title: A study on the thermal conductivity of compacted bentonites

abstract:
  Thermal conductivity of compacted bentonite is one of the most important
properties in the design of high-level radioactive waste repositories where
this material is proposed for use as a buffer. In the work described here, a
thermal probe based on the hot wire method was used to measure the thermal
conductivity of compacted bentonite specimens. The experimental results were
analyzed to observe the effects of various factors (i.e. dry density, water
content, hysteresis, degree of saturation and volumetric fraction of soil
constituents) on the thermal conductivity. A linear correlation was proposed to
predict the thermal conductivity of compacted bentonite based on experimentally
observed relationship between the volumetric fraction of air and the thermal
conductivity. The relevance of this correlation was finally analyzed together
with others existing methods using experimental data on several compacted
bentonites.


title: On the recently determined anomalous perihelion precession of Saturn

abstract:
  The astronomer E.V. Pitjeva, by analyzing with the EPM2008 ephemerides a
large number of planetary observations including also two years (2004-2006) of
normal points from the Cassini spacecraft, phenomenologically estimated a
statistically significant non-zero correction to the usual
Newtonian/Einsteinian secular precession of the longitude of the perihelion of
Saturn, i.e. \Delta\dot\varpi_Sat = -0.006 +/- 0.002 arcsec/cy; the formal,
statistical error is 0.0007 arcsec/cy. It can be explained neither by any of
the standard classical and general relativistic dynamical effects
mismodelled/unmodelled in the force models of the EPM2008 ephemerides nor by
several exotic modifications of gravity recently put forth to accommodate
certain cosmological/astrophysical observations without resorting to dark
energy/dark matter. Both independent analyses by other teams of astronomers and
further processing of larger data sets from Cassini will be helpful in
clarifying the nature and the true existence of the anomalous precession of the
perihelion of Saturn.


title:
Tilted Euler characteristic densities for Central Limit random fields,
  with application to "bubbles"

abstract:
  Local increases in the mean of a random field are detected (conservatively)
by thresholding a field of test statistics at a level $u$ chosen to control the
tail probability or $p$-value of its maximum. This $p$-value is approximated by
the expected Euler characteristic (EC) of the excursion set of the test
statistic field above $u$, denoted $\mathbb{E}\varphi(A_u)$. Under isotropy,
one can use the expansion
$\mathbb{E}\varphi(A_u)=\sum_k\mathcal{V}_k\rho_k(u)$, where $\mathcal{V}_k$ is
an intrinsic volume of the parameter space and $\rho_k$ is an EC density of the
field. EC densities are available for a number of processes, mainly those
constructed from (multivariate) Gaussian fields via smooth functions. Using
saddlepoint methods, we derive an expansion for $\rho_k(u)$ for fields which
are only approximately Gaussian, but for which higher-order cumulants are
available. We focus on linear combinations of $n$ independent non-Gaussian
fields, whence a Central Limit theorem is in force. The threshold $u$ is
allowed to grow with the sample size $n$, in which case our expression has a
smaller relative asymptotic error than the Gaussian EC density. Several
illustrative examples including an application to "bubbles" data accompany the
theory.


title: On the non-existence of Tensor Products of Algebraic Cycles

abstract:
  Let $\otimes$ be the map which classifies the tensor product of two line
bundles, an extension of this map to the space of all codimension 1 algebraic
cycles is constructed. It is proved that this extension cannot exist in
codimension greater than 1.


title: Non-Equilibrium Scaling Analysis of the Kondo Model with Voltage Bias

abstract:
  The quintessential description of Kondo physics in equilibrium is obtained
within a scaling picture that shows the buildup of Kondo screening at low
temperature. For the non-equilibrium Kondo model with a voltage bias the key
new feature are decoherence effects due to the current across the impurity. In
the present paper we show how one can develop a consistent framework for
studying the non-equilibrium Kondo model within a scaling picture of
infinitesimal unitary transformations (flow equations). Decoherence effects
appear naturally in third order of the beta-function and dominate the
Hamiltonian flow for sufficiently large voltage bias. We work out the spin
dynamics in non-equilibrium and compare it with finite temperature equilibrium
results. In particular, we report on the behavior of the static spin
susceptibility including leading logarithmic corrections and compare it with
the celebrated equilibrium result as a function of temperature.


title:
On the use of stabilising transformations for detecting unstable
  periodic orbits in the Kuramoto-Sivashinsky equation

abstract:
  In this paper we develop further a method for detecting unstable periodic
orbits (UPOs) by stabilising transformations, where the strategy is to
transform the system of interest in such a way that the orbits become stable.
The main difficulty of using this method is that the number of transformations,
which were used in the past, becomes overwhelming as we move to higher
dimensions (Davidchack and Lai 1999; Schmelcher et al. 1997, 1998). We have
recently proposed a set of stabilising transformations which is constructed
from a small set of already found UPOs (Crofts and Davidchack 2006). The main
benefit of using the proposed set is that its cardinality depends on the
dimension of the unstable manifold at the UPO rather than the dimension of the
system. In a typical situation the dimension of the unstable manifold is much
smaller than the dimension of the system so the number of transformations is
much smaller. Here we extend this approach to high-dimensional systems of ODEs
and apply it to the model example of a chaotic spatially extended system -- the
Kuramoto-Sivashinsky equation. A comparison is made between the performance of
this new method against the competing methods of Newton-Armijo (NA) and
Levernberg-Marquardt (LM). In the latter case, we take advantage of the fact
that the LM algorithm is able to solve under-determined systems of equations,
thus eliminating the need for any additional constraints.


title: Superconductivity at 56 K in Samarium-doped SrFeAsF

abstract:
  We synthesized the samples Sr$_{1-x}$Sm$_x$FFeAs with ZrCuSiAs-type
structure. These samples were characterized by resistivity and susceptibility.
It is found that substitution of rare earth metal for alkaline earth metal in
this system suppresses the anomaly in resistivity and induces
superconductivity. Superconductivity at 56 K in nominal composition
Sr$_{0.5}$Sm$_{0.5}$FFeAs is realized, indicating that the superconducting
transition temperatures in the iron arsenide fluorides can reach as high as
that in oxypnictides with the same structure.


title: Binary and Millisecond Pulsars

abstract:
  We review the main properties, demographics and applications of binary and
millisecond radio pulsars. Our knowledge of these exciting objects has greatly
increased in recent years, mainly due to successful surveys which have brought
the known pulsar population to over 1800. There are now 83 binary and
millisecond pulsars associated with the disk of our Galaxy, and a further 140
pulsars in 26 of the Galactic globular clusters. Recent highlights include the
discovery of the young relativistic binary system PSR J1906+0746, a
rejuvination in globular cluster pulsar research including growing numbers of
pulsars with masses in excess of 1.5 solar masses, a precise measurement of
relativistic spin precession in the double pulsar system and a Galactic
millisecond pulsar in an eccentric (e=0.44) orbit around an unevolved
companion.


title:
Compactified Picard stacks over the moduli stack of stable curves with
  marked points

abstract:
  In this paper we give a construction of algebraic (Artin) stacks endowed with
a modular map onto the moduli stack of n-pointed stable curves of genus g, for
g greater than 2. These stacks are smooth, irreducible and have dimension
4g-3+n, yielding a geometrically meaningful compactification of the degree d
universal Picard stack over the moduli stack of smooth curves with marked
points.


title: A Bayesian Framework for Collaborative Multi-Source Signal Detection

abstract:
  This paper introduces a Bayesian framework to detect multiple signals
embedded in noisy observations from a sensor array. For various states of
knowledge on the communication channel and the noise at the receiving sensors,
a marginalization procedure based on recent tools of finite random matrix
theory, in conjunction with the maximum entropy principle, is used to compute
the hypothesis selection criterion. Quite remarkably, explicit expressions for
the Bayesian detector are derived which enable to decide on the presence of
signal sources in a noisy wireless environment. The proposed Bayesian detector
is shown to outperform the classical power detector when the noise power is
known and provides very good performance for limited knowledge on the noise
power. Simulations corroborate the theoretical results and quantify the gain
achieved using the proposed Bayesian framework.


title: Improved Error Bounds for Dirichlet-to-Neumann Absorbing Boundaries

abstract:
  It has long been known how to construct radiation boundary conditions for the
time dependent wave equation. Although arguments suggesting that they are
accurate have been given, it is only recently that rigorous error bounds have
been proved. Previous estimates show that the error caused by these methods
behaves like epsilon C exp(gamma t) for any gamma > 0. We improve these results
and show that the error behaves like epsilon t^2.


title:
How Polarization and Scattering can reveal Geometries, Dynamics, and
  Feeding of Active Galactic Nuclei

abstract:
  Gaskell et al. (2007) introduced polarization reverberation mapping as a new
technique to explore the structure of active galactic nuclei. We present
modeling results for the time-dependent polarization signal expected from
scattering inside a centrally illuminated spheroid. Such a model setup
describes a larger corona surrounding the compact source of an active nucleus.
Time-delays between the polarized and the total flux are computed and related
to the geometry of the cloud and the viewing angle. When including the in-flow
dynamics of the cloud, it is possible to constrain its optical depth and
velocity, which enables estimations of the mass inflow rate.


title:
Particles Production in Neutron Stars by Means of the Parametric
  Resonance Mechanism

abstract:
  Using a Lagrangean toy model the coupling of a negative pion superconducting
field and the electromagnetic field of the star is analyzed. A numerical study
of particles produced in the neutron star medium by means of the well-known
parametric resonance phenomenon is performed.


title:
2006 Whole Earth Telescope Observations of GD358: A New Look at the
  Prototype DBV

abstract:
  We report on the analysis of 436.1 hrs of nearly continuous high-speed
photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth
Telescope (WET) during the 2006 international observing run, designated XCOV25.
The Fourier transform (FT) of the light curve contains power between 1000 to
4000 microHz, with the dominant peak at 1234 microHz. We find 27 independent
frequencies distributed in 10 modes, as well as numerous combination
frequencies. Our discussion focuses on a new asteroseismological analysis of
GD358, incorporating the 2006 data set and drawing on 24 years of archival
observations. Our results reveal that, while the general frequency locations of
the identified modes are consistent throughout the years, the multiplet
structure is complex and cannot be interpreted simply as l=1 modes in the limit
of slow rotation. The high k multiplets exhibit significant variability in
structure, amplitude and frequency. Any identification of the m components for
the high k multiplets is highly suspect. The k=9 and 8 modes typically do show
triplet structure more consistent with theoretical expectations. The
frequencies and amplitudes exhibit some variability, but much less than the
high k modes. Analysis of the k=9 and 8 multiplet splittings from 1990 to 2008
reveal a long-term change in multiplet splittings coinciding with the 1996
"sforzando" event, where GD358 dramatically altered its pulsation
characteristics on a timescale of hours. We explore potential implications,
including the possible connections between convection and/or magnetic fields
and pulsations. We suggest future investigations, including theoretical
investigations of the relationship between magnetic fields, pulsation, growth
rates, and convection.


