title: A metageometric enquiry concerning time, space, and quantum physics

abstract:
  An enquiry into the physical nature of time and space and into the ontology
of quantum mechanics from a metageometric perspective, resulting from the
belief that geometric thought and language are powerless to farther
understanding of these issues, restricting instead physical progress.
  The nature and assumptions of quantum gravity are analysed critically,
including misgivings about the relevance of the Planck scale to it and its lack
of observational referent in the natural world.
  The anthropic foundations of geometry are investigated. The exclusive use of
geometric thought from antiquity to present-day physics is found to permeate
all new attempts towards better theories, including quantum gravity and, within
it, even pregeometry.
  The problem of the ether is found to have perpetuated itself up to the
present by transmuting its form from mechanical, through metric, to geometric.
  A clarification is made of the physical, mathematical, and psychological
foundations of relativity and quantum theories. The former is founded
geometrically on measurement-based clock-reading separations ds. The latter is
founded metageometrically on the experiment-based concepts of premeasurement
and transition things, inspired in the physically unexplored aspect of time as
a consciousness-related product. A concept of metageometric time is developed
and coordinate time t is recovered from it. Discovery of the connection between
quantum-mechanical metageometric time elements and general-relativistic clock
time elements ds is deemed necessary for a combined understanding of time.
  Time is conjectured to be the missing link between general relativity and
quantum mechanics.


title: Strong Lensing by Binary Galaxies Modelled as Isothermal Spheres

abstract:
  We study the problem of gravitational lensing by binary galaxies, idealized
as two isothermal spheres. In a wide binary, each galaxy possesses individual
tangential, nearly astroidal, caustics and roundish radial caustics. As the
separation of the binary is made smaller, the caustics undergo a sequence of
metamorphoses. The first metamorphosis occurs when the tangential caustics
merge to form a single six-cusped caustic, lying interior to the radial
caustics. At still smaller separations, the six-cusped caustic undergoes the
second metamorphosis and splits into a four-cusped caustic and two three-cusped
caustics, which shrink to zero size (an elliptic umbilic catastrophe) before
they enlarge again and move away from the origin perpendicular to the binary
axis. Finally, a third metamorphosis occurs as the three-cusp caustics join the
radial caustics, leaving an inner distorted astroid caustic enclosed by two
outer caustics. The maximum number of images possible is 7. Classifying the
multiple imaging according to critical isochrones, there are only 8
possibilities: 2 three-image cases, 3 five-image cases, and 3 seven-image
cases. When the isothermal spheres are singular, the core images vanish into
the central singularity. The number of images may then be 1, 2, 3, 4 or 5,
depending on the source location, and the separation and masses of the pair of
lensing galaxies. The locations of metamorphoses, and the onset of threefold
and fivefold multiple imaging, can be worked out analytically in this case.


title: On Multiple Einstein Rings

abstract:
  A number of recent surveys for gravitational lenses have found examples of
double Einstein rings. Here, we investigate analytically the occurrence of
multiple Einstein rings. We prove, under very general assumptions, that at most
one Einstein ring can arise from a mass distribution in a single plane lensing
a single background source. Two or more Einstein rings can therefore only occur
in multi-plane lensing. Surprisingly, we show that it is possible for a single
source to produce more than one Einstein ring. If two point masses (or two
isothermal spheres) in different planes are aligned with observer and source on
the optical axis, we show that there are up to three Einstein rings. We also
discuss the image morphologies for these two models if axisymmetry is broken,
and give the first instances of magnification invariants in the case of two
lens planes.


title: Big-Bang Nucleosynthesis and Gravitino

abstract:
  We derive big-bang nucleosynthesis (BBN) constraints on both unstable and
stable gravitino taking account of recent progresses in theoretical study of
the BBN processes as well as observations of primordial light-element
abundances. In the case of unstable gravitino, we set the upper limit on the
reheating temperature assuming that the primordial gravitinos are mainly
produced by the scattering processes of thermal particles. For stable
gravitino, we consider Bino, stau and sneutrino as the next-to-the-lightest
supersymmetric particle and obtain constraints on their properties. Compared
with the previous works, we improved the following points: (i) we use the most
recent observational data, (ii) for gravitino production, we include
contribution of the longitudinal component, and (iii) for the case with
unstable long-lived stau, we estimate the bound-state effect of stau accurately
by solving the Boltzmann equation.


title: Geometry of Weyl theory for Jacobi matrices with matrix entries

abstract:
  A Jacobi matrix with matrix entries is a self-adjoint block tridiagonal
matrix with invertible blocks on the off-diagonals. The Weyl surface describing
the dependence of Green's matrix on the boundary conditions is interpreted as
the set of maximally isotropic subspace of a quadratic from given by the
Wronskian. Analysis of the possibly degenerate limit quadratic form leads to
the limit point/limit surface theory of maximal symmetric extensions for
semi-infinite Jacobi matrices with matrix entries with arbitrary deficiency
indices. The resolvent of the extensions is explicitly calculated.


title:
On the $p$-adic distance between a point of finite order and a curve of
  genus higher or equal to two

abstract:
  Let $A$ be an abelian variety over ${\bf C}_p$ ($p$ a prime number) and
$V\hookrightarrow A$ a closed subvariety. The conjecture of Tate-Voloch
predicts that the $p$-adic distance from a torsion point $T\not\in V({\bf
C}_p)$ to the variety $V$ is bounded below by a strictly positive constant.
This conjecture is proven by Hrushovski and Scanlon, when $A$ has a model over
$\bar{{\bf C}}_p$. We give an explicit formula for this constant, in the case
where $V$ is a curve embedded into its Jacobian and $V$ has a model over a
number field. This explicit formula involves analytic and arakelovian
invariants of the curve.


title: Ratios of Norms for Polynomials and Connected n-width Problems

abstract:
  Let G be a bounded simply connected domain and E be a regular compact subset
of G with connected complement. We investigate the asymptotic behavior of the
Kolmogorov k-width, k=k(n), of the set of polynomials of degree at most n
having the supremum norm at most 1 on G restricted to E in the space of
continuous functions on E.


title:
Asymptotic evolution of smooth curves under geodesic flow on hyperbolic
  manifolds - II

abstract:
  Extending the earlier results for analytic curve segments, in this article we
describe the asymptotic behaviour of evolution of a finite segment of a
C^n-smooth curve under the geodesic flow on the unit tangent bundle of a finite
volume hyperbolic n-manifold. In particular, we show that if the curve
satisfies certain natural geometric conditions, the pushforward of the
parameter measure on the curve under the geodesic flow converges to the
normalized canonical Riemannian measure on the tangent bundle in the limit. We
also study the limits of geodesic evolution of shrinking segments.
  We use Ratner's classification of ergodic invariant measures for unipotent
flows on homogeneous spaces of SO(n,1), and an observation relating local
growth properties of smooth curves and dynamics of linear SL(2,R)-actions.


title: Mixed sums of squares and triangular numbers (III)

abstract:
  In this paper we confirm a conjecture of Sun which states that each positive
integer is a sum of a square, an odd square and a triangular number. Given any
positive integer m, we show that p=2m+1 is a prime congruent to 3 modulo 4 if
and only if T_m=m(m+1)/2 cannot be expressed as a sum of two odd squares and a
triangular number, i.e., p^2=x^2+8(y^2+z^2) for no odd integers x,y,z. We also
show that a positive integer cannot be written as a sum of an odd square and
two triangular numbers if and only if it is of the form 2T_m (m>0) with 2m+1
having no prime divisor congruent to 3 modulo 4.


title: Equivariant sl(n)-link homology

abstract:
  For every positive integer $n$ we construct a bigraded homology theory for
links, such that the corresponding invariant of the unknot is closely related
to the U(n)-equivariant cohomology ring of $\mathbb{CP}^{n-1}$; our
construction specializes to the Khovanov-Rozansky $sl_n$-homology. We are
motivated by the "universal" rank two Frobenius extension studied by M.
Khovanov in \cite{Kh3} for $sl_2$-homology.


title: The privacy implications of Bluetooth

abstract:
  A substantial amount of research, as well as media hype, has surrounded RFID
technology and its privacy implications. Currently, researchers and the media
focus on the privacy threats posed by RFID, while consumer groups choose to
boycott products bearing RFID tags. At the same, however, a very similar
technology has quietly become part of our everyday lives: Bluetooth. In this
paper we highlight the fact that Bluetooth is a widespread technology that has
real privacy implications. Furthermore, we explore the applicability of
RFID-based solutions to address these privacy implications.


title:
Measures with positive Lyapunov exponent and conformal measures in
  rational dynamics

abstract:
  Ergodic properties of rational maps are studied, generalising the work of F.\
Ledrappier. A new construction allows for simpler proofs of stronger results.
Very general conformal measures are considered. Equivalent conditions are given
for an ergodic invariant probability measure with positive Lyapunov exponent to
be absolutely continuous with respect to a general conformal measure. If they
hold, we can construct an induced expanding Markov map with integrable return
time which generates the invariant measure.


title:
Kinematic quantities for a spherical distribution of uniformly
  accelerated observers

abstract:
  The kinematical quantities derived from the velocity field of a nongeodesic
congruence are studied. We found the shear tensor components are finite in time
but diverge at the event horizon of the spacetime located at $\rho = 0$. The
surface gravity on the horizon is just the proper acceleration of the uniformly
expanding distribution of observers, in spherical Rindler coordinates. The
Raychaudhuri equation is fulfilled for the congruence of particles worldlines.


title: A Higher Order Perturbative Parton Evolution Toolkit (HOPPET)

abstract:
  This document describes a Fortran 95 package for carrying out DGLAP evolution
and other common manipulations of parton distribution functions (PDFs). The
PDFs are represented on a grid in x-space so as to avoid limitations on the
functional form of input distributions. Good speed and accuracy are obtained
through the representation of splitting functions in terms of their convolution
with a set of piecewise polynomial basis functions, and Runge-Kutta techniques
are used for the evolution in Q. Unpolarised evolution is provided to NNLO,
including heavy-quark thresholds in the MSbar scheme, and longitudinally
polarised evolution to NLO. The code is structured so as to provide simple
access to the objects representing splitting functions and PDFs, making it
possible for a user to extend the facilities already provided. A streamlined
interface is also available, facilitating use of the evolution part of the code
from F77 and C/C++.


title: Real double coset spaces and their invariants

abstract:
  Let G be a real form of a complex reductive group. Suppose that we are given
involutions \sigma and \theta of G. Let H=G^\sigma denote the fixed group of
\sigma and let K=G^\theta denote the fixed group of \theta. We are interested
in calculating the double coset space H\backslash G/K. We use moment map and
invariant theoretic techniques to calculate the double cosets, especially the
ones that are closed. One salient point of our results is a stratification of a
quotient of a compact torus over which the closed double cosets fiber as a
collection of trivial bundles.


