title:
Trilinear Anomalous Gauge Interactions from Intersecting Branes and the
  Neutral Currents Sector

abstract:
  We present a study of the trilinear gauge interactions in extensions of the
Standard Model (SM) with several anomalous extra U(1)'s, identified in various
constructions, from special vacua of string theory to large extra dimensions.
In these models an axion and generalized Chern-Simons interactions for
anomalies cancelation are present. We derive generalized Ward identities for
these vertices and discuss their structure in the Stuckelberg and
Higgs-Stuckelberg phases. We give their explicit expressions in all the
relevant cases, which can be used for phenomenological studies of these models
at the LHC.


title: Achieving the Neel state in an optical lattice

abstract:
  We theoretically study the possibility of reaching the antiferromagnetic
phase of the Hubbard model by starting from a normal gas of trapped fermionic
atoms and adiabatically ramping up an optical lattice. Requirements on the
initial temperature and the number of atoms are determined for a three
dimensional square lattice by evaluating the Neel state entropy, taking into
account fluctuations around the mean-field solution. We find that these
fluctuations place important limitations on adiabatically reaching the Neel
state.


title: Stages of Homogeneous Nucleation in Solid Isotopic Helium Mixtures

abstract:
  We have made pressure and NMR measurements during the evolution of phase
separation in solid helium isotopic mixtures. Our observations indicate clearly
all three stages of the homogeneous nucleation - growth process: 1) creation of
nucleation sites; 2) growth of the new-phase component at these nucleation
sites; and 3) coarsening: the dissolution of sub-critical droplets with the
consequent further late-stage growth of the super-critical droplets. The time
exponent for the coarsening, a = 1/3, is consistent with the conserved order
parameter Lifshitz-Slezov evaporation-condensation mechanism.


title: Spin dynamics triggered by sub-terahertz magnetic field pulses

abstract:
  Current pulses of up to 20 A and as short as 3 ps are generated by a low
temperature grown GaAs (lt-GaAs) photoconductive switch and guided through a
coplanar waveguide, resulting in a 0.6 Tesla terahertz (THz) magnetic field
pulse. The pulse length is directly calibrated using photocurrent
autocorrelation. Magnetic excitations in Fe microstructures are studied by
time-resolved Kerr spectroscopy and compared with micromagnetic simulations. A
response within less than 10 ps to the THz electromagnetic field pulse is
found.


title:
Absorption free superluminal light propagation in a three level
  pump-probe system

abstract:
  We investigate the dispersion and the absorption properties of a weak probe
field in a three-level pump-probe atomic system. It is shown that the slope of
dispersion changes from positive to negative just with the intensity of the
coherent or indirect incoherent pumping fields. It is demonstrated that the
absorption free superluminal light propagation is appeared in this system.


title:
Quantum anharmonic oscillator and its statistical properties in the
  first quantization scheme

abstract:
  A family of quantum anharmonic oscillators is studied in any finite spatial
dimension in the scheme of first quantization and the investigation of their
eigenenergies is presented. The statistical properties of the calculated
eigenenergies are compared with the theoretical predictions inferred from the
Random Matrix theory. Conclusions are derived.


title:
Radford, Drinfeld, and Cardy boundary states in (1,p) logarithmic
  conformal field models

abstract:
  We introduce p-1 pseudocharacters in the space of (1,p) model vacuum torus
amplitudes to complete the distinguished basis in the 2p-dimensional fusion
algebra to a basis in the whole (3p-1)-dimensional space of torus amplitudes,
and the structure constants in this basis are integer numbers. We obtain a
generalized Verlinde-formula that gives these structure constants. In the
context of theories with boundaries, we identify the space of vacuum torus
amplitudes with the space of Ishibashi states. Then, we propose 3p-1 boundary
states satisfying the Cardy condition.


title:
How to fix a broken symmetry: Quantum dynamics of symmetry restoration
  in a ferromagnetic Bose-Einstein condensate

abstract:
  We discuss the dynamics of a quantum phase transition in a spin-1
  Bose-Einstein condensate when it is driven from the magnetized
broken-symmetry phase to the unmagnetized ``symmetric'' polar phase. We
determine where the condensate goes out of equilibrium as it approaches the
critical point, and compute the condensate magnetization at the critical point.
This is done within a quantum Kibble-Zurek scheme traditionally employed in the
context of symmetry-breaking quantum phase transitions. Then we study the
influence of the nonequilibrium dynamics near a critical point on the
condensate magnetization. In particular, when the quench stops at the critical
point, nonlinear oscillations of magnetization occur. They are characterized by
a period and an amplitude that are inversely proportional. If we keep driving
the condensate far away from the critical point through the unmagnetized
``symmetric'' polar phase, the amplitude of magnetization oscillations slowly
decreases reaching a non-zero asymptotic value. That process is described by
the equation that can be mapped onto the classical mechanical problem of a
particle moving under the influence of harmonic and ``anti-friction'' forces
whose interplay leads to surprisingly simple fixed-amplitude oscillations. We
obtain several scaling results relating the condensate magnetization to the
quench rate, and verify numerically all analytical predictions.


title: Quantum anharmonic oscillator and its statistical properties

abstract:
  In the present article a family of quantum anharmonic oscillators is studied
using Hermite's function basis (Fock's basis) in the Hilbert space. The
numerical investigation of the eigenenergies of that family is presented. The
statistical properties of the calculated eigenvalues are compared with the
theoretical predictions derived from the Random Matrix Theory. Conclusions are
inferred.


title:
On q-analogs of weight multiplicities for the Lie superalgebras gl(n,m)
  and spo(2n,M)

abstract:
  The paper is devoted to the generalization of Lusztig's q-analog of weight
multiplicities to the Lie superalgebras gl(n,m) and spo(2n,M). We define such
q-analogs K_{lambda,mu}(q) for the typical modules and for the irreducible
covariant tensor gl(n,m)-modules of highest weight lambda. For gl(n,m), the
defined polynomials have nonnegative integer coefficients if the weight mu is
dominant. For spo(2n,M), we show that the positivity property holds when mu is
dominant and sufficiently far from a specific wall of the fundamental chamber.
We also establish that the q-analog associated to an irreducible covariant
tensor gl(n,m)-module of highest weight lambda and a dominant weight mu is the
generating series of a simple statistic on the set of semistandard
hook-tableaux of shape lambda and weight mu. This statistic can be regarded as
a super analog of the charge statistic defined by Lascoux and Schutzenberger.


title:
Accelerated Imaginary-time Evolution Methods for the Computation of
  Solitary Waves

abstract:
  Two accelerated imaginary-time evolution methods are proposed for the
computation of solitary waves in arbitrary spatial dimensions. For the first
method (with traditional power normalization), the convergence conditions as
well as conditions for optimal accelerations are derived. In addition, it is
shown that for nodeless solitary waves, this method converges if and only if
the solitary wave is linearly stable. The second method is similar to the first
method except that it uses a novel amplitude normalization. The performance of
these methods is illustrated on various examples. It is found that while the
first method is competitive with the Petviashvili method, the second method
delivers much better performance than the first method and the Petviashvili
method.


title:
Quantum Bound on the Specific Entropy in Strong-Coupled Scalar Field
  Theory

abstract:
  Using the Euclidean path integral approach with functional methods, we
discuss the $(g_{0} \phi^{p})_{d}$ self-interacting scalar field theory, in the
strong-coupling regime. We assume the presence of macroscopic boundaries
confining the field in a hypercube of side $L$. We also consider that the
system is in thermal equilibrium at temperature $\beta^{-1}$. For spatially
bounded free fields, the Bekenstein bound states that the specific entropy
satisfies the inequality $\frac{S}{E} < 2 \pi R$, where $R$ stands for the
radius of the smallest sphere that circumscribes the system. Employing the
strong-coupling perturbative expansion, we obtain the renormalized mean energy
$E$ and entropy $S$ for the system up to the order $(g_{0})^{-\frac{2}{p}}$,
presenting an analytical proof that the specific entropy also satisfies in some
situations a quantum bound. Defining $\epsilon_d^{(r)}$ as the renormalized
zero-point energy for the free theory per unit length, the dimensionless
quantity $\xi=\frac{\beta}{L}$ and $h_1(d)$ and $h_2(d)$ as positive analytic
functions of $d$, for the case of high temperature, we get that the specific
entropy satisfies $\frac{S}{E} < 2\pi R \frac{h_1(d)}{h_2(d)} \xi$. When
considering the low temperature behavior of the specific entropy, we have
$\frac{S}{E} <2\pi R \frac{h_1(d)}{\epsilon_d^{(r)}}\xi^{1-d}$. Therefore the
sign of the renormalized zero-point energy can invalidate this quantum bound.
If the renormalized zero point-energy is a positive quantity, at intermediate
temperatures and in the low temperature limit, there is a quantum bound.


title: Flat Tree-level Inflationary Potentials in Light of CMB and LSS Data

abstract:
  We use cosmic microwave background and large scale structure data to test a
broad and physically well-motivated class of inflationary models: those with
flat tree-level potentials (typical in supersymmetry). The non-trivial features
of the potential arise from radiative corrections which give a simple
logarithmic dependence on the inflaton field, making the models very
predictive. We also consider a modified scenario with new physics beyond a
certain high-energy cut-off showing up as non-renormalizable operators (NRO) in
the inflaton field. We find that both kinds of models fit remarkably well CMB
and LSS data, with very few free parameters. Besides, a large part of these
models naturally predict a reasonable number of e-folds. A robust feature of
these scenarios is the smallness of tensor perturbations (r < 10^{-3}). The NRO
case can give a sizeable running of the spectral index while achieving a
sufficient number of e-folds. We use Bayesian model comparison tools to assess
the relative performance of the models. We believe that these scenarios can be
considered as a standard physical class of inflationary models, on a similar
footing with monomial potentials.


title: Central extensions of groups of sections

abstract:
  If q : P -> M is a principal K-bundle over the compact manifold M, then any
invariant symmetric V-valued bilinear form on the Lie algebra k of K defines a
Lie algebra extension of the gauge algebra by a space of bundle-valued 1-forms
modulo exact forms. In the present paper we analyze the integrability of this
extension to a Lie group extension for non-connected, possibly
infinite-dimensional Lie groups K. If K has finitely many connected components
we give a complete characterization of the integrable extensions. Our results
on gauge groups are obtained by specialization of more general results on
extensions of Lie groups of smooth sections of Lie group bundles. In this more
general context we provide sufficient conditions for integrability in terms of
data related only to the group K.


