title:
The Lyman alpha morphology of local starburst galaxies: release of
  calibrated images

abstract:
  We present reduced and calibrated high resolution Lyman-alpha (Lya) images
for a sample of 6 local star forming galaxies. Targets were selected to
represent a range in luminosity and metallicity and to include both known Lya
emitters and non-emitters. Far ultraviolet imaging was carried out with the
Solar Blind Channel of the ACS on HST in the F122M (Lya on-line) and F140LP
(continuum) filters. The resulting Lya images are the product of careful
modeling of both the stellar and nebular continua, facilitated by supporting
HST imaging in Ha and 5 continuum bands, combined with Starburst99 evolutionary
synthesis models, and prescriptions for dust extinction on the continuum. In
all, the resulting morphologies in Lya, Ha, and UV-continuum are qualitatively
very different and we show that the bulk of Lya emerges in a diffuse component
resulting from resonant scattering events. Lya escape fractions, computed from
integrated Ha luminosities and recombination theory, are found never to exceed
14%. Internal dust extinction is estimated in each pixel and used to correct
Lya fluxes. However, the extinction corrections are far too small (factors from
2.6 to infinity) to reconcile the global Lya luminosities with recombination
theory. Surprisingly, when comparing the global equivalent widths of Lya and
Ha, the two quantities appear anti-correlated, which may be due to the
evolution of mechanical feedback. This calls for caution in the interpretation
of Lya observations. The images presented have a physical resolution 3 orders
of magnitude better than attainable at high-z from the ground with current
instrumentation and our images may therefore serve as useful templates for
comparing with observations and modeling of primeval galaxy formation. We
therefore provide the reduced Lya, Ha, and continuum images to the community.


title: Pre-Hausdorff Spaces

abstract:
  This paper introduces three separation conditions for topological spaces,
called T_{0,1}, T_{0,2} ("pre-Hausdorff"), and T_{1,2}. These conditions
generalize the classical T_(1) and T_(2) separation axioms, and they have
advantages over them topologically which we discuss. We establish several
different characterizations of pre-Hausdorff spaces, and a characterization of
Hausdorff spaces in terms of pre-Hausdorff. We also discuss some classical
Theorems of general topology which can or cannot be generalized by replacing
the Hausdorff condition by pre-Hausdorff.


title:
Continuum subtracting Lyman-alpha images: Low redshift studies using the
  Solar Blind Channel of HST/ACS

abstract:
  [ABRIDGED] We are undertaking an imaging study of local star-forming galaxies
in the Lyman-alpha (Lya) emission line using the Solar Blind Channel (SBC) of
the ACS onboard the HST. Observations have been obtained in Lya and H-alpha
(Ha) and 6 continuum filters between ~1500AA and the I-band. Previously (Hayes
et al 2005) we demonstrated that the production of Lya line-only images in the
SBC-only data-set is non-trivial and that supporting data is a requirement. We
here develop various methods of continuum subtraction and assess their relative
performance using a variety of spectral energy distributions (SED) as input. We
conclude that simple assumptions about the behavior of the ultraviolet
continuum consistently lead to results that are wildly erroneous, and determine
that an SED fitting approach is essential. Moreover, a single component stellar
or stellar+nebular spectrum is not always sufficient for realistic template
SEDs and, in order to successfully recover the input observables, care must be
taken to control contributions of nebular gas and underlying stellar
populations. Independent measurements of the metallicity must first be
obtained, but details of the initial mass function play only a small role. We
identify the need to bin together pixels in our data to obtain signal-to-noise
(S/N) of ~10 in each band before processing. At S/N=10 we can recover Lya
fluxes accurate to ~30% for Lya lines with intrinsic equivalent width [W(Lya)]
of 10AA. This accuracy improves to ~10% for W(Lya)=100AA. We describe the image
processing applied to the observations presented in \"Ostlin et al. (2009) and
the associated data-release. We also present simulations for an observing
strategy for an alternative low-redshift SBC Lya imaging campaign using
adjacent combinations of long-pass filters at slightly higher redshift.


title: QSOs in the combined SDSS/GALEX database

abstract:
  We discuss selection of QSO candidates from the combined SDSS and GALEX
catalogues. We discuss properties of QSOs within the combined sample, and note
uncertainties in number counts and completeness, compared with other SDSS-based
samples. We discuss colour and other properties with redshift within the sample
and the SEDs for subsets. We estimate the numbers of faint QSOs that are
classified as extended objects in the SDSS, and consequent uncertainties that
follow.


title:
The ACS LCID Project: RR Lyrae stars as tracers of old population
  gradients in the isolated dwarf spheroidal galaxy Tucana

abstract:
  We present a study of the radial distribution of RR Lyrae variables, which
present a range of photometric and pulsational properties, in the dwarf
spheroidal galaxy Tucana. We find that the fainter RR Lyrae stars, having a
shorter period, are more centrally concentrated than the more luminous, longer
period RR Lyrae variables. Through comparison with the predictions of
theoretical models of stellar evolution and stellar pulsation, we interpret the
fainter RR Lyrae stars as a more metal-rich subsample. In addition, we show
that they must be older than about 10 Gyr. Therefore, the metallicity gradient
must have appeared very early on in the history of this galaxy.


title: Shear strain localization in elastodynamic rupture simulations

abstract:
  We study strain localization as an enhanced velocity weakening mechanism on
earthquake faults. Fault friction is modeled using Shear Transformation Zone
(STZ) Theory, a microscopic physical model for non-affine rearrangements in
granular fault gouge. STZ Theory is implemented in spring slider and dynamic
rupture models of faults. We compare dynamic shear localization to deformation
that is uniform throughout the gouge layer, and find that localized slip
enhances the velocity weakening of the gouge. Localized elastodynamic ruptures
have larger stress drops and higher peak slip rates than ruptures with
homogeneous strain.


title:
Constraints from Solar and Reactor Neutrinos on Unparticle Long-Range
  Forces

abstract:
  We have investigated the impact of long-range forces induced by unparticle
operators of scalar, vector and tensor nature coupled to fermions in the
interpretation of solar neutrinos and KamLAND data. If the unparticle couplings
to the neutrinos are mildly non-universal, such long-range forces will not
factorize out in the neutrino flavour evolution. As a consequence large
deviations from the observed standard matter-induced oscillation pattern for
solar neutrinos would be generated. In this case, severe limits can be set on
the infrared fix point scale, Lambda_u, and the new physics scale, M, as a
function of the ultraviolet (d_UV) and anomalous (d) dimension of the
unparticle operator. For a scalar unparticle, for instance, assuming the
non-universality of the lepton couplings to unparticles to be of the order of a
few per mil we find that, for d_UV=3 and d=1.1, M is constrained to be M >
O(10^9) TeV (M > O(10^10) TeV) if Lambda_u= 1 TeV (10 TeV). For given values of
Lambda_u and d, the corresponding bounds on M for vector [tensor] unparticles
are approximately 100 [3/Sqrt(Lambda_u/TeV)] times those for the scalar case.
Conversely, these results can be translated into severe constraints on
universality violation of the fermion couplings to unparticle operators with
scales which can be accessible at future colliders.


title: Luminosity Indicators in the Ultraviolet Spectra of Type Ia Supernovae

abstract:
  We present a complete sample of International Ultraviolet Explorer and Hubble
Space Telescope ultraviolet (UV) spectra of Type Ia supernovae (SNe Ia) through
2004. We measure the equivalent width (EW) and blueshifted velocity of the
minimum of the one strong UV feature, Fe II 3250. We also quantify the slope of
the near-UV spectra using a new parameter, the ``UV ratio.'' We find that the
velocity of the Fe II line does not correlate with light-curve shape, while the
EW shows distinct behavior for the slow and fast-declining objects. Using
precise Cepheid and surface brightness fluctuation distance measurements of 6
objects with UV spectra observed near maximum light (a total of 12 spectra), we
determine that the UV ratio at maximum light is highly correlated with SN Ia
luminosity. A larger sample of UV spectra is necessary to increase the
statistical certainty of these luminosity indicators and whether they can be
combined with light-curve shape to improve measured SN Ia distances.


title: GRB: magnetic fields, cosmic rays, and emission from first principles?

abstract:
  We describe a scenario for large-scale magnetic field generation and particle
acceleration in a collisionless collision of cold plasma clouds. A
first-principle (i.e. using particles) numerical simulation of this process
might be possible. Our scenario is essentially 3D. We argue that {\it
large-scale} magnetic fields are not generated in 2D, even in collisionless
plasma.
  We calculate and numerically simulate magnetic field generation by
relativistic collisionless Kelvin-Helmholtz instability in 2D. Collisionless
tangential discontinuity might be more important than collisionless shock,
because tangential discontinuity remains unstable even in the hydro limit, when
the shock stabilizes.


title: Non-Markovian Open Quantum Systems

abstract:
  We construct a non-Markovian canonical dynamical map that accounts for
systems correlated with the environment. The physical meaning of not completely
positive maps is studied to obtain a theory of non-Markovian quantum dynamics.
The relationship between inverse maps and correlations with the environment is
established. A generalized non-Markovian master equation is derived from the
canonical dynamical map that goes beyond the Kossakowski-Lindblad Markovian
master equation. Non-equilibrium quantum thermodynamics can be be studied
within this theory.


title: Light-like tachyon condensation in Open String Field Theory

abstract:
  We use open string field theory to study the dynamics of unstable branes in
the bosonic string theory, in the background of a generic linear dilaton. We
find a simple exact solution describing a dynamical interpolation between the
perturbative vacuum and the recently discovered nonperturbative tachyon vacuum.
In our solution, the open string tachyon increases exponentially along a null
direction, after which nonlinearities set in and cause the solution to
asymptote to a static state. In particular, the wild oscillations of the open
string fields which plague the time-like rolling tachyon solution are entirely
absent. Our model thus represents the first example proving that the true
tachyon vacuum of open string field theory can be realized as the endpoint of a
dynamical transition from the perturbative vacuum.


title:
The unusual thickness dependence of superconductivity in $\alpha$-MoGe
  thin films

abstract:
  Thin films of $\alpha$-MoGe show progressively reduced $T_{c}$'s as the
thickness is decreased below 30 nm and the sheet resistance exceeds 100
$\Omega/\Box$. We have performed far-infrared transmission and reflection
measurements for a set of $\alpha$-MoGe films to characterize this weakened
superconducting state. Our results show the presence of an energy gap with
ratio $2\Delta_0/k_BT_{c} = 3.8 \pm 0.1$ in all films studied, slightly higher
than the BCS value, even though the transition temperatures decrease
significantly as film thickness is reduced. The material properties follow
BCS-Eliashberg theory with a large residual scattering rate except that the
coherence peak seen in the optical scattering rate is found to be strongly
smeared out in the thinner superconducting samples. A peak in the optical mass
renormalization at $2\Delta_0$ is predicted and observed for the first time.


