title: The semiclassical stability of de Sitter spacetime

abstract:
  de Sitter spacetime and Bunch-Davies vacuum are a solution to the
semiclassical Einstein-Schroedinger equations describing the evolution of
spacetime geometry and a massive scalar quantum field with arbitrary coupling
to curvature. The stability of this solution is proven by calculating the
renormalized energy momentum tensor expectation value for small spatially
homogeneous deviations from the de Sitter - Bunch-Davies system and solving the
linearized backreaction problem. A renormalization scheme is developed. All
momentum integrations are carried out analytically. The general solution is
given in terms of its Laplace transform. It contains only two artificial
instabilities: a constant gauge mode and an instability on the Planck time
scale lying outside of the scope of our semiclassical theory.


title: Anick's fibration and the odd primary homotopy exponent of spheres

abstract:
  For primes p>=3, Cohen, Moore, and Neisendorfer showed that the exponent of
the p-torsion in the homotopy groups of S^2n+1 is p^n. This was obtained as a
consequence of a thorough analysis of the homotopy theory of Moore spaces.
Anick further developed this for p>=5 by constructing a homotopy fibration
S^2n-1 --> T^2n+1(p^r) --> Loop S^2n+1 whose connecting map is degree p^r on
the bottom cell. A much simpler construction of such a fibration for p>=3 was
given by Gray and the author using new methods. In this paper the new methods
are used to start over, first constructing Anick's fibration for p>=3, and then
using it to obtain the exponent result for spheres.


title:
Influence of Mo on the Fe:Mo:C nano-catalyst thermodynamics for
  single-walled carbon nanotube growth

abstract:
  We explore the role of Mo in Fe:Mo nanocatalyst thermodynamics for
low-temperature chemical vapor deposition growth of single walled carbon
nanotubes (SWCNTs). By using the size-pressure approximation and ab initio
modeling, we prove that for both Fe-rich (~80% Fe or more) and Mo-rich (~50% Mo
or more) Fe:Mo clusters, the presence of carbon in the cluster causes
nucleation of Mo2C. This enhances the activity of the particle since it
releases Fe, which is initially bound in a stable Fe:Mo phase, so that it can
catalyze SWCNT growth. Furthermore, the presence of small concentrations of Mo
reduce the lower size limit of low-temperature steady-state growth from ~0.58nm
for pure Fe particles to ~0.52nm. Our ab initio-thermodynamic modeling explains
experimental results and establishes a new direction to search for better
catalysts.


title:
Transiting exoplanets from the CoRoT space mission II. CoRoT-Exo-2b: A
  transiting planet around an active G star

abstract:
  Context. The CoRoT mission, a pioneer in exoplanet searches from space, has
completed its first 150 days of continuous observations of ~12000 stars in the
galactic plane. An analysis of the raw data identifies the most promising
candidates and triggers the ground-based follow-up. Aims. We report on the
discovery of the transiting planet CoRoT-Exo-2b, with a period of 1.743 days,
and characterize its main parameters. Methods. We filter the CoRoT raw light
curve of cosmic impacts, orbital residuals, and low frequency signals from the
star. The folded light curve of 78 transits is fitted to a model to obtain the
main parameters. Radial velocity data obtained with the SOPHIE, CORALIE and
HARPS spectro-graphs are combined to characterize the system. The 2.5 min
binned phase-folded light curve is affected by the effect of sucessive
occultations of stellar active regions by the planet, and the dispersion in the
out of transit part reaches a level of 1.09x10-4 in flux units. Results. We
derive a radius for the planet of 1.465+-0.029 R_Jup and a mass of 3.31+-0.16
M_Jup, corresponding to a density of 1.31+-0.04 g/cm^3. The large radius of
CoRoT-Exo-2b cannot be explained by current models of evolution of irradiated
planets.


title: Scattering theory for the Gross-Pitaevskii equation in three dimensions

abstract:
  We study global behavior of small solutions of the Gross-Pitaevskii equation
in three dimensions. We prove that disturbances from the constant equilibrium
with small, localized energy, disperse for large time, according to the
linearized equation. Translated to the defocusing nonlinear Schr\"odinger
equation, this implies asymptotic stability of all plane wave solutions for
such disturbances. We also prove that every linearized solution with finite
energy has a nonlinear solution which is asymptotic to it. The key ingredients
are: (1) some quadratic transforms of the solutions, which effectively
linearize the nonlinear energy space, (2) a bilinear Fourier multiplier
estimate, which allows irregular denominators due to a degenerate non-resonance
property of the quadratic interactions, and (3) geometric investigation of the
degeneracy in the Fourier space to minimize its influence.


title:
Transiting exoplanets from the CoRoT space mission III. The
  spectroscopic transit of CoRoT-Exo-2b with SOPHIE and HARPS

abstract:
  We report on the spectroscopic transit of the massive hot-Jupiter
CoRoT-Exo-2b observed with the high-precision spectrographs SOPHIE and HARPS.
By modeling the radial velocity anomaly occurring during the transit due to the
Rossiter-McLaughlin (RM) effect, we determine the sky-projected angle between
the stellar spin and the planetary orbital axis to be close to zero
lambda=7.2+-4.5 deg, and we secure the planetary nature of CoRoT-Exo-2b. We
discuss the influence of the stellar activity on the RM modeling. Spectral
analysis of the parent star from HARPS spectra are presented.


title:
Constraining primordial magnetic fields with CMB polarization
  experiments

abstract:
  We calculate the effect that a primordial homogeneous magnetic field, $\B_0$,
will have on the different CMB power spectra due to Faraday rotation.
Concentrating on the $TB$, $EB$ and $BB$ correlations, we forecast the ability
for future CMB polarization experiments to constrain $\B_0$. Our results depend
on how well the foregrounds can be subtracted from the CMB maps, but we find a
predicted error between $\sigma_{\B_0} = 4 \times 10^{-11}$Gauss (for the QUIET
experiment with foregrounds perfectly subtracted) and $3 \times 10^{-10}$Gauss
(with the Clover experiment with no foreground subtraction). These constraints
are two orders of magnitudes better than the present limits on $\B_0$.


title:
A complex structure on the set of quasiconformally extendible
  non-overlapping mappings into a Riemann surface

abstract:
  Let \Sigma be a compact Riemann surface with n distinguished points
p_1,...,p_n. We prove that the set of n-tuples (\phi_1,...,\phi_n) of univalent
mappings \phi_i from the open unit disc into \Sigma mapping 0 to p_i, with
non-overlapping images and quasiconformal extensions to a neighbourhood of the
closed unit disk, carries a natural complex Banach manifold structure. This
complex structure is locally modelled on the n-fold product of a two
complex-dimensional extension of the universal Teichmueller space. Our results
are motivated by Teichmueller theory and two-dimensional conformal field
theory.


title: Resolving the universe with multifractals

abstract:
  We present a new method for dealing with geometrical selection effects in
galaxy surveys while using a multifractal framework. The power of multifractal
analysis lies in its connection to higher order moments, in that it not only
probes clustering on different scales but also different densities. Therefore
any incompleteness issues must be correctly addressed before blindly applying
this technique to real survey data.


title: Invariant subspaces of subgraded Lie algebras of compact operators

abstract:
  We show that finitely subgraded Lie algebras of compact operators have
invariant subspaces when conditions of quasinilpotence are imposed on certain
components of the subgrading. This allows us to obtain some useful information
about the structure of such algebras. As an application, we prove a number of
results on the existence of invariant subspaces for algebraic structures of
compact operators. Along the way we obtain new criteria for the
triangularizability of a Lie algebra of compact operators.


title:
Robustness and Infrared Sensitivity of Various Observables in the
  Application of AdS/CFT to Heavy Ion Collisions

abstract:
  We investigate the robustness with respect to nonconformality of five
properties of strongly coupled plasmas that have been calculated in N=4
supersymmetric Yang-Mills (SYM) theory at nonzero temperature, motivated by the
goal of understanding phenomena in heavy ion collisions. (The properties are
the jet quenching parameter, the velocity dependence of screening, and the drag
and transverse and longitudinal momentum diffusion coefficients for a heavy
quark pulled through the plasma.) We use a toy model in which nonconformality
is introduced via a one-parameter deformation of the AdS black hole dual to the
hot N=4 SYM plasma. Upon introducing a degree of nonconformality comparable to
that seen in lattice calculations of QCD at temperatures a few times that of
the crossover to quark-gluon plasma, we find that the jet quenching parameter
is affected by the nonconformality by at most 30%, the screening length is
affected by at most 20%, but the drag and diffusion coefficients for a slowly
moving heavy quark can be modified by as much as 80%. However, four of the five
properties that we investigate become completely insensitive to the
nonconformality in the limit v -> 1. The exception is the jet quenching
parameter, which is "infrared sensitive" even at v=1, where it is defined. It
is the only high-velocity observable that we investigate which is sensitive to
properties of the medium at infrared energy scales proportional to T, namely
the scales where the quark-gluon plasma of QCD can be strongly coupled. The
other four quantities all probe only scales that are larger than T by a factor
that diverges as v -> 1, namely scales where the N=4 SYM plasma can be strongly
coupled but the quark-gluon plasma of QCD is not.


title:
Observations of the Naked-Eye GRB 080319B: Implications of Nature's
  Brightest Explosion

abstract:
  The first gamma-ray burst (GRB) confirmed to be bright enough to be seen with
the naked eye, GRB 080319B at redshift z = 0.937, allowed for exquisite
follow-up observations across the electromagnetic spectrum. We present our
detailed optical and infrared observations of the afterglow, consisting of over
5000 images starting 51 s after the GRB trigger, in concert with our own
analysis of the Swift data. The event is extreme not only in observed
properties but intrinsically: it was the most luminous event ever recorded at
optical and infrared wavelengths and had an exceedingly high
isotropic-equivalent energy release in gamma-rays. At early times, the
afterglow evolution is broadly consistent with being reverse-shock dominated,
but then is subsumed by a forward shock at around 1000 s. The overall spectral
energy distribution, spanning from ultraviolet through near-infrared
wavelengths, shows no evidence for a significant amount of dust extinction in
the host frame. The afterglow evolution, however, is highly chromatic: starting
at about 1000 s the index shifts blueward before shifting back to the red at
late times. In our deepest late-time observations, we find tentative evidence
for an optical jet break and a luminous supernova. Finally, we examine the
detectability of such events with current and future facilities and find that
such an event could be detected in gamma-rays by BAT out to z = 10.7 (8 sigma),
while the nominal EXIST sensitivity would allow detection to z ~ 32. At K band,
this source would have been easily detected with meter-class telescopes to z ~
17.


