title:
Associated production of graviton with $e^+e^-$ pair via photon-photon
  collisions at a linear collider

abstract:
  We investigate the process \rreeG at the future International Linear
Collider(ILC), where G_n is the Kaluza-Klein graviton in the Large Extra
Dimension Model. When the fundamental energy scale is of a few ${\rm TeV}$, the
cross section of this process can reach several hundred fb at a photon-photon
collider with $\sqrt{s}=500 \sim 1000 GeV$, and the cross section in J=2
polarized photon collision mode is much larger than that in J=0 polarized
photon collision mode. We present strategies to distinguish the graviton signal
from numerous SM backgrounds, and find that the graviton signal with extra
dimensions $\delta=3$ can be detected when ${\rm M_S} \le 2.67(1.40) {\rm TeV}$
and $\gamma \gamma$ c.m.s. energy $\sqrt{s}=1000(500) {\rm GeV}$ in unpolarized
photon collision mode, while the detecting upper limit can be increased to
2.79(1.44) ${\rm TeV}$ in $+ -$ ($\lambda_1=1$, $\lambda_2=-1$) polarized
photon collision mode(with photon polarization efficiency $P_{\gamma}=0.9$).


title:
The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and
  Stellar Dynamical Measurements

abstract:
  We present a stellar dynamical estimate of the black hole (BH) mass in the
Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as
imaging data from the ground and space, and we construct 3-integral
axisymmetric models in order to constrain the BH mass and mass-to-light ratio.
The dynamical models depend on the assumed inclination of the kinematic
symmetry axis of the stellar bulge. In the case where the bulge is assumed to
be viewed edge-on, the kinematical data give only an upper limit to the mass of
the BH of ~4e7 M_sun (1 sigma). If the bulge kinematic axis is assumed to have
the same inclination as the symmetry axis of the large-scale galaxy disk (i.e.,
23 degrees relative to the line of sight), a best-fit dynamical mass between
4-5e7 M_sun is obtained. However, because of the poor quality of the fit when
the bulge is assumed to be inclined (as determined by the noisiness of the
chi^2 surface and its minimum value), and because we lack spectroscopic data
that clearly resolves the BH sphere of influence, we consider our measurements
to be tentative estimates of the dynamical BH mass. With this preliminary
result, NGC 4151 is now among the small sample of galaxies in which the BH mass
has been constrained from two independent techniques, and the mass values we
find for both bulge inclinations are in reasonable agreement with the recent
estimate from reverberation mapping (4.57[+0.57/-0.47]e7 M_sun) published by
Bentz et al.


title: An Algebraic Chain Model of String Topology

abstract:
  A chain complex model for the free loop space of a connected, closed and
oriented manifold is presented, and on its homology, the Gerstenhaber and
Batalin-Vilkovisky algebra structures are defined and identified with the
string topology structures. The gravity algebra on the equivariant homology of
the free loop space is also modeled. The construction includes non
simply-connected case, and therefore gives an algebraic and chain level model
of Chas-Sullivan's String Topology.


title:
Magnetic Interaction in the Geometrically Frustrated Triangular Lattice
  Antiferromagnet $\rm CuFeO_2$

abstract:
  The spin wave excitations of the geometrically frustrated triangular lattice
antiferromagnet (TLA) $\rm CuFeO_2$ have been measured using high resolution
inelastic neutron scattering. Antiferromagnetic interactions up to third
nearest neighbors in the ab plane (J_1, J_2, J_3, with $J_2/J_1 \approx 0.44$
and $J_3/J_1 \approx 0.57$), as well as out-of-plane coupling (J_z, with
$J_z/J_1 \approx 0.29$) are required to describe the spin wave dispersion
relations, indicating a three dimensional character of the magnetic
interactions. Two energy dips in the spin wave dispersion occur at the
incommensurate wavevectors associated with multiferroic phase, and can be
interpreted as dynamic precursors to the magnetoelectric behavior in this
system.


title: A Thousand Invisible Cords Binding Astronomy and High-Energy Physics

abstract:
  The traditional realm of astronomy is the observation and study of the
largest objects in the Universe, while the traditional domain of high-energy
physics is the study of the smallest things in nature. But these two sciences
concerned with opposite ends of the size spectrum are, in Muir's words, bound
fast by a thousand invisible cords that cannot be broken. In this essay I
propose that collaborations of astronomers and high-energy physicists on common
problems are beneficial for both fields, and that both astronomy and
high-energy physics can advance by this close and still growing relationship.
Dark matter and dark energy are two of the binding cords I will use to
illustrate how collaborations of astronomers and high-energy physicists on
large astronomical projects can be good for astronomy, and how discoveries in
astronomy can guide high-energy physicists in their quest for understanding
nature on the smallest scales. Of course, the fields have some different
intellectual and collaborative traditions, neither of which is ideal. The
cultures of the different fields cannot be judged to be right or wrong; they
either work or they don't. When astronomers and high-energy physicists work
together, the binding cords can either encourage or choke creativity. The
challenge facing the astronomy and high-energy physics communities is to adopt
the best traditions of both fields. It is up to us to choose wisely.


title:
Time reversal Aharonov-Casher effect in mesoscopic rings with Rashba
  spin-orbital interaction

abstract:
  The time reversal Aharonov-Casher (AC) interference effect in the mesoscopic
ring structures, based on the experiment in Phys. Rev. Lett. \textbf{97},
196803 (2006), is studied theoretically. The transmission curves are calculated
from the scattering matrix formalism, and the time reversal AC interference
frequency is singled out from the Fourier spectra in numerical simulations.
This frequency is in good agreement with analytical result. It is also shown
that in the absent of magnetic field, the Altshuler-Aronov-Spivak type (time
reversal) AC interference retains under the influence of strong disorder, while
the Aharonov-Bohm type AC interference is suppressed.


title: Suzaku wide-band X-ray Spectroscopy of the Seyfert 2 AGN in NGC 4945

abstract:
  Suzaku observed a nearby Seyfert 2 galaxy NGC4945, which hosts one of the
brightest active galactic nuclei above 20 keV. Combining data from the X-ray
CCD camera (XIS) and the Hard X-ray Detector (HXD), the AGN intrinsic nuclear
emission and its reprocessed signals were observed simultaneously. The
intrinsic emission is highly obscured with an absorbing column of $\sim 5
\times 10^{24}$ cm$^{-2}$, and was detectable only above $\sim 10$ keV. The
spectrum below 10 keV is dominated by reflection continuum and emission lines
from neutral/ionized material. Along with a neutral iron K$\alpha$ line, a
neutral iron K$\beta$ and a neutral nickel K$\alpha$ line were detected for the
first time from this source. The neutral lines and the cold reflection
continuum are consistent with both originating in the same location. The
Compton down-scattered shoulder in the neutral Fe-K$\alpha$ line is $\sim 10%$
in flux of the narrow core, which confirms that the line originates from
reflection rather than transmission. The weakness of the Compton shoulder also
indicates that the reflector is probably seen nearly edge-on. Flux of the
intrinsic emission varied by a factor of $\sim 2$ within $\sim 20$ ks, which
requires the obscuring material to be geometrically thin. Broadband spectral
modeling showed that the solid angle of the neutral reflector is less than a
few $\times 10^{-2} \times 2\pi$. All this evidence regarding the reprocessed
signals suggests that a disk-like absorber/reflector is viewed from a near
edge-on angle.


title:
The symplectic structure of curves in three dimensional spaces of
  constant curvature and the equations of mathematical physics

abstract:
  This paper defines a symplectic form on the infinite dimensional Fr\'echet
manifold of framed curves of fixed length over a simply connected Riemannian
manifold of constant curvature. The paper then considers Hamiltonian systems
generated by the geometric invariants of the curves on the base manifold and
relates them to the equations of mathematical physics.


title: Exciton Effects in Optical Absorption of Boron-Nitride Nanotubes

abstract:
  Exciton effects are studied in single-wall boron-nitride (BN) nanotubes.
Linear absorption spectra are calculated with changing the chiral index of the
zigzag nanotubes. We consider the extended Hubbard model with atomic energies
at the boron and nitrogen sites. Exciton effects are calculated using the
configuration interaction technique. The Coulomb interaction dependence of the
band gap, the lowest exciton energy, and the binding energy of the exciton are
discussed. The optical gap of the (5,0) nanotube is about 6 eV at the onsite
interaction U=2t with the hopping integral t=1.2 eV. The binding energy of the
exciton is 0.50 eV for these parameters. This energy agrees well with that of
other theoretical investigations. We find that the energy gap and the binding
energy are almost independent of the geometries of the nanotubes. This novel
property is in contrast with that of the carbon nanotubes which show metallic
and semiconducting properties depending on the chiral index.


title: An Isochrone Database and a Rapid Model for Stellar Population Synthesis

abstract:
  We first presented an isochrone database that can be widely used for stellar
population synthesis studies and colour-magnitude diagram (CMD) fitting. The
database consists of the isochrones of both single star and binary star simple
stellar populations (ss-SSPs and bs-SSPs). The ranges for the age and
metallicity of populations are 0--15 Gyr and 0.0001--0.03, respectively. All
data are available for populations with Salpeter IMF and Chabrier IMF. Then
based on the isochrone database, we built a rapid stellar population synthesis
(RPS) model and calculated the high-resolution (0.3 AA) integrated spectral
energy distributions (SEDs), Lick indices and colour indices for bs-SSPs and
ss-SSPs. In particular, we calculated the UBVRIJHKLM colours, ugriz colours and
some composite colours that consist of magnitudes on different systems. As an
example for applying the isochrone database for CMD fitting, we fitted the CMDs
of star clusters M67 and NGC1868 and obtained their distance moduli, colour
excesses, stellar metallicities and ages. The results showed that the
isochrones of bs-SSPs are closer to those of real star clusters. The isochrone
database, colours, Lick indices of populations can be downloaded via
http://www.ynao.ac.cn/~bps/zhongmu/download.htm


title:
Simulation of Particle Size Effect on Dynamic Properties and Fracture of
  PTFE-W-Al Composites

abstract:
  Recent investigations of the dynamic compressive strength of cold
isostatically pressed composites of polytetrafluoroethylene (PTFE), tungsten
(W) and aluminum (Al) powders show significant differences depending on the
size of metallic particles. The addition of W increases the density and overall
strength of the sample. To investigate relatively large deformations
multi-material Eulerian and arbitrary Lagrangian-Eulerian methods, which have
the ability to efficiently handle the formation of free surfaces, were used.
The calculations indicate that the increased strength of the sample with fine
metallic particles is due to the formation of force chains under dynamic
loading. This phenomenon occurs even at larger porosity of the PTFE matrix in
comparison with samples with larger particle size of W and higher density of
the PTFE matrix.