title: Graded mapping cone theorem, multisecants and syzygies

abstract:
  Let $X$ be a reduced closed subscheme in $\mathbb P^n$. As a slight
generalization of property $\textbf{N}_p$ due to Green-Lazarsfeld, we can say
that $X$ satisfies property $\textbf{N}_{2,p}$ scheme-theoretically if there is
an ideal $I$ generating the ideal sheaf $\mathcal I_{X/\P^n}$ such that $I$ is
generated by quadrics and there are only linear syzygies up to $p$-th step (cf.
\cite{EGHP1}, \cite{EGHP2}, \cite{V}). Recently, many algebraic and geometric
results have been proved for projective varieties satisfying property
$\textbf{N}_{2,p}$(cf. \cite{CKP}, \cite{EGHP1}, \cite{EGHP2} \cite {KP}). In
this case, the Castelnuovo regularity and normality can be obtained by the
blowing-up method as $\reg(X)\le e+1$ where $e$ is the codimension of a smooth
variety $X$ (cf. \cite{BEL}). On the other hand, projection methods have been
very useful and powerful in bounding Castelnuovo regularity, normality and
other classical invariants in geometry(cf. \cite{BE}, \cite{K}, \cite{KP},
\cite{L} \cite {R}).
  In this paper, we first prove the graded mapping cone theorem on partial
eliminations as a general algebraic tools and give some applications. Then, we
bound the length of zero dimensional intersection of $X$ and a linear space $L$
in terms of graded Betti numbers and deduce a relation between $X$ and its
projections with respect to the geometry and syzygies in the case of projective
schemes satisfying property $\textbf{N}_{2,p}$ scheme-theoretically. In
addition, we give not only interesting information on the regularity of fibers
and multiple loci for the case of $\textbf{N}_{d,p}, d\ge 2$ but also geometric
structures for projections according to moving the center.


title: Bistability and mode interaction in microlasers

abstract:
  We investigate the possibility of bistable lasing in microcavity lasers as
opposed to bulk lasers. To that end, the dynamic behavior of a microlaser
featuring two coupled, interacting modes is analytically investigated within
the framework of a semiclassical laser model, suitable for a wide range of
cavity shapes and mode geometries. Closed-form coupled mode equations are
obtained for all classes of laser dynamics. We show that bistable operation is
possible in all of these classes. In the simplest case (class-A lasers)
bistability is shown to result from an interplay between coherent
(population-pulsation) and incoherent (hole-burning) processes of mode
interaction. We find that microcavities offer better conditions to achieve
bistable lasing than bulk cavities, especially if the modes are not degenerate
in frequency. This results from better matching of the spatial intensity
distribution of microcavity modes. In more complicated laser models (class-B
and class-C) bistability is shown to persist for modes even further apart in
frequency than in the class-A case. The predictions of the coupled mode theory
have been confirmed using numerical finite-difference time-domain calculations.


title: Fourier series on compact symmetric spaces

abstract:
  The Fourier coefficients F(t) of a function f on a compact symmetric space
U/K are given by integration of f against matrix coefficients of irreducible
representations of U. The coefficients depend on a spectral parameter t, which
determines the representation, and they can be represented by elements F(t) in
a common Hilbert space H.
  We obtain a theorem of Paley-Wiener type which describes the size of the
support of f by means of the exponential type of a holomorphic H-valued
extension of F, provided f is K-finite and of sufficiently small support. The
result was obtained previously for K-invariant functions, to which case we
reduce.


title:
On `The spectral and temporal properties of an Ultra--Luminous X-ray
  source in NGC 6946', by Senorita Devi et al

abstract:
  A recent paper (arXiv:0804.3463) claims that the presence of a soft X-ray
component in an X-ray source in NGC 6946 provides strong evidence that its
black hole mass is definitely $>100\msun$, and more probably $\sim 400\msun$,
even if the source is beamed.
  I show that the data are instead very compatible with a black hole mass of
only $5\msun$, radiating isotropically (i.e. no beaming) and a mass transfer
rate about 60 times the Eddington value, i.e. $1.25 \times 10^{-5} \msun {\rm
yr}^{-1}$. Such a system is very similar to the probable descendant of the
Galactic X-ray binary Cygnus X--1 once the supergiant companion evolves to fill
its Roche lobe.


title:
Cauchy-Pompeiu type formulas for d-bar on affine algebraic Riemann
  surfaces and some applications

abstract:
  We have obtained the explicit versions and precisions for the Hodge-Riemann
decomposition of formes on affine algebraic curve V. The main application
consists in the construction of Faddeev-Green function for Laplacian on V.
Basing on this [HM](arXiv:0804.3951 and J.Geom.Anal., 2008,18), we extended
from the case X in C to the case of bordered Riemann surface X in V the
R.Novikov (1988) scheme for the effective reconstruction of conductivity
function sigma on X through Dirichlet-to-Neumann mapping on bX for solutions of
d(sigma d^cU)=0. In Sec.4 we give a correction of the paper [HM].


title:
From formal proofs to mathematical proofs: a safe, incremental way for
  building in first-order decision procedures

abstract:
  We investigate here a new version of the Calculus of Inductive Constructions
(CIC) on which the proof assistant Coq is based: the Calculus of Congruent
Inductive Constructions, which truly extends CIC by building in arbitrary
first-order decision procedures: deduction is still in charge of the CIC
kernel, while computation is outsourced to dedicated first-order decision
procedures that can be taken from the shelves provided they deliver a proof
certificate. The soundness of the whole system becomes an incremental property
following from the soundness of the certificate checkers and that of the
kernel. A detailed example shows that the resulting style of proofs becomes
closer to that of the working mathematician.


title: Physics Revealed at Intermediate p_T

abstract:
  A review is given on the subject of hadron production at intermediate $p_T$
in heavy-ion collisions. The underlying dynamical processes are inferred from
interpreting the data in the framework of recombination. Ridge formation with
or without triggers is found to play an important role in nearly all
observables in that $p_T$ region. Correlation data would be hard to interpret
without taking ridges into account. The semi-hard partons that create the
ridges may even be able to drive elliptic flow without fast thermalization.


title:
Conditions implying the uniqueness of the weak$^*$-topology on certain
  group algebras

abstract:
  We investigate possible preduals of the measure algebra $M(G)$ of a locally
compact group and the Fourier algebra $A(G)$ of a separable compact group. Both
of these algebras are canonically dual spaces and the canonical preduals make
the multiplication separately weak$^*$-continuous so that these algebras are
dual Banach algebras. In this paper we find additional conditions under which
the preduals $C_0(G)$ of $M(G)$ and $C^*(G)$ of $A(G)$ are uniquely determined.
In both cases we consider a natural coassociative multiplication and show that
the canonical predual gives rise to the unique weak$^*$-topology making both
the multiplication separately weak$^*$-continuous and the coassociative
multiplication weak$^*$-continuous. In particular, dual cohomological
properties of these algebras are well defined with this additional structure.


title:
Groups of generalized flux transformations in the space of generalized
  connections

abstract:
  We present a group of transformations in the space of generalized connections
that contains the set of transformations generated by the flux variables of
loop quantum gravity. This group is labelled by certain SU(2)-valued functions
on the bundle of directions in the spatial manifold. A further generalization
is obtained by considering functions that depend on germs of analytic curves,
rather than just on directions.


title:
Chemical evolution of galaxies. I. A composition-dependent SPH model for
  chemical evolution and cooling

abstract:
  We describe an SPH model for chemical enrichment and radiative cooling in
cosmological simulations of structure formation. This model includes: i) the
delayed gas restitution from stars by means of a probabilistic approach
designed to reduce the statistical noise and, hence, to allow for the study of
the inner chemical structure of objects with moderately high numbers of
particles; ii) the full dependence of metal production on the detailed chemical
composition of stellar particles by using, for the first time in SPH codes, the
Qij matrix formalism that relates each nucleosynthetic product to its sources;
and iii) the full dependence of radiative cooling on the detailed chemical
composition of gas particles, achieved through a fast algorithm using a new
metallicity parameter zeta(T) that gives the weight of each element on the
total cooling function. The resolution effects and the results obtained from
this SPH chemical model have been tested by comparing its predictions in
different problems with known theoretical solutions. We also present some
preliminary results on the chemical properties of elliptical galaxies found in
self-consistent cosmological simulations. Such simulations show that the above
zeta-cooling method is important to prevent an overestimation of the
metallicity-dependent cooling rate, whereas the Qij formalism is important to
prevent a significant underestimation of the [alpha/Fe] ratio in simulated
galaxy-like objects.


title:
Dynamical evolution of correlated spontaneous emission of a single
  photon from a uniformly excited cloud of N atoms

abstract:
  We study the correlated spontaneous emission from a dense spherical cloud of
N atoms uniformly excited by absorption of a single photon. We find that the
decay of such a state depends on the relation between an effective Rabi
frequency Omega, which is proportional to sqrt{N}, and the time of photon
flight through the cloud R/c. If Omega*R/c < 1 the state exponentially decays
with rate Omega^{2}*R/c and the state life time is greater then R/c. In the
opposite limit Omega*R/c >> 1, the coupled atom-radiation system oscillates
between the collective Dicke state (with no-photons) and the atomic ground
state (with one photon) with frequency Omega while decaying at a rate c/R.


title: The origin of a$_{1g}$ and e$_g$' orderings in Na$_x$CoO$_2$

abstract:
  It has often been suggested that correlation effects suppress the small e_g'
Fermi surface pockets of NaxCoO_2 that are predicted by LDA, but absent in
ARPES measurements. It appears that within the dynamical mean field theory
(DMFT) the ARPES can be reproduced only if the on-site energy of the eg'
complex is lower than that of the a1g complex at the one-electron level, prior
to the addition of local correlation effects. Current estimates regarding the
order of the two orbital complexes range from -200 meV to 315 meV in therms of
the energy difference. In this work, we perform density functional theory
calculations of this one-electron splitting \Delta= \epsilon_a1g-\epsilon_e_g'
for the full two-layer compound, Na2xCo2O4, accounting for the effects of Na
ordering, interplanar interactions and octahedral distortion. We find that
\epsilon a_1g-\epsilon e_g' is negative for all Na fillings and that this is
primarily due to the strongly positive Coulomb field created by Na+ ions in the
intercalant plane. This field disproportionately affects the a_1g orbital which
protrudes farther upward from the Co plane than the e_g' orbitals. We discuss
also the secondary effects of octahedral compression and multi-orbital filling
on the value of \Delta as a function of Na content. Our results indicate that
if the e_g' pockets are indeed suppressed that can only be due to nonlocal
correlation effects beyond the standard DMFT.