title:
Effective single-particle order-N scheme for the dynamics of open
  non-interacting many-body systems

abstract:
  Quantum master equations are common tools to describe the dynamics of
many-body systems open to an environment. Due to the interaction with the
latter, even for the case of non-interacting electrons, the computational cost
to solve these equations increases exponentially with the particle number. We
propose a simple scheme, that allows to study the dynamics of $N$
non-interacting electrons taking into account both dissipation effects and
Fermi statistics, with a computational cost that scales linearly with $N$. Our
method is based on a mapping of the many-body system to a specific set of
effective single-particle systems. We provide detailed numerical results
showing excellent agreement between the effective single-particle scheme and
the exact many-body one, as obtained from studying the dynamics of two
different systems. In the first, we study optically-induced currents in quantum
rings at zero temperature, and in the second we study a linear chain coupled at
its ends to two thermal baths with different (finite) temperatures. In
addition, we give an analytical justification for our method, based on an exact
averaging over the many-body states of the original master equations.


title:
Proplyds and Massive Disks in the Orion Nebula Cluster Imaged with CARMA
  and SMA

abstract:
  [Abridged] We imaged a 2' x 2' region of the Orion Nebula cluster in 1.3 mm
wavelength continuum emission with the recently commissioned Combined Array for
Research in Millimeter Astronomy (CARMA) and with the Submillimeter Array
(SMA). Our mosaics include >250 known near-IR cluster members, of which 36 are
so-called "proplyds" that have been imaged previously with the Hubble Space
Telescope. We detected 40 sources in 1 mm continuum emission, and several of
them are spatially resolved with our observations. Dust masses inferred for
detected sources range from 0.01 to 0.5 Msun, and the average disk mass for
undetected sources is estimated to be ~0.001 Msun, approximately an order of
magnitude smaller than the minimum mass solar nebula. Most stars in the ONC
thus do not appear to currently possess sufficient mass in small dust grains to
form Jupiter-mass (or larger) planets. Comparison with previous results for
younger and older regions indicates that massive disks evolve significantly on
~Myr timescales. We also show that the percentage of stars in Orion surrounded
by disks more massive than ~0.01 Msun is substantially lower than in Taurus,
indicating that environment has an impact on the disk mass distribution.
Finally, we explore potential correlations of disk mass with stellar mass and
location within the cluster.


title: M2 to D2

abstract:
  We examine the recently proposed "3-algebra" field theory for multiple
M2-branes and show that when a scalar field valued in the 3-algebra develops a
vacuum expectation value, the resulting Higgs mechanism has the novel effect of
promoting topological (Chern-Simons) to dynamical (Yang-Mills) gauge fields.
This leads to a precise derivation of the maximally supersymmetric Yang-Mills
theory on multiple D2-branes and thereby provides a relationship between
3-algebras and Yang-Mills theories. We discuss the physical interpretation of
this result.


title: Fundamental groups of symmetric sextics

abstract:
  We study the moduli spaces and compute the fundamental groups of plane
sextics of torus type with at least two type $\bold{E}_6$ singular points. As a
simple application, we compute the fundamental groups of 125 other sextics,
most of which are new.


title:
Anomalous Nernst effect from a chiral d-density wave state in underdoped
  cuprate superconductors

abstract:
  We show that the breakdown of time-reversal invariance, confirmed by the
recent polar Kerr effect measurements in the cuprates, implies the existence of
an anomalous Nernst effect in the pseudogap phase of underdoped cuprate
superconductors. Modeling the time-reversal-breaking ordered state by the
chiral d-density-wave state, we find that the magnitude of the Nernst effect
can be sizable even at temperatures much higher than the superconducting
transition temperature. These results imply that the experimentally found
Nernst effect at the pseudogap temperatures may be due to the chiral d-density
wave ordered state with broken time-reversal invariance.


title:
Improving Photometric Redshifts using GALEX Observations for the SDSS
  Stripe 82 and the Next Generation of SZ Cluster Surveys

abstract:
  Four large-area Sunyaev-Zeldovich (SZ) experiments -- APEX-SZ, SPT, ACT, and
Planck -- promise to detect clusters of galaxies through the distortion of
Cosmic Microwave Background photons by hot (> 10^6 K) cluster gas (the SZ
effect) over thousands of square degrees. A large observational follow-up
effort to obtain redshifts for these SZ-detected clusters is under way. Given
the large area covered by these surveys, most of the redshifts will be obtained
via the photometric redshift (photo-z) technique. Here we demonstrate, in an
application using ~3000 SDSS stripe 82 galaxies with r<20, how the addition of
GALEX photometry (FUV, NUV) greatly improves the photometric redshifts of
galaxies obtained with optical griz or ugriz photometry. In the case where
large spectroscopic training sets are available, empirical neural-network-based
techniques (e.g., ANNz) can yield a photo-z scatter of $\sigma_z = 0.018
(1+z)$. If large spectroscopic training sets are not available, the addition of
GALEX data makes possible the use simple maximum likelihood techniques, without
resorting to Bayesian priors, and obtains $\sigma_z=0.04(1+z)$, accuracy that
approaches the accuracy obtained using spectroscopic training of neural
networks on ugriz observations. This improvement is especially notable for blue
galaxies. To achieve these results, we have developed a new set of high
resolution spectral templates based on physical information about the star
formation history of galaxies. We envision these templates to be useful for the
next generation of photo-z applications. We make our spectral templates and new
photo-z catalogs available to the community at
http://www.ice.csic.es/personal/jimenez/PHOTOZ .


title: Characters of prime degree

abstract:
  Let $G$ be a finite nilpotent group, $\chi$ and $\psi$ be irreducible complex
characters of $G$ of prime degree. Assume that $\chi(1)=p$. Then either the
product $\chi\psi$ is a multiple of an irreducible character or $\chi\psi$ is
the linear combination of at least $\frac{p+1}{2}$ distinct irreducible
characters.


title: Cosmological constraints on unparticle dark matter

abstract:
  In unparticle dark matter (unmatter) models the equation of state of the
unmatter is given by $p=\rho/(2d_U+1)$, where $d_U$ is the scaling factor.
Unmatter with such equations of state would have a significant impact on the
expansion history of the universe. Using type Ia supernovae (SNIa), the baryon
acoustic oscillation (BAO) measurements and the shift parameter of the cosmic
microwave background (CMB) to place constraints on such unmatter models we find
that if only the SNIa data is used the constraints are weak. However, with the
BAO and CMB shift parameter data added strong constraints can be obtained. For
the $\Lambda$UDM model, in which unmatter is the sole dark matter, we find that
$d_U > 60$ at 95% C.L. For comparison, in most unparticle physics models it is
assumed $d_U<2$. For the $\Lambda$CUDM model, in which unmatter co-exists with
cold dark matter, we found that the unmatter can at most make up a few percent
of the total cosmic density if $d_U<10$, thus it can not be the major component
of dark matter.


title:
A Model-Based Frequency Constraint for Mining Associations from
  Transaction Data

abstract:
  Mining frequent itemsets is a popular method for finding associated items in
databases. For this method, support, the co-occurrence frequency of the items
which form an association, is used as the primary indicator of the
associations's significance. A single user-specified support threshold is used
to decided if associations should be further investigated. Support has some
known problems with rare items, favors shorter itemsets and sometimes produces
misleading associations.
  In this paper we develop a novel model-based frequency constraint as an
alternative to a single, user-specified minimum support. The constraint
utilizes knowledge of the process generating transaction data by applying a
simple stochastic mixture model (the NB model) which allows for transaction
data's typically highly skewed item frequency distribution. A user-specified
precision threshold is used together with the model to find local frequency
thresholds for groups of itemsets. Based on the constraint we develop the
notion of NB-frequent itemsets and adapt a mining algorithm to find all
NB-frequent itemsets in a database. In experiments with publicly available
transaction databases we show that the new constraint provides improvements
over a single minimum support threshold and that the precision threshold is
more robust and easier to set and interpret by the user.


title: Turbulent dynamics in rotating helium superfluids

abstract:
  New techniques, both for generating and detecting turbulence in the helium
superfluids 3He-B and 4He, have recently given insight in how turbulence is
started, what the dissipation mechanisms are, and how turbulence decays when it
appears as a transient state or when externally applied turbulent pumping is
switched off. Important simplifications are obtained by using 3He-B as working
fluid, where the highly viscous normal component is practically always in a
state of laminar flow, or by cooling 4He to low temperatures where the normal
fraction becomes vanishingly small. We describe recent studies from the low
temperature regime, where mutual friction becomes small or practically
vanishes. This allows us to elucidate the mechanisms at work in quantum
turbulence on approaching the zero temperature limit.


title: On the collision of two shock waves in AdS5

abstract:
  We consider two ultrarelativistic shock waves propagating and colliding in
five-dimensional Anti-de-Sitter spacetime. By transforming to Rosen
coordinates, we are able to find the form of the metric shortly after the
collision. Using holographic renormalization, we calculate the energy-momentum
tensor on the boundary of AdS space for early times after the collision. Via
the gauge-gravity duality, this gives some insights on bulk dynamics of systems
created by high energy scattering in strongly coupled gauge theories. We find
that Bjorken boost-invariance is explicitely violated at early times and we
obtain an estimate for the thermalization time in this simple system.


title: Is the silicate emission feature only influenced by grain size?

abstract:
  The flattening of the 10mu silicate emission feature observed in the spectra
of T Tauri and Herbig Ae/Be stars is usually interpreted as an indicator of
grain growth. We show in this paper that a similar behaviour of the feature
shape occurs when the porosity of composite grains varies. The fluffy
aggregates, having inclusions of different sizes, were modeled by multi-layered
spheres consisting of amorphous carbon, amorphous silicate and vacuum. It is
also found that the inclusion of crystalline silicates in composite porous
particles can lead to a shift of the known resonances and production of new
ones.


title:
Observation of pinning mode of stripe phases of 2D systems in high
  Landau levels

abstract:
  We study the radio-frequency diagonal conductivities of the anisotropic
stripe phases of higher Landau levels near half integer fillings. In the hard
direction, in which larger dc resistivity occurs, the spectrum exhibits a
striking resonance, while in the orthogonal, easy direction, no resonance is
discernable. The resonance is interpreted as a pinning mode of the stripe
phase.


title: Examination of Flavor Symmetry in $B, B_s \to K \pi$ Decays

abstract:
  We study a relation between the weak phase $\gamma$ and the rates and CP
asymmetries of several $K \pi$ decays of $B^+$, $B^0$, and $B_s$, emphasizing
the impact of the latter measurements. Current data indicate large SU(3)
breaking in the strong phases or failure of factorization (including its
application to penguin amplitudes) in $K \pi$ modes of $B^0$ and $B_s$. SU(3)
and factorization only remain approximately valid if the branching ratio for
$B_s \to K^- \pi^+$ exceeds its current value of $(5.27 \pm 1.17) \times
10^{-6}$ by at least 42%, or if a parameter $\xi$ describing ratios of form
factors and decay constants is shifted from its nominal value by more than
twice its estimated error.