title: Communicability in complex brain networks

abstract:
  Recent advances in experimental neuroscience allow, for the first time,
non-invasive studies of the white matter tracts in the human central nervous
system, thus making available cutting-edge brain anatomical data describing
these global connectivity patterns. This new, non-invasive, technique uses
magnetic resonance imaging to construct a snap-shot of the cortical network
within the living human brain. Here, we report on the initial success of a new
weighted network communicability measure in distinguishing local and global
differences between diseased patients and controls. This approach builds on
recent advances in network science, where an underlying connectivity structure
is used as a means to measure the ease with which information can flow between
nodes. One advantage of our method is that it deals directly with the
real-valued connectivity data, thereby avoiding the need to discretise the
corresponding adjacency matrix, that is, to round weights up to 1 or down to 0,
depending upon some threshold value. Experimental results indicate that the new
approach is able to highlight biologically relevant features that are not
immediately apparent from the raw connectivity data.


title:
Enhanced paraconductivity-like fluctuations in the radio frequency
  spectra of ultracold Fermi atoms

abstract:
  Ultracold Fermi atoms allow the realization of the crossover from
Bardeen-Cooper-Schrieffer (BCS) superconductivity to Bose- Einstein
condensation (BEC), by varying with continuity the attraction between fermions
of different species. In this context, radio frequency (RF) spectroscopy
provides a microscopic probe to infer the nature of fermionic pairing. In the
strongly-interacting regime, this pairing affects a wide temperature range
comprising the critical temperature T_c, in analogy to the pseudogap physics
for high-temperature superconductors. By including what are known in
superconductors as "paraconductivity" fluctuations, here we calculate the RF
spectra above T_c for fermions with balanced populations and compare them with
available experimental data, thus revealing that the role of these fluctuations
is considerably enhanced with respect to superconductors. In addition, we
extract from the spectra an energy scale associated with pairing and relate it
to a universal quantity recently introduced for Fermi gases.


title: Continuous trace C*-algebras, gauge groups and rationalization

abstract:
  Let \zeta be an n-dimensional complex matrix bundle over a compact metric
space X and let A_\zeta denote the C*-algebra of sections of this bundle. We
determine the rational homotopy type as an H-space of UA_\zeta, the group of
unitaries of A_\zeta. The answer turns out to be independent of the bundle
\zeta and depends only upon n and the rational cohomology of X. We prove
analogous results for the gauge group and the projective gauge group of a
principal bundle over a compact metric space X.


title: MC@NLO for Heavy Quarks in Photoproduction

abstract:
  An MC@NLO for heavy quarks in photoproduction is presented. This is the first
lepton-hadron process to be included into MC@NLO. To construct an MC@NLO
process dependent so called MC-subtraction terms need to be calculated. The
resulting calculation is compared to a fixed order NLO calculation and the
HERWIG event generator and is shown to perform well.


title: On second quantization on noncommutative spaces with twisted symmetries

abstract:
  By application of the general twist-induced star-deformation procedure we
translate second quantization of a system of bosons/fermions on a symmetric
spacetime in a non-commutative language. The procedure deforms in a coordinated
way the spacetime algebra and its symmetries, the wave-mechanical description
of a system of n bosons/fermions, the algebra of creation and annihilation
operators and also the commutation relations of the latter with functions of
spacetime; our key requirement is the mode-decomposition independence of the
quantum field. In a conservative view, the use of noncommutative coordinates
can be seen just as a way to better express non-local interactions of a special
kind. In a non-conservative one, we obtain a covariant framework for QFT on the
corresponding noncommutative spacetime consistent with quantum mechanical
axioms and Bose-Fermi statistics. One distinguishing feature is that the field
commutation relations remain of the type "field (anti)commutator=a
distribution". We illustrate the results by choosing as examples interacting
non-relativistic and free relativistic QFT on Moyal space(time)s.


title: Transverse momentum of partons: from low to high pT

abstract:
  Transverse-momentum spectra in hard processes are typically described either
in terms of intrinsic transverse momentum of partons, or in terms of
perturbative radiation. The relation between these descriptions is discussed
for the example of semi-inclusive deep inelastic scattering, with special focus
on the angular distribution of the observed hadron. This involves nontrivial
theoretical issues, such as the proper definition of transverse-momentum
dependent parton distributions, and has practical consequences for the
description of pT spectra in phenomenology.


title: Isospin breaking in Kl4 decays

abstract:
  Data on Ke4 decays allow one to extract experimental information on the
elastic pi pi scattering amplitude near threshold, and to confront the outcome
of the analysis with predictions made in the framework of QCD. These
predictions concern an isospin symmetric world, while experiments are carried
out in the real world, where isospin breaking effects - generated by
electromagnetic interactions and by the mass difference of the up and down
quarks - are always present. We discuss the corrections required to account for
these, so that a meaningful comparison with the predictions becomes possible.
In particular, we note that there is a spectacular isospin breaking effect in
Ke4 decays. Once it is taken into account, the previous discrepancy between
NA48/2 data on Ke4 decays and the prediction of pi pi scattering lengths
disappears.


title: Distribution of resonances in the quantum open baker map

abstract:
  We study relevant features of the spectrum of the quantum open baker map. The
opening consists of a cut along the momentum $p$ direction of the 2-torus phase
space, modelling an open chaotic cavity. We study briefly the classical forward
trapped set and analyze the corresponding quantum nonunitary evolution
operator. The distribution of eigenvalues depends strongly on the location of
the escape region with respect to the central discontinuity of this map. This
introduces new ingredients to the association among the classical escape and
quantum decay rates. Finally, we could verify that the validity of the fractal
Weyl law holds in all cases.


title: A random coding theorem for "modulo-two adder" source network

abstract:
  This paper has been withdrawn by the author, due a crucial error in the proof
of the main Theorem (Sec. 3). In particular, in deriving the bound on the
probability of error (Eq. 10) the contribution of those pairs (x', y') that are
not equal to (x, y) has not been considered. By adding the contribution of
these pairs, one can verify that a region of rates similar to the Slepian-Wolf
region will emerge.
  The author would like to acknowledge a critical review of the paper by Mr.
Paul Cuff of Stanford University who first pointed out the error.


title: A maximum entropy approach to OFDM channel estimation

abstract:
  In this work, a new Bayesian framework for OFDM channel estimation is
proposed. Using Jaynes' maximum entropy principle to derive prior information,
we successively tackle the situations when only the channel delay spread is a
priori known, then when it is not known. Exploitation of the time-frequency
dimensions are also considered in this framework, to derive the optimal channel
estimation associated to some performance measure under any state of knowledge.
Simulations corroborate the optimality claim and always prove as good or better
in performance than classical estimators.


title:
Comment on: "The Casimir force on a piston in the spacetime with extra
  compactified dimensions" [Phys. Lett. B 668 (2008) 72]

abstract:
  We offer a clarification of the significance of the indicated paper of H.
Cheng. Cheng's conclusions about the attractive nature of Casimir forces
between parallel plates are valid beyond the particular model in which he
derived them; they are likely to be relevant to other recent literature on the
effects of hidden dimensions on Casimir forces.


title:
Achieving Perfect Imaging beyond Passive and Active Obstacles by a
  Transformed Bilayer Lens

abstract:
  A bilayer lens is proposed based on transformation optics. It is shown that
Pendry's perfect lens, perfect bilayer lens made of indefinite media, and the
concept of compensated media are well unified under the scope of the proposed
bilayer lens. Using this concept, we also demonstrate how one is able to
achieve perfect imaging beyond passive objects or active sources which are
present in front of the lens.


title:
Crowding effects on the mechanical stability and unfolding pathways of
  Ubiquitin

abstract:
  The interior of cells is crowded thus making it important to assess the
effects of macromolecules on the folding of proteins. Using the Self-Organized
Polymer (SOP) model, which is a coarse-grained representation of polypeptide
chains, we probe the mechanical stability of Ubiquitin (Ub) monomers and
trimers ((Ub)$_3$) in the presence of monodisperse spherical crowding agents.
Crowding increases the volume fraction ($\Phi_c$)-dependent average force
($<f_u(\Phi_c)>$), relative to the value at $\Phi_c = 0$, needed to unfold Ub
and the polyprotein. For a given $\Phi_c$, the values of $<f_u(\Phi_c)>$
increase as the diameter ($\sigma_c$) of the crowding particles decreases. The
average unfolding force $<f_u(\Phi_c)>$ depends on the ratio $\frac{D}{R_g}$,
where $D \approx \sigma_c (\frac{\pi}{6 \Phi_c})^{{1/3}}$ with $R_g$ being the
radius of gyration of Ub (or (Ub)$_3$) in the unfolded state. Examination of
the unfolding pathways shows that, relative to $\Phi_c = 0$, crowding promotes
reassociation of ruptured secondary structural elements. Both the nature of the
unfolding pathways and $<f_u(\Phi_c)>$ for (Ub)$_3$ are altered in the presence
of crowding particles with the effect being most dramatic for the subunit that
unfolds last. We predict, based on SOP simulations and theoretical arguments,
that $<f_u(\Phi_c) > \sim \Phi_c^{\frac{1}{3\nu}}$, where $\nu$ is the Flory
exponent that describes the unfolded (random coil) state of the protein.


title: Time variable $\Lambda$ and the accelerating Universe

abstract:
  We perform a deductive study of accelerating Universe and focus on the
importance of variable time-dependent $\Lambda$ in the Einstein's field
equations under the phenomenological assumption, $\Lambda =\alpha H^2$ for the
full physical range of $\alpha$. The relevance of variable $\Lambda$ with
regard to various key issues like dark matter, dark energy, geometry of the
field, age of the Universe, deceleration parameter and barotropic equation of
state has been trivially addressed. The deceleration parameter and the
barotropic equation of state parameter obey a straight line relationship for a
flat Universe described by Friedmann and Raychaudhuri equations. Both the
parameters are found identical for $\alpha = 1$.


title: Notes on Joint Measurability of Quantum Observables

abstract:
  For sharp quantum observables the following facts hold: (i) if we have a
collection of sharp observables and each pair of them is jointly measurable,
then they are jointly measurable all together; (ii) if two sharp observables
are jointly measurable, then their joint observable is unique and it gives the
greatest lower bound for the effects corresponding to the observables; (iii) if
we have two sharp observables and their every possible two outcome
partitionings are jointly measurable, then the observables themselves are
jointly measurable. We show that, in general, these properties do not hold.
Also some possible candidates which would accompany joint measurability and
generalize these apparently useful properties are discussed.