title: Siegel modular forms and finite symplectic groups

abstract:
  The finite symplectic group Sp(2g) over the field of two elements has a
natural representation on the vector space of Siegel modular forms of given
weight for the principal congruence subgroup of level two. In this paper we
decompose this representation, for various (small) values of the genus and the
level, into irreducible representations. As a consequence we obtain uniqueness
results for certain modular forms related to the superstring measure, a better
understanding of certain modular forms in genus three studied by D'Hoker and
Phong as well as a new construction of Miyawaki's cusp form of weight twelve in
genus three.


title:
Energy dependence of Lambda and Xi production in central Pb+Pb
  collisions at 20A, 30A, 40A, 80A, and 158A GeV measured at the CERN Super
  Proton Synchrotron

abstract:
  Results on $\Lambda$, $\bar{\Lambda}}$, $\Xi^{-}$, and $\bar{\Xi}^{+}$
production in central Pb+Pb reactions at 20A, 30A, 40A, 80A, and 158A GeV are
presented. The energy dependence of transverse mass spectra, rapidity spectra,
and multiplicities is discussed. Comparisons to string hadronic models (UrQMD
and HSD) and statistical hadron gas models are shown. While the latter provide
a reasonable description of all particle yields, the first class of models
fails to match the $\Xi^{-}$, and $\bar{\Xi}^{+}$ multiplicities.


title:
Full One-loop Electro-Weak Corrections to Three-jet Observables at the Z
  pole and Beyond

abstract:
  We describe the impact of the full one-loop EW terms of O(alpha_s alpha_EM^3)
entering the electron-positron into three-jet cross-section from \sqrt{s}=M_Z
to TeV scale energies. We include both factorisable and non-factorisable
virtual corrections, photon bremsstrahlung but not the real emission of W and Z
bosons. Their importance for the measurement of alpha_S from jet rates and
shape variables is explained qualitatively and illustrated quantitatively.


title: The ideal structure of reduced crossed products

abstract:
  Let (A,G) be a C*-dynamical system with G discrete. In this paper we
investigate the ideal structure of the reduced crossed product C*-algebra and
in particular we determine sufficient - and in some cases also necessary -
conditions for A to separate the ideals in Ax_rG. When A separates the ideals
in Ax_rG, then there is a one-to-one correspondence between the ideals in Ax_rG
and the invariant ideals in A. We extend the concept of topological freeness
and present a generalization of the Rokhlin property. Exactness properties of
(A,G) turns out to be crucial in these investigations.


title: Lorentz invariant photon number density

abstract:
  A Lorentz invariant positive definite expression for photon number density is
derived as the absolute square of the invariant scalar product of a
polarization sensitive position eigenvector and the photon wave function. It is
found that this scalar product is independent of the form chosen for the wave
function and that the normalized positive frequency vector potential-electric
field pair is a convenient choice of wave function in the presence of matter.
The number amplitude describing a localized state is a delta-function at the
instant at which localization and detection are seen as simultaneous.


title: Quantum Dynamics with Mean Field Interactions: a New Approach

abstract:
  We propose a new approach for the study of the time evolution of a factorized
$N$-particle bosonic wave function with respect to a mean-field dynamics with a
bounded interaction potential. The new technique, which is based on the control
of the growth of the correlations among the particles, leads to quantitative
bounds on the difference between the many-particle Schr\"odinger dynamics and
the one-particle nonlinear Hartree dynamics. In particular the one-particle
density matrix associated with the solution to the $N$-particle Schr\"odinger
equation is shown to converge to the projection onto the one-dimensional
subspace spanned by the solution to the Hartree equation with a speed of
convergence of order 1/N for all fixed times.


title: Comment on "Superinsulator and Quantum Synchronization"

abstract:
  We show that the "theory" of "superinsulating" state presented by V.Vinokur
et al (Nature vol. 452, p. 613, 2008) and Fistul et al (Phys. Rev. Lett. vol.
100, 086805, 2008) is essentially incorrect due to a sequence of errors in the
theoretical analysis of the standard model of Josephson arrays which properties
have been carefully studied and described in the literature. The line of
calculations suggested in these articles lead to unphysical results. In
particular, the calculations predict a direct current flowing through a
capacitor. Moreover, this current may flow even in the absence of voltage - a
sort of supercurrent flowing in the "superinsulating" state. We also question
that the theoretical model employed in these works, even if treated correctly,
is applicable to the analysis of experimental data on homogeneously disordered
superconductive films.


title: Sequence Nets

abstract:
  We study a new class of networks, generated by sequences of letters taken
from a finite alphabet consisting of $m$ letters (corresponding to $m$ types of
nodes) and a fixed set of connectivity rules. Recently, it was shown how a
binary alphabet might generate threshold nets in a similar fashion [Hagberg et
al., Phys. Rev. E 74, 056116 (2006)]. Just like threshold nets, sequence nets
in general possess a modular structure reminiscent of everyday life nets, and
are easy to handle analytically (i.e., calculate degree distribution, shortest
paths, betweenness centrality, etc.). Exploiting symmetry, we make a full
classification of two- and three-letter sequence nets, discovering two new
classes of two-letter sequence nets. The new sequence nets retain many of the
desirable analytical properties of threshold nets while yielding richer
possibilities for the modeling of everyday life complex networks more
faithfully.


title: Dark energy interacting with two fluids

abstract:
  A cosmological model of dark energy interacting with dark matter and another
general component of the universe is investigated. We found general constraints
on these models imposing an accelerated expansion. The same is also studied in
the case for holographic dark energy.


title:
Decay estimates and smoothness for solutions of the dispersion managed
  non-linear Schr\"odinger equation

abstract:
  We study the decay and smoothness of solutions of the dispersion managed
non-linear Schr\"odinger equation in the case of zero residual dispersion.
Using new x-space versions of bilinear Strichartz estimates, we show that the
solutions are not only smooth, but also fast decaying.


title: On Estimation of Finite Population Proportion

abstract:
  In this paper, we study the classical problem of estimating the proportion of
a finite population. First, we consider a fixed sample size method and derive
an explicit sample size formula which ensures a mixed criterion of absolute and
relative errors. Second, we consider an inverse sampling scheme such that the
sampling is continue until the number of units having a certain attribute
reaches a threshold value or the whole population is examined. We have
established a simple method to determine the threshold so that a prescribed
relative precision is guaranteed. Finally, we develop a multistage sampling
scheme for constructing fixed-width confidence interval for the proportion of a
finite population. Powerful computational techniques are introduced to make it
possible that the fixed-width confidence interval ensures prescribed level of
coverage probability.


title:
Self-consistent single-nucleon and single-Lambda potentials in strange
  nuclear matter with the Dirac-Brueckner-Hartree-Fock approach

abstract:
  We calculate self-consistent single-nucleon and single-Lambda potentials in
hyperonic matter for different Lambda concentrations. The predictions include
relativistic Dirac effects as reported previously in a calculation of the
Lambda binding energy in symmetric nuclear matter. We discuss the dependence on
momentum, density, and Lambda fraction.


title: Hecke group algebras as quotients of affine Hecke algebras at level 0

abstract:
  The Hecke group algebra $HW_0$ of a finite Coxeter group $W_0$, as introduced
by the first and last author, is obtained from $W_0$ by gluing appropriately
its 0-Hecke algebra and its group algebra. In this paper, we give an equivalent
alternative construction in the case when $W_0$ is the classical Weyl group
associated to an affine Weyl group $W$. Namely, we prove that, for $q$ not a
root of unity, $HW_0$ is the natural quotient of the affine Hecke algebra
through its level 0 representation. We further show that the level 0
representation is a calibrated principal series representation for a suitable
choice of character, so that the quotient factors (non trivially) through the
principal central specialization. This explains in particular the similarities
between the representation theory of the classical 0-Hecke algebra and that of
the affine Hecke algebra at this specialization.


title: Noncommutative Nonlinear Sigma Models and Integrability

abstract:
  We first review the result that the noncommutative principal chiral model has
an infinite tower of conserved currents, and discuss the special case of the
noncommutative CP^1 model in some detail. Next, we focus our attention to a
submodel of the CP^1 model in the noncommutative spacetime A_\theta(R^2+1). By
extending a generalized zero curvature representation to A_\theta(R^2+1) we
discuss its integrability and construct its infinitely many conserved currents.
Supersymmetric principal chiral model with and without the WZW term and a
supersymmetric extension of the CP^1 submodel in noncommutative spacetime (i.e
in superspaces A_\theta(R^1+1|2), A_\theta(R^2+1|2)) are also examined in
detail and their infinitely many conserved currents are given in a systematic
manner. Finally, we discuss the solutions of the aforementioned submodels with
or without supersymmetry.


title: Super-exponential decay of Diffraction Managed Solitons

abstract:
  This is the second part of a series of papers where we develop rigorous decay
estimates for breather solutions of an averaged version of the non-linear
Schr\"odinger equation. In this part we study the diffraction managed discrete
non-linear Schr\"odinger equation, an equation which describes coupled
waveguide arrays with periodic diffraction management geometries. We show that,
for vanishing average diffraction, all solutions of the non-linear and
non-local diffraction management equation decay super-exponentially. As a
byproduct of our method, we also have a simple proof of existence of
diffraction managed solitons in the case of vanishing average diffraction.


title:
On the metric distortion of nearest-neighbour graphs on random point
  sets

abstract:
  We study the graph constructed on a Poisson point process in $d$ dimensions
by connecting each point to the $k$ points nearest to it. This graph a.s. has
an infinite cluster if $k > k_c(d)$ where $k_c(d)$, known as the critical
value, depends only on the dimension $d$. This paper presents an improved upper
bound of 188 on the value of $k_c(2)$. We also show that if $k \geq 188$ the
infinite cluster of $\NN(2,k)$ has an infinite subset of points with the
property that the distance along the edges of the graphs between these points
is at most a constant multiplicative factor larger than their Euclidean
distance. Finally we discuss in detail the relevance of our results to the
study of multi-hop wireless sensor networks.