title: A Type System for Data-Flow Integrity on Windows Vista

abstract:
  The Windows Vista operating system implements an interesting model of
multi-level integrity. We observe that in this model, trusted code can be
blamed for any information-flow attack; thus, it is possible to eliminate such
attacks by static analysis of trusted code. We formalize this model by
designing a type system that can efficiently enforce data-flow integrity on
Windows Vista. Typechecking guarantees that objects whose contents are
statically trusted never contain untrusted values, regardless of what untrusted
code runs in the environment. Some of Windows Vista's runtime access checks are
necessary for soundness; others are redundant and can be optimized away.


title: Archiving: The Overlooked Spreadsheet Risk

abstract:
  This paper maintains that archiving has been overlooked as a key spreadsheet
internal control. The case of failed Jamaican commercial banks demonstrates how
poor archiving can lead to weaknesses in spreadsheet control that contribute to
operational risk. In addition, the Sarbanes-0xley Act contains a number of
provisions that require tighter control over the archiving of spreadsheets. To
mitigate operational risks and achieve compliance with the records-related
provisions of Sarbanes-Oxley, the author argues that organisations should
introduce records management programmes that provide control over the archiving
of spreadsheets. At a minimum, spreadsheet archiving controls should identify
and ensure compliance with retention requirements, support document production
in the event of regulatory inquiries or litigation, and prevent unauthorised
destruction of records.


title: Codeword stabilized quantum codes: algorithm and structure

abstract:
  The codeword stabilized ("CWS") quantum codes formalism presents a unifying
approach to both additive and nonadditive quantum error-correcting codes
(arXiv:0708.1021). This formalism reduces the problem of constructing such
quantum codes to finding a binary classical code correcting an error pattern
induced by a graph state. Finding such a classical code can be very difficult.
Here, we consider an algorithm which maps the search for CWS codes to a problem
of identifying maximum cliques in a graph. While solving this problem is in
general very hard, we prove three structure theorems which reduce the search
space, specifying certain admissible and optimal ((n,K,d)) additive codes. In
particular, we find there does not exist any ((7,3,3)) CWS code though the
linear programming bound does not rule it out. The complexity of the CWS search
algorithm is compared with the contrasting method introduced by Aggarwal and
Calderbank (arXiv:cs/0610159).


title:
Quantal time asymmetry: mathematical foundation and physical
  interpretation

abstract:
  For a quantum theory that includes exponentially decaying states and
Breit-Wigner resonances, which are related to each other by the lifetime-width
relation $\tau=\frac{\hbar}{\Gamma}$, where $\tau$ is the lifetime of the
decaying state and $\Gamma$ the width of the resonance, one has to go beyond
the Hilbert space and beyond the Schwartz-Rigged Hilbert Space
$\Phi\subset\mathcal{H}\subset\Phi^\times$ of the Dirac formalism. One has to
distinguish between prepared states, using a space $\Phi_-\subset\mat hcal{H}$,
and detected observables, using a space $\Phi_+\subset\mathcal{H}$, where
$-(+)$ refers to analyticity of the energy wave function in the lower (upper)
complex energy semiplane.
  This differentiation is also justified by causality: A state needs to be
prepared first, before an observable can be measured in it. The axiom that will
lead to the lifetime-width relation is that $\Phi_+$ and $\Phi_-$ are Hardy
spaces of the upper and lower semiplane, respectively. Applying this axiom to
the relativistic case for the variable $\s=p_\mu p^\mu$ leads to semigroup
transformations into the forward light cone (Einstein causality) and a precise
definition of resonance mass and width.


title:
Comparing energy loss and $p_{\perp}$-broadening in perturbative QCD
  with strong coupling $\mathcal{N}=4$ SYM theory

abstract:
  We compare medium induced energy loss and $p_{\perp}$-broadening in
perturbative QCD with that of the trailing string picture of SYM theory. We
consider finite and infinite extent matter as well as relativistic heavy quarks
which correspond to those being produced in the medium or external to it. When
expressed in terms of the appropriate saturation momentum, we find identical
parametric forms for energy loss in perturbative QCD and SYM theory. We find
simple correspondences between $p_{\perp}$-broadening in QCD and in SYM theory
although $p_{\perp}$-broadening is radiation dominated in SYM theory and
multiple scattering dominated in perturbative QCD.


title:
Strongly Correlated Electrons in the $[Ni(hmp)(ROH)X]_4$ Single Molecule
  Magnet: A DFT+U Study

abstract:
  The single-molecule magnet $\mathrm{[Ni(hmp)(MeOH)Cl]_4}$ is studied using
both density functional theory (DFT) and the DFT+U method, and the results are
compared. By incorporating a Hubbard-U like term for both the nickel and oxygen
atoms, the experimentally determined ground state is successfully obtained, and
the exchange coupling constants derived from the DFT+U calculation agree with
experiment very well. The results show that the nickel 3d and oxygen 2p
electrons in this molecule are strongly correlated, and thus the inclusion of
on-site Coulomb energies is crucial to obtaining the correct results.


title:
Proximity of antiferromagnetism and superconductivity in
  LaO$_{1-x}$F$_x$FeAs: effective Hamiltonian from ab initio studies

abstract:
  We report density functional theory calculations for the parent compound
LaOFeAs of the newly discovered 26K Fe-based superconductor
LaO$_{1-x}$F$_x$FeAs. We find that the ground state is an ordered
antiferromagnet, with staggered moment about 2.3$\mu_B$, on the border with the
Mott insulating state. We fit the bands crossing the Fermi surface, derived
from Fe and As, to a tight-binding Hamiltonian using maximally localized
Wannier functions on Fe 3d and As 4p orbitals. The model Hamiltonian accurately
describes the Fermi surface obtained via first-principles calculations. Due to
the evident proximity of superconductivity to antiferromagnetism and the Mott
transition, we suggest that the system may be an analog of the electron doped
cuprates, where antiferromagnetism and superconductivity coexist.


title: Memory effects in quantum channel discrimination

abstract:
  We consider quantum-memory assisted protocols for discriminating quantum
channels. We show that for optimal discrimination of memory channels, memory
assisted protocols are needed. This leads to a new notion of distance for
channels with memory. For optimal discrimination and estimation of sets of
unitary channels memory-assisted protocols are not required.


title:
Quantum Monte Carlo Simulations of the BCS-BEC Crossover at Finite
  Temperature

abstract:
  The Quantum Monte Carlo method for spin 1/2 fermions at finite temperature is
formulated for dilute systems with an s-wave interaction. The motivation and
the formalism are discussed along with descriptions of the algorithm and
various numerical issues. We report on results for the energy, entropy and
chemical potential as a function of temperature. We give upper bounds on the
critical temperature T_c for the onset of superfluidity, obtained by studying
the finite size scaling of the condensate fraction. All of these quantities
were computed for couplings around the unitary regime in the range -0.5 \le
(k_F a)^{-1} \le 0.2, where a is the s-wave scattering length and k_F is the
Fermi momentum of a non-interacting gas at the same density. In all cases our
data is consistent with normal Fermi gas behavior above a characteristic
temperature T_0 > T_c, which depends on the coupling and is obtained by
studying the deviation of the caloric curve from that of a free Fermi gas. For
T_c < T < T_0 we find deviations from normal Fermi gas behavior that can be
attributed to pairing effects. Low temperature results for the energy and the
pairing gap are shown and compared with Green Function Monte Carlo results by
other groups.


title:
Theory of Bose-Einstein condensation and superfluidity of
  two-dimensional polaritons in an in-plane harmonic potential

abstract:
  Recent experiments have shown that it is possible to create an in-plane
harmonic potential trap for a two-dimensional (2D) gas of exciton-polaritons in
a microcavity structure, and evidence has been reported of Bose-Einstein
condensation of polaritons accumulated in this type of trap. We present here
the theory of Bose-Einstein condensation (BEC) and superfluidity of the exciton
polaritons in a harmonic potential trap. Along the way, we determine a general
method for defining the superfluid fraction in a 2D trap, in terms of angular
momentum representation. We show that in the continuum limit, as the trap
becomes shallower the superfluid fraction approaches the 2D Kosterlitz-Thouless
limit, while the condensate fraction approaches zero, as expected.


title:
Structure and stability of two-dimensional Bose-Einstein condensates
  under both harmonic and lattice confinement

abstract:
  In this work, we study pancake-shaped Bose-Einstein condensates confined by
both a cylindrically symmetric harmonic potential and an optical lattice with
equal periodicity in two orthogonal directions. We first identify the spectrum
of the underlying two-dimensional linear problem through multiple-scale
techniques. Then, we use the results obtained in the linear limit as a starting
point for a nonlinear existence and stability analysis of the lowest energy
states, emanating from the linear ones, in the nonlinear problem. Two-parameter
continuations of these states are performed for increasing nonlinearity and
optical lattice strengths, and their instabilities and temporal evolution are
investigated. It is found that the ground state as well as one of the excited
states are either stable or weakly unstable for both attractive and repulsive
interatomic interactions.


title: Trivializing a Family of Sasaki-Einstein Spaces

abstract:
  We construct an explicit diffeomorphism between the Sasaki-Einstein spaces
Y^{p,q} and the product space S^3 \times S^2 in the cases q \le 2. When q=1 we
express the K\"ahler quotient coordinates as an SU(2) bundle over S^2 which we
trivialize. When q=2 the quotient coordinates yield a non-trivial SO(3) bundle
over S^2 with characteristic class p, which is rotated to a bundle with
characteristic class 1 and re-expressed as Y^{2,1}, reducing the problem to the
case q=1. When q>2 the fiber is a lens space which is not a Lie group, and this
construction fails. We relate the S^2 \times S^3 coordinates to those for which
the Sasaki-Einstein metric is known. We check that the RR flux on the S^3 is
normalized in accordance with Gauss' law and use this normalization to
determine the homology classes represented by the calibrated cycles. As a
by-product of our discussion we find a diffeomorphism between T^{p,q} and
Y^{p,q} spaces, which means that T^{p,q} manifolds are also topologically S^3
\times S^2.


title: N = 8 Superconformal Chern--Simons Theories

abstract:
  A Lagrangian description of a maximally supersymmetric conformal field theory
in three dimensions was constructed recently by Bagger and Lambert (BL). The BL
theory has SO(4) gauge symmetry and contains scalar and spinor fields that
transform as 4-vectors. We verify that this theory has OSp(8|4) superconformal
symmetry and that it is parity conserving despite the fact that it contains a
Chern--Simons term. We describe several unsuccessful attempts to construct
theories of this type for other gauge groups and representations. This
experience leads us to conjecture the uniqueness of the BL theory. Given its
large symmetry, we expect this theory to play a significant role in the future
development of string theory and M-theory.