title: On Lagrangian fibrations by Jacobians I

abstract:
  Let Y->P^n be a flat family of integral Gorenstein curves, such that the
compactified relative Jacobian X=\bar{J}^d(Y/P^n) is a Lagrangian fibration. We
prove that the degree of the discriminant locus Delta in P^n is at least 4n+2,
and we prove that X is a Beauville-Mukai integrable system if the degree of
Delta is greater than 4n+20.


title: The Dolbeault complex with weights according to normal crossings

abstract:
  In this paper, we define a Dolbeault complex with weights according to normal
crossings, which is a useful tool for studying the d-bar-equation on singular
complex spaces by resolution of singularities (where normal crossings appear
naturally). The major difficulty is to prove that this complex is locally
exact. We do that by constructing a local d-bar-solution operator which
involves only Cauchy's Integral Formula (in one complex variable) and behaves
well for L^p-forms with weights according to normal crossings.


title: The d-bar-equation on homogeneous varieties with an isolated singularity

abstract:
  Let X be a regular irreducible variety in CP^{n-1}, Y the associated
homogeneous variety in C^n, and N the restriction of the universal bundle of
CP^{n-1} to X. In the present paper, we compute the obstructions to solving the
d-bar-equation in the L^p-sense on Y for 1<=p<=\infty in terms of cohomology
groups H^q(X,O(N^m)). That allows to identify obstructions explicitly if X is
specified more precisely, for example if it is equivalent to CP^1 or an
elliptic curve.


title: Infinite words containing squares at every position

abstract:
  Richomme asked the following question: what is the infimum of the real
numbers $\alpha$ > 2 such that there exists an infinite word that avoids
$\alpha$-powers but contains arbitrarily large squares beginning at every
position? We resolve this question in the case of a binary alphabet by showing
that the answer is $\alpha$ = 7/3.


title:
Multiple Avalanches Across the Metal-Insulator Transition of Vanadium
  Oxide Nano-scaled Junctions

abstract:
  The metal insulator transition of nano-scaled $VO_2$ devices is drastically
different from the smooth transport curves generally reported. The temperature
driven transition occurs through a series of resistance jumps ranging over 2
decades in amplitude, indicating that the transition is caused by avalanches.
We find a power law distribution of the jump amplitudes, demonstrating an
inherent property of the $VO_2$ films. We report a surprising relation between
jump amplitude and device size. A percolation model captures the general
transport behavior, but cannot account for the statistical behavior.


title:
The role of dipolar interactions for the determination of intrinsic
  switching field distributions

abstract:
  The $\Delta H(M, \Delta M)$ method and its ability to determine intrinsic
switching field distributions of perpendicular recording media are numerically
studied. It is found that the presence of dipolar interactions in the range of
typical recording media substantially enhances the reliability of the $\Delta
H(M,\Delta M)$ method. In addition, a strong correlation is observed between
the precision of this method and a self-consistency-check of the data sets,
which is based upon a simple redundancy measure. This suggests that the latter
can be utilized as an efficient criterion to decide if a complete data analysis
is warranted or not.


title: Stability and instability results in a model of Fermi acceleration

abstract:
  We consider the static wall approximation to the dynamics of a particle
bouncing on a periodically oscillating infinitely heavy plate while subject to
a potential force. We assume the case of a potential given by a power of the
particle's height and sinusoidal motions of the plate. We find that for powers
smaller than 1 the set of escaping orbits has full Hausdorff dimension for all
motions and obtain existence of elliptic island of period 2 for arbitrarily
high energies for a full-measure set of motions. Moreover we obtain conditions
on the potential to ensure that the total (Lebesgue) measure of elliptic
islands of period 2 is either finite or infinite.


title: Lie Algebraic Analysis and Control of Quantum Dynamics

abstract:
  In this paper, we show how to use the analysis of the Lie algebra associated
with a quantum mechanical system to study its dynamics and facilitate the
design of controls. We give algorithms to decompose the dynamics and describe
their application to the control of two coupled spin 1/2's.


title: Les Houches Lectures on Constructing String Vacua

abstract:
  These lectures give a detailed introduction to constructing and analyzing
string vacua suitable for phenomenological model building, with particular
emphasis on F-theory flux vacua. Topics include (1) general challenges and
overview of some proposed scenarios, (2) an extensive introduction to F-theory
and its relation to M-theory and perturbative IIB string theory, (3) F-theory
flux vacua and moduli stabilization scenarios, (4) a practical geometrical
toolkit for constructing string vacua from scratch, (5) statistics of flux
vacua, and (6) explicit models.


title: Secure Lossless Compression with Side Information

abstract:
  Secure data compression in the presence of side information at both a
legitimate receiver and an eavesdropper is explored. A noise-free, limited rate
link between the source and the receiver, whose output can be perfectly
observed by the eavesdropper, is assumed. As opposed to the wiretap channel
model, in which secure communication can be established by exploiting the noise
in the channel, here the existence of side information at the receiver is used.
Both coded and uncoded side information are considered. In the coded side
information scenario, inner and outer bounds on the compression-equivocation
rate region are given. In the uncoded side information scenario, the
availability of the legitimate receiver's and the eavesdropper's side
information at the encoder is considered, and the compression-equivocation rate
region is characterized for these cases. It is shown that the side information
at the encoder can increase the equivocation rate at the eavesdropper. Hence,
the side information at the encoder is shown to be useful in terms of security;
this is in contrast with the pure lossless data compression case where side
information at the encoder would not help.


title: Role of Single Qubit Decoherence Time in Adiabatic Quantum Computation

abstract:
  We have studied numerically the evolution of an adiabatic quantum computer in
the presence of a Markovian ohmic environment by considering Ising spin glass
systems with up to 20 qubits independently coupled to this environment via two
conjugate degrees of freedom. The required computation time is demonstrated to
be of the same order as that for an isolated system and is not limited by the
single-qubit decoherence time $T_2^*$, even when the minimum gap is much
smaller than the temperature and decoherence-induced level broadening. For
small minimum gap, the system can be described by an effective two-state model
coupled only longitudinally to environment.


title: The Gravitational Bohr Radius

abstract:
  The gravitational Bohr radius (GBR) characterizes the size of a hypothetical
ground state hydrogen atom wherein the binding interaction between its nucleus
and its electronic structure is purely gravitational. The conventional
calculation of the GBR, based on the standard Newtonian gravitational coupling
constant, yields an astronomical size for the "gravitational atom". On the
other hand, a discrete fractal cosmological paradigm asserts that the
gravitational coupling constant that applies within Atomic Scale systems is
roughly 38 orders of magnitude larger than the conventional gravitational
constant. According to calculations based on predictions of this discrete
fractal paradigm, the value of the GBR is actually on the order of 2 pi times
the standard Bohr radius. Implications of this revised gravitational Bohr
radius are discussed.


title: Electrodynamics of spin currents in superconductors

abstract:
  In recent work we formulated a new set of electrodynamic equations for
superconductors as an alternative to the conventional London equations,
compatible with the prediction of the theory of hole superconductivity that
superconductors expel negative charge from the interior towards the surface.
Charge expulsion results in a macroscopically inhomogeneous charge distribution
and an electric field in the interior, and because of this a spin current is
expected to exist. Furthermore, we have recently shown that a dynamical
explanation of the Meissner effect in superconductors leads to the prediction
that a spontaneous spin current exists near the surface of superconductors. In
this paper we extend the electrodynamic equations proposed earlier for the
charge density and charge current to describe also the space and time
dependence of the spin density and spin current. This allows us to determine
the magnitude of the expelled negative charge and interior electric field as
well as of the spin current in terms of other measurable properties of
superconductors. We also provide a 'geometric' interpretation of the difference
between type I and type II superconductors, discuss the relationship between
our model and Slater's seminal work on superconductivity, and discuss the
magnitude of the expected novel effects for elemental and other
superconductors.


title:
LensPerfect: Gravitational Lens Massmap Reconstructions Yielding Exact
  Reproduction of All Multiple Images

abstract:
  We present a new approach to gravitational lens massmap reconstruction. Our
massmap solutions perfectly reproduce the positions, fluxes, and shears of all
multiple images. And each massmap accurately recovers the underlying mass
distribution to a resolution limited by the number of multiple images detected.
We demonstrate our technique given a mock galaxy cluster similar to Abell 1689
which gravitationally lenses 19 mock background galaxies to produce 93 multiple
images. We also explore cases in which far fewer multiple images are observed,
such as four multiple images of a single galaxy. Massmap solutions are never
unique, and our method makes it possible to explore an extremely flexible range
of physical (and unphysical) solutions, all of which perfectly reproduce the
data given. Each reconfiguration of the source galaxies produces a new massmap
solution. An optimization routine is provided to find those source positions
(and redshifts, within uncertainties) which produce the "most physical" massmap
solution, according to a new figure of merit developed here. Our method imposes
no assumptions about the slope of the radial profile nor mass following light.
But unlike "non-parametric" grid-based methods, the number of free parameters
we solve for is only as many as the number of observable constraints (or
slightly greater if fluxes are constrained). For each set of source positions
and redshifts, massmap solutions are obtained "instantly" via direct matrix
inversion by smoothly interpolating the deflection field using a recently
developed mathematical technique. Our LensPerfect software is straightforward
and easy to use and is made publicly available via our website.


title:
The finiteness result for Khovanov homology and localization in monoidal
  categories

abstract:
  In the previous paper we constructed the local system of Khovanov complexes
on the Vassiliev space of knots and extended it to the singular locus. In this
paper we introduce the definition of the homology theory (local system) of
finite type and prove the first finiteness result: the Khovanov local system
restricted to the subcategory of knots of the crossing number at most n is the
theory of type less or equal to n. This result can be further generalized to
the categorification of Birman-Lin theorem.


title:
2.5 Dimensional Particle-in-Cell Simulations of Relativistic Plasma
  Collisions

abstract:
  We use electromagnetic Particle-in-Cell codes to investigate the two-stream
instability and Weibel instability when two beams of plasma collide head-on
relativistically. We compare the dissipation of kinetic energies in the two
cases. We also study the evolution of the resultant electron energy
distribution function produced by such dissipation.