title: Estimates of Effective Hubbard Model Parameters for C20 isomers

abstract:
  We report on an effective Hubbard Hamiltonian approach for the study of
electronic correlations in C$_{20}$ isomers, cage, bowl and ring, with quantum
Monte Carlo and exact diagonalization methods. The tight-binding hopping
parameter, $t$, in the effective Hamiltonian is determined by a fit to density
functional theory calculations, and the on-site Coulomb interaction, $U/t$, is
determined by calculating the isomers' affinity energies, which are compared to
experimental values. For the C$_{20}$ fullerene cage we estimate $t_{\rm
cage}\simeq 0.68-1.36$ eV and $(U/t)_{\rm cage} \simeq 7.1-12.2$. The resulting
effective Hamiltonian is then used to study the shift of spectral peaks in the
density of states of neutral and one-electron-doped C$_{20}$ isomers. Energy
gaps are also extracted for possible future comparison with experiments.


title: Azimuthal decorrelations between QCD jets at all orders

abstract:
  A quantity that promises to reveal important information on perturbative and
non-perturbative QCD dynamics is the azimuthal decorrelation between jets in
different hard processes. In order to access this information fixed-order NLO
predictions need to be supplemented by resummation of logarithmic terms which
are large in the region where the jets are nearly back-to-back in azimuth. In
the present letter we carry out this resummation to next-to--leading
logarithmic accuracy explaining the important role played by the recombination
scheme in general resummations for such jet observables.


title:
Initial data for black hole-neutron star binaries: a flexible,
  high-accuracy spectral method

abstract:
  We present a new numerical scheme to solve the initial value problem for
black hole-neutron star binaries. This method takes advantage of the
flexibility and fast convergence of a multidomain spectral representation of
the initial data to construct high-accuracy solutions at a relatively low
computational cost. We provide convergence tests of the method for both
isolated neutron stars and irrotational binaries. In the second case, we show
that we can resolve the small inconsistencies that are part of the
quasi-equilibrium formulation, and that these inconsistencies are significantly
smaller than observed in previous works. The possibility of generating a wide
variety of initial data is also demonstrated through two new configurations
inspired by results from binary black holes. First, we show that choosing a
modified Kerr-Schild conformal metric instead of a flat conformal metric allows
for the construction of quasi-equilibrium binaries with a spinning black hole.
Second, we construct binaries in low-eccentricity orbits, which are a better
approximation to astrophysical binaries than quasi-equilibrium systems.


title: On parahoric subgroups

abstract: We prove some basic facts on parahoric subgroups and on Iwahori-Weyl groups.


title: Strongly compressible current sheets under gravitation

abstract:
  Many stormy events in astrophysics occur due to the sudden magnetic energy
release. This is possible if a magnetic configuration abruptly changes its
topology, an event usually referred to as magnetic reconnection. It is known
that pure Ohmic decay is inefficient, occurring during cosmological times (due
to the huge characteristic scales $L$). It is recognized that the presence of
current sheets speeds up the process, but still insufficiently$^{1,2,3,4,5}$.
We show that, in highly compressible and substantially gravitational media, the
reconnection is fast enough to account for stormy events. Thus, highly
compressible situations offer exiting opportunities in explanations of violent
events, although full-scale compressible and gravitational simulations proved
to be quite challenging.


title: On universality of critical behaviour in Hamiltonian PDEs

abstract:
  Our main goal is the comparative study of singularities of solutions to the
systems of first order quasilinear PDEs and their perturbations containing
higher derivatives. The study is focused on the subclass of Hamiltonian PDEs
with one spatial dimension. For the systems of order one or two we describe the
local structure of singularities of a generic solution to the unperturbed
system near the point of "gradient catastrophe" in terms of standard objects of
the classical singularity theory; we argue that their perturbed companions must
be given by certain special solutions of Painleve' equations and their
generalizations.


title:
Towards Usage-based Impact Metrics: - First Results from the MESUR
  Project

abstract:
  Scholarly usage data holds the potential to be used as a tool to study the
dynamics of scholarship in real time, and to form the basis for the definition
of novel metrics of scholarly impact. However, the formal groundwork to
reliably and validly exploit usage data is lacking, and the exact nature,
meaning and applicability of usage-based metrics is poorly understood. The
MESUR project funded by the Andrew W. Mellon Foundation constitutes a
systematic effort to define, validate and cross-validate a range of usage-based
metrics of scholarly impact. MESUR has collected nearly 1 billion usage events
as well as all associated bibliographic and citation data from significant
publishers, aggregators and institutional consortia to construct a large-scale
usage data reference set. This paper describes some major challenges related to
aggregating and processing usage data, and discusses preliminary results
obtained from analyzing the MESUR reference data set. The results confirm the
intrinsic value of scholarly usage data, and support the feasibility of
reliable and valid usage-based metrics of scholarly impact.


title: Dark Matter in the Private Higgs Model

abstract:
  The extremely large hierarchy observed in the fermion mass spectrum remains
as one of the most puzzling and unresolved issues in particle physics. In a
recent proposal, however, it was demonstrated that by introducing one Higgs
doublet (or Private Higgs) per fermion this hierarchy could be made natural by
making the Yukawa couplings between each fermion and its respective Higgs boson
of order unity. Among the interesting predictions of the Private Higgs scenario
is a variety of scalars which could be probed at future collider experiments
and a possible dark matter candidate. In this paper, we study in some detail
the dark matter sector of the Private Higgs model. We first calculate the
annihilation cross sections of dark matter in this model and find that one can
easily account for the observed density of dark matter in the Universe with
relatively natural values of the model's parameters. Finally, we investigate
the possibility of detecting Private Higgs dark matter indirectly via the
observation of anomalous gamma rays originating from the galactic halo. We show
that a substantial flux of photons can be produced from the annihilation of
Private Higgs dark matter such that, if there is considerable clumping of dark
matter in the galactic halo, the flux of these gamma rays could be observed by
ground-based telescope arrays such as VERITAS and HESS.


title: Exact Statistics of Chaotic Dynamical Systems

abstract:
  We present an inverse method to construct large classes of chaotic invariant
sets together with their exact statistics. The associated dynamical systems are
characterized by a probability distribution and a two-form. While our emphasis
is on classical systems, we briefly speculate about possible applications to
quantum field theory, in the context of generalizations of stochastic
quantization.

categories: nlin.CD cond-mat.stat-mech hep-th physics.flu-dyn


title:
Abruption decay of entanglement and quantum communication through noise
  channels

abstract:
  We investigate the dynamics of two qubits state through the Bloch channel.
  It is found that the degradation and sudden-death of the entanglement depend
on the channel's parameters and the structure of the input state. Starting from
partially entangled states as input state, the output states are more robust
compared with those obtained from initial maximally entangled states. Also the
survivability of entanglement increased as the absolute equilibrium values of
the channel increased or the ratio between the longitudinal and transverse
relaxation times gets smaller. Ability of using the output states as quantum
channels to perform quantum teleportation is investigated. The idea that the
useful output states are used to achieve the original quantum teleportation
protocol is discussed.


title: Effects of Supernova Feedback on the Formation of Galaxy Disks

abstract:
  We use cosmological simulations in order to study the effects of supernova
(SN) feedback on the formation of a Milky Way-type galaxy of virial mass ~10^12
M_sun/h. We analyse a set of simulations run with the code described by
Scannapieco et al. (2005, 2006), where we have tested our star formation and
feedback prescription using isolated galaxy models. Here we extend this work by
simulating the formation of a galaxy in its proper cosmological framework,
focusing on the ability of the model to form a disk-like structure in
rotational support. We find that SN feedback plays a fundamental role in the
evolution of the simulated galaxy, efficiently regulating the star formation
activity, pressurizing the gas and generating mass-loaded galactic winds. These
processes affect several galactic properties such as final stellar mass,
morphology, angular momentum, chemical properties, and final gas and baryon
fractions. In particular, we find that our model is able to reproduce extended
disk components with high specific angular momentum and a significant fraction
of young stars. The galaxies are also found to have significant spheroids
composed almost entirely of stars formed at early times. We find that most
combinations of the input parameters yield disk-like components, although with
different sizes and thicknesses, indicating that the code can form disks
without fine-tuning the implemented physics. We also show how our model scales
to smaller systems. By analysing simulations of virial masses 10^9 M_sun/h and
10^10 M_sun/h, we find that the smaller the galaxy, the stronger the SN
feedback effects.


title: Service Cloaking and Authentication at Data Link Layer

abstract:
  This paper discusses that there is significant benefit in providing stronger
security at lower layers of the network stack for hosts connected to a network.
It claims to reduce the attack vulnerability of a networked host by providing
security mechanisms in a programmable Network Interface Card (NIC). Dynamic
access control mechanisms are implemented in hardware to restrict access to the
services provided, only to authenticated hosts. This reduces server
vulnerability to various layer 2 attacks. Also the services will be immune to
zero-day vulnerabilities due to the minimal code execution paths. To this end,
it presents architecture and implementation details of a programmable network
interface card equipped with these measures. It works alongside, and augments,
existing security protocols making deployment practical.


title: Wide-Field Chandra X-Ray Observations of AGN in Abell 85 & Abell 754

abstract:
  To better understand the mechanism or mechanisms that lead to AGN activity
today, we measure the X-ray AGN fraction in a new sample of nearby clusters and
examine how it varies with galaxy properties, projected cluster-centric radius,
and cluster velocity dispersion. We present new wide-field Chandra X-ray
Observatory observations of Abell 85, Abell 754 and the background cluster
Abell 89B out to their virial radii. Out of seventeen X-ray sources associated
with galaxies in these clusters, we classify seven as X-ray AGN with L_{X,B} >
10^{41} erg/s. Only two of these would be classified as AGN based on their
optical spectra. We combine these observations with archival data to create a
sample of X-ray AGN from six z < 0.08 clusters and find that 3.4+1.1/-0.8% of
M_R < -20 galaxies host X-ray AGN with L_{X,B} > 10^{41} erg/s. We find that
more X-ray AGN are detected in more luminous galaxies and attribute this to
larger spheriods in more luminous galaxies and increased sensitivity to lower
Eddington-rate accretion from black holes in those spheroids. At a given X-ray
luminosity limit, more massive black holes can be accreting less efficiently,
yet still be detected. If interactions between galaxies are the principal
drivers of AGN activity, then the AGN fraction should be higher in lower
velocity dispersion clusters and the outskirts of clusters. However, the
tendency of the most massive and early-type galaxies to lie in the centers of
the richest clusters could dilute such trends. While we find no variation in
the AGN fraction with projected cluster-centric radius, we do find that the AGN
fraction increases significantly from 2.6+1.0/-0.8% in rich clusters to
10.0+6.2/-4.3% in those with lower velocity dispersions.


title: Is the Sun Embedded in a Typical Interstellar Cloud?