title: The preparation time in a scattering experiment

abstract:
  A quantum mechanical theory with time asymmetry intrinsic to states (or
observables) features the concept of an initial time of the state and thus a
preparation time of the physical system represented by the state. This special
time is investigated in the context of scattering theory, where, in standard
quantum mechanics, the physical meaning of a preparation time has remained
obscure. In an experiment, the preparation time corresponds to an ensemble of
times of scattering marking the times in the laboratory when one scattering
projectile interacts with one target quantum.


title: Equivariant K-theory, groupoids and proper actions

abstract:
  In this paper we define complex equivariant K-theory for actions of Lie
groupoids using finite-dimensional vector bundles. For a Bredon-compatible Lie
groupoid, this defines a periodic cohomology theory on the category of finite
equivariant CW-complexes. We also establish an analogue of the completion
theorem of Atiyah and Segal. Some examples are discussed.


title: Stoichiometric growth of high Curie temperature heavily-alloyed GaMnAs

abstract:
  Heavily-alloyed, 100 nm Ga1-xMnxAs (x>0.1) films are obtained via low
temperature molecular beam epitaxy utilizing a combinatorial technique which
allows systematic control of excess arsenic during growth. Reproducible,
optimized electronic, magnetic and structural properties are found in a narrow
range of stoichiometric growth conditions. The Curie temperature of
stoichiometric material is 150-165 K and independent of x within a large window
of growth conditions while substitutional Mn content increases linearly,
contradicting the prediction of the Zener Model of hole-mediated
ferromagnetism.


title: A secular theory of coplanar, non-resonant planetary system

abstract:
  We present the secular theory of coplanar $N$-planet system, in the absence
of mean motion resonances between the planets. This theory relies on the
averaging of a perturbation to the two-body problem over the mean longitudes.
We expand the perturbing Hamiltonian in Taylor series with respect to the
ratios of semi-major axes which are considered as small parameters, without
direct restrictions on the eccentricities. Next, we average out the resulting
series term by term. This is possible thanks to a particular but in fact quite
elementary choice of the integration variables. It makes it possible to avoid
Fourier expansions of the perturbing Hamiltonian. We derive high order
expansions of the averaged secular Hamiltonian (here, up to the order of 24)
with respect to the semi-major axes ratio. The resulting secular theory is a
generalization of the octupole theory. The analytical results are compared with
the results of numerical (i.e., practically exact) averaging. We estimate the
convergence radius of the derived expansions, and we propose a further
improvement of the algorithm. As a particular application of the method, we
consider the secular dynamics of three-planet coplanar system. We focus on
stationary solutions in the HD 37124 planetary system.


title:
Galaxy Zoo: The large-scale spin statistics of spiral galaxies in the
  Sloan Digital Sky Survey

abstract:
  We re-examine the evidence for a violation of large-scale statistical
isotropy in the distribution of projected spin vectors of spiral galaxies. We
have a sample of $\sim 37,000$ spiral galaxies from the Sloan Digital Sky
Survey, with their line of sight spin direction confidently classified by
members of the public through the online project Galaxy Zoo. After establishing
and correcting for a certain level of bias in our handedness results we find
the winding sense of the galaxies to be consistent with statistical isotropy.
In particular we find no significant dipole signal, and thus no evidence for
overall preferred handedness of the Universe. We compare this result to those
of other authors and conclude that these may also be affected and explained by
a bias effect.


title: Fermions tunnelling from the charged dilatonic black holes

abstract:
  Kerner and Mann's recent work shows that, for an uncharged and non-rotating
black hole, its Hawking temperature can be exactly derived by fermions
tunnelling from its horizons. In this paper, our main work is to improve the
analysis to deal with charged fermion tunnelling from the general dilatonic
black holes, specifically including the charged, spherically symmetric
dilatonic black hole, the rotating Einstein-Maxwell-Dilaton-Axion (EMDA) black
hole and the rotating Kaluza-Klein (KK) black hole. As a result, the correct
Hawking temperatures are well recovered by charged fermions tunnelling from
these black holes.


title:
SLE on doubly-connected domains and the winding of loop-erased random
  walks

abstract:
  Two-dimensional loop-erased random walks (LERWs) are random planar curves
whose scaling limit is known to be a Schramm-Loewner evolution SLE_k with
parameter k = 2. In this note, some properties of an SLE_k trace on
doubly-connected domains are studied and a connection to passive scalar
diffusion in a Burgers flow is emphasised. In particular, the endpoint
probability distribution and winding probabilities for SLE_2 on a cylinder,
starting from one boundary component and stopped when hitting the other, are
found. A relation of the result to conditioned one-dimensional Brownian motion
is pointed out. Moreover, this result permits to study the statistics of the
winding number for SLE_2 with fixed endpoints. A solution for the endpoint
distribution of SLE_4 on the cylinder is obtained and a relation to reflected
Brownian motion pointed out.


title:
Two characteristic energies in the low-energy antiferromagnetic response
  of the electron-doped high-temperature superconductor
  Nd$_{2-x}$Ce$_x$CuO$_{4+\delta}$

abstract:
  Inelastic neutron scattering for Nd$_{2-x}$Ce$_x$CuO$_{4+\delta}$ near
optimal doping ($x \approx 0.155$, $T_{c} = 25 \mathrm{K}$) reveals that the
dynamic magnetic susceptibility at the antiferromagnetic zone center exhibits
two characteristic energies in the superconducting state: $\omega_1 \approx 6.4
\mathrm{meV}$ and $\omega_2 \approx 4.5 \mathrm{meV}$. These two magnetic
energies agree $quantitatively$ with the $B_{1g}$ / $B_{2g}$ and $A_{1g}$
features previously observed in electronic Raman scattering, where the former
is believed to indicate the maximum electronic gap and the origin of the
smaller $A_{1g}$ feature has remained unexplained. The susceptibility change
upon cooling into the superconducting state is inconsistent with previous
claims of the existence of a magnetic resonance mode near 10 meV, but
consistent with a resonance at $\omega_2$.


title:
Stability of Quantized Vortices in a Bose-Einstein Condensate Confined
  in an Optical Lattice

abstract:
  We investigate the existence and especially the linear stability of single
and multiple-charge quantized vortex states of nonlinear Schroedinger equations
in the presence of a periodic and a parabolic potential in two spatial
dimensions. The study is motivated by the examination of pancake-shaped
Bose-Einstein condensates in the presence of magnetic and optical confiement. A
two-parameter space of the condensate's chemical potential versus the periodic
potential's strength is scanned for both single- and double-quantized vortex
states located at a local minimum or a local maximum of the lattice. Triply
charged vortices are also briefly discussed. Single-charged vortices are found
to be stable for cosinusoidal potentials and unstable for sinusoidal ones above
a critical strength. Higher charge vortices are more unstable for both types of
potentials and their dynamical evolution leads to breakup into single-charged
vortices.


title: On semi-infinite cohomology of finite dimensional graded algebras

abstract:
  We describe a general setting for the definition of semi-infinite cohomology
of finite dimensional algebras, and provide its categorical interpretation. We
apply this interpretation to compute semi-infinite cohomology of some modules
over the small group at a root of unity, generalizing an earlier result of S.
Arkhipov (conjectured by B. Feigin).


title:
Co-NMR Knight Shift of NaxCoO2 \dot yH2O Studied in Both Superconducting
  Regions of the Tc-nuQ3 Phase Diagram Divided by the Nonsuperconducting Phase

abstract:
  In the temperature (T)-nuQ3 phase diagram of NaxCoO2 \dot yH2O, there exist
two superconducting regions of nuQ3 separated by the nonsuperconducting region,
where nuQ3 is usually estimated from the peak position of the 59Co-NQR spectra
of the 5/2-7/2 transition and well-approximated here as nuQ3~3nuQ,nuQ being the
interaction energy between the nuclear quadrupole moment and the electric field
gradient. We have carried out measurements of the 59Co-NMR Knight shift (K) for
a single crystal in the higher-nuQ3 superconducting phase and found that K
begins to decrease with decreasing T at Tc for both magnetic field directions
parallel and perpendicular to CoO2-planes. The result indicates together with
the previous ones that the superconducting pairs are in the spin-singlet state
in both phases, excluding the possibility of the spin-triplet superconductivity
in this phase diagram. The superconductivity of this system spreads over the
wide nuQ3 regions, but is suppressed in the narrow region located at the middle
point of the region possibly due to charge instability.


title:
Isotope Effect on the Superconducting Transition Temperature of
  NaxCoO2.yH2O

abstract:
  The effect of the 16O-->18O substitution on the superconducting transition
temperatures Tc of NaxCoO2.yH2O has been studied for several sets of samples.
Each set has two kinds of samples, one with the oxygen sites in the CoO2 layers
filled with 16O atoms and another with these sites partially substituted with
18O isotope. These two kinds of samples were prepared in parallel in whole
preparation processes. For all the sample sets, we have not found any
significant difference of the Tc values between the non-substituted and
substituted samples, which indicates that the oxygen isotope effect is not
appreciable in NaxCoO2.yH2O. The result, however, does not necessarily exclude
the possibility of the phonon mechanism of the superconductivity, because the
strong correlation effect suppresses the isotope effect as pointed out
previously.


title: NMR studies of Successive Phase Transitions in Na0.5CoO2 and K0.5CoO2

abstract:
  59Co- and 23Na-NMR measurements have been carried out on polycrystalline and
c-axis aligned samples of Na0.5CoO2, which exhibits successive transitions at
temperatures T = 87 K (= Tc1) and T = 53 K (= Tc2). 59Co-NMR has also been
carried out on c-axis aligned crystallites of K0.5CoO2 with similar successive
transitions at Tc1 ~ 60 K and Tc2 ~ 20 K. For Na0.5CoO2, two sets of three NMR
lines of 23Na nuclei explained by considering the quadrupolar frequencies nuQ
~1.32 and 1.40 MHz have been observed above Tc1, as is expected from the
crystalline structure. Rather complicated but characteristic variation of the
23Na-NMR spectra has been observed with varying T through the transition
temperatures, and the internal fields at two crystallographically distinct Na
sites are discussed on the basis of the magnetic structures reported
previously. The internal fields at two distinct Co sites observed below Tc1 and
the 591/T1-T curves of Na0.5CoO2 and K0.5CoO2 are also discussed in a
comparative way.


title:
Search for W-prime boson resonances decaying to a top quark and a bottom
  quark

abstract:
  We search for the production of a heavy W-prime gauge boson that decays to
third generation quarks in 0.9 fb-1 of ppbar collisions at sqrt{s} = 1.96 TeV,
collected with the D0 detector at the Fermilab Tevatron collider. We find no
significant excess in the final-state invariant mass distribution and set upper
limits on the production cross section times branching fraction. For a
left-handed W-prime boson with SM couplings, we set a lower mass limit of 731
GeV. For right-handed W-prime bosons, we set lower mass limits of 739 GeV if
the W-prime boson decays to both leptons and quarks and 768 GeV if the W-prime
boson decays only to quarks. We also set limits on the coupling of the W-prime
boson to fermions as a function of its mass.