title:
Complementarity of Private and Correctable Subsystems in Quantum
  Cryptography and Error Correction

abstract:
  We make an explicit connection between fundamental notions in quantum
cryptography and quantum error correction. Error-correcting subsystems (and
subspaces) for quantum channels are the key vehicles for contending with noise
in physical implementations of quantum information-processing. Private
subsystems (and subspaces) for quantum channels play a central role in
cryptographic schemes such as quantum secret sharing and private quantum
communication. We show that a subsystem is private for a channel precisely when
it is correctable for a complementary channel. This result is shown to hold
even for approximate notions of private and correctable defined in terms of the
diamond norm for superoperators.


title: Generation of spatially broadband twin beams for quantum imaging

abstract:
  We generate spatially multimode twin beams using 4-wave mixing in a hot
atomic vapor in a phase-insensitive traveling-wave amplifier configuration. The
far-field coherence area measured at 3.5 MHz is shown to be much smaller than
the angular bandwidth of the process and bright twin images with independently
quantum-correlated sub-areas can be generated with little distortion. The
available transverse degrees of freedom form a high-dimensional Hilbert space
which we use to produce quantum-correlated twin beams with finite orbital
angular momentum.


title: Generation of polycyclic groups

abstract:
  In this note we give an alternative proof of a theorem of Linnell and
Warhurst that the number of generators d(G) of a polycyclic group G is at most
d(\hat G), where d(\hat G) is the number of generators of the profinite
completion of G. While not claiming anything new we believe that our argument
is much simpler that the original one. Moreover our result gives some
sufficient condition when d(G)=d(\hat G) which can be verified quite easily in
the case when G is virtually abelian.


title:
On the existence of infinite energy solutions for nonlinear Schrodinger
  equations

abstract:
  We derive new results about existence and uniqueness of local and global
solutions for nonlinear Schrodinger equation, including self-similar global
solutions. Our analysis is performed in the framework of Marcinkiewicz spaces.


title: Gravitational inflaton decay and the hierarchy problem

abstract:
  We study implications of the large-N species solution to the hierarchy
problem, proposed by G. Dvali, for reheating of the universe after inflation.
Dvali's proposal contains additional N~10^{32} Z_2-conserved quantum fields
beyond the Standard Model particles with mass ~1 TeV, which weaken gravity by a
factor of 1/N, and thus explain the hierarchy between the Plank scale and the
electroweak scale. We show that, in this scenario, the decay rates of inflaton
fields through gravitational decay channels are enhanced by a factor of N, and
thus they decay into N species of the quantum fields very efficiently, in the
limit that quantum gravity effects are unimportant for the gravitational decay
rate. In order not to over-reheat the universe, inflaton mass, vacuum
expectation value of inflaton, or non-minimal gravitational coupling should be
tightly fine-tuned. Our conclusion holds even when the gravitational decay is
prohibited by some symmetry of the theory; the universe may still be
over-reheated via annihilation of inflatons, if the number density of inflaton
quanta is greater than the critical value.


title: Upgrade of the Glasgow photon tagging spectrometer for Mainz MAMI-C

abstract:
  The Glasgow photon tagging spectrometer at Mainz has been upgraded so that it
can be used with the 1500 MeV electron beam now available from the Mainz
microtron MAMI-C. The changes made and the resulting properties of the
spectrometer are discussed.


title: Dilepton Radiation at the CERN Super Proton Synchrotron

abstract:
  A quantitative evaluation of dilepton sources in heavy-ion reactions is
performed taking into account both thermal and non-thermal production
mechanisms. The hadronic thermal emission rate is based on an electromagnetic
current-correlation function with a low-mass region (LMR, M \lsim 1 GeV)
dominated by vector mesons (\rho, \omega, \phi) and an intermediate-mass region
(IMR, 1 GeV \le M \le 3 GeV) characterized by (the onset of) a multi-meson
continuum. A convolution of the emission rates over a thermal fireball
expansion results in good agreement with experiment in the low-mass spectra,
confirming the predicted broadening of the \rho meson in hadronic matter in
connection with the prevalence of baryon-induced medium effects. The absolute
magnitude of the LMR excess is mostly controlled by the fireball lifetime,
which in turn leads to a consistent explanation of the dilepton excess in the
IMR in terms of thermal radiation. The analysis of experimental
transverse-momentum (q_T) spectra reveals discrepancies with thermal emission
for q_T \gsim 1 GeV in noncentral In-In collisions, which we address by
extending our calculations by: (i) a refined treatment of \rho decays at
thermal freezeout, (ii) primordially produced \rho's subject to energy-loss,
(iii) Drell-Yan annihilation, and (iv) thermal radiation from t-channel meson
exchange processes. We investigate the sensitivity of dilepton spectra to the
critical temperature and hadro-chemical freezeout of the fireball. The \rho
broadening in the LMR turns out to be robust, while in the IMR Quark-Gluon
Plasma radiation is moderate unless the critical temperature is rather low.


title: Finite size corrections in the Sherrington-Kirkpatrick model

abstract:
  We argue that when the number of spins $N$ in the SK model is finite, the
Parisi scheme can be terminated after $K$ replica-symmetry breaking steps,
where $K(N) \propto N^{1/6}$. We have checked this idea by Monte Carlo
simulations: we expect the typical number of peaks and features $R$ in the
(non-bond averaged) Parisi overlap function $P_J(q)$ to be of order $2K(N)$,
and our counting (for samples of size $N$ up to 4096 spins) gives results which
are consistent with our arguments. We can estimate the leading finite size
correction for any thermodynamic quantity by finding its $K$ dependence in the
Parisi scheme and then replacing $K$ by K(N). Our predictions of how the
Edwards-Anderson order parameter and the internal energy of the system approach
their thermodynamic limit compare well with the results of our Monte Carlo
simulations. The $N$-dependence of the sample-to-sample fluctuations of
thermodynamic quantities can also be obtained; the total internal energy should
have sample-to-sample fluctuations of order $N^{1/6}$, which is again
consistent with the results of our numerical simulations.


title: Dissociation by acceleration

abstract:
  We show that mesons, described using rotating relativistic strings in a
holographic setup, undergo dissociation when their acceleration 'a' exceeds a
value which scales with the angular momentum 'J' as a_max ~ \sqrt{T_s/J}, where
'T_s' is the string tension.


title: The Structure of E6

abstract:
  We present the subalgebra structure of sl(3,O), a particular real form of E6
chosen for its relevance to particle physics through the connection between its
associated Lie group SL(3,O) and generalized Lorentz groups. Given the
complications related to the non-associativity of the octonions O and the
restriction to working with a real form of E6, we find that the traditional
methods used to study Lie algebras must be modified for our purposes. We use an
explicit representation of the Lie group SL(3,O) to produce the multiplication
table of the corresponding algebra sl(3,O). Both the multiplication table and
the group are then utilized to find subalgebras of sl(3,O). In particular, we
identify various subalgebras of the form sl(n, F) and su(n, F) within sl(3,O)
and we also find algebras corresponding to generalized Lorentz groups. Methods
based upon automorphisms of complex Lie algebras are developed to find less
obvious subalgebras of sl(3,O). While we focus on the subalgebra structure of
our real form of E6, these methods may also be used to study the subalgebra
structure of any other real form of E6. A maximal set of simultaneously
measurable observables in physics corresponds to a maximal set of Casimir
operators in the Lie algebra. We not only identify six Casimir operators in E6,
but produce a nested sequence of subalgebras and Casimir operators in E6
containing both su(3)+su(2)+u(1) corresponding to the Standard Model and the
Lorentz group of special relativity.


title: Reminiscence on the Birth of String Theory

abstract:
  These are my personal impressions of the environment in which string theory
was born, and what the important developments affecting my work were during the
hadronic string era, 1968-1974. I discuss my motivations and concerns at the
time, particularly in my work on loop amplitudes and on closed strings.


title: Lexicon management and standard formats

abstract:
  International standards for lexicon formats are in preparation. To a certain
extent, the proposed formats converge with prior results of standardization
projects. However, their adequacy for (i) lexicon management and (ii)
lexicon-driven applications have been little debated in the past, nor are they
as a part of the present standardization effort. We examine these issues. IGM
has developed XML formats compatible with the emerging international standards,
and we report experimental results on large-coverage lexica.


title:
Matching Chiral Perturbation Theory and the Dispersive Representation of
  the Scalar Kpi Form Factor

abstract:
  We perform a matching of the two loop-chiral perturbation theory
representation of the scalar Kpi form factor to a dispersive one. Knowing the
value of F_K/F_pi and f_+(0) in the Standard Model (SM) allows to determine two
O(p^6) LECs, the slope of the scalar form factor and the deviation of the
Callan-Treiman theorem. Going beyond the SM and assuming the knowledge of the
slope of the scalar form factor from experiment, the matching allows us to
determine the ratio of F_K/F_pi, f_+(0), a certain combination of non-standard
couplings, the deviation of the Callan-Treiman theorem and the two O(p^6) LECs.


title:
Linear bound for the dyadic paraproduct on weighted Lebesgue space
  $L_2(w)$

abstract:
  The dyadic paraproduct is bounded in weighted Lebesgue spaces $L_p(w)$ if and
only if the weight $w$ belongs to the Muckenhoupt class $A_p^d$. However, the
sharp bounds on the norm of the dyadic paraproduct are not known even in the
simplest $L_2(w)$ case. In this paper we prove the linear bound on the norm of
the dyadic paraproduct in the weighted Lebesgue space $L_2(w)$ using Bellman
function techniques and extrapolate this result to the $L_p(w)$ case.


title: In memoriam Maurice Gross

abstract:
  Maurice Gross (1934-2001) was both a great linguist and a pioneer in natural
language processing. This article is written in homage to his memory


title: A resource-based Korean morphological annotation system

abstract:
  We describe a resource-based method of morphological annotation of written
Korean text. Korean is an agglutinative language. The output of our system is a
graph of morphemes annotated with accurate linguistic information. The language
resources used by the system can be easily updated, which allows us-ers to
control the evolution of the per-formances of the system. We show that
morphological annotation of Korean text can be performed directly with a
lexicon of words and without morpho-logical rules.


title: Graphes param\'etr\'es et outils de lexicalisation

abstract:
  Shifting to a lexicalized grammar reduces the number of parsing errors and
improves application results. However, such an operation affects a syntactic
parser in all its aspects. One of our research objectives is to design a
realistic model for grammar lexicalization. We carried out experiments for
which we used a grammar with a very simple content and formalism, and a very
informative syntactic lexicon, the lexicon-grammar of French elaborated by the
LADL. Lexicalization was performed by applying the parameterized-graph
approach. Our results tend to show that most information in the lexicon-grammar
can be transferred into a grammar and exploited successfully for the syntactic
parsing of sentences.