title: Distributed Subgradient Methods and Quantization Effects

abstract:
  We consider a convex unconstrained optimization problem that arises in a
network of agents whose goal is to cooperatively optimize the sum of the
individual agent objective functions through local computations and
communications. For this problem, we use averaging algorithms to develop
distributed subgradient methods that can operate over a time-varying topology.
Our focus is on the convergence rate of these methods and the degradation in
performance when only quantized information is available. Based on our recent
results on the convergence time of distributed averaging algorithms, we derive
improved upper bounds on the convergence rate of the unquantized subgradient
method. We then propose a distributed subgradient method under the additional
constraint that agents can only store and communicate quantized information,
and we provide bounds on its convergence rate that highlight the dependence on
the number of quantization levels.


title: Spectral Flow, and the Spectrum of Multi-Center Solutions

abstract:
  We discuss "spectral flow" coordinate transformations that take
asymptotically four-dimensional solutions into other asymptotically
four-dimensional solutions. We find that spectral flow can relate smooth
three-charge solutions with a multi-center Taub-NUT base to solutions where one
or several Taub-NUT centers are replaced by two-charge supertubes, and vice
versa. We further show that multi-parameter spectral flows can map such
Taub-NUT centers to more singular centers that are either D2-D0 or pure
D0-brane sources. Since supertubes can depend on arbitrary functions, we
establish that the moduli space of smooth horizonless black hole microstate
solutions is classically of infinite dimension. We also use the physics of
supertubes to argue that some multi-center solutions that appear to be bound
states from a four-dimensional perspective are in fact not bound states when
considered from a five- or six-dimensional perspective.


title:
Resonance Clustering in Globally Coupled Electrochemical Oscillators
  with External Forcing

abstract:
  Experiments are carried out with a globally coupled, externally forced
population of limit-cycle electrochemical oscillators with an approximately
unimodal distribution of heterogeneities. Global coupling induces mutually
entrained (at frequency $\omega_{1}$) states; periodic forcing produces
forced-entrained ($\omega_{\mathrm{F}}$) states. As a result of the interaction
of mutual and forced entrainment, resonant cluster states occur with equal
spacing of frequencies that have discretized frequencies following a resonance
rule $\omega_{n}\cong n\omega_{1}-(n-1)\omega_{\mathrm{F}}$. Resonance
clustering requires an optimal, intermediate global coupling strength; at weak
coupling the clusters have smaller sizes and do not strictly follow the
resonance rule, while at strong coupling the population behaves similar to a
single, giant oscillator.


title:
Picard number of the generic fiber of an abelian fibered hyperkaehler
  manifold

abstract:
  We shall show that the Picard number of the generic fiber, in the sense of
scheme, of an abelian fibered hyperk\"ahler manifold over the projective space
is always one. We then give a few applications for the Mordell-Weil group. In
particular, by deforming O'Grady's 10-dimensional manifold, we construct an
abelian fibered hyperk\"ahler manifold of Mordell-Weil rank 20, which is the
maximum possible among all known ones.


title:
Cluster observations of the mid-altitude cusp under strong northward
  Interplanetary Magnetic Field

abstract:
  This paper has been withdrawn by the author since it has been accepted for
publishing in J. Geophys. Res. Please contact the American Geophysical Union
for the refereed article.


title: Serious Flaws in Korf et al.'s Analysis on Time Complexity of A*

abstract: This paper has been withdrawn.


title: Systems with the integer rounding property in normal monomial subrings

abstract:
  Let C be a clutter and let A be its incidence matrix. If the linear system
x>=0;xA<=1 has the integer rounding property, we give a description of the
canonical module and the a-invariant of certain normal subrings associated to
C. If the clutter is a connected graph, we describe when the aforementioned
linear system has the integer rounding property in combinatorial and algebraic
terms using graph theory and the theory of Rees algebras. As a consequence we
show that the extended Rees algebra of the edge ideal of a bipartite graph is
Gorenstein if and only if the graph is unmixed.


title:
Single-artificial-atom lasing using a voltage-biased superconducting
  charge qubit

abstract:
  We consider a system composed of a single artificial atom coupled to a cavity
mode. The artificial atom is biased such that the most dominant relaxation
process in the system takes the atom from its ground state to its excited
state, thus ensuring population inversion. A recent experimental manifestation
of this situation was achieved using a voltage-biased superconducting charge
qubit. Even under the condition of `inverted relaxation', lasing action can be
suppressed if the `relaxation' rate is larger than a certain threshold value.
Using simple transition-rate arguments and a semiclassical calculation, we
derive analytic expressions for the lasing suppression condition and the state
of the cavity in both the lasing and suppressed-lasing regimes. The results of
numerical calculations agree very well with the analytically derived results.
We start by analyzing a simplified two-level-atom model, and we then analyze a
three-level-atom model that should describe accurately the recently realized
superconducting artificial-atom laser.


title:
Optical properties of silicon carbide for astrophysical applications I.
  New laboratory infrared reflectance spectra and optical constants

abstract:
  Silicon Carbide (SiC) optical constants are fundamental inputs for radiative
transfer models of astrophysical dust environments. However, previously
published values contain errors and do not adequately represent the bulk
physical properties of the cubic (beta) SiC polytype usually found around
carbon stars. We provide new, uncompromised optical constants for beta- and
alpha-SiC derived from single-crystal reflectance spectra and investigate
quantitatively whether there is any difference between alpha- and beta-SiC that
can be seen in infrared spectra and optical functions.
  Previous optical constants for SiC do not reflect the true bulk properties,
and they are only valid for a narrow grain size range. The new optical
constants presented here will allow narrow constraints to be placed on the
grain size and shape distribution that dominate in astrophysical environments.
In addition, our calculated absorption coefficients are much higher than
laboratory measurements, which has an impact on the use of previous data to
constrain abundances of these dust grains.


title: Correlation effects in quasi one dimensional electron wires

abstract:
  We explore the role of electron correlation in quasi one dimensional quantum
wires as the range of the interaction potential is changed and their thickness
is varied by performing exact quantum Monte Carlo simulations at various
electronic densities. In the case of unscreened interactions with a long range
1/x tail there is a crossover from a liquid to a quasi Wigner crystal state as
the density decreases. When this interaction is screened, quasi long range
order is prevented from forming, although a significant correlation with 4 k_F
periodicity is still present at low densities. At even lower electron
concentration, exchange is suppressed and the spin-dependent interactions
become negligible, making the electrons behave like spinless fermions. We show
that this behavior is shared by the long range and screened interactions by
studying the spin and charge excitations of the system in both cases. Finally,
we study the effect of electron correlations in the double quantum wire
experiment [Steinberg et al., Phys. Rev. B 77, 113307 (2006)], by introducing
an accurate model for the screening in the experiment and explicitly including
the finite length of the system in our simulations. We find that decreasing the
electron density drives the system from a liquid to a state with quite strong 4
k_F correlations. This crossover takes place around $20 \mu m^{-1}$, the
density where the electron localization occurs in the experiment. The charge
and spin velocities are also in remarkable agreement with the experimental
findings in the proximity of the crossover. We argue that correlation effects
play an important role at the onset of the localization transition.


title: An Exceptional Algebraic Origin of the AdS/CFT Yangian Symmetry

abstract:
  In the su(2|2) spin chain motivated by the AdS/CFT correspondence, a novel
symmetry extending the superalgebra su(2|2) into u(2|2) was found. We pursue
the origin of this symmetry in the exceptional superalgebra d(2,1;epsilon),
which recovers su(2|2) when the parameter epsilon is taken to zero. Especially,
we rederive the Yangian symmetries of the AdS/CFT spin chain using the
exceptional superalgebra and find that the epsilon-correction corresponds to
the novel symmetry. Also, we reproduce the non-canonical classical r-matrix of
the AdS/CFT spin chain expressed with this symmetry from the canonical one of
the exceptional algebra.


title:
Reconstructing the cosmic density field with the distribution of dark
  matter halos

abstract:
  We develop a new method to reconstruct the cosmic density field from the
distribution of dark matter haloes above a certain mass threshold. Our
motivation is that well-defined samples of galaxy groups/clusters, which can be
used to represent the dark halo population, can now be selected from large
redshift surveys of galaxies, and our ultimate goal is to use such data to
reconstruct the cosmic density field in the local universe. Our reconstruction
method starts with a sample of dark matter haloes above a given mass threshold.
Each volume element in space is assigned to the domain of the nearest halo
according to a distance measure that is scaled by the virial radius of the
halo. The distribution of the mass in and around dark matter haloes of a given
mass is modelled using the cross-correlation function between dark matter
haloes and the mass distribution within their domains. We use N-body
cosmological simulations to show that the density profiles required in our
reconstruction scheme can be determined reliably from large cosmological
simulations, and that our method can reconstruct the density field accurately
using haloes with masses down to $\sim 10^{12}\msun$ (above which samples of
galaxy groups can be constructed from current large redshift surveys of
galaxies). Working in redshift space, we demonstrate that the redshift
distortions due to the peculiar velocities of haloes can be corrected in an
iterative way. We also describe some applications of our method.


title:
Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up
  Chemical Model

abstract:
  Gas-phase processes were long thought to be the key formation mechanisms for
complex organic molecules in star-forming regions. However, recent experimental
and theoretical evidence has cast doubt on the efficiency of such processes.
Grain-surface chemistry is frequently invoked as a solution, but until now
there have been no quantitative models taking into account both the high degree
of chemical complexity and the evolving physical conditions of star-forming
regions. Here, we introduce a new gas-grain chemical network, wherein a wide
array of complex species may be formed by reactions involving radicals. The
radicals we consider (H, OH, CO, HCO, CH3, CH3O, CH2OH, NH and NH2) are
produced primarily by cosmic ray-induced photodissociation of the granular ices
formed during the colder, earlier stages of evolution. The gradual warm-up of
the hot core is crucial to the formation of complex molecules, allowing the
more strongly-bound radicals to become mobile on grain surfaces. This type of
chemistry is capable of reproducing the high degree of complexity seen in Sgr
B2(N), and can explain the observed abundances and temperatures of a variety of
previously detected complex organic molecules, including structural isomers.
Many other complex species are predicted by this model, and several of these
species may be detectable in hot cores. Differences in the chemistry of high-
and low-mass star-formation are also addressed; greater chemical complexity is
expected where evolution timescales are longer.