title:
Quasifermion spectrum at finite temperature from coupled Schwinger-Dyson
  equations for a fermion-boson system

abstract:
  We nonperturbatively investigate a fermion spectrum at finite temperature in
a chiral invariant linear sigma model. Coupled Schwinger-Dyson equations for
fermion and boson are developed in the real time formalism and solved
numerically. From the coupling of a massless fermion with a massive boson, the
fermion spectrum shows a three-peak structure at some temperatures even for the
strong coupling region. This means that the three-peak structure which was
originally found in the one-loop calculation is stable against higher order
corrections even in the strong coupling region.


title: Strong dineutron correlation in 8He and 18C

abstract:
  We study the spatial structure of four valence neutrons in the ground state
of $^8$He and $^{18}$C nuclei using a core+4$n$ model. For this purpose, we
employ a density-dependent contact interaction among the valence neutrons, and
solve the five-body Hamiltonian in the Hartree-Fock-Bogoliubov (HFB)
approximation. We show that two neutrons with the coupled spin of $S$=0 exhibit
a strong dineutron correlation around the surface of these nuclei, whereas the
correlation between the two dineutrons is much weaker. Our calculation
indicates that the probability of the (1p$_{3/2})^4$ and [(1p$_{3/2})^2$
(p$_{1/2})^2$] configurations in the ground state wave function of $^8$He
nucleus is 34.9% and 23.7%, respectively. This is consistent with the recent
experimental finding with the $^8$He($p,t)^6$He reaction, that is, the ground
state wave function of $^8$He deviates significantly from the pure
(1p$_{3/2})^4$ structure.


title:
Solving parallel transport equations in the higher-dimensional
  Kerr-NUT-(A)dS spacetimes

abstract:
  We obtain and study the equations describing the parallel transport of
orthonormal frames along geodesics in a spacetime admitting a non-degenerate
principal conformal Killing-Yano tensor h. We demonstrate that the operator F,
obtained by a projection of h to a subspace orthogonal to the velocity, has in
a generic case eigenspaces of dimension not greater than 2. Each of these
eigenspaces are independently parallel-propagated. This allows one to reduce
the parallel transport equations to a set of the first order ordinary
differential equations for the angles of rotation in the 2D eigenspaces.
General analysis is illustrated by studying the equations of the parallel
transport in the Kerr-NUT-(A)dS metrics. Examples of three, four, and five
dimensional Kerr-NUT-(A)dS are considered and it is shown that the obtained
first order equations can be solved by a separation of variables.


title: Rotational quasi periodicities and the Sun - heliosphere connection

abstract:
  Mutual quasi-periodicities near the solar-rotation period appear in time
series based on the Earth's magnetic field, the interplanetary magnetic field,
and signed solar-magnetic fields. Dominant among these is one at 27.03 +/- 0.02
days that has been highlighted by Neugebauer, et al. 2000, J. Geophys. Res.,
105, 2315. Extension of their study in time and to different data reveals
decadal epochs during which the ~ 27.0 day, a ~ 28.3 day, or other
quasi-periods dominate the signal. Space-time eigenvalue analyses of time
series in 30 solar latitude bands, based on synoptic maps of unsigned
photospheric fields, lead to two maximally independent modes that account for
almost 30% of the data variance. One mode spans 45 degrees of latitude in the
northern hemisphere and the other one in the southern. The modes rotate around
the Sun rigidly, not differentially, suggesting connection with the subsurface
dynamo. Spectral analyses yield familiar dominant quasi periods 27.04 +/- 0.03
days in the North and at 28.24 +/- 0.03 days in the South. These are replaced
during cycle 23 by one at 26.45 +/- 0.03 days in the North. The modes show no
tendency for preferred longitudes separated by ~ 180 degrees.


title:
Kinematic simulations of dynamo action with a hybrid
  boundary-element/finite-volume method

abstract:
  The experimental realization of dynamo excitation as well as theoretical and
numerical examinations of the induction equation have shown the relevance of
boundary conditions for a self-sustaining dynamo.
  Within the interior of a field producing domain geometric constraints or
varying material properties (e.g. electrical conductivity of the container
walls or localized high-permeability material) might also play a role.
Combining a grid based finite volume approach with the boundary element method
in a hybrid FV-BEM scheme offers the flexibility of a local discretization with
a stringent treatment of insulating magnetic boundary conditions in almost
arbitrary geometries at comparatively low costs. Kinematic simulations of
dynamo action generated by a well known prescribed mean flow demonstrate the
reliability of the approach.
  Future examinations are intended to understand the behavior of the VKS-dynamo
experiment where the field producing flow is driven by ferrous propellers and
the induction effects of conductivity/permeability inhomogeneities might
provide the required conditions for the measured dynamo characteristics.


title: QCD sum rules for rho mesons in vacuum and in-medium, re-examined

abstract:
  An updated investigation of QCD sum rules for the first two moments of rho
meson spectral functions, both in vacuum and in-medium, is performed with
emphasis on the role of the scale related to spontaneous chiral symmetry
breaking in QCD. It is demonstrated that these lowest moments of vector current
spectral distributions do permit an accurate sum rule analysis with controlled
input including QCD condensates of the lowest dimensions, whereas higher
moments are subject to uncertainties from higher dimensional condensates.
Possible connections with Brown-Rho scaling are discussed. The factorization
approximation for four-quark condensates is shown not to be applicable in any
of the cases studied.


title: Relative Cohen--Macaulayness of bigraded modules

abstract:
  In this paper we study the local cohomology of all finitely generated
bigraded modules over a standard bigraded polynomial ring which have only one
nonvanishing local cohomology with respect to one of the irrelevant bigraded
ideals.


title: Spectral Properties of Acoustic Gravity Wave Turbulence

abstract:
  The nonlinear turbulent interactions between acoustic gravity waves are
investigated using two dimensional nonlinear fluid simulations. The acoustic
gravity waves consist of velocity and density perturbations and propagate
across the density gradients in the vertical direction in the Earth's
atmosphere. We find that the coupled two component model exhibits generation of
large scale velocity potential flows along the vertical direction, while the
density perturbations relax towards an isotropic random distribution. The
characteristic turbulent spectrum associated with the system has a
Kolmogorov-like feature and tends to relax towards a $k^{-5/3}$ spectrum, where
$k$ is a typical wavenumber. The cross field diffusion associated with the
velocity potential grows linearly and saturates in the nonlinear phase.


title: Theory and Simulations of Whistler Wave Propagation

abstract:
  A linear theory of whistler wave is developed wihtin the paradigm of a two
dimensional incompressible electron magnetohydrodynamics model. Exact analytic
wave solutions are obtained for a small amplitude whistler wave that exhibit
magnetic field topological structures consistent with the observations and our
simulations in linear regime. In agreement with experiment, we find that the
parallel group velocity of the wave is large compared to its perpendicular
counterpart. Numerical simulations of collisional interactions demonstrate that
the wave magnetic field either coalesces or repels depending upon the polarity
of the associated current. In the nonlinear regime, our simulations demonstrate
that the evolution of wave magnetic field is governed essentially by the
nonlinear Hall force.


title:
The Slow X-Ray Expansion of the Northwestern Rim of the Supernova
  Remnant RX J0852.0-4622

abstract:
  The detection of radioactive decay line of 44Ti provides a unique evidence
that the gamma-ray source is a young (< 1,000 yr) supernova remnant because of
its short lifetime of about 90 yr. Only two Galactic remnants, Cassiopeia A and
RX J0852.0-4622, are hitherto reported to be the 44Ti line emitter, although
the detection from the latter has been debated. Here we report on an expansion
measurement of the northwestern rim of RX J0852.0-4622 obtained with X-ray
observations separated by 6.5 yr. The expansion rate is derived to be
0.023+/-0.006% that is about five times lower than those of young historical
remnants. Such a slow expansion suggests that RX J0852.0-4622 is not a young
remnant as has been expected. We estimate the age of 1,700-4,300 yr of this
remnant depending on its evolutionary stage. Assuming a high shock speed of
about 3000 km/sec, which is suggested by the detection of non-thermal X-ray
radiation, the distance of about 750 pc to this remnant is also derived.


title:
Efficient simulation of quantum evolution using dynamical
  coarse-graining

abstract:
  A novel scheme to simulate the evolution of a restricted set of observables
of a quantum system is proposed. The set comprises the spectrum-generating
algebra of the Hamiltonian. The idea is to consider a certain open-system
evolution, which can be interpreted as a process of weak measurement of the
distinguished observables performed on the evolving system of interest. Given
that the observables are "classical" and the Hamiltonian is moderately
nonlinear, the open system dynamics displays a large time-scales separation
between the dephasing of the observables and the decoherence of the evolving
state in the basis of the generalized coherent states (GCS), associated with
the spectrum-generating algebra. The time scale separation allows the unitary
dynamics of the observables to be efficiently simulated by the open-system
dynamics on the intermediate time-scale.The simulation employs unraveling of
the corresponding master equations into pure state evolutions, governed by the
stochastic nonlinear Schroedinger equantion (sNLSE). It is proved that GCS are
globally stable solutions of the sNLSE, if the Hamilonian is linear in the
algebra elements.


title:
Les quartiers de la lune de Troie ou le bouclier d'Achille, essai sur le
  corps de classe

abstract:
  This is a text in french about classical class field theory, readable with a
minimum of prerequisites


title: Properties of the periodic Hartree-Fock minimizer

abstract:
  We study the periodic Hartree-Fock model used for the description of
electrons in a crystal. The existence of a minimizer was previously shown by
Catto, Le Bris and Lions (Ann. Inst. H. Poincare Anal. Non Lineaire} 18 (2001),
no.6, 687--760). We prove in this paper that any minimizer is necessarily a
projector and that it solves a certain nonlinear equation, similarly to the
atomic case. In particular we show that the Fermi level is either empty or
totally filled.


title: Remarks on modular symbols for Maass wave forms

abstract:
  In this paper I introduce modular symbols for Maass wave cusp forms. They
appear in the guise of finitely additive functions on the Boolean algebra
generated by intervals with non--positive rational ends, with values in
analytic functions (pseudo--measures in the sense of [MaMar2]). After
explaining the basic issues and analogies in the extended Introduction, I
construct modular symbols in the sec. 1 and the related L\'evy--Mellin
transforms in the sec. 2. The whole paper is an extended footnote to the
Lewis--Zagier fundamental study [LZ2].