title:
VLBI observations of weak extragalactic radio sources for the alignment
  of the future GAIA frame with the ICRF

abstract:
  The space astrometry mission GAIA will construct a dense optical QSO-based
celestial reference frame. For consistency between the optical and radio
positions, it will be important to align the GAIA frame and the International
Celestial Reference Frame (ICRF) with the highest accuracy. Currently, it is
found that only 10% of the ICRF sources are suitable to establish this link,
either because they are not bright enough at optical wavelengths or because
they have significant extended radio emission which precludes reaching the
highest astrometric accuracy. In order to improve the situation, we have
initiated a VLBI survey dedicated to finding additional high-quality radio
sources for aligning the two frames. The sample consists of about 450 sources,
typically 20 times weaker than the current ICRF sources, which have been
selected by cross-correlating optical and radio catalogues. This paper presents
the observing strategy and includes preliminary results of observation of 224
of these sources with the European VLBI Network in June 2007.


title:
Emergence of clonal selection and affinity maturation in an ab initio
  microscopic model of immunity

abstract:
  Mechanisms of immunity, and of the host-pathogen interactions in general are
among the most fundamental problems of medicine, ecology, and evolution
studies. Here, we present a microscopic, protein-level, sequence-based model of
immune system, with explicitly defined interactions between host and pathogen
proteins.. Simulations of this model show that possible outcomes of the
infection (extinction of cells, survival with complete elimination of viruses,
or chronic infection with continuous coexistence of cells and viruses)
crucially depend on mutation rates of the viral and immunoglobulin proteins.
Infection is always lethal if the virus mutation rate exceeds a certain
threshold. Potent immunoglobulins are discovered in this model via clonal
selection and affinity maturation. Surviving cells acquire lasting immunity
against subsequent infection by the same virus strain. As a second line of
defense cells develop apoptosis-like behavior by reducing their lifetimes to
eliminate viruses. These results demonstrate the feasibility of microscopic
sequence-based models of immune system, where population dynamics of the
evolving B-cells is explicitly tied to the molecular properties of their
proteins.


title: Evaluation of a Grammar of French Determiners

abstract:
  Existing syntactic grammars of natural languages, even with a far from
complete coverage, are complex objects. Assessments of the quality of parts of
such grammars are useful for the validation of their construction. We evaluated
the quality of a grammar of French determiners that takes the form of a
recursive transition network. The result of the application of this local
grammar gives deeper syntactic information than chunking or information
available in treebanks. We performed the evaluation by comparison with a corpus
independently annotated with information on determiners. We obtained 86%
precision and 92% recall on text not tagged for parts of speech.


title: Hot DQ White Dwarf Stars: A New Challenge to Stellar Evolution

abstract:
  We report the discovery of a new class of hydrogen-deficient stars: white
dwarfs with an atmosphere primarily composed of carbon, with little or no trace
of hydrogen or helium. Our analysis shows that the atmospheric parameters found
for these stars do not fit satisfactorily in any of the currently known
theories of post-asymptotic giant branch (AGB) evolution, although these
objects might be the cooler counter-part of the unique and extensively studied
PG 1159 star H1504+65. These stars, together with H1504+65, might thus form a
new evolutionary post-AGB sequence.


title: A Test of the Copernican Principle

abstract:
  The blackbody nature of the cosmic microwave background (CMB) radiation
spectrum is used in a modern test of the Copernican Principle. The reionized
universe serves as a mirror to reflect CMB photons, thereby permitting a view
of ourselves and the local gravitational potential. By comparing with
measurements of the CMB spectrum, a limit is placed on the possibility that we
occupy a privileged location, residing at the center of a large void. The
Hubble diagram inferred from lines-of-sight originating at the center of the
void may be misinterpreted to indicate cosmic acceleration. Current limits on
spectral distortions are shown to exclude the largest voids which mimic cosmic
acceleration. More sensitive measurements of the CMB spectrum could prove the
existence of such a void or confirm the validity of the Copernican Principle.


title: A square lattice algebraic spin liquid with SO(5) symmetry

abstract:
  We propose a critical spin liquid ground state for S=1/2 antiferromagnets on
the square lattice. In a renormalization group analysis of the `staggered flux'
algebraic spin liquid, we examine perturbations, present in the
antiferromagnet, which break its global SU(4) symmetry to SO(5). At physical
parameter values, we find an instability towards a fixed point with SO(5)
symmetry. We discuss the possibility that this fixed point describes a
transition between the Neel and valence bond solid states, and the relationship
to the SO(5) non-linear sigma model of Tanaka and Hu.


title:
The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: A
  4 sq. deg Galactic Plane Survey in Vulpecula (l=59)

abstract:
  We present the first results from a new 250, 350, and 500 micron Galactic
Plane survey taken with the Balloon-borne Large-Aperture Submillimeter
Telescope (BLAST) in 2005. This survey's primary goal is to identify and
characterize high-mass proto-stellar objects (HMPOs). The region studied here
covers 4 sq. deg near the open cluster NGC 6823 in the constellation Vulpecula
(l=59). We find 60 compact sources (<60'' diameter) detected simultaneously in
all three bands. Their spectral energy distributions (SEDs) are constrained
through BLAST, IRAS, Spitzer MIPS, and MSX photometry, with inferred dust
temperatures spanning ~12-40K assuming a dust emissivity index beta=1.5. The
luminosity-to-mass ratio, a distance-independent quantity, spans ~0.2-130
L_\odot M_\odot^{-1}. Distances are estimated from coincident 13CO (1->0)
velocities combined with a variety of other velocity and morphological data in
the literature. In total, 49 sources are associated with a molecular cloud
complex encompassing NGC 6823 (distance ~2.3kpc), 10 objects with the Perseus
Arm (~8.5kpc) and one object is probably in the outer Galaxy (~14kpc). Near NGC
6823, the inferred luminosities and masses of BLAST sources span ~40-10^4
L_\odot, and ~15-700 M_\odot, respectively. The mass spectrum is compatible
with molecular gas masses in other high-mass star forming regions. Several
luminous sources appear to be Ultra Compact HII regions powered by early B
stars. However, many of the objects are cool, massive gravitationally-bound
clumps with no obvious internal radiation from a protostar, and hence excellent
HMPO candidates.


title: SANEPIC: A Map-Making Method for Timestream Data From Large Arrays

abstract:
  We describe a map-making method which we have developed for the Balloon-borne
Large Aperture Submillimeter Telescope (BLAST) experiment, but which should
have general application to data from other submillimeter arrays. Our method
uses a Maximum Likelihood based approach, with several approximations, which
allows images to be constructed using large amounts of data with fairly modest
computer memory and processing requirements. This new approach, Signal And
Noise Estimation Procedure Including Correlations (SANEPIC), builds upon
several previous methods, but focuses specifically on the regime where there is
a large number of detectors sampling the same map of the sky, and explicitly
allowing for the the possibility of strong correlations between the detector
timestreams. We provide real and simulated examples of how well this method
performs compared with more simplistic map-makers based on filtering. We
discuss two separate implementations of SANEPIC: a brute-force approach, in
which the inverse pixel-pixel covariance matrix is computed; and an iterative
approach, which is much more efficient for large maps. SANEPIC has been
successfully used to produce maps using data from the 2005 BLAST flight.


title: The Frontier of Reionization: Theory and Forthcoming Observations

abstract:
  The cosmic microwave background provides an image of the Universe 0.4 million
years after the big bang, when atomic hydrogen formed out of free electrons and
protons. One of the primary goals of observational cosmology is to obtain
follow-up images of the Universe during the epoch of reionization, hundreds of
millions of years later, when cosmic hydrogen was ionized once again by the UV
photons emitted from the first galaxies. To achieve this goal, new
observatories are being constructed, including low-frequency radio arrays
capable of mapping cosmic hydrogen through its redshifted 21cm emission, as
well as imagers of the first galaxies such as the James Webb Space Telescope
(JWST) and large aperture ground-based telescopes. The construction of these
observatories is being motivated by a rapidly growing body of theoretical work.
Numerical simulations of reionization are starting to achieve the dynamical
range required to resolve galactic sources across the scale of hundreds of
comoving Mpc, larger than the biggest ionized regions.


title: On Uniserial Modules in the Auslander-Reiten Quiver

abstract:
  This article begins the study of irreducible maps involving
finite-dimensional uniserial modules over finite-dimensional associative
algebras. We work on the classification of irreducible maps between two
uniserials over triangular algebras, and give estimates for the number of
middle terms of an almost split sequence with a uniserial end term.


title: The Balloon-borne Large Aperture Submillimeter Telescope: BLAST

abstract:
  The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a
sub-orbital surveying experiment designed to study the evolutionary history and
processes of star formation in local galaxies (including the Milky Way) and
galaxies at cosmological distances. The BLAST continuum camera, which consists
of 270 detectors distributed between 3 arrays, observes simultaneously in
broad-band (30%) spectral-windows at 250, 350, and 500 microns. The optical
design is based on a 2m diameter telescope, providing a diffraction-limited
resolution of 30" at 250 microns. The gondola pointing system enables raster
mapping of arbitrary geometry, with a repeatable positional accuracy of ~30";
post-flight pointing reconstruction to ~5" rms is achieved. The on-board
telescope control software permits autonomous execution of a pre-selected set
of maps, with the option of manual override. In this paper we describe the
primary characteristics and measured in-flight performance of BLAST. BLAST
performed a test-flight in 2003 and has since made two scientifically
productive long-duration balloon flights: a 100-hour flight from ESRANGE
(Kiruna), Sweden to Victoria Island, northern Canada in June 2005; and a
250-hour, circumpolar-flight from McMurdo Station, Antarctica, in December
2006.


title:
Extended Lagrangian formulation of time-reversible Born-Oppenheimer
  molecular dynamics for higher-order symplectic integration

abstract:
  A Lagrangian generalization of time-reversible Born-Oppenheimer molecular
dynamics [Niklasson et al., Phys. Rev. Lett. vol. 97, 123001 (2006)] is
proposed. The Lagrangian includes extended electronic degrees of freedom as
auxiliary dynamical variables in addition to the nuclear coordinates and
momenta. While the nuclear degrees of freedom propagate on the Born-Oppenheimer
potential energy surface, the extended auxiliary electronic degrees of freedom
evolve as a harmonic oscillator centered around the adiabatic propagation of
the self-consistent ground state. The formulation enables the application of
higher-order symplectic or geometric integration schemes that are stable and
energy conserving even under incomplete self-consistency convergence. It is
demonstrated how the extended Born-Oppenheimer molecular dynamics improves the
accuracy by over an order of magnitude compared to previous formulations at the
same level of computational cost.