title: Fermionic ground state at unitarity and Haldane Exclusion Statistics

abstract:
  We consider a few-particle system of trapped neutral fermionic atoms at
ultra-low temperatures, with the attractive interaction tuned to Feshbach
resonance. We calculate the energies and the spatial densities of the few-body
systems using a generalisation of the extended Thomas-Fermi (ETF) method, and
assuming the particles obey the Haldane-Wu fractional exclusion statistics
(FES) at unitarity. This method is different from the scaled ETF version given
by Chang and Bertsch (Phys. Rev. A76,021603(R) (2007)). Our semiclassical FES
results are consistent with the Monte-Carlo calculations of the above authors,
but can hardly be distinguished from their over all scaling of the ETF result
at unitarity.


title: Observation of simultaneous fast and slow light

abstract:
  We present a microresonator-based system capable of simultaneously producing
time-advanced and time-delayed pulses. The effect is based on the combination
of a sharp spectral feature with two orthogonally-polarized propagating
waveguide modes. We include an experimental proof-of-concept implementation
using a silica microsphere coupled to a tapered optical fiber and use a
time-domain picture to interpret the observed delays. We also discuss potential
applications for future all-optical networks.


title: Hsiao-Code Check Matrices and Recursively Balanced Matrices

abstract:
  The key step of generating the well-known Hsiao code is to construct a
{0,1}-check-matrix in which each column contains the same odd-number of 1's and
each row contains the same number of 1's or differs at most by one for the
number of 1's. We also require that no two columns are identical in the matrix.
The author solved this problem in 1986 by introducing a type of recursively
balanced matrices. However, since the paper was published in Chinese, the
solution for such an important problem was not known by international
researchers in coding theory. In this note, we focus on how to practically
generate the check matrix of Hsiao codes. We have modified the original
algorithm to be more efficient and effective. We have also corrected an error
in algorithm analysis presented in the earlier paper. The result shows that the
algorithm attained optimum in average cases if a divide-and-conquer technique
must be involved in the algorithm.


title:
On nonhomogeneous slip boundary conditions for 2D incompressible
  exterior fluid flows

abstract:
  The paper examines the issue of existence of solutions to the steady
Navier-Stokes equations in an exterior domain in $\mathbb{R}^2$. The system is
studied with nonhomogeneous slip boundary conditions. The main results proves
the existence of weak solutions for arbitrary data.


title: Optical squeezing of a mechanical oscillator by dispersive interaction

abstract:
  We consider a small partially reflecting vibrating mirror coupled
dispersively to a single optical mode of a high finesse cavity. We show this
arrangement can be used to implement quantum squeezing of the mechanically
oscillating mirror.


title: 22-Step Collisions for SHA-2

abstract:
  In this note, we provide the first 22-step collisions for SHA-256 and
SHA-512. Detailed technique of generating these collisions will be provided in
the next revision of this note.


title:
Non-Singular Assembly-mode Changing Motions for 3-RPR Parallel
  Manipulators

abstract:
  When moving from one arbitrary location at another, a parallel manipulator
may change its assembly-mode without crossing a singularity. Because the
non-singular change of assembly-mode cannot be simply detected, the actual
assembly-mode during motion is difficult to track. This paper proposes a global
explanatory approach to help better understand non-singular assembly-mode
changing motions for 3-RPR planar parallel manipulators. The approach consists
in fixing one of the actuated joints and analyzing the configuration-space as a
surface in a 3-dimensional space. Such a global description makes it possible
to display all possible non-singular assembly-mode changing trajectories.


title: A stochastic-Lagrangian particle system for the Navier-Stokes equations

abstract:
  This paper is based on a formulation of the Navier-Stokes equations developed
by P. Constantin and the first author (\texttt{arxiv:math.PR/0511067}, to
appear), where the velocity field of a viscous incompressible fluid is written
as the expected value of a stochastic process. In this paper, we take $N$
copies of the above process (each based on independent Wiener processes), and
replace the expected value with $\frac{1}{N}$ times the sum over these $N$
copies. (We remark that our formulation requires one to keep track of $N$
stochastic flows of diffeomorphisms, and not just the motion of $N$ particles.)
  We prove that in two dimensions, this system of interacting diffeomorphisms
has (time) global solutions with initial data in the space
$\holderspace{1}{\alpha}$ which consists of differentiable functions whose
first derivative is $\alpha$ H\"older continuous (see Section \ref{sGexist} for
the precise definition). Further, we show that as $N \to \infty$ the system
converges to the solution of Navier-Stokes equations on any finite interval
$[0,T]$. However for fixed $N$, we prove that this system retains roughly
$O(\frac{1}{N})$ times its original energy as $t \to \infty$. Hence the limit
$N \to \infty$ and $T\to \infty$ do not commute. For general flows, we only
provide a lower bound to this effect. In the special case of shear flows, we
compute the behaviour as $t \to \infty$ explicitly.


title: Radiative decays of the $(0^+,1^+)$ strange-bottom mesons

abstract:
  In this article, we assume that the $(0^+,1^+)$ strange-bottom mesons are the
conventional $b\bar{s}$ mesons, and calculate the electromagnetic coupling
constants $d$, $g_1$, $g_2$ and $g_3$ using the light-cone QCD sum rules. Then
we study the radiative decays $B_{s0}\to B_s^* \gamma$, $B_{s1}\to B_s \gamma$,
$B_{s1}\to B_s^* \gamma$ and $B_{s1}\to B_{s0} \gamma$, and observe that the
widths are rather narrow. We can search for the $(0^+,1^+)$ strange-bottom
mesons in the invariant $B_s \pi^0$ and $B^*_s \pi^0$ mass distributions in the
strong decays or in the invariant $B_s^*\gamma$ and $B_s\gamma$ mass
distributions in the radiative decays.


title: Magneto-Hydrodynamics of Population III Star Formation

abstract:
  Jet driving and fragmentation process in collapsing primordial cloud are
studied using three-dimensional MHD nested grid simulations. Starting from a
rotating magnetized spherical cloud with the number density of n=10^3 cm^-3, we
follow the evolution of the cloud up to the stellar density n=10^22 cm^-3. We
calculate 36 models parameterizing the initial magnetic and rotational energies
(\gamma_0, \beta_0). In the collapsing primordial clouds, the cloud evolutions
are characterized by the ratio of the initial rotational to magnetic energy,
\gamma_0/\beta_0. The Lorentz force significantly affects the cloud evolution
when \gamma_0 > \beta_0, while the centrifugal force is more dominant than the
Lorentz force when \beta_0 > \gamma_0. When the cloud rotates rapidly with
angular velocity of \Omega_0 > 10^-17 (n/10^3 cm^-3)^2/3 s^-1 and \beta_0 >
\gamma_0, fragmentation occurs before the protostar is formed, but no jet
appears after the protostar formation. On the other hand, a strong jet appears
after the protostar formation without fragmentation when the initial cloud has
the magnetic field of B_0 > 10^-9 (n/10^3 cm^-3)^2/3 G and \gamma_0 > \beta_0.
Our results indicate that proto-Population III stars frequently show
fragmentation and protostellar jet. Population III stars are therefore born as
binary or multiple stellar systems, and they can drive strong jets, which
disturb the interstellar medium significantly, as well as in the present-day
star formation, and thus they may induce the formation of next generation
stars.


title: Parameter Collapse due to the Zeros in the Inverse Condition

abstract:
  Helton, Lasserre, and Putinar (2008, Ann. Probability; arXiv:math/0702314)
expose the relationship between three properties of a measure: the conditional
triangularity property of the associated orthogonal polynomials, the zeros in
the inverse condition of the truncated moment matrix, and conditional
independence. The purpose of this article is to provide examples of parameter
collapse to product structure given that the zeros in the inverse condition
holds up to some degree d. Specifically, start with a parameterized family of
probability density functions; require that the zeros in the inverse condition
up to degree d holds; and validate that imposing this restriction on the
parameterized family results in a measure with product structure, or at least
that conditional independence holds. Algorithms related to parameter collapse
are supplied, including the computation of the zeros in the inverse condition
up to degree d.


title:
Hybrid skew scattering regime of the anomalous Hall effect in Rashba
  systems: unifying Keldysh, Boltzmann, and Kubo formalisms

abstract:
  We present the analytical description of the anomalous Hall effect (AHE) in a
2DEG ferromagnet within the Keldysh formalism. These results unify all three
linear response approaches to anomalous Hall transport and close a long
standing debate. We are able to identify a new extrinsic AHE regime dominated
by a hybrid skew scattering mechanism. This new contribution is inversely
proportional to the impurity concentration, resembling the normal skew
scattering, {\em but} independent of the impurity-strength, resembling the
side-jump mechanism. Within the Kubo formalism this regime is captured by
higher order diagrams which, although weak, dominate when both subbands are
occupied; this regime can be detected by variable remote doping experiments
that we describe.


title: Linear programming bounds for unitary space time codes

abstract:
  The linear programming method is applied to the space $\U_n(\C)$ of unitary
matrices in order to obtain bounds for codes relative to the diversity sum and
the diversity product. Theoretical and numerical results improving previously
known bounds are derived.


title:
Calculation of Spectral Darkening and Visibility Functions for Solar
  Oscillations

abstract:
  Calculations of spectral darkening and visibility functions for the
brightness oscillations of the Sun resulting from global solar oscillations are
presented. This has been done for a broad range of the visible and infrared
continuum spectrum. The procedure for the calculations of these functions
includes the numerical computation of depth-dependent derivatives of the
opacity caused by p modes in the photosphere. A radiative-transport code was
used for this purpose to get the disturbances of the opacities from temperature
and density fluctuations. The visibility and darkening functions are obtained
for adiabatic oscillations under the assumption that the temperature
disturbances are proportional to the undisturbed temperature of the
photosphere. The latter assumption is the only way to explore any opacity
effects since the eigenfunctions of p-mode oscillations have not been obtained
so far. This investigation reveals that opacity effects have to be taken into
account because they dominate the violet and infrared part of the spectrum.
Because of this dominance, the visibility functions are negative for those
parts of the spectrum. Furthermore, the darkening functions show a
wavelength-dependent change of sign for some wavelengths owing to these opacity
effects. However, the visibility and darkening functions under the assumptions
used contradict the observations of global p-mode oscillations, but it is
beyond doubt that the opacity effects influence the brightness fluctuations of
the Sun resulting from global oscillations.


title: Atomic current in optical lattices: Esaki-Tsu equation revisited

abstract:
  The paper discusses the master equation approach to derivation of the
Esaki-Tsu equation for drift current. It is shown that the relaxation term in
the master equation can be identified by measuring the velocity distribution of
the carriers. We also show that the standard form of the relaxation term, used
earlier to derive Esaki-Tsu equation, predicts unphysical velocity distribution
and suggest a more elaborated relaxation term, which is argued to correctly
capture the effect of bosonic bath in experiments on atomic current in optical
lattices.