title: Viability of vector-tensor theories of gravity

abstract:
  We present a detailed study of the viability of general vector-tensor
theories of gravity in the presence of an arbitrary temporal background vector
field. We find that there are six different classes of theories which are
indistinguishable from General Relativity by means of local gravity
experiments. We study the propagation speeds of scalar, vector and tensor
perturbations and obtain the conditions for classical stability of those
models. We compute the energy density of the different modes and find the
conditions for the absence of ghosts in the quantum theory. We conclude that
the only theories which can pass all the viability conditions for arbitrary
values of the background vector field are not only those of the pure Maxwell
type, but also Maxwell theories supplemented with a (Lorentz type) gauge fixing
term.


title: Harmonic mean, the Gamma factor and Speed of Light

abstract:
  The relationship between the harmonic mean and special relativity is
concisely elucidated. The arguments in favor and against SRT are explored. It
is shown that the ratio of the speed of light to the harmonic mean of the
onward and return speeds of light in a moving frame under Newtonian mechanics,
when equitably distributed between space and time as a correction, leads to the
Lorentz transformation. This correction implies an apparent contraction of
objects and time dilation. However, the symmetry of the onward and inverse
transformations give a different meaning to the gamma factor


title: Multi-line Doppler imaging of MR Ser in high-state

abstract:
  Doppler images in Balmer, HeI, HeII and CII lines, and simultaneous I-band
photometry of the polar MR Ser are presented and analyzed. The Balmer and
Helium Doppler tomograms of this bright polar at high mass transfer state show
the emission from the accretion flow and the heated surface of the companion
star. As a result of a comparison between the Doppler tomograms the ionization
structure of the flow could be constrained. The highest ionization region was
found in the vicinity of the magnetospheric radius. Photoionization modeling of
the accretion column indicates that the Balmer and Helium emission line
production in this system can be explained by the central soft Xray
illumination only. The orbital ephemeris of MR Ser has been revised.


title: Driving major solar flares and eruptions: a review

abstract:
  This review focuses on the processes that energize and trigger major solar
flares and flux-rope destabilizations. Numerical modeling of specific solar
regions is hampered by uncertain coronal-field reconstructions and by poorly
understood magnetic re- connection; these limitations result in uncertain
estimates of field topology, energy, and helicity. The primary advances in
understanding field destabilizations therefore come from the combination of
generic numerical experiments with interpretation of sets of observations.
These suggest a critical role for the emergence of twisted flux ropes into
pre-existing strong field for many, if not all, of the active regions that pro-
duce M- or X-class flares. The flux and internal twist of the emerging ropes
appear to play as important a role in determining whether an eruption will
develop predom- inantly as flare, confined eruption, or CME, as do the
properties of the embedding field. Based on reviewed literature, I outline a
scenario for major flares and erup- tions that combines flux-rope emergence,
mass draining, near-surface reconnection, and the interaction with the
surrounding field. Whether deterministic forecasting is in principle possible
remains to be seen: to date no reliable such forecasts can be made.
Large-sample studies based on long-duration, comprehensive observations of
active regions from their emergence through their flaring phase are needed to
help us better understand these complex phenomena.


title:
Search for Pair Production of Supersymmetric Top Quarks Mimicking
  Standard Model Top Event Signatures at CDF

abstract:
  We present results of the search for the super-symmetric partner of the top
quark, the stop quark, decaying to a b-quark and chargino with the subsequent
chargino decay into a neutralino, lepton and neutrino. Using the data sample
corresponding to 2.7 inv fb of integrated luminosity, collected with the CDF
Detector of the Tevatron collider, we reconstruct the stop mass of candidate
events and set 95% C. L. upper limits on masses of the stop quark, chargino and
neutralino and the branching ratio of chargino to neutralino+lepton+neutrino.


title: Relation between quantum dwell times and flux-flux correlations

abstract:
  We examine the connection between the dwell time of a quantum particle in a
region of space and flux-flux correlations at the boundaries. It is shown that
the first and second moments of a flux-flux correlation function which
generalizes a previous proposal by Pollak and Miller [E. Pollak and W. H.
Miller, Phys. Rev. Lett. {\bf 53}, 115 (1984)], agree with the corresponding
moments of the dwell-time distribution, whereas the third and higher moments do
not. We also discuss operational approaches and approximations to measure the
flux-flux correlation function and thus the second moment of the dwell time,
which is shown to be characteristically quantum, and larger than the
corresponding classical moment even for freely moving particles.


title: Can the RHIC J/psi puzzle(s) be settled at LHC?

abstract:
  One observes strong suppression effects for hard probes, e.g. the production
of J/psi or high-pT particles, in nucleus-nucleus (AA) collisions at RHIC.
Surprisingly, the magnitude of the suppression is quite similar to that at SPS.
In order to establish whether these features arise due to the presence of a
thermalized system of quarks and gluons formed in the course of the collision,
one should investigate the impact of suppression mechanisms which do not
explicitly involve such a state. We calculate shadowing for gluons in the
Glauber-Gribov theory and propose a model invoking a rapidity-dependent
absorptive mechanism motivated by energy-momentum conservation effects.
Furthermore, final state suppression due to interaction with co-moving matter
(hadronic or pre-hadronic) has been shown to describe data at SPS. We extend
this model by including the backward reaction channel, i.e. recombination of
open charm, which is estimated directly from pp data at RHIC. Strong
suppression of charmonium both in pA and AA collisions at LHC is predicted.
This is in stark contrast with the predictions of models assuming QGP formation
and thermalization of heavy quarks.


title: The Hilbert Transform of a Measure

abstract:
  Let $\fre$ be a homogeneous subset of $\bbR$ in the sense of Carleson. Let
$\mu$ be a finite positive measure on $\bbR$ and $H_\mu(x)$ its Hilbert
transform. We prove that if $\lim_{t\to\infty} t
\abs{\fre\cap\{x\mid\abs{H_\mu(x)}>t\}}=0$, then $\mu_s(\fre)=0$, where
$\mu_\s$ is the singular part of $\mu$.


title: High-pressure, transport, and thermodynamic properties of CeTe3

abstract:
  We have performed high-pressure, electrical resistivity, and specific heat
measurements on CeTe3 single crystals. Two magnetic phases with nonparallel
magnetic easy axes were detected in electrical resistivity and specific heat at
low temperatures. We also observed the emergence of an additional phase at high
pressures and low temperatures and a possible structural phase transition
detected at room temperature and at 45 kbar, which can possibly be related with
the lowering of the charge-density wave transition temperature known for this
compound.


title: Physical Consequences of a Theory with Dynamical Volume Element

abstract:
  We survey motivation, basic ideas and physical consequences of a theory where
the underlying action involves terms both with the usual volume element
$\sqrt{-g}d^{4}x$ and with the new one $\Phi d^{4}x={4!}d\varphi_{1}\wedge
d\varphi_{2}\wedge d\varphi_{3}\wedge d\varphi_{4}$. The latter may be
interpreted as the 4-form determined on the 4-D space-time manifold (not
necessary Riemannian). Regarding the scalar fields $\varphi_{a} (a=1,...4)$ as
new dynamical variables and proceeding in the first order formalism we realize
the so-called Two Measures Theory which possesses a number of attractive
features. We discuss new physical effects which arise from this theory and in
particular strong gravity effect in high energy physics experiments.


title: An isospectral deformation on an orbifold quotient of a nilmanifold

abstract:
  We construct a Laplace isospectral deformation of metrics on an orbifold
quotient of a nilmanifold. Each orbifold in the deformation contains singular
points with order two isotropy. Isospectrality is obtained by modifying a
generalization of Sunada's Theorem due to DeTurck and Gordon.


title:
Total entropy production fluctuation theorems in a nonequilibrium
  time-periodic steady state

abstract:
  We investigate the total entropy production of a Brownian particle in a
driven bistable system. This system exhibits the phenomenon of stochastic
resonance. We show that in the time-periodic steady state, the probability
density function for the total entropy production satisfies Seifert's integral
and detailed fluctuation theorems over finite time trajectories.


title: Algebra in superextensions of twinic groups

abstract:
  Given a group $X$ we study the algebraic structure of the compact
right-topological semigroup $\lambda(X)$ consisting of maximal linked systems
on $X$. This semigroup contains the semigroup $\beta(X)$ of ultrafilters as a
closed subsemigroup. We construct a faithful representation of the semigroup
$\lambda(X)$ in the semigroup of all self-maps of the power-set of $X$ and
using this representation describe the structure of minimal ideal and minimal
left ideals of $\lambda(X)$ for each twinic group $X$. The class of twinic
groups includes all amenable groups and all groups with periodic commutators
but does not include the free group with two generators.


title: Spectral and geometric bounds on 2-orbifold diffeomorphism type

abstract:
  We show that a Laplace isospectral family of two dimensional Riemannian
orbifolds, sharing a lower bound on sectional curvature, contains orbifolds of
only a finite number of orbifold category diffeomorphism types. We also show
that orbifolds of only finitely many orbifold diffeomorphism types may arise in
any collection of 2-orbifolds satisfying lower bounds on sectional curvature
and volume, and an upper bound on diameter. An argument converting spectral
data to geometric bounds shows that the first result is a consequence of the
second.


title:
Self organized mode locking effect in superconductor / ferromagnet
  hybrids

abstract:
  The vortex dynamics in a low temperature superconductor deposited on top of a
rectangular array of micrometer size permalloy triangles is investigated
experimentally. The rectangular unit cell is such that neighboring triangles
physically touch each other along one direction. This design stabilizes
remanent states which differ from the magnetic vortex state typical of
individual non-interacting triangles. Magnetic Force Microscopy images have
revealed that the magnetic landscape of the template can be switched to an
ordered configuration after magnetizing the sample with an in-plane field. The
ordered phase exhibits a broad flux flow regime with relatively low critical
current and a highly anisotropic response. This behavior is caused by the
spontaneous formation of two separated rows of vortices and antivortices along
each line of connected triangles. The existence of a clear flux flow regime
even for zero external field supports this interpretation. The density of
induced vortex-antivortex pairs is directly obtained using a high frequency
measurement technique which allows us to resolve the discrete motion of
vortices. Strikingly, the presence of vortex-antivortex rows gives rise to a
self organized synchronized motion of vortices which manifests itself as field
independent Shapiro steps in the current-voltage characteristics.