abstract:
  The physical properties and kinematics of the partially ionized interstellar
material near the Sun are typical of warm diffuse clouds in the solar vicinity.
The interstellar magnetic field at the heliosphere and the kinematics of nearby
clouds are naturally explained in terms of the S1 superbubble shell. The
interstellar radiation field at the Sun appears to be harder than the field
ionizing ambient diffuse gas, which may be a consequence of the low opacity of
the tiny cloud surrounding the heliosphere. The spatial context of the Local
Bubble is consistent with our location in the Orion spur.


title:
Collinear source of polarization-entangled photon pairs at
  non-degenerate wavelengths

abstract:
  We report on a simple but highly efficient source of polarization-entangled
photon pairs at non-degenerate wavelengths. The fully collinear configuration
of the source enables very high coupling efficiency into a single optical mode
and allows the use of long nonlinear crystals. With optimized dispersion
compensation it is possible to use a free-running laser diode as pump source
and to reach an entanglement fidelity of 99.4 % at rates as high as 27000
pairs/s per mW of pump power. This greatly enhances the practicality of the
source for applications in quantum communication and metrology.


title:
Stability of the U(1) spin liquid with spinon Fermi surface in 2+1
  dimensions

abstract:
  We study the stability of the 2+1 dimensional U(1) spin liquid state against
proliferation of instantons in the presence of spinon Fermi surface. By mapping
the spinon Fermi surface into an infinite set of 1+1 dimensional chiral
fermions, it is argued that an instanton has an infinite scaling dimension for
any nonzero number of spinon flavors. Therefore, the spin liquid phase is
stable against instantons and the non-compact U(1) gauge theory is a good low
energy description.


title: Decay of an inhomogeneous state via resonant tunnelling

abstract:
  We recently investigated the nature of resonant tunnelling in standard scalar
Quantum Field Theory, uncovering the conditions required for resonance. It was
shown that whereas the homogeneous false vacuum may decay via bubble
nucleation, it may not decay in a resonant fashion. The no-go theorem given
there is circumvented in this study by considering an initial state other than
the homogeneous false vacuum, and we confirm our mechanism by showing in an
explicit model how resonant tunnelling occurs. Using this model we demonstrate
how the tunnelling rate depends on the energy of specially constructed initial
states, with these states corresponding to contracting spherical bubbles of
some vacuum that evolve to a minimum radius and then tunnel to another vacuum,
instead of the classical motion where the bubble would just start to expand.


title: Representations of Higher Rank Graph Algebras

abstract:
  Let $\Fth$ be a $\Bk$-graph on a single vertex. We show that every
irreducible atomic $*$-representation is the minimal $*$-dilation of a group
construction representation. It follows that every atomic representation
decomposes as a direct sum or integral of such representations. We characterize
periodicity of $\Fth$ and identify a symmetry subgroup $H_\theta$ of $\bZ^\Bk$.
If this has rank $s$, then $\ca(\Fth) \cong \rC(\bT^s) \otimes \fA$ for some
simple C*-algebra $\fA$.


title:
Coexistence of itinerant ferromagnetism and a non-unitary
  superconducting state with line nodes: possible application to UGe$_2$

abstract:
  We construct a mean-field theory for itinerant ferromagnetism coexisting with
a non-unitary superconducting state, where only the majority-spin band is
gapped and contains line nodes, while the minority-spin band is gapless at the
Fermi level. Our study is motivated by recent experimental results indicating
that this may be the physical situation realized in the heavy-fermion compound
UGe$_2$. We investigate the stability of the mean-field solution of the
magnetic and superconducting order parameters. Also, we provide theoretical
predictions for experimentally measurable properties of such a non-unitary
superconductor: the specific heat capacity, the Knight shift, and the tunneling
conductance spectra. Our study should be useful for direct comparison with
experimental results and also for further predictions of the physics that may
be expected in ferromagnetic superconductors.


title: Gravity Gets There First with Dark Matter Emulators

abstract:
  We discuss the implications for gravity wave detectors of a class of modified
gravity theories which dispense with the need for dark matter. These models,
which are known as Dark Matter Emulators, have the property that weak
gravitational waves couple to the metric that would follow from general
relativity without dark matter whereas ordinary particles couple to a
combination of the metric and other fields which reproduces the result of
general relativity with dark matter. We show that there is an appreciable
difference in the Shapiro delays of gravitational waves and photons or
neutrinos from the same source, with the gravity waves always arriving first.
We compute the expected time lags for GRB 070201, for SN 1987a, and for Sco-X1.
We estimate the probable error by taking account of the uncertainty in
position, and by using three different dark matter profiles.


title: A systematic study of direct photon production in heavy ion collisions

abstract:
  A theoretical derivation of photon bremsstrahlung, induced by the
interactions of an energetic quark in a hot and dense quark-gluon plasma, is
given in the framework of the reaction operator approach. For the physically
relevant case of hard jet production, followed by few in-medium interactions,
we find that the Landau-Pomeranchuk-Migdal suppression of the bremsstrahlung
photon intensity is much stronger than in the previously discussed limit of
on-shell quarks and a large number of soft scatterings. We present the first
systematic study of direct photon production in minimum bias d+Cu and d+Au and
central Cu+Cu and Au+Au heavy ion collisions at the Relativistic Heavy Ion
Collider at center of mass energies of 62.4 GeV and 200 GeV. We find that the
contribution of the final-state photon production at pT < 5 GeV is limited to
35%, and at high transverse momenta, the modification of the direct photon
cross section is dominated by initial-state cold nuclear matter effects.


title:
Gravito-Magnetism in one-body and two-body systems: Theory and
  Experiments

abstract:
  We survey theoretical and experimental/observational results on
general-relativistic spin (rotation) effects in binary systems. A detailed
discussion is given of the two-body Kepler problem and its first post-Newtonian
generalization, including spin effects. Spin effects result from gravitational
spin-orbit and spin-spin interactions (analogous to the corresponding case in
quantum electrodynamics) and these effects are shown to manifest themselves in
two ways: (a) precession of the spinning bodies per se and (b) precession of
the orbit (which is further broke down into precessions of the argument of the
periastron, the longitude of the ascending node and the inclination of the
orbit). We also note the ambiguity that arises from use of the terminology
frame-dragging, de Sitter precession and Lense-Thirring precession, in contrast
to the unambiguous reference to spin-orbit and spin-spin precessions. Turning
to one-body experiments, we discuss the recent results of the GP-B experiment,
the Ciufolini-Pavlis Lageos experiment and lunar-laser ranging measurements
(which actually involve three bodies). Two-body systems inevitably involve
astronomical observations and we survey results obtained from the first binary
pulsar system, a more recently discovered binary system and, finally, the
highly significant discovery of a double-pulsar binary system.


title: How to build nanoblocks using DNA scaffolds

abstract:
  In recent years there have been a number of proposals to utilize the
specificity of DNA based interactions for potential applications in
nanoscience. One interesting direction is the self-assembly of micro- and
nanoparticle clusters using DNA scaffolds. In this letter we consider a DNA
scaffold method to self-assemble clusters of "colored" particles. Stable
clusters of microspheres have recently been produced by an entirely different
method. Our DNA based approach self-assembles clusters with additional degrees
of freedom associated with particle permutation. We demonstrate that in the
non-equilibrium regime of irreversible binding the self-assembly process is
experimentally feasible. These color degrees of freedom may allow for more
diverse intercluster interactions essential for hierarchical self-assembly of
larger structures.


title: Non-Maxwellian Proton Velocity Distributions in Nonradiative Shocks

abstract:
  The Balmer line profiles of nonradiative supernova remnant shocks provide the
means to measure the post-shock proton velocity distribution. While most
analyses assume a Maxwellian velocity distribution, this is unlikely to be
correct. In particular, neutral atoms that pass through the shock and become
ionized downstream form a nonthermal distribution similar to that of pickup
ions in the solar wind. We predict the H alpha line profiles from the
combination of pickup protons and the ordinary shocked protons, and we consider
the extent to which this distribution could affect the shock parameters derived
from H alpha profiles. The Maxwellian assumption could lead to an underestimate
of shock speed by up to about 15%. The isotropization of the pickup ion
population generates wave energy, and we find that for the most favorable
parameters this energy could significantly heat the thermal particles.
Sufficiently accurate profiles could constrain the strength and direction of
the magnetic field in the shocked plasma, and we discuss the distortions from a
Gaussian profile to be expected in Tycho's supernova remnant.


title: Finite size scaling of meson propagators with isospin chemical potential

abstract:
  We determine the volume and mass dependence of scalar and pseudoscalar
two-point functions in N_f-flavour QCD, in the presence of an isospin chemical
potential and at fixed gauge-field topology. We obtain these results at second
order in the \epsilon-expansion of Chiral Perturbation Theory and evaluate all
relevant zero-mode group integrals analytically. The virtue of working with a
non-vanishing chemical potential is that it provides the correlation functions
with a dependence on both the chiral condensate, \Sigma, and the pion decay
constant, F, already at leading order. Our results may therefore be useful for
improving the determination of these constants from lattice QCD calculations.
As a side product, we rectify an earlier calculation of the O(\epsilon^2)
finite-volume correction to the decay constant appearing in the partition
function. We also compute a generalised partition function which is useful for
evaluating U(N_f) group integrals.


title: Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey

abstract:
  We identify seven new ultracool white dwarfs discovered in the Sloan Digital
Sky Survey (SDSS). The SDSS photometry, spectra, and proper motions are
presented, and additional BVRI data are given for these and other previously
discovered ultracool white dwarfs. The observed colors span a remarkably wide
range, qualitatively similar to colors predicted by models for very cool white
dwarfs. One of the new stars (SDSS J1251+44) exhibits strong collision-induced
absorption (CIA) in its spectra, while the spectra and colors of the other six
are consistent with mild CIA. Another of the new discoveries (SDSS J2239+00A)
is part of a binary system -- its companion is also a cool white dwarf, and
other data indicate that the companion exhibits an infrared flux deficiency,
making this the first binary system composed of two CIA white dwarfs. A third
discovery (SDSS J0310-00) has weak Balmer emission lines. The proper motions of
all seven stars are consistent with membership in the disk or thick disk.


title: The Entropy Function for the extremal Kerr-(anti-)de Sitter Black Holes

abstract:
  Based on the entropy function formalism, we consider the extremal
Kerr-(anti-)de Sitter black holes in 4-dimensions. Solving differential
equations exactly, which are obtained by extremizing the entropy function, we
find agreement of the result with Bekenstein-Hawking entropy. Concerning the
higher derivative corrections, we extend the computation to the case with
Gauss-Bonnet term.