title: Constraining supersymmetry from the satellite experiments

abstract:
  In this paper we study the detectability of $\gamma$-rays from dark matter
annihilation in the subhalos of the Milky Way by the satellite-based
experiments, EGRET and GLAST. We work in the frame of supersymmetric extension
of the standard model and assume the lightest neutralino being the dark matter
particles. Based on the N-body simulation of the evolution of dark matter
subhalos we first calculate the average intensity distribution of this new
class of $\gamma$-ray sources by neutralino annihilation. It is possible to
detect these $\gamma$-ray sources by EGRET and GLAST. Conversely, if these
sources are not detected the nature of the dark matter particls will be
constrained by these experiments, which, however, depending on the
uncertainties of the subhalo profile.


title: Entanglement Entropy in the Calogero-Sutherland Model

abstract:
  We investigate the entanglement entropy between two subsets of particles in
the ground state of the Calogero-Sutherland model. By using the duality
relations of the Jack symmetric polynomials, we obtain exact expressions for
both the reduced density matrix and the entanglement entropy in the limit of an
infinite number of particles traced out. From these results, we obtain an upper
bound value of the entanglement entropy. This upper bound has a clear
interpretation in terms of fractional exclusion statistics.

categories: cond-mat.stat-mech cond-mat.mes-hall cond-mat.str-el hep-th quant-ph


title: Topologies and Measurable Structures on the Projective Hilbert Space

abstract:
  A systematic review of the various topologies that can be defined on the
projective Hilbert space P(H), i.e., on the set of the pure quantum states, is
presented. It is shown that P(H) carries a natural topology as well as a
natural measurable structure.


title:
Structure of the Nondiffracting (Localized) Waves, and some interesting
  applications

abstract:
  Since the early works[1-4] on the so-called nondiffracting waves (called also
Localized Waves), a great deal of results has been published on this important
subject, from both the theoretical and the experimental point of view.
Initially, the theory was developed taking into account only free space;
however, in recent years, it has been extended for more complex media
exhibiting effects such as dispersion[5-7], nonlinearity[8], anisotropy[9] and
losses[10]. Such extensions have been carried out along with the development of
efficient methods for obtaining nondiffracting beams and pulses in the
subluminal, luminal and superluminal regimes[11-18]. This paper (partly a
review) addresses some theoretical methods related to nondiffracting solutions
of the linear wave equation in unbounded homogeneous media, as well as to some
interesting applications of such waves. In section II we analyze the general
structure of the Localized Waves, develop the so called Generalized
Bidirectional Decomposition, and use it to obtain several luminal and
superluminal (especially X-shaped) nondiffracting solutions of the wave
equation. In section III we develop a space-time focusing method by a
continuous superposition of X-Shaped pulses of different velocities. Section IV
addresses the properties of chirped optical X-Shaped pulses propagating in
material media without boundaries. Finally, in Section V, we show how a
suitable superposition of Bessel beams can be used to obtain stationary
localized wave fields, with a static envelope and a high transverse
localization, and whose longitudinal intensity pattern can assume any desired
shape within a chosen interval of the propagation axis.


title: Projectively Osserman manifolds

abstract:
  One says that a smooth manifold M is a pseudo-Riemannian manifold of
signature (p,q) if the tangent bundle TM is equipped with a smooth
non-degenerate symmetric inner product g of signature (p,q). Similarly one says
that M is an affine manifold if TM is equipped with a torsion free connection.
One says g is Osserman if the eigenvalues of the Jacobi operator are constant
on the pseudo-sphere bundles of unit timelike and spacelike vectors. We extend
this concept from the pseudo-Riemannian to the affine setting to define the
notion of a projectively Osserman manifold. This notion is the focus of the
paper. We establish some basic results concerning projectively Osserman
manifolds and exhibit examples of this structure which arise in several
different geometrical contexts.


title:
A Deterministic Sub-linear Time Sparse Fourier Algorithm via
  Non-adaptive Compressed Sensing Methods

abstract:
  We study the problem of estimating the best B term Fourier representation for
a given frequency-sparse signal (i.e., vector) $\textbf{A}$ of length $N \gg
B$. More explicitly, we investigate how to deterministically identify B of the
largest magnitude frequencies of $\hat{\textbf{A}}$, and estimate their
coefficients, in polynomial$(B,\log N)$ time. Randomized sub-linear time
algorithms which have a small (controllable) probability of failure for each
processed signal exist for solving this problem. However, for failure
intolerant applications such as those involving mission-critical hardware
designed to process many signals over a long lifetime, deterministic algorithms
with no probability of failure are highly desirable. In this paper we build on
the deterministic Compressed Sensing results of Cormode and Muthukrishnan (CM)
\cite{CMDetCS3,CMDetCS1,CMDetCS2} in order to develop the first known
deterministic sub-linear time sparse Fourier Transform algorithm suitable for
failure intolerant applications. Furthermore, in the process of developing our
new Fourier algorithm, we present a simplified deterministic Compressed Sensing
algorithm which improves on CM's algebraic compressibility results while
simultaneously maintaining their results concerning exponential decay.


title: On a Phase Separation Point for One - Dimensional Models

abstract:
  In the paper a one-dimensional model with nearest - neighbor interactions
$I_n, n\in \Z$ and spin values $\pm 1$ is considered. It is known that under
some conditions on parameters $I_n$ the phase transition occurs for the model.
We define a notion of "phase separation" point between two phases. We prove
that the expectation value of the point is zero and its the mean square
fluctuation is bounded by a constant $C(\beta)$ which tends to 1/4 if
$\beta\to\infty$. Here $\beta=\frac{1}{T}$, $ T>0$-temperature.


title: Will Zigzag Graphene Nanoribbon Turn to Half Metal under Electric Field?

abstract:
  At B3LYP level of theory, we predict that the half-metallicity in zigzag edge
graphene nanoribbon (ZGNR) can be realized when an external electric field is
applied across the ribbon. The critical electric field to induce the
half-metallicity decreases with the increase of the ribbon width. Both the spin
polarization and half-metallicity are removed when the edge state electrons
fully transferred from one side to the other under very strong electric field.
The electric field range under which ZGNR remain half-metallic increases with
the ribbon width. Our study demonstrates a rich field-induced spin polarization
behavior, which may leads to some important applications in spinstronics.


title: Age constraints on the Agegraphic Dark Energy Model

abstract:
  We investigate the age constraint on the agegraphic dark energy model by
using two old galaxies (LBDS 53W091 and LBDS 53W069) and the old high redshift
quasar APM 08279+5255. We find that the agegraphic dark energy model can easily
accommodate LBDS 53W091 and LBDS 53W069. To accommodate APM 08279+5255, one can
take the reduced Hubble parameter as large as h=0.64, when the fraction matter
energy density $\Omega_{m0}\approx 0.22$.


title: Near-Field Microlensing from Wide-Field Surveys

abstract:
  We estimate the rate of near-field microlensing events expected from all-sky
surveys and investigate the properties of these events. Under the assumption
that all lenses are composed of stars, our estimation of the event rate ranges
from \Gamma_{tot}~0.2 yr^{-1}$ for a survey with a magnitude limit of
V_{lim}=12 to \Gamma_{tot}~20 yr^{-1} for a survey with V_{lim}=18. We find
that the average distances to source stars and lenses vary considerably
depending on the magnitude limit, while the dependencies of the average event
time scale and lens-source transverse speed are weak and nearly negligible,
respectively. We also find that the the average lens-source proper motion of
events expected even from a survey with V_{lim}=18 would be <\mu> >~ 40 mas
yr^{-1}, implying that the source and lens of a significant fraction of
near-field events could be resolved from high-resolution follow-up
observations. From the investigation of the variation of the event
characteristics depending on the position of the sky, we find that the average
distances to source stars and lenses become shorter, the lens-source transverse
speed increases, and the time scale becomes shorter as the the galactic
latitude of the field increases. Due to the concentration of events near the
galactic plane, we find that >~ 50 % of events would be detected in the field
with b <= 20^\circ.


title:
GMRT Observations of the 2006 outburst of the Nova RS Ophiuchi: First
  detection of emission at radio frequencies < 1.4 GHz

abstract:
  The first low radio frequency (<1.4 GHz) detection of the outburst of the
recurrent nova RS Ophiuchi is presented in this letter. Radio emission was
detected at 0.61 GHz on day 20 with a flux density of ~48 mJy and at 0.325 GHz
on day 38 with a flux density of ~ 44 mJy. This is in contrast with the 1985
outburst when it was not detected at 0.327 GHz even on day 66. The emission at
low radio frequencies is clearly non-thermal and is well-explained by a
synchrotron spectrum of index alpha ~ -0.8 (S propto nu^alpha) suffering
foreground absorption due to the pre-existing, ionized, warm, clumpy red giant
wind. The absence of low frequency radio emission in 1985 and the earlier
turn-on of the radio flux in the current outburst are interpreted as being due
to higher foreground absorption in 1985 compared to that in 2006, suggesting
that the overlying wind densities in 2006 are only ~30% of those in 1985.


title:
Derivation of the Recursion Relation for the Feynman Diagrams of the CJT
  effective action

abstract:
  We derive a new recursion relation to obtain the Feynman diagrams of the
Cornwall-Jackiw-Toumboulis(CJT) effective action by using the functional
derivative identities. By using this recursion relation we show the
two-particle-irreducibility of the Feynman diagrams of the CJT effective action
by induction. We apply the recursion relation to obtain the Feynman diagrams of
the CJT effective action up to the four-loop order in case of the bosonic field
theory.


title: The evolutionary status of the semiregular variable QYSge

abstract:
  Repeated spectroscopic observations made with the 6m telescope of yielded new
data on the radial-velocity variability of the anomalous yellow supergiant
QYSge. The strongest and most peculiar feature in its spectrum is the complex
profile of NaI D lines, which contains a narrow and a very wide emission
components. The wide emission component can be seen to extend from -170 to +120
km/s, and at its central part it is cut by an absorption feature, which, in
turn, is split into two subcomponents by a narrow (16km/s at r=2.5) emission
peak. An analysis of all the Vr values leads us to adopt for the star a
systemic velocity of Vr=-21.1 km/s, which corresponds to the position of the
narrow emission component of NaI. The locations of emission-line features of
NaI D lines are invariable, which point to their formation in regions that are
external to the supergiant's photosphere. Differential line shifts of about
10km/s are revealed. The absorption lines in the spectrum of QYSge have a
substantial width of FWHM~45 km/s. The method of model atmospheres is used to
determine the following parameters: Teff=6250K, lg g=2.0, and microturbulence
Vt=4.5km/s. The metallicity of the star is found to be somewhat higher than the
solar one with an average overabundance of iron-peak elements of [Met/H]=+0.20.
The star is found to be slightly overabundant in carbon and nitrogen,
[C/Fe]=+0.25, [N/Fe]=+0.27. The alpha-process elements Mg, Si, and Ca are
slightly overabundant [alpha/H]=+0.12. The strong sodium excess, [Na/Fe]=+0.75,
is likely to be due to the dredge-up of the matter processed in the NeNa cycle.
Heavy elements of the s-process are underabundant relative to the Sun. On the
whole, the observed properties of QYSge do not give grounds for including this
star into the group of RCrB or RVTau-type type objects.