title:
Spectral fluctuations of billiards with mixed dynamics: from time series
  to superstatistics

abstract:
  A statistical analysis of the eigenfrequencies of two sets of superconducting
microwave billiards, one with mushroom-like shape and the other from the
familiy of the Limacon billiards, is presented. These billiards have mixed
regular-chaotic dynamics but different structures in their classical phase
spaces. The spectrum of each billiard is represented as a time series where the
level order plays the role of time. Two most important findings follow from the
time-series analysis. First, the spectra can be characterized by two distinct
relaxation lengths. This is a prerequisite for the validity of the
superstatistical approach which is based on the folding of two distribution
functions. Second, the shape of the resulting probability density function of
the so-called superstatistical parameter is reasonably approximated by an
inverse chi-square distribution. This distribution is used to compute
nearest-neighbor spacing distributions and compare them with those of the
resonance frequencies of billiards with mixed dynamics within the framework of
superstatistics. The obtained spacing distribution is found to present a good
description of the experimental ones and is of the same or even better quality
as a number of other spacing distributions, including the one from Berry and
Robnik. However, in contrast to other approaches towards a theoretical
description of spectral properties of systems with mixed dynamics,
superstatistics also provides a description of properties of the
eigenfunctions. Indeed, the inverse chi-square parameter distribution is found
suitable for the analysis of experimental resonance strengths in the Limacon
billiards within the framework of superstatistics.


title: Emergent Spacetime and The Cosmological Constant

abstract:
  We address issues on the origin of gravity and the dark energy (or the
cosmological constant) from the perspectives of emergent gravity. We discuss
how the emergent gravity reveals a noble, radically different picture about the
origin of spacetime, which is crucial for a tenable solution of the
cosmological constant problem. In particular, the emergent gravity naturally
explains the dynamical origin of flat spacetime, which is absent in Einstein
gravity.


title: Bimonotone enumeration

abstract:
  Solutions of a diophantine equation $f(a,b) = g(c,d)$, with $a,b,c,d$ in some
finite range, can be efficiently enumerated by sorting the values of $f$ and
$g$ in ascending order and searching for collisions. This article considers
functions that are bimonotone in the sense that $f(a,b) \le f(a',b')$ whenever
$a \le a'$ and $b \le b'$. A two-variable polynomial with non-negative
coefficients is a typical example. The problem is to efficiently enumerate all
pairs $(a,b)$ such that the values $f(a,b)$ appear in increasing order. We
present an algorithm that is memory-efficient and highly parallelizable. In
order to enumerate the first $n$ values of $f$, the algorithm only builds up a
priority queue of length at most $\sqrt{2n}+1$. In terms of bit-complexity this
ensures that the algorithm takes time $O(n \log^2 n)$ and requires memory
$O(\sqrt{n} \log n)$, which considerably improves on the memory bound $\Theta(n
\log n)$ provided by a naive approach, and extends the semimonotone enumeration
algorithm previously considered by R.L. Ekl and D.J. Bernstein.


title: Topological quantization of ensemble averages

abstract:
  We define the current of a quantum observable and, under well defined
conditions, we connect its ensemble average to the index of a Fredholm
operator. The present work builds on a formalism developed by Kellendonk and
Schulz-Baldes \cite{Kellendonk:2004p597} to study the quantization of edge
currents for continuous magnetic Schroedinger operators. The generalization
given here may be a useful tool to scientists looking for novel manifestations
of the topological quantization. As a new application, we show that the
differential conductance of atomic wires is given by the index of a certain
operator. We also comment on how the formalism can be used to probe the
existence of edge states.

categories: cond-mat.mes-hall cond-mat.stat-mech hep-th math-ph math.MP


title: $\eta/s$ and Phase Transitions

abstract:
  We present a calculation of eta/s for the meson gas (zero baryon number),
with the viscosity computed within unitarized NLO chiral perturbation theory,
and confirm the observation that eta/s decreases towards the possible phase
transition to a quark-gluon plasma/liquid. The value is somewhat higher than
previously estimated in LO chi PT. We also examine the case of atomic Argon gas
to check the discontinuity of eta/s across a first order phase transition. Our
results suggest employing this dimensionless number, sometimes called KSS
number (in analogy with other ratios in fluid mechanics such as Reynolds number
or Prandtl number) to pin down the phase transition and critical end point to a
cross-over in strongly interacting nuclear matter between the hadron gas and
quark and gluon plasma/liquid.


title: Lorentz Transformation and General Covariance Principle

abstract:
  I tell about different mathematical tool that is important in general
relativity. The text of the book includes definition of geometrical object,
concept of reference frame, geometry of metric-affinne manifold. Using this
concept I learn few physical applications: dynamics and Lorentz transformation
in gravitational fields, Doppler shift.
  A reference frame in event space is a smooth field of orthonormal bases.
Every reference frame is equipped by anholonomic coordinates. Using anholonomic
coordinates allows to find out relative speed of two observers and appropriate
Lorentz transformation. Synchronization of a reference frame is an anholonomic
time coordinate. Simple calculations show how synchronization influences time
measurement in the vicinity of the Earth. Measurement of Doppler shift from the
star orbiting the black hole helps to determine mass of the black hole.
  We call a manifold with torsion and nonmetricity the metric\hyph affine
manifold. The nonmetricity leads to a difference between the auto parallel line
and the extreme line, and to a change in the expression of the Frenet transport
and moving basis. The torsion leads to a change in the Killing equation. We
also need to add a similar equation for the connection.
  The analysis of the Frenet transport leads to the concept of the Cartan
transport and an introduction of the connection compatible with the metric
tensor. The dynamics of a particle follows to the Cartan transport. We need
additional physical constraints to make a nonmetricity observable. Learning how
torsion influences on tidal force reveals similarity between tidal equation for
geodesic and the Killing equation of second type.


title: Virial theorems for trapped cold atoms

abstract:
  We present a general virial theorem for quantum particles with arbitrary
zero-range or finite-range interactions in an arbitrary external potential. We
deduce virial theorems for several situations relevant to trapped cold atoms:
zero-range interactions with and without Efimov effect, hard spheres, narrow
Feshbach resonances, and finite-range interactions. If the scattering length
$a$ is varied adiabatically in the BEC-BCS crossover, we find that the trapping
potential energy as a function of $1/a$ has an inflexion point at unitarity.


title:
Will the recently approved LARES mission be able to measure the
  Lense-Thirring effect at 1%?

abstract:
  After the approval by the Italian Space Agency of the LARES satellite, which
should be launched at the end of 2009 with a VEGA rocket and whose claimed goal
is a about 1% measurement of the general relativistic gravitomagnetic
Lense-Thirring effect in the gravitational field of the spinning Earth, it is
of the utmost importance to reliably assess the total realistic accuracy that
can be reached by such a mission. The observable is a linear combination of the
nodes of the existing LAGEOS and LAGEOS II satellites and of LARES able to
cancel out the impact of the first two even zonal harmonic coefficients of the
multipolar expansion of the classical part of the terrestrial gravitational
potential representing a major source of systematic error. While LAGEOS and
LAGEOS II fly at altitudes of about 6000 km, LARES will be placed at an
altitude of 1450 km. Thus, it will be sensitive to much more even zonals than
LAGEOS and LAGEOS II. Their corrupting impact \delta\mu has been evaluated by
using the standard Kaula's approach up to degree L=70 along with the sigmas of
the covariance matrices of eight different global gravity solutions
(EIGEN-GRACE02S, EIGEN-CG03C, GGM02S, GGM03S, JEM01-RL03B, ITG-Grace02s,
ITG-Grace03, EGM2008) obtained by five institutions (GFZ, CSR, JPL, IGG, NGA)
with different techniques from long data sets of the dedicated GRACE mission.
It turns out \delta\mu about 100-1000% of the Lense-Thirring effect. An
improvement of 2-3 orders of magnitude in the determination of the high degree
even zonals would be required to constrain the bias to about 1-10%.

categories: gr-qc astro-ph physics.geo-ph physics.space-ph


title:
Comment on "A neoclassical calculation of rotation profiles and
  comparison with DIII-D measurements"

abstract:
  The calculation presented in "A neoclassical calculation of rotation profiles
and comparison with DIII-D measurements" by Stacey, Johnson, and Mandrekas,
[Physics of Plasmas, 13, (2006)], contains several errors, including the
neglect of the toroidal electric field, an unphysical expression for the
electrostatic potential, and an unevaluated relation among its parameters. An
alternative formulation is discussed.


title: Post-radiation evolution of black holes

abstract:
  The expectation-value equations for the collapse of a macroscopic,
spherically symmetric, and uncharged body are integrated up to the limit of
validity of semiclassical theory. The collapse finishes with a true stable
black hole of the mass microscopically exceeding the vacuum-induced charge. The
apparent horizon is almost closed. The most important feature of the solution
is the presence of an irremovable Cauchy horizon.


title:
On the electrostatic field of a tokamak in the limit of large aspect
  ratio and concentric circular flux surfaces

abstract:
  From a common expression for the poloidal electrostatic field of a tokamak,
in the limit of large aspect ratio and concentric circular flux surfaces, one
may determine the associated potential. This potential satisfies Poisson's
equation, which reduces to Laplace's equation when the medium has vanishing
charge density, in axial geometry but not toroidal geometry. A simple
transformation takes the potential over to the correct harmonic form for
tokamak coordinates, and the resulting electrostatic field is calculated. From
the radial field one may estimate the supporting charge density on the
boundary, and from the poloidal field one may determine a prediction for the
radial dependence of the electron temperature, which does not compare well with
a rough estimate of the profile often seen in a tokamak.


title: Pure spin photocurrents

abstract:
  The pure spin currents, i.e., the counterflow of particles with opposite spin
orientations, can be optically injected in semiconductors. Here, we develop a
phenomenological theory, which describes the polarization dependencies of spin
currents excited by linearly polarized light in bulk semiconductors and quantum
well structures of various symmetries. We present microscopic descriptions of
the pure spin photocurrents for interband optical transitions in undoped
quantum wells as well as for direct intersubband and indirect intrasubband
(Drude-like) transitions in n-doped quantum well structures. We also
demonstrate that pure spin currents can be generated in structures of
sufficiently low symmetries by simple electron gas heating. The theoretical
results are compared with recent experimental observations.


title: On "the plasma approximation"

abstract:
  ``The plasma approximation'' is, in the words of Pauli, ``not even wrong,''
as it expresses a disbelief in the symmetries of the underlying gauge field
theory. The electrostatic field in question is divergenceful yet has no sources
or sinks, thus breaking Lorentz covariance explicitly, and has no place in a
self-consistent theory. Utilizing it leads to inconsistencies in the equation
of motion and prevents a proper, field-theoretic treatment of condensed matter
in the plasma state. By exposing the fallacy of replacing one of the field
equations with one of the Bianchi identities, the applicability of Gauss' law
to plasma physics is assured.


title:
Recurrence and transience of a multi-excited random walk on a regular
  tree

abstract:
  We study a model of multi-excited random walk on a regular tree which
generalizes the models of the once excited random walk and the digging random
walk introduced by Volkov (2003). We show the existence of a phase transition
of the recurrence/transience property of the walk. In particular, we prove that
the asymptotic behavior of the walk depends on the order of the excitations,
which contrasts with the one dimensional setting studied by Zerner (2005). We
also consider the limiting speed of the walk in the transient regime and
conjecture that it is not a monotonic function of the environment.


