for its origin: A starspot or a second transiting
planet. We made use of several transit observations of TrES-1 from space with
the HST and from ground with the IAC-80 telescope. On the basis of these
observations we did a statistical study of flux variations in each of the
observed events, to investigate if similar flux increases are present in other
parts of the data set. The HST observation presents a single clear flux rise
during a transit whereas the ground observations led to the detection of two
such events but with low significance. In the case of having observed a
starspot in the HST data, assuming a central impact between the spot and
TrES-1, we would obtain a lower limit for the spot radius of 42000 km. For this
radius the spot temperature would be 4690 K, 560 K lower then the stellar
surface of 5250 K. For a putative second transiting planet we can set a lower
limit for its radius at 0.37 R$_J$ and for periods of less than 10.5 days, we
can set an upper limit at 0.72 R$_J$. Assuming a conventional interpretation,
then this HST observation constitutes the detection of a starspot.
Alternatively, this flux rise might also be caused by an additional transiting
planet. The true nature of the origin can be revealed if a wavelength
dependency of the flux rise can be shown or discarded with a higher certainty.
Additionally, the presence of a second planet can also be detected by radial
velocity measurements.


title: The Local Dimension: a method to quantify the Cosmic Web

abstract:
  It is now well accepted that the galaxies are distributed in filaments,
sheets and clusters all of which form an interconnected network known as the
Cosmic Web. It is a big challenge to quantify the shapes of the interconnected
structural elements that form this network. Tools like the Minkowski
functionals which use global properties, though well suited for an isolated
object like a single sheet or filament, are not suited for an interconnected
network of such objects. We consider the Local Dimension $D$, defined through
$N(R)=A R^D$, where $N(R)$ is the galaxy number count within a sphere of
comoving radius $R$ centered on a particular galaxy, as a tool to locally
quantify the shape in the neigbourhood of different galaxies along the Cosmic
Web. We expect $D \sim 1,2$ and 3 for a galaxy located in a filament, sheet and
cluster respectively. Using LCDM N-body simulations we find that it is possible
to determine $D$ through a power law fit to $N(R)$ across the length-scales 2
to $10 {\rm Mpc}$ for $\sim 33 %$ of the galaxies. We have visually identified
the filaments and sheets corresponding to many of the galaxies with $D \sim 1$
and 2 respectively. In several other situations the structure responsible for
the $D$ value could not be visually identified, either due to its being tenuous
or due to other dominating structures in the vicinity. We also show that the
global distribution of the $D$ values can be used to visualize and interpret
how the different structural elements are woven into the Cosmic Web.


title:
An implementation of radiative transfer in the cosmological simulation
  code GADGET

abstract:
  We present a novel numerical implementation of radiative transfer in the
cosmological smoothed particle hydrodynamics (SPH) simulation code {\small
GADGET}. It is based on a fast, robust and photon-conserving integration scheme
where the radiation transport problem is approximated in terms of moments of
the transfer equation and by using a variable Eddington tensor as a closure
relation, following the `OTVET'-suggestion of Gnedin & Abel. We derive a
suitable anisotropic diffusion operator for use in the SPH discretization of
the local photon transport, and we combine this with an implicit solver that
guarantees robustness and photon conservation. This entails a matrix inversion
problem of a huge, sparsely populated matrix that is distributed in memory in
our parallel code. We solve this task iteratively with a conjugate gradient
scheme. Finally, to model photon sink processes we consider ionisation and
recombination processes of hydrogen, which is represented with a chemical
network that is evolved with an implicit time integration scheme. We present
several tests of our implementation, including single and multiple sources in
static uniform density fields with and without temperature evolution, shadowing
by a dense clump, and multiple sources in a static cosmological density field.
All tests agree quite well with analytical computations or with predictions
from other radiative transfer codes, except for shadowing. However, unlike most
other radiative transfer codes presently in use for studying reionisation, our
new method can be used on-the-fly during dynamical cosmological simulation,
allowing simultaneous treatments of galaxy formation and the reionisation
process of the Universe.


title: Brownian motion on the Sierpinski carpet

abstract:
  We prove that, up to scalar multiples, there exists only one local regular
Dirichlet form on a generalized Sierpinski carpet that is invariant with
respect to the local symmetries of the carpet. Consequently for each such
fractal the law of Brownian motion is uniquely determined and the Laplacian is
well defined.


title: Lectures on Moduli Spaces of Elliptic Curves

abstract:
  These informal notes are an expanded version of lectures on the moduli space
of elliptic curves given at Zhejiang University in July, 2008. Their goal is to
introduce and motivate basic concepts and constructions (such as orbifolds and
stacks) important in the study of moduli spaces of curves and abelian varieties
through the example of elliptic curves. The reason for working with elliptic
curves is that most constructions are elementary and explicit in this case. All
four approaches to moduli spaces of curves -- complex analytic, topological,
algebro-geometric, and number theoretic -- are considered. Topics covered
reflect my own biases. Very little, if anything, in these notes is original,
except perhaps the selection of topics and the point of view.


title:
Approximate factor analysis model building via alternating I-divergence
  minimization

abstract:
  Given a positive definite covariance matrix $\widehat \Sigma$, we strive to
construct an optimal \emph{approximate} factor analysis model $HH^\top +D$,
with $H$ having a prescribed number of columns and $D>0$ diagonal. The
optimality criterion we minimize is the I-divergence between the corresponding
normal laws. Lifting the problem into a properly chosen larger space enables us
to derive an alternating minimization algorithm \`a la Csisz\'ar-Tusn\'ady for
the construction of the best approximation. The convergence properties of the
algorithm are studied, with special attention given to the case where $D$ is
singular.


title: Cascade unlooping of a low-pitch helical spring under tension

abstract:
  We study the force vs extension behaviour of a helical spring made of a thin
torsionally-stiff anisotropic elastic rod. Our focus is on springs of very low
helical pitch. For certain parameters of the problem such a spring is found not
to unwind when pulled but rather to form hockles that pop-out one by one and
lead to a highly non-monotonic force-extension curve. Between abrupt loop
pop-outs this curve is well described by the planar elastica whose relevant
solutions are classified. Our results may be relevant for tightly coiled
nanosprings in future micro- and nano(electro)mechanical devices.