title: Ensemble Averaged Conductance Fluctuations in Anderson Localized Systems

abstract:
  We demonstrate the presence of energy dependent fluctuations in the
localization length, which depend on the disorder distribution. These
fluctuations lead to Ensemble Averaged Conductance Fluctuations (EACF) and are
enhanced by large disorder. For the binary distribution the fluctuations are
strongly enhanced in comparison to the Gaussian and uniform distributions.
These results have important implications on ensemble averaged quantities, such
as the transmission through quantum wires, where fluctuations can subsist to
very high temperatures. For the non-fluctuating part of the localization length
in one dimension we obtained an improved analytical expression valid for all
disorder strengths by averaging the probability density.


title: The sphericity of the complex of non-degenerate subspaces

abstract:
  We prove that the complex of proper non-trivial non-degenerate subspaces of a
finite-dimensional vector space endowed with a non-degenerate sesquilinear form
is homotopy equivalent to a wedge of spheres. Additionally, we show that the
same is true for a slight generalization, the so-called generalized Phan
geometries of type A_n. These generalized Phan geometries occur as relative
links of certain filtrations. Their sphericity implies finiteness properties of
suitable arithmetic groups and allows for a revision of Phan's
group-theoretical local recognition of suitable finite groups of Lie type with
simply laced diagram.


title:
Spatially-resolved electronic and vibronic properties of single
  diamondoid molecules

abstract:
  Diamondoids are a unique form of carbon nanostructure best described as
hydrogen-terminated diamond molecules. Their diamond-cage structures and
tetrahedral sp3 hybrid bonding create new possibilities for tuning electronic
band gaps, optical properties, thermal transport, and mechanical strength at
the nanoscale. The recently-discovered higher diamondoids (each containing more
than three diamond cells) have thus generated much excitement in regards to
their potential versatility as nanoscale devices. Despite this excitement,
however, very little is known about the properties of isolated diamondoids on
metal surfaces, a very relevant system for molecular electronics. Here we
report the first molecular scale study of individual tetramantane diamondoids
on Au(111) using scanning tunneling microscopy and spectroscopy. We find that
both the diamondoid electronic structure and electron-vibrational coupling
exhibit unique spatial distributions characterized by pronounced line nodes
across the molecular surfaces. Ab-initio pseudopotential density functional
calculations reveal that the observed dominant electronic and vibronic
properties of diamondoids are determined by surface hydrogen terminations, a
feature having important implications for designing diamondoid-based molecular
devices.


title: Scattering-free plasmonic optics with anisotropic metamaterials

abstract:
  We develop an approach to utilize anisotropic metamaterials to solve one of
the fundamental problems of modern plasmonics -- parasitic scattering of
surface waves into free-space modes, opening the road to truly two-dimensional
plasmonic optics. We illustrate the developed formalism on examples of
plasmonic refractor and plasmonic crystal, and discuss limitations of the
developed technique and its possible applications for sensing and imaging
structures, high-performance mode couplers, optical cloaking structures, and
dynamically reconfigurable electro-plasmonic circuits.


title:
Thermodynamics of Ising spins on the Triangular Kagome Lattice: Exact
  analytical method and Monte Carlo simulations

abstract:
  We study the thermodynamics of Ising spins on the triangular kagome lattice
(TKL) using exact analytic methods as well as Monte Carlo simulations. We
present the free energy, internal energy, specific heat, entropy, sublattice
magnetizations, and susceptibility. We describe the rich phase diagram of the
model as a function of coupling constants, temperature, and applied magnetic
field. For frustrated interactions in the absence of applied field, the ground
state is a spin liquid phase with integer residual entropy per spin
$s_0/k_B={1/9} \ln 72\approx 0.4752...$. In weak applied field, the system maps
to the dimer model on a honeycomb lattice, with irrational residual entropy
0.0359 per spin and quasi-long-range order with power-law spin-spin
correlations that should be detectable by neutron scattering. The power-law
correlations become exponential at finite temperatures, but the correlation
length may still be long.


title: Search for Lepton Flavor Violating Decays of the Neutral Kaon

abstract:
  The Fermilab KTeV experiment has searched for lepton flavor violating decays
of the KL meson in three decay modes. We observe no events in the signal region
for any of the modes studied, and we set the following upper limits for their
branching ratios at the 90% CL: BR(KL--> pi0 mu e) < 7.56 x 10^(-11); BR(KL-->
pi0 pi0 mu e) < 1.64 x 10^(-10); BR(pi0 --> mu e) < 3.59 x 10^{-10).


title: Spectral inequalities for Schroedinger operators with surface potentials

abstract:
  We prove sharp Lieb-Thirring inequalities for Schroedinger operators with
potentials supported on a hyperplane and we show how these estimates are
related to Lieb-Thirring inequalities for relativistic Schroedinger operators.


title: Dynamo Action in Fully Convective Low-Mass Stars

abstract:
  Recent observations indicate that fully convective stars can effectively
build magnetic fields without the aid of a tachocline of shear, that those
fields can possess large-scale components, and that they may sense the effects
of rotation. Motivated by these puzzles, we present global three-dimensional
simulations of convection and dynamo action in the interiors of fully
convective M-dwarfs of 0.3 solar masses. We use the Anelastic Spherical
Harmonic (ASH) code, adopting a spherical computational domain that extends
from 0.08-0.96 times the overall stellar radius. We find that such fully
convective stars can generate magnetic fields of several kG strength, roughly
in equipartition with the convective flows. Differential rotation is
established in hydrodynamic progenitor calculations, but strongly quenched in
MHD simulations because of strong Maxwell stresses exerted by the magnetic
fields. Despite the absence of interior angular velocity contrasts, the
magnetic fields possess strong mean (axisymmetric) components, which we
attribute partly to the very strong influence of rotation upon the slowly
overturning flows.


title: Efficiently computing Groebner bases of ideals of points

abstract:
  We present an algorithm for computing Groebner bases of vanishing ideals of
points that is optimized for the case when the number of points in the
associated variety is less than the number of indeterminates. The algorithm
first identifies a set of essential variables, which reduces the time
complexity with respect to the number of indeterminates, and then uses PLU
decompositions to reduce the time complexity with respect to the number of
points. This gives a theoretical upper bound for its time complexity that is an
order of magnitude lower than the known one for the standard Buchberger-Moeller
algorithm if the number of indeterminates is much larger than the number of
points. Comparison of implementations of our algorithm and the standard
Buchberger-Moeller algorithm in Macaulay 2 confirm the theoretically predicted
speedup. This work is motivated by recent applications of Groebner bases to the
problem of network reconstruction in molecular biology.


title: Color Transfer Enhancement for Heavy Quarkonium Production

abstract:
  We study the transfer of color between a heavy quark pair and an unpaired
heavy quark or antiquark moving at a nonrelativistic velocity with respect to
the pair. We find that the open heavy quark or antiquark can catalyze the
transformation of the pair from octet representation at short distances to
singlet at long distances. This process is infrared sensitive in general, and
we exhibit double poles in dimensional regularization at
next-to-next-to-leading order in the transition probability. Because of their
dependence on kinematic variables, these poles cannot be matched to the
non-perturbative matrix elements of effective field theories based on a single
heavy quark pair.


title: Gaussian entanglement of symmetric two-mode Gaussian states

abstract:
  A Gaussian degree of entanglement for a symmetric two-mode Gaussian state can
be defined as its distance to the set of all separable two-mode Gaussian
states. The principal property that enables us to evaluate both Bures distance
and relative entropy between symmetric two-mode Gaussian states is the
diagonalization of their covariance matrices under the same beam-splitter
transformation. The multiplicativity property of the Uhlmann fidelity and the
additivity of the relative entropy allow one to finally deal with a single-mode
optimization problem in both cases. We find that only the Bures-distance
Gaussian entanglement is consistent with the exact entanglement of formation.


title:
Resolving Gas Dynamics in the Circumnuclear Region of a Disk Galaxy in a
  Cosmological Simulation

abstract:
  Using a hydrodynamic adaptive mesh refinement code, we simulate the growth
and evolution of a galaxy, which could potentially host a supermassive black
hole, within a cosmological volume. Reaching a dynamical range in excess of 10
million, the simulation follows the evolution of the gas structure from
super-galactic scales all the way down to the outer edge of the accretion disk.
Here, we focus on global instabilities in the self-gravitating, cold,
turbulence-supported, molecular gas disk at the center of the model galaxy,
which provide a natural mechanism for angular momentum transport down to sub-pc
scales. The gas density profile follows a power-law scaling as r^-8/3,
consistent with an analytic description of turbulence in a quasi-stationary
circumnuclear disk. We analyze the properties of the disk which contribute to
the instabilities, and investigate the significance of instability for the
galaxy's evolution and the growth of a supermassive black hole at the center.


title: Gaped graphene bilayer: disorder and magnetic field effects

abstract:
  Double layer graphene is a gapless semiconductor which develops a finite gap
when the layers are placed at different electrostatic potentials. We study,
within the tight-biding approximation, the electronic properties of the gaped
graphene bilayer in the presence of disorder, perpendicular magnetic field, and
transverse electric field. We show that the gap is rather stable in the
presence of diagonal disorder. We compute the cyclotron effective mass in the
semi-classical approximation, valid at low magnetic fields. Landau level
formation is clearly seen in zigzag and armchair ribbons of the gaped bilayer
at intermediate magnetic fields.


title: Generalized Koszul properties for augmented algebras

abstract:
  Under certain conditions, a filtration on an augmented algebra A admits a
related filtration on the Yoneda algebra E(A) := Ext_A(K, K). We show that
there exists a bigraded algebra monomorphism from gr E(A) to E_Gr(gr A), where
E_Gr(gr A) is the graded Yoneda algebra of gr A. This monomorphism can be
applied in the case where A is connected graded to determine that A has the K_2
property recently introduced by Cassidy and Shelton.


title: Geometrodynamical Distances to the Galaxy's Hydrogen Streams

abstract:
  We present a geometrodynamical method for determining distances to orbital
streams of HI gas in the Galaxy. The method makes use of our offset from the
Galactic centre and assumes that the gas comprising the stream nearly follows a
planar orbit about the Galactic centre. We apply this technique to the
Magellanic Stream and determine the distances to all points along it; a
consistency check shows that the angular momentum is approximately constant.
Applying this technique to the Large Magellanic Cloud itself gives an
independent distance which agrees within its accuracy of around 10%. Relaxing
the demand for exact conservation of energy and angular momentum at all points
along the stream allows for an increase in orbital period between the lagging
end and the front end led by the Magellanic Clouds. Similar methods are
applicable to other long streams of high-velocity clouds, provided they also
nearly follow planar orbits; these would allow otherwise unknown distances to
be determined.