title: Grid graphs and lattice surfaces

abstract:
  First, we apply Thurston's construction of pseudo-Anosov homeomorphisms to
grid graphs and obtain translation surfaces whose Veech groups are
commensurable to $(m,n,\infty)$ triangle groups. These surfaces were first
discovered by Bouw and M\"oller, however our treatment of the surfaces differs.
We construct these surfaces by gluing together polygons in two ways. We use
these elementary descriptions to compute the Veech groups, resolve primitivity
questions, and describe the surfaces algebraically. Second, we show that some
$(m,n, \infty)$ triangle groups can not arise as Veech groups. This generalizes
work of Hubert and Schmidt.


title: The instability of downside risk measures

abstract:
  We study the feasibility and noise sensitivity of portfolio optimization
under some downside risk measures (Value-at-Risk, Expected Shortfall, and
semivariance) when they are estimated by fitting a parametric distribution on a
finite sample of asset returns. We find that the existence of the optimum is a
probabilistic issue, depending on the particular random sample, in all three
cases. At a critical combination of the parameters of these problems we find an
algorithmic phase transition, separating the phase where the optimization is
feasible from the one where it is not. This transition is similar to the one
discovered earlier for Expected Shortfall based on historical time series. We
employ the replica method to compute the phase diagram, as well as to obtain
the critical exponent of the estimation error that diverges at the critical
point. The analytical results are corroborated by Monte Carlo simulations.


title:
Diffusion limit for many particles in a periodic stochastic acceleration
  field

abstract:
  The one-dimensional motion of any number $\cN$ of particles in the field of
many independent waves (with strong spatial correlation) is formulated as a
second-order system of stochastic differential equations, driven by two Wiener
processes. In the limit of vanishing particle mass ${\mathfrak{m}} \to 0$, or
equivalently of large noise intensity, we show that the momenta of all $N$
particles converge weakly to $N$ independent Brownian motions, and this
convergence holds even if the noise is periodic. This justifies the usual
application of the diffusion equation to a family of particles in a unique
stochastic force field. The proof rests on the ergodic properties of the
relative velocity of two particles in the scaling limit.

categories: math.PR math-ph math.MP nlin.CD physics.plasm-ph


title: Optimal cross-validation in density estimation with the $L^2$-loss

abstract:
  We analyze the performance of cross-validation (CV) in the density estimation
framework with two purposes: (i) risk estimation and (ii) model selection. The
main focus is given to the so-called leave-$p$-out CV procedure (Lpo), where
$p$ denotes the cardinality of the test set. Closed-form expressions are
settled for the Lpo estimator of the risk of projection estimators. These
expressions provide a great improvement upon $V$-fold cross-validation in terms
of variability and computational complexity. From a theoretical point of view,
closed-form expressions also enable to study the Lpo performance in terms of
risk estimation. The optimality of leave-one-out (Loo), that is Lpo with $p=1$,
is proved among CV procedures used for risk estimation. Two model selection
frameworks are also considered: estimation, as opposed to identification. For
estimation with finite sample size $n$, optimality is achieved for $p$ large
enough [with $p/n=o(1)$] to balance the overfitting resulting from the
structure of the model collection. For identification, model selection
consistency is settled for Lpo as long as $p/n$ is conveniently related to the
rate of convergence of the best estimator in the collection: (i) $p/n\to1$ as
$n\to+\infty$ with a parametric rate, and (ii) $p/n=o(1)$ with some
nonparametric estimators. These theoretical results are validated by simulation
experiments.


title: THH of Thom spectra that are E_\infty ring spectra

abstract:
  We identify the topological Hochschild homology (THH) of the Thom spectrum
associated to an E_\infty classifying map X -> BG, for G an appropriate group
or monoid (e.g. U, O, and F). We deduce the comparison from the observation of
McClure, Schwanzl, and Vogt that THH of a cofibrant commutative S-algebra
(E_\infty ring spectrum) R can be described as an indexed colimit together with
a verification that the Lewis-May operadic Thom spectrum functor preserves
indexed colimits. We prove a splitting result THH(Mf) \htp Mf \sma BX_+ which
yields a convenient description of THH(MU). This splitting holds even when the
classifying map f: X -> BG is only a homotopy commutative A_\infty map,
provided that the induced multiplication on Mf extends to an E_\infty ring
structure; this permits us to recover Bokstedt's calculation of THH(HZ).


title:
Chandra Acis Survey of X-Ray Point Sources in 383 Nearby Galaxies I. the
  Source Catalog

abstract:
  The Chandra data archive after eight years' accumulation is a treasure for
various studies, and in this paper we exploit this valuable resource to study
the X-ray point source populations in nearby galaxies. By December 14, 2007,
383 galaxies within 40 Mpc with isophotal major axis above 1 arcminute have
been observed by 626 public ACIS observations, 60% of which are for the first
time analyzed by this survey to study the X-ray point sources. Uniform data
analysis procedures are applied to the 626 ACIS observations and lead to the
detection of 28099 point sources, which belong to 17599 independent sources.
These include 8700 sources observed twice or more and 1000 sources observed 10
times or more, providing us a wealth of data to study the long term variability
of these X-ray sources. Cross correlation of these sources with galaxy
isophotes led to 8519 sources within the D25 isophotes of 351 galaxies, 3305
sources between the D25 and 2D25 isophotes of 309 galaxies, and additionally
5735 sources outside 2D25 isophotes of galaxies. This survey has produced a
uniform catalog, by far the largest, of 11824 X-ray point sources within 2D25
isophotes of 380 galaxies with 71% of them reported for the first time. With a
uniform dataset and good statistics, this survey enables future works on
various topics, such as X-ray luminosity functions, and multiwavelength
identification and classification.


title: Floer homology on the extended moduli space

abstract:
  Starting from a Heegaard splitting of a three-manifold, we use Lagrangian
Floer homology to construct a three-manifold invariant, in the form of a
relatively Z/8-graded abelian group. Our motivation is to have a well-defined
symplectic side of the Atiyah-Floer Conjecture, for arbitrary three-manifolds.
The symplectic manifold used in the construction is the extended moduli space
of flat SU(2)-connections on the Heegaard surface. An open subset of this
moduli space carries a symplectic form, and each of the two handlebodies in the
decomposition gives rise to a Lagrangian inside the open set. In order to
define their Floer homology, we compactify the open subset by symplectic
cutting; the resulting manifold is only semipositive, but we show that one can
still develop a version of Floer homology in this setting.


title: The mechanism of ion induced amorphization in Si

abstract:
  Some results on damage build up in, and amorphization of, Si, induced by
25-30 keV Al$_5^-$, Si$_5^-$ and Cs$^-$ ions, at room temperature, are
reported. We show that at low energy, amorphization is a nucleation and growth
process, based on the direct impact mechanism. With an Avrami exponent $\sim
1.6$, the growth towards amorphization seems to be diffusion limited. A
transition to a completely amorphized state is indicated at a dose exceeding 17
eV/atom, which is higher than 6-12 eV/atom as predicted by simulations. The
observed higher threshold could be due to temperature effects although an
underestimation of keV-energy recoils, in simulation, may not be ruled out.


title: Hunting for the strangeness content of the nucleon

abstract:
  We present results for the strangeness contribution to the nucleon, <N|ss|N>,
and to the spin of the nucleon, Delta s. By combining several variance
reduction techniques for all-to-all propagators we are able to obtain gains in
terms of computer time of factors of 25-30 for the disconnected loop that is
needed within the calculation of Delta s, relative to the standard approach of
just employing time partitioning/dilution. For <N|ss|n>, the error is dominated
by the gauge noise.


title: Convexity and smoothness of Banach spaces with numerical index one

abstract:
  We show that a Banach space with numerical index one cannot enjoy good
convexity or smoothness properties unless it is one-dimensional. For instance,
it has no WLUR points in its unit ball, its norm is not Frechet smooth and its
dual norm is neither smooth nor strictly convex. Actually, these results also
hold if the space has the (strictly weaker) alternative Daugavet property. We
construct a (non-complete) strictly convex predual of an infinite-dimensional
$L_1$ space (which satisfies a property called lushness which implies numerical
index~1). On the other hand, we show that a lush real Banach space is neither
strictly convex nor smooth, unless it is one-dimensional. In particular, if a
subspace $X$ of the real space $C[0,1]$ is smooth or strictly convex, then
$C[0,1]/X$ contains a copy of $C[0,1]$. Finally, we prove that the dual of any
lush infinite-dimensional real space contains a copy of $\ell_1$.


title:
Classical metric Diophantine approximation revisited: the
  Khintchine-Groshev theorem

abstract:
  Under the assumption that the approximating function $\psi$ is monotonic, the
classical Khintchine-Groshev theorem provides an elegant probabilistic
criterion for the Lebesgue measure of the set of $\psi$-approximable matrices
in $\R^{mn}$. The famous Duffin-Schaeffer counterexample shows that the
monotonicity assumption on $\psi$ is absolutely necessary when $m=n=1$. On the
other hand, it is known that monotonicity is not necessary when $n > 2$
(Sprindzuk) or when $n=1$ and $m>1$ (Gallagher). Surprisingly, when $n=2$ the
situation is unresolved. We deal with this remaining case and thereby remove
all unnecessary conditions from the classical Khintchine-Groshev theorem. This
settles a multi-dimensional analogue of Catlin's Conjecture.


title: De Broglie-Bohm Pilot-Wave Theory: Many Worlds in Denial?

abstract:
  We reply to claims (by Deutsch, Zeh, Brown and Wallace) that the pilot-wave
theory of de Broglie and Bohm is really a many-worlds theory with a superfluous
configuration appended to one of the worlds. Assuming that pilot-wave theory
does contain an ontological pilot wave (a complex-valued field in configuration
space), we show that such claims arise from not interpreting pilot-wave theory
on its own terms. Specifically, the theory has its own ('subquantum') theory of
measurement, and in general describes a 'nonequilibrium' state that violates
the Born rule. Furthermore, in realistic models of the classical limit, one
does not obtain localised pieces of an ontological pilot wave following
alternative macroscopic trajectories: from a de Broglie-Bohm viewpoint,
alternative trajectories are merely mathematical and not ontological. Thus,
from the perspective of pilot-wave theory itself, many worlds are an illusion.
It is further argued that, even leaving pilot-wave theory aside, the theory of
many worlds is rooted in the intrinsically unlikely assumption that quantum
measurements should be modelled on classical measurements, and is therefore
unlikely to be true.


title: When are two algorithms the same?

abstract:
  People usually regard algorithms as more abstract than the programs that
implement them. The natural way to formalize this idea is that algorithms are
equivalence classes of programs with respect to a suitable equivalence
relation. We argue that no such equivalence relation exists.