title: Geodesic stability, Lyapunov exponents and quasinormal modes

abstract:
  Geodesic motion determines important features of spacetimes. Null unstable
geodesics are closely related to the appearance of compact objects to external
observers and have been associated with the characteristic modes of black
holes. By computing the Lyapunov exponent, which is the inverse of the
instability timescale associated with this geodesic motion, we show that, in
the eikonal limit, quasinormal modes of black holes in any dimensions are
determined by the parameters of the circular null geodesics. This result is
independent of the field equations and only assumes a stationary, spherically
symmetric and asymptotically flat line element, but it does not seem to be
easily extendable to anti-de Sitter spacetimes. We further show that (i) in
spacetime dimensions greater than four, equatorial circular timelike geodesics
in a Myers-Perry black hole background are unstable, and (ii) the instability
timescale of equatorial null geodesics in Myers-Perry spacetimes has a local
minimum for spacetimes of dimension d > 5.


title:
Three-dimensional Finite Difference-Time Domain Solution of Dirac
  Equation

abstract:
  The Dirac equation is solved using three-dimensional Finite Difference-Time
Domain (FDTD) method. $Zitterbewegung$ and the dynamics of a well-localized
electron are used as examples of FDTD application to the case of free
electrons.


title:
Magnetic Structure and Interactions in the Quasi-1D Antiferromagnet
  CaV$_2$O$_4$

abstract:
  CaV$_2$O$_4$ is a spin-1 antiferromagnet, where the magnetic vanadium ions
are arranged on quasi-one-dimensional (1D) zig-zag chains with potentially
frustrated antiferromagnetic exchange interactions. High temperature
susceptibility and single-crystal neutron diffraction measurements are used to
deduce the non-collinear magnetic structure, dominant exchange interactions and
orbital configurations. The results suggest that at high temperatures
CaV$_2$O$_4$ behaves as a Haldane chain, but at low temperatures, orbital
ordering lifts the frustration and it becomes a spin-1 ladder.


title: HX-POL - A Balloon-Borne Hard X-Ray Polarimeter

abstract:
  We report on the design and estimated performance of a balloon-borne hard
X-ray polarimeter called HX-POL. The experiment uses a combination of Si and
Cadmium Zinc Telluride detectors to measure the polarization of 50 keV-400 keV
X-rays from cosmic sources through the dependence of the angular distribution
of Compton scattered photons on the polarization direction. On a one-day
balloon flight, HX-POL would allow us to measure the polarization of bright
Crab-like sources for polarization degrees well below 10%. On a longer (15-30
day) flight from Australia or Antarctica, HX-POL would be be able to measure
the polarization of bright galactic X-ray sources down to polarization degrees
of a few percent. Hard X-ray polarization measurements provide unique venues
for the study of particle acceleration processes by compact objects and
relativistic outflows. In this paper, we discuss the overall instrument design
and performance. Furthermore, we present results from laboratory tests of the
Si and CZT detectors.


title: Resonance Zones and Lobe Volumes for Volume-Preserving Maps

abstract:
  We study exact, volume-preserving diffeomorphisms that have heteroclinic
connections between a pair of normally hyperbolic invariant manifolds. We
develop a general theory of lobes, showing that the lobe volume is given by an
integral of a generating form over the primary intersection, a subset of the
heteroclinic orbits. Our definition reproduces the classical action formula in
the planar, twist map case. For perturbations from a heteroclinic connection,
the lobe volume is shown to reduce, to lowest order, to a suitable integral of
a Melnikov function.


title: Stability of graph communities across time scales

abstract:
  The complexity of biological, social and engineering networks makes it
desirable to find natural partitions into communities that can act as
simplified descriptions and provide insight into the structure and function of
the overall system. Although community detection methods abound, there is a
lack of consensus on how to quantify and rank the quality of partitions. We
show here that the quality of a partition can be measured in terms of its
stability, defined in terms of the clustered autocovariance of a Markov process
taking place on the graph. Because the stability has an intrinsic dependence on
time scales of the graph, it allows us to compare and rank partitions at each
time and also to establish the time spans over which partitions are optimal.
Hence the Markov time acts effectively as an intrinsic resolution parameter
that establishes a hierarchy of increasingly coarser clusterings. Within our
framework we can then provide a unifying view of several standard partitioning
measures: modularity and normalized cut size can be interpreted as one-step
time measures, whereas Fiedler's spectral clustering emerges at long times. We
apply our method to characterize the relevance and persistence of partitions
over time for constructive and real networks, including hierarchical graphs and
social networks. We also obtain reduced descriptions for atomic level protein
structures over different time scales.


title: SIRS dynamics on random networks: simulations and analytical models

abstract:
  The standard pair approximation equations (PA) for the
Susceptible-Infective-Recovered-Susceptible (SIRS) model of infection spread on
a network of homogeneous degree $k$ predict a thin phase of sustained
oscillations for parameter values that correspond to diseases that confer long
lasting immunity. Here we present a study of the dependence of this oscillatory
phase on the parameter $k$ and of its relevance to understand the behaviour of
simulations on networks. For $k=4$, we compare the phase diagram of the PA
model with the results of simulations on regular random graphs (RRG) of the
same degree. We show that for parameter values in the oscillatory phase, and
even for large system sizes, the simulations either die out or exhibit damped
oscillations, depending on the initial conditions. This failure of the standard
PA model to capture the qualitative behaviour of the simulations on large RRGs
is currently being investigated.