title:
Energy-Dependent Electron-Electron Scattering and Spin Dynamics in a Two
  Dimensional Electron Gas

abstract:
  Measurements of spin dynamics of electrons in a degenerate two dimensional
electron gas, where the Dyakonov-Perel mechanism is dominant, have been used to
investigate the electron scattering time (tp*) as a function of energy near the
Fermi energy. Close to the Fermi energy the spin evolution is oscillatory,
indicating a quasi-collision-free regime of spin dynamics. As the energy is
increased a transition to exponential, collision-dominated, spin decay occurs.
The frequency and the value of tp* are extracted using a Monte Carlo simulation
method. At the Fermi energy tp* is very close to the ensemble momentum
relaxation time (tp) obtained from the electron mobility. For higher energies
tp* falls quadratically, consistent with theoretical expectations for the onset
of electron-electron scattering which is inhibited by the Pauli principle at
the Fermi energy.


title:
Probing the topcolor-assisted technicolor model via the single t-quark
  production at Hadron colliders

abstract:
  In this paper, we systematically study the contribution of the TC2 model to
the single t-quark production at the Hadron colliders, specially at the LHC.
The TC2 model can contribute to the cross section of the single t-quark
production in two different ways. First, the existence of the top-pions and
top-higgs can modify the $Wtb$ coupling via their loop contributions, and such
modification can cause the correction to the cross sections of all three
production modes. Our study shows that this kind of correction is negative and
very small in all cases. Thus it is difficult to observe such correction even
at the LHC. On the other hand, there exist the tree-level FC couplings in the
TC2 model which can also contribute to the cross sections of the $tq$ and
$t\bar{b}$ production processes. The resonant effect can greatly enhance the
cross sections of the $tq$ and $t\bar{b}$ productions. The first evidence of
the single t-quark production has been reported by the $D0$ collaboration and
the measured cross section for the single t-quark production of
$\sigma(p\bar{p}\to tb+X,tqb+X)$ is compatible at the 10% level with the
standard model prediction. Because the light top-pion can make great
contribution to the $t\bar{b}$ production, the top-pion mass should be very
large in order to make the predicted cross section in the TC2 model be
consistent with the Tevatron experiments. More detailed information about the
top-pion mass and the FC couplings in the TC2 model should be obtained with the
running of the LHC.


title:
Linear optical scheme to demonstrate genuine multipartite entanglement
  for single-particle W states

abstract:
  We consider the method of entanglement witness operator to verify genuine
multipartite entanglement for single-particle W states involving N parties. In
particular, linear optical schemes using photo detectors and beam splitters are
proposed to implement two different types of witness operator in experiment.
The first scheme that requires only a single measurement setting is shown to
detect genuine multipartite entanglement for the overall efficiency beyond
1-1/N. On the other hand, the second scheme with N+1 measurement settings
achieves success at a significantly lowered efficiency than 1-1/N.


title:
Armchair graphene nanoribbons: Electronic structure and electric field
  modulation

abstract:
  We report electronic structure and electric field modulation calculations in
the width direction for armchair graphene nanoribbons (acGNRs) using a
semi-empirical extended Huckel theory. Important band structure parameters are
computed, e.g. effectives masses, velocities and bandgaps. For the three types
of acGNRs, the pz orbital tight-binding parameters are extracted if feasible.
Furthermore, the effect of electric field in the width direction on acGNRs
dispersion is explored. It is shown that for the two types of semiconducting
acGNRs, an external electric field can reduce the bandgap to a few meV with
different quantitative behavior.


title: Source of CP Violation for Baryon Asymmetry of the Universe

abstract:
  The baryon asymmetry of the Universe requires CP violation, but the Standard
Model falls short by a factor of $10^{-10}$ or more. Starting from a clue at
the $B$ factories, we point out that the large Yukawa couplings of the
sequential fourth generation $t^\prime$ and $b^\prime$ quarks can provide
enhancement by a factor of over $10^{13}$, making the 2-3-4 generation quark
sector a viable source of CP violation for the baryon asymmetry of the
Universe. With recent hints of large $\sin2\Phi_{B_s}$ in $B_s^0$-$\bar B_s^0$
mixing from the Tevatron, the ultimate test would be to discover the $t^\prime$
and $b^\prime$ quarks at the Large Hadron Collider.


title: A new class of transport distances

abstract:
  We introduce a new class of distances between nonnegative Radon measures in
Euclidean spaces. They are modeled on the dynamical characterization of the
Kantorovich-Rubinstein-Wasserstein distances proposed by Benamou-Brenier and
provide a wide family interpolating between the Wasserstein and the homogeneous
(dual) Sobolev distances.
  From the point of view of optimal transport theory, these distances minimize
a dynamical cost to move a given initial distribution of mass to a final
configuration. An important difference with the classical setting in mass
transport theory is that the cost not only depends on the velocity of the
moving particles but also on the densities of the intermediate configurations
with respect to a given reference measure.
  We study the topological and geometric properties of these new distances,
comparing them with the notion of weak convergence of measures and the well
established Kantorovich-Rubinstein-Wasserstein theory. An example of possible
applications to the geometric theory of gradient flows is also given.


title: Current- and field-driven magnetic antivortices

abstract:
  Antivortices in ferromagnetic thin-film elements are in-plane magnetization
configurations with a core pointing perpendicular to the plane. By using
micromagnetic simulations, we find that magnetic antivortices gyrate on
elliptical orbits similar to magnetic vortices when they are excited by
alternating magnetic fields or by spin-polarized currents. The phase between
high-frequency excitation and antivortex gyration is investigated. In case of
excitation by spin-polarized currents the phase is determined by the
polarization of the antivortex, while for excitation by magnetic fields the
phase depends on the polarization as well as on the in-plane magnetization.
Simultaneous excitation by a current and a magnetic field can lead to a maximum
enhancement or to an entire suppression of the amplitude of the core gyration,
depending on the angle between excitation and in-plane magnetization. This
variation of the amplitude can be used to experimentally distinguish between
spin-torque and Oersted-field driven motion of an antivortex core.


title: On the Hard Lefschetz property of stringy Hodge numbers

abstract:
  For projective varieties with a certain class of 'mild' isolated
singularities and for projective threefolds with arbitrary Gorenstein canonical
singularities, we show that the stringy Hodge numbers satisfy the Hard
Lefschetz property. This result fits nicely with a 6-dimensional counterexample
of Mustata and Payne for the Hard Lefschetz property for stringy Hodge numbers
in general. We also give such an example, ours is a hypersurface singularity.


title:
Spin structure factors and valence-bond-solid states of the trimerized
  Heisenberg chains in a magnetic field

abstract:
  By means of the density matrix renormalization group (DMRG) method, the
static spin structure factors and the magnetization plateaus of the trimerized
Heisenberg ferromagnet-ferromagnet-antiferromagnet and
antiferromagnet-antiferromagnet-ferromagnet spin chains in the presence of a
magnetic field are elaborately studied. It is found that in the plateau states,
the static structure factor with three peaks does not vary with the external
magnetic field as well as the exchange couplings; the spin correlation function
behaves as a perfect sequence and has a simple relation with the magnetization
per site. An approximate wave function for the plateau states is proposed, and
a picture based on the valence-bond-solid states is presented in order to
understand the origin and the total number of the magnetization plateaus, which
are shown to be in agreement with the DMRG results.


title: Global Warming: the Sacrificial Temptation

abstract:
  The claimed unanimity of the scientific community about the human culpability
for global warming is questioned. Up today there exists no scientific proof of
human culpability. It is not the number of authors of a paper, which validates
its scientific content. The use of probability to assert the degree of
certainty with respect the global warming problem is shown to be misleading.
The debate about global warming has taken on emotional tones driven by passion
and irrationality while it should be a scientific debate. The degree of
hostility used to mull any dissonance voice demonstrates that the current
debate has acquired a quasi-religious nature. Scientists are behaving as
priests in their will "to save the planet". We are facing a dangerous social
phenomenon, which must be addressed from the social point of view. The current
unanimity of citizens, scientists, journalists, intellectuals and politicians
is intrinsically worrying. The calls to sacrifice our way of life to calm down
the upset nature is an emotional ancestral reminiscence of archaic fears, which
should be analyzed as such.


title:
Partial Observations, Einstein Locality and Bell Inequalities in
  Quantized Detector Networks

abstract:
  Quantized detector networks (QDN) deals with quantum information exchange
between observers and their apparatus rather than with systems under
observation. Partial observations in QDN involve subsets of the elementary
signal detectors which constitute an apparatus. We use them to prove that QDN
is consistent with Einstein locality and violations of Bell-type inequalities.


title: Geodesic multiplication as a tool for classical and quantum gravity

abstract:
  Algebraic systems called the local geodesic loops and their tangent Akivis
algebras are considered. Their possible role in theory of gravity is
considered. Quantum conditions for the infinitesimal quantum events are
proposed.


title: Deep meridional circulation below the solar convective envelope

abstract:
  With reasonable assumptions and approximations, we compute the velocity of
the meridional flow $U$ in the convective envelope by modified Chandrasekhar's
(1956) MHD equations. The analytical solution of such a modified equation is
found to be $U(x,\mu) = \sum_{n=0}^\infty \bigl[u1_n x^n + u2_n
x^{-(n+3)}\bigr] C_n^{3/2}(\mu)$, where $x$ is non-dimensional radius, $\mu =
cos{\vartheta}$, ${\vartheta}$ is the co-latitude, $C_n^{3/2} {(\mu)}$ are the
Gegenbaur polynomials of order 3/2, $u1_n$ and $u2_n$ are the unknown
constants. The results show that meridional velocity flow from the surface
appears to penetrates deep below base of the convective envelope and at outer
part of the radiative zone. With such a deep flow velocity below the convective
envelope and a very high density stratification in the outer part of the
radiative zone with likely existence of a strong ($\sim$ $10^{4}$ G) toroidal
magnetic field structure, the velocity of transport of meridional flow is
considerably reduced. Hence, it is very unlikely that the return flow will
reach the surface (with a period of solar cycle) as required by some of the
flux transport dynamo models. On the other hand, deep meridional flow is
required for burning of Lithium at outer part of the radiative zone supporting
the observed Lithium deficiency at the surface.


title: How to Find a Hidden World at the Large Hadron Collider

abstract:
  I discuss how the Large Hadron Collider era should broaden our view of
particle physics research, and apply this thinking to the case of Hidden
Worlds. I focus on one of the simplest representative cases of a Hidden World,
and detail the rich implications it has for LHC physics, including universal
suppression of Higgs boson production, trans-TeV heavy Higgs boson signatures,
heavy-to-light Higgs boson decays, weakly coupled exotic gauge bosons, and
Higgs boson decays to four fermions via light exotic gauge bosons. Some
signatures may be accessible in the very early stages of collider operation,
whereas others motivate a later high-lumonosity upgrade.