title: Dwarf Spheroidals in MOND

abstract:
  We take the line of sight velocity dispersions as functions of radius for 8
Milky Way dwarf spheroidal galaxies and use Jeans analysis to calculate the
mass-to-light ratios (M/L) in Modified Newtonian Dynamics (MOND). Using the
latest structural parameters, distances and variable velocity anisotropy, we
find 6/8 dwarfs have sensible M/L using only the stellar populations. Sextans
and Draco, however, have M/L=9.2_{-3.0}^{+5.3} and 43.9_{-19.3}^{+29.0}
respectively, which poses a problem. Apart from the need for Sextans'
integrated magnitude to be reviewed, we propose tidal effects intrinsic to
MOND, testable with numerical simulations, but fully orbit dependant, which are
disrupting Draco. The creation of the Magellanic Stream is also re-addressed in
MOND, the scenario being the stream is ram pressure stripped from the SMC as it
crosses the LMC.


title: Mutation of cluster-tilting objects and potentials

abstract:
  We prove that mutation of cluster-tilting objects in triangulated
2-Calabi-Yau categories is closely connected with mutation of quivers with
potentials. This gives a close connection between 2-CY-tilted algebras and
Jacobian algebras associated with quivers with potentials.
  We show that cluster-tilted algebras are Jacobian and also that they are
determined by their quivers. There are similar results when dealing with
tilting modules over 3-CY algebras. The nearly Morita equivalence for
2-CY-tilted algebras is shown to hold for the finite length modules over
Jacobian algebras.


title: Link Enhancer for Vehicular Wireless ATM Communications

abstract:
  Majority of the applications used in defense are voice, video and data
oriented and has strict QoS requirements. One of the technologies that enabled
this is Asynchronous Transfer Mode (ATM) networking. Traditional ATM networks
are wired networks. But Tactical networks are meant to be mobile and this
necessitates the use of radio relays for Vehicle-to-Infrastructure (V2I) and
Vehicle-to-Vehicle (V2V) communications. ATM networks assume a physical link
layer BER of 10^-9 or better because of the availability of reliable media like
optical fiber links. But this assumption is no longer valid when ATM switches
are connected through radio relay where error rates are in the rage of 10^-3.
This paper presents the architecture of a Link Enhancer meant to improve the
Bit Error Rate of the Wireless links used for V2I and V2V communications from 1
in 10^4 to 1 in 10^8


title: Nuclear Electric Dipole Moment of 3He

abstract:
  A permanent electric dipole moment (EDM) of a physical system requires
time-reversal (T) and parity (P) violation. Experimental programs are currently
pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of
fundamental theoretical interest. Here we calculate the magnitude of the
PT-violating EDM of 3He and the expected sensitivity of such a measurement to
the underlying PT-violating interactions. Assuming that the coupling constants
are of comparable magnitude for pi-, rho-, and omega-exchanges, we find that
the pion-exchange contribution dominates. Our results suggest that a
measurement of the 3He EDM is complementary to the planned neutron and deuteron
experiments, and could provide a powerful constraint for the theoretical models
of the pion-nucleon PT-violating interaction.


title: Invariance of Gromov--Witten theory under a simple flop

abstract:
  We show that the generating functions of Gromov--Witten invariants with
ancestors are invariant under a simple flop, for all genera, after an analytic
continuation in the extended K\"ahler moduli space. This is a sequel to [LLW].


title: Multiple Random Oracles Are Better Than One

abstract:
  We study the problem of learning k-juntas given access to examples drawn from
a number of different product distributions. Thus we wish to learn a function f
: {-1,1}^n -> {-1,1} that depends on k (unknown) coordinates. While the best
known algorithms for the general problem of learning a k-junta require running
time of n^k * poly(n,2^k), we show that given access to k different product
distributions with biases separated by \gamma>0, the functions may be learned
in time poly(n,2^k,\gamma^{-k}). More generally, given access to t <= k
different product distributions, the functions may be learned in time n^{k/t} *
poly(n,2^k,\gamma^{-k}). Our techniques involve novel results in Fourier
analysis relating Fourier expansions with respect to different biases and a
generalization of Russo's formula.


title: A Theory for Market Impact: How Order Flow Affects Stock Price

abstract:
  It is known that the impact of transactions on stock price (market impact) is
a concave function of the size of the order, but there exists little
quantitative theory that suggests why this is so. I develop a quantitative
theory for the market impact of hidden orders (orders that reflect the true
intention of buying and selling) that matches the empirically measured result
and that reproduces some of the non-trivial and universal properties of stock
returns (returns are percent changes in stock price). The theory is based on a
simple premise, that the stock market can be modeled in a mechanical way - as a
device that translates order flow into an uncorrelated price stream. Given that
order flow is highly autocorrelated, this premise requires that market impact
(1) depends on past order flow and (2) is asymmetric for buying and selling. I
derive the specific form for the dependence in (1) by assuming that current
liquidity responds to information about all currently active hidden orders
(liquidity is a measure of the price response to a transaction of a given
size). This produces an equation that suggests market impact should scale
logarithmically with total order size. Using data from the London Stock
Exchange I empirically measure market impact and show that the result matches
the theory. Also using empirical data, I qualitatively specify the asymmetry of
(2). Putting all results together, I form a model for market impact that
reproduces three universal properties of stock returns - that returns are
uncorrelated, that returns are distributed with a power law tail, and that the
magnitude of returns is highly autocorrelated (also known as clustered
volatility).


title:
HST/ACS Observations of Star Formation Driven Outflows in Nearby Edge-on
  Spiral Galaxies: Dependence of Halo Morphology on Star Formation Activity

abstract:
  (Abridged). We present new high spatial resolution narrowband imaging
observations of extraplanar diffuse ionized gas (eDIG) in four late-type,
actively star forming edge-on spirals, obtained with ACS on-board HST. Our
F658N (H-alpha) observations reveal a multitude of structures on both small and
large scales. Whereas all four galaxies have been studied with ground-based
telescopes before, here the small scale structure of the extended emission line
gas is presented for the first time at a spatial resolution of 0.05",
corresponding to 5.0 pc at the mean distance to the target galaxies. The eDIG
morphology is very different for all four targets, probably as a result of
their different levels of star formation activity. We find that the morphology
of the eDIG, in particular the break-up of diffuse emission into filaments in
galaxy halos, shows a strong dependence on the level of star formation activity
per unit area, and eDIG can be arranged into a morphological sequence. NGC4634
and NGC5775 have the highest SF rate per unit area in our sample and the
observed morphology suggests that the break-up of the smooth eDIG layer into
individual resolved filaments occurs only above a certain threshold of SF
activity per unit area. Combined with ground-based data for samples that span a
larger range of galaxy mass our results indicate that the gravitational
potential also plays an important role in the eDIG morphology. In low-mass
galaxies the gas can be expelled due to shallow gravitational potentials more
easily and couple with strong star formation driven outflows on a local scale.
This is in contrast to the more massive galaxies, which show smooth eDIG
layers, unless they are powered by a superwind, as in the case of nucleated
starburst galaxies.


title: Confined gravitational waves for chiral matter with heat

abstract:
  The GR wave self-heating of geodesic massive bodies with constant
thermo-gravimechanical energies increases the brightness-to-charge ratio along
spiral radial transitions in the energy-to-energy gravitation. Paired confined
gravitons locally warm accelerated matter that suggests the thermodynamical
origin of electromagnetic outbursts with oscillating Wien's displacements.
Damping of orbital periods by chiral GR waves is more efficient for neutron
stars around giant companions than for binary pulsars.


title: Fourier expansions for the potentials of lattices of charge

abstract:
  We apply the Poisson sum rule to obtain formal expressions for the Fourier
coefficients of the potential of a lattice of generalized charge. Each
generalized charge is assumed to contribute to the potential a term which
depends only on the vector displacement from the charge's location. The
coefficients are explicitly calculated for Coulomb and Yukawa-type individual
particle potentials. The potentials of finite and disordered lattices are also
briefly considered.


title: Interaction cohomology of forward or backward self-similar systems

abstract:
  We investigate the dynamics of forward or backward self-similar systems
(iterated function systems) and the topological structure of their invariant
sets. We define a new cohomology theory (interaction cohomology) for forward or
backward self-similar systems. We show that under certain conditions, the space
of connected components of the invariant set is isomorphic to the inverse limit
of the spaces of connected components of the realizations of the nerves of
finite coverings${\cal U} $ of the invariant set, where each ${\cal U}$
consists of (backward)images of the invariant set under elements of finite word
length. Inparticular, we give a criterion for the invariant set to be
connected. Moreover, we give a sufficient condition for the first cohomology
group to have infinite rank. As an application, we obtain many results on the
dynamics of finitely generated semigroups of polynomials on the complex plane.
Moreover, we define postunbranched systems and we investigate the interaction
cohomology groups of such systems. Many examples are given.


title:
A Global Stability Analysis of Clusters of Galaxies with Conduction and
  AGN Feedback Heating

abstract:
  We investigate a series of steady-state models of galaxy clusters, in which
the hot intracluster gas is efficiently heated by active galactic nucleus (AGN)
feedback and thermal conduction, and in which the mass accretion rates are
highly reduced compared to those predicted by the standard cooling flow models.
We perform a global Lagrangian stability analysis. We show for the first time
that the global radial instability in cool core clusters can be suppressed by
the AGN feedback mechanism, provided that the feedback efficiency exceeds a
critical lower limit. Furthermore, our analysis naturally shows that the
clusters can exist in two distinct forms. Globally stable clusters are expected
to have either: 1) cool cores stabilized by both AGN feedback and conduction,
or 2) non-cool cores stabilized primarily by conduction. Intermediate central
temperatures typically lead to globally unstable solutions. This bimodality is
consistent with the recently observed anticorrelation between the flatness of
the temperature profiles and the AGN activity (Dunn & Fabian 2008) and the
observation by Rafferty et al. (2008) that the shorter central cooling times
tend to correspond to significantly younger AGN X-ray cavities.


title:
Regular second order perturbations of binary black holes: The extreme
  mass ratio regime

abstract:
  In order to derive the precise gravitational waveforms for extreme mass ratio
inspirals (EMRI), we develop a formulation for the second order metric
perturbations produced by a point particle moving in the Schwarzschild
spacetime. The second order waveforms satisfy a wave equation with an effective
source build up from products of the first order perturbations and its
derivatives. We have explicitly regularized this source at the horizon and at
spatial infinity. We show that the effective source does not contain squares of
the Dirac's delta and that perturbations are regular at the particle location.
We introduce an asymptotically flat gauge for the radiation fields and the
$\ell=0$ mode to compute explicitly the (leading) second order $\ell=2$
waveforms in the headon collision case. This case represents the first
completion of the radiation reaction program self-consistently.