title:
Monte Carlo Studies of the Fundamental Limits of the Intrinsic
  Hyperpolarizability

abstract:
  The off-resonant hyperpolarizability is calculated using the dipole-free
sum-over-stats expression from a randomly chosen set of energies and transition
dipole moments that are forced to be consistent with the sum rules. The process
is repeated so that the distribution of hyperpolarizabilities can be
determined. We find this distribution to be a cycloid-like function. In
contrast to variational techniques that when applied to the potential energy
function yield an intrinsic hyperpolarizability less than 0.71, our Monte Carlo
method yields values that approach unity. While many transition dipole moments
are large when the calculated hyperpolarizability is near the fundamental
limit, only two excited states dominate the hyperpolarizability - consistent
with the three-level ansatz.


title: UV/IR Mixing and Black Hole Thermodynamics

abstract:
  The goal of this paper is to investigate the final stage of black hole
evaporation process in the framework of Lorentz violating Modified Dispersion
Relations(MDRs). As a consequence of MDRs, the high energy sector of the
underlying field theory does not decouple from the low energy sector, the
phenomenon which is known as UV/IR mixing. In the absence of exact
supersymmetry, we derive a modified dispersion relation which shows UV/IR
mixing by a novel energy dependence. Then we investigate the effects of these
type of MDRs on the thermodynamics of a radiating noncommutative Schwarzschild
black hole. The final stage of black hole evaporation obtained in this
framework is compared with existing pictures.


title: Finite automata for caching in matrix product algorithms

abstract:
  A diagram is introduced for visualizing matrix product states which makes
transparent a connection between matrix product factorizations of states and
operators, and complex weighted finite state automata. It is then shown how one
can proceed in the opposite direction: writing an automaton that ``generates''
an operator gives one an immediate matrix product factorization of it. Matrix
product factorizations have the advantage of reducing the cost of computing
expectation values by facilitating caching of intermediate calculations. Thus
our connection to complex weighted finite state automata yields insight into
what allows for efficient caching in matrix product algorithms. Finally, these
techniques are generalized to the case of multiple dimensions.


title:
Shapiro steps in Josephson junctions with alternating critical current
  density

abstract:
  We treat theoretically Shapiro steps in tunnel Josephson junctions with
spatially alternating critical current density. Explicit analytical formulas
for the width of the first integer (normal) and half-integer (anomalous)
Shapiro steps are derived for short junctions. We develop coarse-graining
approach, which describes Shapiro steps in the voltage-current curves of the
asymmetric grain boundaries in YBCO thin films and different
superconductor-ferromagnet-superconductor Josephson-type heterostructures.


title:
Temperature Coefficients of the Raman Peaks for the Single-Layer and
  Bi-Layer Graphene

abstract:
  We carried out micro-Raman spectroscopy of graphene layers over the
temperature range from approximately 80 K to 370 K. The number of layers was
independently confirmed by the quantum Hall measurements and atomic force
microscopy. The measured values of the temperature coefficients for the G and
2D-band frequencies of the single-layer graphene are -0.016 1/(cm K) and -0.034
1/(cm K), respectively. The G peak temperature coefficient of the bi-layer
graphene and bulk graphite are -0.015 1/(cm K) and -0.011 1/(cm K),
respectively.


title:
Dirichlet L-series with real and complex characters and their
  application to solving double sums

abstract:
  A description of the properties of \L with complex characters is given. By
using these, together with the more familiar \L with real characters, it is
shown how certain two dimensional lattice sums, which previously could not be
put into closed form, may now be expressed in this way.


title: Single production of heavy top quark from the three-site Higgsless model

abstract:
  We consider single production of the heavy top quark T predicted by the
three-site Higgsless model in future high energy collider experiments, such as
the high energy linear e^{+}e^{-} collider (ILC), the linear-ring type $ep$
collider (THERA), and the CERN Large Hadron Collider (LHC). Our numerical
results show that the possible signals of the heavy top quark T might be
observed via the process $e^{+}e^{-}\to t\bar{T}\to t\bar{t}Z$ in future ILC
experiments and via the subprocess $qb\to q'T$ at the LHC.


title:
Non-supersymmetric Attractors in Born-Infeld Black Holes with a
  Cosmological Constant

abstract:
  We investigate the attractor mechanism for spherically symmetric extremal
black holes in Einstein-Born-Infeld-dilaton theory of gravity in
four-dimensions, in the presence of a cosmological constant. We look for
solutions analytic near the horizon by using perturbation method. It is shown
that the values of the scalar fields at the horizon are only dependent on the
charges carried by the black hole and are irrelevant in their asymptotic
values. This analysis supports the validity of non-supersymmetric attractors in
the presence of higher derivative interactions in the gauge fields part and in
non-asymptotically flat spacetime.


title: H-alpha Survey of the Local Volume: Isolated Southern Galaxies

abstract:
  We present our H-alpha observations of 11 isolated southern galaxies: SDIG,
PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152,
UGCA 438, and E149-003, with distances from 1 to 7 Mpc. We have determined the
total H-alpha fluxes from these galaxies. The star formation rates in these
galaxies range from 10^{-1} (IC 4662) to 10^{-4}_{\odot}/yr (SDIG) and the gas
depletion time at the observed star formation rates lies within the range from
1/6 to 24 Hubble times H_0^{-1} .


title: On the collisions of singular points of complex algebraic plane curves

abstract:
  We study the "generic" degenerations of curves with two singular points when
the points merge. First, the notion of generic degeneration is defined
precisely. Then a method to classify the possible results of generic
degenerations is proposed in the case of linear singularity types.
  We discuss possible bounds on the singularity invariants of the resulting
type in terms of the initial types. In particular the strict upper bound on the
resulting multiplicity is proved and a sufficient condition for $\delta=const$
collision is given.


title: On the enumeration of complex plane curves with two singular points

abstract:
  We study equi-singular strata of plane curves with two singular points of
prescribed types. The method of the previous work [Kerner06] is generalized to
this case. In particular we consider the enumerative problem for plane curves
with two singular points of linear singularity types. First the problem for two
ordinary multiple points of fixed multiplicities is solved. Then the
enumeration for arbitrary linear types is reduced to the case of ordinary
multiple points and to the understanding of "merging" of singular points. Many
examples and numerical answers are given.


title:
Antiferromagnetic fluctuations in the superconducting phase of low- and
  high-temperature superconductors

abstract:
  Based on recent experimental results for electron-doped cuprate oxides and
ferromagnetic superconductors, it is shown that antiferromagnetic fluctuations
always develop in the superconducting phase of both low- and high-temperature
superconductors. The relation between the magnitude of the antiferromagnetic
pseudogap and the characteristic temperature of the antiferromagnetic pseudogap
opening is obtained. The characteristic temperature of the antiferromagnetic
pseudogap opening for metal superconductors is estimated.


title:
Preliminary study of the anti-K N interaction in a chiral constituent
  quark model

abstract:
  A preliminary investigation of the anti-K N interaction is performed within a
chiral constituent quark model by solving the resonating group method (RGM)
equation. The model parameters are taken from our previous work, which gave a
satisfactory description of the S-, P-, D-, F-wave KN scattering phase shifts.
The channel-coupling between anti-K N, pi Lambda and pi Sigma is considered,
and the scattering phase shifts as well as the bound-state problem of anti-K N
are dynamically studied. The results show that the S-wave anti-K N interaction
in the isospin I=0 channel is attractive, and in the extended chiral SU(3)
quark model such an attraction can make for an anti-K N bound state, which
appears as a pi Sigma resonance in the coupled-channel calculation, while the
chiral SU(3) quark model cannot accommodate the existence of an anti-K N bound
state. It seems that the vector meson exchanges are necessary to be introduced
in the quark-quark interactions if one tries to explain the Lambda(1405) as an
anti-K N bound state or a pi Sigma - anti-K N resonance state.


title:
Random permutations and unique fully supported ergodicity for the Euler
  adic transformation

abstract:
  There is only one fully supported ergodic invariant probability measure for
the adic transformation on the space of infinite paths in the graph that
underlies the Eulerian numbers. This result may partially justify a frequent
assumption about the equidistribution of random permutations.


title:
Particle creation, classicality and related issues in quantum field
  theory: I. Formalism and toy models

abstract:
  The quantum theory of a harmonic oscillator with a time dependent frequency
arises in several important physical problems, especially in the study of
quantum field theory in an external background. While the mathematics of this
system is straightforward, several conceptual issues arise in such a study. We
present a general formalism to address some of the conceptual issues like the
emergence of classicality, definition of particle content, back reaction etc.
In particular, we parametrize the wave function in terms of a complex number
(which we call excitation parameter) and express all physically relevant
quantities in terms it. Many of the notions -- like those of particle number
density, effective Lagrangian etc., which are usually defined using asymptotic
in-out states -- are generalized as time-dependent concepts and we show that
these generalized definitions lead to useful and reasonable results. Having
developed the general formalism we apply it to several examples. Exact analytic
expressions are found for a particular toy model and approximate analytic
solutions are obtained in the extreme cases of adiabatic and highly
non-adiabatic evolution. We then work out the exact results numerically for a
variety of models and compare them with the analytic results and
approximations. The formalism is useful in addressing the question of emergence
of classicality of the quantum state, its relation to particle production and
to clarify several conceptual issues related to this. In Paper II
(arXiv:0708.1237), which is a sequel to this, the formalism will be applied to
analyze the corresponding issues in the context of quantum field theory in
background cosmological models and electric fields.


title: Localized Backreacted Flavor Branes in Holographic QCD

abstract:
  We investigate the perturbative (in $g_s N_{D8}$) backreaction of localized
D8 branes in D4-D8 systems including in particular the Sakai Sugimoto model. We
write down the explicit expressions of the backreacted metric, dilaton and RR
form. We find that the backreaction remains small up to a radial value of $u
\ll \ell_s/(g_s N_{D8})$, and that the background functions are smooth except
at the D8 sources. In this perturbative window, the original embedding remains
a solution to the equations of motion. Furthermore, the fluctuations around the
original embedding, describing scalar mesons, do not become tachyonic due to
the backreaction in the perturbative regime. This is is due to a cancelation
between the DBI and CS parts of the D8 brane action in the perturbed
background.