title:
Stationary solutions for the parity-even sector of the CPT-even and
  Lorentz-covariance-violating term of the standard model extension

abstract:
  In this work, we focus on some properties of the parity-even sector of the
CPT-even electrodynamics of the standard model extension. We analyze how the
six non-birefringent terms belonging to this sector modify the static and
stationary classical solutions of the usual Maxwell theory. We observe that the
parity-even terms do not couple the electric and magnetic sectors (at least in
the stationary regime). The Green's method is used to obtain solutions for the
field strengths E and B at first order in the Lorentz- covariance-violating
parameters. Explicit solutions are attained for point-like and spatially
extended sources, for which a dipolar expansion is achieved. Finally, it is
presented an Earth-based experiment that can lead (in principle) to an upper
bound on the anisotropic coefficients as stringent as
$(\widetilde{\kappa}_{e-}) ^{ij}<2.9\times10^{-20}.$


title:
Long-Term Optical Monitoring of Eta Carinae. Multiband light curves for
  a complete orbital period

abstract:
  The periodicity of 5.5 years for some observational events occurring in Eta
Carinae manifests itself across a large wavelength range and has been
associated with its binary nature. These events are supposed to occur when the
binary components are close to periastron. To detect the previous periastron
passage of Eta Car in 2003, we started an intensive, ground-based, optical,
photometric observing campaign. We continued observing the object to monitor
its photometric behavior and variability across the entire orbital cycle. Our
observation program consisted of daily differential photometry from CCD images,
which were acquired using a 0.8 m telescope and a standard BVRI filter set at
La Plata Observatory. The photometry includes the central object and the
surrounding Homunculus nebula. We present up-to-date results of our observing
program, including homogeneous photometric data collected between 2003 and
2008. Our observations demonstrated that Eta Car has continued increasing in
brightness at a constant rate since 1998. In 2006, it reached its brightest
magnitude (V ~ 4.7) since about 1860s. The object then suddenly reverted its
brightening trend, fading to V = 5.0 at the beginning of 2007, and has
maintained a quite steady state since then. We continue the photometric
monitoring of Eta Car in anticipation of the next "periastron passage",
predicted to occur at the beginning of 2009.


title: High yield fusion in a Staged Z-pinch

abstract:
  We simulate fusion in a Z-pinch; where the load is a xenon-plasma liner
imploding onto a deuterium-tritium plasma target and the driver is a 2 MJ, 17
MA, 95 ns risetime pulser. The implosion system is modeled using the dynamic,
2-1/2 D, radiation-MHD code, MACH2. During implosion a shock forms in the Xe
liner, transporting current and energy radially inward. After collision with
the DT, a secondary shock forms pre-heating the DT to several hundred eV.
Adiabatic compression leads subsequently to a fusion burn, as the target is
surrounded by a flux-compressed, intense, azimuthal-magnetic field. The
intense-magnetic field confines fusion $\alpha$-particles, providing an
additional source of ion heating that leads to target ignition. The target
remains stable up to the time of ignition. Predictions are for a neutron yield
of $3.0\times 10^{19}$ and a thermonuclear energy of 84 MJ, that is, 42 times
greater than the initial, capacitor-stored energy.


title: Krull dimension for limit groups IV: Adjoining roots

abstract:
  This is the fourth and last paper in a sequence on Krull dimension for limit
groups, answering a question of Z. Sela. In it we finish the proof, analyzing
limit groups obtained from other limit groups by adjoining roots. We generalize
our work on Scott complexity and adjoining roots from the previous paper in the
sequence to the category of limit groups.


title:
Least-Squares Approximation by Elements from Matrix Orbits Achieved by
  Gradient Flows on Compact Lie Groups

abstract:
  Let $S(A)$ denote the orbit of a complex or real matrix $A$ under a certain
equivalence relation such as unitary similarity, unitary equivalence, unitary
congruences etc. Efficient gradient-flow algorithms are constructed to
determine the best approximation of a given matrix $A_0$ by the sum of matrices
in $S(A_1), ..., S(A_N)$ in the sense of finding the Euclidean least-squares
distance $$\min \{\|X_1+ ... + X_N - A_0\|: X_j \in S(A_j), j = 1, >..., N\}.$$
Connections of the results to different pure and applied areas are discussed.


title: Dissipative Bjorken hydrodynamics from an AdS Schwarzschild black hole

abstract:
  We discuss the derivation of dissipative Bjorken hydrodynamics from a
Schwarzschild black hole in asymptotically AdS spacetime of arbitrary dimension
in the limit of large longitudinal proper time $\tau$. Using an appropriate
slicing near the boundary, we calculate the Schwarzschild metric to
next-to-next-to-leading order in the large $\tau$ expansion as well as the dual
stress-energy tensor on the boundary via holographic renormalization. At
next-to-next-to-leading order, it is necessary to perturb the Schwarzschild
metric in order to maintain boost invariance. The perturbation has a power law
time dependence and leads to the same value of the ratio of viscosity to
entropy density, $1/(4\pi)$, as in the case of sinusoidal perturbations. Our
results are in agreement with known time-dependent asymptotic solutions of the
Einstein equations in five dimensions.


title: Recent progress in Hamiltonian light-front QCD

abstract:
  Hamiltonian light-front quantum field theory constitutes a framework for the
non-perturbative solution of invariant masses and correlated parton amplitudes
of self-bound systems. By choosing light-front gauge and adopting a basis
function representation, we obtain a large, sparse, Hamiltonian matrix for mass
eigenstates of gauge theories that is solvable by adapting the ab initio
no-core methods of nuclear many-body theory. Full covariance is recovered in
the continuum limit, the infinite matrix limit. We outline our approach and
discuss the computational challenges.


title:
Overview and Validation of the CEM and LAQGSM Event Generators for
  MCNP6, MCNPX, and MARS15

abstract:
  A brief description of the IntraNuclear cascade, preequilibrium, evaporation,
fission, coalescence, and Fermi breakup models used by the last versions of our
CEM and LAQGSM event generators is presented, with a focus on our latest
development of all these models. The recently developed "S" and "G" versions of
our codes, that consider multifragmentation of nuclei formed after the
preequilibrium stage of reactions when their excitation energy is above 2A MeV
using the Statistical Multifragmentation Model (SMM) code by Botvina et al.
("S" stands for SMM) and the fission-like binary-decay model GEMINI by Charity
("G" stands for GEMINI), respectively, are overviewed as well. Examples of
benchmarking our models against a large variety of experimental data on
particle-particle, particle nucleus, and nucleus-nucleus reactions, involving
some very recent measurements of interest to accelerator radiation induced
activation, are discussed.


title: Spectral Modeling of Rotating Turbulent Flows

abstract:
  We test a subgrid-scale spectral model of rotating turbulent flows against
direct numerical simulations. The particular case of Taylor-Green forcing at
large scale is considered, a configuration that mimics the flow between two
counter rotating disks as often used in the laboratory. We perform computations
in the presence of moderate rotation down to Rossby numbers of 0.03, as can be
encountered in the Earth atmosphere and oceans. We provide several classical
measures of the degree of anisotropy of the small scales of the flows under
study and conclude that an isotropic model may suffice at moderate Rossby
numbers. The model, developed previously (Baerenzung et al., Phys. Rev. E 77,
046303 (2008)), incorporates eddy viscosity that depends dynamically on the
inertial index of the energy spectrum, as well as eddy noise. We show that the
model reproduces satisfactorily all large-scale properties of the direct
numerical simulations up to Reynolds numbers of the order of 10000 and for long
times after the onset of the inverse cascade of energy at low Rossby number.