title: Modeling force-induced bio-polymer unfolding

abstract:
  We study the conformations of polymer chains in a poor solvent, with and
without bending rigidity, by means of a simple statistical mechanics model.
This model can be exactly solved for chains of length up to N=55 using exact
enumeration techniques. We analyze in details the differences between the
constant force and constant distance ensembles for large but finite N. At low
temperatures, and in the constant force ensemble, the force-extension curve
shows multiple plateaus (intermediate states), in contrast with the abrupt
transition to an extended state prevailing in the $N \to \infty$ limit. In the
constant distance ensemble, the same curve provides a unified response to
pulling and compressing forces, and agrees qualitatively with recent
experimental results. We identify a cross-over length, proportional to $N$,
below which the critical force of unfolding decreases with temperature, while
above, it increases wiyh temperature. Finally, the force-extension curve for
stiff chains exhibits "saw-tooth" like behavior, as observed in protein
unfolding experiments.


title: Collapsing Manifolds with Boundary

abstract:
  This manuscript studies manifolds-with-boundary collapsing in the
Gromov-Hausdorff topology. The main aim is an understanding of the relationship
of the topology and geometry of a limiting sequence of manifolds-with-boundary
to that of a limit space, which is presumed to be without geodesic terminals.
  The main result establishes a disc bundle structure for any
manifold-with-boundary having two-sided bounds on sectional curvature and
second fundamental form, and a lower bound on intrinsic injectivity radius,
which is sufficiently close in the Gromov-Hausdorff topology to a closed
manifold.
  The second main result identifies Gromov-Hausdorff limits of certain
sequences of manifolds-with-boundary as Alexandrov spaces of curvature bounded
below.


title: Averages of elliptic curve constants

abstract:
  We compute the averages over elliptic curves of the constants occurring in
the Lang-Trotter conjecture, the Koblitz conjecture, and the cyclicity
conjecture. The results obtained confirm the consistency of these conjectures
with the corresponding ``theorems on average'' obtained recently by various
authors.


title: A spectral stability theorem for large forbidden graphs

abstract:
  We extend the classical stability theorem of Erdos and Simonovits in two
directions: first, we allow the order of the forbidden graph to grow as log of
order of the host graph, and second, our extremal condition is on the spectral
radius of the host graph.


title:
Radio galaxies in the 2SLAQ Luminous Red Galaxy survey: II. The stellar
  populations of radio-loud and radio-quiet LRGs

abstract:
  We present an analysis of the optical spectra of a volume-limited sample of
375 radio galaxies at redshift 0.4<z<0.7 from the 2dF-SDSS Luminous Red Galaxy
and QSO (2SLAQ) redshift survey. We investigate the evolution of the stellar
populations and emission-line properties of these galaxies. By constructing
composite spectra and comparing with a matched sample of radio-quiet sources
from the same survey, we also investigate the effect on the galaxy of the
presence of an active nucleus.
  The composite spectra, binned by redshift and radio luminosity, all require
two components to describe them, which we interpret as an old and a younger
population. We found no evolution with redshift of the age of the younger
population in radio galaxies, nor were they different from the radio-quiet
comparison sample. Similarly, there is no correlation with radio power, with
the exception that the most powerful radio sources (P(1.4) > 10^26 W/Hz) have
younger stars and stronger emission lines than the less powerful sources. This
suggests that we have located the threshold in radio power where strong
emission lines "switch on", at radio powers of around 10^26 W/Hz. Except for
the very powerful radio galaxies, the presence of a currently-active radio AGN
does not appear to be correlated with any change in the observed stellar
population of a luminous red galaxy at z~0.5.


title:
Manifestations of Broken Symmetry: The Surface Phases of
  Ca(2-x)Sr(x)RuO4

abstract:
  The surface structural phases of Ca(2-x)Sr(x)RuO(4) are investigated using
quantitative Low Energy Electron Diffraction. The broken symmetry at the
surface enhances the structural instability against the RuO6 rotational
distortion while diminishing the instability against the RuO6 tilt distortion
occurring within the bulk crystal. As a result, suppressed structural and
electronic surface phase transition temperatures are observed, including the
appearance of an inherent Mott metal-to-insulator transition for x = 0.1 and
possible modifications of the surface quantum critical point near xc ~ 0.5.


title: Spectral saturation: inverting the spectral Turan theorem

abstract:
  We prove that if the spectral radius of a graph G of order n is larger than
the spectral radius of the r-partite Turan graph of the same order, then G
contains various supergraphs of the complete graph of order r+1. In particular
G contains a complete r-partite graph of size log n with one edge added to the
first part. These results complete a project of Erdos from 1963. We also give
corresponding stability results.


title: A negative mass theorem for the 2-Torus

abstract:
  For a closed surface M with metric g, the Robin mass m(p) at the point p is
the value of the Green function G(p,q) at p=q after the logarithmic singularity
has been removed. The Laplacian-mass is the average value of the Robin mass,
minus the value of the Robin mass for the round sphere of the same area. The
Laplacian-mass is a spectral invariant which is a natural analog of the ADM
mass for asymptotically flat manifolds. We show that if M is a torus, then the
minimum value of the Laplacian-mass on the conformal class of g is negative. It
is attained by a (smooth) metric for which one gets a sharp logarithmic
Hardy-Littlewood-Sobolev inequality and Onofri-type inequality. If the flat
metric in the conformal class is sufficiently long and thin, then the minimizer
for the Laplacian-mass is non-flat.


title:
Generalized duality for graphs on surfaces and the signed
  Bollobas-Riordan polynomial

abstract:
  We generalize the natural duality of graphs embedded into a surface to a
duality with respect to a subset of edges. The dual graph might be embedded
into a different surface. We prove a relation between the signed
Bollobas-Riordan polynomials of dual graphs. This relation unifies various
recent results expressing the Jones polynomial of links as specializations of
the Bollobas-Riordan polynomials.


title: Analytic Central Orbits and their Transformation Group

abstract:
  A useful crude approximation for Abelian functions is developed and applied
to orbits. The bound orbits in the power-law potentials A*r^{-alpha} take the
simple form (l/r)^k = 1 + e cos(m*phi), where k = 2 - alpha > 0 and 'l' and 'e'
are generalisations of the semi-latus-rectum and the eccentricity. 'm' is given
as a function of 'eccentricity'. For nearly circular orbits 'm' is sqrt{k},
while the above orbit becomes exact at the energy of escape where 'e' is one
and 'm' is 'k'. Orbits in the logarithmic potential that gives rise to a
constant circular velocity are derived via the limit of small alpha. For such
orbits, r^2 vibrates almost harmonically whatever the 'eccentricity'. Unbound
orbits in power-law potentials are given in an appendix. The transformation of
orbits in one potential to give orbits in a different potential is used to
determine orbits in potentials that are positive powers of r. These
transformations are extended to form a group which associates orbits in sets of
six potentials, e.g. there are corresponding orbits in the potentials
proportional to r, r^{-2/3}, r^{-3}, r^{-6}, r^{4/3} and r^{-4}. A degeneracy
reduces this to three, which are r^{-1}, r^2 and r^{-4} for the Keplerian case.
A generalisation of this group includes the isochrone with the Kepler set.


title: Fourier transform inequalities for phylogenetic trees

abstract:
  Phylogenetic invariants are not the only constraints on site-pattern
frequency vectors for phylogenetic trees. A mutation matrix, by its definition,
is the exponential of a matrix with non-negative off-diagonal entries; this
positivity requirement implies non-trivial constraints on the site-pattern
frequency vectors. We call these additional constraints ``edge-parameter
inequalities.'' In this paper, we first motivate the edge-parameter
inequalities by considering a pathological site-pattern frequency vector
corresponding to a quartet tree with a negative internal edge. This
site-pattern frequency vector nevertheless satisfies all of the constraints
described up to now in the literature. We next describe two complete sets of
edge-parameter inequalities for the group-based models; these constraints are
square-free monomial inequalities in the Fourier transformed coordinates. These
inequalities, along with the phylogenetic invariants, form a complete
description of the set of site-pattern frequency vectors corresponding to
\emph{bona fide} trees. Said in mathematical language, this paper explicitly
presents two finite lists of inequalities in Fourier coordinates of the form
``monomial $\leq 1$,'' each list characterizing the phylogenetically relevant
semialgebraic subsets of the phylogenetic varieties.


title: Graphs with many copies of a given subgraph

abstract:
  We show that if a graph G of order n contains many copies of a given subgraph
H, then it contains a blow-up of H of order log n.


title:
Dynamical Zodiacal Cloud Models Constrained by High Resolution
  Spectroscopy of the Zodiacal Light (Icarus, in press)

abstract:
  The simulated Doppler shifts of the solar Mg I Fraunhofer line produced by
scattering on the solar light by asteroidal, cometary, and trans-Neptunian dust
particles are compared with the shifts obtained by Wisconsin H-Alpha Mapper
(WHAM) spectrometer. The simulated spectra are based on the results of
integrations of the orbital evolution of particles. The deviation of the
derived spectral parameters for various sources of dust used in the model
reached maximum at the elongation (measured eastward from the Sun) between 90
deg and 120 deg. For the future zodiacal light Doppler shifts measurements, it
is important to pay a particular attention to observing at this elongation
range. At the elongations of the fields observed by WHAM, the model-predicted
Doppler shifts were close to each other for several scattering functions
considered. Therefore the main conclusions of our paper don't depend on a
scattering function and mass distribution of particles if they are reasonable.
A comparison of the dependencies of the Doppler shifts on solar elongation and
the mean width of the Mg I line modeled for different sources of dust with
those obtained from the WHAM observations shows that the fraction of cometary
particles in zodiacal dust is significant and can be dominant. Cometary
particles originating inside Jupiter's orbit and particles originating beyond
Jupiter's orbit (including trans-Neptunian dust particles) can contribute to
zodiacal dust about 1/3 each, with a possible deviation from 1/3 up to 0.1-0.2.
The fraction of asteroidal dust is estimated to be about 0.3-0.5. The mean
eccentricities of zodiacal particles located at 1-2 AU from the Sun that better
fit the WHAM observations are between 0.2 and 0.5, with a more probable value
of about 0.3.


title: Globally Anisotropic High Porosity Silica Aerogels

abstract:
  We discuss two methods by which high porosity silica aerogels can be
engineered to exhibit global anisotropy. First, anisotropy can be introduced
with axial strain. In addition, intrinsic anisotropy can result during growth
and drying stages and, suitably controlled, it can be correlated with
preferential radial shrinkage in cylindrical samples. We have performed small
angle X-ray scattering (SAXS) to characterize these two types of anisotropy. We
show that global anisotropy originating from either strain or shrinkage leads
to optical birefringence and that optical cross-polarization studies are a
useful characterization of the uniformity of the imposed global anisotropy.