title: Dispersive representation and shape of K_{l3} form factors

abstract:
  The Callan-Treiman low-energy theorem offers an opportunity to test
electroweak couplings of light quarks to the gauge boson W. To that aim, we
introduce a model-independent and accurate dispersive parametrization of the
two K_{l3} form factors. We then discuss three applications to the analysis of
K_{e3} and K_{mu3} measurements: the prediction of the ratios
Gamma(K_{mu3})/Gamma(K_{e3}), the extraction of |f_+(0)V_{us}| and finally the
possible measurement of m_u - m_d induced isospin breaking asymmetry.


title: Flipped spinfoam vertex and loop gravity

abstract:
  We introduce a vertex amplitude for 4d loop quantum gravity. We derive it
from a conventional quantization of a Regge discretization of euclidean general
relativity. This yields a spinfoam sum that corrects some difficulties of the
Barrett-Crane theory. The second class simplicity constraints are imposed
weakly, and not strongly as in Barrett-Crane theory. Thanks to a flip in the
quantum algebra, the boundary states turn out to match those of SO(3) loop
quantum gravity -- the two can be identified as eigenstates of the same
physical quantities -- providing a solution to the problem of connecting the
covariant SO(4) spinfoam formalism with the canonical SO(3) spin-network one.
The vertex amplitude is SO(3) and SO(4)-covariant. It rectifies the triviality
of the intertwiner dependence of the Barrett-Crane vertex, which is responsible
for its failure to yield the correct propagator tensorial structure. The
construction provides also an independent derivation of the kinematics of loop
quantum gravity and of the result that geometry is quantized.


title:
Particle creation, classicality and related issues in quantum field
  theory: II. Examples from field theory

abstract:
  We adopt the general formalism, which was developed in Paper I
(arXiv:0708.1233) to analyze the evolution of a quantized time-dependent
oscillator, to address several questions in the context of quantum field theory
in time dependent external backgrounds. In particular, we study the question of
emergence of classicality in terms of the phase space evolution and its
relation to particle production, and clarify some conceptual issues. We
consider a quantized scalar field evolving in a constant electric field and in
FRW spacetimes which illustrate the two extreme cases of late time adiabatic
and highly non-adiabatic evolution. Using the time-dependent generalizations of
various quantities like particle number density, effective Lagrangian etc.
introduced in Paper I, we contrast the evolution in these two limits bringing
out key differences between the Schwinger effect and evolution in the de Sitter
background. Further, our examples suggest that the notion of classicality is
multifaceted and any one single criterion may not have universal applicability.
For example, the peaking of the phase space Wigner distribution on the
classical trajectory \emph{alone} does not imply transition to classical
behavior. An analysis of the behavior of the \emph{classicality parameter},
which was introduced in Paper I, leads to the conclusion that strong particle
production is necessary for the quantum state to become highly correlated in
phase space at late times.


title:
Three-dimensional Curve Motions Induced by the Modified Korteweg-de
  Vries Equation

abstract:
  We have constructed one-phase quasi-periodic solutions of the curve equation
induced by the mKdV equation. The solution is expressed in terms of the
elliptic functions of Weierstrass. This solution can describe curve dynamics
such as a vortex filament with axial velocity embedded in an incompressible
inviscid fluid. There exist two types of curves (type-A, type-B) according to
the form of the main spectra of the finite-band integrated solution. Our
solution includes various filament shapes such as the Kelvin-type wave, the
rigid vortex, plane curves, closed curves, and the Hasimoto one-solitonic
filament.


title: Selfdecomposability and selfsimilarity: a concise primer

abstract:
  We summarize the relations among three classes of laws: infinitely divisible,
selfdecomposable and stable. First we look at them as the solutions of the
Central Limit Problem; then their role is scrutinized in relation to the Levy
and the additive processes with an emphasis on stationarity and selfsimilarity.
Finally we analyze the Ornstein-Uhlenbeck processes driven by Levy noises and
their selfdecomposable stationary distributions, and we end with a few
particular examples.


title: The Rest-Frame UV Spectrum of Elliptical Galaxies at High Redshift

abstract:
  Beyond redshift ~1.4 the only spectral feature that allows one to get the
redshift of passively evolving galaxies (PEG) with optical spectrographs is a
characteristic structure due to a set of iron and magnesium lines lines at
2600-2850 Angstrom in the rest frame. The same feature permits also to estimate
the time elapsed since the cessation of star formation. Current efforts at
observing high redshift PEGs at the VLT and SUBARU telescopes are briefly
reviewed.


title: Absence of magnetic ordering in NiGa_2S_4

abstract:
  Triangular-layered NiGa2S4, contrary to intuitive expectation, does not form
a noncollinear antiferromagnetic structure, as do isoelectronic NaCrO2 and
LiCrO2. Instead, the local magnetic moments remain disordered down to the
lowest measured temperature. To get more insight into this phenomenon, we have
performed first principles calculations of the first, second end third
neighbors exchange interactions, and found that the second neighbor exchange is
negligible, while the first and the third neighbor exchanges are comparable and
antiferromagnetic. Both are rapidly suppressed by the on-site Hubbard
repulsion.


title:
Cost-minimising strategies for data labelling : optimal stopping and
  active learning

abstract:
  Supervised learning deals with the inference of a distribution over an output
or label space $\CY$ conditioned on points in an observation space $\CX$, given
a training dataset $D$ of pairs in $\CX \times \CY$. However, in a lot of
applications of interest, acquisition of large amounts of observations is easy,
while the process of generating labels is time-consuming or costly. One way to
deal with this problem is {\em active} learning, where points to be labelled
are selected with the aim of creating a model with better performance than that
of an model trained on an equal number of randomly sampled points. In this
paper, we instead propose to deal with the labelling cost directly: The
learning goal is defined as the minimisation of a cost which is a function of
the expected model performance and the total cost of the labels used. This
allows the development of general strategies and specific algorithms for (a)
optimal stopping, where the expected cost dictates whether label acquisition
should continue (b) empirical evaluation, where the cost is used as a
performance metric for a given combination of inference, stopping and sampling
methods. Though the main focus of the paper is optimal stopping, we also aim to
provide the background for further developments and discussion in the related
field of active learning.


title: New HST Views at Old Stellar Systems

abstract:
  HST has recently revealed that many among the most massive globular clusters
harbor multiple stellar populations, and --most surprisingly-- some of them are
extremely helium rich. How these clusters managed to generate such complex
stellar populations, and what processes let to so dramatic helium enrichment,
is today one of the most exciting puzzles in the astrophysics of stellar
systems. HST has also been instrumental in demonstrating that both the bulge of
our own Galaxy and that of M31 are dominated by old stellar populations, coeval
to galactic globular clusters. Ultradeep HST imaging has also demonstrated that
a major component of the M31 halo is metal rich and much younger than old
globular clusters.


title: Several Dirac Operator in parabolic geometry

abstract:
  In this thesis, we show the existence of a sequence of differential operators
starting with with the Dirac operator in k Clifford variables, $D=(D_1,...,
D_k)$, where $D_i=\sum_j e_j\cdot \partial_{ij}: C^\infty((\R^n)^k,\S)\to
C^\infty((\R^n)^k,\S)$ ($\S$ is the spinor module). This operator is the
Cauchy-Riemann operator for n=2 and its resolution is the Dolbeault complex.
For higher n, the resolution of D is not known in general. While this problem
was treated many times in the language of Clifford analysis and some partial
results are known, we give a description of this operator in Parabolic
geometry, which is a special type of Cartan geometry modeled on $G/P$, where P
is a Parabolic subgroup of G. We construct sequences of invariant differential
operators starting with the Dirac operator in several variables and assume that
these sequences coinside in some cases with the resolution. We describe the
structure of these sequences precisely in case the dimension $n$ is odd and
give a conjecture that these sequences have similar structure for n even,
$k\leq n/2$ (the s.c. {\it stable range}). We also give some information about
these sequences in case n even, k>n/2. In the last chapter, explicite formulas
for the operators are derived for the case k=2.


title: Pade approximants of random Stieltjes series

abstract:
  We consider the random continued fraction S(t) := 1/(s_1 + t/(s_2 + t/(s_3 +
>...))) where the s_n are independent random variables with the same gamma
distribution. For every realisation of the sequence, S(t) defines a Stieltjes
function. We study the convergence of the finite truncations of the continued
fraction or, equivalently, of the diagonal Pade approximants of the function
S(t). By using the Dyson--Schmidt method for an equivalent one-dimensional
disordered system, and the results of Marklof et al. (2005), we obtain explicit
formulae (in terms of modified Bessel functions) for the almost-sure rate of
convergence of these approximants, and for the almost-sure distribution of
their poles.


title: Affineness of Deligne-Lusztig varieties for minimal length elements

abstract:
  We prove that the Deligne-Lusztig varieties associated to elements of the
Weyl group which are of minimal length in their twisted class are affine. Our
proof differs from the proof of He and Orlik-Rapoport and it is inspired by the
case of regular elements, which correspond to the varieties involved in
Brou\'e's conjectures.


title:
Band edge discontinuities and carrier transport in c-Si/porous silicon
  heterojunctions

abstract:
  We have prepared light emitting nanocrystalline porous silicon (PS) layers by
electrochemical anodization of crystalline silicon (c-Si) wafer and
characterized the c-Si/PS heterojunctions using temperature dependence of dark
current-voltage (I-V) characteristics. The reverse bias I-V characteristics of
c-Si/PS heterojunctions are found to behave like Schottky junctions where
carrier transport is mainly governed by the carrier generation-recombination in
the depletion region formed on the PS side. Fermi level of c-Si gets pinned to
the defect levels at the interface resulting in ln(I) proportional to V^0.5.
The barrier height in the reverse bias condition is shown to be equal to the
band offset at the conduction band edges. An energy band diagram for the
c-Si/PS heterojunction is proposed.


title: Twistor Strings with Flavour

abstract:
  We explore the tree-level description of a class of N=2 UV-finite SYM
theories with fundamental flavour within a topological B-model twistor string
framework. In particular, we identify the twistor dual of the Sp(N) gauge
theory with one antisymmetric and four fundamental hypermultiplets, as well as
that of the SU(N) theory with 2N hypermultiplets. This is achieved by suitably
orientifolding/orbifolding the original N=4 setup of Witten and adding a
certain number of new topological 'flavour'-branes at the orientifold/orbifold
fixed planes to provide the fundamental matter. We further comment on the
appearance of these objects in the B-model on CP(3|4). An interesting aspect of
our construction is that, unlike the IIB description of these theories in terms
of D3 and D7-branes, on the twistor side part of the global flavour symmetry is
realised geometrically. We provide evidence for this correspondence by
calculating and matching amplitudes on both sides.