title:
Design of flexible ultrahigh-Q microcavities in diamond-based photonic
  crystal slabs

abstract:
  We design extremely flexible ultrahigh-Q diamond-based double-heterostructure
photonic crystal slab cavities by modifying the refractive index of the
diamond. The refractive index changes needed for ultrahigh-Q cavities with $Q ~
10^7$, are well within what can be achieved ($\Delta n \sim 0.02$). The cavity
modes have relatively small volumes $V<2 (\lambda /n)^3$, making them ideal for
cavity quantum electro-dynamic applications. Importantly for realistic
fabrication, our design is flexible because the range of parameters, cavity
length and the index changes, that enables an ultrahigh-Q is quite broad.
Furthermore as the index modification is post-processed, an efficient technique
to generate cavities around defect centres is achievable, improving prospects
for defect-tolerant quantum architectures.


title: Stability of the Ricci Yang-Mills flow at Einstein Yang-Mills metrics

abstract:
  Let $P$ be a principal U(1)-bundle over a closed manifold $M$. On $P$, one
can define a modified version of the Ricci flow called the Ricci Yang-Mills
flow, due to these equations being a coupling of Ricci flow and the Yang-Mills
heat flow. We use maximal regularity theory and ideas of Simonett concerning
the asymptotic behavior of abstract quasilinear parabolic partial differential
equations to study the stability of the volume-normalized Ricci Yang-Mills flow
at Einstein Yang-Mills metrics in dimension two. In certain cases, we show the
presence of a center manifold of fixed points, while in others, we show the
existence of an asymptotically stable fixed point.


title:
A full vectorial model for pulse propagation in emerging waveguides with
  subwavelength structures part I: Kerr nonlinearity

abstract:
  The propagation of pulses through waveguides with subwavelength features,
inhomogeneous transverse structure, and high index contrast cannot be described
accurately using existing models in the presence of nonlinear effects. Here we
report the development of a generalised full vectorial model of nonlinear pulse
propagation and demonstrate that, unlike the standard pulse propagation
formulation, the z-component of guided modes plays a key role for these new
structures, and results in generalised definitions of the nonlinear coefficient
$\gamma,$ $A_{eff}$, and mode orthognality. While new definitions reduce to
standard definitions in some limits, significant differences are predicted,
including a factor of $\sim2$ higher value for $\gamma$, for emerging
waveguides and microstructured fibers.


title:
Local Well-posedness for dispersion generalized Benjamin-Ono equations
  in Sobolev spaces

abstract:
  We prove that the Cauchy problem for the dispersion generalized Benjamin-Ono
equation \[\partial_t u+|\partial_x|^{1+\alpha}\partial_x u+uu_x=0,\
u(x,0)=u_0(x),\] is locally well-posed in the Sobolev spaces $H^s$ for
$s>1-\alpha$ if $0\leq \alpha \leq 1$. The new ingredient is that we develop
the methods of Ionescu, Kenig and Tataru \cite{IKT} to approach the problem in
a less perturbative way, in spite of the ill-posedness results of Molinet, Saut
and Tzvetkovin \cite{MST}. Moreover, as a bi-product we prove that if $0<\alpha
\leq 1$ the corresponding modified equation (with the nonlinearity $\pm uuu_x$)
is locally well-posed in $H^s$ for $s\geq 1/2-\alpha/4$.


title:
A light scalar as the messenger of electroweak and flavor symmetry
  breaking

abstract:
  We propose a new framework for understanding the hierarchies of fermion
masses and mixings. The masses and mixings of all Standard Model (SM) charged
fermions other than top arise from higher dimensional operators involving a
messenger scalar S and flavon scalars F_i. The flavons spontaneously break SM
flavor symmetries at around the TeV scale. The SM singlet scalar S couples
directly to the Higgs H and spontaneously breaks another U(1) at the
electroweak scale. At the TeV scale, SM quarks and charged leptons have
renormalizable couplings to S, but not to H or F_i. These couplings involve new
heavy vectorlike fermions. Integrating out these fermions produces a pattern of
higher dimensional operators that reproduce the observed hierarchies of the SM
masses and mixings in terms of powers of the "little hierarchy": the ratio of
the electroweak scale to the flavor-breaking scale.
  The framework has important phenomenological implications. Flavor-changing
neutral currents are within experimental limits but D^0 mixing and B_s->mu+mu-
could be close to current sensitivities. The neutral scalar s of the messenger
field mixes with the light Higgs of the SM, which can have strong effects on
Higgs decay branching fractions. The s mass eigenstate may be lighter than the
Higgs, and could be detected at the Tevatron or the LHC.


title: Dynamics of interacting dark energy

abstract:
  Dark energy and dark matter are only indirectly measured via their
gravitational effects. It is possible that there is an exchange of energy
within the dark sector, and this offers an interesting alternative approach to
the coincidence problem. We consider two broad classes of interacting models
where the energy exchange is a linear combination of the dark sector densities.
The first class has been previously investigated, but we define new variables
and find a new exact solution, which allows for a more direct, transparent and
comprehensive analysis. The second class has not been investigated in general
form before. We give general conditions on the parameters in both classes to
avoid unphysical behavior (such as negative energy densities).