title:
Common gauge origin of discrete symmetries in observable sector and
  hidden sector

abstract:
  An extra Abelian gauge symmetry is motivated in many new physics models in
both supersymmetric and nonsupersymmetric cases. Such a new gauge symmetry may
interact with both the observable sector and the hidden sector. We
systematically investigate the most general residual discrete symmetries in
both sectors from a common Abelian gauge symmetry. Those discrete symmetries
can ensure the stability of the proton and the dark matter candidate. A hidden
sector dark matter candidate (lightest U-parity particle or LUP) interacts with
the standard model fields through the gauge boson Z', which may selectively
couple to quarks or leptons only. We make a comment on the implications of the
discrete symmetry and the leptonically coupling dark matter candidate, which
has been highlighted recently due to the possibility of the simultaneous
explanation of the DAMA and the PAMELA results. We also show how to construct
the most general U(1) charges for a given discrete symmetry, and discuss the
relation between the U(1) gauge symmetry and R-parity.


title: Dispersion of Magnetic Fields in Molecular Clouds. I

abstract:
  We describe a method for determining the dispersion of magnetic field vectors
about large-scale fields in turbulent molecular clouds. The method is designed
to avoid inaccurate estimates of magnetohydrodynamic or turbulent dispersion -
and help avoiding inaccurate estimates of field strengths - due to large-scale,
non-turbulent field structure when using the well-known method of Chandrasekhar
and Fermi. Our method also provides accurate, independent estimates of the
turbulent to large-scale magnetic field strength ratio. We discuss applications
to the molecular clouds OMC-1, M17, and DR21(Main).


title: Nonlocal Inflation

abstract:
  We consider the possibility of realizing inflation in nonlocal field theories
containing infinitely many derivatives. Such constructions arise naturally in
string field theory and also in a number of toy models, such as the p-adic
string. After reviewing the complications (ghosts and instabilities) that arise
when working with high derivative theories we discuss the initial value problem
and perturbative stability of theories with infinitely many derivatives. Next,
we examine the inflationary dynamics and phenomenology of such theories.
Nonlocal inflation can proceed even when the potential is naively too steep and
generically predicts large nongaussianity in the Cosmic Microwave Background.


title: On the solar nickel and oxygen abundances

abstract:
  Determinations of the solar oxygen content relying on the neutral forbidden
transition at 630 nm depend upon the nickel abundance, due to a Ni I blend.
Here we rederive the solar nickel abundance, using the same ab initio 3D
hydrodynamic model of the solar photosphere employed in the recent revision of
the abundances of C, N, O and other elements. Using 17 weak, unblended lines of
Ni I together with the most accurate atomic and observational data available we
find log epsilon_Ni = 6.17 +/- 0.02 (statistical) +/- 0.05 (systematic), a
downwards shift of 0.06 to 0.08 dex relative to previous 1D-based abundances.
We investigate the implications of the new nickel abundance for studies of the
solar oxygen abundance based on the [O I] 630 nm line in the quiet Sun.
Furthermore, we demonstrate that the oxygen abundance implied by the recent
sunspot spectropolarimetric study of Centeno & Socas-Navarro needs to be
revised downwards from log epsilon_O = 8.86 +/- 0.07 to 8.71 +/- 0.10. This
revision is based on the new nickel abundance, application of the best
available gf-value for the 630 nm forbidden oxygen line, and a more transparent
treatment of CO formation. Determinations of the solar oxygen content relying
on forbidden lines now appear to converge around log epsilon_O = 8.7.


title: Time Evolution of Entropy in Gravitational Collapse

abstract:
  We study the time evolution of the entropy of a collapsing spherical domain
wall, from the point of view of an asymptotic observer, by investigating the
entropy of the entire system (i.e. domain wall and radiation) and induced
radiation alone during the collapse. By taking the difference, we find the
entropy of the collapsing domain wall, since this is the object which will form
a black hole. We find that for large values of time (times larger than
$t/R_s\approx8$), the entropy of the collapsing domain wall is a constant,
which is of the same order as the Bekenstein-Hawking entropy.


title: Moduli of Parabolic Higgs Bundles and Atiyah Algebroids

abstract:
  In this paper we study the geometry of the moduli space of (non-strongly)
parabolic Higgs bundles over a Riemann surface with marked points. We show that
this space possesses a Poisson structure, extending the one on the dual of an
Atiyah algebroid over the moduli space of parabolic vector bundles. By
considering the case of full flags, we get a Grothendieck-Springer resolution
for all other flag types, in particular for the moduli spaces of twisted Higgs
bundles, as studied by Markman and Bottacin and used in the recent work of
Laumon-Ng\^o. We discuss the Hitchin system, and demonstrate that all these
moduli spaces are integrable systems in the Poisson sense.


title: DIS in AdS

abstract:
  We calculate the total cross section for the scattering of a
quark--anti-quark dipole on a large nucleus at high energy for a strongly
coupled N=4 super Yang-Mills theory using AdS/CFT correspondence. We model the
nucleus by a metric of a shock wave in AdS_5. We then calculate the expectation
value of the Wilson loop (the dipole) by finding the extrema of the Nambu-Goto
action for an open string attached to the quark and antiquark lines of the loop
in the background of an AdS_5 shock wave. We find two physically meaningful
extremal string configurations. For both solutions we obtain the forward
scattering amplitude N for the quark dipole--nucleus scattering. We study the
onset of unitarity with increasing center-of-mass energy and transverse size of
the dipole: we observe that for both solutions the saturation scale Q_s is
independent of energy/Bjorken-x and depends on the atomic number of the nucleus
as Q_s ~ A^{1/3}. Finally we observe that while one of the solutions we found
corresponds to the pomeron intercept of \alpha_P = 2 found earlier in the
literature, when extended to higher energy or larger dipole sizes it violates
the black disk limit. The other solution we found respects the black disk limit
and yields the pomeron intercept of \alpha_P = 1.5. We thus conjecture that the
right pomeron intercept in gauge theories at strong coupling may be \alpha_P =
1.5.


title: Persistent Queries

abstract:
  We propose a syntax and semantics for interactive abstract state machines to
deal with the following situation. A query is issued during a certain step, but
the step ends before any reply is received. Later, a reply arrives, and later
yet the algorithm makes use of this reply. By a persistent query, we mean a
query for which a late reply might be used. Syntactically, our proposal
involves issuing, along with a persistent query, a location where a late reply
is to be stored. Semantically, it involves only a minor modification of the
existing theory of interactive small-step abstract state machines.


title: Accretion onto the First Stellar Mass Black Holes

abstract:
  The first stars in the universe, forming at redshifts z>15 in minihalos with
masses of order 10^6 Msun, may leave behind black holes as their remnants.
These objects could conceivably serve as "seeds" for much larger black holes
observed at redshifts z~6. We study the growth of the remnant black holes
through accretion including for the first time the emitted accretion radiation
with adaptive mesh refinement cosmological radiation-hydrodynamical
simulations. The effects of photo-ionization and heating dramatically affect
the accretion flow from large scales, resulting in negligible mass growth of
the black hole. We compare cases with the accretion luminosity included and
neglected to show that the accretion radiation drastically changes the
environment within 100 pc of the black hole, where gas temperatures are
increased by an order of magnitude. The gas densities are reduced and further
star formation in the same minihalo prevented for the two hundred million years
of evolution we followed. These calculations show that even without the
radiative feedback included most seed black holes do not gain mass as
efficiently as has been hoped for in previous theories, implying that black
hole remnants of Pop III stars that formed in minihalos are not likely to be
the origin of miniquasars. Most importantly, however, these calculations
demonstrate that if early stellar mass black holes are indeed accreting close
to the Bondi-Hoyle rate with ten percent efficiency they have a dramatic local
effect in regulating star formation in the first galaxies.


title: Gamma-ray Constraints on Dark Matter Annihilation into Charged Particles

abstract:
  Dark matter annihilation into charged particles is necessarily accompanied by
gamma rays, produced via radiative corrections. Internal bremsstrahlung from
the final state particles can produce hard gamma rays up to the dark matter
mass, with an approximately model-independent spectrum. Focusing on
annihilation into electrons, we compute robust upper bounds on the dark matter
self annihilation cross section $<\sigma_A v >_{e^+e^-}$ using gamma ray data
from the Milky Way spanning a wide range of energies, $\sim10^{-3} - 10^4$ GeV.
We also compute corresponding bounds for the other charged leptons. We make
conservative assumptions about the astrophysical inputs, and demonstrate how
our derived bounds would be strengthened if stronger assumptions about these
inputs are adopted. The fraction of hard gamma rays near the endpoint
accompanying annihilation to $e^+e^-$ is only a factor of $\alt 10^2$ lower
than for annihilation directly to monoenergetic gamma rays. The bound on
$<\sigma_A v >_{e^+e^-}$ is thus weaker than that for $<\sigma_A v
>_{\gamma\gamma}$ by this same factor. The upper bounds on the annihilation
cross sections to charged leptons are compared with an upper bound on the {\it
total} annihilation cross section defined by neutrinos.


title:
Density Studies of MHD Interstellar Turbulence: Statistical Moments,
  Correlations and Bispectrum

abstract:
  We present a number of statistical tools for obtaining studying turbulence in
molecular clouds and diffuse interstellar medium. For our tests we used of
three-dimensional 512 cube compressible MHD isothermal simulations performed
for different sonic and Alfvenic Mach numbers. We introduce the bispectrum, a
new tool for statistical studies of the interstellar medium which, unlike an
ordinary power spectrum of turbulence, preserves the phase information of the
stochastic field. We show that the bispectra of the 3D stochastic density field
and of column densities, available from observations, are similar. We use the
bispectrum technique to define the role of non-linear wave-wave interactions in
the turbulent energy cascade. We also obtained the bispectrum function for
density and column densities with varying magnetic field strength. Larger
values of sonic Mach number result in increased correlations for modes with
different wavenumbers. This effect becomes more evident with increasing
magnetic field intensity. In addition to the bispectrum, we calculated the 3rd
and 4th statistical moments of density and column density, namely, skewness and
kurtosis, respectively. We found a strong dependence of skewness and kurtosis
with the sonic Mach number. In particular, as this number increases, so does
the asymmetry of the density distribution. We also studied the correlations of
2D column density with dispersion of velocities and magnetic field, as well as
the correlations of 3D density with magentic and kinetic energy and Alfven Mach
number for comparison. Our results show that column density is linearly
correlated with magnetic field for high sonic Mach number. This trend is
independent of the turbulent kinetic energy and can be used to characterize
inhomogeneities of physical properties in low density clumps in the ISM.