title: Moments of Two-Variable Functions and the Uniqueness of Graph Limits

abstract:
  For a symmetric bounded measurable function W on [0,1]^2, "moments" of W can
be defined as values t(F,W) indexed by simple graphs. We prove that every such
function is determined by its moments up to a measure preserving transformation
of the variables. This implies that the limit of a convergent dense graph
sequence is unique up to measure preserving transformation.


title: The shortest game of Chinese Checkers and related problems

abstract:
  In 1979, David Fabian found a complete game of two-person Chinese Checkers in
30 moves (15 by each player) [Martin Gardner, Penrose Tiles to Trapdoor
Ciphers, MAA, 1997]. This solution requires that the two players cooperate to
generate a win as quickly as possible for one of them. We show, using
computational search techniques, that no shorter game is possible. We also
consider a solitaire version of Chinese Checkers where one player attempts to
move her pieces across the board in as few moves as possible. In 1971, Octave
Levenspiel found a solution in 27 moves [Ibid.]; we demonstrate that no shorter
solution exists. To show optimality, we employ a variant of A* search, as well
as bidirectional search.


title:
The Impact of Stochastic Primordial Magnetic Fields on the Scalar
  Contribution to Cosmic Microwave Background Anisotropies

abstract:
  We study the impact of a stochastic background of primordial magnetic fields
on the scalar contribution of CMB anisotropies and on the matter power
spectrum. We give the correct initial conditions for cosmological perturbations
and the exact expressions for the energy density and Lorentz force associated
to the stochastic background of primordial magnetic fields, given a power-law
for their spectra cut at a damping scale. The dependence of the CMB temperature
and polarization spectra on the relevant parameters of the primordial magnetic
fields is illustrated.


title: Entropies of complex networks with hierarchically constrained topologies

abstract:
  The entropy of a hierarchical network topology in an ensemble of sparse
random networks with "hidden variables" associated to its nodes, is the
log-likelihood that a given network topology is present in the chosen
ensemble.We obtain a general formula for this entropy,which has a clear simple
interpretation in some simple limiting cases. The results provide new keys with
which to solve the general problem of "fitting" a given network with an
appropriate ensemble of random networks.


title: Testing properties of graphs and functions

abstract:
  We define an analytic version of the graph property testing problem, which
can be formulated as studying an unknown 2-variable symmetric function through
sampling from its domain and studying the random graph obtained when using the
function values as edge probabilities. We give a characterization of properties
testable this way, and extend a number of results about ``large graphs'' to
this setting. These results can be applied to the original graph-theoretic
property testing.


title:
Bergman approximations of harmonic maps into the space of Kahler metrics
  on toric varieties

abstract:
  We generalize the results of Song-Zelditch on geodesics in spaces of Kahler
metrics on toric varieties to harmonic maps of any compact Riemannian manifold
with boundary into the space of Kahler metrics on a toric variety. We show that
the harmonic map equation can always be solved and that such maps may be
approximated in the C^2 topology by harmonic maps into the spaces of Bergman
metrics. In particular, WZW maps, or equivalently solutions of a homogeneous
Monge-Ampere equation on the product of the manifold with a Riemann surface
with S^1 boundary admit such approximations. We also show that the
Eells-Sampson flow on the space of Kahler potentials is transformed to the
usual heat flow on the space of symplectic potentials under the Legendre
transform.


title: The Three Gap Theorem and Riemannian Geometry

abstract:
  The classical Three Gap Theorem asserts that for a natural number n and a
real number p, there are at most three distinct distances between consecutive
elements in the subset of [0,1) consisting of the reductions modulo 1 of the
first n multiples of p. Regarding it as a statement about rotations of the
circle, we find results in a similar spirit pertaining to isometries of compact
Riemannian manifolds and the distribution of points along their geodesics.


title:
Numerical renormalization group calculation of near-gap peaks in
  spectral functions of the Anderson model with superconducting leads

abstract:
  We use the numerical renormalization group method (NRG) to investigate a
single-impurity Anderson model with a coupling of the impurity to a
superconducting host. Analysis of the energy flow shows, in contrast to
previous belief, that NRG iterations can be performed up to a large number of
sites, corresponding to energy differences far below the superconducting gap.
This allows us to calculate the impurity spectral function very accurately for
frequencies near the gap edge, and to resolve, in a certain parameter regime,
sharp peaks in the spectral function close to the gap edge.


title: Contact surgeries and the transverse invariant in knot Floer homology

abstract:
  We study naturality properties of the transverse invariant in knot Floer
homology under contact (+1)-surgery. This can be used as a calculational tool
for the transverse invariant. As a consequence, we show that the
Eliashberg-Chekanov twist knots E_n are not transversely simple for n odd and
n>3.


title: Geometry and Rank of Fibered Hyperbolic 3-Manifolds

abstract:
  Assume that M is a closed hyperbolic 3-manifold fibering over the circle with
fiber a closed orientable surface of genus g. We show that if M has large
diameter and its injectivity radius is bounded below, then the rank of the
fundamental group of M is 2g+1.


title: Thermocapillary fluid and adiabatic waves near the critical point

abstract:
  Isothermal interfacial zones are investigated starting from a local energy
which can be considered as the sum of two terms: one corresponding to a medium
with a uniform composition equal to the local one and a second one associated
with the non-uniformity of the fluid. In an extended van der Waals theory, the
volume internal energy is proposed with a gradient expansion depending not only
on the gradient of density but also on the gradient of entropy. We obtain the
equation of conservative motions for non-homogeneous fluids near its critical
point. For such a medium, it is not possible to obtain shock waves. The waves
are tangential to the interface and the wave celerity is expressed depending on
thermodynamic conditions at the critical point.


title: Molecular fingerprinting with femtosecond lasers

abstract:
  Molecular fingerprinting through absorption spectroscopy is a powerful
analytical method. Wide spectral ranges are explored with Doppler-limited
resolution. Fast data acquisition, accurate measurements of frequency,
intensity, and line shape; time-resolved, selective spectra are achieved with
excellent sensitivities. However, presently spectrometers are unable to provide
all these features at once.


title: Screening in two-dimensional foams

abstract:
  Using the Surface Evolver software, we perform numerical simulations of
point-like deformations in a two-dimensional foam. We study perturbations which
are infinitesimal or finite, isotropic or anisotropic, and we either conserve
or do not conserve the number of bubbles. We measure the displacement fields
around the perturbation. Changes in pressure decrease exponentially with the
distance to perturbation, indicating a screening over a few bubble diameters.


title: Magnetism of Ru and Rh thin films on Ag(001) substrate

abstract:
  In a very recent x-ray magnetic circular dichroism experiment concerning with
Ru and Rh impurities and metal films on Ag(001) substrate, no local magnetic
momen ts were displayed in direct contradiction with previous theoretical
works. It is thought that there can be three main reasons for this
inconsistency: relaxation, alloying and many-body effects. Some of the
above-mentioned systems are studie d by using a first-principles method in
which relaxation and alloying are taken into account, even so magnetism is
still obtained. For low-coverage systems, hig h magnetic moments in both Ru
($\sim$ 2.49 $\mu_{B}$) and Rh ($\sim$ 2.00 $\mu_{B}$) are obtained. Naturally,
as the coverage is increased the magnetic moments are approached to zero. Also,
it is noticed that the relaxation distances are in creased by magnetism, which
in turn is decreased by alloying. The behavior of th e magnetic properties is
explained in terms of Stoner model.


title: Two paradigms for topological quantum computation

abstract:
  We present two paradigms relating algebraic, topological and quantum
computational statistics for the topological model for quantum computation. In
particular we suggest correspondences between the computational power of
topological quantum computers, computational complexity of link invariants and
images of braid group representations. While at least parts of these paradigms
are well-known to experts, we provide supporting evidence for them in terms of
recent results. We give a fairly comprehensive list of known examples and
formulate two conjectures that would further support the paradigms.


title:
Conformal quantum space $SU(2,2)\simeq O(2,4)$ with Poincare group of
  motion

abstract:
  It is shown that algebra of quantum space of the title of the present paper
may be realized on usual unphysical Minkowskii one. Equations of field theory
and there solutions are discussed. Solution equations of particle motion are
obtained in implicit form from the classical ones.


title:
On approximation of continuous functions by entire functions on subsets
  of the real line

abstract:
  We generalize the classical Bernstein theorem concerning the constructive
description of classes of functions uniformly continuous on the real line. The
approximation of continuous bounded functions by entire functions of
exponential type on unbounded closed proper subsets of the real line is
studded.


title: Chance and necessity in chromosomal gene distributions

abstract:
  By analyzing the spacing of genes on chromosomes, we find that
transcriptional and RNA-processing regulatory sequences outside coding regions
leave footprints on the distribution of intergenic distances. Using analogies
between genes on chromosomes and one-dimensional gases, we constructed a
statistical null model. We have used this to estimate typical upstream and
downstream regulatory sequence sizes in various species. Deviations from this
model reveal bi-directional transcriptional regulatory regions in S. cerevisiae
and bi-directional terminators in E. coli.


title: Dilepton production from a viscous QGP

abstract:
  This work calculates the first correction to the leading order q\={q}
dilepton production rates due to shear viscosity in an expanding gas. The
modified rates are integrated over the space-time history of a viscous
hydrodynamic simulation of RHIC collisions. The net result is a {\em hardening}
of $q_\perp$ spectrum with the magnitude of the correction increasing with
invariant mass. We argue that a thermal description is reliable for invariant
masses less than $M_{max}\approx(2\tau_0 T_0^2)/(\eta/s)$. For reasonable
values of the shear viscosity and thermalization time $M_{max}\approx 4.5$ GeV.
Finally, the early emission from a viscous medium is compared to emission from
a longitudinally free streaming plasma. Qualitative differences in $q_\perp$
spectrum are seen which could be used to extract information on the
thermalization time, viscosity to entropy ratio and possibly the thermalization
mechanism in heavy-ion collisions.