title:
An accretion disc-corona model for X-ray spectra of active galactic
  nuclei

abstract:
  The hard X-ray emission of active galactic nuclei (AGN) is believed to
originate from the hot coronae above the cold accretion discs. The hard X-ray
spectral index is found to be correlated with the Eddington ratio, and the hard
X-ray bolometric correction factor L_bol/L_x increases with the Eddington
ratio. The Compton reflection is also found to be correlated with the hard
X-ray spectral index. These observational features provide very useful
constraints on the accretion disc-corona model for AGN. We construct an
accretion disc-corona model and calculate the spectra with different magnetic
stress tensors in the cold discs, in which the corona is assumed to be heated
by the reconnection of the magnetic fields generated by buoyancy instability in
the cold accretion disc. Our calculations show that the magnetic stress tensor
\alpha p_gas fails to explain all these observational features, while \alpha
p_tot always leads to constant L_bol/L_x independent of the Eddington ratio.
The resulted spectra of the disc-corona systems with \alpha (p_gas p_tot)^1/2
show that both the hard X-ray spectral index and the hard X-ray bolometric
correction factor L_bol/L_x increase with the Eddington ratio, which are
qualitatively consistent with the observations. We find that the disc-corona
model is unable to reproduce the observed very hard X-ray continuum emission
from the sources accreting at low rates, which may imply the different
accretion mode in these low luminosity sources. We suggest that the disc-corona
system transits to an advection-dominated accretion flow+disc corona system at
low accretion rates, which may be able to explain all the above-mentioned
correlations.


title: Whitehead products in function spaces: Quillen model formulae

abstract:
  We study Whitehead products in the rational homotopy groups of a general
component of a function space. For the component of any based map f: X \to Y,
in either the based or free function space, our main results express the
Whitehead product directly in terms of the Quillen minimal model of f. These
results follow from a purely algebraic development in the setting of chain
complexes of derivations of differential graded Lie algebras, which is of
interest in its own right. We apply the results to study the Whitehead length
of function space components.


title:
Inadequacy of a classical interpretation of quantum projective
  measurements via Wigner functions

abstract:
  We study the possibility of giving a classical interpretation to quantum
projective measurements for a particle described by a pure Gaussian state whose
Wigner function is non-negative. We analyze the case of a projective
measurement which gives rise to a proper Wigner function, i.e., taking on, as
its values, the eigenvalues of the projector. We find that, despite having this
property, this kind of projector produces a state whose Wigner function ceases
to be non-negative and hence precludes its interpretation as a classical
probability density. We also study the general case in which the projected
state has a non-negative Wigner function; but then we find that the Wigner
function of the projector is not a proper one. Thus, we conclude that a
non-negative Wigner function is inadequate to serve as a hidden variable model
for quantum processes in which projective measurements take place.


title:
Multiple Parameter Function Approaches to the Equations of Dynamic
  Convection in a Sea

abstract:
  One of the most important topics in geophysics is to study convection in a
sea. Based on the algebraic characteristics of the equations of dynamic
convection in a sea, we introduce various schemes with multiple parameter
functions to solve these equations and obtain families of new explicit exact
solutions with multiple parameter functions. Moreover, symmetry transformations
are used to simplify our arguments.

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


title: High velocity water maser emission from the Post-AGB star OH 009.1-0.4

abstract:
  Observations of H$_2$O masers towards the post-AGB star and water fountain
source OH 009.1--0.4 were made as part of HOPS (The H$_2$O southern galactic
Plane Survey), with the Mopra radiotelescope. Together with followup
observations using the Australia Telescope Compact Array (ATCA), we have
identified H$_2$O maser emission over a velocity spread of nearly 400km/s
(--109 to +289km/s). This velocity spread appears to be the largest of any
known maser source in our Galaxy. High resolution observations with the ATCA
indicate the maser emission is confined to a region $0\farcs3 \times 0\farcs3$
and shows weak evidence for a separation of the red- and blueshifted maser
spots. We are unable to determine if the water fountain is projected along the
line of sight, or is inclined, but either way OH 009.1--0.4 is an interesting
source, worthy of followup observations.


title: Quadratic-Argument Approach to the Davey-Stewartson Equations

abstract:
  The Davey-Stewartson equations are used to describe the long time evolution
of a three-dimensional packets of surface waves. Assuming that the argument
functions are quadratic in spacial variables, we find in this paper various
exact solutions modulo the most known symmetry transformations for the
Davey-Stewartson equations.

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


title: Poincare Invariant Three-Body Scattering

abstract:
  Relativistic Faddeev equations for three-body scattering are solved at
arbitrary energies in terms of momentum vectors without employing a partial
wave decomposition. Relativistic invariance is incorporated withing the
framework of Poincar\'e invariant quantum mechanics. Based on a Malfliet-Tjon
interaction, observables for elastic and breakup scattering are calculated and
compared to non-relativistic ones.


title: The Challenge of Modelling Galactic Disks

abstract:
  Detailed models of galactic disk formation and evolution require knowledge
about the initial conditions under which disk galaxies form, the boundary
conditions that affect their secular evolution and the micro-physical processes
that drive the multi-phase interstellar medium and regulate the star formation
history. Unfortunately, up to now, most of these ingredients are still poorly
understood. The challenge therefore is to, despite this caveat, construct
realistic models of galactic disks with predictive power. This short review
will summarize some problems related to numerical simulations of galactic disk
formation and evolution.


title: Possible d0 ferromagnetism in MgO doped with nitrogen

abstract:
  We study the possibility of d0 ferromagnetism in the compound
  MgO doped with nitrogen (N). The Haldane-Anderson impurity model is
formulated within the tight-binding approximation for determining the host
band-structure and the impurity-host hybridization. Using the quantum Monte
Carlo technique, we observe a finite local moment for an N impurity, and
long-range ferromagnetic correlations between two N impurities. The
ferromagnetic correlations are strongly influenced by the impurity bound state.
When the ferromagnetic correlation between a pair of impurities is mapped onto
the isotropic Heisenberg model for two spin-1/2 particles, the effective
exchange constant J12 is found to increase with increasing temperature. Similar
temperature dependence of J12 is also obtained in other diluted magnetic
semiconductors, such as zincblende ZnO doped with Mn. The temperature
dependence of J12 suggests that the mapping of the full Hamiltonian onto the
spin Hamiltonian cannot fully describe the magnetic correlations for the
diluted magnetic semiconductors at least in the limit of low impurity spin.


title: Macroscopic reduction for stochastic reaction-diffusion equations

abstract:
  The macroscopic behavior of dissipative stochastic partial differential
equations usually can be described by a finite dimensional system. This article
proves that a macroscopic reduced model may be constructed for stochastic
reaction-diffusion equations with cubic nonlinearity by artificial separating
the system into two distinct slow-fast time parts. An averaging method and a
deviation estimate show that the macroscopic reduced model should be a
stochastic ordinary equation which includes the random effect transmitted from
the microscopic timescale due to the nonlinear interaction. Numerical
simulations of an example stochastic heat equation confirms the predictions of
this stochastic modelling theory. This theory empowers us to better model the
long time dynamics of complex stochastic systems.