title: Distributed Constrained Optimization with Semicoordinate Transformations

abstract:
  Recent work has shown how information theory extends conventional
full-rationality game theory to allow bounded rational agents. The associated
mathematical framework can be used to solve constrained optimization problems.
This is done by translating the problem into an iterated game, where each agent
controls a different variable of the problem, so that the joint probability
distribution across the agents' moves gives an expected value of the objective
function. The dynamics of the agents is designed to minimize a Lagrangian
function of that joint distribution. Here we illustrate how the updating of the
Lagrange parameters in the Lagrangian is a form of automated annealing, which
focuses the joint distribution more and more tightly about the joint moves that
optimize the objective function. We then investigate the use of
``semicoordinate'' variable transformations. These separate the joint state of
the agents from the variables of the optimization problem, with the two
connected by an onto mapping. We present experiments illustrating the ability
of such transformations to facilitate optimization. We focus on the special
kind of transformation in which the statistically independent states of the
agents induces a mixture distribution over the optimization variables. Computer
experiment illustrate this for $k$-sat constraint satisfaction problems and for
unconstrained minimization of $NK$ functions.


title:
The OPTX Project I: The Flux and Redshift Catalogs for the CLANS,
  CLASXS, and CDF-N fields

abstract:
  We present the redshift catalogs for the X-ray sources detected in the
Chandra Deep Field North (CDF-N), the Chandra Large Area Synoptic X-ray Survey
(CLASXS), and the Chandra Lockman Area North Survey (CLANS). The catalogs for
the CDF-N and CLASXS fields include redshifts from previous work, while the
redshifts for the CLANS field are all new. For fluxes above 10^-14 ergs cm^-2
s^-1 (2-8 keV) we have redshifts for 76% of the sources. We extend the redshift
information for the full sample using photometric redshifts. The goal of the
OPTX Project is to use these three surveys, which are among the most
spectroscopically complete surveys to date, to analyze the effect of spectral
type on the shape and evolution of the X-ray luminosity functions and to
compare the optical spectral types with the X-ray spectral properties.
  We also present the CLANS X-ray catalog. The nine ACIS-I fields cover a solid
angle of ~0.6 square degrees and reach fluxes of 7x10^-16 ergs cm^-2 s^-1
(0.5-2 keV) and 3.5x10^-15 ergs cm^-2 s^-1 (2-8 keV). We find a total of 761
X-ray point sources. Additionally, we present the optical and infrared
photometric catalog for the CLANS X-ray sources, as well as updated optical and
infrared photometric catalogs for the X-ray sources in the CLASXS and CDF-N
fields.
  The CLANS and CLASXS surveys bridge the gap between the ultradeep pencil-beam
surveys, such as the CDFs, and the shallower, very large-area surveys. As a
result, they probe the X-ray sources that contribute the bulk of the 2-8 keV
X-ray background and cover the flux range of the observed break in the
logN-logS distribution. We construct differential number counts for each
individual field and for the full sample.


title: Digging Into the Surface of the Icy Dwarf Planet Eris

abstract:
  We describe optical spectroscopic observations of the icy dwarf planet Eris
with the 6.5 meter MMT telescope and the Red Channel Spectrograph. We report a
correlation, that is at the edge of statistical significance, between blue
shift and albedo at maximum absorption for five methane ice bands. We interpret
the correlation as an increasing dilution of methane ice with another ice
component, probably nitrogen, with increasing depth into the surface.
  We suggest a mechanism to explain the apparent increase in nitrogen with
depth. Specifically, if we are seeing Eris 50 degrees from pole-on (Brown and
Schaller, 2008), the pole we are seeing now at aphelion was in winter darkness
at perihelion. Near perihelion, sublimation could have built up atmospheric
pressure on the sunlit (summer) hemisphere sufficient to drive winds toward the
dark (winter) hemisphere, where the winds would condense. Because nitrogen is
more volatile and scarcer than methane, it sublimated from the sunlit
hemisphere relatively early in the season, so the early summer atmosphere was
nitrogen rich, and so was the ice deposited on the winter pole. Later in the
season, much of the nitrogen was exhausted from the summer pole, but there was
plenty of methane, which continued to sublimate. At this point, the atmosphere
was more depleted in nitrogen, as was the ice freezing out on top of the
earlier deposited nitrogen rich ice.


title:
Properties and selected implications of magnetic turbulence for
  interstellar medium, Local Bubble and solar wind

abstract:
  Astrophysical fluids, including interstellar and interplanetary medium, are
magnetized and turbulent. Their appearance, evolution, and overall properties
are determined by the magnetic turbulence that stirs it. We argue that
examining magnetic turbulence at a fundamental level is vital to understanding
many processes. A point that frequently escapes the attention of researchers is
that magnetic turbulence cannot be confidently understood only using "brute
force" numerical approaches. In this review we illustrate this point on a
number of examples, including intermittent heating of plasma by turbulence,
interactions of turbulence with cosmic rays and effects of turbulence on the
rate of magnetic reconnection. We show that the properties of magnetic
turbulence may vary considerably in various environments, e.g. imbalanced
turbulence in solar wind differs from balanced turbulence and both of these
differ from turbulence in partially ionized gas. Appealing for the necessity of
more observational data on magnetic fields, we discuss a possibility of
studying interplanetary turbulence using alignment of Sodium atoms in the tail
of comets.


title: The Effective Theory of Quintessence: the w<-1 Side Unveiled

abstract:
  We study generic single-field dark energy models, by a parametrization of the
most general theory of their perturbations around a given background, including
higher derivative terms. In appropriate limits this approach reproduces
standard quintessence, k-essence and ghost condensation. We find no general
pathology associated to an equation of state w_Q < -1 or in crossing the
phantom divide w_Q = -1. Stability requires that the w_Q < -1 side of dark
energy behaves, on cosmological scales, as a k-essence fluid with a virtually
zero speed of sound. This implies that one should set the speed of sound to
zero when comparing with data models with w_Q < -1 or crossing the phantom
divide. We summarize the theoretical and stability constraints on the
quintessential plane (1+w_Q) vs. speed of sound squared.


title:
Accurate universal models for the mass accretion histories and
  concentrations of dark matter halos

abstract:
  A large amount of observations have constrained cosmological parameters and
the initial density fluctuation spectrum to a very high accuracy. However,
cosmological parameters change with time and the power index of the power
spectrum varies with mass scale dramatically in the so-called concordance
Lambda CDM cosmology. Thus, any successful model for its structural evolution
should work well simultaneously for various cosmological models and different
power spectra. We use a large set of high-resolution N-body simulations of a
variety of structure formation models (scale-free, standard CDM, open CDM, and
Lambda CDM) to study the mass accretion histories (MAHs), the mass and redshift
dependence of concentrations and the concentration evolution histories of dark
matter halos. We find that there is significant disagreement between the
much-used empirical models in the literature and our simulations. According to
two simple but tight correlations we find from the simulation results, we
develop new empirical models for both the MAHs and the concentration evolution
histories of dark matter halos, and the latter can also be used to predict the
mass and redshift dependence of halo concentrations. These models are accurate
and universal: the same set of model parameters works well for different
cosmological models and for halos of different masses at different redshifts
and the model predictions are highly accurate even when the histories are
traced to very high redshift. These models are also simple and easy to
implement. A web calculator and a user-friendly code to make the relevant
calculations are available from http://www.shao.ac.cn/dhzhao/mandc.html . We
explain why Lambda CDM halos on nearly all mass scales show two distinct phases
in their evolution histories.


title: The Effectiveness of the Kozai Mechanism in the Galactic Centre

abstract:
  I examine the effectiveness of Kozai oscillations in the centres of galaxies
and in particular the Galactic centre using standard techniques from celestial
mechanics. In particular, I study the effects of a stellar bulge potential and
general relativity on Kozai oscillations, which are induced by stellar discs.
Lockmann et al (2008) recently suggested that Kozai oscillations induced by the
two young massive stellar discs in the Galactic centre drives the orbits of the
young stars to large eccentricity ($e\approx 1$). If some of these young
eccentric stars are in binaries, they would be disrupted near pericentre,
leaving one star in a tight orbit around the central SMBH and producing the
S-star population. I find that the {\it spherical} stellar bulge suppresses
Kozai oscillations, when its enclosed mass inside of a test body is of order
the mass in the stellar disc(s). Since the stellar bulge in the Galactic centre
is much larger than the stellar discs, Kozai oscillations {\it due to the
stellar discs} are likely suppressed. Whether Kozai oscillations are induced
from other nonspherical components to the potential (for instance, a flattened
stellar bulge) is yet to be determined.


title:
Sharp Estimates for the $\bar{\partial}$-Neumann Problem on Regular
  Coordinate Domains

abstract:
  This paper treats subelliptic estimates for the $\bar{\partial}$-Neumann
problem on a class of domains known as regular coordinate domains. Our main
result is that the largest subelliptic gain for a regular coordinate domain is
bounded below by a purely algebraic number, the inverse of twice the
multiplicity of the ideal associated to a given boundary point.


title:
A Future High Statistics Charm Mixing Experiment Using the Fermilab
  Tevatron

abstract:
  We present an idea for a future D0-D0bar mixing and CP violation experiment
to run at the Fermilab Tevatron. We estimate that in three years of running,
such an experiment could reconstruct an order of magnitude more flavor-tagged
D0->K+pi- decays than will be reconstructed by the B-factory experiments with
their full data sets. The resulting sensitivity to CP-violating parameters
|q/p| and Arg(q/p) is calculated from a global fit to CP-violating observables,
and it is found to be much greater than current world sensitivity.


title:
Chandra and XMM Observations of the Composite Supernova Remnant
  G327.1-1.1

abstract:
  We present new X-ray imaging and spectroscopy of a composite supernova
remnant G327.1-1.1 using the Chandra and XMM-Newton X-ray observatories.
G327.1-1.1 has an unusual morphology consisting of a symmetric radio shell and
an off center nonthermal component that indicates the presence of a pulsar wind
nebula (PWN). Radio observations show a narrow finger of emission extending
from the PWN structure towards the northwest. X-ray studies with ASCA, ROSAT,
and BeppoSAX revealed elongated extended emission and a compact source at the
tip of the finger that may be coincident with the actual pulsar. The high
resolution Chandra observations provide new insight into the structure of the
inner region of the remnant. The images show a compact source embedded in a
cometary structure, from which a trail of X-ray emission extends in the
southeast direction. The Chandra images also reveal two prong-like structures
that appear to originate from the vicinity of the compact source and extend
into a large bubble that is oriented in the north-west direction, opposite from
the bright radio PWN. The emission from the entire radio shell is detected in
the XMM data and can be characterized by a thermal plasma model with a
temperature of 0.3 keV, which we use to estimate the physical properties of the
remnant. The peculiar morphology of G327.1-1.1 may be explained by the emission
from a moving pulsar and a relic PWN that has been disrupted by the reverse
shock.