title:
Van der Waerden/Schrijver-Valiant like Conjectures and Stable (aka
  Hyperbolic) Homogeneous Polynomials : One Theorem for all

abstract:
  Let $p$ be a homogeneous polynomial of degree $n$ in $n$ variables,
$p(z_1,...,z_n) = p(Z)$, $Z \in C^{n}$. We call such a polynomial $p$ {\bf
H-Stable} if $p(z_1,...,z_n) \neq 0$ provided the real parts $Re(z_i) > 0, 1
\leq i \leq n$. This notion from {\it Control Theory} is closely related to the
notion of {\it Hyperbolicity} used intensively in the {\it PDE} theory.
  The main theorem in this paper states that if $p(x_1,...,x_n)$ is a
homogeneous {\bf H-Stable} polynomial of degree $n$ with nonnegative
coefficients; $deg_{p}(i)$ is the maximum degree of the variable $x_i$, $C_i =
\min(deg_{p}(i),i)$ and $$ Cap(p) = \inf_{x_i > 0, 1 \leq i \leq n}
\frac{p(x_1,...,x_n)}{x_1 ... x_n} $$ then the following inequality holds $$
\frac{\partial^n}{\partial x_1... \partial x_n} p(0,...,0) \geq Cap(p) \prod_{2
\leq i \leq n} (\frac{C_i -1}{C_i})^{C_{i}-1}. $$
  This inequality is a vast (and unifying) generalization of the Van der
Waerden conjecture on the permanents of doubly stochastic matrices as well as
the Schrijver-Valiant conjecture on the number of perfect matchings in
$k$-regular bipartite graphs. These two famous results correspond to the {\bf
H-Stable} polynomials which are products of linear forms.
  Our proof is relatively simple and ``noncomputational''; it uses just very
basic properties of complex numbers and the AM/GM inequality.


title: The energy of C4-free graphs of bounded degree

abstract:
  Answering some questions of Gutman, we show that, except for four specific
trees, every connected graph G of order n, with no cycle of order 4 and with
maximum degree at most 3, has energy greater that its order. Here, the energy
of a graph is the sum of the moduli of its eigenvalues. We give more general
theorems and state two conjectures.


title: Connections between Kac-Moody algebras and M-theory

abstract:
  We investigate some of the motivations and consequences of the conjecture
that the Kac-Moody algebra E11 is the symmetry algebra of M-theory, and we
develop methods to aid the further investigation of this idea. The definitions
required to work with abstract root systems of Lie algebras are given in review
leading up to the definition of a Kac-Moody algebra. The motivations for the
E11 conjecture are presented and the nonlinear realisation of gravity relevant
to the conjecture is described. We give a beginner's guide to producing the
algebras of E11, relevant to M-theory, and K27, relevant to the bosonic string
theory, along with their l1 representations are constructed. Reference tables
of low level roots are produced for both the adjoint and l1 representations of
these algebras. In addition a particular group element, having a generic form
for all G+++ algebras, is shown to encode all the half-BPS brane solutions of
the maximally oxidised supergravities. Special analysis is given to the role of
space-time signature in the context of this group element and subsequent to
this analysis spacelike brane solutions are derived from the same solution
generating group element. Finally the appearance of U-duality charge multiplets
from E11 is reviewed. General formulae for finding the content of arbitrary
brane charge multiplets are given and the content of the particle and string
multiplets in dimensions 4,5,6,7 and 8 is shown to be contained in the l1
representation of E11.


title:
The unusual UV continuum of quasar Ton 34 and the possibility of
  crystalline dust absorption

abstract:
  Luminous quasars are known to display a sharp steepening of the continuum
near 1100A. This spectral feature is not well fitted by current accretion disk
models, unless comptonization of the disk emission is invoked. Absorption by
carbon crystalline dust has been proposed to account for this feature. Ton 34
(z=1.928) exhibits the steepest far-UV decline (F_nu prop nu^{-5.3}) among the
183 quasar HST-FOS spectra analyzed by Telfer et al. It is an ideal object to
test the crystalline dust hypothesis as well as alternative interpretations of
the UV break. We reconstruct the UV spectral energy distribution of Ton 34 by
combining HST, IUE and Palomar spectra. The far-UV continuum shows a very deep
continuum trough, which is bounded by a steep far-UV rise. We fit the trough
assuming nanodiamond dust grains. Extinction by carbon crystalline dust
reproduces the deep absorption trough of Ton 34 reasonably well, but not the
observed steep rise in the extreme UV. We also study the possibility of an
intrinsic continuum rollover. The dust might be part of a high velocity outflow
(13000 km/s), which is observed in absorption in the lines of CIV, OVI, NV and
Ly_alpha.


title: Secure Fractal Image Coding

abstract:
  In recent work, various fractal image coding methods are reported, which
adopt the self-similarity of images to compress the size of images. However,
till now, no solutions for the security of fractal encoded images have been
provided. In this paper, a secure fractal image coding scheme is proposed and
evaluated, which encrypts some of the fractal parameters during fractal
encoding, and thus, produces the encrypted and encoded image. The encrypted
image can only be recovered by the correct key. To keep secure and efficient,
only the suitable parameters are selected and encrypted through in-vestigating
the properties of various fractal parameters, including parameter space,
parameter distribu-tion and parameter sensitivity. The encryption process does
not change the file format, keeps secure in perception, and costs little time
or computational resources. These properties make it suitable for secure image
encoding or transmission.


title: Hyperon-Quark Mixed Phase in Compact Stars

abstract:
  We investigate the properties of the hadron-quark mixed phase in compact
stars using a Brueckner-Hartree-Fock framework for hadronic matter and the MIT
bag model for quark matter. We find that the equation of state of the mixed
phase is similar to that given by the Maxwell construction. The composition of
the mixed phase, however, is very different from that of the Maxwell
construction; in particular, hyperons are completely suppressed.


title: Efficient quantum direct communication with authentication

abstract:
  Two protocols of quantum direct communication with authentication [Phys. Rev.
A 73, 042305(2006)] were recently indicated to be insecure against the
authenticator Trent's attacks [Phys. Rev. A 75, 026301(2007)]. We present two
efficient protocols by using four Pauli operations, which are secure against
inner Trent's attacks as well as outer Eve's attacks. Finally, we generalize
them to multiparty quantum direction communication.


title: Markov invariants, plethysms, and phylogenetics (the long version)

abstract:
  We explore model based techniques of phylogenetic tree inference exercising
Markov invariants. Markov invariants are group invariant polynomials and are
distinct from what is known in the literature as phylogenetic invariants,
although we establish a commonality in some special cases. We show that the
simplest Markov invariant forms the foundation of the Log-Det distance measure.
We take as our primary tool group representation theory, and show that it
provides a general framework for analysing Markov processes on trees. From this
algebraic perspective, the inherent symmetries of these processes become
apparent, and focusing on plethysms, we are able to define Markov invariants
and give existence proofs. We give an explicit technique for constructing the
invariants, valid for any number of character states and taxa. For phylogenetic
trees with three and four leaves, we demonstrate that the corresponding Markov
invariants can be fruitfully exploited in applied phylogenetic studies.


title: Non-Uniform Structure of Matter and the Equation of State

abstract:
  We investigate the non-uniform structures and the equation of state (EOS) of
nuclear matter in the context of the first-order phase transitions (FOPT) such
as liquid-gas phase transition, kaon condensation, and hadron-quark phase
transition. During FOPT the mixed phases appear, where matter exhibits
non-uniform structures called ``Pasta'' structures due to the balance of the
Coulomb repulsion and the surface tension between two phases. We treat these
effects self-consistently, properly taking into account of the Poisson equation
and the Gibbs conditions. Consequently, they make the EOS of the mixed phase
closer to that of Maxwell construction due to the Debye screening. This is a
general feature of the mixed phase consisting of many species of charged
particles.


title:
Towards a picosecond transform-limited nitrogen-vacancy based single
  photon source

abstract:
  We analyze a nitrogen-vacancy (NV^-) colour centre based single photon source
based on cavity Purcell enhancement of the zero phonon line and suppression of
other transitions. Optimal performance conditions of the cavity-centre system
are analyzed using Master equation and quantum trajectory methods. By coupling
the centre strongly to a high-finesse optical cavity [Q ~ O(10^4-10^5), V ~
lambda^3] and using sub-picosecond optical excitation the system has striking
performance, including effective lifetime of 70 ps, linewidth of 0.01 nm, near
unit single photon emission probability and small [O(10^-5)] multi-photon
probability.


title: Hyperon-Quark Mixed Phase in Dense Matter


title:
Monoenergetic proton beams accelerated by circularly polarized laser
  with thin solid foils

abstract:
  The acceleration of ions in the interaction of circular polarized laser
pulses with overdense plasmas is investigated. For circular polarization laser
pulses, the quasi-equilibrium for electrons is established due to the light
pressure and the electrostatic field built up at the interacting front of the
laser pulse. The ions located within the skin-depth of the laser pulse can be
synchronously accelerated and bunched in the charge couple processes by the
electrostatic field, and thereby monoenergetic and high intensity proton beam
can be generated. The dynamics equations for accelerated ions are deduced and
proved by particle-in-cell simulations.


title:
Explicit Ramsey graphs and Erdos distance problem over finite Euclidean
  and non-Euclidean spaces

abstract:
  We study the Erdos distance problem over finite Euclidean and non-Euclidean
spaces. Our main tools are graphs associated to finite Euclidean and
non-Euclidean spaces that are considered in Bannai-Shimabukuro-Tanaka (2004,
2007). These graphs are shown to be asymptotically Ramanujan graphs. The
advantage of using these graphs is twofold. First, we can derive new lower
bounds on the Erdos distance problems with explicit constants. Second, we can
construct many explicit tough Ramsey graphs R(3,k).


title: Pressure dependence of the oxygen isotope effect in YBa$_2$Cu$_4$O$_8$

abstract:
  We have carried out measurements of the pressure dependence to 1.2 GPa of the
oxygen isotope effect on $T_c$ in the high-$T_c$ superconductor
YBa$_2$Cu$_4$O$_8$ using a clamp cell in a SQUID magnetometer. This compound
lies close to, but just above, the 1/8$^{th}$ doping point where in
La$_{2-x}$Sr$_x$CuO$_4$ marked anomalies in isotope effects occur. Both
isotopes show the same very large pressure dependence of $T_c$ with the result
that the isotope exponent remains low ($\sim$0.08) but increases slightly with
increasing pressure. This is discussed in terms of stripe suppression, a
competing pseudogap and the effect of superconducting fluctuations.


title: Proof of the normal scalar curvature conjecture

abstract:
  In this paper, we proved the normal scalar curvature conjecture and the
Bottcher-Wenzel conjecture.


title: Effect of disorder on the ground-state properties of graphene

abstract:
  We calculate the ground-state energy of Dirac electrons in graphene in the
presence of disorder. We take randomly distributed charged impurities at a
fixed distance from the graphene sheet and surface fluctuations (ripples) as
the main scattering mechanisms. Mode-coupling approach to scattering rate and
random-phase approximation for ground-state energy incorporating the many-body
interactions and the disorder effects yields good agreement with experimental
inverse compressibility.