title:
Collective excitations and instabilities in multi-layer stacks of
  dipolar condensates

abstract:
  We analyze theoretically the collective mode dispersion in multi-layer stacks
of two dimensional dipolar condensates and find a strong enhancement of the
roton instability. We discuss the interplay between the dynamical instability
and roton softening for moving condensates. We use our results to analyze the
decoherence rate of Bloch oscillations for systems in which the s-wave
scattering length is tuned close to zero using Feshbach resonance. Our results
are in qualitative agreement with recent experiments of Fattori {\it et al.} on
$^{39}$K atoms.


title: Combinatorial study on the group of parity alternating permutations

abstract:
  The combinatorial theory for the set of parity alternating permutations is
expounded. In view of the numbers of ascents and inversions, several
enumerative aspects of the set are investigated. In particular, it is shown
that signed Eulerian numbers have intimate relationships to the set.


title: Conformal Field Theory and Algebraic Structure of Gauge Theory

abstract:
  We consider various homotopy algebras related to Yang-Mills theory and
two-dimensional conformal field theory (CFT). Our main objects of study are
Yang-Mills $L_{\infty}$ and $C_{\infty}$ algebras and their relation to the
certain algebraic structures of Lian-Zuckerman type in CFT. We also consider
several examples of algebras related to gauge theory, involving first order
formulations and gauge theories with matter fields.


title: Technicolor Signals at the LHC

abstract:
  In this lecture I give an introduction to technicolor and extended
technicolor theories. I discuss the issues models of dynamical electroweak
symmetry breaking struggle with and propose how non QCD-like dynamics, such as
a `walking' or nearly-conformal technicolor coupling, can invalidate many
conventional arguments against technicolor. I provide a short discussion of
AdS/CFT-inspired extra-dimensional (Higgsless) models and their similarities
and differences with older 4D technicolor models. To conclude, a summary of
some possible LHC signatures is given.


title: Explaining B \to K pi anomaly with non-universal Z' boson

abstract:
  We study the effect of non-universal $Z'$ boson in the decay modes $B \to K
\pi$. In the standard model these modes receive dominant contributions from $b
\to s$ QCD penguins. Therefore, in this limit one expects $S_{\pi^0 K^0}
\approx \sin 2 \beta $, $A_{\pi^0 K^0} \approx 0$ and $A_{\pi^0 K^-} \approx
A_{\pi^+ K^-}$. The corrections due to the presence of small non-penguin
contributions is found to yield $S_{\pi^0 K^0} > \sin 2 \beta $ and $\Delta
A_{CP}(K \pi) \simeq 2.5 %$. However, the measured value of $S_{\pi^0 K^0}$ is
less than $ \sin 2 \beta $ and $\Delta A_{CP}(K \pi) \simeq 15 %$. We show the
model with a non-universal $Z'$ boson can successfully explain these anomalies.


title:
Identification of parameters underlying emotions and a classification of
  emotions

abstract:
  The standard classification of emotions involves categorizing the expression
of emotions. In this paper, parameters underlying some emotions are identified
and a new classification based on these parameters is suggested.


title: Molecular Signatures in the Near Infrared Dayside Spectrum of HD 189733b

abstract:
  We have measured the dayside spectrum of HD 189733b between 1.5 and 2.5
microns using the NICMOS instrument on the Hubble Space Telescope. The emergent
spectrum contains significant modulation, which we attribute to the presence of
molecular bands seen in absorption. We find that water (H2O), carbon monoxide
(CO), and carbon dioxide (CO2) are needed to explain the observations, and we
are able to estimate the mixing ratios for these molecules. We also find
temperature decreases with altitude in the ~0.01 < P < ~1 bar region of the
dayside near-infrared photosphere and set an upper limit to the dayside
abundance of methane (CH4) at these pressures.


title: TeV neutrinos and gamma rays from pulsars

abstract:
  Recent studies suggest that pulsars could be strong sources of TeV muon
neutrinos provided positive ions are accelerated by pulsar polar caps to PeV
energies. In such a situation muon neutrinos are produced through the delta
resonance in interactions of pulsar accelerated ions with its thermal radiation
field. High energy gamma rays also should be produced simultaneously in pulsar
environment as both charged and neutral pions are generated in the interactions
of energetic hadrons with the ambient photon fields. Here we estimate TeV gamma
ray flux at Earth from few nearby young pulsars. When compared with the
observations we find that proper consideration of the effect of polar cap
geometry in flux calculation is important. Incorporating such an effect we
obtain the (revised) event rates at Earth due to few potential nearby pulsars.
The results suggest that pulsars are unlikely to be detected by the upcoming
neutrino telescopes. We also estimate TeV gamma ray and neutrino fluxes from
pulsar nebulae for the adopted model of particle acceleration.


title:
Gas Properties and Implications for Galactic Star Formation in Numerical
  Models of the Turbulent, Multiphase ISM

abstract:
  Using numerical simulations of galactic disks resolving scales from ~1 to
several hundred pc, we investigate dynamical properties of the multiphase ISM
with turbulence driven by star formation feedback. We focus on HII region
effects by applying intense heating in dense, self-gravitating regions. Our
models are two-dimensional radial-vertical slices through the disk, and include
sheared background rotation, vertical stratification, heating and cooling to
yield temperatures T~10-10^4K, and thermal conduction. We separately vary the
gas surface density Sigma, the stellar volume density rho_*, and the local
angular rotation rate Omega to explore environmental dependencies, and analyze
the steady-state properties of each model. Among other statistics, we evaluate
turbulent amplitudes, virial ratios, Toomre Q parameters including turbulence,
and the mass fractions at different densities. We find that the dense gas
(n>100 cm^-3) has turbulence levels similar to observed GMCs and virial ratios
~1-2. The Toomre Q parameter in dense gas reaches near unity, demonstrating
self-regulation via turbulent feedback. We also test how the star formation
rate Sigma_SFR depends on Sigma, rho_*, and Omega. Under the assumption that
the star formation rate is proportional to the mass at densities above n_th
divided by the free-fall time at that threshold, we find that Sigma_SFR varies
as Sigma^(1+p) with 1+p ~ 1.2-1.4 when n_th=10^2 or 10^3 cm^-3, consistent with
observations. Estimated star formation rates based on large-scale properties
(the orbital time, the Jeans time, or the free-fall time at the
vertically-averaged density) however depart from rates computed using the dense
gas mass, indicating that resolving the ISM structure in galactic disks at
scales <<H is necessary for accurate predictions of the star formation rate.