title: Branching Process approach for 2-SAT thresholds

abstract:
  It is well known that, as $n$ tends to infinity, the probability of
satisfiability for a random 2-SAT formula on $n$ variables, where each clause
occurs independently with probability $\alpha/2n$, exhibits a sharp threshold
at $\alpha=1$. We study a more general 2-SAT model in which each clause occurs
independently but with probability $\alpha_i/2n$ where $i \in \{0,1,2\}$ is the
number of positive literals in that clause. We generalize branching process
arguments by Verhoeven(99) to determine the satisfiability threshold for this
model in terms of the maximum eigenvalue of the branching matrix.


title:
Iron-based layered superconductor LaO$_{1-x}$F$_x$FeAs: an
  antiferromagnetic semimetal

abstract:
  We have studied the newly found superconductor compound LaO$_{1-x}$F$_x$FeAs
through the first-principles density functional theory calculations. We find
that the parent compound LaOFeAs is a quasi-2-dimensional antiferromgnetic
semimetal with most carriers being electrons and with a magnetic moment of
$2.3\mu_B$ located around each Fe atom on the Fe-Fe square lattice. Furthermore
this is a commensurate antiferromagnetic spin density wave due to the Fermi
surface nesting, which is robust against the F-doping. The observed
superconduction happens on the Fe-Fe antiferromagnetic layer, suggesting a new
superconductivity mechanism, mediated by the spin fluctuations. An abrupt
change on the Hall measurement is further predicted for the parent compound
LaOFeAs.


title: Quantum communication on closed time-like curves

abstract:
  We define a new quantity we call a ctcbit that provides a means for
quantifying a qubit on a closed time-like curve (CTC) as a shared resource. We
describe a simple protocol for the sharing of information that is similar to
quantum teleportation but does not require an entangled particle pair or ebit.
While there is the appearance that the given resource is free, we employ a
non-Hausdorff topology to prevent any limitless information exchanges.
Nonetheless, the resource does limit the type of information that may be
transferred, though this limitation can be reduced through the use of weak
measurements. While the reality of CTCs is highly speculative, the present
paper provides a manner by which quantum informational methods may be employed
to study such problems and may ultimately prove useful in studying quantum
gravity.


title:
Discrete spectrum in a critical coupling case of Jacobi matrices with
  spectral phase transitions by uniform asymptotic analysis

abstract:
  For a two-parameter family of Jacobi matrices exhibiting first-order spectral
phase transitions, we prove discreteness of the spectrum in the positive real
axis when the parameters are in one of the transition boundaries. To this end
we develop a method for obtaining uniform asymptotics, with respect to the
spectral parameter, of the generalized eigenvectors. Our technique can be
applied to a wide range of Jacobi matrices.


title: Teleportation seen from space-time

abstract:
  Formal similarity between Minkowski tetrads and Bell bases allows to think of
metric tensors in terms of quantum teleportation protocols. The role of null
tetrads for quantum information processing is different. They define qubits
resistant to a special kind of noise that occurs if coding and decoding of
quantum information is performed in different reference frames. These examples
show that mutual links between quantum information and the 2-spinor calculus
may be nontrivial and worthy of further studies.


title: Dimension quotients

abstract:
  We present two approaches, one homological and the other simplicial, for the
investigation of dimension quotients of groups. The theory is illustrated, in
particular, with a conceptual discussion of the fourth and fifth dimension
quotients.


title: Comparing Classes of Finite Structures

abstract:
  We introduce a reducibility on classes of structures, essentially a uniform
enumeration reducibility. This reducibility is inspired by the Friedman-Stanley
paper on using Borel reductions to compare classes of countable structures.
  This reducibility is calibrated by comparing several classes of structures.
The class of cyclic graphs and the class of finite prime fields are equivalent,
and are properly below the class of arbitrary finite graphs. The class of
finite graphs and the class of finite linear orders are maximal among all
classes of finite structures.
  We also prove some general characterizations of reducibility to certain
classes. Examples of large chains and antichains of classes are constructed.


title: How to Distinguish Dark Energy and Modified Gravity?

abstract:
  The current accelerated expansion of our universe could be due to an unknown
energy component (dark energy) or a modification to general relativity
(modified gravity). In the literature, it has been proposed that combining the
probes of the cosmic expansion history and growth history can distinguish
between dark energy and modified gravity. In this work, without invoking
non-trivial dark energy clustering, we show that the possible interaction
between dark energy and dark matter could make the interacting dark energy
model and the modified gravity model indistinguishable. An explicit example is
also given. Therefore, it is required to seek some complementary probes beyond
the ones of cosmic expansion history and growth history.


title: Classification from a Computable Viewpoint

abstract:
  Classification is an important goal in many branches of mathematics. The idea
is to describe the members of some class of mathematical objects, up to
isomorphism or other important equivalence in terms of relatively simple
invariants. Where this is impossible, it is useful to have concrete results
saying so. In model theory and descriptive set theory, there is a large body of
work, showing that certain classes of mathematical structures admit
classification, while others do not. In the present paper, we describe some
recent work on classification in computable structure theory.


title: Index Sets of Computable Structures

abstract:
  The \emph{index set} of a computable structure $\mathcal{A}$ is the set of
indices for computable copies of $\mathcal{A}$. We determine the complexity of
the index sets of various mathematically interesting structures, including
arbitrary finite structures, $\mathbb{Q}$-vector spaces, Archimedean real
closed ordered fields, reduced Abelian $p$-groups of length less than
$\omega^{2}$, and models of the original Ehrenfeucht theory. The index sets for
these structures all turn out to be $m$-complete $\Pi_{n}^{0}$,
$d$-$\Sigma_{n}^{0}$, or $\Sigma_{n}^{0}$, for various $n$. In each case, the
calculation involves finding an \textquotedblleft optimal\textquotedblright% \
sentence (i.e., one of simplest form) that describes the structure. The form of
the sentence (computable $\Pi_{n}$, $d$-$\Sigma_{n}$, or $\Sigma_{n}$) yields a
bound on the complexity of the index set. When we show $m$% -completeness of
the index set, we know that the sentence is optimal. For some structures, the
first sentence that comes to mind is not optimal, and another sentence of
simpler form is shown to serve the purpose. For some of the groups, this
involves Ramsey theory.


title: Building an AdS/CFT superconductor

abstract:
  We show that a simple gravitational theory can provide a holographically dual
description of a superconductor. There is a critical temperature, below which a
charged condensate forms via a second order phase transition and the (DC)
conductivity becomes infinite. The frequency dependent conductivity develops a
gap determined by the condensate. We find evidence that the condensate consists
of pairs of quasiparticles.


title: Structures in Familiar Classes Which Have Scott Rank $\omega_1^{CK}$

abstract:
  There are familiar examples of computable structures having various
computable Scott ranks. There are also familiar structures, such as the
Harrison ordering, which have Scott rank $\omega_1^{CK}+1$. Makkai produced a
structure of Scott rank $\omega_1^{CK}$, which can be made computable, and
simplified so that it is just a tree. In the present paper, we show that there
are further computable structures of Scott rank $\omega_1^{CK}$ in the
following classes: undirected graphs, fields of any characteristic, and linear
orderings. The new examples share with the Harrison ordering, and the tree just
mentioned, a strong approximability property.


title:
Trapping of two-component matter-wave solitons by mismatched optical
  lattices

abstract:
  We consider a one-dimensional model of a two-component Bose-Einstein
condensate in the presence of periodic external potentials of opposite signs,
acting on the two species. The interaction between the species is attractive,
while intra-species interactions may be attractive too [the system of the
right-bright (BB) type], or of opposite signs in the two components [the
gap-bright (GB) model]. We identify the existence and stability domains for
soliton complexes of the BB and GB types. The evolution of unstable solitons
leads to the establishment of oscillatory states. The increase of the strength
of the nonlinear attraction between the species results in symbiotic
stabilization of the complexes, despite the fact that one component is centered
around a local maximum of the respective periodic potential.


title: $L_{p,q}$-Cohomology of Warped Cylinders

abstract:
  We extend some results by Gol'dshtein, Kuz'minov, and Shvedov about the
$L_p$-cohomology of warped cylinders to $L_{p,q}$-cohomology for different $p$
and $q$. As an application, we establish some sufficient conditions for the
nontriviality of the $L_{p,q}$-torsion of a surface of revolution in terms of
some Hardy constants.


title: Tidal torques. A critical review of some techniques

abstract:
  We point out that the MacDonald formula for body-tide torques is valid only
in the zeroth order of e/Q, while its time-average is valid in the first order.
So the formula cannot be used for analysis in higher orders of e/Q. This
necessitates corrections in the theory of tidal despinning and libration
damping.
  We prove that when the inclination is low and phase lags are linear in
frequency, the Kaula series is equivalent to a corrected version of the
MacDonald method. The correction to MacDonald's approach would be to set the
phase lag of the integral bulge proportional to the instantaneous frequency.
The equivalence of descriptions gets violated by a nonlinear
frequency-dependence of the lag.
  We explain that both the MacDonald- and Darwin-torque-based derivations of
the popular formula for the tidal despinning rate are limited to low
inclinations and to the phase lags being linear in frequency. The
Darwin-torque-based derivation, though, is general enough to accommodate both a
finite inclination and the actual rheology.
  Although rheologies with Q scaling as the frequency to a positive power make
the torque diverge at a zero frequency, this reveals not the impossible nature
of the rheology, but a flaw in mathematics, i.e., a common misassumption that
damping merely provides lags to the terms of the Fourier series for the tidal
potential. A hydrodynamical treatment (Darwin 1879) had demonstrated that the
magnitudes of the terms, too, get changed. Reinstating of this detail tames the
infinities and rehabilitates the "impossible" scaling law (which happens to be
the actual law the terrestrial planets obey at low frequencies).

categories: astro-ph physics.class-ph physics.geo-ph physics.hist-ph


title: Are Particles Self-Organized Systems?

abstract:
  Elementary particles possess quantized values of charge and internal angular
momentum or spin. These characteristics do not change when the particles
interact with other particles or fields as long as they preserve their
entities. Quantum theory does not explain this quantization. It is introduced
into the theory a priori. An interacting particle is an open system and thus
does not obey conservation laws. However, an open system may create dynamically
stable states with unchanged dynamical variables via self-organization. In
self-organized systems stability is achieved through the interplay of
nonlinearity and dissipation. Can self-organization be responsible for particle
formation? In this paper we develop and analyze a particle model based on
qualitative dynamics and the Feigenbaum universality. This model demonstrates
that elementary particles can be described as self-organized dynamical systems
belonging to a wide class of systems characterized by a hierarchy of
period-doubling bifurcations. This semi-qualitative heuristic model gives
possible explanations for charge and action quantization, and the origination
and interrelation between the strong, weak, and electromagnetic forces, as well
as SU(2) symmetry. It also provides a basis for particle taxonomy endorsed by
the Standard Model. The key result is the discovery that the Planck constant is
intimately related to elementary charge.