title:
On the inner and outer bounds for 2-receiver discrete memoryless
  broadcast channels

abstract:
  We study the best known general inner bound[MAR '79] and outer bound[N-EG'07]
for the capacity region of the two user discrete memory less channel. We prove
that a seemingly stronger outer bound is identical to a weaker form of the
outer bound that was also presented in [N-EG'07]. We are able to further
express the best outer bound in a form that is computable, i.e. there are
bounds on the cardinalities of the auxiliary random variables.
  The inner and outer bounds coincide for all channels for which the capacity
region is known and it is not known whether the regions described by these
bounds are same or different. We present a channel, where assuming a certain
conjecture backed by simulations and partial theoretical results, one can show
that the bounds are different.


title: Radiotherapy using a laser proton accelerator

abstract:
  Laser acceleration promises innovation in particle beam therapy of cancer
where an ultra-compact accelerator system for cancer beam therapy can become
affordable to a broad range of patients. This is not feasible without the
introduction of a technology that is radically different from the conventional
accelerator-based approach. The laser acceleration method provides many
enhanced capabilities for the radiation oncologist. It reduces the overall
system size and weight by more than one order of magnitude. The characteristics
of the particle beams (protons) make them suitable for a class of therapy that
might not be possible with the conventional accelerator, such as the ease for
changing pulse intensity, the focus spread, the pinpointedness, and the dose
delivery in general. A compact, uncluttered system allows a PET device to be
located in the vicinity of the patient in concert with the compact gantry. The
radiation oncologist may be able to irradiate a localized tumor by scanning
with a pencil-like particle beam while ascertaining the actual dosage in the
patient with an improved in-beam PET verification of auto-radioactivation
induced by the beam therapy. This should yield an unprecedented flexibility in
the feedback radiotherapy by the radiation oncologist. Laser accelerated
radiotherapy has a unique niche in a current world of high energy accelerator
using synchrotron or cyclotron.


title: Inverse Temperature 4-vector in Special Relativity

abstract:
  There exist several prescriptions for identifying the notion of temperature
in special relativity. We argue that the inverse temperature 4-vector $\bf
\beta$ is the only viable option from the laws of thermodynamics, and $\bf
\beta$ is a future-directed timelike 4-vector. Using a superfluidity thought
experiment, one can show that $\bf \beta$ is not necessarily along the time
direction of the comoving frame of the system, as is usually thought. It is
conjectured that, for an isolated system, the 4-vector is determined from the
entropy-maximum principle.


title: A deconvolution estimate and localization in spline-type spaces

abstract:
  In this article some explicit estimates on the decay of the convolutive
inverse of a sequence are proved. They are derived from the functional calculus
for Sobolev algebras. Applications include localization in spline-type spaces
and oversampling schemes.


title:
Revisiting the parametrization of Equation of State of Dark Energy via
  SNIa Data

abstract:
  In this paper, we revisit the parameterizations of the equation of state of
dark energy and point out that comparing merely the $\chi^2$ of different
fittings may not be optimal for choosing the "best" parametrization. Another
figure of merit for evaluating different parametrizations based on the area of
the $w(z) - z$ band is proposed. In light of the analysis of some two-parameter
parameterizations and models based on available SNIa data, the area of $w(z)-z$
band seems to be a good figure of merit, especially in the situation that the
value of $\chi^2_{\rm min}$ for different parametrizations are very close.
Therefore, we argue that both the area of the $w(z)-z$ band and $\chi^2_{\rm
min}$ should be synthetically considered for choosing a better parametrization
of dark energy in the future experiments.


title:
The concrete theory of numbers : New Mersenne conjectures. Simplicity
  and other wonderful properties of numbers $L(n) = 2^{2n}\pm2^n\pm1$

abstract:
  New Mersenne conjectures. The problems of simplicity, common prime divisors
and free from squares of numbers $L(n) = 2^{2n}\pm2^n\pm1$ are investigated.
Wonderful formulas $gcd $ for numbers $L (n) $ and numbers repunit are proved.


title: The Kerr black hole and rotating black string by intersecting M-branes

abstract:
  We construct the non-BPS black brane representation from the Kerr metric
using the U-duality and symmetries in string or M-theory. We give the general
rule to get the brane configuration and we apply it especially for Kerr metric.
We find the three charged solution in M-theory and after the compactification
it becomes rotating black string solution in five dimension. We also find the
four charged solution containing the pp-wave in M-theory, and we can find
charged dilaton rotating black hole solution in four dimension after the torus
compactification. This solution has the other representation in string theory,
which is easy to apply the AdS/CFT correspondence.


title: Modelling Magnetic Fluctuations in the Stripe Ordered State

abstract:
  The nature of the interplay between superconductivity and magnetism in the
cuprates remains one of the fundamental unsolved problems in high temperature
superconductivity. Whether and how these two phenomena are interdependent is
perhaps most sharply seen in the stripe phases of various copper-oxide
materials. These phases, involving a mixture of spin and charge density waves,
do not yet admit a complete, overarching theoretical treatment. However aspects
of this problem can be analyzed. In this work, we focus on the magnetic side of
stripe physics. To this end, we study a simple model of a stripe-ordered phase
consisting of an array of alternating coupled doped and undoped two-leg
Hubbard-like ladders. To obtain the magnetic response, we employ already
available dynamical susceptibilities of the individual two-leg ladders and
treat the interladder coupling in a random phase approximation. Strikingly, we
find two possible scenarios for the ordered state induced by the coupling
between ladders: the spin modulation can occur either along or perpendicular to
the direction of the stripes. These two scenarios are differentiated according
to different microscopic realizations of the component doped ladders. However
inelastic neutron scattering experiments on the two stripe ordered cuprates,
La_{1.875}Ba_{0.125}CuO_4 and La_{2-x}Sr_xCuO_4, do not readily distinguish
between these two scenarios due to manner in which stripes form in these
materials.


title:
Interaction of Dirac and Majorana Neutrinos with Weak Gravitational
  Fields

abstract:
  In this paper the interaction of high energy neutrinos with weak
gravitational fields is briefly explored. The form of the graviton-neutrino
vertex is motivated from Lorentz and gauge invariance and the non-relativistic
interpretations of the neutrino gravitational form factors are obtained. We
comment on the renormalization conditions, the preservation of the weak
equivalence principle and the definition of the neutrino mass radius. We
associate the neutrino gravitational form factors with specific angular
momentum states. Based on Feynman diagrams, spin-statistics, CP invariance and
symmetries of the angular momentum states in the neutrino-graviton vertex, we
deduce differences between the Majorana and Dirac cases. It is then proved that
in spite of the theoretical differences between the two cases, as far as
experiments are considered, they would be virtually indistinguishable for any
space-time geometry satisfying the weak field condition. We then calculate the
transition gravitational form factors for the neutrino by evaluating the
relevant Feynman diagrams at 1-loop and estimate a neutrino transition mass
radius. The form factor is seen to depend on the momentum transfer very weakly.
It is also seen that the neutrino transition mass radius is smaller than the
typical neutrino charge radius by a couple of orders of magnitude.


title: Dynamical Properties of the $\sigma$ Meson

abstract:
  Studies on the dynamical properties of the $\sigma$ meson are reviewed and
discussed. The important role of fundamental principles such as analyticity,
unitarity and crossing symmetry played in the studies are stressed.


title:
A Quasi-Newton Approach to Nonsmooth Convex Optimization Problems in
  Machine Learning

abstract:
  We extend the well-known BFGS quasi-Newton method and its memory-limited
variant LBFGS to the optimization of nonsmooth convex objectives. This is done
in a rigorous fashion by generalizing three components of BFGS to
subdifferentials: the local quadratic model, the identification of a descent
direction, and the Wolfe line search conditions. We prove that under some
technical conditions, the resulting subBFGS algorithm is globally convergent in
objective function value. We apply its memory-limited variant (subLBFGS) to
L_2-regularized risk minimization with the binary hinge loss. To extend our
algorithm to the multiclass and multilabel settings, we develop a new,
efficient, exact line search algorithm. We prove its worst-case time complexity
bounds, and show that our line search can also be used to extend a recently
developed bundle method to the multiclass and multilabel settings. We also
apply the direction-finding component of our algorithm to L_1-regularized risk
minimization with logistic loss. In all these contexts our methods perform
comparable to or better than specialized state-of-the-art solvers on a number
of publicly available datasets. An open source implementation of our algorithms
is freely available.


title:
Numeric Experiments in Relativistic Thermodynamics: A Moving System
  Appears Cooler

abstract:
  In this paper we simulate a two dimensional relativistic ideal gas by
implementing a relativistic elastic binary collision algorithm. We show that
the relativistic gas faithfully obeys J\"uttner's speed distribution function.
Furthermore, using this numeric simulation in conjunction with the energy
equipartition theorem for a relativistic gas, we conclude that a moving system
appears cooler.


title: Coulomb gauge approach to scalar hadrons

abstract:
  The Coulomb gauge model, involving an effective QCD Hamiltonian in the
Coulomb gauge, is applied to scalar hadrons. Mass predictions are presented for
both conventional q-qbar meson and q-qbar-q-qbar tetra-quark states. Mixing
matrix elements between these states were also computed and diagonalized to
provide a reasonable description of the scalar spectrum below 2 GeV.


title: Multi-frequency integrated profiles of pulsars

abstract:
  We have observed a total of 67 pulsars at five frequencies ranging from 243
to 3100 MHz. Observations at the lower frequencies were made at the Giant Metre
Wave Telescope in India and those at higher frequencies at the Parkes Telescope
in Australia. We present profiles from 34 of the sample with the best signal to
noise ratio and the least scattering. The general `rules' of pulsar profiles
are seen in the data; profiles get narrower, the polarization fraction declines
and outer components become more prominent as the frequency increases. Many
counterexamples to these rules are also observed, and pulsars with complex
profiles are especially prone to rule breaking. We hypothesise that the
location of pulsar emission within the magnetosphere evolves with time as the
the pulsar spins down. In highly energetic pulsars, the emission comes from a
confined range of high altitudes, in the middle range of spin down energies the
emission occurs over a wide range of altitudes whereas in pulsars with low
spin-down energies it is confined to low down in the magnetosphere.


title: Accelerating a Black Hole in Higher Dimensions

abstract:
  Utilising the master equation with source for perturbations of the
Schwarzschild-Tangherlini solution, we construct perturbative solutions
representing a black hole accelerated by a string in higher dimensions. We show
that such solutions can be uniquely determined by a single function
representing the local tension of the string, under natural asymptotic and
regularity conditions. We further study whether we can construct a localised
braneworld black hole solution from such a solution by cutting off a region
containing the string by a hypersurface and putting a vacuum brane on the
boundary. We find that the solution corresponding to the string with constant
tension does not allow such brane configuration when the bulk spacetime
dimension is greater than four, in contrast to the four dimensional case.
Further, we show that there exist infinitely many localised braneworld black
hole solutions in the perturbative sense for four-dimensional bulk spacetime,
if we allow non-uniform string tensions.