title: Unstable GRB photospheres and electron-positron annihilation lines

abstract:
  We propose an emission mechanism of prompt gamma-ray bursts (GRBs) that can
reproduce the observed non-thermal spectra with high radiative efficiencies,
>50%. Internal dissipation below a photosphere can create a radiation-dominated
thermal fireball. If electron-positron pairs outnumber protons, radiative
acceleration of pairs drives the two-stream instabilities between pairs and
protons, leading to the ``proton sedimentation'' in the accelerating pair
frame. Pairs are continuously shock heated by proton clumps, scattering the
thermal photons into the broken power-law shape, with the non-thermal energy
that is comparable to the proton kinetic energy, consistent with observations.
Pair photospheres become unstable around the radius of the progenitor star
where strong thermalization occurs, if parameters satisfy the observed spectral
(Yonetoku) relation. Pair annihilation lines are predicted above continua,
which could be verified by GLAST.


title: Unitary constraints on Deeply Virtual Compton Scattering

abstract:
  At moderately low momentum transfer (-t up to 1 GeV^2) the coupling to the
vector meson production channels gives the dominant contribution to real
Compton and deeply virtual Compton scattering (DVCS). Starting from a Regge
Pole approach that successfully describes vector meson production, the singular
part of the corresponding box diagrams (where the intermediate vector
meson-baryon pair propagates on-shell) is evaluated without any further
assumptions (unitarity). Such a treatment explains not only the unexpectedly
large DVCS unpolarized cross section that has been recently measured at
Jefferson Laboratory (JLab), but also all the beam spin and charge asymmetries
that has been measured at JLab and Hermes, without explicit need of Generalized
Parton Distributions (GPD). The issue of the relationship between the two
approaches is addressed.


title:
The resonant damping of fast magnetohydrodynamic oscillations in a
  system of two coronal slabs

abstract:
  Observations of transversal coronal loop oscillations very often show the
excitation and damping of oscillations in groups of coronal loops rather than
in individual and isolated structures. We present results on the oscillatory
properties (periods, damping rates, and spatial distribution of perturbations)
for resonantly damped oscillations in a system of two inhomogeneous coronal
slabs and compare them to the properties found in single slab loop models. A
system of two identical coronal loops is modeled, in Cartesian geometry, as
being composed by two density enhancements. The linear magnetohydrodynamic
(MHD) wave equations for oblique propagation of waves are solved and the
damping of the different solutions, due to the transversal inhomogeneity of the
density profile, is computed. The physics of the obtained results is analyzed
by an examination of the perturbed physical variables. We find that, due to the
interaction between the loops, the normal modes of oscillation present in a
single slab split into symmetric and antisymmetric oscillations when a system
of two identical slabs is considered. The frequencies of these solutions may
differ from the single slab results when the distance between the loops is of
the order of a few slab widths. Oblique propagation of waves weakens this
interaction, since solutions become more confined to the edges of the slabs.
The damping is strong for surface-like oscillations, while sausage body-like
solutions are unaffected. For some solutions, and small slab separations, the
damping in a system of two loops differs substantially from the damping of a
single loop.


title: Saturation of elliptic flow and shear viscosity

abstract:
  Effect of shear viscosity on elliptic flow is studied in causal dissipative
hydrodynamics in 2+1 dimensions. Elliptic flow is reduced in viscous dynamics.
Causal evolution of minimally viscous fluid ($\eta/s$=0.08), can explain the
PHENIX data on elliptic flow in 16-23% Au+Au collisions up to $p_T\approx$3.6
GeV. In contrast, ideal hydrodynamics, can explain the same data only up to
$p_T\approx$1.5 GeV. $p_T$ spectra of identified particles are also better
explained in minimally viscous fluid than in ideal dynamics. However,
saturation of elliptic flow at large $p_T$ is not reproduced.


title: How many types of soliton solutions do we know?

abstract:
  We consider several ways of how one could classify the various types of
soliton solutions related to nonlinear evolution equations which are solvable
by the inverse scattering method. In doing so we make use of the fundamental
analytic solutions, the dressing procedure, the reduction technique and other
tools characteristic for that method.


title: Smooth toric DM stacks

abstract:
  We give a new definition of smooth toric DM stacks in the same spirit of
toric varieties. We show that our definition is equivalent to the one of
Borisov, Chen and Smith in terms of stacky fans. In particular, we give a
geometric interpretation of the combinatorial data contained in a stacky fan.
We also give a bottom up classification in terms of simplicial toric varieties
and fiber products of root stacks.


title:
Relaxational Singularities of Human Motor System at Aging Due to
  Short-Range and Long-Range Time Correlations

abstract:
  In this paper we study the relaxation singularities of human motor system at
aging. Our purpose is to examine the structure of force output variability as a
function of human aging in the time and frequency domains. For analysis of
experimental data we have developed here the statistical theory of relaxation
of force output fluctuation with taking into account the effects of two
relaxation channels. The first of them contains the contribution of short-range
correlation whereas other relaxation component reflects the effect of
long-range correlation. The analysis of experimental data shows, that the
general behavior of relaxation processes at human aging is determined by a
complicated combination and nonlinear interactions two above stated relaxation
processes as a whole.


title: Eutacticity in sea urchin evolution

abstract:
  An eutactic star, in a n-dimensional space, is a set of N vectors which can
be viewed as the projection of N orthogonal vectors in a N-dimensional space.
By adequately associating a star of vectors to a particular sea urchin we
propose that a measure of the eutacticity of the star constitutes a measure of
the regularity of the sea urchin. Then we study changes of regularity
(eutacticity) in a macroevolutive and taxonomic level of sea urchins belonging
to the Echinoidea Class. An analysis considering changes through geological
time suggests a high degree of regularity in the shape of these organisms
through their evolution. Rare deviations from regularity measured in
Holasteroida order are discussed.


title:
The assessment of the near infrared identification of Carbon stars. I.
  The Local Group galaxies WLM, IC 10 and NGC 6822

abstract:
  {The selection of AGB C and M stars from NIR colours has been done in recent
years using adjustable criteria that are in needs of standardization if one
wants to compare, in a coherent manner, properties of various populations.} We
intend to assess the NIR colour technique to identify C and M stars. We compare
the NIR colours of several C stars previously identified from spectroscopy or
narrow band techniques in WLM, IC 10 and NGC 6822. We demonstrate that very few
M stars have $(J-K)_0 > 1.4$ but a non negligible number of C stars are bluer
than this limit. Thus, counts of M and C stars based on such limit do not
produce pure samples. C/M ratios determined from NIR colours must be regarded
as underestimates mainly because the M numbers include many warm C stars and
also K stars if no blue limit is considered.


title: CODEX/ESPRESSO: the era of precision spectroscopy

abstract:
  CODEX is a high resolution spectrograph for the European ELT. CODEX is
conceived to reach the highest precision and stability, allowing the execution
of programs spanning many years. Several innovative technical concepts need to
be introduced to reach those excellent characteristics. Thus, the CODEX
consortium has foreseen the realization of a CODEX precursor at the VLT: the
ESPRESSO spectrograph. INAF is strongly committed in the ESPRESSO concept study
both in terms of financial and human resources.


title: On the number of stable quiver representations over finite fields

abstract:
  We prove a new formula for the generating function of polynomials counting
absolutely stable representations of quivers over finite fields. The case of
irreducible representations is studied in more detail.


title:
$\eta$ and $\eta'$ mesons in the Dyson-Schwinger approach at finite
  temperature

abstract:
  We study the temperature dependence of the pseudoscalar meson properties in a
relativistic bound-state approach exhibiting the chiral behavior mandated by
QCD. Concretely, we adopt the Dyson-Schwinger approach with a rank-2 separable
model interaction. After extending the model to the strange sector and fixing
its parameters at zero temperature, T=0, we study the T-dependence of the
masses and decay constants of all ground-state mesons in the pseudoscalar
nonet. Of chief interest are $\eta$ and $\eta^\prime$. The influence of the QCD
axial anomaly on them is successfully obtained through the Witten-Veneziano
relation at T=0. The same approach is then extended to T>0, using lattice QCD
results for the topological susceptibility. The most conspicuous finding is an
increase of the $\eta^\prime$ mass around the chiral restoration temperature
$T_{\rm Ch}$, which would suggest a suppression of $\eta^\prime$ production in
relativistic heavy-ion collisions. The increase of the $\eta^\prime$ mass may
also indicate that the extension of the Witten-Veneziano relation to finite
temperatures becomes unreliable around and above $T_{\rm Ch}$. Possibilities of
an improved treatment are discussed.


title: Super-inflation in Loop Quantum Cosmology

abstract:
  We investigate the dynamics of super-inflation in two versions of Loop
Quantum Cosmology, one in which the Friedmann equation is modified by the
presence of inverse volume corrections, and one in which quadratic corrections
are important. Computing the tilt of the power spectrum of the perturbed scalar
field in terms of fast-roll parameters, we conclude that the first case leads
to a power spectrum that is scale invariant for steep power law negative
potentials and for the second case, scale invariance is obtained for positive
potentials that asymptote to a constant value for large values of the scalar
field. It is found that in both cases, the horizon problem is solved with only
a few e-folds of super-inflationary evolution.


title: N=2 Supersymmetric Theories, Dyonic Charges and Instantons

abstract:
  This paper contains the results of our investigations of BPS instantons and
of our work on N=2 supersymmetric gauge theories. The BPS instantons we study
appear in type II string theory compactifications on Calabi-Yau threefolds. In
the corresponding four-dimensional effective supergravity actions the BPS
instantons arise as finite action solutions to the Euclidean equations of
motion. For N=2 supersymmetric gauge theories we construct general Lagrangians
involving gauge groups with (non-abelian) electric and magnetic (dyonic)
charges. In this work a coupling to hypermultiplets is included.


title: Generic Continuous Spectrum for Ergodic Schr"odinger Operators

abstract:
  We consider discrete Schr"odinger operators on the line with potentials
generated by a minimal homeomorphism on a compact metric space and a continuous
sampling function. We introduce the concepts of topological and metric
repetition property. Assuming that the underlying dynamical system satisfies
one of these repetition properties, we show using Gordon's Lemma that for a
generic continuous sampling function, the associated Schr"odinger operators
have no eigenvalues in a topological or metric sense, respectively. We present
a number of applications, particularly to shifts and skew-shifts on the torus.


title: Testing modified gravity with motion of satellites around galaxies

abstract:
  A modified gravity (MOG) theory, that has been successfully fitted to galaxy
rotational velocity data, cluster data, the Bullet Cluster 1E0657-56 and
cosmological observations, is shown to be in good agreement with the motion of
satellite galaxies around host galaxies at distances 50-400 kpc.