title: Kondo effect in single-molecule magnet transistors

abstract:
  We present a careful and thorough microscopic derivation of the Kondo
Hamiltonian for single-molecule magnets (SMMs) transistors. When the molecule
is strongly coupled to metallic leads, we show that by applying a transverse
magnetic field it is possible to topologically induce or quench the Kondo
effect in the conductance of a SMM with either an integer or a half-integer
spin S>1/2. This topological Kondo effect is due to the Berry phase
interference between multiple quantum tunneling paths of the spin. We calculate
the renormalized Berry phase oscillations of the two Kondo peaks as a function
of the transverse magnetic field by means of the poor man's scaling. In
particular, we show that the Kondo exchange interaction between itinerant
electrons in the leads and the SMM pseudo spin 1/2 depends crucially on the SMM
spin selection rules for the addition and subtraction of an electron and can
range from antiferromagnetic to ferromagnetic. We illustrate our findings with
the SMM Ni4, which we propose as a possible candidate for the experimental
observation of the conductance oscillations.


title: Nonclassicality without entanglement enables bit commitment

abstract:
  We investigate the existence of secure bit commitment protocols in the convex
framework for probabilistic theories. The framework makes only minimal
assumptions, and can be used to formalize quantum theory, classical probability
theory, and a host of other possibilities. We prove that in all such theories
that are locally non-classical but do not have entanglement, there exists a bit
commitment protocol that is exponentially secure in the number of systems used.


title: Ultraviolet Light Curves of Supernovae with Swift Uvot

abstract:
  We present ultravioliet (UV) observations of supernovae (SNe) obtained with
the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is
the largest sample of UV light curves from any single instrument and covers all
major SN types and most subtypes. The UV light curves of SNe Ia are fairly
homogenous while SNe Ib/c and IIP show more variety in their light curve
shapes. The UV-optical colors clearly differentiate SNe Ia and IIP,
particularly at early times. The color evolution of SNe IIP, however, makes
their colors similar to SNe Ia at about 20 days after explosion. SNe Ib/c are
shown to have varied UV-optical colors. The use of UV colors to help type SNe
will be important for high redshift SNe discovered in optical observations.
These data can be added to ground based optical and near infrared data to
create bolometric light curves of individual objects and as checks on generic
bolometric corrections used in the absence of UV data. This sample can also be
compared with rest-frame UV observations of high redshift SNe observed at
optical wavelengths.


title: Diffraction of stochastic point sets: Explicitly computable examples

abstract:
  Stochastic point processes relevant to the theory of long-range aperiodic
order are considered that display diffraction spectra of mixed type, with
special emphasis on explicitly computable cases together with a unified
approach of reasonable generality. The latter is based on the classical theory
of point processes and the Palm distribution. Several pairs of autocorrelation
and diffraction measures are discussed which show a duality structure analogous
to that of the Poisson summation formula for lattice Dirac combs.


title:
Ab initio supercell calculations on nitrogen-vacancy center in diamond:
  its electronic structure and hyperfine tensors

abstract:
  The nitrogen-vacancy center in diamond is a promising candidate for realizing
the spin qubits concept in quantum information. Even though this defect is
known for a long time, its electronic structure and other properties have not
yet been explored in detail. We study the properties of the nitrogen-vacancy
center in diamond through density functional theory within the local spin
density approximation, using supercell calculations. While this theory is
strictly applicable for ground state properties, we are able to give an
estimate for the energy sequence of the excited states of this defect. We also
calculate the hyperfine tensors in the ground state. The results clearly show
that: (i) the spin density and the appropriate hyperfine constants are spread
along a plane and unevenly distributed around the core of the defect; (ii) the
measurable hyperfine constants can be found within about 7 A from the vacancy
site. These results have important implications on the decoherence of the
electron spin which is crucial in realizing the spin qubits in diamond.


title: On the two dimensional Bilinear Hilbert Transform

abstract:
  We investigate the Bilinear Hilbert Transform in the plane and the pointwise
convergence of bilinear averages in Ergodic theory, arising from $\Z^2$
actions. Our techniques combine novel one and a half dimensional phase-space
analysis with more standard one dimensional theory.


title: Symmetries and the Riemann Hypothesis

abstract:
  Associated to classical semi-simple groups and their maximal parabolics are
genuine zeta functions. Naturally related to Riemann's zeta and governed by
symmetries, including that of Weyl, these zetas are expected to satisfy the
Riemann hypothesis.


title: Repeat distributions from unequal crossovers

abstract:
  It is a well-known fact that genetic sequences may contain sections with
repeated units, called repeats, that differ in length over a population, with a
length distribution of geometric type. A simple class of recombination models
with single crossovers is analysed that result in equilibrium distributions of
this type. Due to the nonlinear and infinite-dimensional nature of these
models, their analysis requires some nontrivial tools from measure theory and
functional analysis, which makes them interesting also from a mathematical
point of view. In particular, they can be viewed as quadratic, hence nonlinear,
analogues of Markov chains.


title: Taming Deeply Virtual Compton Scattering

abstract:
  We study recent Deeply Virtual Compton scattering (DVCS) data within a dual
parameterization of the Generalized Parton Distributions (GPDs). This
parameterization allows to quantify the maximum amount of information, that can
be extracted from DVCS data, in a ``quintessence'' function. We present a
``zero step'' model for the latter solely based on the forward quark density,
providing a parameter free prediction for the imaginary part of the DVCS
amplitude. It is shown that the bulk effect of the $e p \to e p \gamma$ beam
helicity asymmetry can be understood within such a model.


title: Constraining the Earliest Circumstellar Disks and their Envelopes

abstract:
  Using interferometric data from BIMA observations, combined with detailed
modeling in Fourier space of the physical structures predicted by models, we
constrain the circumstellar envelope parameters for four Class 0 young stellar
objects, as well as their embedded circumstellar disks. The envelopes of these
objects are still undergoing collapse, and theoretical collapse models can be
compared to the observations. Since it has been suggested in a previous study
that both the Larson-Penston and Shu similarity solutions underestimate the age
of the system, we adopt Tassis & Mouschovias' model of the collapse process,
which includes all relevant magnetic fields effects. The results of the model
fitting show a good consistency between theory and data; furthermore, no age
problem exists since the Tassis & Mouschovias' model is age independent for the
first 255 kyr. Although the majority of the continuum dust emission arises from
the circumstellar envelopes, these objects have well known outflows, which
suggest the presence of circumstellar disks. At the highest resolution, most of
the large-scale envelope emission is resolved out by interferometry, but the
small-scale residual emission remains, making it difficult to observe only the
compact disk component. By modeling the emission of the envelope and
subtracting it from the total emission, we constrain the disk masses in our
four systems to be comparable to or smaller than the typical disk masses for T
Tauri systems.


title:
Composition Profiles within Al3Li and Al3Sc/Al3Li Nanoscale Precipitates
  in Aluminum

abstract:
  An Al-11.3Li-0.11Sc (at. %) alloy was double-aged to induce first
alpha'-Al3Sc and then delta'-Al3Li precipitates. Atom-probe tomography revealed
both single-phase delta'-precipitates and core-shell alpha'/delta'-precipitates
(with respective average radii of 16 and 27 nm, and respective volume fractions
of 12 and 9%) conferring a high strength to the alloy. Although the
delta'-shells contain little Sc (~0.027 at. %), the alpha'-cores have a high Li
content, with an average composition of Al0.72(Sc0.17 Li0.11). The Li
concentrations within the delta'-phase and the Li interfacial excess at the
delta'/alpha'-interface both exhibit wide precipitate-to-precipitate
variations.


title: Inclination-Independent Galaxy Classification

abstract:
  We present a new method to classify galaxies from large surveys like the
Sloan Digital Sky Survey using inclination-corrected concentration,
inclination-corrected location on the color-magnitude diagram, and apparent
axis ratio. Explicitly accounting for inclination tightens the distribution of
each of these parameters and enables simple boundaries to be drawn that
delineate three different galaxy populations: Early-type galaxies, which are
red, highly concentrated, and round; Late-type galaxies, which are blue, have
low concentrations, and are disk dominated; and Intermediate-type galaxies,
which are red, have intermediate concentrations, and have disks. We have
validated our method by comparing to visual classifications of high-quality
imaging data from the Millennium Galaxy Catalogue. The inclination correction
is crucial to unveiling the previously unrecognized Intermediate class.
Intermediate-type galaxies, roughly corresponding to lenticulars and early
spirals, lie on the red sequence. The red sequence is therefore composed of two
distinct morphological types, suggesting that there are two distinct mechanisms
for transiting to the red sequence. We propose that Intermediate-type galaxies
are those that have lost their cold gas via strangulation, while Early-type
galaxies are those that have experienced a major merger that either consumed
their cold gas, or whose merger progenitors were already devoid of cold gas
(the ``dry merger'' scenario).


title: Stueckelberg Mechanism and Chiral Lagrangian for $Z'$ Boson

abstract:
  Traditional Stueckelberg Mechanism is shown equivalent to set up a gauged
U(1) chiral Lagrangian and fix special gauge. With this mechanism, the original
electro-weak chiral Lagrangian is inlarged by including an extra U(1) symmetry
to represent physics for $Z'$ boson. We build up complete list of electro-weak
chiral Lagrangian up to order of $p^4$ including $Z'$ and higgs bosons. The
most general mixing among neutral gauge bosons is diagonalized completely and
the connections among these operators to triple, quartic couplings involving
$Z'$ boson and to that in traditional electro-weak chiral Lagrangian are made.


title:
An extended class of minimax generalized Bayes estimators of regression
  coefficients

abstract:
  We derive minimax generalized Bayes estimators of regression coefficients in
the general linear model with spherically symmetric errors under invariant
quadratic loss for the case of unknown scale. The class of estimators
generalizes the class considered in Maruyama and Strawderman (2005) to include
non-monotone shrinkage functions.


title:
Transversely-intersecting D-branes at finite temperature and chiral
  phase transition

abstract:
  We consider Sakai-Sugimoto like models consisting of Dq-Dp-anti-Dp-branes
where flavor Dp and anti-Dp-branes transversely intersect color Dq-branes along
two (r+1)-dimensional subspaces. For some values of p and q, the theory of
intersections dynamically breaks non-Abelian chiral symmetry which is
holographically realized as a smooth connection of the flavor branes at some
point in the bulk of the geometry created by Dq-branes. We analyze the system
at finite temperature and map out different phases of the theory representing
chiral symmetry breaking and restoration. For q<5 we find that, unlike the
zero-temperature case, there exist two branches of smoothly-connected solutions
for the flavor branes, one getting very close to the horizon of the background
and the other staying farther away from it. At low temperatures, the solution
which stays farther away from the horizon determines the vacuum. For background
D5 and D6-branes we find that the flavor branes, like the zero temperature
case, show subtle behavior whose dual gauge theory interpretation is not clear.
We conclude with some comments on how chiral phase transition in these models
can be seen from their open string tachyon dynamics.