title: Factorial threefold hypersurfaces

abstract:
  Let $X$ be a hypersurface in $\mathbb{P}^{4}$ of degree $d$ that has at most
isolated ordinary double points. We prove that $X$ is factorial in the case
when $X$ has at most $(d-1)^{2}-1$ singular points.


title: Instantons beyond topological theory II

abstract:
  The present paper is the second part of our project in which we describe
quantum field theories with instantons in a novel way by using the "infinite
radius limit" (rather than the limit of free field theory) as the starting
point. The theory dramatically simplifies in this limit, because the
correlation functions of all, not only topological (or BPS), observables may be
computed explicitly in terms of integrals over finite-dimensional moduli spaces
of instanton configurations. In Part I (arXiv:hep-th/0610149) we discussed in
detail the one-dimensional (that is, quantum mechanical) models of this type.
Here we analyze the supersymmetric two-dimensional sigma models and
four-dimensional Yang--Mills theory, using the one-dimensional models as a
prototype. We go beyond the topological (or BPS) sectors of these models and
consider them as full-fledged quantum field theories. We study in detail the
space of states and find that the Hamiltonian is not diagonalizable, but has
Jordan blocks. This leads to the appearance of logarithms in the correlation
functions. We find that our theories are in fact logarithmic conformal field
theories (theories of this type are of interest in condensed matter physics).
We define jet-evaluation observables and consider in detail their correlation
functions. They are given by integrals over the moduli spaces of holomorphic
maps, which generalize the Gromov--Witten invariants. These integrals generally
diverge and require regularization, leading to an intricate logarithmic mixing
of the operators of the sigma model. A similar structure arises in the
four-dimensional Yang--Mills theory as well.


title: A Generalized Backward Equation For One Dimensional Processes

abstract:
  Suppose that a real valued process X is given as a solution to a stochastic
differential equation. Then, for any twice continuously differentiable function
f, the backward Kolmogorov equation gives a condition for f(t,X) to be a local
martingale.
  We generalize the backward equation in two main ways. First, it is extended
to non-differentiable functions. Second, the process X is not required to
satisfy an SDE. Instead, it is only required to be a quasimartingale satisfying
an integrability condition, and the martingale condition for f(t,X) is then
expressed in terms of the marginal distributions, drift measure and jumps of X.
The proof involves the stochastic calculus of Dirichlet processes and a
time-reversal argument.
  These results are then applied to show that a continuous and strong Markov
martingale is uniquely determined by its marginal distributions.


title: Electromagnetic radiation in even-dimensional spacetimes

abstract:
  The basic concepts and mathematical constructions of the Maxwell--Lorentz
electrodynamics in flat spacetime of an arbitrary even dimension $d=2n$ are
briefly reviewed. We show that the retarded field strength ${\cal
F}^{(2n)}_{\mu\nu}$ due to a point charge living in a $2n$-dimensional world
can be algebraically expressed in terms of the retarded vector potentials
${\cal A}^{(2m)}_{\mu}$ generated by this charge as if it were accommodated in
$2m$-dimensional worlds nearby, $2\le m\le n+1$. With this finding, the rate of
radiated energy-momentum of the electromagnetic field takes a compact form.


title: Correlation functions of the open XXZ chain II

abstract:
  We derive compact multiple integral formulas for several physical spin
correlation functions in the semi-infinite XXZ chain with a longitudinal
boundary magnetic field. Our formulas follow from several effective
re-summations of the multiple integral representation for the elementary blocks
obtained in our previous article (I). In the free fermion point we compute the
local magnetization as well as the density of energy profiles. These
quantities, in addition to their bulk behavior, exhibit Friedel type
oscillations induced by the boundary; their amplitudes depend on the boundary
magnetic field and decay algebraically in terms of the distance to the
boundary.

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


title:
Fourfold degenerate columnar-dimer ground state in square lattice
  antiferromagnets

abstract:
  We construct and study two frustrated quantum spin-1/2 models on square
lattice, which are like the antiferromagnetic $J_1$-$J_2$ model with some
additional four-spin exchange interactions. These models admit an exactly
solvable case in which the ground state consists of four degenerate
columnar-dimer singlet (CDS) configurations. Away from the exact case, we
employ bond-operator mean-field theory to investigate the evolution of the
ground state by varying the interaction parameters. The mean-field calculation
reveals a quantum phase diagram in which the CDS phase undergoes a continuous
phase transition to either N\'eel or collinear ordered antiferromagnetic
phases.


title: Weighting Di-Boson Monte Carlo Events in Hadron Colliders

abstract:
  A detailed study of the di-boson Monte Carlo programs Pythia, MC@NLO and the
program of Baur, Han and Ohnemus (BHO) is performed. None of these programs
cover all aspects of di-boson production. The BHO code is used to produce event
weights emulating anomalous triple gauge couplings in Pythia and MC@NLO events.
In the same way, boson spin information which is missing for most di-boson
channels in MC@NLO can be introduced as well. This weighting code can be used
to study systematic effects related to various aspects of the Monte Carlo
generators, e.g. parton distribution functions. A detailed study comparing
distributions of event samples generated with these three generators shows a
nice agreement for events without jets. Some differences between the three
samples are observed for events with jets. Most of these differences can be
attributed to the different ways of jet production in the three programs.


title: Resonant interactions of nonlinear water waves in a finite basin

abstract:
  We study exact four-wave resonances among gravity water waves in a square box
with periodic boundary conditions. We show that these resonant quartets are
linked with each other by shared Fourier modes in such a way that they form
independent clusters. These clusters can be formed by two types of quartets:
(1) {\it angle-resonances} which cannot directly cascade energy but which can
redistribute it among the initially excited modes and (2) {\it
scale-resonances} which are much more rare but which are the only ones that can
transfer energy between different scales. We find such resonant quartets and
their clusters numerically on the set of 1000 x 1000 modes, classify and
quantify them and discuss consequences of the obtained cluster structure for
the wavefield evolution. Finite box effects and associated resonant interaction
among discrete wave modes appear to be important in most numerical and
laboratory experiments on the deep water gravity waves, and our work is aimed
at aiding the interpretation of the experimental and numerical data.


title: Higher Order Riesz Transforms for Laguerre Expansions

abstract:
  In this paper we investigate Lp-boundedness properties for the higher order
Riesz transforms associated with Laguerre operators. Also we prove that the
k-th Riesz transform is a principal value singular integral operator (modulus a
constant times of the function when k is even). To establish our results we
exploit a new identity connecting Riesz transforms in the Hermite and Laguerre
settings.


title:
Measurement of the Current-Phase Relation in Josephson Junctions Rhombi
  Chains

abstract:
  We present low temperature transport measurements in one dimensional
Josephson junctions rhombi chains. We have measured the current phase relation
of a chain of 8 rhombi. The junctions are either in the classical phase regime
with the Josephson energy much larger than the charging energy, $E_{J}\gg
E_{C}$, or in the quantum phase regime where $E_{J}/E_{C}\approx 2$. In the
strong Josephson coupling regime ($E_{J}\gg E_{C} \gg k_{B}T$) we observe a
sawtooth-like supercurrent as a function of the phase difference over the
chain. The period of the supercurrent oscillations changes abruptly from one
flux quantum $\Phi_{0}$ to half the flux quantum $\Phi_{0}/2$ as the rhombi are
tuned in the vicinity of full frustration. The main observed features can be
understood from the complex energy ground state of the chain. For
$E_{J}/E_{C}\approx 2$ we do observe a dramatic suppression and rounding of the
switching current dependence which we found to be consistent with the model
developed by Matveev et al.(Phys. Rev. Lett. {\bf 89}, 096802(2002)) for long
Josephson junctions chains.


title: Three-Qubit Groverian Measure

abstract:
  The Groverian measures are analytically computed in various types of
three-qubit states. The final results are also expressed in terms of
local-unitary invariant quantities in each type. This fact reflects the
manifest local-unitary invariance of the Groverian measure. It is also shown
that the analytical expressions for various types have correct limits to other
types. For some types (type 4 and type 5) we failed to compute the analytical
expression of the Groverian measure in this paper. However, from the
consideration of local-unitary invariants we have shown that the Groverian
measure in type 4 should be independent of the phase factor $\phi$, which
appear in the three-qubit state $|\psi>$. This fact with geometric
interpretation on the Groverian measure may enable us to derive the analytical
expressions for general arbitrary three-qubit states in near future.


title:
Diagrammatic approximations for the 2d quantum antiferromagnet: exact
  projection of auxiliary fermions

abstract:
  We present diagrammatic approximations to the spin dynamics of the 2d
Heisenberg antiferromagnet for all temperatures, employing an auxiliary-fermion
representation. The projection onto the physical subspace is effected by
introducing an imaginary-valued chemical potential as proposed by Popov and
Fedotov. The method requires that the fermion number at any lattice site is
strictly conserved. We compare results obtained within a self-consistent
approximation using two different auxiliary-particle projection schemes, (1)
exact and (2) on average. Significant differences between the two are found at
higher temperatures, whereas in the limit of zero temperature (approaching the
magnetically ordered ground state) identical results emerge from (1) and (2),
providing the qualitatively correct dynamical scaling behavior. An
interpretation of these findings is given. We also present in some detail the
derivation of the approximation, which goes far beyond mean-field theory and is
formulated in terms of complex-valued spectral functions of auxiliary fermions.


title:
New analysis on narrow baryon resonance decaying into $pK^0_s$ in
  $pA$-interactions at $70 GeV/c$ with SVD-2 setup

abstract:
  The inclusive reaction $p A \to pK^0_s + X$ was studied at IHEP accelerator
with $70 GeV/c$ proton beam using SVD-2 detector. Two different samples of
$K^0_s$, statistically independent and belonging to different phase space
regions, were used in the analyses and a narrow baryon resonance with the mass
$M=1523\pm 2(stat.)\pm 3(syst.) MeV/c^2$ was observed in both samples of the
data. The combined statistical significance was estimated to be of 8.0 (392
signal over 1990 background events). Using the part of events reconstructed
with better accuracy the width of resonance was constrained to $\Gamma < 14
MeV/c^2$ at 95% C.L. The $x_F$ distribution was found to have a peak at zero
with {$<|x_F|> \approx 0.1$}, that qualitatively agrees to a Regge-based model
predictions. A new cross section estimate of $\sigma \cdot BR(\Theta^+ \to
pK^0) = 4.9 \pm 1.0(stat.) \pm 1.5(syst.) \mu b/nucleon$ for $x_F > 0$ was
obtained.