title:
Evolution of a Powerful Radio Loud Quasar 3C186 and its Impact on the
  Cluster Environment at z=1

abstract:
  X-ray cluster emission has been observed mainly in clusters with "inactive"
cD galaxies (L_bol ~1E40-1E43erg/sec), which do not show signs of accretion
onto a SMBH. Our recent Chandra discovery of ~100kpc scale diffuse X-ray
emission revealed the presence of an X-ray cluster associated with the radio
loud quasar 3C186 at redshift z=1.1 and suggests interactions between the
quasar and the cluster. In contrast to the majority of X-ray clusters the 3C186
cluster contains a quasar in the center whose radiative power alone exceeds
that which would be needed to quench the cluster cooling. We present the
Chandra X-ray data and new deep radio and optical images of this cluster. The
3C186 quasar is a powerful Compact Steep Spectrum radio source expanding into
the cluster medium. The 2arcsec radio jet is unresolved in the Chandra
observation, but its direction is orthogonal to the elliptical surface
brightness of the cluster. The radio data show the possible presence of old
radio lobes on 10 arcsec scale in the direction of the radio jet. We discuss
the nature of this source in the context of intermittent radio activity and the
interaction of the young expanding radio source with the cluster medium.


title:
Electroluminescence from single nanowires by tunnel injection: an
  experimental study

abstract:
  We present a hybrid light-emitting diode structure composed of an n-type
gallium nitride nanowire on a p-type silicon substrate in which current is
injected along the length of the nanowire. The device emits ultraviolet light
under both bias polarities. Tunnel-injection of holes from the p-type substrate
(under forward bias) and from the metal (under reverse bias) through thin
native oxide barriers consistently explains the observed electroluminescence
behaviour. This work shows that the standard p-n junction model is generally
not applicable to this kind of device structure.


title: Borel subalgebras of root-reductive Lie algebras

abstract:
  This paper generalizes the classification in a paper of Dimitrov and Penkov
of Borel subalgebras of gl_infty. Root-reductive Lie algebras are direct limits
of finite-dimensional reductive Lie algebras along inclusions preserving the
root spaces with respect to nested Cartan subalgebras. A Borel subalgebra of a
root-reductive Lie algebra is by definition a maximal locally solvable
subalgebra. The main general result of this paper is that a Borel subalgebra of
an infinite-dimensional indecomposable root-reductive Lie algebra is the
simultaneous stabilizer of a certain type of generalized flag in each of the
standard representations. For the three infinite-dimensional simple
root-reductive Lie algebras more precise results are obtained. The map sending
a maximal closed (isotropic) generalized flag in the standard representation to
its stabilizer hits Borel subalgebras, yielding a bijection in the cases of
sl_infty and sp_infty; in the case of so_infty the fibers are of size one and
two. A description is given of a nice class of toral subalgebras contained in
any Borel subalgebra. Finally, certain Borel subalgebras of a general
root-reductive Lie algebra are seen to correspond bijectively with Borel
subalgebras of the commutator subalgebra, which are understood in terms of the
special cases.


title: Black Hole Attractors in Extended Supergravity

abstract:
  We review some aspects of the attractor mechanism for extremal black holes of
(not necessarily supersymmetric) theories coupling Einstein gravity to scalars
and Maxwell vector fields. Thence, we consider N=2 and N=8, d=4 supergravities,
reporting some recent advances on the moduli spaces associated to BPS and
non-BPS attractor solutions supported by charge orbits with non-compact
stabilizers.


title: Pre-quantization of the Moduli Space of Flat G-Bundles over a Surface

abstract:
  For a simply connected, compact, simple Lie group G, the moduli space of flat
G-bundles over a closed surface is known to be pre-quantizable at integer
levels. For non-simply connected G, however, integrality of the level is not
sufficient for pre-quantization, and this paper determines the obstruction --
namely a certain cohomology class in H^3(G^2;Z) -- that places further
restrictions on the underlying level. The levels that admit a pre-quantization
of the moduli space are determined explicitly for all non-simply connected,
compact, simple Lie groups G.


title:
Black Hole Entropy Function, Attractors and Precision Counting of
  Microstates

abstract:
  In these lecture notes we describe recent progress in our understanding of
attractor mechanism and entropy of extremal black holes based on the entropy
function formalism. We also describe precise computation of the microscopic
degeneracy of a class of quarter BPS dyons in N=4 supersymmetric string
theories, and compare the statistical entropy of these dyons, expanded in
inverse powers of electric and magnetic charges, with a similar expansion of
the corresponding black hole entropy. This comparison is extended to include
the contribution to the entropy from multi-centered black holes as well.


title:
Atomic Structures of the Molecular Components in DNA and RNA based on
  Bond Lengths as Sums of Atomic Radii

abstract:
  The interpretation by the author in recent years of bond lengths as sums of
the relevant atomic or ionic radii has been extended here to the bonds in the
skeletal structures of adenine, guanine, thymine, cytosine, uracil, ribose,
deoxyribose and phosphoric acid. On examining the bond length data in the
literature, it has been found that the averages of the bond lengths are close
to the sums of the corresponding atomic covalent radii of carbon, nitrogen,
oxygen, hydrogen and phosphorus. Thus, the conventional molecular structures
have been resolved here, for the first time, into probable atomic structures.


title: Spin-wave spectra of a kagome stripe

abstract:
  We study ground state degeneracy and spin-wave excitations in a 1D version of
a Kagome antiferromagnet -- a Heisenberg antiferromagnet on a Kagome stripe. We
show that for nearest-neighbor interaction, the classical ground state is
infinitely degenerate. For any spin configuration from the degenerate set, the
classical spin-wave spectrum contains, in addition to Goldstone modes, a branch
of zero energy excitations, and a zero mode in another branch. We demonstrate
that the interactions beyond nearest neighbors lift the degeneracy, eliminate a
zero mode, and give a finite dispersion to formerly zero-energy branch, leaving
only Goldstone modes as zero-energy excitations.


title: Generalisations of the Tits representation

abstract:
  We construct a group K_n with properties similar to infinite Coxeter groups.
In particular, it has a geometric representation featuring hyperplanes and
simplicial chambers. The generators of K_n are given by 2-element subsets of
{0, .., n}. We give some easy combinatorial results on the finite residues of
K_n.


title: Fingerprints of spatial charge transfer in Quantum Cascade Lasers

abstract:
  We show that mid infrared transmission spectroscopy of a quantum cascade
laser provides clear cut information on changes in charge location at different
bias. Theoretical simulations of the evolution of the gain/absorption spectrum
for the $\lambda \sim$ 7.4 $\mu$m InGaAs/AlInAs/InP quantum cascade laser have
been compared with the experimental findings. Transfer of electrons between the
ground states in the active region and the states in the injector goes in hand
with a decrease of discrete intersubband absorption peaks and an increase of
broad high-energy absorption towards the continuum delocalised states above the
barriers.


title:
Optical Spectroscopic Classification and Membership of Young M Dwarfs in
  Star-Forming Regions

abstract:
  The spectral type is a key parameter in calibrating the temperature which is
required to estimate the mass of young stars and brown dwarfs. We describe an
approach developed to classify low-mass stars and brown dwarfs in the Trapezium
Cluster using red optical spectra, which can be applied to other star-forming
regions. The classification uses two methods for greater accuracy: the use of
narrowband spectral indices which rely on the variation of the strength of
molecular lines with spectral type and a comparison with other previously
classified young, low-mass objects in the Chamaeleon I star-forming region. We
have investigated and compared many different molecular indices and have
identified a small number of indices which work well for classifying M-type
objects in nebular regions. The indices are calibrated for young, pre-main
sequence objects whose spectra are affected by their lower surface gravities
compared with those on the main sequence. Spectral types obtained are
essentially independent of both reddening and nebular emission lines.
Confirmation of candidate young stars and brown dwarfs as bona fide cluster
members may be accomplished with moderate resolution spectra in the optical
region by an analysis of the strength of the gravity-sensitive Na doublet. It
has been established that this feature is much weaker in these very young
objects than in field dwarfs. A sodium spectral index is used to estimate the
surface gravity and to demonstrate quantitatively the difference between young
(1-2Myr) objects, and dwarf and giant field stars.


title: Seismic Fault Preserving Diffusion

abstract:
  This paper focuses on the denoising and enhancing of 3-D reflection seismic
data. We propose a pre-processing step based on a non linear diffusion
filtering leading to a better detection of seismic faults. The non linear
diffusion approaches are based on the definition of a partial differential
equation that allows us to simplify the images without blurring relevant
details or discontinuities. Computing the structure tensor which provides
information on the local orientation of the geological layers, we propose to
drive the diffusion along these layers using a new approach called SFPD
(Seismic Fault Preserving Diffusion). In SFPD, the eigenvalues of the tensor
are fixed according to a confidence measure that takes into account the
regularity of the local seismic structure. Results on both synthesized and real
3-D blocks show the efficiency of the proposed approach.


title: Resummation of Hadroproduction Cross-sections at High Energy

abstract:
  We reconsider the high energy resummation of photoproduction,
electroproduction and hadroproduction cross-sections, in the light of recent
progress in the resummation of perturbative parton evolution to NLO in
logarithms of Q^2 and x. We show in particular that the when the coupling runs
the dramatic enhancements seen at fixed coupling, due to infrared singularities
in the partonic cross-sections, are substantially reduced, to the extent that
they are largely accounted for by the usual NLO and NNLO perturbative
corrections. This leads to a novel explanation of the large K-factors commonly
found in perturbative calculations of hadroproduction cross-sections. We give
numerical estimates of high energy resummation effects for inclusive
B-production, inclusive jets, Drell-Yan and vector boson production, along with
their rapidity distributions. We find that resummation modifies the
B-production cross-section at the LHC by at most 15%, but that the enhancement
of gluonic W-production may be as large as 50% at large rapidities.


title:
A two-colour heterojunction unipolar nanowire light-emitting diode by
  tunnel injection

abstract:
  We present a systematic study of the current-voltage characteristics and
electroluminescence of gallium nitride (GaN) nanowire on silicon (Si) substrate
heterostructures where both semiconductors are n-type. A novel feature of this
device is that by reversing the polarity of the applied voltage the
luminescence can be selectively obtained from either the nanowire or the
substrate. For one polarity of the applied voltage, ultraviolet (and visible)
light is generated in the GaN nanowire, while for the opposite polarity
infrared light is emitted from the Si substrate. We propose a model, which
explains the key features of the data, based on electron tunnelling from the
valence band of one semiconductor into the conduction band of the other
semiconductor. For example, for one polarity of the applied voltage, given a
sufficient potential energy difference between the two semiconductors,
electrons can tunnel from the valence band of GaN into the Si conduction band.
This process results in the creation of holes in GaN, which can recombine with
conduction band electrons generating GaN band-to-band luminescence. A similar
process applies under the opposite polarity for Si light emission. This device
structure affords an additional experimental handle to the study of
electroluminescence in single nanowires and, furthermore, could be used as a
novel approach to two-colour light-emitting devices.