title:
Electron acceleration at a low-Mach-number perpendicular collisionless
  shock

abstract:
  A full particle simulation study is carried out on the electron acceleration
at a collisionless, relatively low Alfven Mach number (M_A=5), perpendicular
shock. Recent self-consistent hybrid shock simulations have demonstrated that
the shock front of perpendicular shocks has a dynamic rippled character along
the shock surface of low-Mach-number perpendicular shocks. In this paper, the
effect of the rippling of perpendicular shocks on the electron acceleration is
examined by means of large-scale (ion-scale) two-dimensional full particle
simulations. It has been shown that a large-amplitude electric field is excited
at the shock front in association with the ion-scale rippling, and that
reflected ions are accelerated upstream at a localized region where the
shock-normal electric field of the rippled structure is polarized upstream. The
current-driven instability caused by the highly-accelerated reflected ions has
a high growth rate to large-amplitude electrostatic waves. Energetic electrons
are then generated by the large-amplitude electrostatic waves via electron
surfing acceleration at the leading edge of the shock transition region. The
present result suggests that the electron surfing acceleration is also a common
feature at low-Mach-number perpendicular collisionless shocks.


title:
Pressure Relations and Vertical Equilibrium in the Turbulent, Multiphase
  ISM

abstract:
  We use numerical simulations of turbulent, multiphase, self-gravitating gas
orbiting in model disk galaxies to study the relationships among pressure, the
vertical gas distribution, and the ratio of dense to diffuse gas. We show that
the disk height and mean midplane pressure are consistent with effective
hydrostatic equilibrium, provided that the turbulent vertical velocity
dispersion and gas self-gravity are included. Mass-weighted pressures are an
order of magnitude higher than the midplane pressure because self-gravity
concentrates gas and increases the pressure in clouds. We also investigate the
ratio Rmol=M(H2)/M(HI) for our simulations. Blitz and Rosolowsky (2006) showed
that Rmol is proportional to the estimated midplane pressure. For model series
in which the epicyclic frequency, kappa, and gas surface density, Sigma, are
proportional, we recover the empirical relation. For other model series in
which kappa and Sigma are independent, the midplane pressure and Rmol are not
well correlated. We conclude that the molecular fraction -- and star formation
rate -- of a galactic disk inherently depends on its rotational state, not just
the local values of Sigma and the stellar density rho*. The empirical
correlation between Rmol and midplane pressure implies that the "environmental
parameters" kappa, Sigma, and rho* are interdependent in real galaxies,
presumably as a consequence of evolution toward states with Toomre Q near
unity. We note that Rmol in static models far exceeds both the values in our
turbulent simulations and observed values, implying that turbulence is crucial
to obtaining a realistic molecular fraction in the ISM.


title: Time-dependent Sobolev inequality along the Ricci flow

abstract:
  In this article we get a time-dependent Sobolev inequality along the Ricci
flow which generalizes the earlier results of Zhang, Ye, Hsu. As an application
of the time-dependent Sobolev inequality, we also get a growth of the ratio of
bob-collapsing along the Ricci flow.


title:
New prediction of extragalactic GeV gamma-ray emission from radio lobes
  of young AGN jets

abstract:
  We present a new prediction of GeV $\gamma$-ray emission from radio lobes of
young AGN jets. In the previous work of Kino et al. (2007), MeV $\gamma$-ray
bremsstrahlung emission was predicted from young cocoons/radio-lobes in the
regime of no coolings. In this study, we include cooling effects of
bremsstrahlung emission and adiabatic loss. With the initial conditions
determined by observed young radio lobes, we solve a set of equations
describing the expanding lobe evolution. Then we find that the lobes initially
have electron temperature of $\sim$GeV, and they cool down to $\sim$MeV by the
adiabatic loss. Correspondingly, the lobes initially yield bright
bremsstrahlung luminosity in $\sim$GeV range and they fade out. We estimate
these $\gamma$-ray emissions and show that nearby young radio lobes could be
detected with Fermi Gamma-ray Space Telescope.


title: Transverse field-induced effects in carbon nanotubes

abstract:
  We investigate the properties of conduction electrons in single-walled
armchair carbon nanotubes (SWNT) in the presence of both transverse electric
and magnetic fields. We find that these fields provide a controlled means of
tuning low-energy band structure properties such as inducing gaps in the
spectrum, breaking various symmetries and altering the Fermi velocities. We
show that the fields can strongly affect electron-electron interaction,
yielding tunable Luttinger liquid physics, the possibility of spin-charge-band
separation, and a competition between spin-density-wave and charge-density-wave
order. For short tubes, the fields can alter boundary conditions and associated
single-particle level spacings as well as quantum dot behavior.


title:
Effect of oxygen concentration on the structural and magnetic properties
  of LaRh1/2Mn1/2O3 thin films

abstract:
  Epitaxial LaRh1/2Mn1/2O3 thin films have been grown on (001)-oriented LaAlO3
and SrTiO3 substrates using pulsed laser deposition. The optimized thin film
samples are semiconducting and ferromagnetic with a Curie temperature close to
100 K, a coercive field of 1200 Oe, and a saturation magnetization of 1.7muB
per formula unit. The surface texture, structural, electrical, and magnetic
properties of the LaRh1/2Mn1/2O3 films was examined as a function of the oxygen
concentration during deposition. While an elevated oxygen concentration yields
thin films with optimal magnetic properties, slightly lower oxygen
concentrations result in films with improved texture and crystallinity.