title: Nevanlinna-Pick interpolation for $C+BH^\infty$

abstract:
  Given an inner function $B$ we classify the invariant subspaces of the
algebra $H^\infty_B:=\mathbb{C}+BH^\infty$. We derive a formula in terms of
these invariant subspaces for the distance of an element in $L^\infty$ to a
certain weak*-closed ideal in $H^\infty_B$ and use this to prove an analogue of
the Nevanlinna-Pick interpolation theorem.


title: Correlated electronic structure of LaOFeAs

abstract:
  We compute the electronic structure, momentum resolved spectral function and
optical conductivity of the new superconductor LaO$_{1-x}$F$_x$FeAs within the
combination of the Density functional theory and the Dynamical Mean Field
Theory. We find that the compound in the normal state is a strongly correlated
metal and the parent compound is a bad metal at the verge of the metal
insulator transition. We argue that the superconductivity is not phonon
mediated.


title: The ground state energy at unitarity

abstract:
  We consider two-component fermions on the lattice in the unitarity limit.
This is an idealized limit of attractive fermions where the range of the
interaction is zero and the scattering length is infinite. Using Euclidean time
projection, we compute the ground state energy using four computationally
different but physically identical auxiliary-field methods. The best
performance is obtained using a bounded continuous auxiliary field and a
non-local updating algorithm called hybrid Monte Carlo. With this method we
calculate results for 10 and 14 fermions at lattice volumes 4^3, 5^3, 6^3, 7^3,
8^3 and extrapolate to the continuum limit. For 10 fermions in a periodic cube,
the ground state energy is 0.292(12) times the ground state energy for
non-interacting fermions. For 14 fermions the ratio is 0.329(5).


title: On Scale Determination in Lattice QCD with Dynamical Quarks

abstract:
  Dependence of $a/r_c$ (inverse Sommer parameter in units of lattice spacing
$a$) on $am_q$ (quark mass in lattice unit) has been observed in all lattice
QCD simulations with sea quarks including the ones with improved actions. How
much of this dependence is a scaling violation has remained an intriguing
question. Our approach has been to investigate the issue with an action with
known lattice artifacts, i.e., the standard Wilson quark and gauge action with
$\beta=5.6$ and 2 degenerate flavors of sea quarks on $ 16^3 \times 32 $
lattices. In order to study in detail the sea quark mass dependence,
measurements are carried out at eight values of the Wilson hopping parameter
$\kappa$ in the range 0.156 - 0.158 corresponding to PCAC quark mass values
$am_q$ from about 0.07 to below 0.015. We analyze the static potential by
fitting to the familiar phenomenological form and extract $a/r_c$. Though
scaling violations may indeed be present for relatively large $am_q$, a
consistent scenario at sufficiently small $am_q$ seems to emerge in the
mass-independent scheme where for a fixed $\beta$, $1/r_0$ and $\sqrt{\sigma}$
have linear dependence on $m_q$ as physical effects similar to the quark mass
dependence of the rho mass. We present evidence for this scenario and
accordingly extract the lattice scale $a$ by chiral extrapolation to the
physical point. Care has been exercised to determine optimal values of all
fitting parameters and accuracy of the chiral extrapolation. An independent
determination of the scale $a$ by chiral extrapolation of the rho mass is
consistent with the scale obtained above ($a$ = 0.08041(12)(77) fm, $a^{-1}$ =
2.454(4)(23) GeV).


title:
Doping-dependent Phase Diagram of LaO{\it M}As ({\it M}=V--Cu) and
  Electron-type Superconductivity near Ferromagnetic Instability

abstract:
  By first-principles calculations, we present a doping-dependent phase diagram
of LaO{\it M}As ({\it M}=V--Cu) family. It is characterized as
antiferromagnetic semiconductor around LaOMnAs side and ferromagnetic metal
around LaOCoAs. Both LaOFeAs and LaONiAs, where superconductivity were
discovered, are located at the borderline of magnetic phases. Extensive Fermi
surface analysis suggests that the observed superconductivity is of
electron-type in its origin. We discuss possible pairing mechanisms in the
context of competing ferromagnetic phases found in this work and the
ferromagnetic spin fluctuations.


title: Chernoff and Trotter type product formulas

abstract:
  We consider the abstract Cauchy problem x'=Ax, x(0)=x_0\in D(A) for linear
operators A on a Banach space X. We prove uniqueness of the (local) solution of
this problem for a natural class of operators A. Moreover, we establish that
the solution x(\cdot) can be represented as a limit of sequence F(t/n)^{n} as
n\to\infty in the weak operator topology, where a function F:[0,\infty)\to L(X)
satisfies F'(0)y=Ay, y\in D(A). As a consequence, we deduce necessary and
sufficient conditions that a linear operator C is closable and its closure is a
generator of C_0-semigroup. We also obtain some criteria for the sum of two
generators of C_0-semigroups to be a generator of C_0-semigroup such that the
Trotter formula is valid.


title: Isoparametric hypersurfaces with four principal curvatures revisited

abstract:
  The classification of isoparametric hypersurfaces with four principal
curvatures in spheres in [2] hinges on a crucial characterization, in terms of
four sets of equations of the 2nd fundamental form tensors of a focal
submanifold, of an isoparametric hypersurface of the type constructed by Ferus,
Karcher and M\"{u}nzner. The proof of the characterization in [2] is an
extremely long calculation by exterior derivatives with remarkable
cancellations, which is motivated by the idea that an isoparametric
hypersurface is defined by an over-determined system of partial differential
equations. Therefore, exterior differentiating sufficiently many times should
gather us enough information for the conclusion. In spite of its elementary
nature, the magnitude of the calculation and the surprisingly pleasant
cancellations make it desirable to understand the underlying geometric
principles.
  In this paper, we give a conceptual, and considerably shorter, proof of the
characterization based on Ozeki and Takeuchi's expansion formula for the
Cartan-M\"{u}nzner polynomial. Along the way the geometric meaning of these
four sets of equations also becomes clear.


title: Relative regular modules. Applications to von Neumann regular rings

abstract:
  We use the concept of a regular object with respect to another object in an
arbitrary category, defined in \cite{dntd}, in order to obtain the transfer of
regularity in the sense of Zelmanowitz between the categories $R-$mod and
$S-$mod, when $S$ is an excellent extension of the ring $R$. Consequently, we
obtain a result of \cite{ps}: if $S$ is an excellent extension of the ring $R$,
then $S$ is von Neumann regular ring if and only if $R$ is also von Neumann
regular ring. In the second part, using relative regular modules, we give a new
proof of a classical result: the von Neumann regular property of a ring is
Morita invariant. Finally, the von Neumann regularity of the Morita ring is
investigated.


title: Mars and frame-dragging: study for a dedicated mission

abstract:
  In this paper we preliminarily explore the possibility of designing a
dedicated satellite-based mission to measure the general relativistic
gravitomagnetic Lense-Thirring effect in the gravitational field of Mars. The
focus is on the systematic error induced by the multipolar expansion of the
areopotential and on possible strategies to reduce it. It turns out that the
major sources of bias are the Mars'equatorial radius R and the even zonal
harmonics J_L, L = 2,4,6... of the areopotential. An optimal solution, in
principle, consists of using two probes at high-altitudes (a\approx 9500-9600
km) and different inclinations, and suitably combining their nodes in order to
entirely cancel out the bias due to \delta R. The remaining uncancelled
mismodelled terms due to \delta J_L, L = 2,4,6,... would induce a bias \lesssim
1%, according to the present-day MGS95J gravity model, over a wide range of
admissible values of the inclinations. The Lense-Thirring out-of-plane shifts
of the two probes would amount to about 10 cm yr^-1.


title: Top Production from Black Holes at the LHC

abstract:
  In theories with large extra dimension and with low quantum gravity scale
near a TeV, it is expected that TeV-scale black holes to be produced in
proton-proton collisions at the LHC with the center of mass energy of 14 TeV.
Since the black holes temperature can be around 1 TeV, top quark production is
expected from them via Hawking radiation. Within the Standard Model of particle
physics top quarks are produced via strong interaction in $t\bar{t}$ pairs or
via electroweak interaction singly. Therefore, black holes can be the new
source of top quark production. In this article we present the total cross
sections and transverse momentum distributions of top quark production from
black holes at the LHC. We find that the top quarks from black holes tend to
reside at very high transverse momentum region so it can be a very useful
signature for the black holes at the LHC.


title:
Upper critical field, Hall effect and magnetoresistance in the
  iron-based layered superconductor LaFeAsO_{0.9}F_{0.1-\delta}

abstract:
  By using a two-step method, we successfully synthesized the iron based new
superconductor LaFeAsO_{0.9}F_{0.1-\delta}$. The resistive transition curves
under different magnetic fields were measured, leading to the determination of
the upper critical field Hc2(T) of this new superconductor. The value of Hc2 at
zero temperature is estimated to be about 50 Tesla roughly. In addition, the
Hall effect and magnetoresistance were measured in wide temperature region. A
negative Hall coefficient R_H has been found, implying a dominant conduction
mainly by electron-like charge carriers in this material. The charge carrier
density determined at 100 K is about 9.8E20cm^{-3}, which is close to the
cuprate superconductors. It is further found that the magnetoresistance does
not follow Kohler's law. Meanwhile, the different temperature dependence
behaviors of resistivity, Hall coefficient, and magnetoresistance have
anomalous properties at about 230 K, which may be induced by some exotic
scattering mechanism.


title:
Reply on ``Comment on neutrino-mixing interpretation of the GSI time
  anomaly''by C. Giunti, arXiv:0801.4639 [nucl-th]

abstract:
  Here we reply critically to the comments by Giunti (arXiv:0801.4639
[nucl-th]) and justify our explanation of the experimentally observed periodic
interference term in the rate of the K-shell electron capture decay of the
H-like ions 140Pr58+ and 142Pm60+ as a neutrino-flavour mixing.


title: On the foundations and necessity of classical gauge invariance

abstract:
  We argue that, ideally, the ways to measure magnitudes in non-quantum
theories of physics (spacetime, field theory), limit drastically their possible
mathematical models. In particular, gauge invariance in the Yang-Mills
framework, is a necessity of our way of measuring rather than an a priori
imposition on symmetry.
  A general postulational basis for the geometric aspects of classical field
theories is introduced, and the permitted models are studied. Some of them (for
example, compatible with signature-changing metrics or variations of the speed
of interactions) are new, and require a generalization of the concept of
principal fiber bundle, which may be of interest both, physically and
mathematically.