title: The influence of clumping on predicted O star wind parameters

abstract:
  We study the influence of clumping on the predicted wind structure of O-type
stars. For this purpose we artificially include clumping into our stationary
wind models. When the clumps are assumed to be optically thin, the radiative
line force increases compared to corresponding unclumped models, with a similar
effect on either the mass-loss rate or the terminal velocity (depending on the
onset of clumping). Optically thick clumps, alternatively, might be able to
decrease the radiative force.


title:
An optical spectroscopic H-R diagram for low-mass stars and brown dwarfs
  in Orion

abstract:
  The masses and temperatures of young low mass stars and brown dwarfs in star-
forming regions are not yet well established because of uncertainties in the
age of individual objects and the spectral type vs. temperature scale
appropriate for objects with ages of only a few Myr. Using multi-object optical
spectroscopy, 45 low-mass stars and brown dwarfs in the Trapezium Cluster in
Orion have been classified and 44 of these confirmed as bona fide cluster
members. The spectral types obtained have been converted to effective
temperatures using a temperature scale intermediate between those of dwarfs and
giants, which is suitable for young pre-main sequence objects. The objects have
been placed on an H-R diagram overlaid with theoretical isochrones. The low
mass stars and the higher mass substellar objects are found to be clustered
around the 1 Myr isochrone, while many of the lower mass substellar objects are
located well above this isochrone. An average age of 1 Myr is found for the
majority of the objects. Assuming coevality of the sources and an average age
of 1 Myr, the masses of the objects have been estimated and range from 0.018 to
0.44Msun. The spectra also allow an investigation of the surface gravity of the
objects by measurement of the sodium doublet equivalent width. With one
possible exception, all objects have low gravities, in line with young ages,
and the Na indices for the Trapezium objects lie systematically below those of
young stars and brown dwarfs in Chamaeleon, suggesting that the 820 nm Na index
may provide a sensitive means of estimating ages in young clusters.


title: Anomaly mediated neutrino-photon interactions at finite baryon density

abstract:
  We propose new physical processes based on the axial vector anomaly and
described by the Wess-Zumino-Witten term that couples the photon, Z-boson, and
the omega-meson. The interaction takes the form of a pseudo-Chern-Simons term,
$\sim \epsilon_{\mu\nu\rho\sigma}\omega^\mu Z^\nu F^{\rho\sigma}$. This term
induces neutrino-photon interactions at finite baryon density via the coupling
of the Z-boson to neutrinos. These interactions may be detectable in various
laboratory and astrophysical arenas. The new interactions may account for the
MiniBooNE excess. They also produce a competitive contribution to neutron star
cooling at temperatures >10^9 K. These processes and related axion--photon
interactions at finite baryon density appear to be relevant in many
astrophysical regimes.


title: Solving the SUSY Flavour and CP Problems with SU(3) Family Symmetry

abstract:
  We show how the SUSY flavour and CP problems can be solved using gauged SU(3)
family symmetry previously introduced to describe quark and lepton masses and
mixings, in particular neutrino tri-bimaximal mixing via constrained sequential
dominance. The Yukawa and soft trilinear and scalar mass squared matrices and
kinetic terms are expanded in powers of the flavons used to spontaneously break
the SU(3) family symmetry, and the canonically normalized versions of these
matrices are constructed. The soft mass matrices are then expressed in the
Super-CKM basis, and the leading order mass insertion parameters are
calculated, and are shown to satisfy the experimental constraints from flavour
changing neutral current processes. Assuming that CP is spontaneously broken by
the flavons, the next-to-leading order effects responsible for CP violation are
then estimated, and the predictions for electric dipole moments are shown to be
an order of magnitude more suppressed than those predicted from the constrained
minimal supersymmetric standard model (CMSSM), and may be further suppressed if
the high energy trilinear soft parameter is assumed to be relatively small. We
also predict that, unlike in the CMSSM, epsilon_K'/epsilon_K may be dominated
by the SUSY operator O_8. We also discuss the additional constraints from
unification, which can lead to further predictions for flavour changing in our
scheme.


title: Pre-Holography

abstract:
  We construct a symplectic isomorphism, h, from classical Klein Gordon
solutions of mass m on (d+1)-dimensional Lorentzian Anti de Sitter space
(equipped with the usual symplectic form) to a certain symplectic space of
functions on its conformal boundary (only) for all integer and half-integer
Delta (= d/2 + (1/2)(d^2 + 4m^2)^{1/2}). h induces a large family of new
examples of Rehren's algebraic holography in which the net of local quantum
Klein Gordon algebras in AdS is seen to map to a suitably defined net of local
algebras for the (generalized free) scalar conformal field with anomalous
dimension Delta on d-dimensional Minkowski space (the AdS boundary). Relatedly,
we show for these models that Bertola et al's boundary-limit holography becomes
a quantum duality (only) if the test functions for boundary Wightman
distributions are restricted in a particular way.


title:
Implications of vacuum stability constraints on the nonminimal
  supersymmetric standard model with lepton number violation

abstract:
  We carry out a detailed analysis of the scalar sector of the nonminimal
supersymmetric standard model with lepton number violation, and study the
constraints imposed on it by the stability of the electroweak symmetry breaking
vacuum. The model contains a trilinear lepton mumber violating term in the
superpotential together with the associated \susy breaking interactions which
can give rise to neutrino masses. We evaluate the mass matrices for the various
boson and fermion modes and then discuss the effect that the lepton number
violating interactions have on the mass spectra using a phenomenological
precription to implement the experimental constraints on the light neutrinos
mass matrix. We also discuss qualitatively the conditions on the lepton number
violating parameters set by the unbounded from below directions, and from the
absence of the charge and color breaking minima in this model.


title: A Secret Symmetry of the AdS/CFT S-matrix

abstract:
  We find a new quantum Yangian symmetry of the AdS/CFT S-matrix, which
complements the original su(2|2) symmetry to gl(2|2) and does not have a Lie
algebra analog. Our finding is motivated by the Yangian double structure
discovered at the classical level.


title: Calibrated associative and Cayley embeddings

abstract:
  Using the Cartan-Kahler theory, and results on real algebraic structures, we
prove two embedding theorems. First, the interior of a smooth, compact
3-manifold may be isometrically embedded into a G_2-manifold as an associative
submanifold. Second, the interior of a smooth, compact 4-manifold K, whose
double has a trivial bundle of self-dual 2-forms, may be isometrically embedded
into a Spin(7)-manifold as a Cayley submanifold. Along the way, we also show
that Bochner's Theorem on real analytic approximation of smooth differential
forms, can be obtained using real algebraic tools developed by Akbulut and
King.


title: Universal derived equivalences of posets of tilting modules

abstract:
  We show that for two quivers without oriented cycles related by a BGP
reflection, the posets of their tilting modules are related by a simple
combinatorial construction, which we call flip-flop.
  We deduce that the posets of tilting modules of derived equivalent path
algebras of quivers without oriented cycles are universally derived equivalent.


title: Dynamical approach to chains of scatterers

abstract:
  Linear chains of quantum scatterers are studied in the process of
lengthening, which is treated and analysed as a discrete dynamical system
defined over the manifold of scattering matrices. Elementary properties of such
dynamics relate the transport through the chain to the spectral properties of
individual scatterers. For a single-scattering channel case some new light is
shed on known transport properties of disordered and noisy chains, whereas
translationally invariant case can be studied analytically in terms of a simple
deterministic dynamical map. The many-channel case was studied numerically by
examining the statistical properties of scatterers that correspond to a certain
type of transport of the chain i.e. ballistic or (partially) localised.


title: Winds from clu\sters with non-uniform stellar distributions

abstract:
  We present analytic and numerical models of the `cluster wind' resulting from
the multiple interactions of the winds ejected by the stars of a dense cluster
of massive stars. We consider the case in which the distribution of stars
(i.e., the number of stars per unit volume) within the cluster is spherically
symmetric, has a power-law radial dependence, and drops discontinuously to zero
at the outer radius of the cluster. We carry out comparisons between an
analytic model (in which the stars are considered in terms of a spatially
continuous injection of mass and energy) and 3D gasdynamic simulations (in
which we include 100 stars with identical winds, located in 3D space by
statistically sampling the stellar distribution function). From the analytic
model, we find that for stellar distributions with steep enough radial
dependencies the cluster wind flow develops a very high central density and a
non-zero central velocity, and for steeper dependencies it becomes fully
supersonic throughout the volume of the cluster (these properties are partially
reproduced by the 3D numerical simulations). Therefore, the wind solutions
obtained for stratified clusters can differ dramatically from the case of a
homogeneous stellar distribution (which produces a cluster wind with zero
central velocity, and a fully subsonic flow within the cluster radius).
Finally, from our numerical simulations we compute predictions of X-ray
emission maps and luminosities, which can be directly compared with
observations of cluster wind flows.


title: On Almost Representations of Property (T) Groups

abstract:
  Property (T) for groups means a dichotomy: a representation either has an
invariant vector or all vectors are far from being invariant. We show that,
under a stronger condition of A.Zuk, a similar dichotomy holds for almost
representations as well.


title:
Unusual heavy-mass nearly ferromagnetic state with a surprisingly large
  Wilson ratio in the double layered ruthenates
  (Sr$_{1-x}$Ca$_{x}$)$_{3}$Ru$_{2}$O$_{7}$

abstract:
  We report an unusual nearly ferromagnetic, heavy-mass state with a
surprisingly large Wilson ratio $R_{\textrm{w}}$ (e.g., $R_{\textrm{w}}\sim$
700 for $x =$ 0.2) in double layered ruthenates
(Sr$_{1-x}$Ca$_{x}$)$_{3}$Ru$_{2}$O$_{7}$ with 0.08 $< x <$ 0.4. This state
does not evolve into a long-range ferromagnetically ordered state despite
considerably strong ferromagnetic correlations, but freezes into a
cluster-spin-glass at low temperatures. In addition, evidence of non-Fermi
liquid behavior is observed as the spin freezing temperature of the
cluster-spin-glass approaches zero near $x \approx$ 0.1. We discuss the origin
of this unique magnetic state from the Fermi surface information probed by Hall
effect measurements.