title:
Rankin-Cohen Brackets and van der Pol-Type Identities for the
  Ramanujan's Tau Function

abstract:
  We use Rankin-Cohen brackets for modular forms and quasimodular forms to give
a different proof of the results obtained by D. Lanphier and D. Niebur on the
van der Pol type identities for the Ramanujan's tau function. As consequences
we obtain convolution sums and congruence relations involving the divisor
functions.


title:
Galois groups of the Lie-irreducible generalized $q$-hypergeometric
  equations of order three with $q$-real parameters : an approach using a
  density theorem

abstract:
  In this paper we compute the difference Galois groups of the Lie-irreducible
regular singular generalized q-hypergeometric equations of order 3 with q-real
parameters by using a density theorem due to Sauloy. In contrast with the
differential case, we show that these groups automatically contain the special
linear group SL(3,C).


title:
The ratio and generating function of cogrowth coefficients of finitely
  generated groups

abstract:
  Let G be a group generated by $r$ elements $g_1,g_2,..., g_r.$ Among the
reduced words in $g_1,g_2,..., g_r$ of length $n$ some, say $\gamma_n,$
represent the identity element of the group $G.$ It has been shown in a
combinatorial way that the $2n$th root of $\gamma_{2n}$ has a limit, called the
cogrowth exponent with respect to generators $g_1,g_2,..., g_r.$ We show by
analytic methods that the numbers $\gamma_n$ vary regularly; i.e. the ratio
$\gamma_{2n+2}/\gamma_{2n}$ is also convergent. Moreover we derive new precise
information on the domain of holomorphy of $\gamma(z),$ the generating function
associated with the coefficients $\gamma_n.$


title:
The Magellanic impact: Collision between the outer Galactic HI disk and
  the leading arms of the Magellanic stream

abstract:
  We show that collisions between the outer Galactic HI disk and the leading
arms (LAs) of the Magellanic stream (MS) can create giant HI holes and
chimney-like structures in the disk. Based on the results of our N-body
simulations on the last 2.5 Gyr evolution of the Large and Small Magellanic
Clouds (LMC and SMC, respectively) interacting with the Galaxy, we investigate
when and where the LAs can pass through the Galactic plane after the MS
formation. We then investigate hydrodynamical interaction between LAs and the
Galactic HI disk (``the Magellanic impact'') by using our new hydrodynamical
simulations with somewhat idealized models of the LAs. We find that about 1-3%
of the initial gas mass of the SMC, which consists of the LAs, can pass through
the outer part (R=20-35 kpc) of the Galactic HI disk about 0.2 Gyr ago. We also
find that the Magellanic impact can push out some fraction (~1%) of the outer
Galactic HI disk to form 1-10 kpc-scale HI holes and chimney-like bridges
between the LAs and the disk.


title: Probing the unparticle signal in $b \to d $ penguin processes

abstract:
  We investigate the effect of unparticles in the pure $ b \to d $ penguin
processes $ B^0 \to K^0 \bar K^0$ and $B^{+,0} \to \phi \pi^{+,0} $. Since
these processes receive dominant contributions due to the {\it top} quark in
the loop, direct and mixing-induced CP asymmetry parameters in these processes
are expected to be vanishingly small in the standard model. We find that due to
the unparticle effect sizable nonzero CP violation could be possible in these
channels.


title:
One-dimensional quantum cellular automata over finite, unbounded
  configurations

abstract:
  One-dimensional quantum cellular automata (QCA) consist in a line of
identical, finite dimensional quantum systems. These evolve in discrete time
steps according to a local, shift-invariant unitary evolution. By local we mean
that no instantaneous long-range communication can occur. In order to define
these over a Hilbert space we must restrict to a base of finite, yet unbounded
configurations. We show that QCA always admit a two-layered block
representation, and hence the inverse QCA is again a QCA. This is a striking
result since the property does not hold for classical one-dimensional cellular
automata as defined over such finite configurations. As an example we discuss a
bijective cellular automata which becomes non-local as a QCA, in a rare case of
reversible computation which does not admit a straightforward quantization. We
argue that a whole class of bijective cellular automata should no longer be
considered to be reversible in a physical sense. Note that the same two-layered
block representation result applies also over infinite configurations, as was
previously shown for one-dimensional systems in the more elaborate formalism of
operators algebras [9]. Here the proof is made simpler and self-contained,
moreover we discuss a counterexample QCA in higher dimensions.


title: Exotic mesons: status and future

abstract:
  The evidence for the existence of mesons with exotic quantum numbers and of
hybrid candidates with non-exotic quantum numbers is critically reviewed,
including candidates with hidden charm. Aims and methods of future searches for
hybrid mesons are briefly discussed.


title: Quantization of exciton in magnetic field background

abstract:
  The possible mismatch between the theoretical and experimental absorption of
the edge peaks in semiconductors in a magnetic field background may arise due
to the approximation scheme used to analytically calculate the absorption
coefficient. As a possible remedy we suggest to consider nontrivial boundary
conditions on x-y plane by in-equivalently quantizing the exciton in background
magnetic field. This inequivalent quantization is based on von Neumann's method
of self-adjoint extension, which is characterized by a parameter \Sigma. We
obtain bound state solution and scattering state solution, which in general
depend upon the self-adjoint extension parameter \Sigma. The parameter \Sigma
can be used to fine tune the optical absorption coefficient K(\Sigma) to match
with the experiment.


title:
Perfect Quantum Teleportation and Superdense coding with $P_{max} = 1/2$
  states

abstract:
  We conjecture that criterion for perfect quantum teleportation is that the
Groverian entanglement of the entanglement resource is $1/\sqrt{2}$. In order
to examine the validity of our conjecture we analyze the quantum teleportation
and superdense coding with $|\Phi> = (1/\sqrt{2}) (|00q_1> + |11q_2>)$, where
$|q_1>$ and $|q_2>$ are arbitrary normalized single qubit states. It is shown
explicitly that $|\Phi>$ allows perfect two-party quantum teleportation and
superdense coding scenario. Next we compute the Groverian measures for
$|\psi>=\sqrt{1/2 - b^2}|100>+b |010>+a|001> +\sqrt{1/2-a^2}|111>$ and
$|\tilde{\psi}>=a|000>+b|010>+\sqrt{1/2 - (a^2+b^2)}|100> + (1/\sqrt{2})
|111>$, which also allow the perfect quantum teleportation. It is shown that
both states have $1/\sqrt{2}$ Groverian entanglement measure, which strongly
supports that our conjecture is valid.


title:
How adding zero to the complex relation between production and
  scattering amplitudes found by van Beveren and Rupp gives the expected real
  relation

abstract:
  If a hadronic production process is dominated by two body final state
interactions, the amplitude $A$ for the production process can be expanded as a
sum of the scattering amplitudes $T$ for the relevant two body channels. Van
Beveren and Rupp have claimed that the unitarity relation ${\rm {Im}} A= T^\dag
A$ can be satisfied if the coefficients in this expansion are complex. We
demonstrate that the coefficients have to be real if the scattering amplitudes
$T$ satisfy unitarity. Van Beveren and Rupp have merely written real
coefficients as a sum of complex numbers.


title: Hadronic atoms in QCD + QED

abstract:
  We review the theory of hadronic atoms in QCD + QED, based on a
non-relativistic effective Lagrangian framework. We first provide an
introduction to the theory, and then describe several applications:
meson-meson, meson-nucleon atoms and meson-deuteron compounds. Finally, we
compare the quantum field theory framework used here with the traditional
approach, which is based on quantum-mechanical potential scattering.


title: The effect of activity on stellar temperatures and radii

abstract:
  Recent analyses of low-mass eclipsing binary stars have unveiled a
significant disagreement between the observations and the predictions of
stellar structure models. Results show that theoretical models underestimate
the radii and overestimate the effective temperatures of low-mass stars but
yield luminosities that accord with observations. A hypothesis based upon the
effects of stellar activity was put forward to explain the discrepancies. In
this paper we study the existence of the same trend in single active stars and
provide a consistent scenario to explain systematic differences between active
and inactive stars in the H-R diagram reported earlier. The analysis is done
using single field stars of spectral types late-K and M and computing their
bolometric magnitudes and temperatures through infrared colours and spectral
indices. The properties of the stars in samples of active and inactive stars
are compared statistically to reveal systematic differences. After accounting
for a number of possible bias effects, active stars are shown to be cooler than
inactive stars of similar luminosity therefore implying a larger radius as
well, in proportions that are in excellent agreement with those found from
eclipsing binaries. The present results generalise the existence of strong
radius and temperature dependences on stellar activity to the entire population
of low-mass stars, regardless of their membership in close binary systems.


title: 3C454.3 reveals the structure and physics of its 'blazar zone'

abstract:
  Recent multi-wavelength observations of 3C454.3, in particular during its
giant outburst in 2005, put severe constraints on the location of the 'blazar
zone', its dissipative nature, and high energy radiation mechanisms. As the
optical, X-ray, and millimeter light-curves indicate, significant fraction of
the jet energy must be released in the vicinity of the millimeter-photosphere,
i.e. at distances where, due to the lateral expansion, the jet becomes
transparent at millimeter wavelengths. We conclude that this region is located
at ~10 parsecs, the distance coinciding with the location of the hot dust
region. This location is consistent with the high amplitude variations observed
on ~10 day time scale, provided the Lorentz factor of a jet is ~20. We argue
that dissipation is driven by reconfinement shock and demonstrate that X-rays
and gamma-rays are likely to be produced via inverse Compton scattering of
near/mid IR photons emitted by the hot dust. We also infer that the largest
gamma-to-synchrotron luminosity ratio ever recorded in this object - having
taken place during its lowest luminosity states - can be simply due to weaker
magnetic fields carried by a less powerful jet.


title: Towards ISS disturbance attenuation for randomly switched systems

abstract:
  We are concerned with input-to-state stability (ISS) of randomly switched
systems. We provide preliminary results dealing with sufficient conditions for
stochastic versions of ISS for randomly switched systems without control
inputs, and with the aid of universal formulae we design controllers for
ISS-disturbance attenuation when control inputs are present. Two types of
switching signals are considered: the first is characterized by a statistically
slow-switching condition, and the second by a class of semi-Markov processes.


title:
Unconditionally secure quantum key-distribution with relatively strong
  signal pulse

abstract:
  We propose an unconditionally secure quantum key distribution (QKD) protocol,
which uses a relatively strong signal pulse. While our protocol shares similar
security bases as the Bennett 1992 protocol with a strong reference pulse
(B92), our scheme uses a smaller number of detectors and it is robust against
Rayleigh scattering in an optical fibre. We derive a lower bound of secret key
generation rate of our protocol and show that our protocol can cover relatively
long distances, assuming precise phase modulations and stable interferometers.