title:
Quantized meson fields in and out of equilibrium. II: Chiral condensate
  and collective meson excitations

abstract:
  We develop a quantum kinetic theory of the chiral condensate and meson
quasi-particle excitations using the O(N) linear sigma model which describe the
chiral phase transition both in and out of equilibrium in a unified way. A mean
field approximation is formulated in the presence of mesonic quasi-particle
excitations which are described by generalized Wigner functions. It is shown
that in equilibrium our kinetic equations reduce to the gap equations which
determine the equilibrium condensate amplitude and the effective masses of the
quasi-particle excitations, while linearization of transport equations, near
such equilibrium, determine the dispersion relations of the collective mesonic
excitations at finite temperatures. Although all mass parameters for the meson
excitations become at finite temperature, apparently violating the Goldstone
theorem, the missing Nambu-Goldstone modes are retrieved in the collective
excitations of the system as three degenerate phonon-like modes in the
symmetry-broken phase. We show that the temperature dependence of the pole
masses of the collective pion excitations has non-analytic kink behavior at the
threshold of the quasi-particle excitations in the presence of explicit
symmetry breaking interaction.


title: Dileptons and four leptons at Z' resonance in the early stage of the LHC

abstract:
  The LHC era just began. The first discovery at the LHC experiment would be
arguably a new resonance pole at TeV scale, if it exists. While the discovery
of the Z' would be exciting by itself, it may also suggest what other new
physics signals should be looked for while the LHC experiment is still at its
early stage. We argue that the four lepton resonance at the Z' pole is a
well-motivated and promising signal especially in supersymmetry framework,
which can serve as a supersymmetry search scheme even in the early stage of the
LHC experiment.


title:
Infrared Studies of Molecular Shocks in the Supernova Remnant HB21: I.
  Thermal Admixture of Shocked H_2 Gas in the North

abstract:
  We present near- and mid-infrared observations on the shock-cloud interaction
region in the northern part of the supernova remnant HB21, performed with the
InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera
(WIRC) at the Palomar 5 m telescope. The IRC 7 um (S7), 11 um (S11), and 15 um
(L15) band images and the WIRC H2 v = 1 -> 0 S(1) 2.12 um image show similar
shock-cloud interaction features. We chose three representative regions, and
analyzed their IRC emissions through comparison with H2 line emissions of
several shock models. The IRC colors are well explained by the thermal
admixture model of H2 gas--whose infinitesimal H2 column density has a
power-law relation with the temperature T, dN ~ T^-b dT--with n(H2) ~ 10^3
cm^-3, b ~ 3, and N(H2 ;T > 100K) ~ 3x10^20 cm^-2. The derived b value may be
understood by a bow shock picture, whose shape is cycloidal (cuspy) rather than
paraboloidal. However, this picture raises another issue that the bow shocks
must reside within ~0.01 pc size-scale, smaller than the theoretically
expected. Instead, we conjectured a shocked clumpy interstellar medium picture,
which may avoid the sizescale issue while explaining the similar model
parameters. The observed H2 v = 1 -> 0 S(1) intensities are a factor of ~17 -
33 greater than the prediction from the power-law admixture model. This excess
may be attributed to either an extra component of hot H2 gas or to the effects
of collisions with hydrogen atoms, omitted in our power-law admixture model,
both of which would increase the population in the v = 1 level of H2.


title:
A multiplicative formula for structure constants in the cohomology of
  flag varieties

abstract:
  Let G be a complex semi-simple Lie group and let P,Q be a pair of parabolic
subgroups of G such that Q contains P. Consider the flag varieties G/P, G/Q and
Q/P. We show that certain structure constants in H^*(G/P) with respect to the
Schubert basis can be written as a product of structure constants coming from
H^*(G/Q) and H^*(Q/P) in a very natural way. The primary application is to
compute Levi-movable structure constants defined by Belkale and Kumar. We also
give a generalization of this product formula in the branching Schubert
calculus setting.


title:
Dependence Balance Based Outer Bounds for Gaussian Networks with
  Cooperation and Feedback

abstract:
  We obtain new outer bounds on the capacity regions of the two-user multiple
access channel with generalized feedback (MAC-GF) and the two-user interference
channel with generalized feedback (IC-GF). These outer bounds are based on the
idea of dependence balance which was proposed by Hekstra and Willems [1]. To
illustrate the usefulness of our outer bounds, we investigate three different
channel models. We first consider a Gaussian MAC with noisy feedback (MAC-NF),
where transmitter $k$, $k=1,2$, receives a feedback $Y_{F_{k}}$, which is the
channel output $Y$ corrupted with additive white Gaussian noise $Z_{k}$. As the
feedback noise variances become large, one would expect the feedback to become
useless, which is not reflected by the cut-set bound. We demonstrate that our
outer bound improves upon the cut-set bound for all non-zero values of the
feedback noise variances. Moreover, in the limit as $\sigma_{Z_{k}}^{2}\to
\infty$, $k=1,2$, our outer bound collapses to the capacity region of the
Gaussian MAC without feedback. Secondly, we investigate a Gaussian MAC with
user-cooperation (MAC-UC), where each transmitter receives an additive white
Gaussian noise corrupted version of the channel input of the other transmitter
[2]. For this channel model, the cut-set bound is sensitive to the cooperation
noises, but not sensitive enough. For all non-zero values of cooperation noise
variances, our outer bound strictly improves upon the cut-set outer bound.
Thirdly, we investigate a Gaussian IC with user-cooperation (IC-UC). For this
channel model, the cut-set bound is again sensitive to cooperation noise
variances but not sensitive enough. We demonstrate that our outer bound
strictly improves upon the cut-set bound for all non-zero values of cooperation
noise variances.


title:
Spatial Wilson loop in continuum, deconfining SU(2) Yang-Mills
  thermodynamics

abstract:
  The uniquess of the effective actions describing 4D SU(2) and SU(3)
continuum, infinite-volume Yang-Mills thermodynamics in their deconfining and
preconfining phases is made explicit. Subsequently, the spatial string tension
is computed in the approach proposed by Korthals-Altes. This SU(2) calculation
is based on a particular, effective two-loop correction to the pressure needed
for the extraction of the hypothetic number density of isolated and screened
magnetic monopoles or antimonopoles in the deconfining phase. By exponentiating
the exchange of the tree-level massless but one-loop dressed mode within a
quadratic spatial contour of side-length $L$ in the effective theory we
demonstrate that for $L\to\infty$ the Wilson loop exhibits {\sl perimeter} law.
This is in contrast to a rigorous {\sl lattice} result subject to the Wilson
action and for this action valid at sufficiently high temperature. In the
framework of the effective theory there is, however, a regime for small
(spatially unresolved) $L$ were the exponent of the spatial Wilson loop
possesses curvature as a function of $L$.