title:
Periodic orbit bifurcations as an ionization mechanism: The
  bichromatically driven hydrogen atom

abstract:
  We investigate the multiphoton ionization of hydrogen driven by a strong
bichromatic microwave field. In a regime where classical and quantum
simulations agree, periodic orbit analysis captures the mechanism: Through the
linear stability of periodic orbits we match qualitatively the variation of
experimental ionization rates with control parameters such as the amplitudes of
the two modes of the field or their relative phases. Moreover, we discuss an
empirical formula which reproduces quantum simulations to a high degree of
accuracy. This quantitative agreement shows the mechanism by which short
periodic orbits organize the dynamics in multiphoton ionization. We also
analyze the effect of longer pulse durations. Finally we compare our results
with those based on the peak amplitude rule. Both qualitative and quantitative
analyses are implemented for different mode locked fields. In parameter space,
the localization of the period doubling and halving allows one to predict the
set of parameters (amplitudes and phase lag) where ionization occurs.


title: Lattice QCD at finite temperature and density

abstract:
  QCD at finite temperature and density is becoming increasingly important for
various experimental programmes, ranging from heavy ion physics to
astro-particle physics. The non-perturbative nature of non-abelian quantum
field theories at finite temperature leaves lattice QCD as the only tool by
which we may hope to come to reliable predictions from first principles. This
requires careful extrapolations to the thermodynamic, chiral and continuum
limits in order to eliminate systematic effects introduced by the
discretization procedure. After an introduction to lattice QCD at finite
temperature and density, its possibilities and current systematic limitations,
a review of present numerical results is given. In particular, plasma
properties such as the equation of state, screening masses, static quark free
energies and spectral functions are discussed, as well as the critical
temperature and the QCD phase structure at zero and finite density.


title: Nanoindentation-Induced Phase Transformation in Silicon

abstract:
  Nanoindentation-induced phase transformation in silicon has been studied. A
series of nanoindentations were made with the sharp diamond Berkovich tip.
During nanoindentations, maximum load ranged from 2000 $\mu$N to 5000 $\mu$N,
with a 1000 $\mu$N/sec loading rate. Slow unloading rate at 100$\mu$N/sec was
chosen to favor the formation of the crystalline end phases, high pressure
phase (Si-III and Si-XII). Fast unloading rate at 1000$\mu$N/sec was used to
obtain amorphous phase. The phase transformation was examined by Raman
spectroscopy and plan-view transmission electron microscopy (TEM). HPP have
been identified even if no "pop-in" and "pop-out" observed in load-depth
characteristics curves. HPP appeared in c-Si when the maximum load up to 3000
$\mu$N. TEM images have been revealed that the optimization HPP transformation
in c-Si at the nanoscale occurred when the maximum load applied at 5000 $\mu$N.


title: Why rooting fails

abstract:
  I explore the origins of the unphysical predictions from rooted staggered
fermion algorithms. Before rooting, the exact chiral symmetry of staggered
fermions is a flavored symmetry among the four "tastes." The rooting procedure
averages over tastes of different chiralities. This averaging forbids the
appearance of the correct 't Hooft vertex for the target theory.


title: Doped Nano-Electromechanical Systems

abstract:
  We present a new generation of nano-electromechanical systems (NEMS), which
are realized by doping the semiconductor base material. In contrast to the
traditional approach these doped NEMS (D-NEMS) do not require a metallization
layer. This makes them far lighter and hence increases resonance frequency and
quality factor. Additionally, D-NEMS can be tuned from the conductive state
into an insulating one. This will enable a host of new device designs, like
mechanically tunable pin-junctions and nanomechanical single electron switches.
We demonstrate D-NEMS fabrication and operation from the intrinsic, to the
light, and to the heavy regime of doping.


title: Decoherent quantum walks driven by a generic coin operation

abstract:
  We consider the effect of different unitary noise mechanisms on the evolution
of a quantum walk (QW) on a linear chain with a generic coin operation: (i)
bit-flip channel noise, restricted to the coin subspace of the QW, and (ii)
topological noise caused by randomly broken links in the linear chain.
Similarities and differences in the respective decoherent dynamics of the
walker as a function of the probability per unit time of a decoherent event
taking place are discussed.


title: Carbon nanotube array vias for interconnect applications

abstract:
  The material and electrical properties of the CNT single vias and array vias
grown by microwave plasma-enhanced chemical vapor deposition were investigated.
The diameters of multiwall carbon nanotubes (MWNTs) grown on the bottom
electrode of Ta decrease with increasing pretreatment power and substrate
temperature while the effects of the growth power and methane flow ratio are
insignificant The decrease of CNT diameters leads to the decrease of the CNT
via diode devices. The increase of growth power enhances the CNT graphitization
degree and thue the conductivity of CNT via diode devices. In the same via
region, the MWNT diode resistances of the array vias are lower than those of
the single vias. The MWNT diode resistances on the bottom electrode of titanium
are lower than those on the bottom electrode of tantalum. It may be attributed
to the smaller tube diameters on the bottom electrode of Ti and the work
function difference between Ta and Ti films with respect to the work function
of CNTs.


title: Correction to: HZ-algebra spectra are differential graded algebras

abstract:
  This correction article is actually unnecessary.
  The proof of Theorem 1.2, concerning commutative HQ-algebra spectra and
commutative differential graded algebras, in the author's paper [American
Journal of Mathematics vol. 129 (2007) 351-379 (arxiv:math/0209215v4)] is
correct as originally stated. Neil Strickland carefully proved that D is
symmetric monoidal; so Proposition 4.7 and hence also Theorem 1.2 hold as
stated. Strickland's proof will appear in joint work with Stefan Schwede; see
related work in Strickland's [arxiv:0810.1747]. Note here D is defined as a
colimit of chain complexes; in contrast, non-symmetric monoidal functors
analogous to D are defined as homotopy colimits of spaces in previous work of
the author.


title:
Polariton amplification in a multiple-quantum-well resonant photonic
  crystal

abstract:
  Based on a microscopic many-particle theory we study the amplification of
polaritons in a multiple-quantum-well resonant photonic crystal. For the
Bragg-spaced multiple quantum wells under investigation we predict that in a
typical pump-probe setup four-wave mixing processes can lead to an unstable
energy transfer from the pump into the probe and the background-free four-wave
mixing directions. We find that under certain excitation conditions this
phase-conjugate oscillation induced instability can lead to a large
amplification of the weak probe pulse.


title:
CP violation in Charged Higgs Bosons decays $H^\pm \to W^\pm (\gamma,
  Z)$ in the Minimal Supersymmetric Standard Model (MSSM)

abstract:
  One loop mediated charged Higgs bosons decays $H^\pm\to W^\pm V$, $V= Z,
\gamma$ are studied in the Minimal Supersymmetric Standard Model (MSSM) with
and without CP violating phases. We evaluate the MSSM contributions to these
processes taking into account $B\to X_s\gamma$ constraint as well as
experimental constraints on the MSSM parameters. In the MSSM, we found that in
the intermediate range of $\tan\beta \la 10$ and for large
  A_t and large $\mu$, where the lightest top squark becomes very light and
hence non-decoupled, the branching ratio of $H^\pm \to W^{\pm} Z$ can be of the
order 10^{-3} while the branching ratio of $H^\pm \to W^{\pm} \gamma$ is of the
order 10^{-5}. We found also that the CP violating phases of soft SUSY
parameters can modify the branching ratio by about one order of magnitude. We
also show that MSSM with CP violating phases lead to CP-violating asymmetry in
the decays $H^+ \to W^+V$ and $H^- \to W^-V$. Such CP asymmetry can be rather
large and can reach 80% in some region of parameter space.


title:
Coexistence of tetrahedral and octahedral-like sites in amorphous phase
  change materials

abstract:
  Chalcogenide alloys are materials of interest for optical recording and
non-volatile memories. We perform ab-initio molecular dynamics simulations
aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the
prototypical material in this class. First principles simulations show that
amorphous GST obtained by quenching from the liquid phase displays two types of
short range order. One third of Ge atoms are in a tetrahedral environment while
the remaining Ge, Sb and Te atoms display a defective octahedral environment,
reminiscent of cubic crystalline GST.


title: Search for the decay B+ -> K+ tau-/+ mu+/-

abstract:
  We present a search for the lepton flavor violating decay B+ --> K+ tau-/+
mu+/- using 383 million B Bbar events collected by the BABAR experiment. The
branching fraction for this decay can be substantially enhanced in new physics
models. The kinematics of the tau from the signal B decay are inferred from the
K+, mu, and other B in the event, which is fully reconstructed in one of a
variety of hadronic decay modes, allowing the signal B candidate to be fully
reconstructed. We observe no excess of events over the expected background and
set a limit of B(B+ --> K+ tau mu) < 7.7 x 10^-5 at 90% confidence level, where
the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+ mu- final
states. We use this result to improve a model-independent bound on the energy
scale of flavor-changing new physics.


title: Interaction-Induced Strong Localization in Quantum Dots

abstract:
  We argue that Coulomb blockade phenomena are a useful probe of the cross-over
to strong correlation in quantum dots. Through calculations at low density
using variational and diffusion quantum Monte Carlo (up to r_s ~ 55), we find
that the addition energy shows a clear progression from features associated
with shell structure to those caused by commensurability of a Wigner crystal.
This cross-over (which occurs near r_s ~ 20 for spin-polarized electrons) is,
then, a signature of interaction-driven localization. As the addition energy is
directly measurable in Coulomb blockade conductance experiments, this provides
a direct probe of localization in the low density electron gas.


title: An XMM-Newton survey of broad iron lines in Seyfert galaxies

abstract:
  We present an analysis of the X-ray spectra of a sample of 37 observations of
26 Seyfert galaxies observed by XMM-Newton in order to characterize their iron
K emission. All objects show evidence for iron line emission in the 6-7 keV
band. A narrow core at 6.4 keV is seen almost universally in the spectra, and
we model this using a neutral Compton reflection component, assumed to be
associated with distant, optically thick material such as the molecular torus.
Once this, and absorption by a zone of ionized gas in the line-of-sight is
accounted for, less than half of the sample observations show an acceptable
fit. Approximately 2/3 of the sample shows evidence for further, broadened
emission in the iron K-band. When modeled with a Gaussian, the inferred energy
is close to that expected for neutral iron, with a slight redshift, with an
average velocity width of ~0.1c. The mean parameters are consistent with
previous ASCA results and support the idea that the broad components can be
associated with the accretion disk. Before proceeding to that conclusion, we
test an alternative model comprising a blend of 3-4 narrow, unshifted emission
lines (including the 6.4 keV core), together with 1-2 zones of highly ionized
gas in the line-of-sight. Around 1/3 of the objects are not adequately fit by
this model, and in general better fits are obtained with a relativistic disk
line model, which has fewer free parameters. Nonetheless we find that
absorption by ionized gas affects the spectrum above 2.5 keV in approximately
half the sample. There is evidence for multiple ionized zones in at least 3
objects, but in all those cases a blurred reflector is required in addition to
the complex absorption. (truncated)