title: Icosadeltahedral geometry of fullerenes, viruses and geodesic domes

abstract:
  I discuss the symmetry of fullerenes, viruses and geodesic domes within a
unified framework of icosadeltahedral representation of these objects. The
icosadeltahedral symmetry is explained in details by examination of all of
these structures. Using Euler's theorem on polyhedra, it is shown how to
calculate the number of vertices, edges, and faces in domes, and number of
atoms, bonds and pentagonal and hexagonal rings in fullerenes. Caspar-Klug
classification of viruses is elaborated as a specific case of icosadeltahedral
geometry.

categories: physics.pop-ph cond-mat.soft physics.bio-ph q-bio.BM


title: Galactic 511 keV line from MeV millicharged dark matter

abstract:
  We present a possible explanation of the recently observed 511 keV
$\gamma$-ray anomaly with a new ``millicharged'' fermion. The new fermion is
light (${\cal O}({\rm MeV})$) but has never been observed by any collider
experiments mainly because of its tiny electromagnetic charge $\epsilon e$. We
show that constraints from its relic density in the Universe and collider
experiments allow a parameter range such that the 511 keV cosmic $\gamma$-ray
emission from the galactic bulge may be due to positron production from this
millicharged fermion.


title:
A short note on the presence of spurious states in finite basis
  approximations

abstract:
  The genesis of spurious solutions in finite basis approximations to operators
which possess a continuum and a point spectrum is discussed and a simple
solution for identifying these solutions is suggested.


title:
Bose-Einstein condensation in a decorated lattice: an application to
  supersolid

abstract:
  The Bose-Einstein condensation of vacancies in a three-dimensional decorated
lattice is considered. The model describes possible scenario of superfluidity
of solid helium, caused by the presence of zero-point vacancies in a
dislocation network. It is shown that the temperature of Bose-Einstein
condensation decreases under increase of the length of the segments of the
network, and the law of decrease depends essentially on the properties of the
vertexes of the network. If the vertexes correspond to barriers with a small
transparency, the critical temperature is inversely as the square of the length
of the segment. On the contrary, if the vertexes correspond to traps for the
vacancies (it is energetically preferable for the vacancies to localize at the
vertexes), an exponential lowering of the temperature of transition takes
place. The highest temperature of Bose-Einstein condensation is reached in the
intermediate case of vertexes with large transparency, but in the absence of
tendency of localization in them. In the latter case the critical temperature
is inversely as the length of the segment.


title: Measurement of eta meson decays into lepton-antilepton pairs

abstract:
  A search for rare lepton decays of the eta meson was performed using the WASA
detector at CELSIUS. Two candidates for double Dalitz decay eta->e+e-e+e-
events are reported with a background of 1.3+/-0.2 events. This allows to set
an upper limit to the branching ratio of 9.7E-5 (90% CL). The branching ratio
for the decay eta->e+e-gamma is determined to (7.8+/-0.5 stat+/-0.8 syst)E-3.
An upper limit (90% CL) for the branching ratio for the eta->e+e- decay is
2.7E-5 and a limit for the sum of the eta->mu+mu-mu+mu- and eta->pi+pi-mu+mu-
decays is 3.6E-4.


title: Gluon scattering in ${\cal N}=4$ Super Yang-Mills at finite temperature

abstract:
  We extend the AdS/CFT prescription of Alday and Maldacena to finite
temperature $T$, defining the amplitude for gluon scattering in ${\cal N}=4$
Super Yang-Mills at strong coupling from string theory. It is defined by a
lightlike ''Wilson loop'' living at the horizon of the T-dual to the black hole
in AdS space. Unlike the zero temperature case, this is different from the
Wilson loop contour defined at the boundary of the AdS black hole metric, thus
at finite $T$ there is no relation between gluon scattering amplitudes and the
Wilson loop. We calculate the amplitude at strong coupling for forward
scattering of a low energy gluon ($E<T$) off a high energy gluon ($E\gg T$) in
both cut-off and generalized dimensional regularization. The generalized
dimensional regularization is defined in string theory as an IR modified
dimensional reduction. For this calculation, the corresponding usual Wilson
loop is related to the jet quenching parameter of the finite temperature ${\cal
N}=4$ SYM plasma, while the gluon scattering amplitude is related to the
viscosity coefficient.


title: Non-dense sets of subvarieties in a power of an elliptic curve

abstract:
  Let V be an algebraic variety embedded in a power of an elliptic curve, both
defined over the algebraic numbers. We show that the set of algebraic points of
V which are of bounded height and which satisfy certain algebraic conditions
are a non-dense subset of V. This result has implications in the context of the
Pink-Zilber Conjecture and Mordel-Lang plus Bogomolov Theorem.


title: Stroemgren metallicity calibration: the m1, b-y relation

abstract:
  We performed a new calibration of the Stroemgren metallicity index m1 based
on the b-y color of cluster red giant stars. The current
Metallicity-Index-Color relation is not linear in the color range 0.40 < b-y <
1.0, but provides iron abundances of cluster and field red giants with an
accuracy of ~ 0.25 dex.


title:
The Dynamical Dipole Radiation in Dissipative Collisions with Exotic
  Beams

abstract:
  Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium
nuclear interaction in regions away from saturation. In this work we present a
selection of reaction observables in dissipative collisions particularly
sensitive to the isovector part of the interaction, i.e. to the symmetry term
of the nuclear Equation of State (EoS). At low energies the behavior of the
symmetry energy around saturation influences dissipation and fragment
production mechanisms. We will first discuss the recently observed Dynamical
Dipole Radiation, due to a collective neutron-proton oscillation during the
charge equilibration in fusion and deep-inelastic collisions. We will review in
detail all the main properties, yield, spectrum, damping and angular
distributions, revealing important isospin effects. Reactions induced by
unstable 132Sn beams appear to be very promising tools to test the
sub-saturation Isovector EoS. Predictions are also presented for deep-inelastic
and fragmentation collisions induced by neutron rich projectiles. The
importance of studying violent collisions with radioactive beams at low and
Fermi energies is finally stressed.


title: Photon induced Lambda(1520) production and the role of the K^* exchange

abstract:
  We study the photon induced Lambda(1520) production in the effective
Lagrangian method near threshold, E_\gamma^{LAB}<2 GeV, and in the quark-gluon
string model at higher energies 3 GeV < E_\gamma^{LAB} < 5 GeV. In particular,
we study the role of the K^* exchange for the production of Lambda(1520) within
the SU(6) Weinberg-Tomozowa chiral unitary model proposed in Phys. Rev. D74
(2006) 034025. The coupling of the Lambda(1520) resonance to the N \bar K^*
pair, which is dynamically generated, turns out to be relatively small and,
thus, the K exchange mechanism dominates the reaction. In the higher energy
region, where experimental data are available, the quark-gluon string mechanism
with the K Regge trajectory reproduces both the energy and the angular
distribution dependences of the Lambda(1520) photo-production reaction.


title:
The intersection of a curve with a union of translated codimension 2
  subgroups in a power of an elliptic curve

abstract:
  Let C be an algebraic curve in a power of an elliptic curve, both defined
over the algebraic numbers. We show that the set of algebraic points of C which
satisfy certain conditions is a finite set. This result has implications with
the Pink-Zilber Conjeture and the Mordel-Lang plus Bogomolov Theorem for
curves.


title:
Macroscopic and Microscopic Paradigms for the Torsion Field: from the
  Test-Particle Motion to a Lorentz Gauge Theory

abstract:
  Torsion represents the most natural extension of General Relativity and it
attracted interest over the years in view of its link with fundamental
properties of particle motion. The bulk of the approaches concerning the
torsion dynamics focus their attention on their geometrical nature and they are
naturally led to formulate a non-propagating theory.
  Here we review two different paradigms to describe the role of the torsion
field, as far as a propagating feature of the resulting dynamics is concerned.
However, these two proposals deal with different pictures, i.e., a macroscopic
approach, based on the construction of suitable potentials for the torsion
field, and a microscopic approach, which relies on the identification of
torsion with the gauge field associated with the local Lorentz symmetry. We
analyze in some detail both points of view and their implications on the
coupling between torsion and matter will be investigated. In particular, in the
macroscopic case, we analyze the test-particle motion to fix the physical
trajectory, while, in the microscopic approach, a natural coupling between
torsion and the spin momentum of matter fields arises.


title: Do Elementary Particles Have an Objective Existence?

abstract:
  The formulation of quantum theory does not comply with the notion of
objective existence of elementary particles. Objective existence independent of
observation implies the distinguishability of elementary particles. In other
words: If elementary particles have an objective existence independent of
observations, then they are distinguishable. Or if elementary particles are
indistinguishable then matter cannot have existence independent of our
observation. This paper presents a simple deduction of the above statements,
their compatibility with quantum theory, an example of quantum uniqueness
situation and a suggested experiment. The conclusion is a short discussion
about the redundancy of such phenomena.


title: Young massive star clusters: globular cluster progenitors?

abstract:
  I review the long-term survival chances of young massive star clusters
(YMCs), hallmarks of intense starburst episodes often associated with violent
galaxy interactions. In particular, I address the key question as to whether at
least some of these YMCs can be considered proto-globular clusters (GCs). In
the absence of significant external perturbations, the key factor determining a
cluster's long-term survival chances is the shape of its stellar initial mass
function. I conclude that there is an increasing body of evidence that GC
formation appears to be continuing until today; their long-term evolution
crucially depends on their environmental conditions, however.


title:
Logarithmic M(2,p) Minimal Models, their Logarithmic Couplings, and
  Duality

abstract:
  A natural construction of the logarithmic extension of the M(2,p) minimal
models is presented, which generalises our previous model [0708.0802] of
percolation (p=3). Its key aspect is the replacement of the minimal model
irreducible modules by reducible ones obtained by requiring that only one of
the two principal singular vectors of each module vanish. The resulting theory
is then constructed systematically by repeatedly fusing these building block
representations. This generates indecomposable representations of the type
which signify the presence of logarithmic partner fields in the theory. The
basic data characterising these indecomposable modules, the logarithmic
couplings, are computed for many special cases and given a new structural
interpretation. Quite remarkably, a number of them are presented in closed
analytic form (for general p). These are the prime examples of
``gauge-invariant'' data - quantities independent of the ambiguities present in
defining the logarithmic partner fields. Finally, mere global conformal
invariance is shown to enforce strong constraints on the allowed spectrum: It
is not possible to include modules other than those generated by the fusion of
the model's building blocks. This generalises the statement that there cannot
exist two effective central charges in a c=0 model. It also suggests the
existence of a second ``dual'' logarithmic theory for each p. Such dual models
are briefly discussed.