title: LISA parameter estimation using numerical merger waveforms

abstract:
  Recent advances in numerical relativity provide a detailed description of the
waveforms of coalescing massive black hole binaries (MBHBs), expected to be the
strongest detectable LISA sources. We present a preliminary study of LISA's
sensitivity to MBHB parameters using a hybrid numerical/analytic waveform for
equal-mass, non-spinning holes. The Synthetic LISA software package is used to
simulate the instrument response and the Fisher information matrix method is
used to estimate errors in the parameters. Initial results indicate that
inclusion of the merger signal can significantly improve the precision of some
parameter estimates. For example, the median parameter errors for an ensemble
of systems with total redshifted mass of one million Solar masses at a redshift
of one were found to decrease by a factor of slightly more than two for signals
with merger as compared to signals truncated at the Schwarzchild ISCO.


title:
Chandra measurements of non-thermal-like X-ray emission from massive,
  merging, radio-halo clusters

abstract:
  We report the discovery of spatially-extended, non-thermal-like emission
components in Chandra X-ray spectra for five of a sample of seven massive,
merging galaxy clusters with powerful radio halos. The emission components can
be fitted by power-law models with mean photon indices in the range 1.5 < Gamma
< 2.0. A control sample of regular, dynamically relaxed clusters, without radio
halos but with comparable mean thermal temperatures and luminosities, shows no
compelling evidence for similar components. Detailed X-ray spectral mapping
reveals the complex thermodynamic states of the radio halo clusters. Our
deepest observations, of the Bullet Cluster 1E 0657-56, demonstrate a spatial
correlation between the strongest power-law X-ray emission, highest thermal
pressure, and brightest 1.34GHz radio halo emission in this cluster. We confirm
the presence of a shock front in the 1E 0657-56 and report the discovery of a
new, large-scale shock front in Abell 2219. We explore possible origins for the
power-law X-ray components. These include inverse Compton scattering of cosmic
microwave background photons by relativistic electrons in the clusters;
bremsstrahlung from supra-thermal electrons energized by Coulomb collisions
with an energetic, nonthermal proton population; and synchrotron emission
associated with ultra-relativistic electrons. Interestingly, we show that the
power-law signatures may also be due to complex temperature and/or metallicity
structure in clusters particularly in the presence of metallicity gradients. In
this case, an important distinguishing characteristic between the radio halo
clusters and control sample of predominantly cool-core clusters is the
relatively low central X-ray surface brightness of the former.


title:
The Gelfand-Zeitlin integrable system and its action on generic elements
  of gl(n) and so(n)

abstract:
  In recent work Bertram Kostant and Nolan Wallach ([KW1], [KW2]) have defined
an interesting action of a simply connected Lie group $A$ isomorphic to
\mathbb{C}^{{n\choose 2}} on gl(n) using a completely integrable system derived
from Gelfand-Zeitlin theory. In this paper we show that an analogous action of
\mathbb{C}^{d} exists on the complex orthogonal Lie algebra so(n), where d is
half the dimension of a regular adjoint orbit in so(n). In [KW1], Kostant and
Wallach describe the orbits of $A$ on a certain Zariski open subset of regular
semisimple elements in gl(n). We extend these results to the case of so(n). We
also make brief mention of the author's results in [Col1], which describe all
$A$-orbits of dimension {n\choose 2} in gl(n).


title: Gamma Ray Astronomy and the Origin of Galactic Cosmic Rays

abstract:
  Diffusive shock acceleration operating at expanding supernova remnant shells
is by far the most popular model for the origin of galactic cosmic rays.
Despite the general consensus received by this model, an unambiguous and
conclusive proof of the supernova remnant hypothesis is still missing. In this
context, the recent developments in gamma ray astronomy provide us with
precious insights into the problem of the origin of galactic cosmic rays, since
production of gamma rays is expected both during the acceleration of cosmic
rays at supernova remnant shocks and during their subsequent propagation in the
interstellar medium. In particular, the recent detection of a number of
supernova remnants at TeV energies nicely fits with the model, but it still
does not constitute a conclusive proof of it, mainly due to the difficulty of
disentangling the hadronic and leptonic contributions to the observed gamma ray
emission. In this paper, the most relevant cosmic-ray-related results of gamma
ray astronomy are briefly summarized, and the foreseeable contribution of
future gamma ray observations to the final solution of the problem of cosmic
ray origin is discussed.


title:
Z4-U(1) crossover of the order parameter symmetry in a two-dimensional
  valence-bond-solid

abstract:
  We discuss ground-state projector simulations of a modified two-dimensional
S=1/2 Heisenberg model in the valence bonds basis. Tuning matrix elements
corresponding to the diagonal and off-diagonal terms in the quantum dimer
model, we show that there is a quantum phase transition from the
antiferromagnet into a columnar valence-bond-solid (VBS). There are no signs of
discontinuities, suggesting a continuous or very weakly first-order transition.
The Z4-symmetric VBS order parameter exhibits an emergent U(1) symmetry as the
phase transition is approached. We extract the associated length-scale
governing the U(1)-Z4 cross-over inside the VBS phase.


title: Wave Packets in Discrete Quantum Phase Space

abstract:
  The properties of quantum mechanics with a discrete phase space are studied.
The minimum uncertainty states are found, and these states become the Gaussian
wave packets in the continuum limit. With a suitably chosen Hamiltonian that
gives free particle motion in the continuum limit, it is found that full or
approximate periodic time evolution can result. This represents an example of
revivals of wave packets that in the continuum limit is the familiar free
particle motion on a line. Finally we examine the uncertainty principle for
discrete phase space and obtain the correction terms to the continuum case.


title: Obtaining Spectra of Turbulent Velocity from Observations

abstract:
  We discuss a long-standing problem of how turbulence can be studied using
observations of Doppler broadened emission and absorption lines. The focus of
the present review is on two new techniques, the Velocity-Channel Analysis
(VCA), which makes use of the channel maps, and the Velocity Coordinate
Spectrum (VCS), which utilizes the fluctuations measured along the velocity
axis of the Position-Position Velocity (PPV) data cubes. Both techniques have
solid theoretical foundations based on analytical calculations as well as on
numerical testings. Among the two the VCS, which has been developed quite
recently, has two unique features. First of all, it is applicable to turbulent
volumes that are not spatially resolved. Second, it can be used with absorption
lines that do not provide good spatial sampling of different lags over the
image of the turbulent object. In fact, recent studies show that measurements
of absorption line along less than 10 absorption directions are sufficient for
a reliable recovering of the underlying spectrum of the turbulence. Moreover,
both weak absorption lines and absorption lines in saturated regime can be
used, which extends the applicability of the technique. Our comparison of the
VCA and the VCS with a more traditional technique of Velocity Centroids shows
that the former two techniques recover reliably the spectra of supersonic
turbulence, while the Velocity Centroids may be used only for studying subsonic
turbulence. We discuss spectra of astrophysical turbulence obtained with the
VCA and the VCS techniques.


title:
A note on the $\hat A$-genus for $\pi_2$-finite manifolds with
  $S^1$-symmetry

abstract:
  We construct examples of $S^1$-manifolds with finite second homotopy group
and non-vanishing $\hat A$-genus. This is related to the classification of
positive quaternionic Kaehler manifolds.


title: Injections of mapping class groups

abstract:
  We construct new monomorphisms between mapping class groups of surfaces. The
first family of examples injects the mapping class group of a closed surface
into that of a different closed surface. The second family of examples are
defined on mapping class groups of once-punctured surfaces and have quite
curious behaviour. For instance, some pseudo-Anosov elements are mapped to
multi-twists. Neither of these two types of phenomena were previously known to
be possible although the constructions are elementary.


title: Charge Conjugation from Space-Time Inversion

abstract:
  We show that the CPT group of the Dirac field emerges naturally from the PT
and P (or T) subgroups of the Lorentz group.


title: High Accuracy Imaging Polarimetry with NICMOS

abstract:
  The ability of NICMOS to perform high accuracy polarimetry is currently
hampered by an uncalibrated residual instrumental polarization at a level of
1.2-1.5%. To better quantify and characterize this residual we obtained
observations of three polarimetric standard stars at three separate space-craft
roll angles. Combined with archival data, these observations were used to
characterize the residual instrumental polarization to enable NICMOS to reach
its full polarimetric potential. Using these data, we calculate values of the
parallel transmission coefficients that reproduce the ground-based results for
the polarimetric standards. The uncertainties associated with the parallel
transmission coefficients, a result of the photometric repeatability of the
observations, dominate the accuracy of p and theta. However, the new
coefficients now enable imaging polarimetry of targets with p~1.0% at an
accuracy of +/-0.6% and +/-15 degrees.


title: On the spin-liquid phase of one dimensional spin-1 bosons

abstract:
  We consider a model of one dimensional spin-1 bosons with repulsive
density-density interactions and antiferromagnetic exchange. We show that the
low energy effective field theory is given by a spin-charge separated theory of
a Tomonaga-Luttinger Hamiltonian and the O(3) nonlinear sigma model describing
collective charge and spin excitations respectively. At a particular ratio of
the density-density to spin-spin interaction the model is integrable, and we
use the exact solutions to provide an independent derivation of the low energy
effective theory. The system is in a superfluid phase made of singlet pairs of
bosons, and we calculate the long-distance asymptotics of certain correlation
functions.


title:
Turbulence Spectra from Doppler-broadened Spectral Lines: Tests of the
  Velocity Channel Analysis and Velocity Coordinate Spectrum Techniques

abstract:
  Turbulent motions induce Doppler shifts of observable emission and absorption
lines motivating studies of turbulence using precision spectroscopy. We provide
the numerical testing of the two most promising techniques, Velocity Channel
Analysis (VCA) and Velocity Coordinate Spectrum (VCS). We obtain an expression
for the shot noise that the discretization of the numerical data entails and
successfully test it. We show that the numerical resolution required for
recovering the underlying turbulent spectrum from observations depend on the
spectral index of velocity fluctuations, which makes low resolution testing
misleading. We demonstrate numerically that, dealing with absorption lines,
sampling of turbulence along just a dozen directions provides a high quality
spectrum with the VCS technique.