title:
Perturbations of Matter Fields in the Second-order Gauge-invariant
  Cosmological Perturbation Theory

abstract:
  Some formulae for the perturbations of the matter fields are summarized
within the framework of the second-order gauge-invariant cosmological
perturbation theory in a four dimensional homogeneous isotropic universe, which
is developed in the papers [K.Nakamura, Prog.Theor.Phys., 117 (2007), 17.]. We
derive the formulae for the perturbations of the energy momentum tensors and
equations of motion for a perfect fluid, an imperfect fluid, and a signle
scalar field, and show that all equations are derived in terms of
gauge-invariant variables without any gauge fixing.


title:
A binomial-coefficient identity arising from the middle discrete series
  of SU(2,2)

abstract:
  The aim of this paper is to give an elementary proof of certain identities on
binomials and state an answer to Remark 8.2 in Takahiro Hayata, Harutaka
Koseki, and Takayuki Oda, Matrix coefficients of the middle discrete series of
SU(2,2), J. Funct. Anal. 185 (2001), 297-341.


title: Rosen-Zener interferometry with Ultracold Atoms

abstract:
  We propose a time-domain "interferometer" based on ultracold Bose atoms
loaded on a double well potential. By the adiabatic Rosen-Zener process, the
barrier between two wells is ramped down slowly, held for a while, then ramped
back. Starting with a coherent state of double well system, the final
occupations on one well show interesting interference fringes in the
time-domain. The fringe pattern is sensitive to the initial state, the
interatomic interaction, and the external forces such as gravity which can
change the shape of the double well. In this sense, this interferometric scheme
has the potentials for precision measurements with ultracold atoms. The
underlying mechanism is revealed and possible applications are discussed.


title: Theory of Electron Nematic Order in LaOFeAs

abstract:
  We study a spin $S$ quantum Heisenberg model on the Fe lattice of the
rare-earth oxypnictide superconductors. Using both large $S$ and large $N$
methods, we show that this model exhibits a sequence of two phase transitions:
from a high temperature symmetric phase to a narrow region of intermediate
``nematic'' phase, and then to a low temperature spin ordered phase.
Identifying phases by their broken symmetries, these phases correspond
precisely to the sequence of structural (tetragonal to monoclinic) and magnetic
transitions that have been recently revealed in neutron scattering studies of
LaOFeAs. The structural transition can thus be identified with the existence of
incipient (``fluctuating'') magnetic order.


title: A quantitative Mean Ergodic Theorem for uniformly convex Banach spaces

abstract:
  We provide an explicit uniform bound on the local stability of ergodic
averages in uniformly convex Banach spaces. Our result can also be viewed as a
finitary version in the sense of T. Tao of the Mean Ergodic Theorem for such
spaces and so generalizes similar results obtained for Hilbert spaces by
Avigad, Gerhardy and Towsner (arXiv:0706.1512v2 [math.DS]) and T. Tao
(arXiv:0707.1117v1 [math.DS]).


title: Bounces/Dyons in the Plane Wave Matrix Model and SU(N) Yang-Mills Theory

abstract:
  We consider SU(N) Yang-Mills theory on the space R^1\times S^3 with Minkowski
signature (-+++). The condition of SO(4)-invariance imposed on gauge fields
yields a bosonic matrix model which is a consistent truncation of the plane
wave matrix model. For matrices parametrized by a scalar \phi, the Yang-Mills
equations are reduced to the equation of a particle moving in the double-well
potential. The classical solution is a bounce, i.e. a particle which begins at
the saddle point \phi=0 of the potential, bounces off the potential wall and
returns to \phi=0. The gauge field tensor components parametrized by \phi are
smooth and for finite time both electric and magnetic fields are nonvanishing.
The energy density of this non-Abelian dyon configuration does not depend on
coordinates of R^1\times S^3 and the total energy is proportional to the
inverse radius of S^3. We also describe similar bounce dyon solutions in SU(N)
Yang-Mills theory on the space R^1\times S^2 with signature (-++). Their energy
is proportional to the square of the inverse radius of S^2. From the viewpoint
of Yang-Mills theory on R^{1,1}\times S^2 these solutions describe non-Abelian
(dyonic) flux tubes extended along the x^3-axis.


title:
Automorphisms of real rational surfaces and weighted blow-up
  singularities

abstract:
  Let X be a singular real rational surface obtained from a smooth real
rational surface by performing weighted blow-ups. Denote by Aut(X) the group of
algebraic automorphisms of X into itself. Let n be a natural integer and let
e=[e_1,...,e_l] be a partition of n. Denote by X^e the set of l-tuples
(P_1,...,P_l) of distinct nonsingular curvilinear infinitely near points of X
of orders (e_1,...,e_l). We show that the group Aut(X) acts transitively on
X^e. This statement generalizes earlier work where the case of the trivial
partition e=[1,...,1] was treated under the supplementary condition that X is
nonsingular. As an application we classify singular real rational surfaces
obtained from nonsingular surfaces by performing weighted blow-ups.


title:
Cylindrical Cloak with Axial Permittivity/Permeability Spatially
  Invariant

abstract:
  In order to reduce the difficulties in the experimental realizations of the
cloak but still keep good performance of invisibility, we proposed a perfect
cylindrical invisibility cloak with spatially invariant axial material
parameters. The advantage of this kind of TE (or TM) cloak is that only rho and
phi components of mu (or epsilon) are spatially variant, which makes it
possible to realize perfect invisibility with two-dimensional (2D) magnetic (or
electric) metamaterials. The effects of perturbations of the parameters on the
performance of this cloak are quantitatively analyzed by scattering theory. Our
work provides a simple and feasible solution to the experimental realization of
cloaks with ideal parameters.


title:
Can electro-magnetic field, anisotropic source and varying $\Lambda$ be
  sufficient to produce wormhole spacetime ?

abstract:
  It is well known that solutions of general relativity which allow for
traversable wormholes require the existence of exotic matter (matter that
violates weak or null energy conditions [WEC or NEC]). In this article, we
provide a class of exact solution for Einstein-Maxwell field equations
describing wormholes assuming the erstwhile cosmological term $\Lambda$ to be
space variable, viz., $\Lambda = \Lambda (r)$.
  The source considered here not only a matter entirely but a sum of matters
i.e. anisotropic matter distribution, electromagnetic field and cosmological
constant whose effective parts obey all energy conditions out side the wormhole
throat. Here violation of energy conditions can be compensated by varying
cosmological constant. The important feature of this article is that one can
get wormhole structure, at least theoretically, comprising with physically
acceptable matters.


title:
Search for $\beta^+$EC and ECEC processes in $^{112}$Sn and
  $\beta^-\beta^-$ decay of $^{124}$Sn to the excited states of $^{124}$Te

abstract:
  Limits on $\beta^+$EC and ECEC processes in $^{112}$Sn and on
$\beta^-\beta^-$ decay of $^{124}$Sn to the excited states of $^{124}$Te have
been obtained using a 380 cm$^3$ HPGe detector and an external source
consisting of natural tin. A limit with 90% C.L. on the $^{112}$Sn half-life of
$0.92\times 10^{20}$ y for the ECEC(0$\nu$) transition to the $0^+_3$ excited
state in $^{112}$Cd (1871.0 keV) has been established. This transition is
discussed in the context of a possible enhancement of the decay rate by several
orders of magnitude given that the ECEC$(0\nu)$ process is nearly degenerate
with an excited state in the daughter nuclide. Prospects for investigating such
a process in future experiments are discussed. The $\beta^-\beta^-$ decay
limits for $^{124}$Sn to the excited states of $^{124}$Te were obtained on the
level of $(0.8-1.2)\times 10^{21}$ y at the 90% C.L.


title: The Milky Way Tomography with SDSS: II. Stellar Metallicity

abstract:
  Using effective temperature and metallicity derived from SDSS spectra for
~60,000 F and G type main sequence stars (0.2<g-r<0.6), we develop polynomial
models for estimating these parameters from the SDSS u-g and g-r colors. We
apply this method to SDSS photometric data for about 2 million F/G stars and
measure the unbiased metallicity distribution for a complete volume-limited
sample of stars at distances between 500 pc and 8 kpc. The metallicity
distribution can be exquisitely modeled using two components with a spatially
varying number ratio, that correspond to disk and halo. The two components also
possess the kinematics expected for disk and halo stars. The metallicity of the
halo component is spatially invariant, while the median disk metallicity
smoothly decreases with distance from the Galactic plane from -0.6 at 500 pc to
-0.8 beyond several kpc. The absence of a correlation between metallicity and
kinematics for disk stars is in a conflict with the traditional decomposition
in terms of thin and thick disks. We detect coherent substructures in the
kinematics--metallicity space, such as the Monoceros stream, which rotates
faster than the LSR, and has a median metallicity of [Fe/H]=-0.96, with an rms
scatter of only ~0.15 dex. We extrapolate our results to the performance
expected from the Large Synoptic Survey Telescope (LSST) and estimate that the
LSST will obtain metallicity measurements accurate to 0.2 dex or better, with
proper motion measurements accurate to ~0.2 mas/yr, for about 200 million F/G
dwarf stars within a distance limit of ~100 kpc (g<23.5). [abridged]


title: The real quadrangle of type E6

abstract:
  We give a geometric interpretation of the building associated to the real Lie
group E_6(-14) in terms of its 54-dimensional module.


title:
Conical thin shell wormhole from global monopole: A theoretical
  construction

abstract:
  By applying 'Darmois-Israel formalism', we establish a new class of thin
shell wormhole in the context of global monopole resulting from the breaking of
a global O(3) symmetry. Since global monopole is asymptotically conical (no
longer asymptotically flat), we call it as conical thin shell wormhole.
Different characteristics of this conical thin shell wormhole, namely, time
evolution of the throat, stability, total amount of exotic matter have been
discussed.


title:
Modelling coloured residual noise in gravitational-wave signal
  processing

abstract:
  We introduce a signal processing model for signals in non-white noise, where
the exact noise spectrum is a priori unknown. The model is based on a Student's
t distribution and constitutes a natural generalization of the widely used
normal (Gaussian) model. This way, it allows for uncertainty in the noise
spectrum, or more generally is also able to accommodate outliers (heavy-tailed
noise) in the data. Examples are given pertaining to data from gravitational
wave detectors.