title:
Charged Bilepton Pair Production at LHC Including Exotic Quark
  Contribution

abstract:
  The production of $W^+ W^-$ pair in hadron colliders was calculated up to
loop corrections by some authors in the Electroweak standard model (SM)
framework. This production was also calculated, at the tree level, in some
extensions of the SM such as the vector singlet, the fermion mirror fermion and
the vector doublet models by considering the contributions of new neutral gauge
bosons and exotic fermions. The obtained results for $e^+ e^-$ and $pp$
collisions pointed out that the new physics contributions are quite important.
This motivates us to calculate the production of a more massive charged gauge
boson predicted by the ${SU (3)_C \times SU (3)_L \times U (1)_X}$ model (3-3-1
model). Thus, the aim of the present paper is to analyze the role played by of
the extra gauge boson ${Z^\prime}$ and of the exotic quarks, predicted in the
minimal version of the 3-3-1 model, by considering the inclusive production of
a pair of bileptons ($V^\pm$) in the reaction $p + p \longrightarrow V^+ + V^-
+ X$, at the Large Hadron Collider (LHC) energies.
  Our results show that the correct energy behavior of the elementary cross
section follows from the balance between the contributions of the extra neutral
gauge boson with those from the exotic quarks. The extra neutral gauge boson
induces flavor-changing neutral currents (FCNC) at tree level, and we have
introduced the ordinary quark mixing matrices for the model when the first
family transforms differently to the other two with respect to $SU(3)_L$. We
obtain a huge number of heavy bilepton pairs produced for two different values
of the center of mass energy of the LHC.


title: Probing New Physics with Astrophysical Neutrinos

abstract:
  We review the prospects for probing new physics with neutrino astrophysics.
High energy neutrinos provide an important means of accessing physics beyond
the electroweak scale. Neutrinos have a number of advantages over conventional
astronomy and, in particular, carry information encoded in their flavor degree
of freedom which could reveal a variety of exotic neutrino properties. We also
outline ways in which neutrino astrophysics can be used to constrain dark
matter properties, and explain how neutrino-based limits lead to a strong
general bound on the dark matter total annihilation cross-section.


title: On the global well-posedness of the one-dimensional Schrodinger map flow

abstract:
  We establish the global well-posedness of the initial value problem for the
Schrodinger map flow for maps from the real line into Kahler manifolds and for
maps from the circle into Riemann surfaces. This partially resolves a
conjecture of W.-Y. Ding.


title:
Voltage-Controlled Negative Index in Vertically Coupled Quantum Dot
  Systems

abstract:
  We demonstrate that voltage-controlled negative index can be obtained in
self-organized InAs quantum dot systems. As the bias voltage changes, the
refractive index can be adjusted and controlled continuously from -7 to 7.
Simultaneously, the absorption of light in the system will be very small. The
single-negative index materials and the double-negative index materials can be
achieved in different bias voltages.


title:
Different thresholds of bond percolation in scale-free networks with
  identical degree sequence

abstract:
  Generally, the threshold of percolation in complex networks depends on the
underlying structural characterization. However, what topological property
plays a predominant role is still unknown, despite the speculation of some
authors that degree distribution is a key ingredient. The purpose of this paper
is to show that power-law degree distribution itself is not sufficient to
characterize the threshold of bond percolation in scale-free networks. To
achieve this goal, we first propose a family of scale-free networks with the
same degree sequence and obtain by analytical or numerical means several
topological features of the networks. Then, by making use of the
renormalization group technique we determine the threshold of bond percolation
in our networks. We find an existence of non-zero thresholds and demonstrate
that these thresholds can be quite different, which implies that power-law
degree distribution does not suffice to characterize the percolation threshold
in scale-free networks.


title: Solitaire: Recent Developments

abstract:
  This special issue on Peg Solitaire has been put together by John Beasley as
guest editor, and reports work by John Harris, Alain Maye, Jean-Charles
Meyrignac, George Bell, and others. Topics include: short solutions on the 6 x
6 board and the 37-hole "French" board, solving generalized cross boards and
long-arm boards. Five new problems are given for readers to solve, with
solutions provided.


title:
Discrete phase space - I: Variational formalism for classical
  relativistic wave fields

abstract:
  The classical relativistic wave equations are presented as partial difference
equations in the arena of covariant discrete phase space. These equations are
also expressed as difference-differential equations in discrete phase space and
continuous time. The relativistic invariance and covariance of the equations in
both versions are established. The partial difference and
difference-differential equations are derived as the Euler-Lagrange equations
from the variational principle. The difference and difference-differential
conservation equations are derived. Finally, the total momentum, energy, and
charge of the relativistic classical fields satisfying difference-differential
equations are computed.


title:
Discrete phase space - II: The second quantization of free relativistic
  wave fields

abstract:
  The Klein-Gordon equation, the Maxwell equation, and the Dirac equation are
presented as partial difference equations in the eight-dimensional covariant
discrete phase space. These equations are also furnished as
difference-differential equations in the arena of discrete phase space and
continuous time. The scalar field and electromagnetic fields are quantized with
commutation relations. The spin-1/2 field is quantized with anti-commutation
relations. Moreover, the total momentum, energy and charge of these free
relativisitic quantized fields in the discrete phase space and continuous time
are computed exactly. The results agree completely with those computed from the
relativisitic fields defned on the space-time continuum.


title: Discrete phase space - III: The Divergence-free S-matrix elements

abstract:
  In the arena of the discrete phase space and continuous time, the theory of
S-marix is formulated. In the special case of Quantum-Electrodynamics (QED),
the Feynman rules are precisely developed. These rules in the fourmomentum turn
out to be identical to the usual QED, except for the vertex function. The new
vertex function is given by an infinite series which can only be treated in an
asymptotic approximation at the present time. Preliminary approximations prove
that the second order self-energies of a fermion and a photon in the discrete
model have convergent improper integrals. In the final section, a sharper
asymptotic analysis is employed. It is proved that in case the number of
external photon or fermion lines is at least one, then the S-matrix elements
converge in all orders. Moreover, there are no infra-red divergences in this
formulation.


title:
Muonium-Antimuonium Oscillations in an extended Minimal Supersymmetric
  Standard Model with right-handed neutrinos

abstract:
  The electron and muon number violating muonium-antimuonium oscillation
process in an extended Minimal Supersymmetric Standard Model is investigated.
The Minimal Supersymmetric Standard Model is modified by the inclusion of three
right-handed neutrino superfields. While the model allows the neutrino mass
terms to mix among the different generations, the sneutrino and slepton mass
terms have only intra-generation lepton number violation but not
inter-generation lepton number mixing. So doing, the muonium-antimuonium
conversion can then be used to constrain those model parameters which avoid
further constraint from the $\mu\to e\gamma$ decay bounds. For a wide range of
parameter values, the contributions to the muonium-antimuonium oscillation time
scale are at least two orders of magnitude below the sensivity of current
experiments. However, if the ratio of the two Higgs field VEVs, $\tan\beta$, is
very small, there is a limited possibility that the contributions are large
enough for the present experimental limit to provide an inequality relating
$\tan\beta$ with the light neutrino mass scale $m_\nu$ which is generated by
see-saw mechanism. The resultant lower bound on $\tan\beta$ as a function of
$m_\nu$ is more stringent than the analogous bounds arising from the muon and
electron anomalous magnetic moments as computed using this model.


title:
Boundary behavior of special cohomology classes arising from the Weil
  representation

abstract:
  In our previous paper [math.NT/0408050], we established a correspondence
between vector-valued holomorphic Siegel modular forms and cohomology with
local coefficients for local symmetric spaces $X$ attached to real orthogonal
groups of type $(p,q)$. This correspondence is realized using theta functions
associated to explicitly constructed "special" Schwartz forms. Furthermore, the
theta functions give rise to generating series of certain "special cycles" in
$X$ with coefficients.
  In this paper, we study the boundary behaviour of these theta functions in
the non-compact case and show that the theta functions extend to the Borel-Sere
compactification $\bar{X}$ of $X$. However, for the $\Q$-split case for
signature $(p,p)$, we have to construct and consider a slightly larger
compactification, the "big" Borel-Serre compactification. The restriction to
each face of $\bar{X}$ is again a theta series as in [math.NT/0408050], now for
a smaller orthogonal group and a larger coefficient system.
  As application we establish the cohomological nonvanishing of the special
(co)cycles when passing to an appropriate finite cover of $X$. In particular,
the (co)homology groups in question do not vanish.


title:
Complete transfer of populations from a single state to a pre-selected
  superposition of states using Piecewise Adiabatic Passage

abstract:
  We develop a method for executing robust and selective transfer of
populations between a single level and pre-selected superpositions of energy
eigenstates. Viewed in the frequency domain, our method amounts to executing a
series of simultaneous adiabatic passages into each component of the target
superposition state. Viewed in {the} time domain, the method works by
accumulating the wavefunction of the target wave packet as it revisits the
Franck Condon region, in what amounts to an extension of the Piecewise
Adiabatic Passage technique [ Shapiro et.al., Phys. Rev. Lett. 99, 033002
(2007)] to the multi-state regime. The viability of the method is verified by
performing numerical tests for the Na_2 molecule.


title:
Eigenfunctions of spinless particles in a one-dimensional linear
  potential well

abstract:
  In the present paper, we work out the eigenfunctions of spinless particles
bound in a one-dimensional linear finite range, attractive potential well,
treating it as a time-like component of a four-vector. We show that the
one-dimensional stationary Klein-Gordon equation is reduced to a standard
differential equation, whose solutions, consistent with the boundary
conditions, are the parabolic cylinder functions, which further reduce to the
well-known confluent hypergeometric functions.


title:
Unified Rotation Curve of the Galaxy -- Decomposition into de
  Vaucouleurs Bulge, Disk, Dark Halo, and the 9-kpc Rotation Dip --

abstract:
  We present a unified rotation curve of the Galaxy re-constructed from the
existing data by re-calculating the distances and velocities for a set of
galactic constants R_0=8 kpc and V_0=200 km/s. We decompose it into a bulge
with de Vaucouleurs-law profile of half-mass scale radius 0.5 kpc and mass 1.8
x 10^{10}M_{sun}, an exponential disk of scale radius 3.5 kpc of 6.5 x
10^{10}M_{sun}, and an isothermal dark halo of terminal velocity 200 km/s. The
r^{1/4}-law fit was obtained for the first time for the Milky Way's rotation
curve. After fitting by these fundamental structures, two local minima, or the
dips, of rotation velocity are prominent at radii 3 and 9 kpc. The 3-kpc dip is
consistent with the observed bar. It is alternatively explained by a massive
ring with the density maximum at radius 4 kpc. The 9-kpc dip is clearly
exhibited as the most peculiar feature in the galactic rotation curve. We
explain it by a massive ring of amplitude as large as 0.3 to 0.4 times the disk
density with the density peak at radius 11 kpc. This great ring may be related
to the Perseus arm, while no peculiar feature of HI-gas is associated.